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                                  THE

                                HISTORY

                                  OF

                              CHEMISTRY.


                                  BY

                         THOMAS THOMSON, M. D.
                  F.R.S. L. & E.; F.L.S.; F.G.S., &c.

      REGIUS PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF GLASGOW.


                            IN TWO VOLUMES.

                               VOL. II.

                                LONDON:
                  HENRY COLBURN AND RICHARD BENTLEY,
                        NEW BURLINGTON STREET.

                                 1831.


                  C. WHITING, BEAUFORT HOUSE, STRAND.




                               CONTENTS

                                  OF

                          THE SECOND VOLUME.


  CHAPTER I.                                                     Page

  Of the foundation and progress of scientific chemistry in Great
  Britain                                                           1


  CHAPTER II.

  Of the progress of philosophical chemistry in Sweden             26


  CHAPTER III.

  Progress of scientific chemistry in France                       75


  CHAPTER IV.

  Progress of analytical chemistry                                190


  CHAPTER V.

  Of electro-chemistry                                            251


  CHAPTER VI.

  Of the atomic theory                                            277


  CHAPTER VII.

  Of the present state of chemistry                               309




                         HISTORY OF CHEMISTRY.




CHAPTER I.

OF THE FOUNDATION AND PROGRESS OF SCIENTIFIC CHEMISTRY IN GREAT BRITAIN.


While Mr. Cavendish was extending the bounds of pneumatic chemistry,
with the caution and precision of a Newton, Dr. Priestley, who had
entered on the same career, was proceeding with a degree of rapidity
quite unexampled; while from his happy talents and inventive faculties,
he contributed no less essentially to the progress of the science, and
certainly more than any other British chemist to its popularity.

Joseph Priestley was born in 1733, at Fieldhead, about six miles from
Leeds in Yorkshire. His father, Jonas Priestley, was a maker and
dresser of woollen cloth, and his mother, the only child of Joseph
Swift a farmer in the neighbourhood. Dr. Priestley was the eldest
child; and, his mother having children very fast, he was soon committed
to the care of his maternal grandfather. He lost his mother when he
was only six years of age, and was soon after taken home by his father
and sent to school in the neighbourhood. His father being but poor,
and encumbered with a large family, his sister, Mrs. Keighley, a woman
in good circumstances, and without children, relieved him of all care
of his eldest son, by taking him and bringing him up as her own. She
was a dissenter, and her house was the resort of all the dissenting
clergy in the country. Young Joseph was sent to a public school in
the neighbourhood, and, at sixteen, had made considerable progress in
Latin, Greek, and Hebrew. Having shown a passion for books and for
learning at a very early age, his aunt conceived hopes that he would
one day become a dissenting clergyman, which she considered as the
first of all professions; and he entered eagerly into her views: but
his health declining about this period, and something like phthisical
symptoms having come on, he was advised to turn his thoughts to trade,
and to settle as a merchant in Lisbon. This induced him to apply to the
modern languages; and he learned French, Italian, and German, without a
master. Recovering his health, he abandoned his new scheme and resumed
his former plan of becoming a clergyman. In 1752 he was sent to the
academy of Daventry, to study under Dr. Ashworth, the successor of Dr.
Doddridge. He had already made some progress in mechanical philosophy
and metaphysics, and dipped into Chaldee, Syriac, and Arabic. At
Daventry he spent three years, engaged keenly in studies connected with
divinity, and wrote some of his earliest theological tracts. Freedom
of discussion was admitted to its full extent in this academy. The two
masters espoused different sides upon most controversial subjects, and
the scholars were divided into two parties, nearly equally balanced.
The discussions, however, were conducted with perfect good humour
on both sides; and Dr. Priestley, as he tells us himself, usually
supported the heterodox opinion; but he never at any time, as he
assures us, advanced arguments which he did not believe to be good,
or supported an opinion which he did not consider as true. When he
left the academy, he settled at Needham in Suffolk, as an assistant
in a small, obscure dissenting meeting-house, where his income never
exceeded 30_l._ a-year. His hearers fell off, in consequence of their
dislike of his theological opinions; and his income underwent a
corresponding diminution. He attempted a school; but his scheme failed
of success, owing to the bad opinion which his neighbours entertained
of his orthodoxy. His situation would have been desperate, had he not
been occasionally relieved by sums out of charitable funds, procured by
means of Dr. Benson, and Dr. Kippis.

Several vacancies occurred in his vicinity; but he was treated with
contempt, and thought unworthy to fill any of them. Even the dissenting
clergy in the neighbourhood thought it a degradation to associate
with him, and durst not ask him to preach: not from any dislike to
his theological opinions; for several of them thought as freely as
he did; but because the genteeler part of their audience always
absented themselves when he appeared in the pulpit. A good many years
afterwards, as he informs us himself, when his reputation was very
high, he preached in the same place, and multitudes flocked to hear the
very same sermons, which they had formerly listened to with contempt
and dislike.

His friends being aware of the disagreeable nature of his situation
at Needham, were upon the alert to procure him a better. In 1758, in
consequence of the interest of Mr. Gill, he was invited to appear as a
candidate for a meeting-house in Sheffield, vacant by the resignation
of Mr. Wadsworth. He appeared accordingly and preached, but was not
approved of. Mr. Haynes, the other minister, offered to procure him a
meeting-house at Nantwich in Cheshire. This situation he accepted, and,
to save expenses, he went from Needham to London by sea. At Nantwich
he continued three years, and spent his time much more agreeably
than he had done at Needham. His opinions were not obnoxious to his
hearers, and controversial discussions were never introduced. Here he
established a school, and found the business of teaching, contrary
to his expectation, an agreeable and even interesting employment. He
taught from seven in the morning, till four in the afternoon; and after
the school was dismissed, he went to the house of Mr. Tomlinson, an
eminent attorney in the neighbourhood, where he taught privately till
seven in the evening. Being thus engaged twelve hours every day in
teaching, he had little time for private study. It is, indeed, scarcely
conceivable how, under such circumstances, he could prepare himself for
Sunday. Here, however, his circumstances began to mend. At Needham it
required the utmost economy to keep out of debt; but at Nantwich, he
was able to purchase a few books and some philosophical instruments, as
a small air-pump, an electrical machine, &c. These he taught his eldest
scholars to keep in order and manage: and by entertaining their parents
and friends with experiments, in which the scholars were generally the
operators, and sometimes the lecturers too, he considerably extended
the reputation of his school. It was at Nantwich that he wrote his
grammar for the use of his school, a book of considerable merit, though
its circulation was never extensive. This latter circumstance was
probably owing to the superior reputation of Dr. Lowth, who published
his well-known grammar about two years afterwards.

Being boarded in the house of Mr. Eddowes, a very sociable and sensible
man, and a lover of music, Dr. Priestley was induced to play a little
on the English flute; and though he never was a proficient, he informs
us that it contributed more or less to his amusement for many years. He
recommends the knowledge and practice of music to all studious persons,
and thinks it rather an advantage for them if they have no fine ear or
exquisite taste, as they will, in consequence, be more easily pleased,
and less apt to be offended when the performances they hear are but
indifferent.

The academy at Warrington was instituted while Dr. Priestley was at
Needham, and he was recommended by Mr. Clark, Dr. Benson, and Dr.
Taylor, as tutor in the languages; but Dr. Aiken, whose qualifications
were considered as superior, was preferred before him. However, on
the death of Dr. Taylor, and the advancement of Dr. Aiken to be tutor
in divinity, he was invited to succeed him: this offer he accepted,
though his school at Nantwich was likely to be more gainful; for the
employment at Warrington was more liberal and less painful. In this
situation he continued six years, actively employed in teaching and
in literary pursuits. Here he wrote a variety of works, particularly
his History of Electricity, which first brought him into notice as
an experimental philosopher, and procured him celebrity. After the
publication of this work, Dr. Percival of Manchester, then a student
at Edinburgh, procured him the title of doctor in laws, from that
university. Here he married a daughter of Mr. Isaac Wilkinson, an
ironmonger in Wales; a woman whose qualities he has highly extolled,
and who died after he went to America.

In the academy he spent his time very happily, but it did not flourish.
A quarrel had broken out between Dr. Taylor and the trustees, in
consequence of which all the friends of that gentleman were hostile
to the institution. This, together with the smallness of his income,
100_l._ a-year, and 15_l._ for each boarder, which precluded him
from making any provision for his family, induced him to accept an
invitation to take charge of Millhill chapel, at Leeds, where he had a
considerable acquaintance, and to which he removed in 1767.

Here he engaged keenly in the study of theology, and produced a great
number of works, many of them controversial. Here, too, he commenced
his great chemical career, and published his first tract on _air_.
He was led accidentally to think of pneumatic chemistry, by living
in the immediate vicinity of a brewery. Here, too, he published his
history of the Discoveries relative to Light and Colours, as the first
part of a general history of experimental philosophy; but the expense
of this book was so great, and its sale so limited, that he did not
venture to prosecute the undertaking. Here, likewise, he commenced and
published three volumes of a periodical work, entitled "The Theological
Repository," which he continued after he settled in Birmingham.

After he had been six years at Leeds, the Earl of Shelburne (afterwards
Marquis of Lansdowne), engaged him, on the recommendation of Dr.
Price, to live with him as a kind of librarian and literary companion,
at a salary of 250_l._ a-year, with a house. With his lordship he
travelled through Holland, France, and a part of Germany, and spent
some time in Paris. He was delighted with this excursion, and expressed
himself thoroughly convinced of the great advantages to be derived
from foreign travel. The men of science and politicians in Paris were
unbelievers, and even professed atheists, and as Dr. Priestley chose
to appear before them as a Christian, they told him that he was the
first person they had met with, of whose understanding they had any
opinion, who was a believer of Christianity; but, upon interrogating
them closely, he found that none of them had any knowledge either of
the nature or principles of the Christian religion.--While with Lord
Shelburne, he published the first three volumes of his Experiments on
Air, and had collected materials for a fourth, which he published soon
after settling in Birmingham. At this time also he published his attack
upon Drs. Reid, Beattie, and Oswald; a book which, he tells us, he
finished in a fortnight: but of which he afterwards, in some measure,
disapproved. Indeed, it was impossible for any person of candour to
approve of the style of that work, and the way in which he treated Dr.
Reid, a philosopher certainly much more deeply skilled than himself in
metaphysics.

After some years Lord Shelburne began to be weary of his associate,
and, on his expressing a wish to settle him in Ireland, Dr. Priestley
of his own accord proposed a separation, to which his lordship
consented, after settling on him an annuity of 150_l._, according to a
previous stipulation. This annuity he continued regularly to pay during
the remainder of the life of Dr. Priestley.

His income being much diminished by his separation from Lord Shelburne,
and his family increasing, he found it now difficult to support
himself. At this time Mrs. Rayner made him very considerable presents,
particularly at one period a sum of 400_l._; and she continued her
contributions to him almost annually. Dr. Fothergill had proposed a
subscription, in order that he might prosecute his experiments to their
utmost extent, and be enabled to live without sacrificing his time to
his pupils. This he accepted. It amounted at first to 40_l._ per annum,
and was afterwards much increased. Dr. Watson, Mr. Wedgewood, Mr.
Galton, and four or five more, were the gentlemen who joined with Dr.
Fothergill in this generous subscription.

Soon after, he settled in a meeting-house in Birmingham, and continued
for several years engaged in theological and chemical investigations.
His apparatus, by the liberality of his friends, had become excellent,
and his income was so good that he could prosecute his researches to
their full extent. Here he published the three last volumes of his
Experiments on Air, and various papers on the same subject in the
Philosophical Transactions. Here, too, he continued his Theological
Repository, and published a variety of tracts on his peculiar opinions
in religion, and upon the history of the primitive church. He now
unluckily engaged in controversy with the established clergy of the
place; and expressed his opinions on political subjects with a degree
of freedom, which, though it would have been of no consequence at
any former period, was ill suited to the peculiar circumstances that
were introduced into this country by the French revolution, and to
the political maxims of Mr. Pitt and his administration. His answer
to Mr. Burke's book on the French revolution excited the violent
indignation of that extraordinary man, who inveighed against his
character repeatedly, and with peculiar virulence, in the house of
commons. The clergy of the church of England, too, who began about this
time to be alarmed for their establishment, of which Dr. Priestley
was the open enemy, were particularly active; the press teemed with
their productions against him, and the minds of their hearers seem to
have been artificially excited; indeed some of the anecdotes told of
the conduct of the clergy of Birmingham, were highly unbecoming their
character. Unfortunately, Dr. Priestley did not seem to be aware of
the state of the nation, and of the plan of conduct laid down by Mr.
Pitt and his political friends; and he was too fond of controversial
discussions to yield tamely to the attacks of his antagonists.

These circumstances seem in some measure to explain the disgraceful
riots which took place in Birmingham in 1791, on the day of the
anniversary of the French revolution. Dr. Priestley's meeting-house and
his dwelling-house were burnt; his library and apparatus destroyed,
and many manuscripts, the fruits of several years of industry, were
consumed in the conflagration. The houses of several of his friends
shared the same fate, and his son narrowly escaped death, by the care
of a friend who forcibly concealed him for several days. Dr. Priestley
was obliged to make his escape to London, and a seat was taken for him
in the mail-coach under a borrowed name. Such was the ferment against
him that it was believed he would not have been safe any where else;
and his friends would not allow him, for several weeks, to walk through
the streets.

He was invited to Hackney, to succeed Dr. Price in the meeting-house
of that place. He accepted the office, but such was the dread of his
unpopularity, that nobody would let him a house, from an apprehension
that it would be burnt by the populace as soon as it was known that he
inhabited it. He was obliged to get a friend to take a lease of a house
in another name; and it was with the utmost difficulty that he could
prevail with the landlord to allow the lease to be transferred to him.
The members of the Royal Society, of which he was a fellow, declined
admitting him into their company; and he was obliged to withdraw his
name from the society.

When we look back upon this treatment of a man of Dr. Priestley's
character, after an interval of forty years, it cannot fail to strike
us with astonishment; and it must be owned, I think, that it reflects
an indelible stain upon that period of the history of Great Britain.
To suppose that he was in the least degree formidable to so powerful
a body as the church of England, backed as it was by the aristocracy,
by the ministry, and by the opinions of the people, is perfectly
ridiculous. His theological sentiments, indeed, were very different
from those of the established church; but so were those of Milton,
Locke, and Newton. Nay, some of the members of the church itself
entertained opinions, not indeed so decided or so openly expressed as
those of Dr. Priestley, but certainly having the same tendency. To be
satisfied of this it is only necessary to recollect the book which
Dr. Clarke published on the Trinity. Nay, some of the bishops, unless
they are very much belied, entertained opinions similar to those of
Dr. Clarke. The same observation applies to Dr. Lardner, Dr. Price,
and many others of the dissenters. Yet, the church of England never
attempted to persecute these respectable and meritorious men, nor did
they consider their opinions as at all likely to endanger the stability
of the church. Besides, Dr. Horsley had taken up the pen against Dr.
Priestley's theological opinions, and had refuted them so completely in
the opinion of the members of the church, that it was thought right to
reward his meritorious services by a bishopric.

It could hardly, therefore, be the dread of Dr. Priestley's theological
opinions that induced the clergy of the church of England to bestir
themselves against him with such alacrity. Erroneous opinions advanced
and refuted, so far from being injurious, have a powerful tendency to
support and strengthen the cause which they were meant to overturn.
Or, if there existed any latent suspicion that the refutation of
Horsley was not so complete as had been alleged, surely persecution
was not the best means of supporting weak arguments; and indeed it was
rather calculated to draw the attention of mankind to the theological
opinions of Priestley; as has in fact been the consequence.

Neither can the persecutions which Dr. Priestley was subjected to be
accounted for by his political opinions, even supposing it not to be
true, that in a free country like Great Britain, any man is at liberty
to maintain whatever theoretic opinions of government he thinks proper,
provided he be a peaceable subject and obey rigorously all the laws of
his country.

Dr. Priestley was an advocate for the perfectibility of the human
species, or at least its continually increasing tendency to
improvement--a doctrine extremely pleasing in itself, and warmly
supported by Franklin and Price; but which the wild principles of
Condorcet, Godwin, and Beddoes at last brought into discredit. This
doctrine was taught by Priestley in the outset of his Treatise on
Civil Government, first published in 1768. It is a speculation of so
very agreeable a nature, so congenial to our warmest wishes, and so
flattering to the prejudices of humanity, that one feels much pain
at being obliged to give it up. Perhaps it may be true, and I am
willing to hope so, that improvements once made are never entirely
lost, unless they are superseded by something much more advantageous,
and that therefore the knowledge of the human race, upon the whole,
is progressive. But political establishments, at least if we are to
judge from the past history of mankind, have their uniform periods of
progress and decay. Nations seem incapable of profiting by experience.
Every nation seems destined to run the same career, and the history
may be comprehended under the following heads: Poverty, liberty,
industry, wealth, power, dissipation, anarchy, destruction. We have no
example in history of a nation running through this career and again
recovering its energy and importance. Greece ran through it more than
two thousand years ago: she has been in a state of slavery ever since.
An opportunity is now at last given her of recovering her importance:
posterity will ascertain whether she will embrace it.

Dr. Priestley's short Essay on the First Principles of Civil Government
was published in 1768. In it he lays down as the foundation of his
reasoning, that "it must be understood, whether it be expressed or
not, that all people live in society for their mutual advantage; so
that the good and happiness of the members, that is the majority of
the members of any state, is the great standard by which every thing
relating to that state must be finally determined; and though it may be
supposed that a body of people may be bound by a voluntary resignation
of all their rights to a single person or to a few, it can never be
supposed that the resignation is obligatory on their posterity, because
it is manifestly contrary to the good of the whole that it should be
so." From this first principle he deduces all his political maxims.
Kings, senators, and nobles, are merely the servants of the public;
and when they abuse their power, in the people lies the right of
deposing and consequently of punishing them. He examines the expediency
of hereditary sovereignty, of hereditary rank and privileges, of the
duration of parliament, and of the right of voting, with an evident
tendency to democratical principles, though he does not express himself
very clearly on the subject.

Such were his political principles in 1768, when his book was
published. They excited no alarm and drew but little attention;
these principles he maintained ever after, or indeed he may be said
to have become more moderate instead of violent. Though he approved
of a republic in the abstract; yet, considering the prejudices and
habits of the people of Great Britain, he laid it down as a principle
that their present form of government was best suited to them. He
thought, however, that there should be a reform in parliament; and that
parliaments should be triennial instead of septennial. He was an enemy
to all violent reforms, and thought that the change ought to be brought
about gradually and peaceably. When the French revolution broke out he
took the side of the patriots, as he had done during the American war;
and he wrote a refutation of Mr. Burke's extraordinary performance.
Being a dissenter, it is needless to say that he was an advocate for
complete religious freedom. He was ever hostile to all religious
establishments, and an open enemy to the church of England.

How far these opinions were just and right this is not the place to
inquire; but that they were perfectly harmless, and that many other
persons in this country during the last century, and even at present,
have adopted similar opinions without incurring any odium whatever,
and without exciting the jealousy or even the attention of government,
is well known to every person. It comes then to be a question of some
curiosity at least, to what we are to ascribe the violent persecutions
raised against Dr. Priestley. It seems to have been owing chiefly to
the alarm caught by the clergy of the established church that their
establishment was in danger;--and, considering the ferment excited
soon after the breaking out of the French revolution, and the rage
for reform, which pervaded all ranks, the almost general alarm of the
aristocracy, at least, was not entirely without foundation. I cannot,
however, admit that there was occasion for the violent alarm caught by
Mr. Pitt and his political friends, and for the very despotic measures
which they adopted in consequence. The disease would probably have
subsided of itself, or it would have been cured by a much gentler
treatment. As Dr. Priestley was an open enemy to the establishment,
its clergy naturally conceived a prejudice against him, and this
prejudice was violently inflamed by the danger to which they thought
themselves exposed; their influence with the ministry was very great,
and Mr. Pitt and his friends naturally caught their prejudices and
opinions. Mr. Burke, too, who had changed his political principles,
and who was inflamed with the burning zeal which distinguishes all
converts, was provoked at Dr. Priestley's answer to his book on the
French revolution, and took every opportunity to inveigh against him
in the house of commons. The conduct of the French, likewise, who made
Dr. Priestley a citizen of France, and chose him a member of their
assembly, though intended as a compliment, was injurious to him in
Great Britain. It was laid hold of by his antagonists to convince the
people that he was an enemy to his country; that he had abjured his
rights as an Englishman; and that he had adopted the principles of
the hereditary enemies of Great Britain. These causes, and not his
political opinions, appear to me to account for the persecution which
was raised against him.

His sons, disgusted with this persecution of their father, had
renounced their native country and gone over to France; and, on the
breaking out of the war between this country and the French republic,
they emigrated to America. It was this circumstance, joined to the
state of insulation in which he lived, that induced Dr. Priestley,
after much consideration, to form the resolution of following his sons
and emigrating to America. He published his reasons in the preface
to a Fast-day Sermon, printed in 1794, one of the gravest and most
forcible pieces of composition I have ever read. He left England in
April, 1795, and reached New York in June. In America he was received
with much respect by persons of all ranks; and was immediately offered
the situation of professor of chemistry in the College of Philadelphia;
which, however, he declined, as his circumstances, by the liberality
of his friends in England, continued independent. He settled, finally,
in Northumberland, about 130 miles from Philadelphia, where he built
a house, and re-established his library and laboratory, as well as
circumstances permitted. Here he published a considerable number of
chemical papers, some of them under the form of pamphlets, and the rest
in the American Transactions, the New York Medical Repository, and
Nicholson's Journal of Natural Philosophy and Chemistry. Here, also,
he continued keenly engaged in theological pursuits; and published, or
republished, a great variety of books on theological subjects. Here he
lost his wife and his youngest and favourite son, who, he had flattered
himself, was to succeed him in his literary career:--and here he died,
in 1804, after having been confined only two days to bed, and but a
few hours after having arranged his literary concerns, inspected some
proof-sheets of his last theological work, and given instructions to
his son how it should be printed.

During the latter end of the presidency of Mr. Adams, the same kind of
odium which had banished Dr. Priestley from England began to prevail
in America. He was threatened with being sent out of the country
as an alien. Notwithstanding this, he declined being naturalized;
resolving, as he said, to die as he had lived, an Englishman. When his
friend Mr. Jefferson, whose political opinions coincided with his own,
became president, the odium against him wore off, and he became as much
respected as ever.

As to the character of Dr. Priestley, it is so well marked by his
life and writings, that it is difficult to conceive how it could
have been mistaken by many eminent men in this kingdom. Industry was
his great characteristic; and this quality, together with a facility
of composition, acquired, as he tells us, by a constant habit while
young of drawing out an abstract of the sermons which he had preached,
and writing a good deal in verse, enabled him to do so much: yet, he
informs us that he never was an intense student, and that his evenings
were usually passed in amusement or company. He was an early riser,
and always lighted his own fire before any one else was stirring: it
was then that he composed all his works. It is obvious, from merely
glancing into his books, that he was precipitate; and indeed, from
the way he went on thinking as he wrote, and writing only one copy,
it was impossible he could be otherwise: but, as he was perfectly
sincere and anxious to obtain the truth, he freely acknowledged his
mistakes as soon as he became sensible of them. This candour is very
visible in his philosophical speculations; but in his theological
writings it was not so much to be expected. He was generally engaged
in controversy in theology; and his antagonists were often insolent,
and almost always angry. We all know the effect of such opposition; and
need not be surprised that it operated upon Dr. Priestley, as it would
do upon any other man. By all accounts his powers of conversation
were very great, and his manners in every respect very agreeable. That
this must have been the case is obvious from the great number of his
friends, and the zeal and ardour with which they continued to serve
him, notwithstanding the obloquy under which he lay, and even the
danger that might be incurred by appearing to befriend him. As for his
moral character, even his worst enemies have been obliged to allow that
it was unexceptionable. Many of my readers will perhaps smile, when I
say that he was not only a sincere, but a zealous Christian, and would
willingly have died a martyr to the cause. Yet I think the fact is of
easy proof; and his conduct through life, and especially at his death,
affords irrefragable proofs of it. His tenets, indeed, did not coincide
with those of the majority of his countrymen; but though he rejected
many of the doctrines, he admitted the whole of the sublime morality
and the divine origin of the Christian religion; which may charitably
be deemed sufficient to constitute a true Christian. Of vanity he seems
to have possessed rather more than a usual share; but perhaps he was
deficient in pride.

His writings were exceedingly numerous, and treated of science,
theology, metaphysics, and politics. Of his theological, metaphysical,
and political writings it is not our business in this work to take any
notice. His scientific works treat of _electricity_, _optics_, and
_chemistry_. As an electrician he was respectable; as an optician,
a compiler; as a chemist, a discoverer. He wrote also a book on
perspective which I have never had an opportunity of perusing.

It is to his chemical labours that he is chiefly indebted for the
great reputation which he acquired. No man ever entered upon any
undertaking with less apparent means of success than Dr. Priestley
did on the chemical investigation of _airs_. He was unacquainted with
chemistry, excepting that he had, some years before, attended an
elementary course delivered by Mr. Turner, of Liverpool. He was not in
possession of any apparatus, nor acquainted with the method of making
chemical experiments; and his circumstances were such, that he could
neither lay out a great deal of money on experiments, nor could he
hope, without a great deal of expense, to make any material progress
in his investigations. These circumstances, which, at first sight,
seem so adverse, were, I believe, of considerable service to him, and
contributed very much to his ultimate success. The branch of chemistry
which he selected was new: an apparatus was to be invented before any
thing of importance could be effected; and, as simplicity is essential
in every apparatus, _he_ was most likely to contrive the best, whose
circumstances obliged him to attend to economical considerations.

Pneumatic chemistry had been begun by Mr. Cavendish in his valuable
paper on carbonic acid and hydrogen gases, published in the
Philosophical Transactions for 1766. The apparatus which he employed
was similar to that used about a century before by Dr. Mayow of
Oxford. Dr. Priestley contrived the apparatus still used by chemists
in pneumatic investigations; it is greatly superior to that of
Mr. Cavendish, and, indeed, as convenient as can be desired. Were
we indebted to him for nothing else than this apparatus, it would
deservedly give him high consideration as a pneumatic chemist.

His discoveries in pneumatic chemistry are so numerous, that I must
satisfy myself with a bare outline; to enumerate every thing, would
be to transcribe his three volumes, into which he digested his
discoveries. His first paper was published in 1772, and was on the
method of impregnating water with carbonic acid gas; the experiments
contained in it were the consequence of his residing near a brewery in
Leeds. This pamphlet was immediately translated into French; and, at
a meeting of the College of Physicians in London, they addressed the
Lords of the Treasury, pointing out the advantage that might result
from water impregnated with carbonic acid gas in cases of scurvy at
sea. His next essay was published in the Philosophical Transactions,
and procured him the Copleyan medal. His different volumes on air were
published in succession, while he lived with Lord Shelburne, and while
he was settled at Birmingham. They drew the attention of all Europe,
and raised the reputation of this country to a great height.

The first of his discoveries was _nitrous gas_, now called _deutoxide
of azote_, which had, indeed, been formed by Dr. Hales; but that
philosopher had not attempted to investigate its properties. Dr.
Priestley ascertained its properties with much sagacity, and almost
immediately applied it to the analysis of air. It contributed very much
to all subsequent investigations in pneumatic chemistry, and may be
said to have led to our present knowledge of the constitution of the
atmosphere.

The next great discovery was _oxygen gas_, which was made by him on
the 1st of August, 1774, by heating the red oxide of mercury, and
collecting the gaseous matter given out by it. He almost immediately
detected the remarkable property which this gas has of supporting
combustion better, and animal life longer, than the same volume of
common air; and likewise the property which it has of condensing into
red fumes when mixed with nitrous gas. Lavoisier, likewise, laid
claim to the discovery of oxygen gas; but his claim is entitled to
no attention whatever; as Dr. Priestley informs us that he prepared
this gas in M. Lavoisier's house, in Paris, and showed him the method
of procuring it in the year 1774, which is a considerable time before
the date assigned by Lavoisier for his pretended discovery. Scheele,
however, actually obtained this gas without any previous knowledge of
what Priestley had done; but the book containing this discovery was not
published till three years after Priestley's process had become known
to the public.

Dr. Priestley first made known sulphurous acid, fluosilicic acid,
muriatic acid, and ammonia in the gaseous form; and pointed out easy
methods of procuring them: he describes with exactness the most
remarkable properties of each. He likewise pointed out the existence
of carburetted hydrogen gas; though he made but few experiments to
determine its nature. His discovery of protoxide of azote affords
a beautiful example of the advantages resulting from his method of
investigation, and the sagacity which enabled him to follow out
any remarkable appearances which occurred. Carbonic oxide gas was
discovered by him while in America, and it was brought forward by him
as an incontrovertible refutation of the antiphlogistic theory.

Though he was not strictly the discoverer of hydrogen gas, yet his
experiments on it were highly interesting, and contributed essentially
to the revolution which chemistry soon after underwent. Nothing,
for example, could be more striking, than the reduction of oxide of
iron, and the disappearance of the hydrogen when the oxide is heated
sufficiently in contact with hydrogen gas. Azotic gas was known before
he began his career; but we are indebted to him for most of the
properties of it yet known. To him, also, we owe the knowledge of the
fact, that an acid is formed when electric sparks are made to pass
for some time through a given bulk of common air; a fact which led
afterwards to Mr. Cavendish's great discovery of the composition of
nitric acid.

He first discovered the great increase of bulk which takes place
when electric sparks are made to pass through ammoniacal gas--a fact
which led Berthollet to the analysis of this gas. He merely repeated
Priestley's experiment, determined the augmentation of bulk, and the
nature of the gases evolved by the action of the electricity. His
experiments on the amelioration of atmospherical air by the vegetation
of plants, on the oxygen gas given out by their leaves, and on the
respiration of animals, are not less curious and interesting.

Such is a short view of the most material facts for which chemistry
is indebted to Dr. Priestley. As a discoverer of new substances, his
name must always stand very high in the science; but as a reasoner or
theorist his position will not be so favourable. It will be observed
that almost all his researches and discoveries related to gaseous
bodies. He determined the different processes, by means of which the
different gases can be procured, the substances which yield them, and
the effects which they are capable of producing on other bodies. Of
the other departments of chemistry he could hardly be said to know any
thing. As a pneumatic chemist he stands high; as an analytical chemist
he can scarcely claim any rank whatever. In his famous experiments on
the formation of water by detonating mixtures of oxygen and hydrogen
in a copper globe, the copper was found acted upon, and a blue liquid
was obtained, the nature of which he was unable to ascertain; but Mr.
Keir, whose assistance he solicited, determined it to be a solution of
nitrate of copper in water. This formation of nitric acid induced him
to deny that water was a compound of oxygen and hydrogen. The same acid
was formed in the experiments of Mr. Cavendish; but he investigated
the circumstances of the formation, and showed that it depended upon
the presence of azotic gas in the gaseous mixture. Whenever azotic
gas is present, nitric acid is formed, and the quantity of this acid
depends upon the relative proportion of the azotic and hydrogen gases
in the mixture. When no hydrogen gas is present, nothing is formed
but nitric acid: when no azotic gas is present, nothing is formed
but water. These facts, determined by Cavendish, invalidate the
reasoning of Priestley altogether; and had he possessed the skill, like
Cavendish, to determine with sufficient accuracy the proportions of the
different gases in his mixtures, and the relative quantities of nitric
acid formed, he would have seen the inaccuracy of his own conclusions.

He was a firm believer in the existence of phlogiston; but he seems,
at least ultimately, to have adopted the view of Scheele, and many
other eminent contemporary chemists--indeed, the view of Cavendish
himself--that hydrogen gas is phlogiston in a separate and pure state.
Common air he considered as a compound of oxygen and phlogiston.
Oxygen, in his opinion, was air quite free from phlogiston, or air in
a simple and pure state; while _azotic gas_ (the other constituent of
common air) was air saturated with phlogiston. Hence he called oxygen
_dephlogisticated_, and azote _phlogisticated air_. The facts that
when common air is converted into azotic gas its bulk is diminished
about one-fifth part, and that azotic gas is lighter than common air or
oxygen gas, though not quite unknown to him, do not seem to have drawn
much of his attention. He was not accustomed to use a balance in his
experiments, nor to attend much to the alterations which took place in
the weight of bodies. Had he done so, most of his theoretical opinions
would have fallen to the ground.

When a body is allowed to burn in a given quantity of common air, it is
known that the quality of the common air is deteriorated; it becomes,
in his language, more phlogisticated. This, in his opinion, was owing
to an affinity which existed between phlogiston and air. The presence
of air is necessary to combustion, in consequence of the affinity which
it has for phlogiston. It draws phlogiston out of the burning body,
in order to combine with it. When a given bulk of air is saturated
with phlogiston, it is converted into azotic gas, or _phlogisticated
air_, as he called it; and this air, having no longer any affinity for
phlogiston, can no longer attract that principle, and consequently
combustion cannot go on in such air.

All combustible bodies, in his opinion, contain hydrogen. Of course
the metals contain it as a constituent. The calces of metals are those
bodies deprived of phlogiston. To prove the truth of this opinion, he
showed that when the oxide of iron is heated in hydrogen gas, that gas
is absorbed, while the calx is reduced to the metallic state. Finery
cinder, which he employed in these experiments, is, in his opinion,
iron not quite free from phlogiston. Hence it still retains a quantity
of hydrogen. To prove this, he mixed together finery cinder and
carbonates of lime, barytes and strontian, and exposed the mixture to a
strong heat; and by this process obtained inflammable gas in abundance.
In his opinion every inflammable gas contains hydrogen in abundance.
Hence this experiment was adduced by him as a demonstration that
hydrogen is a constituent of finery cinder.

All these processes of reasoning, which appear so plausible as Dr.
Priestley states them, vanish into nothing, when his experiments are
made, and the weights of every thing determined by means of a balance:
it is then established that a burning body becomes heavier during its
combustion, and that the surrounding air loses just as much weight as
the burning body gains. Scheele and Lavoisier showed clearly that the
loss of weight sustained by the air is owing to a quantity of oxygen
absorbed from it, and condensed in the burning body. Cruikshank first
elucidated the nature of the inflammable gas, produced by the heating
a mixture of finery cinder and carbonate of lime, or other earthy
carbonate. He found that iron filings would answer better than finery
cinder. The gas was found to contain no hydrogen, and to be in fact
a compound of oxygen and carbon. It was shown to be derived from the
carbonic acid of the earthy carbonate, which was deprived of half its
oxygen by the iron filings or finery cinder. Thus altered, it no longer
preserved its affinity for the lime, but made its escape in the gaseous
form, constituting the gas now known by the name of carbonic oxide.

Though the consequence of the Birmingham riots, which obliged Dr.
Priestley to leave England and repair to America, is deeply to be
lamented, as fixing an indelible disgrace upon the country; perhaps
it was not in reality so injurious to Dr. Priestley as may at first
sight appear. He had carried his peculiar researches nearly as far
as they could go. To arrange and methodize, and deduce from them the
legitimate consequences, required the application of a different
branch of chemical science, which he had not cultivated, and which his
characteristic rapidity, and the time of life to which he had arrived,
would have rendered it almost impossible for him to acquire. In all
probability, therefore, had he been allowed to prosecute his researches
unmolested, his reputation, instead of an increase, might have
suffered a diminution, and he might have lost that eminent situation as
a man of science which he had so long occupied.

With Dr. Priestley closes this period of the History of British
Chemistry--for Mr. Cavendish, though he had not lost his activity, had
abandoned that branch of science, and turned his attention to other
pursuits.




CHAPTER II.

OF THE PROGRESS OF PHILOSOPHICAL CHEMISTRY IN SWEDEN.


Though Sweden, partly in consequence of her scanty population, and the
consequent limited sale of books in that country, and partly from the
propensity of her writers to imitate the French, which has prevented
that originality in her poets and historians that is requisite for
acquiring much eminence--though Sweden, for these reasons, has never
reached a very high rank in literature; yet the case has been very
different in science. She has produced men of the very first eminence,
and has contributed more than her full share in almost every department
of science, and in none has she shone with greater lustre than in the
department of Chemistry. Even in the latter part of the seventeenth
century, before chemistry had, properly speaking, assumed the rank of a
science, we find Hierne in Sweden, whose name deserves to be mentioned
with respect. Moreover, in the earlier part of the eighteenth century,
Brandt, Scheffer, and Wallerius, had distinguished themselves by their
writings. Cronstedt, about the middle of the eighteenth century, may
be said to have laid the foundation of systematic mineralogy upon
chemical principles, by the publication of his System of Mineralogy.
But Bergman is entitled to the merit of being the first person who
prosecuted chemistry in Sweden on truly philosophical principles,
and raised it to that high estimation to which its importance justly
entitles it.

Torbern Bergman was born at Catherinberg, in West Gothland, on the
20th of March, 1735. His father, Barthold Bergman, was receiver of the
revenues of that district, and his mother, Sara Hägg, the daughter of
a Gotheborg merchant. A receiver of the revenues was at that time,
in Sweden, a post both disagreeable and hazardous. The creatures of
a party which had had the ascendancy in one diet, they were exposed
to the persecution of the diet next following, in which an opposite
party usually had the predominance. This circumstance induced Bergman
to advise his son to turn his attention to the professions of law or
divinity, which were at that time the most lucrative in Sweden. After
having spent the usual time at school, and acquired those branches of
learning commonly taught in Sweden, in the public schools and academies
to which Bergman was sent, he went to the University of Upsala, in the
autumn of 1752, where he was placed under the guidance of a relation,
whose province it was to superintend his studies, and direct them to
those pursuits that were likely to lead young Bergman to wealth and
distinction. Our young student showed at once a decided predilection
for mathematics, and those branches of physics which were connected
with mathematics, or depended upon them. But these were precisely
the branches of study which his relation was anxious to prevent his
indulging in. Bergman attempted at once to indulge his own inclination,
and to gratify the wishes of his relation. This obliged him to study
with a degree of ardour and perseverance which has few examples.
His mathematical and physical studies claimed the first share of his
attention; and, after having made such progress in them as would
alone have been sufficient to occupy the whole time of an ordinary
student--to satisfy his relation, Jonas Victorin, who was at that
time a _magister docens_ in Upsala, he thought it requisite to study
some law books besides, that he might be able to show that he had not
neglected his advice, nor abandoned the views which he had held out.

He was in the habit of rising to his studies every morning at four
o'clock, and he never went to bed till eleven at night. The first year
of his residence at Upsala, he had made himself master of Wolf's Logic,
of Wallerius's System of Chemistry, and of twelve books of Euclid's
Elements: for he had already studied the first book of that work in
the Gymnasium before he went to college. He likewise perused Keil's
Lectures on Astronomy, which at that time were considered as the best
introduction to physics and astronomy. His relative disapproved of his
mathematical and physical studies altogether; but, not being able to
put a stop to them, he interdicted the books, and left his young charge
merely the choice between law and divinity. Bergman got a small box
made, with a drawer, into which he put his mathematical and physical
books, and over this box he piled the law books which his relative had
urged him to study. At the time of the daily visits of his relative,
the mathematical and physical books were carefully locked up in the
drawer, and the law books spread upon the table; but no sooner was his
presence removed, than the drawer was opened, and the mathematical
studies resumed.

This incessant study; this necessity under which he found himself to
consult his own inclinations and those of his relative; this double
portion of labour, without time for relaxation, exercise, or amusement,
proved at last injurious to young Bergman's health. He fell ill, and
was obliged to leave the university and return home to his father's
house in a state of bad health. There constant and moderate exercise
was prescribed him, as the only means of restoring his health. That his
time here might not be altogether lost to him, he formed the plan of
making his walks subservient to the study of botany and entomology.

At this time Linnæus, after having surmounted obstacles which would
have crushed a man of ordinary energy, was in the height of his glory;
and was professor of botany and natural history in the University of
Upsala. His lectures were attended by crowds of students from every
country in Europe: he was enthusiastically admired and adored by
his students. This influence on the minds of his pupils was almost
unbounded; and at Upsala, every student was a natural historian.
Bergman had studied botany before he went to college, and he had
acquired a taste for entomology from the lectures of Linnæus himself.
Both of these pursuits he continued to follow after his return home
to West Gothland; and he made a collection of plants and of insects.
Grasses and mosses were the plants to which he turned the most of his
attention, and of which he collected the greatest number. But he felt
a predilection for the study of insects, which was a field much less
explored than the study of plants.

Among the insects which he collected were several not to be found in
the _Fauna Suecica_. Of these he sent specimens to Linnæus at Upsala,
who was delighted with the present. All of them were till then unknown
as Swedish insects, and several of them were quite new. The following
were the insects at this time collected by Bergman, and sent to Upsala,
as they were named by Linnæus:

  _Phalæna._   Bombyx monacha, camelina.
               Noctua Parthenias, conspicillaris.
               Perspicillaris, flavicornis, Plebeia.
               Geometra pennaria.
               Tortrix Bergmanniana, Lediana.
               Tinea Harrisella, Pedella, Punctella.
  _Tenthredo._ Vitellina, ustulata.
  _Ichneumon._ Jaculator niger.
  _Tipula._    Tremula.

When Bergman's health was re-established, he returned to Upsala with
full liberty to prosecute his studies according to his own wishes, and
to devote the whole of his time to mathematics, physics, and natural
history. His relations, finding it in vain to combat his predilections
for these studies, thought it better to allow him to indulge them.

He had made himself known to Linnæus by the collection of insects
which he had sent him from Catherinberg; and, drawn along by the
glory with which Linnæus was surrounded, and the zeal with which his
fellow-students prosecuted such studies, he devoted a great deal of
his attention to natural history. The first paper which he wrote upon
the subject contained a discovery. There was a substance observed in
some ponds not far from Upsala, to which the name of _coccus aquaticus_
was given, but its nature was unknown. Linnæus had conjectured that
it might be the _ovarium_ of some insect; but he left the point to be
determined by future observations. Bergman ascertained that it was the
ovum of a species of leech, and that it contained from ten to twelve
young animals. When he stated what he had ascertained to Linnæus, that
great naturalist refused to believe it; but Bergman satisfied him
of the truth of his discovery by actual observation. Linnæus, thus
satisfied, wrote under the paper of Bergman, _Vidi et obstupui_, and
sent it to the academy of Stockholm with this flattering panegyric. It
was printed in the Memoirs of that learned body for 1756 (p. 199), and
was the first paper of Bergman's that was committed to the press.

He continued to prosecute the study of natural history as an amusement;
though mathematics and natural philosophy occupied by far the greatest
part of his time. Various useful papers of his, connected with
entomology, appeared from time to time in the Memoirs of the Stockholm
Academy; in particular, a paper on the history of insects which attack
fruit-trees, and on the methods of guarding against their ravages: on
the method of classing these insects from the forms of their larvæ, a
time when it would be most useful for the agriculturist to know, in
order to destroy those that are hurtful: a great number of observations
on this class of animals, so various in their shape and their
organization, and so important for man to know--some of which he has
been able to overcome, while others, defended by their small size, and
powerful by their vast numbers, still continue their ravages; and which
offer so interesting a sight to the philosopher by their labours, their
manners, and their foresight.--Bergman was fond of these pursuits,
and looked back upon them in afterlife with pleasure. Long after, he
used to mention with much satisfaction, that by the use of the method
pointed out by him, no fewer than seven millions of destructive insects
were destroyed in a single garden, and during the course of a single
summer.

About the year 1757 he was appointed tutor to the only son of Count
Adolf Frederick Stackelberg, a situation which he filled greatly to the
satisfaction both of the father and son, as long as the young count
stood in need of an instructor. He took his master's degree in 1758,
choosing for the subject of his thesis on _astronomical interpolation_.
Soon after, he was appointed _magister docens_ in natural philosophy,
a situation peculiar to the University of Upsala, and constituting a
kind of assistant to the professor. For his promotion to this situation
he was obliged to M. Ferner, who saw how well qualified he was for it,
and how beneficial his labours would be to the University of Upsala. In
1761 he was appointed _adjunct_ in mathematics and physics, which, I
presume, means that he was raised to the rank of an associate with the
professor of these branches of science. In this situation it was his
business to teach these sciences to the students of Upsala, a task for
which he was exceedingly well fitted. During this period he published
various tracts on different branches of physical science, particularly
on the _rainbow_, the crepuscula, the aurora-borealis, the electrical
phenomena of Iceland spar, and of the tourmalin. We find his name
among the astronomers who observed the first transit of Venus over the
sun, in 1761, whose results deserve the greatest confidence.[1] His
observations on the electricity of the tourmalin are important. It was
he that first established the true laws that regulate these curious
phenomena.

 [1] See Phil. Trans., vol. lii. p. 227, and vol. lvi. p. 85.

During the whole of this period he had been silently studying chemistry
and mineralogy, though nobody suspected that he was engaged in any
such pursuits. But in 1767 John Gottschalk Wallerius, who had long
filled the chair of chemistry in the University of Upsala, with high
reputation, resigned his chair. Bergman immediately offered himself
as a candidate for the vacant professorship: and, to show that he
was qualified for the office, published two dissertations on the
Manufacture of Alum, which probably he had previously drawn up, and had
lying by him. Wallerius intended to resign his chair in favour of a
pupil or relation of his own, whom he had destined to succeed him. He
immediately formed a party to oppose the pretensions of Bergman; and
his party was so powerful and so malignant, that few doubted of their
success: for it was joined by all those who, despairing of equalling
the industry and reputation of Bergman, set themselves to oppose and
obstruct his success. Such men unhappily exist in all colleges, and
the more eminent a professor is, the more is he exposed to their
malignant activity. Many of those who cannot themselves rise to any
eminence, derive pleasure from the attempt to pull down the eminent
to their own level. In these attempts, however, they seldom succeed,
unless from some want of prudence and steadiness in the individual
whom they assail. Bergman's Dissertations on Alum were severely
handled by Wallerius and his party: and such was the influence of the
ex-professor, that every body thought Bergman would be crushed by him.

Fortunately, Gustavus III. of Sweden, at that time crown prince,
was chancellor of the university. He took up the cause of Bergman,
influenced, it is said, by the recommendation of Von Swab, who pledged
himself for his qualifications, and was so keen on the subject that he
pleaded his cause in person before the senate. Wallerius and his party
were of course baffled, and Bergman got the chair.

For this situation his previous studies had fitted him in a peculiar
manner. His mathematical, physical, and natural-historical knowledge,
so far from being useless, contributed to free him from prejudices, and
to emancipate him from that spirit of routine under which chemistry
had hitherto suffered. They gave to his ideas a greater degree of
precision, and made his views more correct. He saw that mathematics
and chemistry divided between them the whole extent of natural
science, and that its bounds required to be enlarged, to enable it
to embrace all the different branches of science with which it was
naturally connected, or which depended upon it. He saw the necessity
of banishing from chemistry all vague hypotheses and explanations,
and of establishing the science on the firm basis of experiment. He
was equally convinced of the necessity of reforming the nomenclature
of chemistry, and of bringing it to the same degree of precision that
characterized the language of the other branches of natural philosophy.

His first care, after getting the chair, was to make as complete a
collection as he could of mineral substances, and to arrange them in
order according to the nature of their constituents, as far as they
had been determined by experiment. To another cabinet he assigned the
Swedish minerals, ranged in a geographical manner according to the
different provinces which furnished them.

When I was at Upsala, in 1812, the first of these collections still
remained, greatly augmented by his nephew and successor, Afzelius.
But no remains existed of the geographical collection. However, there
was a very considerable collection of this kind in the apartments
of the Swedish school of mines at Stockholm, under the care of Mr.
Hjelm, which I had an opportunity of inspecting. It is not improbable
that Bergman's collection might have formed the nucleus of this. A
geographical collection of minerals, to be of much utility, should
exhibit all the different formations which exist in the kingdom: and
in a country so uniform in its nature as Sweden, the minerals of one
county are very nearly similar to those of the other counties; with
the exception of certain peculiarities derived from the mines, or from
some formations which may belong exclusively to certain parts of the
country, as, for example, the coal formations in the south corner of
Sweden, near Helsinburg, and the porphyry rocks, in Elfsdale.

Bergman attempted also to make a collection of models of the apparatus
employed in the different chemical manufactories, to be enabled to
explain these manufactures with greater clearness to his students. I
was informed by M. Ekeberg, who, in 1812, was _magister docens_ in
chemistry at Upsala, that these models were never numerous. Nor is it
likely that they should be, as Sweden cannot boast of any great number
of chemical manufactories, and as, in Bergman's time, the processes
followed in most of the chemical manufactories of Europe were kept as
secret as possible.

Thus it was Bergman's object to exhibit to his pupils specimens of all
the different substances which the earth furnishes, with the order in
which these productions are arranged on the globe--to show them the
uses made of all these different productions--how practice had preceded
theory and had succeeded in solving many chemical problems of the most
complicated nature.

His lectures are said to have been particularly valuable. He drew
around him a considerable number of pupils, who afterwards figured as
chemical discoverers themselves. Of all these Assessor Gahn, of Fahlun,
was undoubtedly the most remarkable; but Hjelm, Gadolin, the Elhuyarts,
and various other individuals, likewise distinguished themselves as
chemists.

After his appointment to the chemical chair at Upsala, the remainder
of his life passed with very little variety; his whole time was
occupied with his favourite studies, and not a year passed that he
did not publish some dissertation or other upon some more or less
important branch of chemistry. His reputation gradually extended itself
over Europe, and he was enrolled among the number of the members
of most scientific academies. Among other honourable testimonies
of the esteem in which he was held, he was elected rector of the
University of Upsala. This university is not merely a literary body,
but owns extensive estates, over which it possesses great authority,
and, having considerable control over its students, and enjoying
considerable immunities and privileges (conferred in former times as
an encouragement to learning, though, in reality, they serve only to
cramp its energies, and throw barriers in the way of its progress),
constitutes, therefore, a kind of republic in the midst of Sweden: the
professors being its chiefs. But while, in literary establishments,
all the institutions ought to have for an object to maintain peace,
and free their members from every occupation unconnected with letters,
the constitution of that university obliges its professors to attend
to things very inconsistent with their usual functions; while it
gives men of influence and ambition a desire to possess the power and
patronage, though they may not be qualified to perform the duties, of
a professor. Such temptations are very injurious to the true cause
of science; and it were to be wished, that no literary body, in any
part of the world, were possessed of such powers and privileges. When
Bergman was rector, the university was divided into two great parties,
the one consisting of the theological and law faculties, and the other
of the scientific professors. Bergman's object was to preserve peace
and agreement between these two parties, and to convince them that it
was the interest of all to unite for the good of the university and the
promotion of letters. The period of his magistracy is remarkable in the
annals of the university for the small number of deliberations, and the
little business recorded in the registers; and for the good sense and
good behaviour of the students. The students in Upsala are numerous,
and most of them are young men. They had been accustomed frequently to
brave or elude the severity of the regulations; but during Bergman's
rectorship they were restrained effectually by their respect for his
genius, and their admiration of his character and conduct.

When the reputation of Bergman was at its height, in the year 1776,
Frederick the Great of Prussia formed the wish to attach him to the
Academy of Sciences of Berlin, and made him offers of such a nature
that our professor hesitated for a short time as to whether he ought
not to accept them. His health had been injured by the assiduity
with which he had devoted himself to the double duty of teaching and
experimenting. He might look for an alleviation of his ailments, if
not a complete recovery, in the milder climate of Prussia, and he
would be able to devote himself entirely to his academical duties; but
other considerations prevented him from acceding to this proposal,
tempting as it was. The King of Sweden had been his benefactor, and it
was intimated to him that his leaving the kingdom would afflict that
monarch. This information induced him, without further hesitation,
to refuse the proposals of the King of Prussia. He requested of the
king, his master, not to make him lose the merit of his sacrifice
by augmenting his income; but to this demand the King of Sweden very
properly refused to accede.

In the year 1771, Professor Bergman married a widow lady, Margaretha
Catharina Trast, daughter of a clergyman in the neighbourhood of
Upsala. By her he had two sons; but both of them died when infants.
This lady survived her husband. The King of Sweden settled on her an
annuity of 200 rix dollars, on condition that she gave up the library
and apparatus of her late husband to the Royal Society of Upsala.

Bergman's health had been always delicate; indeed he seems never to
have completely recovered the effects of his first year's too intense
study at Upsala. He struggled on, however, with his ailments; and, by
way of relaxation, was accustomed sometimes, in summer, to repair to
the waters of Medevi--a celebrated mineral spring in Sweden, situated
near the banks of the great inland lake, Wetter. One of these visits
seems to have restored him to health for the time. But his malady
returned in 1784 with redoubled violence. He was afflicted with
hemorrhoids, and his daily loss of blood amounted to about six ounces.
This constant drain soon exhausted him, and on the 8th of July, 1784,
he died at the baths of Medevi, to which he had repaired in hopes of
again benefiting by these waters.

The different tracts which he published, as they have been enumerated
by Hjelm, who gave an interesting account of Bergman to the Stockholm
Academy in the year 1785, amount to 106. They have been all collected
into six octavo volumes entitled "Opuscula Torberni Bergman Physica et
Chemica"--with the exception of his notes on Scheffer, his Sciagraphia,
and his chapter on Physical Geography, which was translated into
French, and published in the Journal des Mines (vol. iii. No. 15, p.
55). His Sciagraphia, which is an attempt to arrange minerals according
to their composition, was translated into English by Dr. Withering.
His notes on Scheffer were interspersed in an edition of the "Chemiske
Föreläsningar" of that chemist, published in 1774, which he seems to
have employed as a text-book in his lectures: or, at all events, the
work was published for the use of the students of chemistry at Upsala.
There was a new edition of it published, after Bergman's death, in the
year 1796, to which are appended Bergman's Tables of Affinities.

The most important of Bergman's chemical papers were collected by
himself, and constitute the three first volumes of his Opuscula. The
three last volumes of that work were published after his death. The
fourth volume was published at Leipsic, in 1787, by Hebenstreit, and
contains the rest of his chemical papers. The fifth volume was given
to the world in 1788, by the same editor. It contains three chemical
papers, and the rest of it is made up with papers on natural history,
electricity, and other branches of physics, which Bergman had published
in the earlier part of his life. The same indefatigable editor
published the sixth volume in 1790. It contains three astronomical
papers, two chemical, and a long paper on the means of preventing any
injurious effects from lightning. This was an oration, delivered before
the Royal Academy of Sciences of Stockholm, in 1764, probably at the
time of his admission into the academy.

It would serve little purpose in the present state of chemical
knowledge, to give a minute analysis of Bergman's papers. To judge
of their value, it would be necessary to compare them, not with our
present chemical knowledge, but with the state of the science when
his papers were published. A very short general view of his labours
will be sufficient to convey an idea of the benefits which the science
derived from them.

1. His first paper, entitled "On the Aerial Acid," that is, _carbonic
acid_, was published in 1774. In it he gives the properties of this
substance in considerable detail, shows that it possesses acid
qualities, and that it is capable of combining with the bases, and
forming salts. What is very extraordinary, in giving an account of
carbonate of lime and carbonate of magnesia, he never mentions the name
of Dr. Black; though it is very unlikely that a controversy, which had
for years occupied the attention of chemists, should have been unknown
to him. Mr. Cavendish's name never once appears in the whole paper;
though that philosopher had preceded him by seven or eight years. He
informs us, that he had made known his opinions respecting the nature
of this substance, to various foreign correspondents, among others
to Dr. Priestley, as early as the year 1770, and that Dr. Priestley
had mentioned his views on the subject, in a paper inserted in the
Philosophical Transactions for 1772. Bergman found the specific gravity
of carbonic acid gas rather higher than 1·5, that of air being 1.
His result is not far from the truth. He obtained his gas, by mixing
calcareous spar with dilute sulphuric acid. He shows that this gas
has a sour taste, that it reddens the infusion of litmus, and that
it combines with bases. He gives figures of the apparatus which he
used. This apparatus demands attention. Though far inferior to the
contrivances of Priestley, it answered pretty well, enabling him to
collect the gas, and examine its properties.

It is unnecessary to enter into any further details respecting this
paper. Whoever will take the trouble to compare it with Cavendish's
paper on the same subject, will find that he had been anticipated by
that philosopher in a great many of his most important facts. Under
these circumstances, I consider as singular his not taking any notice
of Cavendish's previous labours.

2. His next paper, "On the Analyses of Mineral Waters," was first
published in 1778, being the subject of a thesis, supported by J.
P. Scharenberg. This dissertation, which is of great length, is
entitled to much praise. He lays therein the foundation of the mode of
analyzing waters, such as is followed at present. He points out the
use of different reagents, for detecting the presence of the various
constituents in mineral water, and then shows how the quantity of each
is to be determined. It would be doing great injustice to Bergman, to
compare his analyses with those of any modern experimenter. At that
time, the science was not in possession of any accurate analyses of
the neutral salts, which exist in mineral waters. Bergman undertook
these necessary analyses, without which, the determination of the
saline constituents of mineral waters was out of the question. His
determinations were not indeed accurate, but they were so much
better than those that preceded them, and Bergman's character as an
experimenter stood so high, that they were long referred to as a
standard by chemists. The first attempt to correct them was by Kirwan.
But Bergman's superior reputation as a chemist enabled his results
still to keep their ground, till his character for accuracy was finally
destroyed by the very accurate experiments which the discovery of
the atomic theory rendered it necessary to make. These, when once
they became generally known, were of course preferred, and Bergman's
analyses were laid aside.

It is a curious and humiliating fact, as it shows how much chemical
reputation depends upon situation, or accidental circumstances, that
Wenzel had, in 1766, in his book on _affinity_, published much more
accurate analyses of all these salts, than Bergman's--analyses indeed
which were almost perfectly correct, and which have scarcely been
surpassed, by the most careful ones of the present day. Yet these
admirable experiments scarcely drew the attention of chemists; while
the very inferior ones of Bergman were held up as models of perfection.

3. Bergman, not satisfied with pointing out the mode of analyzing
mineral waters, attempted to imitate them artificially by chemical
processes, and published two essays on the subject; in the first he
showed the processes by which cold mineral waters might be imitated,
and in the other, the mode of imitating hot mineral waters. The attempt
was valuable, and served to extend greatly the chemical knowledge of
mineral waters, and of the salts which they contain; but it was made
at too early a period of the analytical art, to approach perfection.
A similar remark applies to his analysis of sea-water. The water
examined was brought by Sparmann from a depth of eighty fathoms, near
the latitude of the Canaries: Bergman found in it only common salt,
muriate of magnesia, and sulphate of lime. His not having discovered
the presence of sulphate of magnesia is a sufficient proof of the
imperfection of his analytical methods; the other constituents exist
in such small quantity in sea-water that they might easily have been
overlooked, but the quantity of sulphate of magnesia in sea-water is
considerable.

4. I shall pass over the paper on oxalic acid, which constituted the
subject of a thesis, supported in 1776, by John Afzelius Arfvedson.
It is now known that oxalic acid was discovered by Scheele, not by
Bergman. It is impossible to say how many of the numerous facts
stated in this thesis were ascertained by Scheele, and how many
by Afzelius. For, as Afzelius was already a _magister docens_ in
chemistry, there can be little doubt that he would himself ascertain
the facts which were to constitute the foundation of his thesis. It
is indeed now known that Bergman himself intrusted all the details of
his experiments to his pupils. He was the contriver, while his pupils
executed his plans. That Scheele has nowhere laid claim to a discovery
of so much importance as that of oxalic acid, and that he allowed
Bergman peaceably to bear away the whole credit, constitutes one of
the most remarkable facts in the history of chemistry. Moreover, while
it reflects so much credit on Scheele for modesty and forbearance,
it seems to bear a little hard upon the character of Bergman. When
he published the essay in the first volume of his Opuscula, in 1779,
why did he not in a note inform the world that Scheele was the
true discoverer of this acid? Why did he allow the discovery to be
universally assigned to him, without ever mentioning the true state of
the case? All this appeared so contrary to the character of Bergman,
that I was disposed to doubt the truth of the statement, that Scheele
was the discoverer of oxalic acid. When I was at Fahlun, in the year
1812, I took an opportunity of putting the question to Assessor Gahn,
who had been the intimate friend of Scheele, and the pupil, and
afterwards the friend of Bergman. He assured me that Scheele really was
the discoverer of oxalic acid, and ascribed the omission of Bergman to
inadvertence. Assessor Gahn showed me a volume of Scheele's letters
to him, which he had bound up: they contained the history of all his
chemical labours. I have little doubt that an account of oxalic acid
would be found in these letters. If the son of Assessor Gahn, in whose
possession these letters must now be, would take the trouble to inspect
the volume in question, and to publish any notices respecting this acid
which they may contain, he would confer an important favour on every
person interested in the history of chemistry.

5. The dissertation on the manufacture of alum has been mentioned
before. Bergman shows himself well acquainted with the processes
followed, at least in Sweden, for making alum. He had no notion of
the true constitution of alum; nor was that to be expected, as the
discovery was thereby years later in being made. He thought that the
reason why alum leys did not crystallize well was, that they contained
an excess of acid, and that the addition of potash gave them the
property of crystallizing readily, merely by saturating that excess
of acid. Alum is a double salt, composed of three integrant particles
of sulphate of alumina, and one integrant particle of sulphate of
potash, or sulphate of ammonia. In some cases, the alum ore contains
all the requisite ingredients. This is the case with the ore at Tolfa,
in the neighbourhood of Rome. It seems, also, to be the case with
respect to some of the alum ores in Sweden; particularly at Hœnsœter
on Kinnekulle, in West Gothland, which I visited in 1812. If any
confidence can be put in the statements of the manager of those works,
no alkaline salt whatever is added; at least, I understood him to say
so when I put the question.

6. In his dissertation on tartar-emetic, he gives an interesting
historical account of this salt and its uses. His notions respecting
the antimonial preparations best fitted to form it, are not accurate:
nor, indeed, could they be expected to be so, till the nature and
properties of the different oxides of antimony were accurately
known. Antimony forms three _oxides_: now it is the protoxide alone
that is useful in medicine, and that enters into the composition
of tartar-emetic; the other two oxides are inert, or nearly so.
Bergman was aware that tartar-emetic is a double salt, and that its
constituents are tartaric acid, potash, and oxide of antimony; but it
was not possible, in 1773, when his dissertation was published, to have
determined the true constituents of this salt by analysis.

7. Bergman's paper on magnesia was also a thesis defended in 1775,
by Charles Norell, of West Gothland, who in all probability made the
experiments described in the essay. In the introduction we have a
history of the discovery of magnesia, and he mentions Dr. Black as the
person who first accurately made out its peculiar chemical characters,
and demonstrated that it differs from lime. This essay contains a
pretty full and accurate account of the salts of magnesia, considering
the state of chemistry at the time when it was published. There is no
attempt to analyze any of the magnesian salts; but, in his treatise on
the analysis of mineral waters, he had stated the quantity of magnesia
contained in one hundred parts of several of them.

8. His paper on the _shapes of crystals_, published in 1773, contains
the germ of the whole theory of crystallization afterwards developed by
M. Hauy. He shows how, from a very simple primary form of a mineral,
other shapes may proceed, which seem to have no connexion with, or
resemblance to the primary form. His view of the subject, so far as
it goes, is the very same afterwards adopted by Hauy: and, what is
very curious, Hauy and Bergman formed their theory from the very
same crystalline shape of calcareous spar--from which, by mechanical
divisions, the same rhombic nucleus was extracted by both. Nothing
prevented Bergman from anticipating Hauy but a sufficient quantity of
crystals to apply his theory to.[2]

 [2] I shall mention afterwards that the real discoverer of this fact
 was Assessor Gahn, of Fahlun.

9. In his paper on silica he gives us a history of the progress of
chemical knowledge respecting this substance. Its nature was first
accurately pointed out by Pott; though Glauber, and before him Van
Helmont, were acquainted with the _liquor silicus_, or the combination
of silica and potash, which is soluble in water. Bergman gives a
detailed account of its properties; but he does not suspect it to
possess acid properties. This great discovery, which has thrown a
new light upon mineral bodies, and shown them all to be chemical
combinations, was reserved for Mr. Smithson.

10. Bergman's experiments on the precious stones constitute the first
rudiments of the method of analyzing stony bodies. His processes are
very imperfect, and his apparatus but ill adapted to the purpose. We
need not be surprised, therefore, that the results of his analyses
are extremely wide of the truth. Yet, if we study his processes, we
shall find in them the rudiments of the very methods which we follow
at present. The superiority of the modern analyses over those of
Bergman must in a great measure be ascribed to the platinum vessels
which we now employ, and to the superior purity of the substances which
we use as reagents in our analyses. The methods, too, are simplified
and perfected. But we must not forget that this paper of Bergman's,
imperfect as it is, constitutes the commencement of the art, and that
fully as much genius and invention may be requisite to contrive the
first rude processes, how imperfect soever they may be, as are required
to bring these processes when once invented to a state of comparative
perfection. The great step in analyzing minerals is to render them
soluble in acids. Bergman first thought of the method for accomplishing
this which is still followed, namely, fusing them or heating them to
redness with an alkali or alkaline carbonate.

11. The paper on fulminating gold goes a great way to explain the
nature of that curious compound. He describes the properties of this
substance, and the effects of alkaline and acid bodies on it. He
shows that it cannot be formed without ammonia, and infers from his
experiments that it is a compound of oxide of gold and ammonia. He
explains the fulmination by the elastic fluid suddenly generated by the
decomposition of the ammonia.

12. The papers on platinum, carbonate of iron, nickel, arsenic, and
zinc, do not require many remarks. They add considerably to the
knowledge which chemists at that time possessed of these bodies; though
the modes of analysis are not such as would be approved of by a modern
chemist; nor were the results obtained possessed of much precision.

13. The Essay on the Analysis of Metallic Ores by the wet way, or by
solution, constitutes the first attempt to establish a regular method
of analyzing metallic ores. The processes are all imperfect, as might
be expected from the then existing state of analytical chemistry, and
the imperfect knowledge possessed, of the different metallic ores.
But this essay constituted a first beginning, for which the author is
entitled to great praise. The subject was taken up by Klaproth, and
speedily brought to a great degree of improvement by the labours of
modern chemists.

14. The experiments on the way in which minerals behave before the
blowpipe, which Bergman published, were made at Bergman's request
by Assessor Gahn, of Fahlun, who was then his pupil. They constitute
the first results obtained by that very ingenious and amiable man. He
afterwards continued the investigation, and added many improvements,
simplifying the reagents and the manner of using them. But he was too
indolent a man to commit the results of his investigations to writing.
Berzelius, however, had the good sense to see the importance of the
facts which Gahn had ascertained. He committed them to writing, and
published them for the use of mineralogists. They constitute the book
entitled "Berzelius on the Blowpipe," which has been translated into
English.

15. The object of the Essay on Metallic Precipitates is to determine
the quantity of phlogiston which each metal contains, deduced from
the quantity of one metal necessary to precipitate a given weight of
another. The experiments are obviously made with little accuracy:
indeed they are not susceptible of very great precision. Lavoisier
afterwards made use of the same method to determine the quantity of
oxygen in the different metallic oxides; but his results were not more
successful than those of Bergman.

16. Bergman's paper on iron is one of the most important in his whole
works, and contributed very materially to advance the knowledge of
the cause of the difference between iron and steel. He employed
his pupils to collect specimens of iron from the different Swedish
forges, and gave them directions how to select the proper pieces.
All these specimens, to the number of eighty-nine, he subjected to a
chemical examination, by dissolving them in dilute sulphuric acid. He
measured the volume of hydrogen gas, which he obtained by dissolving
a given weight of each, and noted the quantity and the nature of the
undissolved residue. The general result of the whole investigation
was that pure malleable iron yielded most hydrogen gas; steel less,
and cast-iron least of all. Pure malleable iron left the smallest
quantity of insoluble matter, steel a greater quantity, and cast-iron
the greatest of all. From these experiments he drew conclusions with
respect to the difference between iron, steel, and cast-iron. Nothing
more was necessary than to apply the antiphlogistic theory to these
experiments, (as was done soon after by the French chemists,) in
order to draw important conclusions respecting the nature of these
bodies. Iron is a simple body; steel is a compound of iron and carbon;
and cast-iron of iron and a still greater proportion of carbon. The
defective part of the experiments of Bergman in this important paper
is his method of determining the quantity of _manganese_ in iron. In
some specimens he makes the manganese amount to considerably more than
a third part of the weight of the whole. Now we know that a mixture of
two parts iron and one part manganese is brittle and useless. We are
sure, therefore, that no malleable iron whatever can contain any such
proportion of manganese. The fact is, that Bergman's mode of separating
manganese from iron was defective. What he considered as manganese was
chiefly, and might be in many cases altogether, oxide of iron. Many
years elapsed before a good process for separating iron from manganese
was discovered.

17. Bergman's experiments to ascertain the cause of the brittleness of
cold-short iron need not occupy much of our attention. He extracted
from it a white powder, by dissolving the cold-short iron in dilute
sulphuric acid. This white powder he succeeded in reducing to the state
of a white brittle metal, by fusing it with a flux and charcoal.
Klaproth soon after ascertained that this metal was a phosphuret of
iron, and that the white powder was a phosphate of iron: and Scheele,
with his usual sagacity, hit on a method of analyzing this phosphate,
and thus demonstrating its nature. Thus Bergman's experiments led to
the knowledge of the fact that cold-short iron owes its brittleness to
a quantity of phosphorus which it contains. It ought to be mentioned
that Meyer, of Stettin, ascertained the same fact, and made it known to
chemists at about the same time with Bergman.

18. The dissertation on the products of volcanoes, first published in
1777, is one of the most striking examples of the sagacity of Bergman
which we possess. He takes a view of all the substances certainly known
to have been thrown out of volcanoes, attempts to subject them to a
chemical analysis, and compares them with the basalt, and greenstone or
trap-rocks, the origin of which constituted at that time a keen matter
of dispute among geologists. He shows the identity between lavas and
basalt and greenstone, and therefore infers the identity of formation.
This is obviously the true mode of proceeding, and, had it been adopted
at an earlier period, many of those disputes respecting the nature of
trap-rocks, which occupied geologists for so long a period, would never
have been agitated; or, at least, would have been speedily decided. The
whole dissertation is filled with valuable matter, still well entitled
to the attention of geologists. His observations on _zeolites_, which
he considered as unconnected with volcanic products, were very natural
at the time when he wrote: though the subsequent experiments of Sir
James Hall, and Mr. Gregory Watt, and, above all, an accurate attention
to the scoriæ from different smelting-houses, have thrown a new light
on the subject, and have shown the way in which zeolitic crystals
might easily have been formed in melted lava, provided circumstances
were favourable. In fact, we find abundant cavities in real lava from
Vesuvius, filled with zeolitic crystals.

19. The last of the labours of Bergman which I shall notice here is
his Essay on Elective Attractions, which was originally published
in 1775, but was much augmented and improved in the third volume of
his Opuscula, published in 1783. An English translation of this last
edition of the Essay was made by Dr. Beddoes, and was long familiar to
the British chemical world. The object of this essay was to elucidate
and explain the nature of chemical affinity, and to account for all the
apparent anomalies that had been observed. He laid it down as a first
principle, that all bodies capable of combining chemically with each
other, have an attraction for each other, and that this attraction is
a definite and fixed force which may be represented by a number. Now
the bodies which have the property of uniting together are chiefly the
acids and the alkalies, or bases. Every acid has an attraction for each
of the alkalies or bases; but the force of this attraction differs in
each. Some bases have a strong attraction for acids, and others a weak;
but the attractive force of each may be expressed by numbers.

Now, suppose that an acid _a_ is united with a base _m_ with a certain
force, if we mix the compound _a m_ with a certain quantity of the
base _n_, which has a stronger attraction for _a_ than _m_ has, the
consequence will be, that _a_ will leave _m_ and unite with _n_;--_n_
having a stronger attraction for _a_ than _m_ has, will disengage it
and take its place. In consequence of this property, which Bergman
considered as the foundation of the whole of the science, the
strength of affinity of one body for another is determined by these
decompositions and combinations. If _n_ has a stronger affinity for
_a_ than _m_ has, then if we mix together _a_, _m_, and _n_ in the
requisite proportions, _a_ and _n_ will unite together, leaving _m_
uncombined: or if we mix _n_ with the compound _a m_, _m_ will be
disengaged. Tables, therefore, may be drawn up, exhibiting the strength
of these affinities. At the top of a column is put the name of an
_acid_ or a _base_, and below it are put the names of all the _bases_
or _acids_ in the order of their affinity. The following little table
will exhibit a specimen of these columns:

  _Sulphuric Acid._
  Barytes
  Strontian
  Potash
  Soda
  Lime
  Magnesia.

Here sulphuric acid is the substance placed at the head of the column,
and under it are the names of the bases capable of uniting with it in
the order of their affinity. Barytes, which is highest up, has the
strongest affinity, and magnesia, which is lowest down, has the weakest
affinity. If sulphuric acid and magnesia were combined together, all
the bases whose names occur in the table above magnesia would be able
to separate the sulphuric acid from it. Potash would be disengaged from
sulphuric acid by barytes and strontian, but not by soda, lime, and
magnesia.

Such tables then exhibited to the eye the strength of affinity of all
the different bodies that are capable of uniting with one and the same
substance, and the order in which decompositions are effected. Bergman
drew up tables of affinity according to these views in fifty-nine
columns. Each column contained the name of a particular substance,
and under it was arranged all the bodies capable of uniting with it,
each in the order of its affinity. Now bodies may be made to unite,
either by mixing them together, and then exposing them to heat, or
by dissolving them in water and mixing the respective solutions
together. The first of these ways is usually called the _dry way_,
the second the _moist way_. The order of decompositions often varies
with the mode employed. On this account, Bergman divided each of his
fifty-nine columns into two. In the first, he exhibited the order of
decompositions in the moist way, in the second in the dry. He explained
also the cases of double decomposition, by means of these unvarying
forces acting together or opposing each other--and gave sixty-four
cases of such double decompositions.

These views of Bergman's were immediately acceded to by the chemical
world, and continued to regulate their processes till Berthollet
published his Chemical Statics in 1802. He there called in question the
whole doctrine of Bergman, and endeavoured to establish one of the very
opposite kind. I shall have occasion to return to the subject when I
come to give an account of the services which Berthollet conferred upon
chemistry.

I have already observed, that we are under obligations to Bergman, not
merely for the improvements which he himself introduced into chemistry,
but for the pupils whom he educated as chemists, and the discoveries
which were made by those persons, whose exertions he stimulated and
encouraged. Among those individuals, whose chemical discoveries were
chiefly made known to the world by his means, was Scheele, certainly
one of the most extraordinary men, and most sagacious and industrious
chemists that ever existed.

Charles William Scheele was born on the 19th of December, 1742, at
Stralsund, the capital of Swedish Pomerania, where his father was a
tradesman. He received the first part of his education at a private
academy in Stralsund, and was afterwards removed to a public school.
At a very early period he expressed a strong desire to study pharmacy,
and obtained his father's consent to make choice of this profession.
He was accordingly bound an apprentice for six years to Mr. Bouch, an
apothecary in Gotheborg, and after his time was out, he remained with
him still, two years longer.

It was here that he laid the groundwork of all his future celebrity,
as we are informed by Mr. Grunberg, who was his fellow-apprentice,
and afterwards settled as an apothecary in Stralsund. He was at that
time very reserved and serious, but uncommonly diligent. He attended
minutely to all the processes, reflected upon them while alone, and
studied the writings of Neumann, Lemery, Kunkel, and Stahl, with
indefatigable industry. He likewise exercised himself a good deal
in drawing and painting, and acquired some proficiency in these
accomplishments without a master. Kunkel's Laboratorium was his
favourite book, and he was in the habit of repeating experiments out of
it secretly during the night-time. On one occasion, as he was employed
in making pyrophorus, his fellow-apprentice was malicious enough to
put a quantity of fulminating powder into the mixture. The consequence
was a violent explosion, which, as it took place in the night, threw
the whole family into confusion, and brought a very severe rebuke
upon our young chemist. But this did not put a stop to his industry,
which he pursued so constantly and judiciously, that, by the time his
apprenticeship was ended, there were very few chemists indeed who
excelled him in knowledge and practical skill. His fellow-apprentice,
Mr. Grunberg, wrote to him in 1774, requesting to know by what means he
had become such a proficient in chemistry, and received the following
answer: "I look upon you, my dear friend, as my first instructor,
and as the author of all I know on the subject, in consequence of
your advising me to read Neumann's Chemistry. The perusal of this
book first gave me a taste for experimenting, myself; and I very well
remember, that upon mixing some oil of cloves and smoking spirit of
nitre together, they took fire. However, I kept this matter secret.
I have also before my eyes the unfortunate experiment which I made
with pyrophorus. Such accidents only served to increase my passion for
making experiments."

In 1765 Scheele went to Malmo, to the house of an apothecary, called
Mr. Kalstrom. After spending two years in that place, he went to
Stockholm, to superintend the apothecary's shop of Mr. Scharenberg. In
1773 he exchanged this situation for another at Upsala, in the house of
Mr. Loock. It was here that he accidentally formed an acquaintance with
Assessor Gahn, of Fahlun, who was at that time a student at Upsala, and
a zealous chemist. Mr. Gahn happening to be one day in the shop of Mr.
Loock, that gentleman mentioned to him a circumstance which had lately
occurred to him, and of which he was anxious to obtain an explanation.
If a quantity of saltpetre be put into a crucible and raised to such a
temperature as shall not merely melt it, but occasion an agitation in
it like boiling, and if, after a certain time, the crucible be taken
out of the fire and allowed to cool, the saltpetre still continues
neutral; but its properties are altered: for, if distilled vinegar be
poured upon it, red fumes are given out, while vinegar produces no
effect upon the saltpetre before it has been thus heated. Mr. Loock
wished from Gahn an explanation of the cause of this phenomenon: Gahn
was unable to explain it; but promised to put the question to Professor
Bergman. He did so accordingly, but Bergman was as unable to find an
explanation as himself. On returning a few days after to Mr. Loock's
shop, Gahn was informed that there was a young man in the shop who had
given an explanation of the phenomenon. This young man was Scheele, who
had informed Mr. Loock that there were two species of acids confounded
under the name of _spirit of nitre_; what we at present call _nitric_
and _hyponitrous_ acids. Nitric acid has a stronger affinity for potash
than vinegar has; but hyponitrous acid has a weaker. The heat of the
fire changes the _nitric_ acid of the saltpetre to _hyponitrous_: hence
the phenomenon.

Gahn was delighted with the information, and immediately formed an
acquaintance with Scheele, which soon ripened into friendship. When he
informed Bergman of Scheele's explanation, the professor was equally
delighted, and expressed an eager desire to be made acquainted with
Scheele; but when Gahn mentioned the circumstance to Scheele, and
offered to introduce him to Bergman, our young chemist rejected the
proposal with strong feelings of dislike.

It seems, that while Scheele was in Stockholm, he had made experiments
on cream of tartar, and had succeeded in separating from it tartaric
acid, in a state of purity. He had also determined a number of the
properties of tartaric acid, and examined several of the tartrates. He
drew up an account of these results, and sent it to Bergman. Bergman,
seeing a paper subscribed by the name of a person who was unknown to
him, laid it aside without looking at it, and forgot it altogether.
Scheele was very much provoked at this contemptuous and unmerited
treatment. He drew up another account of his experiments and gave it to
Retzius, who sent it to the Stockholm Academy of Sciences (with some
additions of his own), in whose Memoirs it was published in the year
1770.[3] It cost Assessor Gahn considerable trouble to satisfy Scheele
that Bergman's conduct was merely the result of inadvertence, and that
he had no intention whatever of treating him either with contempt or
neglect. After much entreaty, he prevailed upon Scheele to allow him
to introduce him to the professor of chemistry. The introduction took
place accordingly, and ever after Bergman and Scheele continued steady
friends--Bergman facilitating the researches of Scheele by every means
in his power.

 [3] Konig. Vetensk. Acad. Handl. 1770, p. 207.

So high did the character of Scheele speedily rise in Upsala, that when
the Duke of Sudermania visited the university soon after, in company
with Prince Henry of Prussia, Scheele was appointed by the university
to exhibit some chemical processes before him. He fulfilled his charge,
and performed in different furnaces several curious and striking
experiments. Prince Henry asked him various questions, and expressed
satisfaction at the answers given. He was particularly pleased
when informed that he was a native of Stralsund. These two princes
afterwards stated to the professors that they would take it as a favour
if Scheele could have free access to the laboratory of the university
whenever he wished to make experiments.

In the year 1775, on the death of Mr. Popler, apothecary at Köping (a
small place on the north side of the lake Mæler), he was appointed by
the Medical College _provisor_ of the apothecary's shop. In Sweden all
the apothecaries are under the control of the Medical College, and no
one can open a shop without undergoing an examination and receiving
licence from that learned body. In the course of the examinations
which he was obliged to undergo, Scheele gave great proofs of his
abilities, and obtained the appointment. In 1777 the widow sold him
the shop and business, according to a written agreement made between
them; but they still continued housekeeping at their joint expense. He
had already distinguished himself by his discovery of fluoric acid,
and by his admirable paper on manganese. It is said, too, that it was
he who made the experiments on carbonic acid gas, which constitute the
substance of Bergman's paper on the subject, and which confirmed and
established Bergman's idea that it was an acid. At Köping he continued
his researches with unremitting perseverance, and made more discoveries
than all the chemists of his time united together. It was here that he
made the experiments on air and fire, which constitute the materials of
his celebrated work on these subjects. The theory which he formed was
indeed erroneous; but the numerous discoveries which the book contains
must always excite the admiration of every chemist. His discovery of
oxygen gas had been anticipated by Priestley; but his analysis of
atmospheric air was new and satisfactory--was peculiarly his own. The
processes by means of which he procured oxygen gas were also new,
simple, and easy, and are still followed by chemists in general. During
his residence at Köping he published a great number of chemical papers,
and every one of them contained a discovery. The whole of his time was
devoted to chemical investigations. Every action of his life had a
tendency to forward the advancement of his favourite science; all his
thoughts were turned to the same object; all his letters were devoted
to chemical observations and chemical discussions. Crell's Annals was
at that time the chief periodical work on chemistry in Germany. He got
the numbers regularly as they were published, and was one of Crell's
most constant and most valuable correspondents. Every one of his
letters published in that work either contains some new chemical fact,
or exposes the errors and mistakes of some one or other of Crell's
numerous correspondents.

Scheele's outward appearance was by no means prepossessing. He seldom
joined in the usual conversations and amusements of society, having
neither leisure nor inclination for them. What little time he had to
spare from the hurry of his profession was always employed in making
experiments. It was only when he received visits from his friends,
with whom he could converse on his favourite science, that he indulged
himself in a little relaxation. For such intimate friends he had
a sincere affection. This regard was extended to all the zealous
cultivators of chemistry in every part of the world, whether personally
known to him or not. He kept up a correspondence with several; though
this correspondence was much limited by his ignorance of all languages
except German; for at least he could not write fluently in any other
language. His chemical papers were always written in German, and
translated into Swedish, before they were inserted in the Memoirs of
the Stockholm Academy, where most of them appeared.

He was kind and affable to all. Before he adopted an opinion in
science, he reflected maturely on it; but, after he had once embraced
it, his opinions were not easily shaken. However, he did not hesitate
to give up an opinion as soon as it had been proved to be erroneous.
Thus, he entirely renounced the notion which he once entertained that
_silica_ is a compound of _water_ and _fluoric acid_; because it was
demonstrated, by Meyer and others, that this _silica_ was derived
from the glass vessels in which the fluoric acid was prepared; that
these glass vessels were speedily corroded into holes; and that, if
fluoric acid was prepared in metallic vessels, and not allowed to come
in contact with glass or any substance containing silica, it might be
mixed with water without any deposition of silica whatever.

It appears also by a letter of his, published in Crell's Annals, that
he was satisfied of the accuracy of Mr. Cavendish's experiments,
showing that water was a compound of oxygen and hydrogen gases, and
of Lavoisier's repetition of them. He attempted to reconcile this
fact with his own notion, that heat is a compound of oxygen and
hydrogen. But his arguments on that subject, though ingenious, are not
satisfactory; and there is little doubt that if he had lived somewhat
longer, and had been able to repeat his own experiments, and compare
them with those of Cavendish and Lavoisier, he would have given up
his own theory and adopted that of Lavoisier, or, at any rate, the
explanation of Cavendish, which, being more conformable to his own
preconceived notions, might have been embraced by him in preference.

It is said by Dr. Crell that Scheele was invited over to England, with
an offer of an easy and advantageous situation; but that his love of
quiet and retirement, and his partiality for Sweden, where he had
spent the greatest part of his life, threw difficulties in the way
of these overtures, and that a change in the English ministry put a
stop to them for the time. The invitation, Crell says, was renewed
in 1786, with the offer of a salary of 300_l._ a-year; but Scheele's
death put a final stop to it. I have very great doubts about the truth
of this statement; and, many years ago, during the lifetime of Sir
Joseph Banks, Mr. Cavendish, and Mr. Kirwan, I made inquiry about the
circumstance; but none of the chemists in Great Britain, who were at
that time numerous and highly respectable, had ever heard of any such
negotiation. I am utterly at a loss to conceive what one individual
in any of the ministries of George III. was either acquainted with
the science of chemistry, or at all interested in its progress. They
were all so intent upon accomplishing their own objects, or those of
their sovereign, that they had neither time nor inclination to think
of science, and certainly no money to devote to any of its votaries.
What minister in Great Britain ever attempted to cherish the sciences,
or to reward those who cultivate them with success? If we except Mr.
Montague, who procured the place of master of the Mint for Sir Isaac
Newton, I know of no one. While in every other nation in Europe science
is directly promoted, and considerable sums are appropriated for its
cultivation, and for the support of a certain number of individuals
who have shown themselves capable of extending its boundaries, not a
single farthing has been devoted to any such purpose in Great Britain.
Science has been left entirely to itself; and whatever has been done
by way of promoting it has been performed by the unaided exertions of
private individuals. George III. himself was a patron of literature
and an encourager of _botany_. He might have been disposed to reward
the unrivalled eminence which Scheele had attained; but this he could
only have done by bestowing on him a pension out of his privy purse.
No situation which Scheele could fill was at his disposal. The
universities and the church were both shut against a Lutheran; and no
pharmaceutical places exist in this country to which Scheele could have
been appointed. If any such project ever existed, it must have been an
idea which struck some man of science that such a proposal to a man
of Scheele's eminence would redound to the credit of the country. But
that such a project should have been broached by a British ministry, or
by any man of great political influence, is an opinion that no person
would adopt who has paid any attention to the history of Great Britain
since the Revolution to the present time.

Scheele fell at last a sacrifice to his ardent love for his science. He
was unable to abstain from experimenting, and many of his experiments
were unavoidably made in his shop, where he was exposed during winter,
in the ungenial climate of Sweden, to cold draughts of air. He caught
rheumatism in consequence, and the disease was aggravated by his ardour
and perseverance in his pursuits. When he purchased the apothecary's
shop in which his business was carried on, he had formed the resolution
of marrying the widow of his predecessor, and he had only delayed
it from the honourable principle of acquiring, in the first place,
sufficient property to render such an alliance desirable on her part.
At length, in the month of March, 1786, he declared his intention of
marrying her; but his disease at this time increased very fast, and
his hopes of recovery daily diminished. He was sensible of this; but
nevertheless he performed his promise, and married her on the 19th of
May, at a time when he lay on his deathbed. On the 21st, he left her by
his will the disposal of the whole of his property; and, the same day
on which he so tenderly provided for her, he died.

I shall now endeavour to give the reader an idea of the principal
chemical discoveries for which we are indebted to Scheele: his papers,
with the exception of his book on _air and fire_, which was published
separately by Bergman, are all to be found either in the Memoirs of
the Stockholm Academy of Science, or in Crell's Journal; they were
collected, and a Latin translation of them, made by Godfrey Henry
Schaefer, published at Leipsic, in 1788, by Henstreit, the editor of
the three last volumes of Bergman's Opuscula. A French translation of
them was made in consequence of the exertions of M. Morveau; and an
English translation of them, in 1786, by means of Dr. Beddoes, when he
was a student in Edinburgh. There are also several German translations,
but I have never had an opportunity of seeing them.

1. Scheele's first paper was published by Retzius, in 1770; it gives a
method of obtaining pure tartaric acid: the process was to decompose
cream of tartar by means of chalk. One half of the tartaric acid unites
to the lime, and falls down in the state of a white insoluble powder,
being _tartrate of lime_. The cream of tartar, thus deprived of half
its acid, is converted into the neutral salt formerly distinguished
by the name of _soluble tartar_, from its great solubility in water:
it dissolves, and may be obtained in crystals, by the usual method of
crystallizing salts. The tartrate of lime is washed with water, and
then mixed with a quantity of dilute sulphuric acid, just capable of
saturating the lime contained in the tartrate of lime; the mixture
is digested for some time; the sulphuric acid displaces the tartaric
acid, and combines with the lime; and, as the sulphate of lime is but
very little soluble in water, the greatest part of it precipitates,
and the clear liquor is drawn off: it consists of tartaric acid,
held in solution by water, but not quite free from sulphate of lime.
By repeated concentrations, all the sulphate of lime falls down,
and at last the tartaric acid itself is obtained in large crystals.
This process is still followed by the manufacturers of this country;
for tartaric acid is used to a very considerable extent by the
calico-printers, in various processes; for example, it is applied,
thickened with gum, to different parts of cloth dyed Turkey red; the
cloth is then passed through water containing the requisite quantity of
chloride of lime: the tartaric acid, uniting with the lime, sets the
chlorine at liberty, which immediately destroys the red colour wherever
the tartaric acid has been applied, but leaves all the other parts of
the cloth unchanged.

2. The paper on _fluoric acid_ appeared in the Memoirs of the Stockholm
Academy, for 1771, when Scheele was in Scharenberg's apothecary's
shop in Stockholm, where, doubtless, the experiments were made. Three
years before, Margraaf had attempted an analysis of fluor spar, but
had discovered nothing. Scheele demonstrated that it is a compound of
lime and a peculiar acid, to which he gave the name of _fluoric_ acid.
This acid he obtained in solution in water; it was separated from
the fluor spar by sulphuric, muriatic, nitric, and phosphoric acids.
When the fluoric acid came in contact with water, a white crust was
formed, which proved, on examination, to be silica. Scheele at first
thought that this silica was a compound of fluoric acid and water; but
it was afterwards proved by Weigleb and by Meyer, that this notion is
inaccurate, and that the silica was corroded from the retort into which
the fluor spar and sulphuric acid were put. Bergman, who had adopted
Scheele's theory of the nature of silica, was so satisfied by these
experiments, that he gave it up, as Scheele himself did soon after.

Scheele did not obtain fluoric acid in a state of purity, put only
_fluosilicic acid_; nor were chemists acquainted with the properties
of fluoric acid till Gay-Lussac and Thenard published their Recherches
Physico-chimiques, in 1811.

3. Scheele's experiments on _manganese_ were undertaken at the request
of Bergman, and occupied him three years; they were published in the
Memoirs of the Stockholm Academy, for 1774, and constitute the most
memorable and important of all his essays, since they contain the
discovery of two new bodies, which have since acted so conspicuous a
part, both in promoting the progress of the science, and in improving
the manufactures of Europe. These two substances are _chlorine_ and
_barytes_, the first account of both of which occur in this paper.

The ore of manganese employed in these experiments was the _black
oxide_, or _deutoxide_, of manganese, as it is now called. Scheele's
method of proceeding was to try the effect of all the different
reagents on it. It dissolved in sulphurous and nitrous acids, and the
solution was colourless. Dilute sulphuric acid did not act upon it,
nor nitric acid; but concentrated sulphuric acid dissolved it by the
assistance of heat. The solution of sulphate of manganese in water was
colourless and crystallized in very oblique rhomboidal prisms, having
a bitter taste. Muriatic acid effervesced with it, when assisted by
heat, and the elastic fluid that passed off had a yellowish colour, and
the smell of aqua regia. He collected quantities of this elastic fluid
(_chlorine_) in bladders, and determined some of its most remarkable
properties: it destroyed colours, and tinged the bladder yellow,
as nitric acid does. This elastic fluid, in Scheele's opinion, was
muriatic acid deprived of phlogiston. By phlogiston Scheele meant, in
this place, hydrogen gas. He considered muriatic acid as a compound
of chlorine and hydrogen. Now this is the very theory that was
established by Davy in consequence of his own experiments and those of
Gay-Lussac and Thenard. Scheele's mode of collecting chlorine gas in a
bladder, did not enable him to determine its characters with so much
precision as was afterwards done. But his accuracy was so great, that
every thing which he stated respecting it was correct so far as it went.

Most of the specimens of manganese ore which Scheele examined,
contained more or less barytes, as has since been determined, in
combination with the oxide. He separated this barytes, and determined
its peculiar properties. It dissolved in nitric and muriatic acids,
and formed salts capable of crystallizing, and permanent in the air.
Neither potash, soda, nor lime, nor any _base_ whatever, was capable of
precipitating it from these acids. But the alkaline carbonates threw it
down in the state of a white powder, which dissolved with effervescence
in acids. Sulphuric acid and all the sulphates threw it down in the
state of a white powder, which was insoluble in water and in acids.
This sulphate cannot be decomposed by any acid or base whatever. The
only practicable mode of proceeding is to convert the sulphuric acid
into sulphur, by heating the salt with charcoal powder, along with a
sufficient quantity of potash, to bring the whole into fusion. The
fused mass, edulcorated, is soluble in nitric or muriatic acid, and
thus may be freed from charcoal, and the barytes obtained in a state
of purity. Scheele detected barytes, also, in the potash made from
trees or other smaller vegetables; but at that time he was unacquainted
with _sulphate of barytes_, which is so common in various parts of the
earth, especially in lead-mines.

To point out all the new facts contained in this admirable essay,
it would be necessary to transcribe the whole of it. He shows the
remarkable analogy between manganese and metallic oxides. Bergman, in
an appendix affixed to Scheele's paper, states his reasons for being
satisfied that it is really a metallic oxide. Some years afterwards,
Assessor Gahn succeeded in reducing it to the metallic state, and thus
dissipating all remaining doubts on the subject.

4. In 1775 he gave a new method of obtaining benzoic acid from benzoin.
His method was, to digest the benzoin with pounded chalk and water,
till the whole of the acid had combined with lime, and dissolved in the
water. It is requisite to take care to prevent the benzoin from running
into clots. The liquid thus containing benzoate of lime in solution is
filtered, and muriatic acid added in sufficient quantity to saturate
the lime. The benzoic acid is separated in white flocks, which may be
easily collected and washed. This method, though sufficiently easy, is
not followed by practical chemists, at least in this country. The acid
when procured by precipitation is not so beautiful as what is procured
by sublimation; nor is the process so cheap or so rapid. For these
reasons, Scheele's process has not come into general use.

5. During the same year, 1775, his essay on arsenic and its acid was
also published in the Memoirs of the Stockholm Academy. In this essay
he shows various processes, by means of which white arsenic may be
converted into an acid, having a very sour taste, and very soluble in
water. This is the acid to which the name of _arsenic acid_ has been
since given. Scheele describes the properties of this acid, and the
salts which it forms, with the different bases. He examines, also, the
action of white arsenic upon different bodies, and throws light upon
the arsenical salt of Macquer.

6. The object of the little paper on silica, clay, and alum, published
in the Memoirs of the Stockholm Academy, for 1776, is to prove that
alumina and silica are two perfectly distinct bodies, possessed
of different properties. This he does with his usual felicity of
experiment. He shows, also, that alumina and lime are capable of
combining together.

7. The same year, and in the same volume of the Stockholm Memoirs, he
published his experiments on a urinary calculus. The calculus upon
which his experiments were made, happened to be composed of _uric
acid_. He determined the properties of this new acid, particularly
the characteristic one of dissolving in nitric acid, and leaving a
beautiful pink sediment when the solution is gently evaporated to
dryness.

8. In 1778 appeared his experiments on molybdena. What is now called
_molybdena_ is a soft foliated mineral, having the metallic lustre,
and composed of two atoms sulphur united to one atom of metallic
molybdenum. It was known before, from the experiments of Quest, that
this substance contains sulphur. Scheele extracted from it a white
powder, which he showed to possess acid properties, though it was
insoluble in water. He examined the characters of this acid, called
molybdic acid, and the nature of the salts which it is capable of
forming by uniting with bases.

9. In the year 1777 was published the Experiments of Scheele on Air
and Fire, with an introduction, by way of preface, from Bergman, who
seems to have superintended the publication. This work is undoubtedly
the most extraordinary production that Scheele has left us; and is
really wonderful, if we consider the circumstances under which it was
produced. Scheele ascertained that common air is a mixture of two
distinct elastic fluids, one of which alone is capable of supporting
combustion, and which, therefore, he calls _empyreal air_; the
other, being neither capable of maintaining combustion, nor of being
breathed, he called _foul air_. These are the _oxygen_ and _azote_
of modern chemists. Oxygen he showed to be heavier than common air;
bodies burnt in it with much greater splendour than in common air.
Azote he found lighter than common air; bodies would not burn in it at
all. He showed that metallic _calces_, or metallic _oxides_, as they
are now called, contain oxygen as a constituent, and that when they
are reduced to the metallic state, oxygen gas is disengaged. In his
experiments on fulminating gold he shows, that during the fulmination
a quantity of azotic gas is disengaged; and he deduces from a great
many curious facts, which are stated at length, that ammonia is a
compound of _azote_ and _hydrogen_. His apparatus was not nice enough
to enable him to determine the proportions of the various ingredients
of the bodies which he analyzed: accordingly that is seldom attempted;
and when it is, as was the case with common air, the results are very
unsatisfactory. He deduces from his experiments, that the volume of
oxygen gas, in common air, is between a third and a fourth: we now know
that it is exactly a fifth.

In this book, also, we have the first account of sulphuretted
hydrogen gas, and of its properties. He gives it the name of stinking
sulphureous air.

The observations and new views respecting heat and light in this
work are so numerous, that I am obliged to omit them: nor do I think
it necessary to advert to his theory, which, when his book was
published, was exceedingly plausible, and undoubtedly constituted
a great step towards the improvements which soon after followed.
His own experiments, had he attended a little more closely to the
_weights_, and the alterations of them, would have been sufficient
to have overturned the whole doctrine of phlogiston. Upon the whole
it may be said, with confidence, that there is no chemical book in
existence which contains a greater number of new and important facts
than this work of Scheele, at the time it was published. Yet most of
his discoveries were made, also, by others. Priestley and Lavoisier,
from the superiority of their situations, and their greater means of
making their labours speedily known to the public, deprived him of
much of that reputation to which, in common circumstances, he would
have been entitled. Priestley has been blamed for the rapidity of his
publications, and the crude manner in which he ushered his discoveries
to the world. But had he kept them by him till he had brought them to
a sufficient degree of maturity, it is obvious that he would have been
anticipated in the most important of them by Scheele.

10. In the Memoirs of the Stockholm Academy, for 1779, there is a
short but curious paper of Scheele, giving an account of some results
which he had obtained. If a plate of iron be moistened by a solution
of common salt, or of sulphate of soda, and left for some weeks in a
moist cellar, an efflorescence of carbonate of soda covers the surface
of the plate. The same decomposition of common salt and evolution of
soda takes place when unslacked quicklime is moistened with a solution
of common salt, and left in a similar situation. These experiments led
afterwards to various methods of decomposing common salt, and obtaining
from it carbonate of soda. The phenomena themselves are still wrapped
up in considerable obscurity. Berthollet attempted an explanation
afterwards in his Chemical Statics; but founded on principles not
easily admissible.

11. During the same year, his experiments on _plumbago_ were published.
This substance had been long employed for making black-lead pencils;
but nothing was known concerning its nature. Scheele, with his usual
perseverance, tried the effect of all the different reagents, and
showed that it consisted chiefly of _carbon_, but was mixed with a
certain quantity of iron. It was concluded from these experiments,
that plumbago is a carburet of iron. But the quantity of iron differs
so enormously in different specimens, that this opinion cannot be
admitted. Sometimes the iron amounts only to one-half per cent., and
sometimes to thirty per cent. Plumbago, then, is carbon mixed with a
variable proportion of iron, or carburet of iron.

12. In 1780 Scheele published his experiments on milk, and showed that
sour milk contains a peculiar acid, to which the name of _lactic_ acid
has been given.

He found that when sugar of milk is dissolved in nitric acid, and the
solution allowed to cool, small crystalline grains were deposited.
These grains have an acid taste, and combine with bases: they have
peculiar properties, and therefore constitute a particular acid, to
which the name of _saclactic_ was given. It is formed, also, when
gum is dissolved in nitric acid; on this account it has been called,
_mucic_ acid.

13. In 1781 his experiments on a heavy mineral called by the Swedes
_tungsten_, were published. This substance had been much noticed on
account of its great weight; but nothing was known respecting its
nature. Scheele, with his usual skill and perseverance, succeeded in
proving that it was a compound of lime and a peculiar acid, to which
the name of _tungstic acid_ was given. Tungsten was, therefore, a
tungstate of lime. Bergman, from its great weight, suspected that
tungstic acid was in reality the oxide of a metal, and this conjecture
was afterwards confirmed by the Elhuyarts, who extracted the same acid
from wolfram, and succeeded in reducing it to the metallic state.

14. In 1782 and 1783 appeared his experiments on _Prussian blue_, in
order to discover the nature of the colouring matter. These experiments
were exceedingly numerous, and display uncommon ingenuity and sagacity.
He succeeded in demonstrating that _prussic acid_, the name at that
time given to the colouring principle, was a compound of _carbon_ and
_azote_. He pointed out a process for obtaining prussic acid in a
separate state, and determined its properties. This paper threw at once
a ray of light on one of the obscurest parts of chemistry. If he did
not succeed in elucidating this difficult department completely, the
fault must not be ascribed to him, but to the state of chemistry when
his experiments were made; in fact, it would have been impossible to
have gone further, till the nature of the different elastic fluids at
that time under investigation had been thoroughly established. Perhaps
in 1783 there was scarcely any other individual who could have carried
this very difficult investigation so far as it was carried by Scheele.

15. In 1783 appeared his observations on the _sweet principle of oils_.
He observed, that when olive oil and litharge are combined together,
a sweet substance separates from the oil and floats on the surface.
This substance, when treated with nitric acid, yields _oxalic acid_. It
was therefore closely connected with sugar in its nature. He obtained
the same sweet matter from linseed oil, oil of almonds, of rape-seed,
from hogs' lard, and from butter. He therefore concluded that it was a
principle contained in all the expressed or fixed oils.

16. In 1784 he pointed out a method by which _citric acid_ may be
obtained in a state of purity from lemon-juice. He likewise determined
its characters, and showed that it was entitled to rank as a peculiar
acid.

It was during the same year that he observed a white earthy matter,
which may be obtained by washing rhubarb, in fine powder, with a
sufficient quantity of water. This earthy matter he decomposed, and
ascertained that it was a neutral salt, composed of oxalic acid,
combined with lime. In a subsequent paper he showed, that the same
oxalate of lime exists in a great number of roots of various plants.

17. In 1786 he showed that apples contain a peculiar acid, the
properties of which he determined, and to which the name of _malic
acid_ has been given. In the same paper he examined all the common acid
fruits of this country--gooseberries, currants, cherries, bilberries,
&c., and determined the peculiar acids which they contain. Some owe
their acidity to malic acid, some to citric acid, and some to tartaric
acid; and not a few hold two, or even three, of these acids at the same
time.

The same year he showed that the syderum of Bergman was phosphuret of
iron, and the _acidum perlatum_ of Proust _biphosphate of soda_.

The only other publication of Scheele, during 1785, was a short
notice respecting a new mode of preparing _magnesia alba_. If
sulphate of magnesia and common salt, both in solution, be mixed in
the requisite proportions, a double decomposition takes place, and
there will be formed sulphate of soda and muriate of magnesia. The
greatest part of the former salt may be obtained out of the mixed ley
by crystallization, and then the magnesia alba may be thrown down,
from the muriate of magnesia, by means of an alkaline carbonate. The
advantage of this new process is, the procuring of a considerable
quantity of sulphate of soda in exchange for common salt, which is a
much cheaper substance.

18. The last paper which Scheele published appeared in the Memoirs
of the Stockholm Academy, for 1786: in it he gave an account of the
characters of gallic acid, and the method of obtaining that acid from
nutgalls.

Such is an imperfect sketch of the principal discoveries of Scheele.
I have left out of view his controversial papers, which have now lost
their interest; and a few others of minor importance, that this notice
might not be extended beyond its due length. It will be seen that
Scheele extended greatly the number of acids; indeed, he more than
doubled the number of these bodies known when he began his chemical
labours. The following acids were discovered by him; or, at least, it
was he that first accurately pointed out their characters:

  Fluoric acid
  Molybdic acid
  Tungstic acid
  Arsenic acid
  Lactic acid
  Gallic acid
  Tartaric acid
  Oxalic acid
  Citric acid
  Malic acid
  Saclactic
  Chlorine.

To him, also, we owe the first knowledge of barytes, and of the
characters of manganese. He determined the nature of the constituents
of ammonia and prussic acid: he first determined the compound nature of
common air, and the properties of the two elastic fluids of which it is
composed. What other chemist, either a contemporary or predecessor of
Scheele, can be brought in competition with him as a discoverer? And
all was performed under the most unpropitious circumstances, and during
the continuance of a very short life, for he died in the 44th year of
his age.




CHAPTER III.

PROGRESS OF SCIENTIFIC CHEMISTRY IN FRANCE.


I have already given an account of the state of chemistry in France,
during the earlier part of the eighteenth century, as it was cultivated
by the Stahlian school. But the new aspect which chemistry put on in
Britain in consequence of the discoveries of Black, Cavendish, and
Priestley, and the conspicuous part which the gases newly made known
was likely to take in the future progress of the science, drew to
the study of chemistry, sometime after the middle of the eighteenth
century, a man who was destined to produce a complete revolution, and
to introduce the same precision, and the same accuracy of deductive
reasoning which distinguishes the other branches of natural science.
This man was Lavoisier.

Antoine Laurent Lavoisier was born in Paris on the 26th of August,
1743. His father being a man of opulence spared no expense on his
education. His taste for the physical sciences was early displayed, and
the progress which he made in them was uncommonly rapid. In the year
1764 a prize was offered by the French government for the best and most
economical method of lighting the streets of an extensive city. Young
Lavoisier, though at that time only twenty-one years of age, drew up a
memoir on the subject which obtained the gold medal. This essay was
inserted in the Memoirs of the French Academy of Sciences, for 1768. It
was during that year, when he was only twenty-five years of age that
he became a member of that scientific body. By this time he was become
fully conscious of his own strength; but he hesitated for some time to
which of the sciences he should devote his attention. He tried pretty
early to determine, experimentally, some chemical questions which at
that time drew the attention of practical chemists. For example: an
elaborate paper of his appeared in the Memoirs of the French Academy,
for 1768, on the composition of _gypsum_--a point at that time not
settled; but which Lavoisier proved, as Margraaf had done before him,
to be a compound of sulphuric acid and lime. In the Memoirs of the
Academy, for 1770, two papers of his appeared, the object of which
was to determine whether water could, as Margraaf had pretended, be
converted into _silica_ by long-continued digestion in glass vessels.
Lavoisier found, as Margraaf stated, that when water is digested for a
long time in a glass retort, a little silica makes its appearance; but
he showed that this silica was wholly derived from the retort. Glass,
it is well known, is a compound of silica and a fixed alkali. When
water is long digested on it the glass is slightly corroded, a little
alkali is dissolved in the water and a little silica separated in the
form of a powder.

He turned a good deal of his attention also to geology, and made
repeated journeys with Guettard into almost every part of France.
The object in view was an accurate description of the mineralogical
structure of France--an object accomplished to a considerable extent by
the indefatigable exertions of Guettard, who published different papers
on the subject in the Memoirs of the French Academy, accompanied with
geological maps; which were at that time rare.

The mathematical sciences also engrossed a considerable share of his
attention. In short he displayed no great predilection for one study
more than another, but seemed to grasp at every branch of science with
equal avidity. While in this state of suspension he became acquainted
with the new and unexpected discoveries of Black, Cavendish, and
Priestley, respecting the gases. This opened a new creation to his
view, and finally determined him to devote himself to scientific
chemistry.

In the year 1774 he published a volume under the title of "Essays
Physical and Chemical." It was divided into two parts. The first part
contained an historical detail of every thing that had been done on
the subject of airs, from the time of Paracelsus down to the year
1774. We have the opinions and experiments of Van Helmont, Boyle,
Hales, Boerhaave, Stahl, Venel, Saluces, Black, Macbride, Cavendish,
and Priestley. We have the history of Meyer's acidum pingue, and the
controversy carried on in Germany, between Jacquin on the one hand, and
Crans and Smeth on the ether.

In the second part Lavoisier relates his own experiments upon gaseous
substances. In the first four chapters he shows the truth of Dr.
Black's theory of fixed air. In the 4th and 5th chapters he proves that
when metallic calces are reduced, by heating them with charcoal, an
elastic fluid is evolved, precisely of the same nature with carbonic
acid gas. In the 6th chapter he shows that when metals are calcined
their weight increases, and that a portion of air equal to their
increase in weight is absorbed from the surrounding atmosphere. He
observed that in a given bulk of air calcination goes on to a certain
point and then stops altogether, and that air in which metals have
been calcined does not support combustion so well as it did before any
such process was performed in it. He also burned phosphorus in a given
volume of air, observed the diminution of volume of the air and the
increase of the weight of the phosphorus.

Nothing in these essays indicates the smallest suspicion that air
was a mixture of two distinct fluids, and that only one of them was
concerned in combustion and calcination; although this had been already
deduced by Scheele from his own experiments, and though Priestley had
already discovered the existence and peculiar properties of oxygen
gas. It is obvious, however, that Lavoisier was on the way to make
these discoveries, and had neither Scheele nor Priestley been fortunate
enough to hit upon oxygen gas, it is exceedingly likely that he would
himself have been able to have made that discovery.

Dr. Priestley, however, happened to be in Paris towards the end of
1774, and exhibited to Lavoisier, in his own laboratory in Paris,
the method of procuring oxygen gas from red oxide of mercury. This
discovery altered all his views, and speedily suggested not only
the nature of atmospheric air, but also what happens during the
calcination of metals and the combustion of burning bodies in general.
These opinions when once formed he prosecuted with unwearied industry
for more than twelve years, and after a vast number of experiments,
conducted with a degree of precision hitherto unattempted in chemical
investigations, he boldly undertook to disprove the existence of
phlogiston altogether, and to explain all the phenomena hitherto
supposed to depend upon that principle by the simple combination or
separation of oxygen from bodies.

In these opinions he had for some years no coadjutors or followers,
till, in 1785, Berthollet at a meeting of the Academy of Sciences,
declared himself a convert. He was followed by M. Fourcroy, and soon
after Guyton de Morveau, who was at that time the editor of the
chemical department of the Encyclopédie Méthodique, was invited to
Paris by Lavoisier and prevailed upon to join the same party. This was
followed by a pretty vigorous controversy, in which Lavoisier and his
associates gained a signal victory.

Lavoisier, after Buffon and Tillet, was treasurer to the academy,
into the accounts of which he introduced both economy and order. He
was consulted by the National Convention on the most eligible means
of improving the manufacture of assignats, and of augmenting the
difficulty of forging them. He turned his attention also to political
economy, and between 1778 and 1785 he allotted 240 arpents in the
Vendomois to experimental agriculture, and increased the ordinary
produce by one-half. In 1791 the Constituent Assembly invited him
to draw up a plan for rendering more simple the collection of the
taxes, which produced an excellent report, printed under the title of
"Territorial Riches of France."

In 1776 he was employed by Turgot to inspect the manufactory of
gunpowder; which he made to carry 120 toises, instead of 90. It is
pretty generally known, that during the war of the American revolution,
the French gunpowder was much superior to the British; but it is
perhaps not so generally understood, that for this superiority the
French government were indebted to the abilities of Lavoisier. During
the war of the French revolution, the quality of the powder of the two
nations was reversed; the English being considerably superior to that
of the French, and capable of carrying further. This was put to the
test in a very remarkable way at Cadiz.

During the horrors of the dictatorship of Robespierre, Lavoisier began
to suspect that he would be stripped of his property, and informed
Lalande that he was extremely willing to work for his subsistence. It
was supposed that he meant to pursue the profession of an apothecary,
as most congenial to his studies: but he was accused, along with the
other _farmers-general_, of defrauding the revenue, and thrown into
prison. During that sanguinary period imprisonment and condemnation
were synonymous terms. Accordingly, on the 8th of May, 1794, he
suffered on the scaffold, with twenty-eight farmers-general, at the
early age of fifty-one. It has been, alleged that Fourcroy, who at that
time possessed considerable influence, might have saved him had he been
disposed to have exerted himself. But this accusation has never been
supported by any evidence. Lavoisier was a man of too much eminence
to be overlooked, and no accused person at that time could be saved
unless he was forgotten. A paper was presented to the tribunal, drawn
up by M. Hallé, giving a catalogue of the works, and a recapitulation
of the merits of Lavoisier; but it was thrown aside without even being
read, and M. Hallé had reason to congratulate himself that his useless
attempts to save Lavoisier did not terminate in his own destruction.

Lavoisier was tall, and possessed a countenance full of benignity,
through which his genius shone forth conspicuous. He was mild, humane,
sociable, obliging, and he displayed an incredible degree of activity.
His influence was great, on account of his fortune, his reputation,
and the place which he held in the treasury; but all the use which
he made of it was to do good. His wife, whom he married in 1771,
was Marie-Anna-Pierette-Paulze, daughter of a farmer-general, who
was put to death at the same time with her husband; she herself was
imprisoned, but saved by the fortunate destruction of the dictator
himself, together with his abettors. It would appear that she was able
to save a considerable part of her husband's fortune: she afterwards
married Count Rumford, whom she survived.

Besides his volume of Physical and Chemical Essays, and his Elements of
Chemistry, published in 1789, Lavoisier was the author of no fewer than
sixty memoirs, which were published in the volumes of the Academy of
Sciences, from 1772, to 1788, or in other periodical works of the time.
I shall take a short review of the most important of these memoirs,
dividing them into two parts: I. Those that are not connected with his
peculiar chemical theory; II. Those which were intended to disprove the
existence of phlogiston, and establish the antiphlogistic theory.

I. I have already mentioned his paper on gypsum, published in the
Memoirs of the Academy, for 1768. He proves, by very decisive
experiments, that this salt is a compound of sulphuric acid, lime,
and water. But this had been already done by Margraaf, in a paper
inserted into the Memoirs of the Berlin Academy, for 1750, entitled
"An Examination of the constituent parts of the Stones that become
luminous." The most remarkable circumstance attending this paper is,
that an interval of eighteen years should elapse without Lavoisier's
having any knowledge of this important paper of Margraaf; yet he quotes
Pott and Cronstedt, who had written on the same subject later than
Margraaf, at least Cronstedt. What makes this still more singular and
unaccountable is, that a French translation of Margraaf's Opuscula had
been published in Paris, in the year 1762. That a man in Lavoisier's
circumstances, who, as appears from his paper, had paid considerable
attention to chemistry, should not have perused the writings of one
of the most eminent chemists that had ever existed, when they were
completely within his power, constitutes, I think, one of the most
extraordinary phenomena in the history of science.

2. If a want of historical knowledge appears conspicuous in Lavoisier's
first chemical paper, the same remark cannot be applied to his second
paper, "On the Nature of Water, and the Experiments by which it has
been attempted to prove the possibility of changing it into Earth,"
which was inserted in the Memoirs of the French Academy, for 1770. This
memoir is divided into two parts. In the first he gives a history of
the progress of opinions on the subject, beginning with Van Helmont's
celebrated experiment on the willow; then relating those of Boyle,
Triewald, Miller, Eller, Gleditch, Bonnet, Kraft, Alston, Wallerius,
Hales, Duhamel, Stahl, Boerhaave, Geoffroy, Margraaf, and Le Roy. This
first part is interesting, in an historical point of view, and gives
a very complete account of the progress of opinions upon the subject
from the very first dawn of scientific chemistry down to his own time.
There is, it is true, a remarkable difference between the opinions
of his predecessors respecting the conversion of water into earth,
and the experiments of Margraaf on the composition of _selenite_. The
former were inaccurate, and were recorded by him that they might be
refuted; but the experiments of Margraaf were accurate, and of the
same nature with his own. The second part of this memoir contains his
own experiments, made with much precision, which went to show that
the earth was derived from the retort in which the experiments of
Margraaf were made, and that we have no proof whatever that water may
be converted into earth.

But these experiments of Lavoisier, though they completely disproved
the inferences that Margraaf drew from his observations, by no means
demonstrated that water might not be converted into different animal
and vegetable substances by the processes of digestion. Indeed there
can be no doubt that this is the case, and that the oxygen and hydrogen
of which it is composed, enter into the composition of by far the
greater number of animal and vegetable bodies produced by the action
of the functions of living animals and vegetables. We have no evidence
that the carbon, another great constituent of vegetable bodies,
and the carbon and azote which constitute so great a proportion of
animal substances, have their origin from water. They are probably
derived from the food of plants and animals, and from the atmosphere
which surrounds them, and which contains both of these principles in
abundance.

Whether the silica, lime, alumina, magnesia, and iron, that exist in
small quantity in plants, be derived from water and the atmosphere, is
a question which we are still unable to answer. But the experiments
of Schrader, which gained the prize offered by the Berlin Academy,
in the year 1800, for the best essay on the following subject: _To
determine the earthy constituents of the different kinds of corn, and
to ascertain whether these earthy parts are formed by the processes of
vegetation_, show at least that we cannot account for their production
in any other way. Schrader analyzed the seeds of wheat, rye, barley,
and oats, and ascertained the quantity of earthy matter which each
contained. He then planted these different seeds in flowers of sulphur,
and in oxides of antimony and zinc, watering them regularly with
distilled water. They vegetated very well. He then dried the plants,
and analyzed what had been the produce of a given weight of seed, and
he found that the earthy matter in each was greater than it had been in
the seeds from which they sprung. Now as the sulphur and oxides of zinc
and antimony could furnish no earthy matter, no other source remains
but the water with which the plants were fed, and the atmosphere
with which they were surrounded. It may be said, indeed, that earthy
matter is always floating about in the atmosphere, and that in this
way they may have obtained all the addition of these principles which
they contained. This is an objection not easily obviated, and yet it
would require to be obviated before the question can be considered as
answered.

3. Lavoisier's next paper, inserted in the Memoirs of the Academy, for
1771, was entitled "Calculations and Observations on the Project of
the establishment of a Steam-engine to supply Paris with Water." This
memoir, though long and valuable, not being strictly speaking chemical,
I shall pass over. Mr. Watt's improvements seem to have been unknown
to Lavoisier, indeed as his patent was only taken out in 1769, and as
several years elapsed before the merits of his new steam-engine became
generally known, Lavoisier's acquaintance with it in 1771 could hardly
be expected.

4. In 1772 we find a paper, by Lavoisier, in the Memoirs of the
Academy, "On the Use of Spirit of Wine in the analysis of Mineral
Waters." He shows how the earthy muriates may be separated from the
sulphates by digesting the mixed mass in alcohol. This process no doubt
facilitates the separation of the salts from each other: but it is
doubtful whether the method does not occasion new inaccuracies that
more than compensate the facility of such separations. When different
salts are dissolved in water in small quantities, it may very well
happen that they do not decompose each other, being at too great a
distance from each other to come within the sphere of mutual action.
Thus it is possible that sulphate of soda and muriate of lime may exist
together in the same water. But if we concentrate this water very
much, and still more, if we evaporate to dryness, the two salts will
gradually come into the sphere of mutual action, a double decomposition
will take place, and there will be formed sulphate of lime and common
salt. If upon the dry residue we pour as much distilled water as was
driven off by the evaporation, we shall not be able to dissolve the
saline matter deposited; a portion of sulphate of lime will remain
in the state of a powder. Yet before the evaporation, all the saline
contents of the water were in solution, and they continued in solution
till the water was very much concentrated. This is sufficient to show
that the nature of the salts was altered by the evaporation. If we
digest the dry residue in spirit of wine, we may dissolve a portion of
muriate of lime, if the quantity of that salt in the original water was
greater than the sulphate of soda was capable of decomposing: but if
the quantity was just what the sulphate of soda could decompose, the
alcohol will dissolve nothing, if it be strong enough, or nothing but a
little common salt, if its specific gravity was above 0·820. We cannot,
therefore, depend upon the salts which we obtain after evaporating a
mineral water to dryness, being the same as those which existed in the
mineral water itself. The nature of the salts must always be determined
some other way.

5. In the Memoirs of the Academy, for 1772 (published in 1776), are
inserted two elaborate papers of Lavoisier, on the combustion of the
diamond. The combustibility of the diamond was suspected by Newton,
from its great refractive power. His suspicion was confirmed in
1694, by Cosmo III., Grand Duke of Tuscany, who employed Averani and
Targioni to try the effect of powerful burning-glasses upon diamonds.
They were completely dissipated by the heat. Many years after, the
Emperor Francis I. caused various diamonds to be exposed to the heat
of furnaces. They also were dissipated, without leaving any trace
behind them. M. Darcet, professor of chemistry at the Royal College
of Paris, being employed with Count Lauragais in a set of experiments
on the manufacture of porcelain, took the opportunity of trying what
effect the intense heat of the porcelain furnaces produced upon
various bodies. Diamonds were not forgotten. He found that they were
completely dissipated by the heat of the furnace, without leaving any
traces behind them. Darcet found that a violent heat was not necessary
to volatilize diamonds. The heat of an ordinary furnace was quite
sufficient. In 1771 a diamond, belonging to M. Godefroi Villetaneuse,
was exposed to a strong heat by Macquer. It was placed upon a cupel,
and raised to a temperature high enough to melt copper. It was observed
to be surrounded with a low red flame, and to be more intensely red
than the cupel. In short, it exhibited unequivocal marks of undergoing
real combustion.

These experiments were soon after repeated by Lavoisier before a
large company of men of rank and science. The real combustion of the
diamond was established beyond doubt; and it was ascertained also,
that if it be completely excluded from the air, it may be exposed to
any temperature that can be raised in a furnace without undergoing
any alteration. Hence it is clear that the diamond is not a volatile
substance, and that it is dissipated by heat, not by being volatilized,
but by being burnt.

The object of Lavoisier in his experiments was to determine the nature
of the substance into which the diamond was converted by burning. In
the first part he gives as usual a history of every thing which had
been done previous to his own experiments on the combustion of the
diamond. In the second part we have the result of his own experiments
upon the same subject. He placed diamonds on porcelain supports in
glass jars standing inverted over water and over mercury; and filled
with common air and with oxygen gas.[4]

 [4] The reader will bear in mind that though the memoir was inserted
 in the Mem. de l'Acad., for 1772, it was in fact published in 1776,
 and the experiments were made in 1775 and 1776.

The diamonds were consumed by means of burning-glasses. No _water_ or
_smoke_ or _soot_ made their appearance, and no alteration took place
on the bulk of the air when the experiments were made over mercury.
When they were made over water, the bulk of the air was somewhat
diminished. It was obvious from this that diamond when burnt in air or
oxygen gas, is converted into a gaseous substance, which is absorbed by
water. On exposing air in which diamond had been burnt, to lime-water,
a portion of it was absorbed, and the lime-water was rendered milky.
From this it became evident, that when diamond is burnt, _carbonic
acid_ is formed, and this was the only product of the combustion that
could be discovered.

Lavoisier made similar experiments with charcoal, burning it in air and
oxygen gas, by means of a burning-glass. The results were the same:
carbonic acid gas was formed in abundance, and nothing else. These
experiments might have been employed to support and confirm Lavoisier's
peculiar theory, and they were employed by him for that purpose
afterwards. But when they were originally published, no such intention
appeared evident; though doubtless he entertained it.

6. In the second volume of the Journal de Physique, for 1772, there
is a short paper by Lavoisier on the conversion of water into ice. M.
Desmarets had given the academy an account of Dr. Black's experiments,
to determine the latent heat of water. This induced Lavoisier to relate
his experiments on the same subject. He does not inform us whether
they were made in consequence of his having become acquainted with Dr.
Black's theory, though there can be no doubt that this must have been
the case. The experiments related in this short paper are not of much
consequence. But I have thought it worth while to notice it because it
authenticates a date at which Lavoisier was acquainted with Dr. Black's
theory of latent heat.

7. In the third volume of the Journal de Physique, there is an account
of a set of experiments made by Bourdelin, Malouin, Macquer, Cadet,
Lavoisier, and Baumé on the _white-lead ore_ of Pullowen. The report
is drawn up by Baumé. The nature of the ore is not made out by these
experiments. They were mostly made in the dry way, and were chiefly
intended to show that the ore was not a chloride of lead. It was most
likely a phosphate of lead.

8. In the Memoirs of the Academy, for 1774, we have the experiments of
Trudaine, de Montigny, Macquer, Cadet, Lavoisier, and Brisson, with
the great burning-glass of M. Trudaine. The results obtained cannot be
easily abridged, and are not of sufficient importance to be given in
detail.

9. Analysis of some waters brought from Italy by M. Cassini, junior.
This short paper appeared in the Memoirs of the Academy, for 1777. The
waters in question were brought from alum-pits, and were found to
contain alum and sulphate of iron.

10. In the same volume of the Memoirs of the Academy, appeared his
paper "On the Ash employed by the Saltpetre-makers of Paris, and on its
use in the Manufacture of Saltpetre." This is a curious and valuable
paper; but not sufficiently important to induce me to give an abstract
of it here.

11. In the Memoirs of the Academy, for 1777, appeared an elaborate
paper, by Lavoisier, "On the Combination of the matter of Fire, with
Evaporable Fluids, and the Formation of Elastic aeriform Fluids." In
this paper he adopts precisely the same theory as Dr. Black had long
before established. It is remarkable that the name of Dr. Black never
occurs in the whole paper, though we have seen that Lavoisier had
become acquainted with the doctrine of latent heat, at least as early
as the year 1772, as he mentioned the circumstance in a short paper
inserted that year in the Journal de Physique, and previously read to
the academy.

12. In the same volume of the Memoirs of the Academy, we have a paper
entitled "Experiments made by Order of the Academy, on the Cold
of the year 1775, by Messrs. Bezout, Lavoisier, and Vandermond."
It is sufficiently known that the beginning of the year 1776 was
distinguished in most parts of Europe by the weather. The object
of this paper, however, is rather to determine the accuracy of the
different thermometers at that time used in France, than to record the
lowest temperature which had been observed. It has some resemblance to
a paper drawn up about the same time by Mr. Cavendish, and published in
the Philosophical Transactions.

13. In the Memoirs of the Academy, for 1778, appeared a paper entitled
"Analysis of the Waters of the Lake Asphaltes, by Messrs. Macquer,
Lavoisier, and Sage." This water is known to be saturated with _salt_.
It is needless to state the result of the analysis contained in this
paper, because it is quite inaccurate. Chemical analysis had not at
that time made sufficient progress to enable chemists to analyze
mineral waters with precision.

The observation of Lavoisier and Guettard, which appeared at the
same time, on a species of steatite, which is converted by the fire
into a fine biscuit of porcelain, and on two coal-mines, the one in
Franche-Comté, the other in Alsace, do not require to be particularly
noticed.

14. In the Mem. de l'Académie, for 1780 (published in 1784), we have
a paper, by Lavoisier, "On certain Fluids which may be obtained in
an aeriform State, at a degree of Heat not much higher than the mean
Temperature of the Earth." These fluids are sulphuric ether, alcohol,
and water. He points out the boiling temperature of these liquids, and
shows that at that temperature the vapour of these bodies possesses
the elasticity of common air, and is permanent as long as the high
temperature continues. He burnt a mixture of vapour of ether and oxygen
gas, and showed that during the combustion carbonic acid gas is formed.
Lavoisier's notions respecting these vapours, and what hindered the
liquids at the boiling temperature from being all converted into vapour
were not quite correct. Our opinions respecting steam and vapours in
general were first rectified by Mr. Dalton.

15. In the Mem. de l'Académie, for 1780, appeared also the celebrated
paper on _heat_, by Lavoisier and Laplace. The object of this paper was
to determine the specific heat of various bodies, and to investigate
the proposals that had been made by Dr. Irvine for determining the
point at which a thermometer would stand, if plunged into a body
destitute of heat. This point is usually called the real zero.
They begin by describing an instrument which they had contrived to
measure the quantity of heat which leaves a body while it is cooling
a certain number of degrees. To this instrument they gave the name of
_calorimeter_. It consisted of a kind of hollow, surrounded on every
side by ice. The hot body was put into the centre. The heat which it
gave out while cooling was all expended in melting the ice, which was
of the temperature of 32°, and the quantity of heat was proportional
to the quantity of ice melted. Hence the quantity of ice melted, while
equal weights of hot bodies were cooling a certain number of degrees,
gave the direct ratios of the specific heats of each. In this way they
obtained the following specific heats:

                                     Specific heat.

  Water                                1
  Sheet-iron                           0·109985
  Glass without lead (crystal)         0·1929
  Mercury                              0·029
  Quicklime                            0·21689
  Mixture of 9 water with 16 lime      0·439116
  Sulphuric acid of 1·87058            0·334597
  4 sulphuric acid, 3 water            0·603162
  4 sulphuric acid, 5 water            0·663102
  Nitric acid of 1·29895               0·661391
  9⅓ nitric acid, 1 lime               0·61895
  1 saltpetre, 8 water                 0·8167

Their experiments were inconsistent with the conclusions drawn by Dr.
Irvine, respecting the real zero, from the diminution of the specific
heat, and the heat evolved when sulphuric acid was mixed with various
proportions of water, &c. If the experiments of Lavoisier and Laplace
approached nearly to accuracy, or, indeed, unless they were quite
inaccurate, it is obvious that the conclusions of Irvine must be quite
erroneous. It is remarkable that though the experiments of Crawford,
and likewise those of Wilcke, and of several others, on specific heat
had been published before this paper made its appearance, no allusion
whatever is made to these publications. Were we to trust to the
information communicated in the paper, the doctrine of specific heat
originated with Lavoisier and Laplace. It is true that in the fourth
part of the paper, which treats of combustion and respiration, Dr.
Crawford's, theory of animal heat is mentioned, showing clearly that
our authors were acquainted with his book on the subject. And, as this
theory is founded on the different specific heats of bodies, there
could be no doubt that he was acquainted with that doctrine.

16. In the Mem. de l'Académie, for 1780, occur the two following
memoirs:

Report made to the Royal Academy of Sciences on the Prisons. By Messrs.
Duhamel, De Montigny, Le Roy, Tenon, Tillet, and Lavoisier.

Report on the Process for separating Gold and Silver. By Messrs.
Macquer, Cadet, Lavoisier, Baumé, Cornette, and Berthollet.

17. In the Mem. de l'Académie, for 1781, we find a memoir by Lavoisier
and Laplace, on the electricity evolved when bodies are evaporated or
sublimed. The result of these experiments was, that when water was
evaporated electricity was always evolved. They concluded from these
observations, that whenever a body changes its state electricity
is always evolved. But when Saussure attempted to repeat these
observations, he could not succeed. And, from the recent experiments
of Pouillet, it seems to follow that electricity is evolved only when
bodies undergo chemical decomposition or combination. Such experiments
depend so much upon very minute circumstances, which are apt to escape
the attention of the observer, that implicit confidence cannot be
put in them till they have been often repeated, and varied in every
possible manner.

18. In the Memoires de l'Académie, for 1781, there is a paper by
Lavoisier on the comparative value of the different substances
employed as articles of fuel. The substances compared to each other
are pit-coal, coke, charcoal, and wood. It would serve no purpose to
state the comparison here, as it would not apply to this country; nor,
indeed, would it at present apply even to France.

We have, in the same volume, his paper on the mode of illuminating
theatres.

19. In the Memoires de l'Académie, for 1782 (printed in 1785), we
have a paper by Lavoisier on a method of augmenting considerably the
action of fire and of heat. The method which he proposes is a jet of
oxygen gas, striking against red-hot charcoal. He gives the result
of some trials made in this way. Platinum readily melted. Pieces of
ruby or sapphire were softened sufficiently to run together into one
stone. Hyacinth lost its colour, and was also softened. Topaz lost its
colour, and melted into an opaque enamel. Emeralds and garnets lost
their colour, and melted into opaque coloured glasses. Gold and silver
were volatilized; all the other metals, and even the metallic oxides,
were found to burn. Barytes also burns when exposed to this violent
heat. This led Lavoisier to conclude, as Bergman had done before him,
that Barytes is a metallic oxide. This opinion has been fully verified
by modern chemists. Both silica and alumina were melted. But he could
not fuse lime nor magnesia. We are now in possession of a still more
powerful source of heat in the oxygen and hydrogen blowpipe, which is
capable of fusing both lime and magnesia, and, indeed, every substance
which can be raised to the requisite heat without burning or being
volatilized. This subject was prosecuted still further by Lavoisier
in another paper inserted in a subsequent volume of the Memoires de
l'Académie. He describes the effect on rock-crystal, quartz, sandstone,
sand, phosphorescent quartz, milk quartz, agate, chalcedony, cornelian,
flint, prase, nephrite, jasper, felspar, &c.

20. In the same volume is inserted a memoir "On the Nature of the
aeriform elastic Fluids which are disengaged from certain animal
Substances in a state of Fermentation." He found that a quantity of
recent human fæces, amounting to about five cubic inches, when kept
at a temperature approaching to 60° emitted, every day for a month,
about half a cubic inch of gas. This gas was a mixture of eleven parts
carbonic acid gas, and one part of an inflammable gas, which burnt
with a blue flame, and was therefore probably carbonic oxide. Five
cubic inches of old human fæces from a necessary kept in the same
temperature, during the first fifteen days emitted about a third of
a cubic inch of gas each day; and during each of the second fifteen
days, about one fourth of a cubic inch. This gas was a mixture of
thirty-eight volumes of carbonic acid gas, and sixty-two volumes of a
combustible gas, burning with a blue flame, and probably carbonic oxide.

Fresh fæces do not effervesce with dilute sulphuric acid, but old moist
fæces do, and emit about eight times their volume of carbonic acid
gas. Quicklime, or caustic potash, mixed with fæces, puts a stop to
the evolution of gas, doubtless by preventing all fermentation. During
effervescence of fæcal matter the air surrounding it is deprived of a
little of its oxygen, probably in consequence of its combining with the
nascent inflammable gas which is slowly disengaged.

II. We come now to the new theory of combustion of which Lavoisier
was the author, and upon which his reputation with posterity will
ultimately depend. Upon this subject, or at least upon matters more
or less intimately connected with it, no fewer than twenty-seven
memoirs of his, many of them of a very elaborate nature, and detailing
expensive and difficult experiments, appeared in the different
volumes of the academy between 1774 and 1788. The analogy between the
combustion of bodies and the calcination of metals had been already
observed by chemists, and all admitted that both processes were
owing to the same cause; namely, the emission of _phlogiston_ by the
burning or calcining body. The opinion adopted by Lavoisier was, that
during burning and calcination nothing whatever left the bodies, but
that they simply united with a portion of the air of the atmosphere.
When he first conceived this opinion he was ignorant of the nature
of atmospheric air, and of the existence of oxygen gas. But after
that principle had been discovered, and shown to be a constituent of
atmospherical air, he soon recognised that it was the union of oxygen
with the burning and calcining body that occasioned the phenomena. Such
is the outline of the Lavoisierian theory stated in the simplest and
fewest words. It will be requisite to make a few observations on the
much-agitated question whether this theory originated with him.

It is now well known that John Rey, a physician at Bugue, in Perigord,
published a book in 1630, in order to explain the cause of the increase
of weight which lead and tin experience during their calcination. After
refuting in succession all the different explanations of this increase
of weight which had been advanced, he adds, "To this question, then,
supported on the grounds already mentioned, I answer, and maintain
with confidence, that the increase of weight arises from the air,
which is condensed, rendered heavy and adhesive by the violent and
long-continued heat of the furnace. This air mixes itself with the calx
(frequent agitation conducing), and attaches itself to the minutest
molecules, in the same manner as water renders heavy sand which is
agitated with it, and moistens and adheres to the smallest grains."
There cannot be the least doubt from this passage that Rey's opinion
was precisely the same as the original one of Lavoisier, and had
Lavoisier done nothing more than merely state in general terms that
during calcination air unites with the calcining bodies, it might have
been suspected that he had borrowed his notions from those of Rey. But
the discovery of oxygen, and the numerous and decisive proofs which
he brought forward that during burning and calcination oxygen unites
with the burning and calcining body, and that this oxygen may be again
separated and exhibited in its original elastic state oblige us to
alter our opinion. And whether we admit that he borrowed his original
notion from Rey, or that it suggested itself to his own mind, the case
will not be materially altered. For it is not the man who forms the
first vague notion of a thing that really adds to the stock of our
knowledge, but he who demonstrates its truth and accurately determines
its nature.

Rey's book and his opinions were little known. He had not brought
over a single convert to his doctrine, a sufficient proof that he had
not established it by satisfactory evidence. We may therefore believe
Lavoisier's statement, when he assures us that when he first formed his
theory he was ignorant of Rey, and never had heard that any such book
had been published.

The theory of combustion advanced by Dr. Hook, in 1665, in his
Micrographia, approaches still nearer to that of Lavoisier than
the theory of Rey, and indeed, so far as he has explained it, the
coincidence is exact. According to Hook there exists in common air a
certain substance which is like, if not the very same with that which
is fixed in saltpetre. This substance has the property of dissolving
all combustibles; but only when their temperature is sufficiently
raised. The solution takes place with such rapidity that it occasions
fire, which in his opinion is mere _motion_. The dissolved substance
may be in the state of air, or coagulated in a liquid or solid form.
The quantity of this solvent in a given bulk of air is incomparably
less than in the same bulk of saltpetre. Hence the reason why a
combustible continues burning but a short time in a given bulk of air:
the solvent is soon saturated, and then of course the combustion is
at an end. This explains why combustion requires a constant supply
of fresh air, and why it is promoted by forcing in air with bellows.
Hook promised to develop this theory at greater length in a subsequent
work; but he never fulfilled his promise; though in his Lampas,
published about twelve years afterwards, he gives a beautiful chemical
explanation of flame, founded on the very same theory.

From the very general terms in which Hook expresses himself, we cannot
judge correctly of the extent of his knowledge. This theory, so far as
it goes, coincides exactly with our present notions on the subject.
His solvent is oxygen gas, which constitutes one-fifth part of the
volume of the air, but exists in much greater quantity in saltpetre.
It combines with the burning body, and the compound formed may either
be a gas, a liquid, or a solid, according to the nature of the body
subjected to combustion.

Lavoisier nowhere alludes to this theory of Hook nor gives the least
hint that he had ever heard of it. This is the more surprising,
because Hook was a man of great celebrity; and his Micrographia, as
containing the original figures and descriptions of many natural
objects, is well known, not merely in Great Britain, but on the
continent. At the same time it must be recollected that Hook's theory
is supported by no evidence; that it is a mere assertion, and that
nobody adopted it. Even then, if we were to admit that Lavoisier was
acquainted with this theory, it would derogate very little from his
merit, which consisted in investigating the phenomena of combustion and
calcination, and in showing that oxygen became a constituent of the
burnt and calcined bodies.

About ten years after the publication of the Micrographia, Dr. Mayow,
of Oxford, published his Essays. In the first of which, De Sal-nitro
et Spiritu Nitro-aëreo, he obviously adopts Dr. Hook's theory of
combustion, and he applies it with great ingenuity to explain the
nature of respiration. Dr. Mayow's book had been forgotten when the
attention of men of science was attracted to it by Dr. Beddoes. Dr.
Yeats, of Bedford, published a very interesting work on the merits of
Mayow, in 1798. It will be admitted at once by every person who takes
the trouble of perusing Mayow's tract, that he was not satisfied with
mere theory; but proved by actual experiment that air was absorbed
during combustion, and altered during respiration. He has given
figures of his apparatus, and they are very much of the same nature
with those afterwards made use of by Lavoisier. It would be wrong,
therefore, to deprive Mayow of the reputation to which he is entitled
for his ingeniously-contrived and well-executed experiments. It must be
admitted that he proved both the absorption of air during combustion
and respiration; but even this does not take much from the fair
fame of Lavoisier. The analysis of air and the discovery of oxygen
gas really diminish the analogy between the theories of Mayow and
Lavoisier, or at any rate the full investigation of the subject and the
generalization of it belong exclusively to Lavoisier.

Attempts were made by the other French chemists, about the beginning
of the revolution, to associate themselves with Lavoisier, as equally
entitled with himself to the merit of the antiphlogistic theory; but
Lavoisier himself has disclaimed the partnership. Some years before his
death, he had formed the plan of collecting together all his papers
relating to the antiphlogistic theory and publishing them in one work;
but his death interrupted the project. However, his widow afterwards
published the first two volumes of the book, which were complete at the
time of his death. In one of these volumes Lavoisier claims for himself
the exclusive discovery of the cause of the augmentation of weight
which bodies undergo during combustion and calcination. He informs us
that a set of experiments, which he made in 1772, upon the different
kinds of air which are disengaged in effervescence, and a great number
of other chemical operations discovered to him demonstratively the
cause of the augmentation of weight which metals experience when
exposed to heat. "I was young," says he, "I had newly entered the lists
of science, I was desirous of fame, and I thought it necessary to
take some steps to secure to myself the property of my discovery. At
that time there existed an habitual correspondence between the men of
science of France and those of England. There was a kind of rivality
between the two nations, which gave importance to new experiments,
and which sometimes was the cause that the writers of the one or the
other of the nations disputed the discovery with the real author.
Consequently, I thought it proper to deposit on the 1st of November,
1772, the following note in the hands of the secretary of the academy.
This note was opened on the 1st of May following, and mention of these
circumstances marked at the top of the note. It was in the following
terms:

"About eight days ago I discovered that sulphur in burning, far from
losing, augments in weight; that is to say, that from one pound of
sulphur much more than one pound of vitriolic acid is obtained, without
reckoning the humidity of the air. Phosphorus presents the same
phenomenon. This augmentation of weight arises from a great quantity of
air, which becomes fixed during the combustion, and which combines with
the vapours.

"This discovery, which I confirmed by experiments which I regard as
decisive, led me to think that what is observed in the combustion of
sulphur and phosphorus, might likewise take place with respect to all
the bodies which augment in weight by combustion and calcination;
and I was persuaded that the augmentation of weight in the calces of
metals proceeded from the same cause. The experiment fully confirmed my
conjectures. I operated the reduction of litharge in close vessels with
Hales's apparatus, and I observed, that at the moment of the passage
of the calx into the metallic state, there was a disengagement of air
in considerable quantity, and that this air formed a volume at least
one thousand times greater than that of the litharge employed. As this
discovery appears to me one of the most interesting which has been made
since Stahl, I thought it expedient to secure to myself the property,
by depositing the present note in the hands of the secretary of the
academy, to remain secret till the period when I shall publish my
experiments.

  "LAVOISIER.

"_Paris, November 11, 1772._"

This note leaves no doubt that Lavoisier had conceived his theory, and
confirmed it by experiment, at least as early as November, 1772. But at
that time the nature of air and the existence of oxygen were unknown.
The theory, therefore, as he understood it at that time, was precisely
the same as that of John Rey. It was not till the end of 1774 that his
views became more precise, and that he was aware that oxygen is the
portion of the air which unites with bodies during combustion, and
calcination.

Nothing can be more evident from the whole history of the academy,
and of the French chemists during this eventful period, for the
progress of the science, that none of them participated in the views
of Lavoisier, or had the least intention of giving up the phlogistic
theory. It was not till 1785, after his experiments had been almost all
published, and after all the difficulties had been removed by the two
great discoveries of Mr. Cavendish, that Berthollet declared himself a
convert to the Lavoisierian opinions. This was soon followed by others,
and within a very few years almost all the chemists and men of science
in France enlisted themselves on the same side. Lavoisier's objection,
then, to the phrase _La Chimie Française_, is not without reason, the
term _Lavoisierian Chemistry_ should undoubtedly be substituted for
it. This term, _La Chimie Française_ was introduced by Fourcroy. Was
Fourcroy anxious to clothe himself with the reputation of Lavoisier,
and had this any connexion with the violent death of that illustrious
man?

The first set of experiments which Lavoisier published on his peculiar
views, was entitled, "A Memoir on the Calcination of Tin in close
Vessels; and on the Cause of the increase of Weight which the Metal
acquires during this Process." It appeared in the Memoirs of the
Academy, for 1774. In this paper he gives an account of several
experiments which he had made on the calcination of tin in glass
retorts, hermetically sealed. He put a quantity of tin (about half a
pound) into a glass retort, sometimes of a larger and sometimes of a
smaller size, and then drew out the beak into a capillary tube. The
retort was now placed upon the sand-bath, and heated till the tin just
melted. The extremity of the capillary beak of the retort was now
fused so as to seal it hermetically. The object of this heating was to
prevent the retort from bursting by the expansion of the air during the
process. The retort, with its contents, was now carefully weighed, and
the weight noted. It was put again on the sand-bath, and kept melted
till the process of calcination refused to advance any further. He
observed, that if the retort was small, the calcination always stopped
sooner than it did if the retort was large. Or, in other words, the
quantity of tin calcined was always proportional to the size of the
retort.

After the process was finished, the retort (still hermetically sealed)
was again weighed, and was always found to have the same weight exactly
as at first. The beak of the retort was now broken off, and a quantity
of air entered with a hissing noise. The increase of weight was now
noted: it was obviously owing to the air that had rushed in. The weight
of air that had been at first driven out by the fusion of the tin had
been noted, and it was now found that a considerably greater quantity
had entered than had been driven out at first. In some experiments,
as much as 10·06 grains, in others 9·87 grains, and in some less than
this, when the size of the retort was small. The tin in the retort was
mostly unaltered, but a portion of it had been converted into a black
powder, weighing in some cases above two ounces. Now it was found in
all cases, that the weight of the tin had increased, and the increase
of weight was always exactly equal to the diminution of weight which
the air in the retort had undergone, measured by the quantity of new
air which rushed in when the beak of the retort was broken, minus the
air that had been driven out when the tin was originally melted before
the retort was hermetically sealed.

Thus Lavoisier proved by these first experiments, that when tin
is calcined in close vessels a portion of the air of the vessel
disappears, and that the tin increases in weight just as much as is
equivalent to the loss of weight which the air has sustained. He
therefore inferred, that this portion of air had united with the tin,
and that calx of tin is a compound of tin and air. In this first paper
there is nothing said about oxygen, nor any allusion to lead to the
suspicion that air is a compound of different elastic fluids. These,
therefore, were probably the experiments to which Lavoisier alludes in
the note which he lodged with the secretary of the academy in November,
1772.

He mentions towards the end of the Memoir that he had made similar
experiments with lead; but he does not communicate any of the numerical
results: probably because the results were not so striking as those
with tin. The heat necessary to melt lead is so high that satisfactory
experiments on its calcination could not easily be made in a glass
retort.

Lavoisier's next Memoir appeared in the Memoirs of the Academy, for
1775, which were published in 1778. It is entitled, "On the Nature of
the Principle which combines with the Metals during their Calcination,
and which augments their Weight." He observes that when the metallic
calces are reduced to the metallic state it is found necessary to
heat them along with charcoal. In such cases a quantity of carbonic
acid gas is driven off, which he assures us is the charcoal united to
the elastic fluid contained in the calx. He tried to reduce the calx
of iron by means of burning-glasses, while placed under large glass
receivers standing over mercury; but as the gas thus evolved was mixed
with a great deal of common air which was necessarily left in the
receiver, he was unable to determine its nature. This induced him to
have recourse to red oxide of mercury. He showed in the first place
that this substance (_mercurius præcipitatus per se_) was a true calx,
by mixing it with charcoal powder in a retort and heating it. The
mercury was reduced and abundance of carbonic acid gas was collected
in an inverted glass jar standing in a water-cistern into which the
beak of the retort was plunged. On heating the red oxide of mercury
by itself it was reduced to the metallic state, though not so easily,
and at the same time a gas was evolved which possessed the following
properties:

1. It did not combine with water by agitation.

2. It did not precipitate lime-water.

3. It did not unite with fixed or volatile alkalies.

4. It did not at all diminish their caustic quality.

5. It would serve again for the calcination of metals.

6. It was diminished like common air by addition of one-third of
nitrous gas.

7. It had none of the properties of carbonic acid gas. Far from being
fatal, like that gas, to animals, it seemed on the contrary more proper
for the purposes of respiration. Candles and burning bodies were not
only not extinguished by it, but burned with an enlarged flame in
a very remarkable manner. The light they gave was much greater and
clearer than in common air.

He expresses his opinion that the same kind of air would be obtained by
heating nitre without addition, and this opinion is founded on the fact
that when nitre is detonated with charcoal it gives out abundance of
carbonic acid gas.

Thus Lavoisier shows in this paper that the kind of air which unites
with metals during their calcination is purer and fitter for combustion
than common air. In short it is the gas which Dr. Priestley had
discovered in 1774, and which is now known by the name of oxygen gas.

This Memoir deserves a few animadversions. Dr. Priestley discovered
oxygen gas in August, 1774; and he informs us in his life, that in
the autumn of that year he went to Paris and exhibited to Lavoisier,
in his own laboratory the mode of obtaining oxygen gas by heating
red oxide of mercury in a gun-barrel, and the properties by which
this gas is distinguished--indeed the very properties which Lavoisier
himself enumerates in his paper. There can, therefore, be no doubt that
Lavoisier was acquainted with oxygen gas in 1774, and that he owed his
knowledge of it to Dr. Priestley.

There is some uncertainty about the date of Lavoisier's paper. In the
History of the Academy, for 1775, it is merely said about it, "Read at
the resumption (_rentrée_) of the Academy, on the 26th of April, by M.
Lavoisier," without naming the year. But it could not have been before
1775, because that is the year upon the volume of the Memoirs; and
besides, we know from the Journal de Physique (v. 429), that 1775 was
the year on which the paper of Lavoisier was read.

Yet in the whole of this paper the name of Dr. Priestley never occurs,
nor is the least hint given that he had already obtained oxygen gas by
heating red oxide of mercury. So far from it, that it is obviously the
intention of the author of the paper to induce his readers to infer
that he himself was the discoverer of oxygen gas. For after describing
the process by which oxygen gas was obtained by him, he says nothing
further remained but to determine its nature, and "I discovered with
_much surprise_ that it was not capable of combination with water
by agitation," &c. Now why the expression of surprise in describing
phenomena which had been already shown? And why the omission of all
mention of Dr. Priestley's name? I confess that this seems to me
capable of no other explanation than a wish to claim for himself the
discovery of oxygen gas, though he knew well that that discovery had
been previously made by another.

The next set of experiments made by Lavoisier to confirm or extend
his theory, was "On the Combustion of Phosphorus, and the Nature of
the Acid which results from that Combustion." It appeared in the
Memoirs of the Academy, for 1777. The result of these experiments
was very striking. When phosphorus is burnt in a given bulk of air
in sufficient quantity, about four-fifths of the volume of the air
disappears and unites itself with the phosphorus. The residual portion
of the air is incapable of supporting combustion or maintaining animal
life. Lavoisier gave it the name of _mouffette atmospherique_, and he
describes several of its properties. The phosphorus by combining with
the portion of air which has disappeared, is converted into phosphoric
acid, which is deposited on the inside of the receiver in which the
combustion is performed, in the state of fine white flakes. One grain
by this process is converted into two and a half grains of phosphoric
acid. These observations led to the conclusion that atmospheric air
is a mixture or compound of two distinct gases, the one (_oxygen_)
absorbed by burning phosphorus, the other (_azote_) not acted on by
that principle, and not capable of uniting with or calcining metals.
These conclusions had already been drawn by Scheele from similar
experiments, but Lavoisier was ignorant of them.

In the second part of this paper, Lavoisier describes the properties
of phosphoric acid, and gives an account of the salts which it forms
with the different bases. The account of these salts is exceedingly
imperfect, and it is remarkable that Lavoisier makes no distinction
between phosphate of potash and phosphate of soda; though the different
properties of these two salts are not a little striking. But these were
not the investigations in which Lavoisier excelled.

The next paper in which the doctrines of the antiphlogistic theory
were still further developed, was inserted in the Memoirs of the
Academy, for 1777. It is entitled, "On the Combustion of Candles in
atmospherical Air, and in Air eminently Respirable." This paper is
remarkable, because in it he first notices Dr. Priestley's discovery of
oxygen gas; but without any reference to the preceding paper, or any
apology for not having alluded in it to the information which he had
received from Dr. Priestley.

He begins by saying that it is necessary to distinguish four different
kinds of air. 1. Atmospherical air in which we live, and which we
breath. 2. Pure air (_oxygen_), alone fit for breathing, constituting
about the fourth of the volume of atmospherical air, and called by Dr.
Priestley _dephlogisticated air_. 3. Azotic gas, which constitutes
about three-fourths of the volume of atmospherical air, and whose
properties are still unknown. 4. Fixed air, which he proposed to call
(as Bucquet had done) _acide crayeux_, _acid of chalk_.

In this paper Lavoisier gives an account of a great many trials that
he made by burning candles in given volumes of atmospherical air and
oxygen gas enclosed in glass receivers, standing over mercury. The
general conclusion which he deduces from these experiments are--that
the azotic gas of the air contributes nothing to the burning of
the candle; but the whole depends upon the oxygen gas of the air,
constituting in his opinion one-fourth of its volume; that during the
combustion of a candle in a given volume of air only two-fifths of
the oxygen are converted into carbonic acid gas, while the remaining
three-fifths remain unaltered; but when the combustion goes on in
oxygen gas a much greater proportion (almost the whole) of this gas
is converted into carbonic acid gas. Finally, that phosphorus, when
burnt in air acts much more powerfully on the oxygen of the air than a
lighted candle, absorbing four-fifths of the oxygen and converting it
into phosphoric acid.

It is evident that at the time this paper was written, Lavoisier's
theory was nearly complete. He considered air as a mixture of three
volumes of azotic gas, and one volume of oxygen gas. The last alone
was concerned in combustion and calcination. During these processes a
portion of the oxygen united with the burning body, and the compound
formed constituted the acid or the calx. Thus he was able to account
for combustion and calcination without having recourse to phlogiston.
It is true that several difficulties still lay in his way, which he
was not yet able to obviate, and which prevented any other person from
adopting his opinions. One of the greatest of these was the fact that
hydrogen gas was evolved during the solution of several metals in
dilute sulphuric or muriatic acid; that by this solution these metals
were converted into calces, and that calces, when heated in hydrogen
gas, were reduced to the metallic state while the hydrogen disappeared.
The simplest explanation of these phenomena was the one adopted by
chemists at the time. Hydrogen was considered as phlogiston. By
dissolving metals in acids, the phlogiston was driven off and the calx
remained: by heating the calx in hydrogen, the phlogiston was again
absorbed and the calx reduced to the metallic state.

This explanation was so simple and appeared so satisfactory, that it
was universally adopted by chemists with the exception of Lavoisier
himself. There was a circumstance, however, which satisfied him that
this explanation, however plausible, was not correct. The calx was
_heavier_ than the metal from which it had been produced. And hydrogen,
though a light body, was still possessed of weight. It was obviously
impossible, then, that the metal could be a combination of the calx and
hydrogen. Besides, he had ascertained by direct experiment, that the
calces of mercury, tin, and lead are compounds of the respective metals
and oxygen. And it was known that when the other calces were heated
with charcoal, they were reduced to the metallic state, and at the same
time carbonic acid gas is evolved. The very same evolution takes place
when calces of mercury, tin, and lead, are heated with charcoal powder.
Hence the inference was obvious that carbonic acid is a compound of
charcoal and oxygen, and therefore that all calces are compounds of
their respective metals and oxygen.

Thus, although Lavoisier was unable to account for the phenomena
connected with the evolution and absorption of hydrogen gas, he had
conclusive evidence that the orthodox explanation was not the true one.
He wisely, therefore, left it to time to throw light upon those parts
of the theory that were still obscure.

His next paper, which was likewise inserted in the Memoirs of the
Academy, for 1777, had some tendency to throw light on this subject,
or at least it elucidated the constitution of sulphuric acid, which
bore directly upon the antiphlogistic theory. It was entitled, "On the
Solution of Mercury in vitriolic Acid, and on the Resolution of that
Acid into aeriform sulphurous Acid, and into Air eminently Respirable."

He had already proved that sulphuric acid is a compound of sulphur and
oxygen; and had even shown how the oxygen which the acid contained
might be again separated from it, and exhibited in a separate state.
Dr. Priestley had by this time made known the method of procuring
sulphurous acid gas, by heating a mixture of mercury and sulphuric
acid in a phial. This was the process which Lavoisier analyzed in the
present paper. He put into a retort a mixture of four ounces mercury
and six ounces concentrated sulphuric acid. The beak of the retort was
plunged into a mercurial cistern, to collect the sulphurous acid gas
as it was evolved; and heat being applied to the belly of the retort,
sulphurous acid gas passed over in abundance, and sulphate of mercury
was formed. The process was continued till the whole liquid contents
of the retort had disappeared: then a strong heat was applied to the
salt. In the first place, a quantity of sulphurous acid gas passed
over, and lastly a portion of oxygen gas. The quicksilver was reduced
to the metallic state. Thus he resolved sulphuric acid into sulphurous
acid and oxygen. Hence it followed as a consequence, that sulphurous
acid differs from sulphuric merely by containing a smaller quantity of
oxygen.

The object of his next paper, published at the same time, was to throw
light upon the pyrophorus of Homberg, which was made by kneading
alum into a cake, with flour, or some substance containing abundance
of carbon, and then exposing the mixture to a strong heat in close
vessels, till it ceased to give out smoke. It was known that a
pyrophorus thus formed takes fire of its own accord, and burns when it
comes in contact with common air. It will not be necessary to enter
into a minute analysis of this paper, because, though the experiments
were very carefully made, yet it was impossible, at the time when the
paper was drawn, to elucidate the phenomena of this pyrophorus in a
satisfactory manner. There can be little doubt that the pyrophorus owes
its property of catching fire, when in contact with air or oxygen,
to a little potassium, which has been reduced to the metallic state
by the action of the charcoal and sulphur on the potash in the alum.
This substance taking fire, heat enough is produced to set fire to the
carbon and sulphur which the pyrophorus contains. Lavoisier ascertained
that during its combustion a good deal of carbonic acid was generated.

There appeared likewise another paper by Lavoisier, in the same volume
of the academy, which may be mentioned, as it served still further to
demonstrate the truth of the antiphlogistic theory. It is entitled, "On
the Vitriolization of Martial Pyrites." Iron pyrites is known to be a
compound of _iron_ and _sulphur_. Sometimes this mineral may be left
exposed to the air without undergoing any alteration, while at other
times it speedily splits, effloresces, swells, and is converted into
sulphate of iron. There are two species of pyrites; the one composed
of two atoms of sulphur and one atom of iron, the other of one atom of
sulphur and one atom of iron. The first of these is called bisulphuret
of iron; the second protosulphuret, or simply sulphuret of iron. The
variety of pyrites which undergoes spontaneous decomposition in the
air, is known to be a compound, or rather mixture of the two species of
pyrites.

Lavoisier put a quantity of the decomposing pyrites under a glass jar,
and found that the process went on just as well as in the open air.
He found that the air was deprived of the whole of its oxygen by the
process, and that nothing was left but azotic gas. Hence the nature
of the change became evident. The sulphur, by uniting with oxygen,
was converted into sulphuric acid, while the iron became oxide of
iron, and both uniting, formed sulphate of iron. There are still some
difficulties connected with this change that require to be elucidated.

We have still another paper by Lavoisier, bearing on the antiphlogistic
theory, published in the same volume of the Memoirs of the Academy,
for 1778, entitled, "On Combustion in general." He establishes that
the only air capable of supporting combustion is oxygen gas: that
during the burning of bodies in common air, a portion of the oxygen of
the atmosphere disappears, and unites with the burning body, and that
the new compound formed is either an acid or a metallic calx. When
sulphur is burnt, sulphuric acid is formed; when phosphorus, phosphoric
acid; and when charcoal, carbonic acid. The calcination of metals is
a process analogous to combustion, differing chiefly by the slowness
of the process: indeed when it takes place rapidly, actual combustion
is produced. After establishing these general principles, which are
deduced from his preceding papers, he proceeds to examine the Stahlian
theory of phlogiston, and shows that no evidence of the existence of
any such principle can be adduced, and that the phenomena can all be
explained without having recourse to it. Powerful as these arguments
were, they produced no immediate effects. Nobody chose to give up the
phlogistic theory to which he had been so long accustomed.

The next two papers of Lavoisier require merely to be mentioned, as
they do not bear immediately upon the antiphlogistic theory. They
appeared in the Memoirs of the Academy, for 1780. These memoirs were,

1. Second Memoir on the different Combinations of Phosphoric Acid.

2. On a particular Process, by means of which Phosphorus may be
converted into phosphoric Acid, without Combustion.

The process here described consisted in throwing phosphorus, by a
few grains at a time, into warm nitric acid of the specific gravity
1·29895. It falls to the bottom like melted wax, and dissolves pretty
rapidly with effervescence: then another portion is thrown in, and the
process is continued till as much phosphorus has been employed as is
wanted; then the phosphoric acid may be obtained pure by distilling off
the remaining nitric acid with which it is still mixed.

Hitherto Lavoisier had been unable to explain the anomalies respecting
hydrogen gas, or to answer the objections urged against his theory
in consequence of these anomalies. He had made several attempts to
discover what peculiar substance was formed during the combustion of
hydrogen, but always without success: at last, in 1783, he resolved to
make the experiment upon so large a scale, that whatever the product
might be, it should not escape him; but Sir Charles Blagden, who
had just gone to Paris, informed him that the experiment for which
he was preparing had already been made by Mr. Cavendish, who had
ascertained that the product of the combustion of hydrogen was _water_.
Lavoisier saw at a glance the vast importance of this discovery for
the establishment of the antiphlogistic theory, and with what ease it
would enable him to answer all the plausible objections which had been
brought forward against his opinions in consequence of the evolution
of hydrogen, when metals were calcined by solution in acids, and the
absorption of it when metals were reduced in an atmosphere of this
gas. He therefore resolved to repeat the experiment of Cavendish with
every possible care, and upon a scale sufficiently large to prevent
ambiguity. The experiment was made on the 24th of June, 1783, by
Lavoisier and Laplace, in the presence of M. Le Roi, M. Vandermonde,
and Sir Charles Blagden, who was at that time secretary of the Royal
Society. The quantity of water formed was considerable, and they found
that water was a compound of

  1 volume oxygen
  1·91 volume hydrogen.

Not satisfied with this, he soon after made another experiment along
with M. Meusnier to decompose water. For this purpose a porcelain tube,
filled with iron wire, was heated red-hot by being passed through a
furnace, and then the steam of water was made to traverse the red-hot
wire. To the further extremity of the porcelain tube a glass tube was
luted, which terminated in a water-trough under an inverted glass
receiver placed to collect the gas. The steam was decomposed by the
red-hot iron wire, its oxygen united to the wire, while the hydrogen
passed on and was collected in the water-cistern.

Both of these experiments, though not made till 1783, and though the
latter of them was not read to the academy till 1784, were published in
the volume of the Memoirs for 1781.

It is easy to see how this important discovery enabled Lavoisier to
obviate all the objections to his theory from hydrogen. He showed that
it was evolved when zinc or iron was dissolved in dilute sulphuric
acid, because the water underwent decomposition, its oxygen uniting to
the zinc or iron, and converting it into an oxide, while its hydrogen
made its escape in the state of gas. Oxide of iron was reduced when
heated in contact with hydrogen gas, because the hydrogen united to
the oxygen of the acid and formed water, and of course the iron was
reduced to the state of a metal. I consider it unnecessary to enter
into a minute detail of these experiments, because, in fact, they
added very little to what had been already established by Cavendish.
But it was this discovery that contributed more than any thing else
to establish the antiphlogistic theory. Accordingly, the great object
of Dr. Priestley, and other advocates of the phlogistic theory, was
to disprove the fact that water is a compound of oxygen and hydrogen.
Scheele admitted the fact that water is a compound of oxygen and
hydrogen; and doubtless, had he lived, would have become a convert
to the antiphlogistic theory, as Dr. Black actually did. In short,
it was the discovery of the compound nature of water that gave the
Lavoisierian theory the superiority over that of Stahl. Till the time
of this discovery every body opposed the doctrine of Lavoisier; but
within a very few years after it, hardly any supporters of phlogiston
remained. Nothing could be more fortunate for Lavoisier than this
discovery, or afford him greater reason for self-congratulation.

We see the effect of this discovery upon his next paper, "On the
Formation of Carbonic Acid," which appeared in the Memoirs of the
Academy, for 1781. There, for the first time, he introduces new terms,
showing, by that, that he considered his opinions as fully established.
To the _dephlogisticated air_ of Priestley, or his own _pure air_, he
now gives the name of _oxygen_. The fixed air of Black he designates
_carbonic acid_, because he considered it as a compound of _carbon_
(the pure part of charcoal) and oxygen. The object of this paper is to
determine the proportion of the constituents. He details a great many
experiments, and deduces from them all, that carbonic acid gas is a
compound of

  Carbon   0·75
  Oxygen   1·93

Now this is a tolerably near approximation to the truth. The true
constituents, as determined by modern chemists, being

  Carbon   0·75
  Oxygen   2·00

The next paper of M. Lavoisier, which appeared in the Memoirs of the
Academy, for 1782 (published in 1785), shows how well he appreciated
the importance of the discovery of the composition of water. It is
entitled, "General Considerations on the Solution of the Metals in
Acids." He shows that when metals are dissolved in acids, they are
converted into oxides, and that the acid does not combine with the
metal, but only with its oxide. When nitric acid is the solvent the
oxidizement takes place at the expense of the acid, which is resolved
into nitrous gas and oxygen. The nitrous gas makes its escape, and may
be collected; but the oxygen unites with the metal and renders it an
oxide. He shows this with respect to the solution of mercury in nitric
acid. He collected the nitrous gas given out during the solution of
the metal in the acid: then evaporated the solution to dryness, and
urged the fire till the mercury was converted into red oxide. The fire
being still further urged, the red oxide was reduced, and the oxygen
gas given off was collected and measured. He showed that the nitrous
gas and the oxygen gas thus obtained, added together, formed just the
quantity of nitric acid which had disappeared during the process. A
similar experiment was made by dissolving iron in nitric acid, and then
urging the fire till the iron was freed from every foreign body, and
obtained in the state of black oxide.

It is well known that many metals held in solution by acids may be
precipitated in the metallic state, by inserting into the solution
a plate of some other metal. A portion of that new metal dissolves,
and takes the place of the metal originally in solution. Suppose, for
example, that we have a neutral solution of copper in sulphuric acid,
if we put into the solution a plate of iron, the copper is thrown down
in the metallic state, while a certain portion of the iron enters into
the solution, combining with the acid instead of the copper. But the
copper, while in solution, was in the state of an oxide, and it is
precipitated in the metallic state. The iron was in the metallic state;
but it enters into the solution in the state of an oxide. It is clear
from this that the oxygen, during these precipitations, shifts its
place, leaving the copper, and entering into combination with the iron.
If, therefore, in such a case we determine the exact quantity of copper
thrown down, and the exact quantity of iron dissolved at the same time,
it is clear that we shall have the relative weight of each combined
with the same weight of oxygen. If, for example, 4 of copper be thrown
down by the solution of 3·5 of iron; then it is clear that 3·5 of iron
requires just as much oxygen as 4 of copper, to turn both into the
oxide that exists in the solution, which is the black oxide of each.

Bergman had made a set of experiments to determine the proportional
quantities of phlogiston contained in the different metals, by the
relative quantity of each necessary to precipitate a given weight
of another from its acid solution. It was the opinion at that time,
that metals were compounds of their respective calces and phlogiston.
When a metal dissolved in an acid, it was known to be in the state
of calx, and therefore had parted with its phlogiston: when another
metal was put into this solution it became a calx, and the dissolved
metal was precipitated in the metallic state. It had therefore united
with the phlogiston of the precipitating metal. It is obvious, that
by determining the quantities of the two metals precipitated and
dissolved, the relative proportion of phlogiston in each could be
determined. Lavoisier saw that these experiments of Bergman would serve
equally to determine the relative quantity of oxygen in the different
oxides. Accordingly, in a paper inserted in the Memoirs of the Academy,
for 1782, he enters into an elaborate examination of Bergman's
experiments, with a view to determine this point. But it is unnecessary
to state the deductions which he drew, because Bergman's experiments
were not sufficiently accurate for the object in view. Indeed, as
the mutual precipitation of the metals is a galvanic phenomenon, and
as the precipitated metal is seldom quite pure, but an alloy of the
precipitating and precipitated metal; and as it is very difficult
to dry the more oxidizable metals, as copper and tin, without their
absorbing oxygen when they are in a state of very minute division;
this mode of experimenting is not precise enough for the object which
Lavoisier had in view. Accordingly the table of the composition of the
metallic oxides which Lavoisier has drawn up is so very defective, that
it is not worth while to transcribe it.

The same remark applies to the table of the affinities of oxygen which
Lavoisier drew up and inserted in the Memoirs of the Academy, for the
same year. His data were too imperfect, and his knowledge too limited,
to put it in his power to draw up any such table with any approach to
accuracy. I shall have occasion to resume the subject in a subsequent
chapter.

In the same volume of the Memoirs of the Academy, this indefatigable
man inserted a paper in order to determine the quantity of oxygen
which combines with iron. His method of proceeding was, to burn a
given weight of iron in oxygen gas. It is well known that iron wire,
under such circumstances, burns with considerable splendour, and that
the oxide, by the heat, is fused into a black brittle matter, having
somewhat of the metallic lustre. He burnt 145·6 grains of iron in this
way, and found that, after combustion, the weight became 192 grains,
and 97 French cubic inches of oxygen gas had been absorbed. From this
experiment it follows, that the oxide of iron formed by burning iron in
oxygen gas is a compound of

  Iron   3·5
  Oxygen 1·11

This forms a tolerable approximation to the truth. It is now
known, that the quantity of oxygen in the oxide of iron formed by
the combustion of iron in oxygen gas is not quite uniform in its
composition; sometimes it is a compound of

  Iron   3½
  Oxygen 1⅓

While at other times it consists very nearly of

  Iron   3·5
  Oxygen 1

and probably it may exist in all the intermediate proportions between
these two extremes. The last of these compounds constitutes what is
now known by the name of _protoxide_, or _black oxide of iron_. The
first is the composition of the ore of iron so abundant, which is
distinguished by the name of _magnetic iron ore_.

Lavoisier was aware that iron combines with more oxygen than exists
in the protoxide; indeed, his analysis of peroxide of iron forms a
tolerable approximation to the truth; but there is no reason for
believing that he was aware that iron is capable of forming only two
oxides, and that all intermediate degrees of oxidation are impossible.
This was first demonstrated by Proust.

I think it unnecessary to enter into any details respecting two papers
of Lavoisier, that made their appearance in the Memoirs of the Academy,
for 1783, as they add very little to what he had already done. The
first of these describes the experiments which he made to determine the
quantity of oxygen which unites with sulphur and phosphorus when they
are burnt: it contains no fact which he had not stated in his former
papers, unless we are to consider his remark, that the heat given out
during the burning of these bodies has no sensible weight, as new.

The other paper is "On Phlogiston;" it is very elaborate, but contains
nothing which had not been already advanced in his preceding memoirs.
Chemists were so wedded to the phlogistic theory, their prejudices
were so strong, and their understandings so fortified against every
thing that was likely to change their opinions, that Lavoisier found
it necessary to lay the same facts before them again and again, and to
place them in every point of view. In this paper he gives a statement
of his own theory of combustion, which he had previously done in
several preceding papers. He examines the phlogistic theory of Stahl at
great length, and refutes it.

In the Memoirs of the Academy, for 1784, Lavoisier published a very
elaborate set of experiments on the combustion of alcohol, oil, and
different combustible bodies, which gave a beginning to the analysis
of vegetable substances, and served as a foundation upon which this
most difficult part of chemistry might be reared. He showed that during
the combustion of alcohol the oxygen of the air united to the vapour
of the alcohol, which underwent decomposition, and was converted
into water and carbonic acid. From these experiments he deduced as a
consequence, that the constituents of alcohol are carbon, hydrogen,
and oxygen, and nothing else; and he endeavoured from his experiments
to determine the relative proportions of these different constituents.
From these experiments he concluded, that the alcohol which he used in
his experiments was a compound of

  Carbon     2629·5 part.
  Hydrogen    725·5
  Water      5861

It would serve no purpose to attempt to draw any consequences from
these experiments; as Lavoisier does not mention the specific gravity
of the alcohol, of course we cannot say how much of the water found
was merely united with the alcohol, and how much entered into
its composition. The proportion between the carbon and hydrogen,
constitutes an approximation to the truth, though not a very near one.

Olive oil he showed to be a compound of hydrogen and carbon, and bees'
wax to be a compound of the same constituents, though in a different
proportion.

This subject was continued, and his views further extended, in a
paper inserted in the Memoirs of the Academy, for 1786, entitled,
"Reflections on the Decomposition of Water by Vegetable and Animal
Substances." He begins by stating that when charcoal is exposed to
a strong heat, it gives out a little carbonic acid gas and a little
inflammable air, and after this nothing more can be driven off, however
high the temperature be to which it is exposed; but if the charcoal
be left for some time in contact with the atmosphere it will again
give out a little carbonic acid gas and inflammable gas when heated,
and this process may be repeated till the whole charcoal disappears.
This is owing to the presence of a little moisture which the charcoal
imbibes from the air. The water is decomposed when the charcoal is
heated and converted into carbonic acid and inflammable gas. When
vegetable substances are heated in a retort, the water which they
contain undergoes a similar decomposition, the carbon which forms one
of their constituents combines with the oxygen and produces carbonic
acid, while the hydrogen, the other constituent of the water, flies
off in the state of gas combined with a certain quantity of carbon.
Hence the substances obtained when vegetable or animal substances
are distilled did not exist ready formed in the body operated on;
but proceeded from the double decompositions which took place by the
mutual action of the constituents of the water, sugar, mucus, &c.,
which the vegetable body contains. The oil, the acid, &c., extracted
by distilling vegetable bodies did not exist in them, but are formed
during the mutual action of the constituents upon each other,
promoted as their action is by the heat. These views were quite new
and perfectly just, and threw a new light on the nature of vegetable
substances and on the products obtained by distilling them. It showed
the futility of all the pretended analyses of vegetable substances,
which chemists had performed by simply subjecting them to distillation,
and the error of drawing any conclusions respecting the constituents
of vegetable substances from the results of their distillation, except
indeed with respect to their elementary constituents. Thus when by
distilling a vegetable substance we obtain water, oil, acetic acid,
carbonic acid, and carburetted hydrogen, we must not conclude that
these principles existed in the substance, but merely that it contained
carbon, hydrogen, and oxygen, in such proportions as to yield all these
principles by decompositions.

As nitric acid acts upon metals in a very different way from sulphuric
and muriatic acids, and as it is a much better solvent of metals in
general than any other, it was an object of great importance towards
completing the antiphlogistic theory to obtain an accurate knowledge
of its constituents. Though Lavoisier did not succeed in this, yet he
made at least a certain progress, which enabled him to explain the
phenomena, at that time known, with considerable clearness, and to
answer all the objections to the antiphlogistic theory from the action
of nitric acid on metals. His first paper on the subject was published
in the Memoirs of the Academy, for 1776. He put a quantity of nitric
acid and mercury into a retort with a long beak, which he plunged into
the water-trough. An effervescence took place and gas passed over
in abundance, and was collected in a glass jar; the mercury being
dissolved the retort was still further heated, till every thing liquid
passed over into the receiver, and a dry yellow salt remained. The beak
of the retort was now again plunged into the water-trough, and the salt
heated till all the nitric acid which it contained was decomposed,
and nothing remained in the retort but red oxide of mercury. During
this last process much more gas was collected. All the gas obtained
during the solution of the mercury and the decomposition of the salt
was nitrous gas. The red oxide of mercury was now heated to redness,
oxygen gas was emitted in abundance, and the mercury was reduced to the
metallic state: its weight was found the very same as at first. It is
clear, therefore, that the nitrous gas and the oxygen gas were derived,
not from the mercury but from the nitric acid, and that the nitric acid
had been decomposed into nitrous gas and oxygen: the nitrous gas had
made its escape in the form of gas, and the oxygen had remained united
to the metal.

From these experiments it follows clearly, that nitric acid is a
compound of nitrous gas and oxygen. The nature of nitrous gas itself
Lavoisier did not succeed in ascertaining. It passed with him for a
simple substance; but what he did ascertain enabled him to explain
the action of nitric acid on metals. When nitric acid is poured upon
a metal which it is capable of dissolving, copper for example, or
mercury, the oxygen of the acid unites to the metal, and converts into
an oxide, while the nitrous gas, the other constituent of the acid,
makes its escape in the gaseous form. The oxide combines with and is
dissolved by another portion of the acid which escapes decomposition.

It was discovered by Dr. Priestley, that when nitrous gas and oxygen
gas are mixed together in certain proportions, they instantly unite,
and are converted into nitrous acid. If this mixture be made over
water, the volume of the gases is instantly diminished, because the
nitrous acid formed loses its elasticity, and is absorbed by the
water. When nitrous gas is mixed with air containing oxygen gas, the
diminution of volume after mixture is greater the more oxygen gas is
present in the air. This induced Dr. Priestley to employ nitrous gas as
a test of the purity of common air. He mixed together equal volumes of
the nitrous gas and air to be examined, and he judged of the purity
of the air by the degree of condensation: the greater the diminution
of bulk, the greater did he consider the proportion of oxygen in the
air under examination to be. This method of proceeding was immediately
adopted by chemists and physicians; but there was a want of uniformity
in the mode of proceeding, and a considerable diversity in the results.
M. Lavoisier endeavoured to improve the process, in a paper inserted
in the Memoirs of the Academy, for 1782; but his method did not answer
the purpose intended: it was Mr. Cavendish that first pointed out an
accurate mode of testing air by means of nitrous gas, and who showed
that the proportions of oxygen and azotic gas in common air are
invariable.

Lavoisier, in the course of his investigations, had proved that
carbonic acid is a compound of carbon and oxygen; sulphuric acid,
of sulphur and oxygen; phosphoric acid, of phosphorus and oxygen;
and nitric acid, of nitrous gas and oxygen. Neither the carbon, the
sulphur, the phosphorus, nor the nitrous gas, possessed any acid
properties when uncombined; but they acquired these properties when
they were united to oxygen. He observed further, that all the acids
known in his time which had been decomposed were found to contain
oxygen, and when they were deprived of oxygen, they lost their acid
properties. These facts led him to conclude, that oxygen is an
essential constituent in all acids, and that it is the principle
which bestows acidity or the true acidifying principle. This was the
reason why he distinguished it by the name of oxygen.[5] These views
were fully developed by Lavoisier, in a paper inserted in the Memoirs
of the Academy, for 1778, entitled, "General Considerations on the
Nature of Acids, and on the Principles of which they are composed."
When this paper was published, Lavoisier's views were exceedingly
plausible. They were gradually adopted by chemists in general, and
for a number of years may be considered to have constituted a part of
the generally-received doctrines. But the discovery of the nature of
chlorine, and the subsequent facts brought to light respecting iodine,
bromine, and cyanogen, have demonstrated that it is inaccurate; that
many powerful acids exist which contain no oxygen, and that there is
no one substance to which the name of acidifying principle can with
justice be given. To this subject we shall again revert, when we come
to treat of the more modern discoveries.

 [5] From ὀξυς, sour, and γινομαι, which he defined the _producer of
 acids_, the _acidifying principle_.

Long as the account is which we have given of the labours of Lavoisier,
the subject is not yet exhausted. Two other papers of his remain to be
noticed, which throw considerable light on some important functions
of the living body: we allude to his experiments on _respiration_ and
_perspiration_.

It was known, that if an animal was confined beyond a certain limited
time in a given volume of atmospherical air, it died of suffocation,
in consequence of the air becoming unfit for breathing; and that
if another animal was put into this air, thus rendered noxious by
breathing, its life was destroyed almost in an instant. Dr. Priestley
had thrown some light upon this subject by showing that air, in which
an animal had breathed for some time, possessed the property of
rendering lime-water turbid, and therefore contained carbonic acid gas.
He considered the process of breathing as exactly analogous to the
calcination of metals, or the combustion of burning bodies. Both, in
his opinion acted by giving out phlogiston; which, uniting with the
air of the atmosphere, converted it into phlogisticated air. Priestley
found, that if plants were made to vegetate for some time in air that
had been rendered unfit for supporting animal life by respiration,
it lost the property of extinguishing a candle, and animals could
breathe it again without injury. He concluded from this that animals,
by breathing, phlogisticated air, but that plants, by vegetating,
dephlogisticated air: the former communicated phlogiston to it, the
latter took phlogiston from it.

After Lavoisier had satisfied himself that air is a mixture of oxygen
and azote, and that oxygen alone is concerned in the processes of
calcination and combustion, being absorbed and combined with the
substances undergoing calcination and combustion, it was impossible for
him to avoid drawing similar conclusions with respect to the breathing
of animals. Accordingly, he made experiments on the subject, and the
result was published in the Memoirs of the Academy, for 1777. From
these experiments he drew the following conclusions:

1. The only portion of atmospherical air which is useful in breathing
is the oxygen. The azote is drawn into the lungs along with the oxygen,
but it is thrown out again unaltered.

2. The oxygen gas, on the contrary, is gradually, by breathing,
converted into carbonic acid; and air becomes unfit for respiration
when a certain portion of its oxygen is converted into carbonic acid
gas.

3. Respiration is therefore exactly analogous to calcination. When air
is rendered unfit for supporting life by respiration, if the carbonic
acid gas formed be withdrawn by means of lime-water, or caustic alkali,
the azote remaining is precisely the same, in its nature, as what
remains after air is exhausted of its oxygen by being employed for
calcining metals.

In this first paper Lavoisier went no further than establishing these
general principles; but he afterwards made experiments to determine the
exact amount of the changes which were produced in air by breathing,
and endeavoured to establish an accurate theory of respiration. To this
subject we shall have occasion to revert again, when we give an account
of the attempts made to determine the phenomena of respiration by more
modern experimenters.

Lavoisier's experiments on _perspiration_ were made during the frenzy
of the French revolution, when Robespierre had usurped the supreme
power, and when it was the object of those at the head of affairs
to destroy all the marks of civilization and science which remained
in the country. His experiments were scarcely completed when he was
thrown into prison, and though he requested a prolongation of his
life for a short time, till he could have the means of drawing up a
statement of their results, the request was barbarously refused. He has
therefore left no account of them whatever behind him. But Seguin, who
was associated with him in making these experiments, was fortunately
overlooked, and escaped the dreadful times of the reign of terror: he
afterwards drew up an account of the results, which has prevented them
from being wholly lost to chemists and physiologists.

Seguin was usually the person experimented on. A varnished silk bag,
perfectly air-tight, was procured, within which he was enclosed, except
a slit over against the mouth, which was left open for breathing; and
the edges of the bag were accurately cemented round the mouth, by
means of a mixture of turpentine and pitch. Thus every thing emitted
by the body was retained in the bag, except what made its escape from
the lungs by respiration. By weighing himself in a delicate balance at
the commencement of the experiment, and again after he had continued
for some time in the bag, the quantity of matter carried off by
respiration was determined. By weighing himself without this varnished
covering, and repeating the operation after the same interval of time
had elapsed, as in the former experiment, he determined the loss of
weight occasioned by _perspiration_ and _respiration_ together. The
loss of weight indicated by the first experiment being subtracted from
that given by the second, the quantity of matter lost by _perspiration_
through the pores of the skin was determined. The following facts were
ascertained by these experiments:

1. The maximum of matter perspired in a minute amounted to 26·25 grains
troy; the minimum to nine grains; which gives 17·63 grains, at a
medium, in the minute, or 52·89 ounces in twenty-four hours.

2. The amount of perspiration is increased by drink, but not by solid
food.

3. Perspiration is at its minimum immediately after a repast; it
reaches its maximum during digestion.

Such is an epitome of the chemical labours of M. Lavoisier. When we
consider that this prodigious number of experiments and memoirs were
all performed and drawn up within the short period of twenty years,
we shall be able to form some idea of the almost incredible activity
of this extraordinary man: the steadiness with which he kept his own
peculiar opinions in view, and the good temper which he knew how to
maintain in all his publications, though his opinions were not only
not supported, but actually opposed by the whole body of chemists in
existence, does him infinite credit, and was undoubtedly the wisest
line of conduct which he could possibly have adopted. The difficulties
connected with the evolution and absorption of hydrogen, constituted
the stronghold of the phlogistians. But Mr. Cavendish's discovery, that
water is a compound of oxygen and hydrogen, was a death-blow to the
doctrine of Stahl. Soon after this discovery was fully established, or
during the year 1785, M. Berthollet, a member of the academy, and fast
rising to the eminence which he afterwards acquired, declared himself
a convert to the Lavoisierian theory. His example was immediately
followed by M. Fourcroy, also a member of the academy, who had
succeeded Macquer as professor of chemistry in the Jardin du Roi.

M. Fourcroy, who was perfectly aware of the strong feeling of
patriotism which, at that time, actuated almost every man of science
in France, hit upon a most infallible way of giving currency to the
new opinions. To the theory of Lavoisier he gave the name of _La
Chimie Française_ (French Chemistry). This name was not much relished
by Lavoisier, as, in his opinion, it deprived him of the credit which
was his due; but it certainly contributed, more than any thing else,
to give the new opinions currency, at least, in France; they became
at once a national concern, and those who still adhered to the old
opinions, were hooted and stigmatized as enemies to the glory of their
country. One of the most eminent of those who still adhered to the
phlogistic theory was M. Guyton de Morveau, a nobleman of Burgundy, who
had been educated as a lawyer, and who filled a conspicuous situation
in the Parliament of Dijon: he had cultivated chemistry with great
zeal, and was at that time the editor of the chemical part of the
Encyclopédie Méthodique. In the first half-volume of the chemical part
of this dictionary, which had just appeared, Morveau had supported the
doctrine of phlogiston, and opposed the opinions of Lavoisier with much
zeal and considerable skill: on this account, it became an object of
considerable consequence to satisfy Morveau that his opinions were
inaccurate, and to make him a convert to the antiphlogistic theory; for
the whole matter was managed as if it had been a political intrigue,
rather than a philosophical inquiry.

Morveau was accordingly invited to Paris, and Lavoisier succeeded
without difficulty in bringing him over to his own opinions. We are
ignorant of the means which he took; no doubt friendly discussion
and the repetition of the requisite experiments, would be sufficient
to satisfy a man so well acquainted with the subject, and whose mode
of thinking was so liberal as Morveau. Into the middle of the second
half-volume of the chemical part of the Encyclopédie Méthodique
he introduced a long advertisement, announcing this change in his
opinions, and assigning his reasons for it.

The chemical nomenclature at that time in use had originated with
the medical chemists, and contained a multiplicity of unwieldy and
unmeaning, and even absurd terms. It had answered the purposes of
chemists tolerably well while the science was in its infancy; but the
number of new substances brought into view had of late years become
so great, that the old names could not be applied to them without
the utmost straining: and the chemical terms in use were so little
systematic that it required a considerable stretch of memory to retain
them. These evils were generally acknowledged and lamented, and
various attempts had been made to correct them. Bergman, for instance,
had contrived a new nomenclature, confined chiefly to the salts and
adapted to the Latin language. Dr. Black had done the same thing: his
nomenclature possessed both elegance and neatness, and was, in several
respects, superior to the terms ultimately adopted; but with his usual
indolence and disregard of reputation, he satisfied himself merely with
drawing it up in the form of a table and exhibiting it to his class.
Morveau contrived a new nomenclature of the salts, and published it in
1783; and it appears to have been seen and approved of by Bergman.

The old chemical phraseology as far as it had any meaning was entirely
conformable to the phlogistic theory. This was so much the case that
it was with difficulty that Lavoisier was able to render his opinions
intelligible by means of it. Indeed it would have been out of his power
to have conveyed his meaning to his readers, had he not invented and
employed a certain number of new terms. Lavoisier, aware of the defects
of the chemical nomenclature, and sensible of the advantage which his
own doctrine would acquire when dressed up in a language exactly suited
to his views, was easily prevailed upon by Morveau to join with him in
forming a new nomenclature to be henceforth employed exclusively by
the antiphlogistians, as they called themselves. For this purpose they
associated with themselves Berthollet, and Fourcroy. We do not know
what part each took in this important undertaking; but, if we are to
judge from appearances, the new nomenclature was almost exclusively
the work of Lavoisier and Morveau. Lavoisier undoubtedly contrived the
general phrases, and the names applied to the simple substances, so far
as they were new, because he had employed the greater number of them in
his writings before the new nomenclature was concocted. That the mode
of naming the salts originated with Morveau is obvious; for it differs
but little from the nomenclature of the salts published by him four
years before.

The new nomenclature was published by Lavoisier and his associates in
1787, and it was ever after employed by them in all their writings.
Aware of the importance of having a periodical work in which they could
register and make known their opinions, they established the _Annales
de Chimie_, as a sort of counterpoise to the _Journal de Physique_,
the editor of which, M. Delametherie, continued a zealous votary of
phlogiston to the end of his life. This new nomenclature very soon made
its way into every part of Europe, and became the common language of
chemists, in spite of the prejudices entertained against it, and the
opposition which it every where met with. In the year 1796, or nine
years after the appearance of the new nomenclature, when I attended the
chemistry-class in the College of Edinburgh, it was not only in common
use among the students, but was employed by Dr. Black, the professor
of chemistry, himself; and I have no doubt that he had introduced it
into his lectures several years before. This extraordinary rapidity
with which the new chemical language came into use, was doubtless owing
to two circumstances. First, the very defective, vague, and barbarous
state of the old chemical nomenclature: for although, in consequence of
the prodigious progress which the science of chemistry has made since
the time of Lavoisier, his nomenclature is now nearly as inadequate
to express our ideas as that of Stahl was to express his; yet, at the
time of its appearance, its superiority over the old nomenclature was
so great, that it was immediately felt and acknowledged by all those
who were acquiring the science, who are the most likely to be free from
prejudices, and who, in the course of a few years, must constitute the
great body of those who are interested in the science. 2. The second
circumstance, to which the rapid triumph of the new nomenclature was
owing, is the superiority of Lavoisier's theory over that of Stahl.
The subsequent progress of the science has betrayed many weak points
in Lavoisier's opinions; yet its superiority over that of Stahl was
so obvious, and the mode of interrogating nature introduced by him
was so good, and so well calculated to advance the science, that no
unprejudiced person, who was at sufficient pains to examine both, could
hesitate about preferring that of Lavoisier. It was therefore generally
embraced by all the young chemists in every country; and they became,
at the same time, partial to the new nomenclature, by which only that
theory could be explained in an intelligible manner.

When the new nomenclature was published, there were only three nations
in Europe who could be considered as holding a distinguished place
as cultivators of chemistry: France, Germany, and Great Britain. For
Sweden had just lost her two great chemists, Bergman and Scheele, and
had been obliged, in consequence, to descend from the high chemical
rank which she had formerly occupied. In France the fashion, and of
course almost the whole nation, were on the side of the new chemistry.
Macquer, who had been a stanch phlogistian to the last, was just
dead. Monnet was closing his laborious career. Baumé continued to
adhere to the old opinions; but he was old, and his chemical skill,
which had never been _accurate_, was totally eclipsed by the more
elaborate researches of Lavoisier and his friends. Delametherie was
a keen phlogistian, a man of some abilities, of remarkable honesty
and integrity, and editor of the Journal de Physique, at that time a
popular and widely-circulating scientific journal. But his habits,
disposition, and conduct, were by no means suited to the taste of his
countrymen, or conformable to the practice of his contemporaries. The
consequence was, that he was shut out of all the scientific coteries
of Paris; and that his opinions, however strongly, or rather violently
expressed, failed to produce the intended effect. Indeed, as his
views were generally inaccurate, and expressed without any regard to
the rules of good manners, they in all probability rather served to
promote than to injure the cause of his opponents. Lavoisier and his
friends appear to have considered the subject in this light: they never
answered any of his attacks, or indeed took any notice of them. France,
then, from the date of the publication of the new nomenclature, might
be considered as enlisted on the side of the antiphlogistic theory.

The case was very different in Germany. The national prejudices of the
Germans were naturally enlisted on the side of Stahl, who was their
countryman, and whose reputation would be materially injured by the
refutation of his theory. The cause of phlogiston, accordingly, was
taken up by several German chemists, and supported with a good deal
of vigour; and a controversy was carried on for some years in Germany
between the old chemists who adhered to the doctrine of Stahl, and the
young chemists who had embraced the theory of Lavoisier. Gren, who was
at that time the editor of a chemical journal, deservedly held in high
estimation, and whose reputation as a chemist stood rather high in
Germany, finding it impossible to defend the Stahlian theory as it had
been originally laid down, introduced a new modification of phlogiston,
and attempted to maintain it against the antiphlogistians. The death
of Gren and of Wiegleb, who were the great champions of phlogiston,
left the field open to the antiphlogistians, who soon took possession
of all the universities and scientific journals in Germany. The most
eminent chemist in Germany, or perhaps in Europe at that time, was
Martin Henry Klaproth, professor of chemistry at Berlin, to whom
analytical chemistry lies under the greatest obligations. In the year
1792 he proposed to the Academy of Sciences of Berlin, of which he was
a member, to repeat all the requisite experiments before them, that
the members of the academy might be able to determine for themselves
which of the two theories deserved the preference. This proposal was
acceded to. All the fundamental experiments were repeated by Klaproth
with the most scrupulous attention to accuracy: the result was a
full conviction, on the part of Klaproth and the academy, that the
Lavoisierian theory was the true one. Thus the Berlin Academy became
antiphlogistians in 1792: and as Berlin has always been the focus of
chemistry in Germany, the determination of such a learned body must
have had a powerful effect in accelerating the propagation of the new
theory through that vast country.

In Great Britain the investigation of gaseous bodies, to which
the new doctrines were owing, had originated. Dr. Black had begun
the inquiry--Mr. Cavendish had prosecuted it with unparalleled
accuracy--and Dr. Priestley had made known a great number of new
gaseous bodies, which had hitherto escaped the attention of chemists.
As the British chemists had contributed more than those of any other
nation to the production of the new facts on which Lavoisier's theory
was founded, it was natural to expect that they would have embraced
that theory more readily than the chemists of any other nation: but
the matter of fact was somewhat different. Dr. Black, indeed, with
his characteristic candour, speedily embraced the opinions, and even
adopted the new nomenclature: but Mr. Cavendish new modelled the
phlogistic theory, and published a defence of phlogiston, which it was
impossible at that time to refute. The French chemists had the good
sense not to attempt to overturn it. Mr. Cavendish after this laid
aside the cultivation of chemistry altogether, and never acknowledged
himself a convert to the new doctrines.

Dr. Priestley continued a zealous advocate for phlogiston till the very
last, and published what he called a refutation of the antiphlogistic
theory about the beginning of the present century: but Dr. Priestley,
notwithstanding his merit as a discoverer and a man of genius, was
never, strictly speaking, entitled to the name of chemist; as he was
never able to make a chemical analysis. In his famous experiments, for
example, on the composition of water, he was obliged to procure the
assistance of Mr. Keir to determine the nature of the blue-coloured
liquid which he had obtained, and which Mr. Keir showed to be nitrate
of copper. Besides, Dr. Priestley, though perfectly honest and candid,
was so hasty in his decisions, and so apt to form his opinions without
duly considering the subject, that his chemical theories are almost all
erroneous and sometimes quite absurd.

Mr. Kirwan, who had acquired a high reputation, partly by his
_mineralogy_, and partly by his experiments on the composition of
the salts, undertook the task of refuting the antiphlogistic theory,
and with that view published a work to which he gave the name of "An
Essay on Phlogiston and the Composition of Acids." In that book he
maintained an opinion which seems to have been pretty generally adopted
by the most eminent chemists of the time; namely, that phlogiston is
the same thing with what is at present called _hydrogen_, and which,
when Kirwan wrote, was called light _inflammable air_. Of course Mr.
Kirwan undertook to prove that every combustible substance and every
metal contains hydrogen as a constituent, and that hydrogen escapes
in every case of combustion and calcination. On the other hand, when
calces are reduced to the metallic state hydrogen is absorbed. The book
was divided into thirteen sections. In the first the specific gravity
of the gases was stated according to the best data then existing. The
second section treats of the composition of acids, and the composition
and decomposition of water. The third section treats of sulphuric acid;
the fourth, of nitric acid; the fifth, of muriatic acid; the sixth,
of aqua regia; the seventh, of phosphoric acid; the eighth, of oxalic
acid; the ninth, of the calcination and reduction of metals and the
formation of fixed air; the tenth, of the dissolution of metals; the
eleventh, of the precipitation of metals by each other; the twelfth,
of the properties of iron and steel; while the thirteenth sums up the
whole argument by way of conclusion.

In this work Mr. Kirwan admitted the truth of M. Lavoisier's theory,
that during combustion and calcination, oxygen united with the burning
and calcining body. He admitted also that water is a compound of oxygen
and hydrogen. Now these admissions, which, however, it was scarcely
possible for a man of candour to refuse, rendered the whole of his
arguments in favour of the identity of hydrogen and phlogiston, and
of the existence of hydrogen in all combustible bodies, exceedingly
inconclusive. Kirwan's book was laid hold of by the French chemists,
as affording them an excellent opportunity of showing the superiority
of the new opinions over the old. Kirwan's view of the subject was
that which had been taken by Bergman and Scheele, and indeed by every
chemist of eminence who still adhered to the phlogistic system. A
satisfactory refutation of it, therefore, would be a death-blow to
phlogiston and would place the antiphlogistic theory upon a basis so
secure that it would be henceforth impossible to shake it.

Kirwan's work on phlogiston was accordingly translated into French,
and published in Paris. At the end of each section was placed an
examination and refutation of the argument contained in it by some one
of the French chemists, who had now associated themselves in order to
support the antiphlogistic theory. The introduction, together with the
second, third, and eleventh sections were examined and refuted by M.
Lavoisier; the fourth, the fifth, and sixth sections fell to the share
of M. Berthollet; the seventh and thirteenth sections were undertaken
by M. de Morveau; the eighth, ninth, and tenth, by M. De Fourcroy;
while the twelfth section, on iron and steel was animadverted on by
M. Monge. These refutations were conducted with so much urbanity of
manner, and were at the same time so complete, that they produced all
the effects expected from them. Mr. Kirwan, with a degree of candour
and liberality of which, unfortunately, very few examples can be
produced, renounced his old opinions, abandoned phlogiston, and adopted
the antiphlogistic doctrines of his opponents. But his advanced age,
and a different mode of experimenting from what he had been accustomed
to, induced him to withdraw himself entirely from experimental science
and to devote the evening of his life to metaphysical and logical and
moral investigations.

Thus, soon after the year 1790, a kind of interregnum took place in
British chemistry. Almost all the old British chemists had relinquished
the science, or been driven out of the field by the superior prowess
of their antagonists. Dr. Austin and Dr. Pearson will, perhaps, be
pointed out as exceptions. They undoubtedly contributed somewhat to
the progress of the science. But they were arranged on the side of
the antiphlogistians. Dr. Crawford, who had done so much for the
theory of heat, was about this time ruined in his circumstances by
the bankruptcy of a house to which he had intrusted his property.
This circumstance preyed upon a mind which had a natural tendency to
morbid sensibility, and induced this amiable and excellent man to put
an end to his existence. Dr. Higgins had acquired some celebrity as an
experimenter and teacher; but his disputes with Dr. Priestley, and his
laying claim to discoveries which certainly did not belong to him, had
injured his reputation, and led him to desert the field of science. Dr.
Black was an invalid, Mr. Cavendish had renounced the cultivation of
chemistry, and Dr. Priestley had been obliged to escape from the iron
hand of theological and political bigotry, by leaving the country. He
did little as an experimenter after he went to America; and, perhaps,
had he remained in England, his reputation would rather have diminished
than increased. He was an admirable pioneer, and as such, contributed
more than any one to the revolution which chemistry underwent; though
he was himself utterly unable to rear a permanent structure capable,
like the Newtonian theory, of withstanding all manner of attacks,
and becoming only the firmer and stronger the more it is examined.
Mr. Keir, of Birmingham, was a man of great eloquence, and possessed
of all the chemical knowledge which characterized the votaries of
phlogiston. In the year 1789 he attempted to stem the current of the
new opinions by publishing a dictionary of chemistry, in which all the
controversial points were to be fully discussed, and the antiphlogistic
theory examined and refuted. Of this dictionary only one part appeared,
constituting a very thin volume of two hundred and eight quarto pages,
and treating almost entirely of _acids_. Finding that the sale of
this work did not answer his expectations, and probably feeling, as
he proceeded, that the task of refuting the antiphlogistic opinions
was much more difficult, and much more hopeless than he expected, he
renounced the undertaking, and abandoned altogether the pursuit of
chemistry.

It will be proper in this place to introduce some account of the most
eminent of those French chemists who embraced the theory of Lavoisier,
and assisted him in establishing his opinions.

Claude-Louis Berthollet was born at Talloire, near Annecy, in Savoy,
on the 9th of December, 1748. He finished his school education at
Chambéry, and afterwards studied at the College of Turin, a celebrated
establishment, where many men of great scientific celebrity have been
educated. Here he attached himself to medicine, and after obtaining
a degree he repaired to Paris, which was destined to be the future
theatre of his speculations and pursuits.

In Paris he had not a single acquaintance, nor did he bring with him
a single introductory letter; but understanding that M. Tronchin,
at that time a distinguished medical practitioner in Paris, was a
native of Geneva, he thought he might consider him as in some measure
a countryman. On this slender ground he waited on M. Tronchin, and
what is rather surprising, and reflects great credit on both, this
acquaintance, begun in so uncommon a way, soon ripened into friendship.
Tronchin interested himself for his young _protégée_, and soon got him
into the situation of physician in ordinary to the Duke of Orleans,
father of him who cut so conspicuous a figure in the French revolution,
under the name of M. Egalité. In this situation he devoted himself to
the study of chemistry, and soon made himself known by his publications
on the subject.

In 1781 he was elected a member of the Academy of Sciences of Paris:
one of his competitors was M. Fourcroy. No doubt Berthollet owed his
election to the influence of the Duke of Orleans. In the year 1784 he
was again a competitor with M. de Fourcroy for the chemical chair at
the Jardin du Roi, left vacant by the death of Macquer. The chair was
in the gift of M. Buffon, whose vanity is said to have been piqued
because the Duke of Orleans, who supported Berthollet's interest, did
not pay him sufficient court. This induced him to give the chair to
Fourcroy; and the choice was a fortunate one, as his uncommon vivacity
and rapid elocution particularly fitted him for addressing a Parisian
audience. The chemistry-class at the Jardin du Roi immediately became
celebrated, and attracted immense crowds of admiring auditors.

But the influence of the Duke of Orleans was sufficient to procure
for Berthollet another situation which Macquer had held. This was
government commissary and superintendent of the dyeing processes.
It was this situation which naturally turned his attention to the
phenomena of dyeing, and occasioned afterwards his book on dyeing;
which at the time of its publication was excellent, and exhibited a
much better theory of dyeing, and a better account of the practical
part of the art than any work which had previously appeared. The arts
of dyeing and calico-printing have been very much improved since the
time that Berthollet's book was written; yet if we except Bancroft's
work on the permanent colours, nothing very important has been
published on the subject since that period. We are at present almost as
much in want of a good work on dyeing as we were when Berthollet's book
appeared.

In the year 1785 Berthollet, at a meeting of the Academy of Sciences,
informed that learned body that he had become a convert to the
antiphlogistic doctrines of Lavoisier. There was one point, however,
upon which he entertained a different opinion from Lavoisier, and
this difference of opinion continued to the last. Berthollet did not
consider oxygen as the acidifying principle. On the contrary, he was
of opinion that acids existed which contained no oxygen whatever.
As an example, he mentioned sulphuretted hydrogen, which possessed
the properties of an acid, reddening vegetable blues, and combining
with and neutralizing bases, and yet it was a compound of sulphur and
hydrogen, and contained no oxygen whatever. It is now admitted that
Berthollet was accurate in his opinion, and that oxygen is not of
itself an acidifying principle.

Berthollet continued in the uninterrupted prosecution of his studies,
and had raised himself a very high reputation when the French
revolution burst upon the world in all its magnificence. It is not
our business here to enter into any historical details, but merely
to remind the reader that all the great powers of Europe combined
to attack France, assisted by a formidable army of French emigrants
assembled at Coblentz. The Austrian and Prussian armies hemmed her
in by land, while the British fleets surrounded her by sea, and thus
shut her out from all communication with other nations. Thus France
was thrown at once upon her own resources. She had been in the habit
of importing her saltpetre, and her iron, and many other necessary
implements of war: these supplies were suddenly withdrawn; and it was
expected that France, thus deprived of all her resources, would be
obliged to submit to any terms imposed upon her by her adversaries.
At this time she summoned her men of science to her assistance, and
the call was speedily answered. Berthollet and Monge were particularly
active, and saved the French nation from destruction by their activity,
intelligence, and zeal. Berthollet traversed France from one extremity
to the other; pointed out the mode of extracting saltpetre from the
soil, and of purifying it. Saltpetre-works were instantly established
in every part of France, and gunpowder made of it in prodigious
quantity, and with incredible activity. Berthollet even attempted to
manufacture a new species of gunpowder still more powerful than the
old, by substituting chlorate of potash for saltpetre: but it was found
too formidable a substance to be made with safety.

The demand for cannon, muskets, sabres, &c., was equally urgent and
equally difficult to be supplied. A committee of men of science, of
which Berthollet and Monge were the leading members, was established,
and by them the mode of smelting iron, and of converting it into
steel, was instantly communicated, and numerous manufactories of these
indispensable articles rose like magic in every part of France.

This was the most important period of the life of Berthollet. It
was in all probability his zeal, activity, sagacity, and honesty,
which saved France from being overrun by foreign troops. But perhaps
the moral conduct of Berthollet was not less conspicuous than his
other qualities. During the reign of terror, a short time before the
9th Thermidor, when it was the system to raise up pretended plots,
to give pretexts for putting to death those that were obnoxious to
Robespierre and his friends, a hasty notice was given at a sitting
of the Committee of Public Safety, that a conspiracy had just been
discovered to destroy the soldiers, by poisoning the brandy which was
just going to be served out to them previous to an engagement. It was
said that the sick in the hospitals who had tasted this brandy, all
perished in consequence of it. Immediate orders were issued to arrest
those previously marked for execution. A quantity of the brandy was
sent to Berthollet to be examined. He was informed, at the same time,
that Robespierre wanted a conspiracy to be established, and all knew
that opposition to his will was certain destruction. Having finished
his analysis, Berthollet drew up his results in a Report, which he
accompanied with a written explanation of his views; and he there
stated, in the plainest language, that nothing poisonous was mixed
with the brandy, but that it had been diluted with water holding small
particles of slate in suspension, an ingredient which filtration would
remove. This report deranged the plans of the Committee of Public
Safety. They sent for the author, to convince him of the inaccuracy of
his analysis, and to persuade him to alter its results. Finding that
he remained unshaken in his opinion, Robespierre exclaimed, "What,
Sir! darest thou affirm that the muddy brandy is free from poison?"
Berthollet immediately filtered a glass of it in his presence, and
drank it off. "Thou art daring, Sir, to drink that liquor," exclaimed
the ferocious president of the committee. "I dared much more," replied
Berthollet, "when I signed my name to that Report." There can be no
doubt that he would have paid the penalty of this undaunted honesty
with his life, but that fortunately the Committee of Public Safety
could not at that time dispense with his services.

In the year 1792 Berthollet was named one of the commissioners of
the Mint, into the processes of which he introduced considerable
improvements. In 1794 he was appointed a member of the Commission
of Agriculture and the Arts: and in the course of the same year he
was chosen professor of chemistry at the Polytechnic School and
also in the Normal School. But his turn of mind did not fit him for
a public teacher. He expected too much information to be possessed
by his hearers, and did not, therefore, dwell sufficiently upon the
elementary details. His pupils were not able to follow his metaphysical
disquisitions on subjects totally new to them; hence, instead of
inspiring them with a love for chemistry, he filled them with langour
and disgust.

In 1795, at the organization of the Institute, which was intended to
include all men of talent or celebrity in France, we find Berthollet
taking a most active lead; and the records of the Institute afford
abundant evidence of the perseverance and assiduity with which he
laboured for its interests. Of the committees to which all original
memoirs are in the first place referred, we find Berthollet, oftener
than any other person, a member, and his signature to the report of
each work stands generally first.

In the year 1796, after the subjugation of Italy by Bonaparte,
Berthollet and Monge were selected by the Directory to proceed to
that country, in order to select those works of science and art with
which the Louvre was to be filled and adorned. While engaged in the
prosecution of that duty, they became acquainted with the victorious
general. He easily saw the importance of their friendship, and
therefore cultivated it with care; and was happy afterwards to possess
them, along with nearly a hundred other philosophers, as his companions
in his celebrated expedition to Egypt, expecting no doubt an eclat from
such a halo of surrounding science, as might favour the development of
his schemes of future greatness. On this expedition, which promised so
favourably for the French nation, and which was intended to inflict a
mortal stab upon the commercial greatness of Great Britain, Bonaparte
set out in the year 1798, accompanied by a crowd of the most eminent
men of science that France could boast of. That they might co-operate
more effectually in the cause of knowledge, these gentlemen formed
themselves into a society, named "The Institute of Egypt," which was
constituted on the same plan as the National Institute of France. Their
first meeting was on the 6th Fructidor (24th of August), 1798; and
after that they continued to assemble, at stated intervals. At these
meetings papers were read, by the respective members, on the climate,
the inhabitants, and the natural and artificial productions of the
country to which they had gone. These memoirs were published in 1800,
in Paris, in a single volume entitled, "Memoirs of the Institute of
Egypt."

The history of the Institute of Egypt, as related by Cuvier, is not
a little singular, and deserves to be stated. Bonaparte, during
his occasional intercourse with Berthollet in Italy, was delighted
with the simplicity of his manners, joined to a force and depth of
thinking which he soon perceived to characterize our chemist. When
he returned to Paris, where he enjoyed some months of comparative
leisure, he resolved to employ his spare time in studying chemistry
under Berthollet. It was at this period that his illustrious pupil
imparted to our philosopher his intended expedition to Egypt, of which
no whisper was to be spread abroad till the blow was ready to fall;
and he begged of him not merely to accompany the army himself, but to
choose such men of talent and experience as he conceived fitted to
find there an employment worthy of the country which they visited,
and of that which sent them forth. To invite men to a hazardous
expedition, the nature and destination of which he was not permitted
to disclose, was rather a delicate task; yet Berthollet undertook it.
He could simply inform them that he would himself accompany them;
yet such was the universal esteem in which he was held, such was the
confidence universally placed in his honesty and integrity, that all
the men of science agreed at once, and without hesitation, to embark
on an unknown expedition, the dangers of which he was to share along
with them. Had it not been for the link which Berthollet supplied
between the commander-in-chief and the men of science, it would have
been impossible to have united, as was done on this occasion, the
advancement of knowledge with the progress of the French arms.

During the whole of this expedition, Berthollet and Monge distinguished
themselves by their firm friendship, and by their mutually braving
every danger to which any of the common soldiers could be exposed.
Indeed, so intimate was their association that many of the army
conceived Berthollet and Monge to be one individual; and it is no small
proof of the intimacy of these philosophers with Bonaparte, that the
soldiers had a dislike at this double personage, from a persuasion
that it had been at his suggestion that they were led into a country
which they detested. It happened on one occasion that a boat, in which
Berthollet and some others were conveyed up the Nile, was assailed by a
troop of Mamelukes, who poured their small shot into it from the banks.
In the midst of this perilous voyage, M. Berthollet began very coolly
to pick up stones and stuff his pockets with them. When his motive for
this conduct was asked, "I am desirous," said he, "that in case of my
being shot, my body may sink at once to the bottom of this river, and
may escape the insults of these barbarians."

In a conjuncture where a courage of a rarer kind was required,
Berthollet was not found wanting. The plague broke out in the French
army, and this, added to the many fatigues they had previously endured,
the diseases under which they were already labouring, would, it was
feared, lead to insurrection on the one hand, or totally sink the
spirits of the men on the other. Acre had been besieged for many weeks
in vain. Bonaparte and his army had been able to accomplish nothing
against it: he was anxious to conceal from his army this disastrous
intelligence. When the opinion of Berthollet was asked in council,
he spoke at once the plain, though unwelcome truth. He was instantly
assailed by the most violent reproaches. "In a week," said he, "my
opinion will be unfortunately but too well vindicated." It was as he
foretold: and when nothing but a hasty retreat could save the wretched
remains of the army of Egypt, the carriage of Berthollet was seized
for the convenience of some wounded officers. On this, he travelled on
foot, and without the smallest discomposure, across twenty leagues of
the desert.

When Napoleon abandoned the army of Egypt, and traversed half the
Mediterranean in a single vessel, Berthollet was his companion.
After he had put himself at the head of the French government, and
had acquired an extent of power, which no modern European potentate
had ever before realized, he never forgot his associate. He was in
the habit of placing all chemical discoveries to his account, to the
frequent annoyance of our chemist; and when an unsatisfactory answer
was given him upon any scientific subject, he was in the habit of
saying, "Well; I shall ask this of Berthollet." But he did not limit
his affection to these proofs of regard. Having been informed that
Berthollet's earnest pursuits of science had led him into expenses
which had considerably deranged his fortune, he sent for him, and said,
in a tone of affectionate reproach, "M. Berthollet, I have always one
hundred thousand crowns at the service of my friends." And, in fact,
this sum was immediately presented to him.

Upon his return from Egypt, Berthollet was nominated a senator by the
first consul; and afterwards received the distinction of grand officer
of the Legion of Honour; grand cross of the Order of Reunion; titulary
of the Senatory of Montpellier; and, under the emperor, he was created
a peer of France, receiving the title of Count. The advancement to
these offices produced no change in the manners of Berthollet. Of this
he gave a striking proof, by adopting, as his armorial bearing (at the
time that others eagerly blazoned some exploit), the plain unadorned
figure of his faithful and affectionate dog. He was no courtier
before he received these honours, and he remained equally simple and
unassuming, and not less devoted to science after they were conferred.

As we advance towards the latter period of his life, we find the same
ardent zeal in the cause of science which had glowed in his early
youth, accompanied by the same generous warmth of heart that he ever
possessed, and which displayed itself in his many intimate friendships
still subsisting, though mellowed by the hand of time. At this period
La Place lived at Arcueil, a small village about three miles from
Paris. Between him and Berthollet there had long subsisted a warm
affection, founded on mutual esteem. To be near this illustrious
man Berthollet purchased a country-seat in the village: there he
established a very complete laboratory, fit for conducting all kinds of
experiments in every branch of natural philosophy. Here he collected
round him a number of distinguished young men, who knew that in his
house their ardour would at once receive fresh impulse and direction
from the example of Berthollet. These youthful philosophers were
organized by him into a society, to which the name of Société d'Arcueil
was given. M. Berthollet was himself the president, and the other
members were La Place, Biot, Gay-Lussac, Thenard, Collet-Descotils,
Decandolle, Humboldt, and A. B. Berthollet. This society published
three volumes of very valuable memoirs. The energy of this society was
unfortunately paralyzed by an untoward event, which imbittered the
latter days of this amiable man. His only son, M. A. B. Berthollet, in
whom his happiness was wrapped up, was unfortunately afflicted with a
lowness of spirits which rendered his life wholly insupportable to him.
Retiring to a small room, he locked the door, closed up every chink
and crevice which might admit the air, carried writing materials to
a table, on which he placed a second-watch, and then seated himself
before it. He now marked precisely the hour, and lighted a brasier of
charcoal beside him. He continued to note down the series of sensations
he then experienced in succession, detailing the approach and rapid
progress of delirium; until, as time went on, the writing became
confused and illegible, and the young victim dropped dead upon the
floor.

After this event the spirits of the old man never again rose.
Occasionally some discovery, extending the limits of his favourite
science, engrossed his interest and attention for a short time: but
such intervals were rare, and shortlived. The restoration of the
Bourbons, and the downfall of his friend and patron Napoleon, added to
his sufferings by diminishing his income, and reducing him from a state
of affluence to comparative embarrassment. But he was now old, and the
end of his life was approaching. In 1822 he was attacked by a slight
fever, which left behind it a number of boils: these were soon followed
by a gangrenous ulcer of uncommon size. Under this he suffered for
several months with surprising fortitude. He himself, as a physician,
knew the extent of his danger, felt the inevitable progress of the
malady, and calmly regarded the slow approach of death. At length,
after a tedious period of suffering, in which his equanimity had never
once been shaken, he died on the 6th of November, when he had nearly
completed the seventy-fourth year of his age.

His papers are exceedingly numerous, and of a very miscellaneous
nature, amounting to more than eighty. The earlier were chiefly
inserted into the various volumes of the Memoirs of the Academy.
He furnished many papers to the Annales de Chimie and the Journal
de Physique, and was also a frequent contributor to the Society of
Arcueil, in the different volumes of whose transactions several memoirs
of his are to be found. He was the author likewise of two separate
works, comprising each two octavo volumes. These were his Elements of
the Art of Dyeing, first published in 1791, in a single volume: but the
new and enlarged edition of 1814 was in two volumes; and his Essay on
Chemical Statics, published about the beginning of the present century.
I shall notice his most important papers.

His earlier memoirs on sulphurous acid, on volatile alkali, and on
the decomposition of nitre, were encumbered by the phlogistic theory,
which at that time he defended with great zeal, though he afterwards
retracted these his first opinions upon all these subjects. Except his
paper on soaps, in which he shows that they are chemical compounds
of an oil (acting the part of an acid) and an alkaline base, and his
proof that phosphoric acid exists ready formed in the body (a fact long
before demonstrated by Gahn and Scheele), his papers published before
he became an antiphlogistian are of inferior merit.

In 1785 he demonstrated the nature and proportion of the constituents
of ammonia, or volatile alkali. This substance had been collected in
the gaseous form by the indefatigable Priestley, who had shown also
that when electric sparks are made to pass for some time through a
given volume of this gas, its bulk is nearly doubled. Berthollet merely
repeated this experiment of Priestley, and analyzed the new gases
evolved by the action of electricity. This gas he found a mixture of
three volumes hydrogen and one volume azotic gas: hence it was evident
that ammoniacal gas is a compound of three volumes of hydrogen and one
volume of azotic gas united together, and condensed into two volumes.
The same discovery was made about the same time by Dr. Austin, and
published in the Philosophical Transactions. Both sets of experiments
were made without any knowledge of what was done by the other: but it
is admitted, on all hands, that Berthollet had the priority in point of
time.

It was about this time, likewise, that he published his first paper on
chlorine. He observed, that when water, impregnated with chlorine, is
exposed to the light of the sun, the water loses its colour, while, at
the same time, a quantity of oxygen gas is given out. If we now examine
the water, we find that it contains no chlorine, but merely a little
muriatic acid. This fact, which is undoubted, led him to conclude
that chlorine is decomposed by the action of solar light, and that its
two elements are muriatic acid and oxygen. This led to the notion that
the basis of muriatic acid is capable of combining with various doses
of oxygen, and of forming various acids, one of which is chlorine: on
that account it was called _oxygenized muriatic acid_ by the French
chemists, which unwieldy appellation was afterwards shortened by Kirwan
into _oxymuriatic acid_.

Berthollet observed that when a current of chlorine gas is passed
through a solution of carbonate of potash an effervescence takes place
owing to the disengagement of carbonic acid gas. By-and-by crystals
are deposited in fine silky scales, which possess the property of
detonating with combustible bodies still more violently than saltpetre.
Berthollet examined these crystals and showed that they were compounds
of potash with an acid containing much more oxygen than oxymuriatic
acid. He considered its basis as muriatic acid, and distinguished it by
the name of hyper-oxymuriatic acid.

It was not till the year 1810, that the inaccuracy of these opinions
was established. Gay-Lussac and Thenard attempted in vain to
extract oxygen from chlorine. They showed that not a trace of that
principle could be detected. Next year Davy took up the subject and
concluded from his experiments that _chlorine_ is a simple substance,
that muriatic acid is a compound of chlorine and hydrogen, and
hyper-oxymuriatic acid of chlorine and oxygen. Gay-Lussac obtained this
acid in a separate state, and gave it the name of _chloric acid_, by
which it is now known.

Scheele, in his original experiments on chlorine, had noticed the
property which it has of destroying vegetable colours. Berthollet
examined this property with care, and found it so remarkable that
he proposed it as a substitute for exposure to the sun in bleaching.
This suggestion alone would have immortalized Berthollet had he done
nothing else; since its effect upon some of the most important of
the manufactures of Great Britain has been scarcely inferior to that
of the steam-engine itself. Mr. Watt happened to be in Paris when
the idea suggested itself to Berthollet. He not only communicated it
to Mr. Watt, but showed him the process in all its simplicity. It
consisted in nothing else than in steeping the cloth to be bleached
in water impregnated with chlorine gas. Mr. Watt, on his return to
Great Britain, prepared a quantity of this liquor, and sent it to his
father-in-law, Mr. Macgregor, who was a bleacher in the neighbourhood
of Glasgow. He employed it successfully, and thus was the first
individual who tried the new process of bleaching in Great Britain. For
a number of years the bleachers in Lancashire and the neighbourhood
of Glasgow were occupied in bringing the process to perfection. The
disagreeable smell of the chlorine was a great annoyance. This was
attempted to be got rid of by dissolving potash in the water to be
impregnated with chlorine; but it was found to injure considerably the
bleaching powers of the gas. The next method tried was to mix the water
with quicklime, and then to pass a current of chlorine through it. The
quicklime was dissolved, and the liquor thus constituted was found to
answer very well. The last improvement was to combine the chlorine
with dry lime. At first two atoms of lime were united to one atom of
chlorine; but of late years it is a compound of one atom of lime, and
one of chlorine. This chloride is simply dissolved in water, and the
cloth to be bleached is steeped in it. For all these improvements,
which have brought the method of bleaching by means of chlorine to
great simplicity and perfection, the bleachers are indebted to Knox,
Tennant, and Mackintosh, of Glasgow; by whose indefatigable exertions
the mode of manufacturing chloride of lime has been brought to a state
of perfection.

Berthollet's experiments on prussic acid and the prussiates deserve
also to be mentioned, as having a tendency to rectify some of the ideas
at that time entertained by chemists, and to advance their knowledge
of one of the most difficult departments of chemical investigation.
In consequence of his experiments on the nature and constituents of
sulphuretted hydrogen, he had already concluded that it was an acid,
and that it was destitute of oxygen: this had induced him to refuse his
assent to the hypothesis of Lavoisier, that _oxygen_ is the _acidifying
principle_. Scheele, in his celebrated experiments on prussic acid,
had succeeded in ascertaining that its constituents were carbon and
azote; but he had not been able to make a rigid analysis of that
acid, and consequently to demonstrate that oxygen did not enter into
it as a constituent. Berthollet took up the subject, and though his
analysis was also incomplete, he satisfied himself, and rendered it
exceedingly probable, that the only constituents of this acid were,
carbon, azote, and hydrogen, and that oxygen did not enter into it as
a constituent. This was another reason for rejecting the notion of
_oxygen_ as an acidifying principle. Here were two acids capable of
neutralizing bases, namely, sulphuretted hydrogen and prussic acid, and
yet neither of them contained oxygen. He found that when prussic acid
was treated with chlorine, its properties were altered; it acquired a
different smell and taste, and no longer precipitated iron blue, but
green. From his opinion respecting the nature of chlorine, that it was
a compound of muriatic acid and oxygen, he naturally concluded that by
this process he had formed a new prussic acid by adding oxygen to the
old constituents. He therefore called this new substance _oxyprussic
acid_. It has been proved by the more recent experiments of Gay-Lussac,
that the new acid of Berthollet is a compound of _cyanogen_ (the
prussic acid deprived of hydrogen) and _chlorine_: it is now called
_chloro-cyanic acid_, and is known to possess the characters assigned
it by Berthollet: it constitutes, therefore, a new example of an acid
destitute of oxygen. Berthollet was the first person who obtained
prussiate of potash in regular crystals; the salt was known long
before, but had been always used in a state of solution.

Berthollet's discovery of fulminating silver, and his method of
obtaining pure hydrated potash and soda, by means of alcohol, deserve
to be mentioned. This last process was of considerable importance to
analytical chemistry. Before he published his process, these substances
in a state of purity were not known.

I think it unnecessary to enter into any details respecting his
experiments on sulphuretted hydrogen, and the hydrosulphurets and
sulphurets. They contributed essentially to elucidate that obscure part
of chemistry. But his success was not perfect; nor did we understand
completely the nature of these compounds, till the nature of the
alkaline bases had been explained by the discoveries of Davy.

The only other work of Berthollet, which I think it necessary to notice
here, is his book entitled "Chemical Statics," which he published
in 1803. He had previously drawn up some interesting papers on the
subject, which were published in the Memoirs of the Institute. Though
chemical affinity constitutes confessedly the basis of the science,
it had been almost completely overlooked by Lavoisier, who had done
nothing more on the subject than drawn up some tables of affinity,
founded on very imperfect data. Morveau had attempted a more profound
investigation of the subject in the article _Affinité_, inserted in
the chemical part of the Encyclopédie Méthodique. His object was, in
imitation of Buffon, who had preceded him in the same investigation,
to prove that chemical affinity is merely a case of the _attraction of
gravitation_. But it is beyond our reach, in the present state of our
knowledge, to determine the amount of attraction which the atoms of
bodies exert with respect to each other. This was seen by Newton, and
also by Bergman, who satisfied themselves with considering it as an
attraction, without attempting to determine its amount; though Newton,
with his usual sagacity, was inclined, from the phenomena of light,
to consider the attraction of affinity as much stronger than that
of gravitation, or at least as increasing much more rapidly, as the
distances between the attracting particles diminished.

Bergman, who had paid great attention to the subject, considered
affinity as a certain determinate attraction, which the atoms of
different bodies exerted towards each other. This attraction varies
in intensity between every two bodies, though it is constant between
each pair. The consequence is, that these intensities may be denoted by
numbers. Thus, suppose a body _m_, and the atoms of six other bodies,
_a_, _b_, _c_, _d_, _e_, _f_, to have an affinity for _m_, the forces
by which they are attracted towards each other may be represented by
the numbers x, x+1, x+2, x+3, x+4, x+5. And the attractions may be
represented thus:

  Attraction between _m_ & _a_ = x
                     _m_ & _b_ = x+1
                     _m_ & _c_ = x+2
                     _m_ & _d_ = x+3
                     _m_ & _e_ = x+4
                     _m_ & _f_ = x+5

Suppose we have the compound _m a_, if we present _b_, it will unite
with _m_ and displace _a_, because the attraction between _m_ and _a_
is only x, while that between _m_ & _b_ is x+1: _c_ will displace _b_;
_d_ will displace _c_, and so on, for the same reason. On this account
Bergman considered affinity as an _elective attraction_, and in his
opinion the intensity may always be estimated by decomposition. That
substance which displaces another from a third, has a greater affinity
than the body which is displaced. If _b_ displace _a_ from the compound
_a m_, then _b_ has a greater affinity for _m_ than _a_ has.

The object of Berthollet in his Chemical Statics, was to combat this
opinion of Bergman, which had been embraced without examination
by chemists in general. If affinity be an attraction, Berthollet
considered it as evident that it never could occasion decomposition.
Suppose _a_ to have an affinity for _m_, and _b_ to have an affinity
for the same substances. Let the affinity between _b_ and _m_ be
greater than that between _a m_. Let _b_ be mixed with a solution of
the compound _a m_, then in that case _b_ would unite with _a m_,
and form the triple compound _a m b_. Both _a_ and _b_ would at once
unite with _m_. No reason can be assigned why _a_ should separate from
_m_, and _b_ take its place. Berthollet admitted that in fact such
decompositions often happened; but he accounted for them from other
causes, and not from the superior affinity of one body over another.
Suppose we have a solution of _sulphate of soda_ in water. This salt is
a compound of _sulphuric acid_ and _soda_; two substances between which
a strong affinity subsists, and which therefore always unites whenever
they come in contact. Suppose we have dissolved in another portion
of water, a quantity of barytes, just sufficient to saturate the
sulphuric acid in the sulphate of soda. If we mix these two solutions
together. The barytes will combine with the sulphuric acid and the
compound (_sulphate of barytes_) will fall to the bottom, leaving a
pure solution of soda in the water. In this case the barytes has seized
all the sulphuric acid, and displaced the soda. The reason of this,
according to Berthollet, is not that barytes has a stronger affinity
for sulphuric acid than soda has; but because sulphate of barytes
is insoluble in water. It therefore falls down, and of course the
sulphuric acid is withdrawn from the soda. But if we add to a solution
of sulphate of soda as much potash as will saturate all the sulphuric
acid, no such decomposition will take place; at least, we have no
evidence that it does. Both the alkalies, in this case, will unite to
the acid and form a triple compound, consisting of potash, sulphuric
acid, and soda. Let us now concentrate the solution by evaporation,
and crystals of sulphate of potash will fall down. The reason is, that
sulphate of potash is not nearly so soluble in water as sulphate of
soda. Hence it separates; not because sulphuric acid has a greater
affinity for potash than for soda, but because sulphate of potash is a
much less soluble salt than sulphate of soda.

This mode of reasoning of Berthollet is plausible, but not convincing:
it is merely an _argumentum ad ignorantiam_. We can only prove the
decomposition by separating the salts from each other, and this can
only be done by their difference of solubility. But cases occur in
which we can judge that decomposition has taken place from some other
phenomena than precipitation. For example, _nitrate of copper_ is a
_blue_ salt, while _muriate of copper_ is _green_. If into a solution
of nitrate of copper we pour muriatic acid, no precipitation appears,
but the colour changes from blue to green. Is not this an evidence that
the muriatic acid has displaced the nitric, and that the salt held in
solution is not nitrate of copper, as it was at first, but muriate of
copper?

Berthollet accounts for all decompositions which take place when a
third body is added, either by insolubility or by _elasticity_: as, for
example, when sulphuric acid is poured into a solution of carbonate
of ammonia, the carbonic acid all flies off, in consequence of its
elasticity, and the sulphuric acid combines with the ammonia in its
place. I confess that this explanation, of the reason why the carbonic
acid flies off, appears to me very defective. The ammonia and carbonic
acid are united by a force quite sufficient to overcome the elasticity
of the carbonic acid. Accordingly, it exhibits no tendency to escape.
Now, why should the elasticity of the acid cause it to escape when
sulphuric acid is added? It certainly could not do so, unless it has
weakened the affinity by which it is kept united to the ammonia. Now
this is the very point for which Bergman contends. The subject will
claim our attention afterwards, when we come to the electro-chemical
discoveries, which distinguished the first ten years of the present
century.

Another opinion supported by Berthollet in his Chemical Statics is,
that quantity may be made to overcome force; or, in other words, that
it we mix a great quantity of a substance which has a weaker affinity
with a small quantity of a substance which has a stronger affinity, the
body having the weaker affinity will be able to overcome the other, and
combine with a third body in place of it. He gave a number of instances
of this; particularly, he showed that a large quantity of potash,
when mixed with a small quantity of sulphate of barytes, is able to
deprive the barytes of a portion of its sulphuric acid. In this way he
accounted for the decomposition of the common salt, by carbonate of
lime in the soda lakes in Egypt; and the decomposition of the same
salt by iron, as noticed by Scheele.

I must acknowledge myself not quite satisfied with Berthollet's
reasoning on this subject. No doubt if two atoms of a body having a
weaker affinity, and one atom of a body having a stronger affinity,
were placed at equal distances from an atom of a third body, the
force of the two atoms might overcome that of the one atom. And it is
possible that such cases may occasionally occur: but such a balance
of distances must be rare and accidental. I cannot but think that all
the cases adduced by Berthollet are of a complicated nature, and admit
of an explanation independent of the efficacy of mass. And at any
rate, abundance of instances might be stated, in which mass appears to
have no preponderating effect whatever. Chemical decomposition is a
phenomenon of so complicated a nature, that it is more than doubtful
whether we are yet in possession of data sufficient to enable us to
analyze the process with accuracy.

Another opinion brought forward by Berthollet in his work was of a
startling nature, and occasioned a controversy between him and Proust
which was carried on for some years with great spirit, but with perfect
decorum and good manners on both sides. Berthollet affirmed that bodies
were capable of uniting with each other in all possible proportions,
and that there is no such thing as a definite compound, unless it
has been produced by some accidental circumstances, as insolubility,
volatility, &c. Thus every metal is capable of uniting with all
possible doses of oxygen. So that instead of one or two oxides of
every metal, an infinite number of oxides of each metal exist. Proust
affirmed that all compounds are definite. Iron, says he, unites with
oxygen only in two proportions; we have either a compound of 3·5 iron
and 1 oxygen, or of 3·5 iron and 1·5 oxygen. The first constitutes
the _black_, and the second the _red_ oxide of iron; and beside these
there is no other. Every one is now satisfied that Proust's view of
the subject was correct, and Berthollet's erroneous. But a better
opportunity will occur hereafter to explain this subject, or at least
to give the information respecting it which we at present possess.

Berthollet in this book points out the quantity of each base necessary
to neutralize a given weight of acid, and he considers the strength
of affinity as inversely that quantity. Now of all the bases known
when Berthollet wrote, ammonia is capable of saturating the greatest
quantity of acid. Hence he considered its affinity for acids as
stronger than that of any other base. Barytes, on the contrary,
saturates the smallest quantity of acid; therefore its affinity for
acids is smallest. Now ammonia is separated from acids by all the
other bases; while there is not one capable of separating barytes. It
is surprising that the notoriety of this fact did not induce him to
hesitate, before he came to so problematical a conclusion. Mr. Kirwan
had already considered the force of affinity as directly proportional
to the quantity of base necessary to saturate a given weight of acid.
When we consider the subject metaphysically, Berthollet's opinion is
most plausible; for it is surely natural to consider that body as the
strongest which produces the greatest effect. Now when we deprive an
acid of its properties, or neutralize it by adding a base, one would
be disposed to consider that base as acting with most energy, which
with the smallest quantity of matter is capable of producing a given
effect. This was the way that Berthollet reasoned. But if we attend
to the power which one base has of displacing another, we shall find
it very nearly proportional to the weight of it necessary to saturate
a given weight of acid; or, at least those bases act most powerfully
in displacing others of which the greatest quantity is necessary to
saturate a given weight of acid. Kirwan's opinion, therefore, was more
conformable to the order of decomposition. These two opposite views of
the subject show clearly that neither Kirwan nor Berthollet had the
smallest conception of the atomic theory; and, consequently, that the
allegation of Mr. Higgens, that he had explained the atomic theory
in his book on phlogiston, published in the year 1789, was not well
founded. Whether Berthollet had read that book I do not know, but there
can be no doubt that it was perused by Kirwan; who, however, did not
receive from it the smallest notions respecting the atomic theory. Had
he imbibed any such notions, he never would have considered chemical
affinity as capable of being measured by the weight of base capable of
neutralizing a given weight of acid.

Berthollet was not only a man of great energy of character, but of
the most liberal feelings and benevolence. The only exception to this
is his treatment of M. Clement. This gentleman, in company with M.
Desormes, had examined the carbonic oxide of Priestley, and had shown
as Cruikshanks had done before them, that it is a compound of carbon
and oxygen, and that it contains no hydrogen whatever. Berthollet
examined the same gas, and he published a paper to prove that it was
a triple compound of oxygen, carbon, and hydrogen. This occasioned a
controversy, which chemists have finally determined in favour of the
opinion of Clement and Desormes. Berthollet, during this discussion,
did not on every occasion treat his opponents with his accustomed
temper and liberality; and ever after he opposed all attempts on the
part of Clement to be admitted a member of the Institute. Whether
there was any other reason for this conduct on the part of Berthollet,
besides difference of opinion respecting the composition of carbonic
oxide, I do not know: nor would it be right to condemn him without a
more exact knowledge of all the circumstances than I can pretend to.

Antoine François de Fourcroy, was born at Paris on the 15th of June,
1755. His family had long resided in the capital, and several of his
ancestors had distinguished themselves at the bar. But the branch from
which he sprung had gradually sunk into poverty. His father exercised
in Paris the trade of an apothecary, in consequence of a charge
which he held in the house of the Duke of Orleans. The corporation
of apothecaries having obtained the general suppression of all such
charges, M. de Fourcroy, the father, was obliged to renounce his mode
of livelihood; and his son grew up in the midst of the poverty produced
by the monopoly of the privileged bodies in Paris. He felt this
situation the more keenly, because he possessed from nature an extreme
sensibility of temper. When he lost his mother, at the age of seven
years, he attempted to throw himself into her grave. The care of an
elder sister preserved him with difficulty till he reached the age at
which it was usual to be sent to college. There he was unlucky enough
to meet with a brutal master, who conceived an aversion for him and
treated him with cruelty: the consequence, was, a dislike to study; and
he quitted the college at the age of fourteen, somewhat less informed
than when he went to it.

His poverty now was such that he was obliged to endeavour to support
himself by becoming writing-master. He had even some thoughts of going
on the stage; but was prevented by the hisses bestowed on a friend
of his who had unadvisedly entered upon that perilous career, and was
treated in consequence without mercy by the audience. While uncertain
what plan to follow, the advice of Viq. d'Azyr induced him to commence
the study of medicine.

This great anatomist was an acquaintance of M. de Fourcroy, the father.
Struck with the appearance of his son, and the courage with which he
struggled with his bad fortune, he conceived an affection for him, and
promised to direct his studies, and even to assist him during their
progress. The study of medicine to a man in his situation was by no
means an easy task. He was obliged to lodge in a garret, so low in
the roof that he could only stand upright in the middle of the room.
Beside him lodged a water-carrier with twelve children. Fourcroy acted
as physician to this numerous family, and in recompence was always
supplied with abundance of water. He contrived to support himself by
giving lessons to other students, by facilitating the researches of
richer writers, and by some translations which he sold to a bookseller.
For these he was only half paid; but the conscientious bookseller
offered thirty years afterwards to make up the deficiency, when his
creditor was become director-general of public instruction.

Fourcroy studied with so much zeal and ardour that he soon became well
acquainted with the subject of medicine. But this was not sufficient.
It was necessary to get a doctor's degree, and all the expenses at that
time amounted to 250_l._ An old physician, Dr. Diest, had left funds
to the faculty to give a gratuitous degree and licence, once every two
years, to the poor student who should best deserve them. Fourcroy was
the most conspicuous student at that time in Paris. He would therefore
have reaped the benefit of this benevolent institution had it not
been for the unlucky situation in which he was placed. There happened
to exist a quarrel between the faculty charged with the education of
medical men and the granting of degrees, and a society recently formed
by government for the improvement of the medical art. This dispute had
been carried to a great length, and had attracted the attention of all
the frivolous and idle inhabitants of Paris. Viq. d'Azyr was secretary
to the society, and of course one of its most active champions; and
was, in consequence, particularly obnoxious to the faculty of medicine
at Paris. Fourcroy was unluckily the acknowledged _protégée_ of this
eminent anatomist. This was sufficient to induce the faculty of
medicine to refuse him a gratuitous degree. He would have been excluded
in consequence of this from entering on the career of a practitioner,
had not the society, enraged at this treatment, and influenced by
a violent party spirit, formed a subscription, and contributed the
necessary expenses.

It was no longer possible to refuse M. de Fourcroy the degree of
doctor, when he was thus enabled to pay for it. But above the simple
degree of doctor there was another, entitled _docteur regent_, which
depended entirely on the votes of the faculty. It was unanimously
refused to M. de Fourcroy. This refusal put it out of his power
afterwards to commence teacher in the medical school, and gave the
medical faculty the melancholy satisfaction of not being able to enroll
among their number the most celebrated professor in Paris. This violent
and unjust conduct of the faculty of medicine made a deep impression on
the mind of Fourcroy, and contributed not a little to the subsequent
downfall of that powerful body.

Fourcroy being thus entitled to practise in Paris, his success depended
entirely on the reputation which he could contrive to establish.
For this purpose he devoted himself to the sciences connected with
medicine, as the shortest and most certain road by which he could
reach his object. His first writings showed no predilection for any
particular branch of science. He wrote upon _chemistry_, _anatomy_,
and _natural history_. He published an Abridgment of the History of
Insects, and a Description of the Bursæ Mucosæ of the Tendons. This
last piece seems to have given him the greatest celebrity; for in
1785 he was admitted, in consequence of it, into the academy as an
anatomist. But the reputation of Bucquet, at that time very high,
gradually drew his particular attention to chemistry, and he retained
this predilection during the rest of his life.

Bucquet was at that time professor of chemistry in the Medical School
of Paris, and was greatly celebrated and followed on account of his
eloquence, and the elegance of his language. Fourcroy became in the
first place his pupil, and afterwards his particular friend. One
day, when a sudden attack of disease prevented him from lecturing as
usual, he entreated Fourcroy to supply his place. Our young chemist at
first declined, and alleged his ignorance of the method of addressing
a public audience. But, overcome by the persuasions of Bucquet,
he at last consented: and in this, his first essay, he spoke two
hours without disorder or hesitation, and acquitted himself to the
satisfaction of his whole audience. Bucquet soon after substituted him
in his place, and it was in his laboratory and in his class-room that
he first made himself acquainted with chemistry. He was enabled at the
death of Bucquet, in consequence of an advantageous marriage that he
had made, to purchase the apparatus and cabinet of his master; and
although the faculty of medicine would not allow him to succeed to the
chair of Bucquet, they could not prevent him from succeeding to his
reputation.

There was a kind of college which had been established in the Jardin
du Roi, which at that time was under the superintendence of Buffon,
and Macquer was the professor of chemistry in this institution. On
the death of this chemist, in 1784, both Berthollet and Fourcroy
offered themselves as candidates for the vacant chair. The voice of
the public was so loud in favour of Fourcroy, that he was appointed
to the situation in spite of the high character of his antagonist and
the political influence which was exerted in his favour. He filled
this chair for twenty-five years, with a reputation for eloquence
continually on the increase. Such were the crowds, both of men and
women, who flocked to hear him, that it was twice necessary to enlarge
the size of the lecture room.

After the revolution had made some progress, he was named a member of
the National Convention in the autumn of the memorable year 1793. It
was during the reign of terror, when the Convention itself, and with
it all France, was under the absolute dominion of one of the most
sanguinary monsters that ever existed: it was almost equally dangerous
for the members of the Convention to remain silent, or to take an
active part in the business of that assembly. Fourcroy never opened his
mouth in the Convention till after the death of Robespierre; at this
period he had influence enough to save the lives of some men of merit:
among others, of Darcet, who did not know the obligation under which he
lay to him till long after; at last his own life was threatened, and
his influence, of course, completely annihilated.

It was during this unfortunate and disgraceful period, that many
eminent men lost their lives; among others, Lavoisier; and Fourcroy is
accused of having contributed to the death of this illustrious chemist:
but Cuvier entirely acquits him of this atrocious charge, and assures
us that it was urged against him merely out of envy at his subsequent
elevation. "If in the rigorous researches which we have made," says
Cuvier in his Eloge of Fourcroy, "we had found the smallest proof of
an atrocity so horrible, no human power could have induced us to sully
our mouths with his Eloge, or to have pronounced it within the walls of
this temple, which ought to be no less sacred to honour than to genius."

Fourcroy began to acquire influence only after the 9th Thermidor, when
the nation was wearied with destruction, and when efforts were making
to restore those monuments of science, and those public institutions
for education, which during the wantonness and folly of the revolution
had been overturned and destroyed. Fourcroy was particularly active
in this renovation, and it was to him, chiefly, that the schools
established in France for the education of youth are to be ascribed.
The Convention had destroyed all the colleges, universities, and
academies throughout France. The effects of this absurd abolition soon
became visible; the army stood in need of surgeons and physicians, and
there were none educated to supply the vacant places: three new schools
were founded for educating medical men; they were nobly endowed. The
term _schools of medicine_ was proscribed as too aristocratical;
they were distinguished by the ridiculous appellation of _schools of
health_. The _Polytechnic School_ was next instituted, as a kind of
preparation for the exercise of the military profession, where young
men could be instructed in mathematics and natural philosophy, to make
them fit for entering the schools of the artillery, of engineers,
and of the marine. The _Central Schools_ was another institution for
which France was indebted to the efforts of Fourcroy. The idea was
good, though it was very imperfectly executed. It was to establish a
kind of university in every department, for which the young men were
to be prepared by a sufficient number of inferior schools scattered
through the department. But unfortunately these inferior schools were
never properly established or endowed; and even the central schools
themselves were never supplied with proper masters. Indeed, it was
found impossible to furnish such a number of masters at once. On that
account, an institution was established in Paris, called the _Normal
School_, for the express purpose of educating a sufficient number of
masters to supply the different central schools.

Fourcroy, either as a member of the Convention or of the _Council of
the Ancients_, took an active part in all these institutions, as far
as regarded the plan and the establishment. He was equally concerned
in the establishment of the Institute and of the _Musée d'Histoire
Naturelle_. This last was endowed with the utmost liberality, and
Fourcroy was one of the first professors; as he was also in the School
of Medicine and the Polytechnic School. He was equally concerned in the
restoration of the university, which constituted one of the most useful
parts of Bonaparte's reign.

The violent exertions which he made in the numerous situations which
he filled, and the prodigious activity which he displayed, gradually
undermined his constitution. He himself was sensible of his approaching
death, and announced it to his friends as an event which would
speedily take place. On the 16th of December, 1809, after signing some
despatches, he suddenly cried out, _Je suis mort_ (_I am dead_), and
dropped lifeless on the ground.

He was twice married: first to Mademoiselle Bettinger, by whom he had
two children, a son and a daughter, who survived him. He was married
for the second time to Madame Belleville, the widow of Vailly, by whom
he had no family. He left but little fortune behind him; and two maiden
sisters, who lived with him, depended afterwards for their support on
his friend M. Vauquelin.

Notwithstanding the vast quantity of papers which he published, it
will be admitted, without dispute, that the prodigious reputation
which he enjoyed during his lifetime was more owing to his eloquence
than to his eminence as a chemist--though even as a chemist he was
far above mediocrity. He must have possessed an uncommon facility
of writing. Five successive editions of his System of Chemistry
appeared, each of them gradually increasing in size and value: the
first being in two volumes and the last in ten. This last edition
he wrote in sixteen months: it contains much valuable information,
and doubtless contributed considerably to the general diffusion of
chemical knowledge. Its style is perhaps too diffuse, and the spirit
of generalizing from particular, and often ill-authenticated facts, is
carried to a vicious length. Perhaps the best of all his productions is
his Philosophy of Chemistry. It is remarkable for its conciseness, its
perspicuity, and the neatness of its arrangement.

Besides these works, and the periodical publication entitled "Le
Médecin éclairé," of which he was the editor, there are above one
hundred and sixty papers on chemical subjects, with his name attached
to them, which appeared in the Memoirs of the Academy and of the
Institute; in the Annales de Chimie, or the Annales de Musée d'Histoire
Naturelle; of which last work he was the original projector. Many of
these papers contained analyses both animal, vegetable, and mineral,
of very considerable value. In most of them, the name of Vauquelin is
associated with his own as the author; and the general opinion is,
that the experiments were all made by Vauquelin; but that the papers
themselves were drawn up by Fourcroy.

It would serve little purpose to go over this long list of papers;
because, though they contributed essentially to the progress of
chemistry, yet they exhibit but few of those striking discoveries,
which at once alter the face of the science, by throwing a flood of
light on every thing around them. I shall merely notice a few of what I
consider as his best papers.

1. He ascertained that the most common biliary calculi are composed of
a substance similar to spermaceti. This substance, in consequence of
a subsequent discovery which he made during the removal of the dead
bodies from the burial-ground of the Innocents at Paris; namely, that
these bodies are converted into a fatty matter, he called _adipocire_.
It has since been distinguished by the name of _cholestine_; and has
been shown to possess properties different from those of adipocire and
spermaceti.

2. It is to him that we are indebted for the first knowledge of the
fact, that the salts of magnesia and ammonia have the property of
uniting together, and forming double salts.

3. His dissertation on the sulphate of mercury contains some good
observations. The same remark applies to his paper on the action of
ammonia on the sulphate, nitrate, and muriate of mercury. He first
described the double salts which are formed.

4. The analysis of urine would have been valuable had not almost
all the facts contained in it been anticipated by a paper of Dr.
Wollaston, published in the Philosophical Transactions. It is to him
that we are indebted for almost all the additions to our knowledge
of calculi since the publication of Scheele's original paper on the
subject.

5. I may mention the process of Fourcroy and Vauquelin for obtaining
pure barytes, by exposing nitrate of barytes to a red heat, as a
good one. They discovered the existence of phosphate of magnesia in
bones, of phosphorus in the brain and in the milts of fishes, and of a
considerable quantity of saccharine matter in the bulb of the common
onion; which, by undergoing a kind of spontaneous fermentation was
converted into _manna_.

In these, and many other similar discoveries, which I think it
unnecessary to notice, we do not know what fell to the share of
Fourcroy and what to Vauquelin; but there is one merit at least to
which Fourcroy is certainly entitled, and it is no small one: he formed
and brought forward Vauquelin, and proved to him, ever after, a most
steady and indefatigable friend. This is bestowing no small panegyric
on his character; for it would have been impossible to have retained
such a friend through all the horrors of the French revolution, if his
own qualities had not been such as to merit so steady an attachment.

Louis Bernard Guyton de Morveau was born at Dijon on the 4th of
January, 1737. His father, Anthony Guyton, was professor of civil
law in the University of Dijon, and descended from an ancient and
respectable family. At the age of seven he showed an uncommon
mechanical turn: being with his father at a small village near Dijon,
he there happened to meet a public officer returning from a sale,
whence he had brought back a clock that had remained unsold on account
of its very bad condition. Morveau supplicated his father to buy it.
The purchase was made for six francs. Young Morveau took it to pieces
and cleaned it, supplied some parts that were wanting, and put it up
again without any assistance. In 1799 this very clock was resold at a
higher price, together with the estate and house in which it had been
originally placed; having during the whole of that time continued to go
in the most satisfactory manner. When only eight years of age, he took
his mother's watch to pieces, cleaned it, and put it up again to the
satisfaction of all parties.

After finishing his preliminary studies in his father's house, he went
to college, and terminated his attendance on it at the age of sixteen.
About this time he was instructed in botany by M. Michault, a friend
of his father, and a naturalist of some eminence. He now commenced law
student in the University of Dijon; and, after three years of intense
application, he went to Paris to acquire a knowledge of the practice of
the law.

While in Paris, he not only attended to law, but cultivated at the same
time several branches of polite literature. In 1756 he paid a visit
to Voltaire, at Ferney. This seems to have inspired him with a love
of poetry, particularly of the descriptive and satiric kind. About a
year afterwards, when only twenty, he published a poem called "Le Rat
Iconoclaste, ou le Jesuite croquée." It was intended to throw ridicule
on a well-known anecdote of the day, and to assist in blowing the fire
that already threatened destruction to the obnoxious order of Jesuits.
The adventure alluded to was this: Some nuns, who felt a strong
predilection for a Jesuit, their spiritual director, were engaged in
their accustomed Christmas occupation of modelling a representation of
a religious mystery, decorated with several small statues representing
the holy personages connected with the subject, and among them that
of the ghostly father; but, to mark their favourite, his statue was
made of loaf sugar. The following day was destined for the triumph of
the Jesuit: but, meanwhile, a rat had devoured the valuable puppet.
The poem is written after the agreeable manner of the celebrated poem,
"Ververt."

At the age of twenty-four he had already pleaded several important
causes at the bar, when the office of advocate-general, at the
parliament of Dijon, was advertised for sale. At that time all public
situations, however important, were sold to the best bidder. His father
having ascertained that this place would be acceptable to his son,
purchased it for forty thousand francs. The reputation of the young
advocate, and his engaging manners, facilitated the bargain.

In 1764 he was admitted an honorary member of the Academy of Sciences,
Arts, and Belles Lettres, of Dijon. Two months after, he presented to
the assembled chamber of the parliament of Burgundy, a memoir on public
instruction, with a plan for a college, on the principles detailed in
his work. The encomiums which every public journal of the time passed
on this production, and the flattering letters which he received, were
unequivocal proofs of its value. In this memoir he endeavoured to
prove that man is _bad_ or _good_, according to the education which he
has received. This doctrine was contrary to the creed of Diderot, who
affirmed, in his Essay on the Life of Seneca, that nature makes wicked
persons, and that the best institutions cannot render them good. But
this mischievous opinion was successfully refuted by Morveau, in a
letter to an anonymous friend.

The exact sciences were so ill taught, and lamely cultivated at Dijon,
during the time of his university education, that after his admission
into the academy his notions on mechanics and natural philosophy were
scanty and inaccurate. Dr. Chardenon was in the habit of reading
memoirs on chemical subjects; and on one occasion Morveau thought
it necessary to hazard some remarks which were ill received by the
doctor, who sneeringly told him that having obtained such success in
literature, he had better rest satisfied with the reputation so justly
acquired, and leave chemistry to those who knew more of the matter.

Provoked at this violent remark, he resolved upon taking an honourable
revenge. He therefore applied himself to the study of Macquer's
Theoretical and Practical Chemistry, and of the Manual of Chemistry
which Beaumé had just published. To the last chemist he also sent an
extensive order for chemical preparations and utensils, with a view
of forming a small laboratory near his office. He began by repeating
many of Beaumé's experiments, and then trying his inexperienced hand
at original researches. He soon found himself strong enough to attack
the doctor. The latter had just been reading a memoir on the analysis
of different kinds of oil; and Morveau combated some of his opinions
with so much skill and sagacity, as astonished every one present. After
the meeting, Dr. Chardenon addressed him thus: "You are born to be an
honour to chemistry. So much knowledge could only have been gained by
genius united with perseverance. Follow your new pursuit, and confer
with me in your difficulties."

But this new pursuit did not prevent Morveau from continuing to
cultivate literature with success. He wrote an _Eloge_ of Charles V. of
France, surnamed _the Wise_, which had been given out as the subject
of a prize, by the academy. A few months afterwards, at the opening of
the session of parliament, he delivered a discourse on the actual state
of jurisprudence; on which subject, three years after, he composed a
more extensive and complete work. No code of laws demanded reform more
urgently than those of France, and none saw more clearly the necessity
of such a reformation.

About this time a young gentleman of Dijon had taken into his house an
adept, who offered, upon being furnished with the requisite materials,
to produce gold in abundance; but, after six months of expensive
and tedious operations (during which period the roguish pretender
had secretly distilled many oils, &c., which he disposed of for his
own profit), the gentleman beginning to doubt the sincerity of his
instructer, dismissed him from his service and sold the whole of his
apparatus and materials to Morveau for a trifling sum.

Soon after he repaired to Paris, to visit the scientific establishments
of that metropolis, and to purchase preparations and apparatus which he
still wanted to enable him to pursue with effect his favourite study.
For this purpose he applied to Beaumé, then one of the most conspicuous
of the French chemists. Pleased with his ardour, Beaumé inquired what
courses of chemistry he had attended. "None," was the answer.--"How
then could you have learned to make experiments, and above all, how
could you have acquired the requisite dexterity?"--"Practice," replied
the young chemist, "has been my master; melted crucibles and broken
retorts my tutors."--"In that case," said Beaumé, "you have not
learned, you have invented."

About this time Dr. Chardenon read a paper before the Dijon Academy
on the causes of the augmentation of weight which metals experience
when calcined. He combated the different explanations which had been
already advanced, and then proceeded to show that it might be accounted
for in a satisfactory manner by the _abstraction_ of phlogiston.
This drew the attention of Morveau to the subject: he made a set of
experiments a few months afterwards, and read a paper on the _phenomena
of the air during combustion_. It was soon after that he made a set of
experiments on the time taken by different substances to absorb or emit
a given quantity of heat. These experiments, if properly followed out,
would have led to the discovery of _specific heat_; but in his hands
they seem to have been unproductive.

In the year 1772 he published a collection of scientific essays under
the title of "Digressions Académiques." The memoirs on _phlogiston_,
_crystallization_, and _solution_, found in this book deserve
particular attention, and show the superiority of Morveau over most of
the chemists of the time.

About this time an event happened which deserves to be stated. It had
been customary in one of the churches of Dijon to bury considerable
numbers of dead bodies. From these an infectious exhalation had
proceeded, which had brought on a malignant disorder, and threatened
the inhabitants of Dijon with something like the plague. All attempts
to put an end to this infectious matter had failed, when Morveau tried
the following method with complete success: A mixture of common salt
and sulphuric acid in a wide-mouthed vessel was put upon chafing-dishes
in various parts of the church. The doors and windows were closed and
left in this state for twenty-four hours. They were then thrown open,
and the chafing-dishes with the mixtures removed. Every remains of the
bad smell was gone, and the church was rendered quite clean and free
from infection. The same process was tried soon after in the prisons
of Dijon, and with the same success. Afterwards chlorine gas was
substituted for muriatic acid gas, and found still more efficacious.
The present practice is to employ chloride of lime, or chloride of
soda, for the purpose of fumigating infected apartments, and the
process is found still more effectual than the muriatic acid gas, as
originally employed by Morveau. The nitric acid fumes, proposed by Dr.
Carmichael Smith, are also efficacious, but the application of them
is much more troublesome and more expensive than of chloride of lime,
which costs very little.

In the year 1774 it occurred to Morveau, that a course of lectures on
chemistry, delivered in his native city, might be useful. Application
being made to the proper authorities, the permission was obtained,
and the necessary funds for supplying a laboratory granted. These
lectures were begun on the 29th of April, 1776, and seem to have been
of the very best kind. Every thing was stated with great clearness,
and illustrated by a sufficient number of experiments. His fame now
began to extend, and his name to be known to men of science in every
part of Europe; and, in consequence, he began to experience the fate of
almost all eminent men--to be exposed to the attacks of the malignant
and the envious. The experiments which he exhibited to determine the
properties of _carbonic acid gas_ drew upon him the animadversions of
several medical men, who affirmed that this gas was nothing else than a
peculiar state of sulphuric acid. Morveau answered these animadversions
in two pamphlets, and completely refuted them.

About this time he got metallic conductors erected on the house of the
Academy at Dijon. On this account he was attacked violently for his
presumption in disarming the hand of the Supreme Being. A multitude of
fanatics assembled to pull down the conductors, and they would probably
have done much mischief, had it not been for the address of M. Maret,
the secretary, who assured them that the astonishing virtue of the
apparatus resided in the gilded point, which had purposely been sent
from Rome by the holy father! Will it excite any surprise, that within
less than twenty years after this the mass of the French people not
only renounced the Christian religion, and the spiritual dominion of
the pope, but declared themselves atheists!

In 1777 Morveau published the first volume of a course of chemistry,
which was afterwards followed by three other volumes, and is known
by the name of "Elémens de Chimie de l'Académie de Dijon." This book
was received with universal approbation, and must have contributed
very much to increase the value of his lectures. Indeed, a text-book
is essential towards a successful course of lectures: it puts it in
the power of the students to understand the lecture if they be at
the requisite pains; and gives them a means of clearing up their
difficulties, when any such occur. I do not hesitate to say, that a
course of chemical lectures is twice as valuable when the students are
furnished with a good text-book, as when they are left to interpret the
lectures by their own unassisted exertions.

Soon after he undertook the establishment of a manufacture of saltpetre
upon a large scale. For this he received the thanks of M. Necker,
who was at that time minister of finance, in the name of the King of
France. This manufactory he afterwards gave up to M. Courtois, whose
son still carries it on, and is advantageously known to the public as
the discoverer of _iodine_.

His next object was to make a collection of minerals, and to make
himself acquainted with the science of mineralogy. All this was soon
accomplished. In 1777 he was charged to examine the slate-quarries
and the coal-mines of Burgundy, for which purpose he performed a
mineralogical tour through the province. In 1779 he discovered a
lead-mine in that country, and a few years afterwards, when the
attention of chemists had been drawn to sulphate of barytes and its
base, by the Swedish chemists, he sought for it in Burgundy, and found
it in considerable quantity at Thôte. This enabled him to draw up a
description of the mineral, and to determine the characters of the
base, to which he gave the name of _barote_; afterwards altered to
that of barytes. This paper was published in the third volume of the
Memoirs of the Dijon Academy. In this paper he describes his method of
decomposing sulphate of barytes, by heating it with charcoal--a method
now very frequently followed.

In the year 1779 he was applied to by Pankouke, who meditated the great
project of the _Encyclopédie Méthodique_, to undertake the chemical
articles in that immense dictionary, and the demand was supported by a
letter from Buffon, whose request he did not think that he could with
propriety refuse. The engagement was signed between them in September,
1780. The first half-volume of the chemical part of this Encyclopédie
did not appear till 1786, and Morveau must have been employed during
the interval in the necessary study and researches. Indeed, it is
obvious, from many of the articles, that he had spent a good deal of
time in experiments of research.

The state of the chemical nomenclature was at that period peculiarly
barbarous and defective. He found himself stopped at every corner for
want of words to express his meaning. This state of things he resolved
to correct, and accordingly in 1782 published his first essay on a
new chemical nomenclature. No sooner did this essay appear than it
was attacked by almost all the chemists of Paris, and by none more
zealously than by the chemical members of the academy. Undismayed by
the violence of his antagonists, and satisfied with the rectitude of
his views, and the necessity of the reform, he went directly to Paris
to answer the objections in person. He not only succeeded in convincing
his antagonists of the necessity of reform; but a few years afterwards
prevailed upon the most eminent chemical members of the academy,
Lavoisier, Berthollet, and Fourcroy, to unite with him in rendering
the reform still more complete and successful. He drew up a memoir,
exhibiting a plan of a methodical chemical nomenclature, which was read
at a meeting of the Academy of Sciences, in 1787. Morveau, then, was
in reality the author of the new chemical nomenclature, if we except
a few terms, which had been already employed by Lavoisier. Had he
done nothing more for the science than this, it would deservedly have
immortalized his name. For every one must be sensible how much the new
nomenclature contributed to the subsequent rapid extension of chemical
science.

It was during the repeated conferences held with Lavoisier and the
other two associates that Morveau became satisfied of the truth of
Lavoisier's new doctrine, and that he was induced to abandon the
phlogistic theory. We do not know the methods employed to convert
him. Doubtless both reasoning and experiment were made use of for the
purpose.

It was during this period that Morveau published a French translation
of the Opuscula of Bergman. A society of friends, under his
encouragement, translated the chemical memoirs of Scheele and many
other foreign books of importance, which by their means were made
known to the men of science in France.

In 1783, in consequence of a favourable report by Macquer, Morveau
obtained permission to establish a manufactory of carbonate of soda,
the first of the kind ever attempted in France. It was during the
same year that he published his collection of pleadings at the bar,
among which we find his Discours sur la Bonhomie, delivered at the
opening of the sessions at Dijon, with which he took leave of his
fellow-magistrates, surrendering the insignia of office, as he had
determined to quit the profession of the law.

On the 25th of April, 1784, Morveau, accompanied by President Virly,
ascended from Dijon in a balloon, which he had himself constructed,
and repeated the ascent on the 12th of June following, with a view of
ascertaining the possibility of directing these aerostatic machines,
by an apparatus of his own contrivance. The capacity of the balloon
was 10,498,074 French cubic feet. The effect produced by this bold
undertaking by two of the most distinguished characters in the town was
beyond description. Such ascents were then quite new, and looked upon
with a kind of reverential awe. Though Morveau failed in his attempts
to direct these aerial vessels, yet his method was ingenious and
exceedingly plausible.

In 1786 Dr. Maret, secretary to the Dijon Academy, having fallen a
victim to an epidemic disease, which he had in vain attempted to
arrest, Morveau was appointed perpetual secretary and chancellor of
the institution. Soon after this the first half-volume of the chemical
part of the Encyclopédie Méthodique made its appearance, and drew the
attention of every person interested in the science of chemistry. No
chemical treatise had hitherto appeared worthy of being compared
to it. The article _Acid_, which occupies a considerable part, is
truely admirable; and whether we consider the historical details, the
completeness of the accounts, the accuracy of the description of the
experiments, or the elegance of the style, constitutes a complete model
of what such a work should be. I may, perhaps, be partial, as it was
from this book that I imbibed my own first notions in chemistry, but
I never perused any book with more delight, and when I compared it
with the best chemical books of the time, whether German, French, or
English, its superiority became still more striking.

In the article _Acier_, Morveau had come to the very same conclusions,
with respect to the nature of _steel_, as had been come to by
Berthollet, Monge, and Vandermonde, in their celebrated paper on the
subject, just published in the Memoirs of the Academy. His own article
had been printed, though not published, before the appearance of the
Memoir of the Academicians. This induced him to send an explanation to
Berthollet, which was speedily published in the Journal de Physique.

In September, 1787, he received a visit from Lavoisier, Berthollet,
Fourcroy, Monge, and Vandermonde. Dr. Beddoes, who was travelling
through France at the time, and happened to be in Dijon, joined the
party. The object of the meeting was to discuss several experiments
explanatory of the new doctrine. In 1789 an attempt was made to get
him admitted as a member of the Academy of Sciences; but it failed,
notwithstanding the strenuous exertions of Berthollet and his other
chemical friends.

The French revolution had now broken out, occasioned by the wants of
the state on the one hand, and the resolute determination of the clergy
and the nobility on the other, not to submit to bear any share in the
public burdens. During the early part of this revolution Morveau took
no part whatever in politics. In 1790, when France was divided into
departments, he was named one of a commission by the National Assembly
for the formation of the department of the Côte d'Or. On the 25th of
August, 1791, he received from the Academy of Sciences the annual
prize of 2000 francs, for the most useful work published in the course
of the year. This was decreed him for his Dictionary of Chemistry,
in the Encyclopédie Méthodique. Aware of the pressing necessities of
the state, Morveau seized the opportunity of showing his desire of
contributing towards its relief, by making a patriotic offering of the
whole amount of his prize.

When the election of the second Constitutional Assembly took place,
he was nominated a member by the electoral college of his department.
A few months before, his name had appeared among the list of members
proposed by the assembly, for the election of a governor to the
heir-apparent. All this, together with the dignity of solicitor-general
of the department to which he had recently been raised, not permitting
him to continue his chemical lectures at Dijon, of which he had already
delivered fifteen gratuitous courses, he resigned his chair in favour
of Dr. Chaussier, afterwards a distinguished professor at the Faculty
of Medicine of Paris; and, bidding adieu to his native city, proceeded
to Paris.

On the ever memorable 16th of January, 1793, he voted with the majority
of deputies. He was therefore, in consequence of this vote, a regicide.
During the same year he resigned, in favour of the republic, his
pension of two thousand francs, together with the arrears of that
pension.

In 1794 he received from government different commissions to act with
the French armies in the Low Countries. Charged with the direction
of a great aerostatic machine for warlike purposes, he superintended
that one in which the chief of the staff of General Jourdan and
himself ascended during the battle of Fleurus, and which so materially
contributed to the success of the French arms on that day. On his
return from his various missions, he received from the three committees
of the executive government an invitation to co-operate with several
learned men in the instruction of the _central schools_, and was named
professor of chemistry at the _Ecole Centrale des Travaux publiques_,
since better known under the name of the _Polytechnic School_.

In 1795 he was re-elected member of the Council of Five Hundred, by
the electoral assemblies of Sarthe and Ile et Vilaine. The executive
government, at this time, decreed the formation of the National
Institute, and named him one of the forty-eight members chosen by
government to form the nucleus of that scientific body.

In 1797 he resigned all his public situations, and once more attached
himself exclusively to science and to the establishments for public
instruction. In 1798 he was appointed a provisional director of the
Polytechnic School, to supply the place of Monge, who was then in
Egypt. He continued to exercise its duties during eighteen months,
to the complete satisfaction of every person connected with that
establishment. With much delicacy and disinterestedness, he declined
accepting the salary of 2000 francs attached to this situation, which
he thought belonged to the proper director, though absent from his
duties.

In 1799 Bonaparte appointed him one of the administrators-general
of the Mint; and the year following he was made director of the
Polytechnic School. In 1803 he received the cross of the Legion of
Honour, then recently instituted; and in 1805 was made an officer
of the same order. These honours were intended as a reward for the
advantage which had accrued from the mineral acid fumigations which
he had first suggested. In 1811 he was created a baron of the French
empire.

After having taught in the _Ecole Polytechnique_ for sixteen years, he
obtained leave, on applying to the proper authorities, to withdraw into
the retired station of private life, crowned with years and reputation,
and followed with the blessings of the numerous pupils whom he had
brought up in the career of science. In this situation he continued
about three years, during which he witnessed the downfall of Bonaparte,
and the restoration of the Bourbons. On the 21st of December, 1815, he
was seized with a total exhaustion of strength; and, after an illness
of three days only, expired in the arms of his disconsolate wife, and a
few trusty friends, having nearly completed the eightieth year of his
age. On the 3d of January, 1816, his remains were followed to the grave
by the members of the Institute, and many other distinguished men: and
Berthollet, one of his colleagues, pronounced a short but impressive
funeral oration on his departed friend.

Morveau had married Madame Picardet, the widow of a Dijon academician,
who had distinguished himself by numerous scientific translations from
the Swedish, German, and English languages. The marriage took place
after they were both advanced in life, and he left no children behind
him. His publications on chemical subjects were exceedingly numerous,
and he contributed as much as any of his contemporaries to the
extension of the science; but as he was not the author of any striking
chemical discoveries, it would be tedious to give a catalogue of his
numerous productions which were scattered through the Dijon Memoirs,
the Journal de Physique, and the Annales de Chimie.




CHAPTER IV.

PROGRESS OF ANALYTICAL CHEMISTRY.


Analysis, or the art of determining the constituents of which every
compound is composed, constitutes the essence of chemistry: it was
therefore attempted as soon as the science put on any thing like a
systematic form. At first, with very little success; but as knowledge
became more and more general, chemists became more expert, and
something like regular analysis began to appear. Thus, Brandt showed
that _white vitriol_ is a compound of sulphuric acid and oxide of
zinc; and Margraaf, that _selenite_ or _gypsum_ is a compound of
sulphuric acid and lime. Dr. Black made analyses of several of the
salts of magnesia, so far at least as to determine the nature of the
constituents. For hardly any attempt was made in that early period of
the art to determine the weight of the respective constituents. The
first person who attempted to lay down rules for the regular analysis
of minerals, and to reduce these rules to practice, was Bergman.
This he did in his papers "De Docimasia Minerarum Humida," "De Terra
Gemmarum," and "De Terra Tourmalini," published between the years 1777
and 1780.

To analyze a mineral, or to separate it into its constituent parts, it
is necessary in the first place, to be able to dissolve it in an acid.
Bergman showed that most minerals become soluble in muriatic acid if
they be reduced to a very fine powder, and then heated to redness, or
fused with an alkaline carbonate. After obtaining a solution in this
way he pointed out methods by which the different constituents may be
separated one after another, and their relative quantities determined.
The fusion with an alkaline carbonate required a strong red heat.
An earthenware crucible could not be employed, because at a fusing
temperature it would be corroded by the alkaline carbonate, and thus
the mineral under analysis would be contaminated by the addition of a
quantity of foreign matter. Bergman employed an iron crucible. This
effectually prevented the addition of any earthy matter. But at a red
heat the iron crucible itself is apt to be corroded by the action of
the alkali, and thus the mineral under analysis becomes contaminated
with a quantity of that metal. This iron might easily be separated
again by known methods, and would therefore be of comparatively small
consequence, provided we were sure that the mineral under examination
contained no iron; but when that happens (and it is a very frequent
occurrence), an error is occasioned which we cannot obviate. Klaproth
made a vast improvement in the art of analysis, by substituting
crucibles of fine silver for the iron crucibles of Bergman. The only
difficulty attending their use was, that they were apt to melt unless
great caution was used in heating them. Dr. Wollaston introduced
crucibles of platinum about the beginning of the present century. It
is from that period that we may date the commencement of accurate
analyzing.

Bergman's processes, as might have been expected, were rude and
imperfect. It was Klaproth who first systematized chemical analysis and
brought the art to such a state, that the processes followed could
be imitated by others with nearly the same results, thus offering a
guarantee for the accuracy of the process.

Martin Henry Klaproth, to whom chemistry lies under so many and such
deep obligations, was born at Wernigerode, on the 1st of December,
1743. His father had the misfortune to lose his whole goods by a great
fire, on the 30th of June, 1751, so that he was able to do little
or nothing for the education of his children. Martin was the second
of three brothers, the eldest of whom became a clergyman, and the
youngest private secretary at war, and keeper of the archives of the
cabinet of Berlin. Martin survived both his brothers. He procured such
meagre instruction in the Latin language as the school of Wernigerode
afforded, and he was obliged to procure his small school-fees by
singing as one of the church choir. It was at first his intention to
study theology; but the unmerited hard treatment which he met with
at school so disinclined him to study, that he determined, in his
sixteenth year, to learn the trade of an apothecary. Five years which
he was forced to spend as an apprentice, and two as an assistant in
the public laboratory in Quedlinburg, furnished him with but little
scientific information, and gave him little else than a certain
mechanical adroitness in the most common pharmaceutical preparations.

He always regarded as the epoch of his scientific instruction, the
two years which he spent in the public laboratory at Hanover, from
Easter 1766, till the same time in 1768. It was there that he first
met with some chemical books of merit, especially those of Spielman,
and Cartheuser, in which a higher scientific spirit already breathed.
He was now anxious to go to Berlin, of which he had formed a high idea
from the works of Pott, Henkel, Rose, and Margraaf. An opportunity
presenting itself about Easter, 1768, he was placed as assistant in the
laboratory of Wendland, at the sign of the Golden Angel, in the Street
of the Moors. Here he employed all the time which a conscientious
discharge of the duties of his station left him, in completing his own
scientific education. And as he considered a profounder acquaintance
with the ancient languages, than he had been able to pick up at
the school of Wernigerode, indispensable for a complete scientific
education, he applied himself with great zeal to the study of the
Greek and Latin languages, and was assisted in his studies by Mr.
Poppelbourn, at that time a preacher.

About Michaelmas, 1770, he went to Dantzig, as assistant in the public
laboratory: but in March of the following year he returned to Berlin,
as assistant in the office of the elder Valentine Rose, who was one
of the most distinguished chemists of his day. But this connexion did
not continue long; for Rose died in 1771. On his deathbed he requested
Klaproth to undertake the superintendence of his office. Klaproth not
only superintended this office for nine years with the most exemplary
fidelity and conscientiousness, but undertook the education of the
two sons of Rose, as if he had been their father. The younger died
before reaching the age of manhood: the elder became his intimate
friend, and the associate of all his scientific researches. For several
years before the death of Rose (which happened in 1808) they wrought
together, and Klaproth was seldom satisfied with the results of his
experiments till they had been repeated by Rose.

In the year 1780 Klaproth went through his trials for the office of
apothecary with distinguished applause. His thesis, "On Phosphorus and
distilled Waters," was printed in the Berlin Miscellanies for 1782.
Soon after this, Klaproth bought what had formerly been the Flemming
laboratory in Spandau-street: and he married Sophia Christiana Lekman,
with whom he lived till 1803 (when she died) in a happy state. They had
three daughters and a son, who survived their parents. He continued
in possession of this laboratory, in which he had arranged a small
work-room of his own, till the year 1800, when he purchased the room
of the Academical Chemists, in which he was enabled, at the expense of
the academy, to furnish a better and more spacious apartment for his
labours, for his mineralogical and chemical collection, and for his
lectures.

As soon as he had brought the first arrangements of his office to
perfection--an office which, under his inspection and management,
became the model of a laboratory, conducted upon the most excellent
principles, and governed with the most conscientious integrity, he
published in the various periodical works of Germany, such as "Crell's
Chemical Annals," the "Writings of the Society for the promotion of
Natural Knowledge," "Selle's Contributions to the Science of Nature
and of Medicine," "Köhler's Journal," &c.; a multitude of papers
which soon drew the attention of chemists; for example, his Essay on
Copal--on the Elastic Stone--on Proust's Sel perlée--on the Green Lead
Spar of Tschoppau--on the best Method of preparing Ammonia--on the
Carbonate of Barytes--on the Wolfram of Cornwall--on Wood Tin--on the
Violet Schorl--on the celebrated Aerial Gold--on Apatite, &c. All these
papers, which secured him a high reputation as a chemist, appeared
before 1788, when he was chosen an ordinary member of the physical
class of the Royal Berlin Academy of Sciences. The Royal Academy of
Arts had elected him a member a year earlier. From this time, every
volume of the Memoirs of the Academy, and many other periodical works
besides, contained numerous papers by this accomplished chemist; and
there is not one of them which does not furnish us with a more exact
knowledge of some one of the productions of nature or art. He has
either corrected false representations, or extended views that were
before partially known, or has revealed the composition and mixture
of the parts of bodies, and has made us acquainted with a variety of
new elementary substances. Amidst all these labours, it is difficult
to say whether we should most admire the fortunate genius, which, in
all cases, readily and easily divined the point where any thing of
importance lay concealed; or the acuteness which enabled him to find
the best means of accomplishing his object; or the unceasing labour
and incomparable exactness with which he developed it; or the pure
scientific feeling under which he acted, and which was removed at the
utmost possible distance from every selfish, every avaricious, and
every contentious purpose.

In the year 1795 he began to collect his chemical works which lay
scattered among so many periodical publications, and gave them to
the world under the title of "Beitrage zur Chemischen Kenntniss der
Mineralkörper" (Contributions to the Chemical Knowledge of Mineral
Bodies). Of this work, which consists of six volumes, the last was
published in 1815, about a year before the author's death. It contains
no fewer than two hundred and seven treatises, the most valuable part
of all that Klaproth had done for chemistry and mineralogy. It is a
pity that the sale of this work did not permit the publication of a
seventh volume, which would have included the rest of his papers, which
he had not collected, and given us a good index to the whole work,
which would have been of great importance to the practical chemist.
There is, indeed, an index to the first five volumes; but it is meagre
and defective, containing little else than the names of the substances
on which his experiments were made.

Besides his own works, the interest which he took in the labours of
others deserves to be noticed. He superintended a new edition of Gren's
Manual of Chemistry, remarkable not so much for what he added as for
what he took away and corrected. The part which he took in Wolff's
Chemical Dictionary was of great importance. The composition of every
particular treatise was by Professor Wolff; but Klaproth read over
every important article before it was printed, and assisted the editor
on all occasions with the treasures of his experience and knowledge.
Nor was he less useful to Fischer in his translation of Berthollet on
Affinity and on Chemical Statics.

These meritorious services, and the lustre which his character and
discoveries conferred on his country were duly appreciated by his
sovereign. In 1782 he had been made assessor in the Supreme College of
Medicine and of Health, which then existed. At a more recent period
he enjoyed the same rank in the Supreme Council of Medicine and of
Health; and when this college was subverted, in 1810, he became a
member of the medical deputation attached to the ministry of the
interior. He was also a member of the perpetual court commission for
medicines. His lectures, too, procured for him several municipal
situations. As soon as the public became acquainted with his great
chemical acquirements he was permitted to give yearly two private
courses of lectures on chemistry; one for the officers of the royal
artillery corps, the other for officers not connected with the army,
who wished to accomplish themselves for some practical employment.
Both of these lectures assumed afterwards a municipal character. The
former led to his appointment as professor of the Artillery Academy
instituted at Tempelhoff; and, after its dissolution, to his situation
as professor in the Royal War School. The other lecture procured for
him the professorship of chemistry in the Royal Mining Institute. On
the establishment of the university, Klaproth's lectures became those
of the university, and he himself was appointed ordinary professor of
chemistry, and member of the academical senate. From 1797 to 1810 he
was an active member of a small scientific society, which met yearly
during a few weeks for the purpose of discussing the more recondite
mysteries of the science. In the year 1811, the King of Prussia added
to all his other honours the order of the Red Eagle of the third class.

Klaproth spent the whole of a long life in the most active and
conscientious discharge of all the duties of his station, and in an
uninterrupted course of experimental investigations. He died at Berlin
on the 1st of January, 1817, in the 70th year of his age.

Among the remarkable traits in his character was his incorruptible
regard for every thing that he believed to be true, honourable,
and good; his pure love of science, with no reference whatever to
any selfish, ambitious, and avaricious feeling; his rare modesty,
undebased by the slightest vainglory or boasting. He was benevolently
disposed towards all men, and never did a slighting or contemptuous
word respecting any person fall from him. When forced to blame, he did
it briefly, and without bitterness, for his blame always applied to
actions, not to persons. His friendship was never the result of selfish
calculation, but was founded on his opinion of the personal worth of
the individual. Amidst all the unpleasant accidents of his life,
which were far from few, he evinced the greatest firmness of mind.
In his common behaviour he was pleasant and composed, and was indeed
rather inclined to a joke. To all this may be added a true religious
feeling, so uncommon among men of science of his day. His religion
consisted not in words and forms, not in positive doctrines, nor in
ecclesiastical observances, which, however, he believed to be necessary
and honourable; but in a zealous and conscientious discharge of all
his duties, not only of those which are imposed by the laws of men,
but of those holy duties of love and charity, which no human law, but
only that of God can command, and without which the most enlightened of
men is but "as sounding brass, or a tinkling cymbal." He early showed
this religious feeling by the honourable care which he bestowed on the
education of the children of Valentine Rose. Nor did he show less care
at an after-period towards his assistants and apprentices, to whom he
refused no instruction, and in whose success he took the most active
concern. He took a pleasure in every thing that was good and excellent,
and felt a lively interest in every undertaking which he believed to
be of general utility. He was equally removed from the superstition
and infidelity of his age, and carried the principles of religion, not
on his lips, but in the inmost feelings of his heart, from whence they
emanated in actions which pervaded and ennobled his whole being and
conduct.

When we take a view of the benefits which Klaproth conferred upon
chemistry, we must not look so much at the new elementary substances
which he discovered, though they must not be forgotten, as at the new
analytical methods which he introduced, the precision, and neatness,
and order, and regularity with which his analyses were conducted, and
the scrupulous fidelity with which every thing was faithfully stated as
he found it.

1. When a mineral is subjected to analysis, whatever care we take
to collect all the constituents, and to weigh them without losing
any portion whatever, it is generally found that the sum of the
constituents obtained fall a little short of the weight of the mineral
employed in the analysis. Thus, if we take 100 grains of any mineral,
and analyze it, the weights of all the constituents obtained added
together will rarely make up 100 grains, but generally somewhat
less; perhaps only 99, or even 98 grains. But some cases occur, when
the analysis of 100 grains of a mineral gives us constituents that
weigh, when added together, more than 100 grains; perhaps 105, or, in
some rare cases, as much as 110. It was the custom with Bergman, and
other analysts of his time, to consider this deficiency or surplus as
owing to errors in the analysis, and therefore to slur it over in the
statement of the analysis, by bringing the weight of the constituents,
by calculation, to amount exactly to 100 grains. Klaproth introduced
the method of stating the results exactly as he got them. He gives the
weight of mineral employed in all his analyses, and the weight of each
constituent extracted. These weights, added together, generally show a
loss, varying from two per cent. to a half per cent. This improvement
may appear at first sight trifling; yet I am persuaded that to it
we are indebted for most of the subsequent improvements introduced
into analytical chemistry. If the loss sustained was too great, it
was obvious either that the analysis had been badly performed, or
that the mineral contains some constituent which had been overlooked,
and not obtained. This laid him under the necessity of repeating the
analysis; and if the loss continued, he naturally looked out for some
constituent which his analysis had not enabled him to obtain. It was
in this way that he discovered the presence of potash in minerals; and
Dr. Kennedy afterwards, by following out his processes, discovered
soda as a constituent. It was in this way that water, phosphoric acid,
arsenic acid, fluoric acid, boracic acid, &c., were also found to exist
as constituents in various mineral bodies, which, but for the accurate
mode of notation introduced by Klaproth, would have been overlooked and
neglected.

2. When Klaproth first began to analyze mineral bodies, he found
it extremely difficult to bring them into a state capable of being
dissolved in acids, without which an accurate analysis was impossible.
Accordingly corundum, adamantine spar, and the zircon, or hyacinth,
baffled his attempts for a considerable time, and induced him to
consider the earth of corundum as of a peculiar nature. He obviated
this difficulty by reducing the mineral to an extremely fine powder,
and, after digesting it in caustic potash ley till all the water was
dissipated, raising the temperature, and bringing the whole into a
state of fusion. This fusion must be performed in a silver crucible.
Corundum, and every other mineral which had remained insoluble after
fusion with an alkaline carbonate, was found to yield to this new
process. This was an improvement of considerable importance. All
those stony minerals which contain a notable proportion of silica, in
general become soluble after having been kept for some time in a state
of ignition with twice their weight of carbonate of soda. At that
temperature the silica of the mineral unites with the soda, and the
carbonic acid is expelled. But when the quantity of silica is small,
or when it is totally absent, heating with carbonate of soda does not
answer so well. With such minerals, caustic potash or soda may be
substituted with advantage; and there are some of them that cannot
be analyzed without having recourse to that agent. I have succeeded
in analyzing corundum and chrysoberyl, neither of which, when pure,
contain any silica, by simply heating them in carbonate of soda; but
the process does not succeed unless the minerals be reduced to an
exceedingly minute powder.

3. When Klaproth discovered potash in the idocrase, and in some other
minerals, it became obvious that the old mode of rendering minerals
soluble in acids by heating them with caustic potash, or an alkaline
carbonate, could answer only for determining the quantity of silica,
and of earths or oxides, which the mineral contained; but that it could
not be used when the object was to determine its potash. This led him
to substitute _carbonate of barytes_ instead of potash or soda, or
their carbonates. After having ascertained the quantity of silica,
and of earths, and metallic oxides, which the mineral contained, his
last process to determine the potash in it was conducted in this way:
A portion of the mineral reduced to a fine powder was mixed with four
or five times its weight of carbonate of barytes, and kept for some
time (in a platinum crucible) in a red heat. By this process, the whole
becomes soluble in muriatic acid. The muriatic acid solution is freed
from silica, and afterwards from barytes, and all the earths and oxides
which it contains, by means of carbonate of ammonia. The liquid, thus
freed from every thing but the alkali, which is held in solution by the
muriatic acid, and the ammonia, used as a precipitant, is evaporated
to dryness, and the dry mass, cautiously heated in a platinum crucible
till the ammoniacal salts are driven off. Nothing now remains but the
potash, or soda, in combination with muriatic acid. The addition of
muriate of platinum enables us to determine whether the alkali be
potash or soda: if it be potash, it occasions a yellow precipitate; but
nothing falls if the alkali be soda.

This method of analyzing minerals containing potash or soda is commonly
ascribed to Rose. Fescher, in his Eloge of Klaproth, informs us that
Klaproth said to him, more than once, that he was not quite sure
whether he himself, or Rose, had the greatest share in bringing this
method to a state of perfection. From this, I think it not unlikely
that the original suggestion might have been owing to Rose, but that it
was Klaproth who first put it to the test of experiment.

The objection to this mode of analyzing is the high price of the
carbonate of barytes. This is partly obviated by recovering the barytes
in the state of carbonate; and this, in general, may be done, without
much loss. Berthier has proposed to substitute oxide of lead for
carbonate of barytes. It answers very well, is sufficiently cheap,
and does not injure the crucible, provided the oxide of lead be mixed
previously with a little nitrate of lead, to oxidize any fragments
of metallic lead which it may happen to contain. Berthier's mode,
therefore, in point of cheapness, is preferable to that of Klaproth.
It is equally efficacious and equally accurate. There are some other
processes which I myself prefer to either of these, because I find them
equally easy, and still less expensive than either carbonate of barytes
or oxide of lead. Davy's method with boracic acid is exceptionable, on
account of the difficulty of separating the boracic acid completely
again.

4. The mode of separating iron and manganese from each other employed
by Bergman was so defective, that no confidence whatever can be placed
in his results. Even the methods suggested by Vauquelin, though
better, are still defective. But the process followed by Klaproth is
susceptible of very great precision. He has (we shall suppose) the
mixture of iron and manganese to be separated from each other, in
solution, in muriatic acid. The first step of the process is to convert
the protoxide of iron (should it be in that state) into peroxide.
For this purpose, a little nitric acid is added to the solution, and
the whole heated for some time. The liquid is now to be rendered as
neutral as possible; first, by driving off as much of the excess of
acid as possible, by concentrating the liquid; and then by completing
the neutralization, by adding very dilute ammonia, till no more can be
added without occasioning a permanent precipitation. Into the liquid
thus neutralized, succinate or benzoate of ammonia is dropped, as long
as any precipitate appears. By this means, the whole peroxide of iron
is thrown down in combination with succinic, or benzoic acid, while
the whole manganese remains in solution. The liquid being filtered, to
separate the benzoate of iron, the manganese may now (if nothing else
be in the liquid) be thrown down by an alkaline carbonate; or, if the
liquid contain magnesia, or any other earthy matter, by hydrosulphuret
of ammonia, or chloride of lime.

This process was the contrivance of Gehlen; but it was made known to
the public by Klaproth, who ever after employed it in his analyses.
Gehlen employed succinate of ammonia; but Hisinger afterwards showed
that benzoate of ammonia might be substituted without any diminution of
the accuracy of the separation. This last salt, being much cheaper than
succinate of ammonia, answers better in this country. In Germany, the
succinic acid is the cheaper of the two, and therefore the best.

5. But it was not by new processes alone that Klaproth improved the
mode of analysis, though they were numerous and important; the
improvements in the apparatus contributed not less essentially to the
success of his experiments. When he had to do with very hard minerals,
he employed a mortar of flint, or rather of agate. This mortar he,
in the first place, analyzed, to determine exactly the nature of the
constituents. He then weighed it. When a very hard body is pounded in
such a mortar, a portion of the mortar is rubbed off, and mixed with
the pounded mineral. What the quantity thus abraded was, he determined
by weighing the mortar at the end of the process. The loss of weight
gave the portion of the mortar abraded; and this portion must be mixed
with the pounded mineral.

When a hard stone is pounded in an agate mortar it is scarcely possible
to avoid losing a little of it. The best method of proceeding is to
mix the matter to be pounded (previously reduced to a coarse powder
in a diamond mortar) with a little water. This both facilitates the
trituration, and prevents any of the dust from flying away; and not
more than a couple of grains of the mineral should be pounded at once.
Still, owing to very obvious causes, a little of the mineral is sure
to be lost during the pounding. When the process is finished, the
whole powder is to be exposed to a red heat in a platinum crucible,
and weighed. Supposing no loss, the weight should be equal to the
quantity of the mineral pounded together with the portion abraded
from the mortar. But almost always the weight will be found less than
this. Suppose the original weight of the mineral before pounding was
_a_, and the quantity abraded from the mortar 1; then, if nothing were
lost, the weight should be _a_ + 1; but we actually find it only _b_, a
quantity less than _a_ + 1. To determine the weight of matter abraded
from the mortar contained in this powder, we say _a_ + 1: _b_:: 1:
_x_, the quantity from the mortar in our powder, and _x_ = _b_/_a_
+ 1. In performing the analysis, Klaproth attended to this quantity,
which was silica, and subtracted it. Such minute attention may appear,
at first sight superfluous; but it is not so. In analyzing sapphire,
chrysoberyl, and some other very hard minerals, the quantity of silica
abraded from the mortar sometimes amounts to five per cent. of the
weight of the mineral; and if we were not to attend to the way in which
this silica has been introduced into the powder, we should give an
erroneous view of the constitution of the mineral under analysis. All
the analyses of chrysoberyl hitherto published, give a considerable
quantity of silica as a constituent of it. This silica, if really found
by the analysts, must have been introduced from the mortar, for pure
chrysoberyl contains no silica whatever, but is a definite compound of
glucina, alumina, and oxide of iron.

When Klaproth operated with fire, he always selected his vessels,
whether of earthenware, glass, plumbago, iron, silver, or platinum,
upon fixed principles; and showed more distinctly than chemists had
previously been aware of, what an effect the vessel frequently has upon
the result. He also prepared his reagents with great care, to ensure
their purity; for obtaining several of which in their most perfect
state, he invented several efficient methods. It is to the extreme care
with which he selected his minerals for analysis, and to the purity
of his reagents, and the fitness of his vessels for the objects in
view, that the great accuracy of his analyses is to be, in a great
measure, ascribed. He must also have possessed considerable dexterity
in operating, for when he had in view to determine any particular point
with accuracy, his results came, in general, exceedingly near the
truth. I may notice, as an example of this, his analysis of sulphate
of barytes, which was within about one-and-a-half per cent. of absolute
correctness. When we consider the looseness of the data which chemists
were then obliged to use, we cannot but be surprised at the smallness
of the error. Berzelius, in possession of better data, and possessed of
much dexterity, and a good apparatus, when he analyzed this salt many
years afterwards, committed an error of a half per cent.

Klaproth, during a very laborious life, wholly devoted to analytical
chemistry, entirely altered the face of mineralogy. When he began
his labours, chemists were not acquainted with the true composition
of a single mineral. He analyzed above 200 species, and the greater
number of them with so much accuracy, that his successors have, in
most cases, confirmed the results which he obtained. The analyses
least to be depended on, are of those minerals which contain both lime
and magnesia; for his process for separating lime and magnesia from
each other was not a good one; nor am I sure that he always succeeded
completely in separating silica and magnesia from each other. This
branch of analysis was first properly elucidated by Mr. Chenevix.

6. Analytical chemistry was, in fact, systematized by Klaproth; and it
is by studying his numerous and varied analyses, that modern chemists
have learned this very essential, but somewhat difficult art; and have
been able, by means of still more accurate data than he possessed,
to bring it to a still greater degree of perfection. But it must not
be forgotten, that Klaproth was in reality the creator of this art,
and that on that account the greatest part of the credit due to the
progress that has been made in it belongs to him.

It would be invidious to point out the particular analyses which are
least exact; perhaps they ought rather to be ascribed to an unfortunate
selection of specimens, than to any want of care or skill in the
operator. But, during his analytical processes, he discovered a variety
of new elementary substances which it may be proper to enumerate.

In 1789 he examined a mineral called _pechblende_, and found in it
the oxide of a new metal, to which he gave the name of _uranium_.
He determined its characters, reduced it to the metallic state, and
described its properties. It was afterwards examined by Richter,
Bucholz, Arfvedson, and Berzelius.

It was in the same year, 1789, that he published his analysis of the
zircon; he showed it to be a compound of silica and a new earth, to
which he gave the name of zirconia. He determined the properties of
this new earth, and showed how it might be separated from other bodies
and obtained in a state of purity. It has been since ascertained,
that it is a metallic oxide, and the metallic basis of it is now
distinguished by the name of _zirconium_. In 1795 he showed that the
_hyacinth_ is composed of the same ingredients as the zircon; and that
both, in fact, constitute only one species. This last analysis was
repeated by Morveau, and has been often confirmed by modern analytical
chemists.

It was in 1795 that he analyzed what was at that time called _red
schorl_, and now _titanite_. He showed that it was the oxide of a new
metallic body, to which he gave the name of _titanium_. He described
the properties of this new body, and pointed out its distinctive
characters. It must not be omitted, however, that he did not succeed in
obtaining oxide of titanium, or _titanic acid_, as it is now called, in
a state of purity. He was not able to separate a quantity of oxide of
iron, with which it was united, and which gave it a reddish colour. It
was first obtained pure by H. Rose, the son of his friend and pupil,
who took so considerable a part in his scientific investigations.

Titanium, in the metallic state, was some years ago discovered by Dr.
Wollaston, in the slag at the bottom of the iron furnace, at Merthyr
Tydvil, in Wales. It is a yellow-coloured, brittle, but very hard
metal, possessed of considerable beauty; but not yet applied to any
useful purpose.

In 1797 he examined the menachanite, a black sand from Cornwall, which
had been subjected to a chemical analysis by Gregor, in 1791, who had
extracted from it a new metallic substance, which Kirwan distinguished
by the name of _menachine_. Klaproth ascertained that the new metal
of Gregor was the very same as his own titanium, and that menachanite
is a compound of titanic acid and oxide of iron. Thus Mr. Gregor had
anticipated him in the discovery of titanium, though he was not aware
of the circumstance till two years after his own experiments had been
published.

In the year 1793 he published a comparative set of experiments on the
nature of carbonates of barytes and strontian; showing that their
bases are two different earths, and not the same, as had been hitherto
supposed in Germany. This was the first publication on strontian which
appeared on the continent; and Klaproth seems to have been ignorant of
what had been already done on it in Great Britain; at least, he takes
no notice of it in his paper, and it was not his character to slur over
the labours of other chemists, when they were known to him. Strontian
was first mentioned as a peculiar earth by Dr. Crawford, in his paper
on the medicinal properties of the muriate of barytes, published in
1790. The experiments on which he founded his opinions were made, he
informs us, by Mr. Cruikshanks. A paper on the same subject, by Dr.
Hope, was read to the Royal Society of Edinburgh, in 1793; but they had
been begun in 1791. In this paper Dr. Hope establishes the peculiar
characters of strontian, and describes its salts with much precision.

Klaproth had been again anticipated in his experiments on strontian;
but he could not have become aware of this till afterwards. For his own
experiments were given to the public before those of Dr. Hope.

On the 25th of January, 1798, his paper on the gold ores of
Transylvania was read at a meeting of the Academy of Sciences at
Berlin. During his analysis of these ores, he detected a new white
metal, to which he gave the name of _tellurium_. Of this metal he
describes the properties, and points out its distinguishing characters.

These ores had been examined by Muller, of Reichenstein, in the year
1782; and he had extracted from them a metal which he considered as
differing from every other. Not putting full confidence in his own
skill, he sent a specimen of his new metal to Bergman, requesting him
to examine it and give his opinion respecting its nature. All that
Bergman did was to show that the metallic body which he had got was not
antimony, to which alone, of all known metals, it bore any resemblance.
It might be inferred from this, that Muller's metal was new. But
the subject was lost sight of, till the publication of Klaproth's
experiments, in 1802, recalled it to the recollection of chemists.
Indeed, Klaproth relates all that Muller had done, with the most
perfect fairness.

In the year 1804 he published the analysis of a red-coloured mineral,
from Bastnäs in Sweden, which had been at one time confounded with
tungsten; but which the Elhuyarts had shown to contain none of that
metal. Klaproth showed that it contained a new substance, as one of
its constituents, which he considered as a new earth, and which he
called _ochroita_, because it forms coloured salts with acids. Two
years after, another analysis of the same mineral was published by
Berzelius and Hisinger. They considered the new substance which the
mineral contained as a metallic oxide, and to the unknown metallic base
they gave the name of _cerium_, which has been adopted by chemists
in preference to Klaproth's name. The characters of oxide of cerium
given by Berzelius and Hisinger, agree with those given by Klaproth
to ochroita, in all the essential circumstances. Of course Klaproth
must be considered as the discoverer of this new body. The distinction
between _earth_ and _metallic oxide_ is now known to be an imaginary
one. All the substances formerly called earths are, in fact, metallic
oxides.

Besides these new substances, which he detected by his own labours,
he repeated the analyses of others, and confirmed and extended the
discoveries they had made. Thus, when Vauquelin discovered the new
earth _glucina_, in the emerald and beryl, he repeated the analysis
of these minerals, confirmed the discovery of Vauquelin, and gave a
detailed account of the characters and properties of glucina. Gadolin
had discovered another new earth in the mineral called gadolinite. This
discovery was confirmed by the analysis of Ekeberg, who distinguished
the new earth by the name of yttria. Klaproth immediately repeated
the analysis of the gadolinite, confirmed the results of Ekeberg's
analysis, and examined and described the properties of _yttria_.

When Dr. Kennedy discovered soda in basalt, Klaproth repeated the
analysis of this mineral, and confirmed the results obtained by the
Edinburgh analyst.

But it would occupy too much room, if I were to enumerate every example
of such conduct. Whoever will take the trouble to examine the different
volumes of the Beitrage, will find several others not less striking or
less useful.

The service which Klaproth performed for mineralogy, in Germany, was
performed equally in France by the important labours of M. Vauquelin.
It was in France, in consequence of the exertions of Romé de Lisle,
and the mathematical investigations of the Abbé Hauy, respecting
the structure of crystals, which were gradually extended over the
whole mineral kingdom, that the reform in mineralogy, which has now
become in some measure general, originated. Hauy laid it down as a
first principle, that every mineral species is composed of the same
constituents united in the same proportion. He therefore considered
it as an object of great importance, to procure an exact chemical
analysis of every mineral species. Hitherto no exact analysis of
minerals had been performed by French chemists; for Sage, who was the
chemical mineralogist connected with the academy, satisfied himself
with ascertaining the nature of the constituents of minerals, without
determining their proportions. But Vauquelin soon displayed a knowledge
of the mode of analysis, and a dexterity in the use of the apparatus
which he employed, little less remarkable than that of Klaproth himself.

Of Vauquelin's history I can give but a very imperfect account, as I
have not yet had an opportunity of seeing any particulars of his life.
He was a peasant-boy of Normandy, with whom Fourcroy accidentally met.
He was pleased with his quickness and parts, and delighted with the
honesty and integrity of his character. He took him with him to Paris,
and gave him the superintendence of his laboratory. His chemical
knowledge speedily became great, and his practice in experimenting
gave him skill and dexterity: he seems to have performed all the
analytical experiments which Fourcroy was in the habit of publishing.
He speedily became known by his publications and discoveries. When the
scientific institutions were restored or established, after the death
of Robespierre, Vauquelin became a member of the Institute and chemist
to the School of Mines. He was made also assay-master of the Mint.
He was a professor of chemistry in Paris, and delivered, likewise,
private lectures, and took in practical pupils into his laboratory.
His laboratory was of considerable size, and he was in the habit of
preparing both medicines and chemical reagents for sale. It was he
chiefly that supplied the French chemists with phosphorus, &c., which
cannot be conveniently prepared in a laboratory fitted up solely for
scientific purposes.

Vauquelin was by far the most industrious of all the French chemists,
and has published more papers, consisting of mineral, vegetable, and
animal analyses, than any other chemist without exception. When he had
the charge of the laboratory of the School of Mines, Hauy was in the
habit of giving him specimens of all the different minerals which he
wished analyzed. The analyses were conducted with consummate skill,
and we owe to him a great number of improvements in the methods of
analysis. He is not entitled to the same credit as Klaproth, because he
had the advantage of many analyses of Klaproth to serve him as a guide.
But he had no model before him in France; and both the apparatus used
by him, and the reagents which he employed, were of his own contrivance
and preparation. I have sometimes suspected that his reagents were not
always very pure; but I believe the true reason of the unsatisfactory
nature of many of his analyses, is the bad choice made of the specimens
selected for analysis. It is obvious from his papers, that Vauquelin
was not a mineralogist; for he never attempts a description of the
mineral which he subjects to analysis, satisfying himself with the
specimen put into his hands by Hauy. Where that specimen was pure, as
was the case with emerald and beryl, his analysis is very good; but
when the specimen was impure or ill-chosen, then the result obtained
could not convey a just notion of the constituents of the mineral.
That Hauy would not be very difficult to please in his selection of
specimens, I think myself entitled to infer from the specimens of
minerals contained in his own cabinet, many of which were by no means
well selected. I think, therefore, that the numerous analyses published
by Vauquelin, in which the constituents assigned by him are not those,
or, at least, not in the same proportions, as have been found by
succeeding analysts, are to be ascribed, not to errors in the analysis,
which, on the contrary, he always performed carefully, and with the
requisite attention to precision, but to the bad selection of specimens
put into his hand by Hauy, or those other individuals who furnished him
with the specimens which he employed in his analyses. This circumstance
is very much to be deplored; because it puts it out of our power to
confide in an analysis of Vauquelin, till it has been repeated and
confirmed by somebody else.

Vauquelin not only improved the analytical methods, and reduced the art
to a greater degree of simplicity and precision, but he discovered,
likewise, new elementary bodies.

The red lead ore of Siberia had early drawn the attention of chemists,
on account of its beauty; and various attempts had been made to analyze
it. Among others, Vauquelin tried his skill upon it, in 1789, in
concert with M. Macquart, who had brought specimens of it from Siberia;
but at that time he did not succeed in determining the nature of the
acid with which the oxide of lead was combined in it. He examined
it again in 1797, and now succeeded in separating an acid to which,
from the beautiful coloured salts which it forms, he gave the name of
_chromic_. He determined the properties of this acid, and showed that
its basis was a new metal to which he gave the name of _chromium_. He
succeeded in obtaining this metal in a separate state, and showed that
its protoxide is an exceedingly beautiful green powder. This discovery
has been of very great importance to different branches of manufacture
in this country. The green oxide is used pretty extensively in painting
green on porcelain. It constitutes an exceedingly beautiful green
pigment, very permanent, and easily applied. The chromic acid, when
combined with oxide of lead, forms either a yellow or an orange colour
upon cotton cloth, both very fixed and exceedingly beautiful colours.
In that way it is extensively used by the calico-printers; and the
bichromate of potash is prepared, in a crystalline form, to a very
considerable amount, both in Glasgow and Lancashire, and doubtless in
other places.

Vauquelin was requested by Hauy to analyze the _beryl_, a beautiful
light-green mineral, crystallized in six-sided prisms, which occurs
not unfrequently in granite rocks, especially in Siberia. He found it
to consist chiefly of silica, united to alumina, and to another earthy
body, very like alumina in many of its properties, but differing in
others. To this new earth he gave the name of _glucina_, on account
of the sweet taste of its salts; a name not very appropriate, as
alumina, yttria, lead, protoxide of chromium, and even protoxide of
iron, form salts which are distinguished by a sweet taste likewise.
This discovery of glucina confers honour on Vauquelin, as it shows
the care with which his analyses must have been conducted. A careless
experimenter might easily have confounded _glucina_ with _alumina_.
Vauquelin's mode of distinguishing them was, to add sulphate of potash
to their solution in sulphuric acid. If the earth in solution was
alumina, crystals of alum would form in the course of a short time; but
if the earth was glucina, no such crystals would make their appearance,
alumina being the basis of alum, and not glucina. He showed, too, that
glucina is easily dissolved in a solution of carbonate of ammonia,
while alumina is not sensibly taken up by that solution.

Vauquelin died in 1829, after having reached a good old age. His
character was of the very best kind, and his conduct had always been
most exemplary. He never interfered with politics, and steered his way
through the bloody period of the revolution, uncontaminated by the
vices or violence of any party, and respected and esteemed by every
person.

Mr. Chenevix deserves also to be mentioned as an improver of analytical
chemistry. He was an Irish gentleman, who happened to be in Paris
during the reign of terror, and was thrown into prison and put into the
same apartment with several French chemists, whose whole conversation
turned upon chemical subjects. He caught the infection, and, after
getting out of prison, began to study the subject with much energy and
success, and soon distinguished himself as an analytical chemist.

His analysis of corundum and sapphire, and his observations on the
affinity between magnesia and silica, are valuable, and led to
considerable improvements in the method of analysis. His analyses of
the arseniates of copper, though he demonstrated that several different
species exist, are not so much to be depended on; because his method
of separating and estimating the quantity of arsenic acid is not
good. This difficult branch of analysis was not fully understood till
afterwards.

Chenevix was for several years a most laborious and meritorious
chemical experimenter. It is much to be regretted that he should
have been induced, in consequence of the mistake into which he fell
respecting palladium, to abandon chemistry altogether. Palladium was
originally made known to the public by an anonymous handbill which was
circulated in London, announcing that _palladium_, or new silver, was
on sale at Mrs. Forster's, and describing its properties. Chenevix, in
consequence of the unusual way in which the discovery was announced,
naturally considered it as an imposition on the public. He went to
Mrs. Forster's, and purchased the whole palladium in her possession,
and set about examining it, prepossessed with the idea that it was an
alloy of some two known metals. After a laborious set of experiments,
he considered that he had ascertained it to be a compound of platinum
and mercury, or an amalgam of platinum made in a peculiar way, which
he describes. This paper was read at a meeting of the Royal Society by
Dr. Wollaston, who was secretary, and afterwards published in their
Transactions. Soon after this publication, another anonymous handbill
was circulated, offering a considerable price for every grain of
palladium _made_ by Mr. Chenevix's process, or by any other process
whatever. No person appearing to claim the money thus offered, Dr.
Wollaston, about a year after, in a paper read to the Royal Society,
acknowledged himself to have been the discoverer of palladium, and
related the process by which he had obtained it from the solution of
crude platina in aqua regia. There could be no doubt after this, that
palladium was a peculiar metal, and that Chenevix, in his experiments,
had fallen into some mistake, probably by inadvertently employing
a solution of palladium, instead of a solution of his amalgam of
platinum; and thus giving the properties of the one solution to the
other. It is very much to be regretted, that Dr. Wollaston allowed Mr.
Chenevix's paper to be printed, without informing him, in the first
place, of the true history of palladium: and I think that if he had
been aware of the bad consequences that were to follow, and that it
would ultimately occasion the loss of Mr. Chenevix to the science, he
would have acted in a different manner. I have more than once conversed
with Dr. Wollaston on the subject, and he assured me that he did every
thing that he could do, short of betraying his secret, to prevent
Mr. Chenevix from publishing his paper; that he had called upon, and
assured him, that he himself had attempted his process without being
able to succeed, and that he was satisfied that he had fallen into
some mistake. As Mr. Chenevix still persisted in his conviction of the
accuracy of his own experiments after repeated warnings, perhaps it
is not very surprising that Dr. Wollaston allowed him to publish his
paper, though; had he been aware of the consequences to their full
extent, I am persuaded that he would not have done so. It comes to be a
question whether, had Dr. Wollaston informed him of the whole secret,
Mr. Chenevix would have been convinced.

Another chemist, to whom the art of analyzing minerals lies under
great obligations, is Dr. Frederick Stromeyer, professor of chemistry
and pharmacy, in the University of Gottingen. He was originally a
botanist, and only turned his attention to chemistry when he had the
offer of the chemical chair at Gottingen. He then went to Paris, and
studied practical chemistry for some years in Vauquelin's laboratory.
He has devoted most of his attention to the analysis of minerals; and
in the year 1821 published a volume of analyses under the title of
"Untersuchungen über die Mischung der Mineralkörper und anderer damit
verwandten Substanzen." It contains thirty analyses, which constitute
perfect models of analytical sagacity and accuracy. After Klaproth's
Beitrage, no book can be named more highly deserving the study of the
analytical chemist than Stromeyer's Untersuchungen.

The first paper in this work contains the analysis of arragonite.
Chemists had not been able to discover any difference in the chemical
constitution of arragonite and calcareous spar, both being compounds of

  Lime             3·5
  Carbonic acid    2·75

Yet the minerals differ from each other in their hardness, specific
gravity, and in the shape of their crystals. Many attempts had been
made to account for this difference in characters between these two
minerals, but in vain. Mr. Holme showed that arragonite contained
about one per cent. of water, which is wanting in calcareous spar;
and that when arragonite is heated, it crumbles into powder, which is
not the case with calcareous spar. But it is not easy to conceive how
the addition of one per cent. of water should increase the specific
gravity and the hardness, and quite alter the shape of the crystals
of calcareous spar. Stromeyer made a vast number of experiments
upon arragonite, with very great care, and the result was, that the
arragonite from Bastenes, near Dax, in the department of Landes, and
likewise that from Molina, in Arragon, was a compound of

  96  carbonate of lime
   4  carbonate of strontian.

This amounts to about thirty-five atoms of carbonate of lime, and
one atom of carbonate of strontian. Now as the hardness and specific
gravity of carbonate of strontian is greater than that of carbonate of
lime, we can see a reason why arragonite should be heavier and harder
than calcareous spar. More late researches upon different varieties
of arragonite enabled him to ascertain that this mineral exists with
different proportions of carbonate of strontian. Some varieties contain
only 2 per cent., some only 1 per cent., and some only 0·75, or even
0·5 per cent.; but he found no specimen among the great number which
he analyzed totally destitute of carbonate of strontian. It is true
that Vauquelin afterwards examined several varieties in which he
could detect no strontian whatever; but as Vauquelin's mineralogical
knowledge was very deficient, it comes to be a question, whether the
minerals analyzed by him were really arragonites, or only varieties of
calcareous spar.

To Professor Stromeyer we are likewise indebted for the discovery of
the new metal called _cadmium_; and the discovery does great credit
to his sagacity and analytical skill. He is inspector-general of the
apothecaries for the kingdom of Hanover. While discharging the duties
of his office at Hildesheim, in the year 1817, he found that the
carbonate of zinc had been substituted for the oxide of zinc, ordered
in the Hanoverian Pharmacopœia. This carbonate of zinc was manufactured
at Salzgitter. On inquiry he learned from Mr. Jost, who managed that
manufactory, that they had been obliged to substitute the carbonate
for the oxide of zinc, because the oxide had a yellow colour which
rendered it unsaleable. On examining this oxide, Stromeyer found
that it owed its yellow colour to the presence of a small quantity of
the oxide of a new metal, which he separated, reduced, and examined,
and to which he gave the name of _cadmium_, because it occurs usually
associated with zinc. The quantity of cadmium which he was able to
obtain from this oxide of zinc was but small. A fortunate circumstance,
however, supplied him with an additional quantity, and enabled him to
carry his examination of cadmium to a still greater length. During the
apothecaries' visitation in the state of Magdeburg, there was found,
in the possession of several apothecaries, a preparation of zinc
from Silesia, made in Hermann's laboratory at Schönebeck, which was
confiscated on the supposition that it contained arsenic, because its
solution gave a yellow precipitate with sulphuretted hydrogen, which
was considered as orpiment. This statement could not be indifferent
to Mr. Hermann, as it affected the credit of his manufactory;
especially as the medicinal counsellor, Roloff, who had assisted
at the visitation, had drawn up a statement of the circumstances
which occasioned the confiscation, and caused it to be published in
Hofeland's Medical Journal. He subjected the suspected oxide to a
careful examination; but he could not succeed in detecting any arsenic
in it. He then requested Roloff to repeat his experiments. This he
did; and now perceived that the precipitate, which he had taken for
orpiment, was not so in reality, but owed its existence to the presence
of another metallic oxide, different from arsenic and probably new.
Specimens of this oxide of zinc, and of the yellow precipitate, were
sent to Stromeyer for examination, who readily recognised the presence
of cadmium, and was able to extract from it a considerable quantity of
that metal.

It is now nine years since the first volume of the Untersuchungen was
published. All those who are interested in analytical chemistry are
anxious for the continuance of that admirable work. By this time he
must have collected ample materials for an additional volume; and it
could not but add considerably to a reputation already deservedly high.

There is no living chemist, to whom analytical chemistry lies under
greater obligations than to Berzelius, whether we consider the number
or the exactness of the analyses which he has made.

Jacob Berzelius was educated at Upsala, when Professor Afzelius,
a nephew of Bergman, filled the chemical chair, and Ekeberg was
_magister docens_ in chemistry. Afzelius began his chemical career with
considerable _éclat_, his paper on sulphate of barytes being possessed
of very considerable merit. But he is said to have soon lost his
health, and to have sunk, in consequence, into listless inactivity.

Andrew Gustavus Ekeberg was born in Stockholm, on the 16th of January,
1767. His father was a captain in the Swedish navy. He was educated at
Calmar; and in 1784 went to Upsala, where he devoted himself chiefly
to the study of mathematics. He took his degree in 1788, when he wrote
a thesis "De Oleis Seminum expressis." In 1789 he went to Berlin; and
on his return, in 1790, he gave a specimen of his poetical talents,
by publishing a poem entitled "Tal öfver Freden emellan Sverige och
Ryssland" (Discourse about the Peace between Sweden and Russia). After
this he turned his attention to chemistry; and in 1794 was made _chemiæ
docens_. In this situation he continued till 1813, when he died on
the 11th of February. He had been in such bad health for some time
before his death, as to be quite unable to discharge the duties of his
situation. He published but little, and that little consisted almost
entirely of chemical analyses.

His first attempt was on phosphate of lime; then he wrote a paper
on the analysis of the topaz, the object of which was to explain
Klaproth's method of dissolving hard stony bodies.

He made an analysis of gadolinite, and determined the chemical
properties of yttria. During these experiments he discovered the new
metal to which he gave the name of _tantalum_, and which Dr. Wollaston
afterwards showed to be the same with the _columbium_ of Mr. Hatchett.
He also published an analysis of the automalite, of an ore of titanium,
and of the mineral water of Medevi. In this last analysis he was
assisted by Berzelius, who was then quite unknown to the chemical world.

Berzelius has been much more industrious than his chemical
contemporaries at Upsala. His first publication was a work in two
volumes on animal chemistry, chiefly a compilation, with the exception
of his experiments on the analysis of blood, which constitute an
introduction to the second volume. This book was published in 1806
and 1808. In the year 1806 he and Hisinger began a periodical work,
entitled "Afhandlingar i Fysik, Kemi och Mineralogi," of which six
volumes in all were published, the last in 1818. In this work there
occur forty-seven papers by Berzelius, some of them of great length
and importance, which will be noticed afterwards; but by far the
greatest part of them consist of mineral analyses. We have the analysis
of cerium by Hisinger and Berzelius, together with an account of
the chemical characters of the two oxides of cerium. In the fourth
volume he gives us a new chemical arrangement of minerals, founded
on the supposition that they are all chemical compounds in definite
proportions. Mr. Smithson had thrown out the opinion that _silica_
is an acid: which opinion was taken up by Berzelius, who showed, by
decisive experiments, that it enters into definite combinations
with most of the bases. This happy idea enabled him to show, that
most of the stony minerals are definite compounds of silica, with
certain earths or metallic oxides. This system has undergone several
modifications since he first gave it to the world; and I think it
more than doubtful whether his last co but he has taken care to have
translations of them inserted into Poggensdorf's Annalen, and the
Annales de Chimie et de Physique.

In the Stockholm Memoirs, for 1819, we have his analysis of wavellite,
showing that this mineral is a hydrous phosphate of alumina. The
same analysis and discovery had been made by Fuchs, who published
his results in 1818; but probably Berzelius had not seen the paper;
at least he takes no notice of it. We have also in the same volume
his analysis of euclase, of silicate of zinc, and his paper on the
prussiates.

In the Memoirs for 1820 we have, besides three others, his paper on
the mode of analyzing the ores of nickel. In the Memoirs for 1821 we
have his paper on the alkaline sulphurets, and his analysis of achmite.
The specimen selected for this analysis was probably impure; for two
successive analyses of it, made in my laboratory by Captain Lehunt,
gave a considerable difference in the proportion of the constituents,
and a different formula for the composition than that resulting from
the constituents found by Berzelius.

In the Memoirs for 1822 we have his analysis of the mineral waters
of Carlsbad. In 1823 he published his experiments on uranium, which
were meant as a confirmation and extension of the examination of this
substance previously made by Arfvedson. In the same year appeared his
experiments on fluoric acid and its combinations, constituting one of
the most curious and important of all the numerous additions which
he has made to analytical chemistry. In 1824 we have his analysis of
phosphate of yttria, a mineral found in Norway; of polymignite, a
mineral from the neighbourhood of Christiania, where it occurs in the
zircon sienite, and remarkable for the great number of bases which it
contains united to titanic acid; namely, zirconia, oxide of iron,
lime, oxide of manganese, oxide of cerium, and yttria. We have also
his analysis of arseniate of iron, from Brazil and from Cornwall; and
of chabasite from Ferro. In this last analysis he mentions chabasites
from Scotland, containing soda instead of lime. The only chabasites in
Scotland, that I know of, occur in the neighbourhood of Glasgow; and
in none of these have I found any soda. But I have found soda instead
of lime in chabasites from the north of Ireland, always crystallized
in the form to which Hauy has given the name of _trirhomboidale_. I
think, therefore, that the chabasites analyzed by Arfvedson, to which
Berzelius refers, must have been from Ireland, and not from Scotland;
and I think it may be a question whether this form of crystal, if it
should always be found to contain soda instead of lime, ought not to
constitute a peculiar species.

In 1826 we have his very elaborate and valuable paper on sulphur salts.
In this paper he shows that sulphur is capable of combining with
bodies, in the same way as oxygen, and of converting the acidifiable
bases into acids, and the alkalifiable bases into alkalies. These
sulphur acids and alkalies unite with each other, and form a new class
of saline bodies, which may be distinguished by the name of _sulphur
salts_. This subject has been since carried a good deal further by
M. H. Rose, who has by means of it thrown much light on some mineral
species hitherto quite inexplicable. Thus, what is called _nickel
glance_, is a sulphur salt of nickel. The acid is a compound of sulphur
and arsenic, the base a compound of sulphur and nickel. Its composition
may be represented thus:

  1 atom disulphide of arsenic
  1 atom disulphide of nickel.

In like manner glance cobalt is

  1 atom disulphide of arsenic
  1 atom disulphide of nickel.

Zinkenite is composed of

  3 atoms sulphide of antimony
  1 atom sulphide of lead;

and jamesonite of

  2½ atoms sulphide of antimony
  1 atom sulphide of lead.

Feather ore of antimony, hitherto confounded with sulphuret of
antimony, is a compound of

  5 atoms sulphide of antimony
  3 atoms sulphide of lead.

Gray copper ore, which has hitherto appeared so difficult to be reduced
to any thing like regularity, is composed of

  1 atom sulphide of antimony or arsenic
  2 atoms sulphide of copper or silver.

Dark red silver ore is composed of

  1 atom sulphide of antimony
  1 atom sulphide of silver;

and light red silver ore of

  2 atoms sesquisulphide of arsenic
  3 atoms sulphide of silver.

These specimens show how much light the doctrine of sulphur salts has
thrown on the mineral kingdom.

In 1828 he published his experimental investigation of the characters
and compounds of palladium, rhodium, osmium, and iridium; and upon the
mode of analyzing the different ores of platinum.

One of the greatest improvements which Berzelius has introduced into
analytical chemistry, is his mode of separating those bodies which
become acid when united to oxygen, as sulphur, selenium, arsenic, &c.,
from those that become alkaline, as copper, lead, silver, &c. His
method is to put the alloy or ore to be analyzed into a glass tube,
and to pass over it a current of dry chlorine gas, while the powder in
the tube is heated by a lamp. The acidifiable bodies are volatile, and
pass over along the tube into a vessel of water placed to receive them,
while the alkalifiable bodies remain fixed in the tube. This mode of
analysis has been considerably improved by Rose, who availed himself of
it in his analysis of gray copper ore, and other similar compounds.

Analytical chemistry lies under obligations to Berzelius, not merely
for what he has done himself, but for what has been done by those
pupils who were educated in his laboratory. Bonsdorf, Nordenskiöld,
C. G. Gmelin, Rose, Wöhler, Arfvedson, have given us some of the
finest examples of analytical investigations with which the science is
furnished.

P. A. Von Bonsdorf was a professor of Abo, and after that university
was burnt down, he moved to the new locality in which it was planted by
the Russian government. His analysis of the minerals which crystallize
in the form of the amphibole, constitutes a model for the young
analysts to study, whether we consider the precision of the analyses,
or the methods by which the different constituents were separated and
estimated. His analysis of red silver ore first demonstrated that
the metals in it were not in the state of oxides. The nature of the
combination was first completely explained by Rose, after Berzelius's
paper on the sulphur salts had made its appearance. His paper on the
acid properties of several of the chlorides, has served considerably to
extend and to rectify the views first proposed by Berzelius respecting
the different classes of salts.

Nils Nordenskiöld is superintendent of the mines in Finland: his
"Bidrag till närmare kännedom af Finland's Mineralier och Geognosie"
was published in 1820. It contains a description and analysis of
fourteen species of Lapland minerals, several of them new, and all
of them interesting. The analyses were conducted in Berzelius's
laboratory, and are excellent. In 1827 he published a tabular view
of the mineral species, arranged chemically, in which he gives the
crystalline form, hardness, and specific gravity, together with the
chemical formulas for the composition.

C. G. Gmelin is professor of chemistry at Tubingen; he has devoted
the whole of his attention to chemical analysis, and has published a
great number of excellent ones, particularly in Schweigger's Journal.
His analysis of helvine, and of the tourmalin, may be specified as
particularly valuable. In this last mineral, he demonstrated the
presence of boracic acid. Leopold Gmelin, professor of chemistry at
Heidelberg, has also distinguished himself as an analytical chemist.
His System of Chemistry, which is at present publishing, promises to be
the best and most perfect which Germany has produced.

Henry Rose, of Berlin, is the son of that M. Rose who was educated by
Klaproth, and afterwards became the intimate friend and fellow-labourer
of that illustrious chemist. He has devoted himself to analytical
chemistry with indefatigable zeal, and has favoured us with a
prodigious number of new and admirably-conducted analyses. His
analyses of pyroxenes, of the ores of titanium, of gray copper ore,
of silver glance, of red silver ore, miargyrite, polybasite, &c., may
be mentioned as examples. In 1829 he published a volume on analytical
chemistry, which is by far the most complete and valuable work of the
kind that has hitherto appeared; and ought to be carefully studied by
all those who wish to make themselves masters of the difficult, but
necessary art of analyzing compound bodies.[6]

 [6] An excellent English translation of this book with several
 important additions by the author, has just been published by Mr.
 Griffin.

Wöhler is professor of chemistry in the Polytechnic School of Berlin;
he does not appear to have turned his attention to analytical
chemistry, but rather towards extending our knowledge of the compounds
which the different simple bodies are capable of forming with each
other. His discovery of cyanic acid may be mentioned as a specimen. He
is active and young; much, therefore, may be expected from him.

Augustus Arfvedson has distinguished himself by the discovery of the
new fixed alkali, lithia, in petalite and spodumene. It has been lately
ascertained at Moscow, by M. R. Hermann, and the experiments have been
repeated and confirmed by Berzelius, that lithia is a much lighter
substance than it was found to be by Arfvedson, its atomic weight being
only 1·75. We have from Arfvedson an important set of experiments on
uranium and its oxides, and on the action of hydrogen on the metallic
sulphurets. He has likewise analyzed a considerable number of minerals
with great care; but of late years he seems to have lost his activity.
His analysis of chrysoberyl does not possess the accuracy of the rest:
by some inadvertence, he has taken a compound of glucina and alumina
for silica.

I ought to have included Walmstedt and Trollé-Wachmeister among
the Swedish chemists who have contributed important papers towards
the progress of analytical chemistry, the memoir of the former on
chrysolite, and of the latter on the garnets, being peculiarly
valuable. But it would extend this work to an almost interminable
length, if I were to particularize every meritorious experimenter. This
must plead my excuse for having omitted the names of Bucholz, Gehlen,
Fuchs, Dumesnil, Dobereiner, Kupfer, and various other meritorious
chemists who have contributed so much to the perfecting of the
chemical analysis of the mineral kingdom. But it would be unpardonable
to leave out the name of M. Mitcherlich, professor of chemistry in
Berlin, and successor of Klaproth, who was also a pupil of Berzelius.
He has opened a new branch of chemistry to our consideration. His
papers on isomorphous bodies, on the crystalline forms of various sets
of salts, on the artificial formation of various minerals, do him
immortal honour, and will hand him down to posterity as a fit successor
of his illustrious predecessors in the chemical chair of Berlin--a city
in which an uninterrupted series of first-rate chemists have followed
each other for more than a century; and where, thanks to the fostering
care of the Prussian government, the number was never greater than at
the present moment.

The most eminent analytical chemists at present in France are, Laugier,
a nephew and successor of Fourcroy, as professor of chemistry in the
Jardin du Roi, and Berthier, who has long had the superintendence of
the laboratory of the School of Mines. Laugier has not published many
analyses to the world, but those with which he has favoured us appear
to have been made with great care, and are in general very accurate.
Berthier is a much more active man; and has not merely given us many
analyses, but has made various important improvements in the analytical
processes. His mode of separating arsenic acid, and determining its
weight, is now generally followed; and I can state from experience
that his method of fusing minerals with oxide of lead, when the object
is to detect an alkali, is both accurate and easy. Berthier is young,
and active, and zealous; we may therefore expect a great deal from him
hereafter.

The chemists in great Britain have never hitherto distinguished
themselves much in analytical chemistry. This I conceive is owing
to the mode of education which has been hitherto unhappily followed.
Till within these very few years, practical chemistry has been
nowhere taught. The consequence has been, that every chemist must
discover processes for himself; and a long time elapses before he
acquires the requisite dexterity and skill. About the beginning of the
present century, Dr. Kennedy, of Edinburgh, was an enthusiastic and
dexterous analyst; but unfortunately he was lost to the science by a
premature death, after giving a very few, but these masterly, analyses
to the public. About the same time, Charles Hatchett, Esq., was an
active chemist, and published not a few very excellent analyses; but
unfortunately this most amiable and accomplished man has been lost
to science for more than a quarter of a century; the baneful effects
of wealth, and the cares of a lucrative and extensive business,
having completely weaned him from scientific pursuits. Mr. Gregor,
of Cornwall, was an accurate man, and attended only to analytical
chemistry: his analyses were not numerous, but they were in general
excellent. Unfortunately the science was deprived of his services by
a premature death. The same observation applies equally to Mr. Edward
Howard, whose analyses of meteoric stones form an era in this branch of
chemistry. He was not only a skilful chemist, but was possessed of a
persevering industry which peculiarly fitted him for making a figure as
a practical chemist. Of modern British analytical chemists, undoubtedly
the first is Mr. Richard Philips; to whom we are indebted for not
a few analyses, conducted with great chemical skill, and performed
with great accuracy. Unfortunately, of late years he has done little,
having been withdrawn from science by the necessity of providing for
a large family, which can hardly be done, in this country, except
by turning one's attention to trade or manufactures. The same remark
applies to Dr. Henry, who has contributed so much to our knowledge of
gaseous bodies, and whose analytical skill, had it been wholly devoted
to scientific investigations, would have raised his reputation, as a
discoverer, much higher than it has attained; although the celebrity
of Dr. Henry, even under the disadvantages of being a manufacturing
chemist, is deservedly very high. Of the young chemists who have but
recently started in the path of analytical investigation, we expect the
most from Dr. Turner, of the London University. His analyses of the
ores of manganese are admirable specimens of skill and accuracy, and
have completely elucidated a branch of mineralogy which, before his
experiments, and the descriptions of Haidinger appeared, was buried in
impenetrable darkness.

No man that Great Britain has produced was better fitted to have
figured as an analytical chemist, both by his uncommon chemical skill,
and the powers of his mind, which were of the highest order, than
Mr. Smithson Tennant, had he not been in some measure prevented by a
delicate frame of body, which produced in him a state of indolence
somewhat similar to that of Dr. Black. His discovery of osmium and
iridium, and his analysis of emery and magnesian limestone, may
be mentioned as proofs of what he could have accomplished had his
health allowed him a greater degree of exertion. His experiments on
the diamond first demonstrated that it was composed of pure carbon;
while his discovery of phosphuret of lime has furnished lecturers
on chemistry with one of the most brilliant and beautiful of those
exhibitions which they are in the habit of making to attract the
attention of their students.

Smithson Tennant was the only child of the Rev. Calvert Tennant,
youngest son of a respectable family in Wensleydale, near Richmond, in
Yorkshire, and vicar of Selby in that county. He was born on the 30th
of November, 1761: he had the misfortune to lose his father when he was
only nine years of age; and before he attained the age of manhood he
was deprived likewise of his mother, by a very unfortunate accident:
she was thrown from her horse while riding with her son, and killed on
the spot. His education, after his father's death, was irregular, and
apparently neglected; he was sent successively to different schools in
Yorkshire, at Scorton, Tadcaster, and Beverley. He gave many proofs
while young of a particular turn for chemistry and natural philosophy,
both by reading all books of that description which fell in his way,
and by making various little experiments which the perusal of these
books suggested. His first experiment was made at nine years of age,
when he prepared a quantity of gunpowder for fireworks, according to
directions contained in some scientific book to which he had access.

In the choice of a profession, his attention was naturally directed
towards medicine, as being more nearly allied to his philosophical
pursuits. He went accordingly to Edinburgh, about the year 1781, where
he laid the foundation of his chemical knowledge under Dr. Black. In
1782 he was entered a member of Christ's College, Cambridge, where he
began, from that time, to reside. He was first entered as a pensioner;
but disliking the ordinary discipline and routine of an academical
life, he obtained an exemption from those restraints, by becoming a
fellow commoner. During his residence at Cambridge his chief attention
was bestowed on chemistry and botany; though he made himself also
acquainted with the elementary parts of mathematics, and had mastered
the most important parts of Newton's Principia.

In 1784 he travelled into Denmark and Sweden, chiefly with the view of
becoming personally acquainted with Scheele, for whom he had imbibed
a high admiration. He was much gratified by what he saw of this
extraordinary man, and was particularly struck with the simplicity of
the apparatus with which his great experiments had been performed. On
his return to England he took great pleasure in showing his friends at
Cambridge various mineralogical specimens, which had been presented to
him by Scheele, and in exhibiting several interesting experiments which
he had learned from that great chemist. A year or two afterwards he
went to France, to become personally acquainted with the most eminent
of the French chemists. Thence he went to Holland and the Netherlands,
at that time in a state of insurrection against Joseph II.

In 1786 he left Christ's College along with Professor Hermann, and
removed with him to Emmanuel College. In 1788 he took his first degree
as bachelor of physic, and soon after quitted Cambridge and came to
reside in London. In 1791 he made his celebrated analysis of carbonic
acid, which fully confirmed the opinions previously stated by Lavoisier
respecting the constituents of this substance. His mode was to pass
phosphorus through red-hot carbonate of lime. The phosphorus was
acidified, and charcoal deposited. It was during these experiments that
he discovered phosphuret of lime.

In 1792 he again visited Paris; but, from circumstances, being afraid
of a convulsion, he was fortunate enough to leave that city the day
before the memorable 10th of August. He travelled through Italy, and
then passed through part of Germany. On his return to Paris, in
the beginning of 1793, he was deeply impressed with the gloom and
desolation arising from the system of terror then beginning to prevail
in that capital. On calling at the house of M. Delametherie, of whose
simplicity and moderation he had a high opinion, he found the doors
and windows closed, as if the owner were absent. Being at length
admitted, he found his friend sitting in a back room, by candle-light,
with the shutters closed in the middle of the day. On his departure,
after a hurried and anxious conversation, his friend conjured him not
to come again, as the knowledge of his being there might be attended
with serious consequences to them both. To the honour of Delametherie,
it deserves to be stated, that through all the inquisitions of the
revolution, he preserved for his friend property of considerable value,
which Mr. Tennant had intrusted to his care.

On his return from the continent, he took lodgings in the Temple,
where he continued to reside during the rest of his life. He still
continued the study of medicine, and attended the hospitals, but became
more indifferent about entering into practice. He took, however, a
doctor's degree at Cambridge in 1796; but resolved, as his fortune
was independent, to relinquish all idea of practice, as not likely
to contribute to his happiness. Exquisite sensibility was a striking
feature in his character, and it would, as he very properly conceived,
have made him peculiarly unfit for the exercise of the medical
profession. It may be worth while to relate an example of his practical
benevolence which happened about this time.

He had a steward in the country, in whom he had long placed implicit
confidence, and who was considerably indebted to him. In consequence
of this man's becoming embarrassed in his circumstances, Mr. Tennant
went into the country to examine his accounts. A time and place were
appointed for him to produce his books, and show the extent of the
deficiency; but the unfortunate steward felt himself unequal to the
task of such an explanation, and in a fit of despair put an end to
his existence. Touched by this melancholy event, Mr. Tennant used his
utmost exertions for the relief and protection of the family whom
he had left, and not only forgave them the debt, but afforded them
pecuniary assistance, and continued ever afterwards to be their friend
and benefactor.

During the year 1796 he made his experiments to prove that the diamond
is pure carbon. His method was to heat it in a gold tube, with
saltpetre. The diamond was converted into carbonic acid gas, which
combined with the potash from the saltpetre, and by the evolution of
which the quantity of carbon, in a given weight of diamond, might be
estimated. A characteristic trait of Mr. Tennant occurred during the
course of this experiment, which I relate on the authority of Dr.
Wollaston, who was present as an assistant, and who related the fact to
me. Mr. Tennant was in the habit of taking a ride on horseback every
day at a certain hour. The tube containing the diamond and saltpetre
were actually heating, and the experiment considerably advanced, when,
suddenly recollecting that his hour for riding was come, he left the
completion of the process to Dr. Wollaston, and went out as usual to
take his ride.

In the year 1797, in consequence of a visit to a friend in
Lincolnshire, where he witnessed the activity with which improvements
in farming operations were at that time going on, he was induced to
purchase some land in that country, in order to commence farming
operations. In 1799 he bought a considerable tract of waste land in
Somersetshire, near the village of Cheddar, where he built a small
house, in which, during the remainder of his life, he was in the habit
of spending some months every summer, besides occasional visits at
other times of the year. These farming speculations, as might have
been anticipated from the indolent and careless habits of Mr. Tennant,
were not very successful. Yet it appears from the papers which he left
behind him, that he paid considerable attention to agriculture, that he
had read the best books on the subject, and collected many facts on it
during his different journeys through various parts of England. In the
course of these inquiries he had discovered that there were two kinds
of limestone known in the midland counties of England, one of which
yielded a lime injurious to vegetation. He showed, in 1799, that the
presence of carbonate of magnesia is the cause of the bad qualities of
this latter kind of limestone. He found that the magnesian limestone
forms an extensive stratum in the midland counties, and that it occurs
also in primitive districts under the name of dolomite.

He infers from the slow solubility of this limestone in acids, that
it is a double salt composed of carbonate of lime and carbonate of
magnesia in chemical combination. He found that grain would scarcely
germinate, and that it soon perished in moistened carbonate of
magnesia: hence he concluded that magnesia is really injurious to
vegetation. Upon this principle he accounted for the injurious effects
of the magnesian limestone when employed as a manure.

In 1802 he showed that emery is merely a variety of corundum, or of the
precious stone known by the name of sapphire.

During the same year, while endeavouring to make an alloy of lead
with the powder which remains after treating crude platinum with
aqua regia, he observed remarkable properties in this powder, and
found that it contained a new metal. While he was engaged in the
investigation, Descotils had turned his attention to the same powder,
and had discovered that it contained a metal which gives a red colour
to the ammoniacal precipitate of platinum. Soon after, Vauquelin,
having treated the powder with alkali, obtained a volatile metallic
oxide, which he considered as the same metal that had been observed by
Descotils. In 1804 Mr. Tennant showed that this powder contains two new
metals, to which he gave the name of _osmium_ and _iridium_.

Mr. Tennant's health, by this time, had become delicate, and he seldom
went to bed without a certain quantity of fever, which often obliged
him to get up during the night and expose himself to the cold air. To
keep himself in any degree in health, he found it necessary to take a
great deal of exercise on horseback. He was always an awkward and a bad
horseman, so that those rides were sometimes a little hazardous; and
I have more than once heard him say, that a fall from his horse would
some day prove fatal to him. In 1809 he was thrown from his horse near
Brighton, and had his collar-bone broken.

In the year 1812 he was prevailed upon to deliver a few lectures on
the principles of mineralogy, to a number of his friends, among whom
were many ladies, and a considerable number of men of science and
information. These lectures were completely successful, and raised his
reputation very much among his friends as a lecturer. He particularly
excelled in the investigation of minerals by the blowpipe; and I have
heard him repeatedly say, that he was indebted for the first knowledge
of the mode of using that valuable instrument to Assessor Gahn Fahlun.

In 1813, a vacancy occurring in the chemical professorship at
Cambridge, he was solicited to become a candidate. His friends exerted
themselves in his favour with unexampled energy; and all opposition
being withdrawn, he was elected professor in May, 1813.

After the general pacification in 1814 he went to France, and repaired
to the southern provinces of that kingdom. He visited Lyons, Nismes,
Avignon, Marseilles, and Montpellier. He returned to Paris in November,
much gratified by his southern tour. He was to have returned to
England about the latter end of the year; but he continued to linger
on till the February following. On the 15th of that month he went to
Calais; but the wind blew directly into Calais harbour, and continued
unfavourable for several days. After waiting till the 20th he went to
Boulogne, in order to take the chance of a better passage from that
port. He embarked on board a vessel on the 22d, but the wind was still
adverse, and blew so violently that the vessel was obliged to put
back. When Mr. Tennant came ashore, he said that "it was in vain to
struggle with the elements, and that he was not yet tired of life."
It was determined, in case the wind should abate, to make another
trial in the evening. During the interval Mr. Tennant proposed to his
fellow-traveller, Baron Bulow, that they should hire horses and take
a ride. They rode at first along the sea-side; but, on Mr. Tennant's
suggestion, they went afterwards to Bonaparte's pillar, which stands on
an eminence about a league from the sea-shore, and which, having been
to see it the day before, he was desirous of showing to Baron Bulow.
On their return from thence they deviated a little from the road, in
order to look at a small fort near the pillar, the entrance to which
was over a fosse twenty feet deep. On the side towards them, there
was a standing bridge for some way, till it joined a drawbridge, which
turned on a pivot. The end next the fort rested on the ground. On the
side next to them it was usually fastened by a bolt; but the bolt had
been stolen about a fortnight before, and was not replaced. As the
bridge was too narrow for them to go abreast, the baron said he would
go first, and attempted to ride over it; but perceiving that it was
beginning to sink, he made an effort to pass the centre, and called out
to warn his companion of his danger; but it was too late: they were
both precipitated into the trench. The baron, though much stunned,
fortunately escaped without any serious hurt; but on recovering his
senses, and looking round for Mr. Tennant, he found him lying under his
horse nearly lifeless. He was taken, however, to the Civil Hospital,
as the nearest place ready to receive him. After a short interval, he
seemed in some slight degree to recover his senses, and made an effort
to speak, but without effect, and died within the hour. His remains
were interred a few days after in the public cemetery at Boulogne,
being attended to the grave by most of the English residents.

There is another branch of investigation intimately connected with
analytical chemistry, the improvements in which have been attended
with great advantage, both to mineralogists and chemists. I mean the
use of the blowpipe, to make a kind of miniature analysis of minerals
in the dry way; so far, at least, as to determine the nature of the
constituents of the mineral under examination. This is attended with
many advantages, as a preliminary to a rigid analysis by solution. By
informing us of the nature of the constituents, it enables us to form
a plan of the analysis beforehand, which, in many cases, saves the
trouble and the tediousness of two separate analytical investigations;
for when we set about analyzing a mineral, of the nature of which we
are entirely ignorant, two separate sets of experiments are in most
cases indispensable. We must examine the mineral, in the first place,
to determine the nature of its constituents. These being known, we
can form a plan of an analysis, by means of which we can separate and
estimate in succession the amount of each constituent of the mineral.
Now a judicious use of the blowpipe often enables us to determine the
nature of the constituents in a few minutes, and thus saves the trouble
of the preliminary analysis.

The blowpipe is a tube employed by goldsmiths in soldering. By means
of it, they force the flame of a candle or lamp against any particular
point which they wish to heat. This enables them to solder trinkets
of various kinds, without affecting any other part except the portion
which is required to be heated. Cronstedt and Engestroem first thought
of applying this little instrument to the examination of minerals. A
small fragment of the mineral to be examined, not nearly so large as
the head of a small pin, was put upon a piece of charcoal, and the
flame of a candle was made to play upon it by means of a blowpipe, so
as to raise it to a white heat. They observed whether it decrepitated,
or was dissipated, or melted; and whatever the effect produced was,
they were enabled from it to draw consequences respecting the nature of
the mineral under examination.

The importance of this instrument struck Bergman, and induced him
to wish for a complete examination of the action of the heat of the
blowpipe upon all different minerals, either tried _per se_ upon
charcoal, or mixed with various fluxes; for three different substances
had been chosen as fluxes, namely, _carbonate of soda_, _borax_, and
_biphosphate of soda_; or, at least, what was in fact an equivalent
for this last substance, _ammonio-phosphate of soda_, or _microcosmic
salt_, at that time extracted from urine. This salt is a compound
of one integrant particle of phosphate of soda, and one integrant
particle of phosphate of ammonia. When heated before the blowpipe it
fuses, and the water of crystallization, together with the ammonia, are
gradually dissipated, so that at last nothing remains but biphosphate
of soda. These fluxes have been found to act with considerable energy
on most minerals. The carbonate of soda readily fuses with those that
contain much silica, while the borax and biphosphate of soda act most
powerfully on the bases, not sensibly affecting the silica, which
remains unaltered in the fused bead. A mixture of borax and carbonate
of soda upon charcoal in general enables us to reduce the metallic
oxides to the state of metals, provided we understand the way of
applying the flame properly. Bergman employed Gahn, who was at that
time his pupil, and whose skill he was well acquainted with, to make
the requisite experiments. The result of these experiments was drawn
up into a paper, which Bergman sent to Baron Born in 1777, and they
were published by him at Vienna in 1779. This valuable publication
threw a new light upon the application of the blowpipe to the assaying
of minerals; and for every thing new which it contained Bergman was
indebted to Gahn, who had made the experiments.

John Gottlieb Gahn, the intimate friend of Bergman and of Scheele,
was one of the best-informed men, and one whose manners were the most
simple, unaffected, and pleasing, of all the men of science with whom I
ever came in contact. I spent a few days with him at Fahlun, in 1812,
and they were some of the most delightful days that I ever passed in my
life. His fund of information was inexhaustible, and was only excelled
by the charming simplicity of his manners, and by the benevolence and
goodness of heart which beamed in his countenance. He was born on the
17th of August, 1745, at the Woxna iron-works, in South Helsingland,
where his father, Hans Jacob Gahn, was treasurer to the government
of Stora Kopperberg. His grandfather, or great-grandfather, he told
me, had emigrated from Scotland; and he mentioned several families in
Scotland to which he was related. After completing his school education
at Westeräs, he went, in the year 1760, to the University of Upsala.
He had already shown a decided bias towards the study of chemistry,
mineralogy, and natural philosophy; and, like most men of science in
Sweden, where philosophical instrument-makers are scarcely to be found,
he had accustomed himself to handle the different tools, and to supply
himself in that manner with all the different pieces of apparatus which
he required for his investigations. He seems to have spent nearly
ten years at Upsala, during which time he acquired a very profound
knowledge in chemistry, and made various important discoveries, which
his modesty or his indifference to fame made him allow others to pass
as their own. The discovery of the rhomboidal nucleus of carbonate of
lime in a six-sided prism of that mineral, which he let fall, and which
was accidentally broken, constitutes the foundation of Hauy's system of
crystallization. He communicated the fact to Bergman, who published it
as his own in the second volume of his Opuscula, without any mention of
Gahn's name.

The earth of bones had been considered as a peculiar simple earth; but
Gahn ascertained, by analysis, that it was a compound of phosphoric
acid and lime; and this discovery he communicated to Scheele, who,
in his paper on fluor spar, published in 1771, observed, in the
seventeenth section, in which he is describing the effect of phosphoric
acid on fluor spar, "It has lately been discovered that the earth of
bones, or of horns, is calcareous earth combined with phosphoric acid."
In consequence of this remark, in which the name of Gahn does not
appear, it was long supposed that Scheele, and not Gahn, was the author
of this important discovery.

It was during this period that he demonstrated the metallic nature of
manganese, and examined the properties of the metal. This discovery was
announced as his, at the time, by Bergman, and was almost the only one
of the immense number of new facts which he had ascertained that was
publicly known to be his.

On the death of his father he was left in rather narrow circumstances,
which obliged him to turn his immediate attention to mining and
metallurgy. To acquire a practical knowledge of mining he associated
with the common miners, and continued to work like them till he had
acquired all the practical dexterity and knowledge which actual labour
could give. In 1770 he was commissioned by the College of Mines to
institute a course of experiments, with a view to improve the method of
smelting copper, at Fahlun. The consequence of this investigation was a
complete regeneration of the whole system, so as to save a great deal
both of time and fuel.

Sometime after, he became a partner in some extensive works at Stora
Kopperberg, where he settled as a superintendent. From 1770, when he
first settled at Fahlun, down to 1785, he took a deep interest in the
improvement of the chemical works in that place and neighbourhood. He
established manufactories of sulphur, sulphuric acid, and red ochre.

In 1780 the Royal College of Mines, as a testimony of their sense of
the value of Gahn's improvements, presented him with a gold medal of
merit. In 1782 he received a royal patent as mining master. In 1784 he
was appointed assessor in the Royal College of Mines, in which capacity
he officiated as often as his other vocations permitted him to reside
in Stockholm. The same year he married Anna Maria Bergstrom, with whom
he enjoyed for thirty-one years a life of uninterrupted happiness. By
his wife he had a son and two daughters.

In the year 1773 he had been elected chemical stipendiary to the Royal
College of Mines, and he continued to hold this appointment till the
year 1814. During the whole of this period the solution of almost
every difficult problem remitted to the college devolved upon him. In
1795 he was chosen a member of the committee for directing the general
affairs of the kingdom. In 1810 he was made one of the committee for
the general maintenance of the poor. In 1812 he was elected an active
associate of the Royal Academy for Agriculture; and in 1816 he became a
member of the committee for organizing the plan of a Mining Institute.
In 1818 he was chosen a member of the committee of the Mint; but from
this situation he was shortly after, at his own request, permitted to
withdraw.

His wife died in 1815, and from that period his health, which had never
been robust, visibly declined. Nature occasionally made an effort to
shake off the disease; but it constantly returned with increasing
strength, until, in the autumn of 1818, the decay became more rapid in
its progress, and more decided in its character. He became gradually
weaker, and on the 8th of December, 1818, died without a struggle, and
seemingly without pain.

Ever after the experiments on the blowpipe which Gahn performed at
the request of Bergman, his attention had been turned to that piece
of apparatus; and during the course of a long life he had introduced
so many improvements, that he was enabled, by means of the blowpipe,
to determine in a few minutes the constituents of almost any mineral.
He had gone over almost all the mineral kingdom, and determined the
behaviour of almost every mineral before the blowpipe, both by itself
and when mixed with the different fluxes and reagents which he had
invented for the purpose of detecting the different constituents; but,
from his characteristic unwillingness to commit his observations and
experiments to writing, or to draw them up into a regular memoir, had
not Berzelius offered himself as an assistant, they would probably
have been lost. By his means a short treatise on the blowpipe, with
minute directions how to use the different contrivances which he had
invented, was drawn up and inserted in the second volume of Berzelius's
Chemistry. Berzelius and he afterwards examined all the minerals
known, or at least which they could procure, before the blowpipe;
and the result of the whole constituted the materials of Berzelius's
treatise on the blowpipe, which has been translated into German,
French, and English. It may be considered as containing the sum of
all the improvements which Gahn had made on the use of the blowpipe,
together with all the facts that he had collected respecting the
phenomena exhibited by minerals before the blowpipe. It constitutes an
exceedingly useful and valuable book, and ought to make a part of the
library of every analytical chemist.

Dr. Wollaston had paid as much attention to the blowpipe as Gahn, and
had introduced so many improvements into its use, that he was able,
by means of it, to determine the nature of the constituents of any
mineral in the course of a few minutes. He was fond of such analytical
experiments, and was generally applied to by every person who thought
himself possessed of a new mineral, in order to be enabled to state
what its constituents were. The London mineralogists if the race be not
extinct, must sorely feel the want of the man to whom they were in the
habit of applying on all occasions, and to whom they never applied in
vain.

Dr. William Hyde Wollaston, was the son of the Reverend Dr. Wollaston,
a clergyman of some rank in the church of England, and possessed of a
competent fortune. He was a man of abilities, and rather eminent as an
astronomer. His grandfather was the celebrated author of the Religion
of Nature delineated. Dr. William Hyde Wollaston was born about the
year 1767, and was one of fifteen children, who all reached the age of
manhood. His constitution was naturally feeble; but by leading a life
of the strictest sobriety and abstemiousness he kept himself in a state
fit for mental exertion. He was educated at Cambridge, where he was at
one time a fellow. After studying medicine by attending the hospitals
and lectures in London, and taking his degree of doctor at Cambridge,
he settled at Bury St. Edmund's, where he practised as a physician
for some years. He then went to London, became a fellow of the Royal
College of Physicians, and commenced practitioner in the metropolis. A
vacancy occurring in St. George's Hospital, he offered himself for the
place of physician to that institution; but another individual, whom he
considered his inferior in knowledge and science, having been preferred
before him, he threw up the profession of medicine altogether, and
devoted the rest of his life to scientific pursuits. His income, in
consequence of the large family of his father, was of necessity small.
In order to improve it he turned his thoughts to the manufacture of
platinum, in which he succeeded so well, that he must have, by means
of it, realized considerable sums. It was he who first succeeded in
reducing it into ingots in a state of purity and fit for every kind of
use: it was employed, in consequence, for making vessels for chemical
purposes; and it is to its introduction that we are to ascribe the
present accuracy of chemical investigations. It has been gradually
introduced into the sulphuric acid manufactories, as a substitute for
glass retorts.

Dr. Wollaston had a particular turn for contriving pieces of apparatus
for scientific purposes. His reflecting goniometer was a most valuable
present to mineralogists, and it is by its means that crystallography
has acquired the great degree of perfection which it has recently
exhibited. He contrived a very simple apparatus for ascertaining the
power of various bodies to refract light. His camera lucida furnished
those who were ignorant of drawing with a convenient method of
delineating natural objects. His periscopic glasses must have been
found useful, for they sold rather extensively: and his sliding rule
for chemical equivalents furnished a ready method for calculating the
proportions of one substance necessary to decompose a given weight of
another.

Dr. Wollaston's knowledge was more varied, and his taste less exclusive
than any other philosopher of his time, except Mr. Cavendish: but
optics and chemistry are the two sciences which lie under the greatest
obligations to him. His first chemical paper on urinary calculi at once
added a vast deal to what had been previously known. He first pointed
out the constituents of the mulberry calculi, showing them to be
composed of oxalate of lime and animal matter. He first distinguished
the nature of the triple phosphates. It was he who first ascertained
the nature of the cystic oxides, and of the chalk-stones, which appear
occasionally in the joints of gouty patients. To him we owe the first
demonstration of the identity of galvanism and common electricity;
and the first explanation of the cause of the different phenomena
exhibited by galvanic and common electricity. To him we are indebted
for the discovery of palladium and rhodium, and the first account of
the properties and characters of these two metals. He first showed
that oxalic acid and potash unite in three different proportions,
constituting oxalate, binoxalate, and quadroxalate of potash. Many
other chemical facts, first ascertained by him, are to be found in the
numerous papers of his scattered over the last forty volumes of the
Philosophical Transactions: and perhaps not the least valuable of them
is his description of the mode of reducing platinum from the raw state,
and bringing it into the state of an ingot.

Dr. Wollaston died in the month of January, 1829, in consequence of
a tumour formed in the brain, near, if I remember right, the thalami
nervorum opticorum. There is reason to suspect that this tumour had
been some time in forming. He had, without exception, the sharpest
eye that I have ever seen: he could write with a diamond upon glass
in a character so small, that nothing could be distinguished by the
naked eye but a ragged line; yet when the letters were viewed through
a microscope, they were beautifully regular and quite legible. He
retained his senses to almost the last moment of his life: when he lay
apparently senseless, and his friends were anxiously solicitous whether
he still retained his understanding, he informed them, by writing, that
his senses were still perfectly entire. Few individuals ever enjoyed a
greater share of general respect and confidence, or had fewer enemies,
than Dr. Wollaston. He was at first shy and distant, and remarkably
circumspect, but he grew insensibly more and more agreeable as you got
better acquainted with him, till at last you formed for him the most
sincere friendship, and your acquaintance ended in the warmest and
closest attachment.




CHAPTER V.

OF ELECTRO-CHEMISTRY.


Electricity, like chemistry, is a modern science; for it can scarcely
claim an older origin than the termination of the first quarter of
the preceding century; and during the last half of that century, and
a small portion of the present, it participated with chemistry in the
zeal and activity with which it was cultivated by the philosophers
of Europe and America. For many years it was not suspected that any
connexion existed between chemistry and electricity; though some of the
meteorological phenomena, especially the production of clouds and the
formation of rain, which are obviously connected with chemistry, seem
likewise to claim some connexion with the agency of electricity.

The discovery of the intimate relation between chemistry and
electricity was one of the consequences of a controversy carried
on about the year 1790 between Galvani and Volta, two Italian
philosophers, whose discoveries will render their names immortal.
Galvani, who was a professor of anatomy, was engaged in speculations
respecting muscular motion. He was of opinion that a peculiar fluid
was secreted in the brain, which was sent along the nerves to all
the different parts of the body. This nervous fluid possessed many
characters analogous to those of electricity: the muscles were capable
of being charged with it somewhat like a Leyden phial; and it was by
the discharge of this accumulation, by the voluntary power of the
nerves, that muscular motion was produced. He accidently discovered,
that if the crural nerve going into the muscles of a frog, and the
crural muscles, be laid bare immediately after death, and a piece of
zinc be placed in contact with the nerve, and a piece of silver or
copper with the muscle; when these two pieces of metal are made to
touch each other, violent convulsions are produced in the muscle,
which cause the limb to move. He conceived that these convulsions were
produced by the discharge of the nervous energy from the muscles, in
consequence of the conducting power of the metals.

Volta, who repeated these experiments, explained them in a different
manner. According to him, the convulsions were produced by the passage
of a current of common electricity through the limb of the frog,
which was thrown into a state of convulsion merely in consequence of
its irritability. This irritability vanishes after the death of the
muscle; accordingly it is only while the principle of life remains that
the convulsions can be produced. Every metallic conductor, according
to him, possesses a certain electricity which is peculiar to it,
either positive or negative, though the quantity is so small, as to
be imperceptible, in the common state of the metal. But if a metal,
naturally positive, be placed in contact, while insulated, with a metal
naturally negative, the charge of electricity in both is increased by
induction, and becomes perceptible when the two metals are separated
and presented to a sufficiently delicate electrometer. Thus zinc is
naturally positive, and copper and silver naturally negative. If we
take two discs of copper and zinc, to the centre of each of which a
varnished glass handle is cemented, and after keeping them for a short
time in contact, separate them by the handles, and apply each to a
sufficiently delicate electrometer, we shall find that the zinc is
positive, and the silver or copper disc negative. When the silver and
copper are placed in contact while lying on the nerve and muscles of
the leg of a frog, the zinc becomes positive, and the silver negative,
by induction; but, as the animal substance is a conductor, this state
cannot continue: the two electricities pass through the conducting
muscles and nerve, and neutralize one another. And it is this current
which occasions the convulsions.

Such was Volta's simple explanation of the convulsions produced in
galvanic experiments in the limb of a frog. Galvani was far from
allowing the accuracy of it; and, in order to obviate the objection to
his reasoning advanced by Volta from the necessity of employing two
metals, he showed that the convulsions might, in certain cases, be
produced by one metal. Volta showed that a very small quantity of one
metal, either alloyed with, or merely in contact with another, were
capable of inducing the two electricities. But in order to prove in the
most unanswerable manner that the two electricities were induced when
two different metals were placed in contact, he contrived the following
piece of apparatus:

He procured a number (say 50) of pieces of zinc, about the size of
a crown-piece, and as many pieces of copper, and thirdly, the same
number of pieces of card of the same size. The cards were steeped in
a solution of salt, so as to be moist. He lays upon the table a piece
of zinc, places over it a piece of copper, and then a piece of moist
card. Over the card is placed a second piece of zinc, then a piece
of copper, then a piece of wet card. In this way all the pieces are
piled upon each other in exactly the same order, namely, zinc, copper,
card; zinc, copper, card; zinc, copper, card. So that the lowest plate
is zinc and the uppermost is copper (for the last wet card may be
omitted). In this way there are fifty pairs of zinc and copper plates
in contact, each separated by a piece of wet card, which is a conductor
of electricity. If you now moisten a finger of each hand with water,
and apply one wet finger to the lowest zinc plate, and the other to the
highest copper plate, the moment the fingers come in contact with the
plates an electric shock is felt, the intensity of which increases with
the number of pairs of plates in the pile. This is what is called the
Galvanic, or rather the Voltaic pile. It was made known to the public
in a paper by Volta, inserted in the Philosophical Transactions for
1800. This pile was gradually improved, by substituting troughs, first
of baked wood, and afterwards of porcelain, divided into as many cells
as there were pairs of plates. The size of the plates was increased;
they were made square, and instead of all being in contact, it was
found sufficient if they were soldered together by means of metallic
slips rising from one side of each square. The two plates thus soldered
were slipped over the diaphragm separating the contiguous cells, so
that the zinc plate was in one cell and the copper in the other. Care
was taken that the pairs were introduced all looking one way, so that
a copper plate had always a zinc plate immediately opposite to it.
The cells were filled with conducting liquid: brine, or a solution of
salt in vinegar, or dilute muriatic, sulphuric, or nitric acid, might
be employed; but dilute nitric acid was found to answer best, and the
energy of the battery is directly proportional to the strength of the
nitric acid employed.

Messrs. Nicholson and Carlisle were the first persons who repeated
Volta's experiments with this apparatus, which speedily drew the
attention of all Europe. They ascertained that the zinc end of the
pile was positive and the copper end negative. Happening to put a drop
of water on the uppermost plate, and to put into it the extremity
of a gold wire connected with the undermost plate, they observed an
extrication of air-bubbles from the wire. This led them to suspect that
the water was decomposed. To determine the point, they collected a
little of the gas extricated and found it hydrogen. They then attached
a gold wire to the zinc end of the pile, and another gold wire to the
copper end, and plunged the two wires into a glass of water, taking
care not to allow them to touch each other. Gas was extricated from
both wires. On collecting that from the wire attached to the zinc end,
it was found to be _oxygen gas_, while that from the copper end was
hydrogen gas. The volume of hydrogen gas extricated was just double
that of the oxygen gas; and the two gases being mixed, and an electric
spark passed through them, they burnt with an explosion, and were
completely converted into water. Thus it was demonstrated that water
was decomposed by the action of the pile, and that the oxygen was
extricated from the positive pile and the hydrogen from the negative.
This held when the communicating wires were gold or platinum; but
if they were of copper, silver, iron, lead, tin, or zinc, then only
hydrogen gas was extricated from the negative wire. The positive wire
extricated little or no gas; but it was rapidly oxidized. Thus the
connexion between chemical decompositions and electrical currents was
first established.

It was soon after observed by Henry, Haldane, Davy, and other
experimenters, that other chemical compounds were decomposed by the
electrical currents as well as water. Ammonia, for example, nitric
acid, and various salts, were decomposed by it. In the year 1803 an
important set of experiments was published by Berzelius and Hisinger.
They decomposed eleven different salts, by exposing them to the action
of a current of electricity. The salts were dissolved in water, and
iron or silver wires from the two poles of the pile were plunged into
the solution. In every one of these decompositions, the acid was
deposited round the positive wire, and the base of the salt round the
negative wire. When ammonia was decomposed by the action of galvanic
electricity, the azotic gas separated from the positive wire, and the
hydrogen gas from the negative.

But it was Davy that first completely elucidated the chemical
decompositions produced by galvanic electricity, who first explained
the laws by which these decompositions were regulated, and who employed
galvanism as an instrument for decomposing various compounds, which had
hitherto resisted all the efforts of chemists to reduce them to their
elements. These discoveries threw a blaze of light upon the obscurest
parts of chemistry, and secured for the author of them an immortal
reputation.

Humphry Davy, to whom these splendid discoveries were owing, was born
at Penzance, in Cornwall, in the year 1778. He displayed from his very
infancy a spirit of research, and a brilliancy of fancy, which augured,
even at that early period, what he was one day to be. When very
young, he was bound apprentice to an apothecary in his native town.
Even at that time, his scientific acquirements were so great, that
they drew the attention of Mr. Davis Gilbert, the late distinguished
president of the Royal Society. It was by his advice that he resolved
to devote himself to chemistry, as the pursuit best calculated to
procure him celebrity. About this time Mr. Gregory Watt, youngest son
of the celebrated improver of the steam-engine, happening to be at
Penzance, met with young Davy, and was delighted with the uncommon
knowledge which he displayed, at the brilliancy of his fancy, and
the great dexterity and ardour with which, under circumstances the
most unfavourable, he was prosecuting his scientific investigations.
These circumstances made an indelible impression on his mind, and led
him to recommend Davy as the best person to superintend the Bristol
Institution for trying the medicinal effects of the gases.

After the discovery of the different gases, and the investigation of
their properties by Dr. Priestley, it occurred to various individuals,
nearly about the same time, that the employment of certain gases, or
at least of mixtures of certain gases, with common air in respiration,
instead of common air, might be powerful means of curing diseases.
Dr. Beddoes, at that time professor of chemistry at Oxford, was one
of the keenest supporters of these opinions. Mr. Watt, of Birmingham,
and Mr. Wedgewood, entertained similar sentiments. About the beginning
of the present century, a sum of money was raised by subscription,
to put these opinions to the test of experiment; and, as Dr. Beddoes
had settled as a physician in Bristol, it was agreed upon that the
experimental investigation should take place at Bristol. But Dr.
Beddoes was not qualified to superintend an institution of the kind:
it was necessary to procure a young man of zeal and genius, who would
take such an interest in the investigation as would compensate for
the badness of the apparatus and the defects of the arrangements. The
greatest part of the money had been subscribed by Mr. Wedgewood and
Mr. Watt: their influence of course would be greatest in recommending
a proper superintendent. Gregory Watt thought of Mr. Davy, whom he
had lately been so highly pleased with, and recommended him with
much zeal to superintend the undertaking. This recommendation being
seconded by that of Mr. Davis Gilbert, who was so well acquainted
with the scientific acquirements and genius of Davy, proved
successful, and Davy accordingly got the appointment. At Bristol he
was employed about a year in investigating the effects of the gases
when employed in respiration. But he did not by any means confine
himself to this, which was the primary object of the institution;
but investigated the properties and determined the composition of
nitric acid, ammonia, protoxide of azote and deutoxide of azote.
The fruit of his investigations was published in 1800, in a volume
entitled, "Researches, Chemical and Philosophical; chiefly concerning
Nitrous Oxide, or Dephlogisticated Nitrous Air, and its Respiration."
This work gave him at once a high reputation as a chemist, and was
really a wonderful performance, when the circumstances under which
it was produced are taken into consideration. He had discovered the
intoxicating effects which protoxide of azote (nitrous oxide) produces
when breathed, and had tried their effects upon a great number of
individuals. This fortunate discovery perhaps contributed more to his
celebrity, and to his subsequent success, than all the sterling merit
of the rest of his researches--so great is the effect of display upon
the greater part of mankind.

A few years before, a philosophical institution had been established
in London, under the auspices of Count Rumford, which had received
the name of the Royal Institution. Lectures on chemistry and natural
philosophy were delivered in this institution; a laboratory was
provided, and a library established. The first professor appointed to
this institution, Dr. Garnet, had been induced, in consequence of some
disagreement between him and Count Rumford, to throw up his situation.
Many candidates started for it; but Davy, in consequence of the
celebrity which he had acquired by his researches, or perhaps by the
intoxicating effects of protoxide of azote, which he had discovered,
was, fortunately for the institution and for the reputation of England,
preferred to them all. He was appointed professor of chemistry, and Dr.
Thomas Young professor of natural philosophy, in the year 1801. Davy,
either from the more popular nature of his subject, or from his greater
oratorical powers, became at once a popular lecturer, and always
lectured to a crowded room; while Dr. Young, though both a profound and
clear lecturer, could scarcely command an audience of a dozen. It was
here that Davy laboured with unwearied industry during eleven years,
and acquired, by his discoveries the highest reputation of any chemist
in Europe.

In 1811 he was knighted, and soon after married Mrs. Apreece, a widow
lady, daughter of Mr. Ker, who had been secretary to Lord Rodney, and
had made a fortune in the West Indies. He was soon after created a
baronet. About this time he resigned his situation as professor of
chemistry in the Royal Institution, and went to the continent. He
remained for some years in France and Italy. In the year 1821, when Sir
Joseph Banks died, a very considerable number of the fellows offered
their votes to Dr. Wollaston; but he declined standing as a candidate
for the president's chair. Sir Humphry Davy, on the other hand, was
anxious to obtain that honourable situation, and was accordingly
elected president by a very great majority of votes on the 30th of
November, 1821. This honourable situation he filled about seven years;
but his health declining, he was induced to resign in 1828, and to go
to Italy. Here he continued till 1829, when feeling himself getting
worse, and wishing to draw his last breath in his own country, he began
to turn his way homewards; but at Geneva he felt himself so ill, that
he was unable to proceed further: here he took to his bed, and here he
died on the 29th of May, 1829.

It was his celebrated paper "On some chemical Agencies of Electricity,"
inserted in the Philosophical Transactions for 1807, that laid the
foundation of the high reputation which he so deservedly acquired. I
consider this paper not merely as the best of all his own productions,
but as the finest and completest specimen of inductive reasoning
which appeared during the age in which he lived. It had been already
observed, that when two platinum wires from the two poles of a galvanic
pile are plunged each into a vessel of water, and the two vessels
united by means of wet asbestos, or any other conducting substance,
an _acid_ appeared round the positive wire and an _alkali_ round the
negative wire. The alkali was said by some to be _soda_, by others
to be _ammonia_. The acid was variously stated to be _nitric acid_,
_muriatic acid_, or even _chlorine_. Davy demonstrated, by decisive
experiments, that in all cases the acid and alkali are derived from
the decomposition of some salt contained either in the water or in
the vessel containing the water. Most commonly the salt decomposed
is common salt, because it exists in water and in agate, basalt, and
various other stony bodies, which he employed as vessels. When the same
agate cup was used in successive experiments, the quantity of acid
and alkali evolved diminished each time, and at last no appreciable
quantity could be perceived. When glass vessels were used, soda was
disengaged at the expense of the glass, which was sensibly corroded.
When the water into which the wires were dipped was perfectly pure,
and when the vessel containing it was free from every trace of saline
matter, no acid or alkali made its appearance, and nothing was evolved
except the constituents of water, namely, oxygen and hydrogen; the
oxygen appearing round the positive wire, and the hydrogen round the
negative wire.

When a salt was put into the vessel in which the positive wire dipped,
the vessel into which the negative wire dipped being filled with
pure water, and the two vessels being united by means of a slip of
moistened asbestos, the acid of the salt made its appearance round the
positive wire, and the alkali round the negative wire, before it could
be detected in the intermediate space; but if an intermediate vessel,
containing a substance for which the alkali has a strong affinity, be
placed between these two vessels, the whole being united by means of
slips of asbestos, then great part, or even the whole of the alkali,
was stopped in this intermediate vessel. Thus, if the salt was nitrate
of barytes, and sulphuric acid was placed in the intermediate vessel,
much sulphate of barytes was deposited in the intermediate vessel, and
very little or even no barytes made its appearance round the negative
wire. Upon this subject a most minute, extensive, and satisfactory
series of experiments was made by Davy, leaving no doubt whatever of
the accuracy of the fact.

The conclusions which he drew from these experiments are, that all
substances which have a chemical affinity for each other, are in
different states of electricity, and that the degree of affinity is
proportional to the intensity of these opposite states. When such
a compound body is placed in contact with the poles of a galvanic
battery, the positive pole attracts the constituent, which is
negative, and repels the positive. The negative acts in the opposite
way, attracting the positive constituent and repelling the negative.
The more powerful the battery, the greater is the force of these
attractions and repulsions. We may, therefore, by increasing the
energy of a battery sufficiently, enable it to decompose any compound
whatever, the negative constituent being attracted by the positive
pole, and the positive constituent by the negative pole. Oxygen,
chlorine, bromine, iodine, cyanogen, and acids, are _negative_ bodies;
for they always appear round the _positive_ pole of the battery, and
are therefore attracted to it: while hydrogen, azote, carbon, selenium,
metals, alkalies, earths, and oxide bases, are deposited round the
negative pole, and consequently are _positive_.

According to this view of the subject, chemical affinity is merely
a case of the attractions exerted by bodies in different states of
electricity. Volta first broached the idea, that every body possesses
naturally a certain state of electricity. Davy went a step further,
and concluded, that the attractions which exist between the atoms of
different bodies are merely the consequence of these different states
of electricity. The proof of this opinion is founded on the fact, that
if we present to a compound, sufficiently strong electrical poles, it
will be separated into its constituents, and one of these constituents
will invariably make its way to the positive and the other to the
negative pole. Now bodies in a state of electrical excitement always
attract those that are in the opposite state.

If electricity be considered as consisting of two distinct fluids,
which attract each other with a force inversely, as the square of the
distance, while the particles of each fluid repel each other with a
force varying according to the same law, then we must conclude that
the atoms of each body are covered externally with a coating of some
one electric fluid to a greater or smaller extent. Oxygen and the
other supporters of combustion are covered with a coating of negative
electricity; while hydrogen, carbon, and the metals, are covered with
a coating of positive electricity. What is the cause of the adherence
of the electricity to these atoms we cannot explain. It is not owing to
an attraction similar to gravitation; for electricity never penetrates
into the interior of bodies, but spreads itself only on the surface,
and the quantity of it which can accumulate is not proportional to
the quantity of matter but to the extent of surface. But whatever be
the cause, the adhesion is strong, and seemingly cannot be overcome.
If we were to suppose an atom of any body, of oxygen for example, to
remain uncombined with any other body, but surrounded by electricity,
it is obvious that the coating of negative electricity on its surface
would be gradually neutralized by its attracting and combining with
positive electricity. But let us suppose an atom of oxygen and an atom
of hydrogen to be united together, it is obvious that the positive
electricity of the one atom would powerfully attract the negative
electricity of the other, and _vice versâ_. And if these respective
electricities cannot leave the atoms, the two atoms will remain firmly
united, and the opposite electrical intensities will in some measure
neutralize each other, and thus prevent them from being neutralized
by electricity from any other quarter. But a current of the opposite
electricities passing through such a compound, might neutralize the
electricity in each, and thus putting an end to their attractions,
occasion decomposition.

Such is a very imperfect outline of the electrical theory of affinity
first proposed by Davy to account for the decompositions produced by
electricity. It has been universally adopted by chemists; and some
progress has been made in explaining and accounting for the different
phenomena. It would be improper, in a work of this kind, to enter
further into the subject. Those who are interested in such discussions
will find a good deal of information in the first volume of Berzelius's
Treatise on Chemistry, in the introduction to the Traité de Chimie
appliqué aux Arts, by Dumas, or in the introduction to my System of
Chemistry, at present in the press.

Davy having thus got possession of an engine, by means of which the
compounds, whose constituents adhered to each other might be separated,
immediately applied it to the decomposition of potash and soda;
bodies which were admitted to be compounds, though all attempts to
analyze them had hitherto failed. His attempt was successful. When
a platinum wire from the negative pole of a strong battery in full
action was applied to a lump of potash, slightly moistened, and lying
on a platinum tray attached to the positive pole of the battery, small
globules of a white metal soon appeared at its extremity. This white
metal he speedily proved to be the basis of potash. He gave it the name
of _potassium_, and very soon proved, that potash is a compound of five
parts by weight of this metal and one part of oxygen. Potash, then,
is a metallic oxide. He proved soon after that soda is a compound of
oxygen and another white metal, to which he gave the name of _sodium_.
Lime is a compound of _calcium_ and oxygen, magnesia of _magnesium_ and
oxygen, barytes of _barium_ and oxygen, and strontian of _strontium_
and oxygen. In short, the fixed alkalies and alkaline earths, are
metallic oxides. When _lithia_ was afterwards discovered by Arfvedson,
Davy succeeded in decomposing it also by the galvanic battery, and
resolving it into oxygen and a white metal, to which the name of
_lithium_ was given.

Davy did not succeed so well in decomposing alumina, glucina, yttria,
and zirconia, by the galvanic battery: they were not sufficiently good
conductors of electricity; but nobody entertained any doubt that they
also were metallic oxides. They have been all at length decomposed, and
their bases obtained by the joint action of chlorine and potassium,
and it has been demonstrated, that they also are metallic oxides. Thus
it has been ascertained, in consequence of Davy's original discovery
of the powers of the galvanic battery, that all the bases formerly
distinguished into the four classes of alkalies, alkaline earths,
earths proper, and metallic oxides, belong in fact only to one class,
and are all metallic oxides.

Important as these discoveries are, and sufficient as they would
have been to immortalize the author of them, they are not the only
ones for which we are indebted to Sir Humphry Davy. His experiments
on _chlorine_ are not less interesting or less important in their
consequences. I have already mentioned in a former chapter, that
Berthollet made a set of experiments on chlorine, from which he had
drawn as a conclusion, that it is a compound of oxygen and muriatic
acid, in consequence of which it got the name of _oxymuriatic acid_.
This opinion of Berthollet had been universally adopted by chemists,
and admitted by them as a fundamental principle, till Gay-Lussac
and Thenard endeavoured, unsuccessfully, to decompose this gas, or
to resolve it into muriatic acid and chlorine. They showed, in the
clearest manner, that such a resolution was impossible, and that no
direct evidence could be adduced to prove that oxygen was one of its
constituents. The conclusion to which they came was, that muriatic acid
gas contained water as an essential constituent; and they succeeded by
this hypothesis in accounting for all the different phenomena which
they had observed. They even made an experiment to determine the
quantity of water thus combined. They passed muriatic acid through hot
litharge (protoxide of lead); muriate of lead was formed, and abundance
of water made its appearance and was collected. They did not attempt to
determine the proportions; but we can now easily calculate the quantity
of water which would be deposited when a given weight of muriatic acid
gas is absorbed by a given weight of litharge. Suppose we have fourteen
parts of oxide of lead: to convert it into muriate of lead, 4·625
parts (by weight) of muriatic acid would be necessary, and during the
formation of the muriate of lead there would be deposited 1·125 parts
of water. So that from this experiment it might be concluded, that
about one-fourth of the weight of muriatic acid gas is water.

The very curious and important facts respecting chlorine and muriatic
acid gas which they had ascertained, were made known by Gay-Lussac
and Thenard to the Institute, on the 27th of February, 1809, and an
abstract of them was published in the second volume of the Mémoires
d'Arcueil. There can be little doubt that it was in consequence of
these curious and important experiments of the French chemists that
Davy's attention was again turned to muriatic acid gas. He had already,
in 1808, shown that when potassium is heated in muriatic acid gas,
muriate of potash is formed, and a quantity of hydrogen gas evolved,
amounting to more than one-third of the muriatic acid gas employed,
and he had shown, that in no case can muriatic acid be obtained from
chlorine, unless water or its elements be present. This last conclusion
had been amply confirmed by the new investigations of Gay-Lussac and
Thenard. In 1810 Davy again resumed the examination of the subject, and
in July of that year read a paper to the Royal Society, to prove that
_chlorine_ is a simple substance, and that muriatic acid is a compound
of _chlorine_ and _hydrogen_.

This was introducing an alteration in chemical theory of the same
kind, and nearly as important, as was introduced by Lavoisier, with
respect to the action of oxygen in the processes of combustion and
calcination. It had been previously supposed that sulphur, phosphorus,
charcoal, and metals, were compounds; one of the constituents of which
was phlogiston, and the other the acids or oxides which remained after
the combustion or calcination had taken place. Lavoisier showed that
the sulphur, phosphorus, charcoal, and metals, were simple substances;
and that the acids or calces formed were compounds of these simple
bodies and oxygen. In like manner, Davy showed that chlorine, instead
of being a compound of muriatic acid and oxygen, was, in fact, a simple
substance, and muriatic acid a compound of chlorine and hydrogen.
This new doctrine immediately overturned the Lavoisierian hypothesis
respecting oxygen as the acidifying principle, and altered all the
previously received notions respecting the muriates. What had been
called _muriates_ were, in fact, combinations of chlorine with the
combustible or metal, and were analogous to oxides. Thus, when muriatic
acid gas was made to act upon hot litharge, a double decomposition
took place, the chlorine united to the lead, while the hydrogen of the
muriatic acid united with the oxygen of the litharge, and formed water.
Hence the reason of the appearance of water in this case; and hence it
was obvious that what had been called muriate of lead, was, in reality,
a compound of chlorine and metallic lead. It ought, therefore, to be
called, not muriate of lead, but chloride of lead.

It was not likely that this new opinion of Davy should be adopted by
chemists in general, without a struggle to support the old opinions.
But the feebleness of the controversy which ensued, affords a striking
proof how much chemistry had advanced since the days of Lavoisier, and
how free from prejudices chemists had become. One would have expected
that the French chemists would have made the greatest resistance to the
admission of these new opinions; because they had a direct tendency
to diminish the reputation of two of their most eminent chemists,
Lavoisier and Berthollet. But the fact was not so: the French chemists
showed a degree of candour and liberality which redounds highly to
their credit. Berthollet did not enter at all into the controversy.
Gay-Lussac and Thenard, in their Recherches Physico-chimiques,
published in 1811, state their reasons for preferring the old
hypothesis to the new, but with great modesty and fairness; and,
within less than a year after, they both adopted the opinion of Davy,
that chlorine is a simple substance, and muriatic acid a compound of
hydrogen and chlorine.

The only opponents to the new doctrine who appeared against it,
were Dr. John Murray, of Edinburgh, and Professor Berzelius, of
Stockholm. Dr. Murray was a man of excellent abilities, and a very
zealous cultivator of chemistry; but his health had been always very
delicate, which had prevented him from dedicating so much of his
time to experimenting as he otherwise would have been inclined to
do. The only experimental investigations into which he entered was
the analysis of some mineral waters. His powers of elocution were
great. He was, in consequence, a popular and very useful lecturer. He
published animadversions upon the new doctrine respecting _chlorine_,
in Nicholson's Journal; and his observations were answered by Dr. John
Davy.

Dr. John Davy was the brother of Sir Humphry, and had shown, by his
paper on fluoric acid and on the chlorides, that he possessed the same
dexterity and the same powers of inductive reasoning, which had given
so much celebrity to his brother. The controversy between him and Dr.
Murray was carried on for some time with much spirit and ingenuity
on both sides, and was productive of some advantage to the science
of chemistry, by the discovery of phosgene gas or chlorocarbonic
acid, which was made by Dr. Davy. It is needless to say to what
side the victory fell. The whole chemical world has for several
years unanimously adopted the theory of Davy; showing sufficiently
the opinion entertained respecting the arguments advanced by either
party. Berzelius supported the old opinion respecting the compound
nature of chlorine, in a paper which he published in the Annals of
Philosophy. No person thought it worth while to answer his arguments,
though Sir Humphry Davy made a few animadversions upon one or two of
his experiments. The discovery of iodine, which took place almost
immediately after, afforded so close an analogy with chlorine, and
the nature of the compounds which it forms was so obvious and so well
made out, that chemists were immediately satisfied; and they furnished
so satisfactory an answer to all the objections of Berzelius, that
I am not aware of any person, either in Great Britain or in France,
who adopted his opinions. I have not the same means of knowing the
impression which his paper made upon the chemists of Germany and
Sweden. Berzelius continued for several years a very zealous opponent
to the new doctrine, that chlorine is a simple substance. But he
became at last satisfied of the futility of his own objections, and
the inaccuracy of his reasoning. About the year 1820 he embraced the
opinion of Davy, and is now one of its most zealous defenders. Dr.
Murray has been dead for many years, and Berzelius has renounced his
notion, that muriatic acid is a compound of oxygen and an unknown
combustible basis. We may say then, I believe with justice, that at
present all the chemical world adopts the notion that chlorine is a
simple substance, and muriatic acid a compound of chlorine and hydrogen.

The recent discovery of bromine, by Balard, has added another strong
analogy in favour of Davy's theory; as has likewise the discovery by
Gay-Lussac respecting prussic acid. At present, then, (not reckoning
sulphuretted and telluretted hydrogen gas), we are acquainted with
four acids which contain no oxygen, but are compounds of hydrogen with
another negative body. These are

  Muriatic acid, composed of chlorine and hydrogen
  Hydriodic acid             iodine and hydrogen
  Hydrobromic acid           bromine and hydrogen
  Prussic acid               cyanogen and hydrogen.

So that even if we were to leave out of view the chlorine acids, the
sulphur acids, &c., no doubt can be entertained that many acids exist
which contain no oxygen. Acids are compounds of electro-negative bodies
and a base, and in them all the electro-negative electricity continues
to predominate.

Next to Sir Humphry Davy, the two chemists who have most advanced
electro-chemistry are Gay-Lussac and Thenard. About the year 1808,
when the attention of men of science was particularly drawn towards
the galvanic battery, in consequence of the splendid discoveries of
Sir Humphry Davy, Bonaparte, who was at that time Emperor of France,
consigned a sufficient sum of money to Count Cessac, governor of the
Polytechnic School, to construct a powerful galvanic battery; and
Gay-Lussac and Thenard were appointed to make the requisite experiments
with this battery. It was impossible that a better choice could have
been made. These gentlemen undertook a most elaborate and extensive
set of experiments, the result of which was published in 1811, in two
octavo volumes, under the title of "Recherches Physico-chimiques,
faites sur la Pile; sur la Preparation chimique et les Propriétés du
Potassium et du Sodium; sur la Décomposition de l'Acide boracique;
sur les Acides fluorique, muriatique, et muriatique oxygené; sur
l'Action chimique de la Lumière; sur l'Analyse vegetale et animale,
&c." It would be difficult to name any chemical book that contains a
greater number of new facts, or which contains so great a collection of
important information, or which has contributed more to the advancement
of chemical science.

The first part contains a very minute and interesting examination
of the galvanic battery, and upon what circumstances its energy
depends. They tried the effect of various liquid conductors, varied
the strength of the acids and of the saline solutions. This division
of their labours contains much valuable information for the practical
electro-chemist, though it would be inconsistent with the plan of this
work to enter into details.

The next division of the work relates to potassium. Davy had hitherto
produced that metal only in minute quantities by the action of the
galvanic battery upon potash. But Gay-Lussac and Thenard contrived
a process by which it can be prepared on a large scale by chemical
decomposition. Their method was, to put into a bent gun-barrel, well
coated externally with clay, and passed through a furnace, a quantity
of clean iron-filings. To one extremity of this barrel was fitted a
tube containing a quantity of caustic potash. This tube was either shut
at one end by a stopper, or by a glass tube luted to it, and plunged
under the surface of mercury. To the other extremity of the gun-barrel
was also luted a tube, which plunged into a vessel containing mercury.
Heat was applied to the gun-barrel till it was heated to whiteness;
then, by means of a choffer, the caustic potash was melted and made to
trickle slowly into the white-hot iron-filings. At this temperature the
potash undergoes decomposition, the iron uniting with its oxygen. The
potassium is disengaged, and being volatile is deposited at a distance
from the hot part of the tube, where it is collected after the process
is finished.

Being thus in possession, both of potassium and sodium in considerable
quantities, they were enabled to examine its properties more in detail
than Davy had done: but such was the care and industry with which
Davy's experiments had been made that very little remained to be
done. The specific gravity of the two metals was determined with more
precision than it was possible for Davy to do. They determined the
action of these metals on water, and measured the quantity of hydrogen
gas given out with more precision than Davy could. They discovered
also, by heating these metals in oxygen gas, that they were capable of
uniting with an additional dose of oxygen, and of forming peroxides of
potassium and sodium. These oxides have a yellow colour, and give out
the surplus oxygen, and are brought back to the state of potash and
soda when they are plunged into water. They exposed a great variety of
substances to the action of potassium, and brought to light a vast
number of curious and important facts, tending to throw new light on
the properties and characters of that curious metallic substance.

By heating together anhydrous boracic acid and potassium in a copper
tube, they succeeded in decomposing the acid, and in showing it to
be a compound of oxygen, and a black matter like charcoal, to which
the name of _boron_ has been given. They examined the properties of
boron in detail, but did not succeed in determining with exactness
the proportions of the constituents of boracic acid. The subsequent
experiments of Davy, though not exact, come a good deal nearer the
truth.

Their experiments on fluoric acid are exceedingly valuable. They
first obtained that acid in a state of purity, and ascertained its
properties. Their attempts to decompose it as well as those of Davy,
ended in disappointment. But Ampere conceived the idea that this
acid, like muriatic acid, is a compound of hydrogen with an unknown
supporter of combustion, to which the name _fluorine_ was given.
This opinion was adopted by Davy, and his experiments, though they
do not absolutely prove the truth of the opinion, give it at least
considerable probability, and have disposed chemists in general to
adopt it. The subsequent researches of Berzelius, while they have added
a great deal to our former knowledge respecting fluoric acid and its
compounds, have all tended to confirm and establish the doctrine that
it is a hydracid, and similar in its nature to the other hydracids. But
such is the tendency of fluorine to combine with every substance, that
hitherto it has been impossible to obtain it in an insulated state. We
want therefore, still, a decisive proof of the accuracy of the opinion.

To the experiments of Gay-Lussac and Thenard on chlorine and muriatic
acid, I have already alluded in a former part of this chapter. It was
during their investigations connected with this subject, that they
discovered _fluoboric_ acid gas, which certainly adds considerably
to the probability of the theory of Ampere respecting the nature of
fluoric acid.

I pass over a vast number of other new and important facts and
observations contained in this admirable work, which ought to be
studied with minute attention by every person who aspires at becoming a
chemist.

Besides the numerous discoveries contained in the Recherches
Physico-chimique, Gay-Lussac is the author of two of so much importance
that it would be wrong to omit them. He showed that cyanogen is one
of the constituents of prussic acid; succeeded in determining the
composition of cyanogen, and showing it to be a compound of two
atoms of carbon and one atom of azote. Prussic acid is a compound of
one atom of hydrogen and one atom of cyanogen. Sulpho-cyanic acid,
discovered by Mr. Porrett, is a compound of one atom sulphuric, and
one atom cyanogen; chloro-cyanic acid, discovered by Berthollet, is
a compound of one atom chlorine and one atom cyanogen; while cyanic
acid, discovered by Wöhler, is a compound of one atom oxygen and
one atom cyanogen. I take no notice of the fulminic acid; because,
although Gay-Lussac's experiments are exceedingly ingenious, and his
reasoning very plausible, it is not quite convincing; especially as the
results obtained by Mr. Edmund Davy, and detailed by him in his late
interesting memoir on this subject, are somewhat different.

The other discovery of Gay-Lussac is his demonstration of the peculiar
nature of iodine, his account of iodic and hydriodic acids, and of
many other compounds into which that curious substance enters as a
constituent. Sir H. Davy was occupied with iodine at the same time with
Gay-Lussac; and his sagacity and inventive powers were too great to
allow him to work upon such a substance without discovering many new
and interesting facts.

To M. Thenard we are indebted for the discovery of the important fact,
that hydrogen is capable of combining with twice as much oxygen as
exists in water, and determining the properties of this curious liquid
which has been called deutoxide of hydrogen. It possesses bleaching
properties in perfection, and I think it likely that chlorine owes its
bleaching powers to the formation of a little deutoxide of hydrogen in
consequence of its action on water.

The mantle of Davy seems in some measure to have descended on Mr.
Faraday, who occupies his old place at the Royal Institution. He has
shown equal industry, much sagacity, and great powers of invention.
The most important discovery connected with electro-magnetism, next
to the great fact, for which we are indebted to Professor Œrstedt
of Copenhagen, is due to Mr. Faraday; I mean the rotation of the
electric wires round the magnet. To him we owe the knowledge of the
fact, that several of the gases can be condensed into liquids by the
united action of pressure and cold, which has removed the barrier that
separated gaseous bodies from vapours, and shown us that all owe their
elasticity to the same cause. To him also we owe the knowledge of the
important fact, that chlorine is capable of combining with carbon. This
has considerably improved the history of chlorine and served still
further to throw new light on the analogy which exists between all the
supporters of combustion. They are doubtless all of them capable of
combining with every one of the other simple bodies, and of forming
compounds with them. For they are all negative bodies; while the other
simple substances without exception, when compared to them, possess
positive properties. We must therefore view the history of chemistry as
incomplete, till we have become acquainted with the compounds of every
supporter with every simple base.




CHAPTER VI.

OF THE ATOMIC THEORY.


I come now to the last improvement which chemistry has received--an
improvement which has given a degree of accuracy to chemical
experimenting almost approaching to mathematical precision, which has
simplified prodigiously our views respecting chemical combinations;
which has enabled manufacturers to introduce theoretical improvements
into their processes, and to regulate with almost perfect precision the
relative quantities of the various constituents necessary to produce
the intended effects. The consequence of this is, that nothing is
wasted, nothing is thrown away. Chemical products have become not only
better in quality, but more abundant and much cheaper. I allude to the
atomic theory still only in its infancy, but already productive of
the most important benefits. It is destined one day to produce still
more wonderful effects, and to render chemistry not only the most
delightful, but the most useful and indispensable, of all the sciences.

Like all other great improvements in science, the atomic theory
developed itself by degrees, and several of the older chemists
ascertained facts which might, had they been aware of their importance,
have led them to conclusions similar to those of the moderns. The
very attempt to analyze the salts was an acknowledgment that bodies
united with each other in definite proportions: and these definite
proportions, had they been followed out, would have led ultimately to
the doctrine of atoms. For how could it be, that six parts of potash
were always saturated by five parts of sulphuric acid and 6·75 parts
of nitric acid? How came it that five of sulphuric acid always went as
far in saturating potash as 6·75 of nitric acid? It was known, that
in chemical combinations it was the ultimate particles of matter that
combined. The simple explanation, therefore, would have been--that the
weight of an ultimate particle of sulphuric acid was only five, while
that of an ultimate particle of nitric acid was 6·75. Had such an
inference been drawn, it would have led directly to the atomic theory.

The atomic theory in chemistry has many points of resemblance to
the fluxionary calculus in mathematics. Both give us the ratios
of quantities; both reduce investigations that would be otherwise
extremely difficult, or almost impossible, to the utmost simplicity;
and what is still more curious, both have been subjected to the same
kind of ridicule by those who have not put themselves to the trouble of
studying them with such attention as to understand them completely. The
minute philosopher of Berkeley, _mutatis mutandis_, might be applied to
the atomic theory with as much justice as to the fluxionary calculus;
and I have heard more than one individual attempt to throw ridicule
upon the atomic theory by nearly the same kind of arguments.

The first chemists, then, who attempted to analyze the salts may be
considered as contributing towards laying the foundation of the atomic
theory, though they were not themselves aware of the importance of the
structure which might have been raised upon their experiments, had
they been made with the requisite precision.

Bergman was the first chemist who attempted regular analyses of salts.
It was he that first tried to establish regular formulas for the
analyses of mineral waters, stones, and ores, by the means of solution
and precipitation. Hence a knowledge of the constituents of the salts
was necessary, before his formulas could be applied to practice. It was
to supply this requisite information that he set about analyzing the
salts, and his results were long considered by chemists as exact, and
employed by them to determine the results of their analyses. We now
know that these analytical results of Bergman are far from accurate;
they have accordingly been laid aside as useless: but this knowledge
has been derived from the progress of the atomic theory.

The first accurate set of experiments to analyze the salts was made by
Wenzel, and published by him in 1777, in a small volume entitled "Lehre
von der Verwandschaft der Körper," or, "Theory of the Affinities of
Bodies." These analyses of Wenzel are infinitely more accurate than
those of Bergman, and indeed in many cases are equally precise with
the best which we have even at the present day. Yet the book fell
almost dead-born from the press; Wenzel's results never obtained the
confidence of chemists, nor is his name ever quoted as an authority.
Wenzel was struck with a phenomenon, which had indeed been noticed
by preceding chemists; but they had not drawn the advantages from it
which it was capable of affording. There are several saline solutions
which, when mixed with each other, completely decompose each other, so
that two new salts are produced. Thus, if we mix together solutions
of nitrate of lead and sulphate of soda in the requisite proportions,
the sulphuric acid of the latter salt will combine with the oxide of
lead of the former, and will form with it sulphate of lead, which will
precipitate to the bottom in the state of an insoluble powder, while
the nitric acid formerly united to the oxide of lead, will combine with
the soda formerly in union with the sulphuric acid, and form nitrate of
soda, which being soluble, will remain in solution in the liquid. Thus,
instead of the two old salts,

  Sulphate of soda
  Nitrate of lead,

we obtain the two new salts,

  Sulphate of lead
  Nitrate of soda.

If we mix the two salts in the requisite proportions, the decomposition
will be complete; but if there be an excess of one of the salts, that
excess will still remain in solution without affecting the result. If
we suppose the two salts anhydrous, then the proportions necessary for
complete decomposition are,

  Sulphate of soda    9
  Nitrate of lead    20·75
                    ------
                     29·75

and the quantities of the new salts formed will be

  Sulphate of lead    19
  Nitrate of soda     10·75
                      -----
                      29·75

We see that the absolute weights of the two sets of salts are the
same: all that has happened is, that both the acids and both the bases
have exchanged situations. Now if, instead of mixing these two salts
together in the preceding proportions, we employ

  Sulphate of soda    9
  Nitrate of lead    25·75

That is to say, if we employ 5 parts of nitrate of lead more than
is sufficient for the purpose; we shall have exactly the same
decompositions as before; but the 5 of excess of nitrate of lead will
remain in solution, mixed with the nitrate of soda. There will be
precipitated as before,

  Sulphate of lead 19

and there will remain in solution a mixture of

  Nitrate of soda  10·75
  Nitrate of lead   5

The phenomena are precisely the same as before; the additional 5 of
nitrate of lead have occasioned no alteration; the decomposition has
gone on just as if they had not been present.

Now the phenomena which drew the particular attention of Wenzel is,
that if the salts were neutral before being mixed, the neutrality
was not affected by the decomposition which took place on their
mixture.[7] A salt is said to be neutral when it neither possesses the
characters of an acid or an alkali. Acids _redden_ vegetable _blues_,
while alkalies render them _green_. A neutral salt produces no effect
whatever upon vegetable blues. This observation of Wenzel is very
important: it is obvious that the salts, after their decomposition,
could not have remained neutral unless the elements of the two salts
had been such that the bases in each just saturated the acids in either
of the salts.

 [7] This observation is not without exception. It does not hold when
 one of the salts is a phosphate or an arseniate, and this is the cause
 of the difficulty attending the analysis of these genera of salts.

The constituents of the two salts are as follows:

                         { 5    sulphuric acid
   9    sulphate of soda { 4    soda,

                         { 6·75 nitric acid
  20·75 nitrate of lead  {14    oxide of lead.

Now it is clear, that unless 5 sulphuric acid were just saturated by
4 soda and by 14 oxide of lead; and 6·75 of nitric acid by the same 4
soda and 14 oxide of lead, the salts, after their decomposition, could
not have preserved their neutrality. Had 4 soda required only 5·75 of
nitric acid, or had 14 oxide of lead required only 4 sulphuric acid, to
saturate them, the liquid, after decomposition, would have contained
an excess of acid. As no such excess exists, it is clear that in
saturating an acid, 4 soda goes exactly as far as 14 oxide of lead; and
that, in saturating a base, 5 sulphuric acid goes just as far as 6·75
nitric acid.

Nothing can exhibit in a more striking point of view, the almost
despotic power of fashion and authority over the minds even of men
of science, and the small number of them that venture to think for
themselves, than the fact, that this most important and luminous
explanation of Wenzel, confirmed by much more accurate experiments than
any which chemistry had yet seen, is scarcely noticed by any of his
contemporaries, and seems not to have attracted the smallest attention.
In science, it is as unfortunate for a man to get before the age in
which he lives, as to continue behind it. The admirable explanation of
combustion by Hooke, and the important experiments on combustion and
respiration by Mayow, were lost upon their contemporaries, and procured
them little or no reputation whatever; while the same theory, and
the same experiments, advanced by Lavoisier and Priestley, a century
later, when the minds of men of science were prepared to receive them,
raised them to the very first rank among philosophers, and produced a
revolution in chemistry. So much concern has fortune, not merely in the
success of kings and conquerors, but in the reputation acquired by men
of science.

In the year 1792 another labourer, in the same department of chemistry,
appeared: this was Jeremiah Benjamin Richter, a Prussian chemist, of
whose history I know nothing more than that his publications were
printed and published in Breslau, from which I infer that he was a
native of, or at least resided in, Silesia. He calls himself Assessor
of the Royal Prussian Mines and Smeltinghouses, and Arcanist of the
Commission of Berlin Porcelain Manufacture. He died in the prime of
life, on the 4th of May, 1807. In the year 1792 he published a work
entitled "Anfansgründe der Stochyometrie; oder, Messkunst Chymischer
Elemente" (Elements of Stochiometry; or, the Mathematics of the
Chemical Elements). A second and third volume of this work appeared in
1793, and a fourth volume in 1794. The object of this book was a rigid
analysis of the different salts, founded on the fact just mentioned,
that when two salts decompose each other, the salts newly formed
are neutral as well as those which have been decomposed. He took up
the subject nearly in the same way as Wenzel had done, but carried
the subject much further; and endeavoured to determine the capacity
of saturation of each acid and base, and to attach numbers to each,
indicating the weights which mutually saturate each other. He gave the
whole subject a mathematical dress, and endeavoured to show that the
same relation existed, between the numbers representing the capacity of
saturation of these bodies, as does between certain classes of figurate
numbers. When we strip the subject of the mystical form under which he
presented it, the labours of Richter may be exhibited under the two
following tables, which represent the capacity of saturation of the
acids and bases, according to his experiments.

  1. ACIDS.

  Fluoric acid    427
  Carbonic        577
  Sebacic         706
  Muriatic        712
  Oxalic          755
  Phosphoric      979
  Formic          988
  Sulphuric      1000
  Succinic       1209
  Nitric         1405
  Acetic         1480
  Citric         1683
  Tartaric       1694


  2. BASES.

  Alumina         525
  Magnesia        615
  Ammonia         672
  Lime            793
  Soda            859
  Strontian      1329
  Potash         1605
  Barytes        2222

To understand this table, it is only necessary to observe, that if we
take the quantity of any of the acids placed after it in the table,
that quantity will be exactly saturated by the weight of each base put
after it in the second column: thus, 1000 of sulphuric acid will be
just saturated by 525 alumina, 615 magnesia, 672 ammonia, 793 lime, and
so on. On the other hand, the quantity of any base placed after its
name in the second column, will be just saturated by the weight of each
acid placed after its name in the first column: thus, 793 parts of lime
will be just saturated by 427 of fluoric acid, 577 of carbonic acid,
706 of sebacic acid, and so on.

This work of Richter was followed by a periodical work entitled "Ueber
die neuern Gegenstande der Chymie" (On the New Objects of Chemistry).
This work was begun in the year 1792, and continued in twelve different
numbers, or volumes, to the time of his death in 1807.[8]

 [8] I have only seen eleven parts of this work, the last of which
 appeared in 1802; but I believe that a twelfth part was published
 afterwards.

Richter's labours in this important field produced as little attention
as those of Wenzel. Gehlen wrote a short panegyric upon him at his
death, praising his views and pointing out their importance; but I
am not aware of any individual, either in Germany or elsewhere, who
adopted Richter's opinions during his lifetime, or even seemed aware
of their importance, unless we are to except Berthollet, who mentions
them with approbation in his Chemical Statics. This inattention was
partly owing to the great want of accuracy which it is impossible
not be sensible of in Richter's experiments. He operated upon too
large quantities of matter, which indeed was the common defect of the
times, and was first checked by Dr. Wollaston. The dispute between the
phlogistians and the antiphlogistians, which was not fully settled in
Richter's time, drew the attention of chemists to another branch of
the subject. Richter in some measure went before the age in which he
lived, and had his labours not been recalled to our recollection by the
introduction of atomic theory, he would probably have been forgotten,
like Hooke and Mayow, and only brought again under review after the
new discoveries in the science had put it in the power of chemists in
general to appreciate the value of his labours.

It is to Mr. Dalton that we are indebted for the happy and simple idea
from which the atomic theory originated.

John Dalton, to whose lot it has fallen to produce such an alteration
and improvement in chemistry, was born in Westmorland, and belongs
to that small and virtuous sect known in this country by the name of
Quakers. When very young he lived with Mr. Gough of Kendal, a blind
philosopher, to whom he read, and whom he assisted in his philosophical
investigations. It was here, probably, that he acquired a considerable
part of his education, particularly his taste for mathematics. For
Mr. Gough was remarkably fond of mathematical investigations, and has
published several mathematical papers that do him credit. From Kendal
Mr. Dalton went to Manchester, about the beginning of the present
century, and commenced teaching elementary mathematics to such young
men as felt inclined to acquire some knowledge of that important
subject. In this way, together with a few courses of lectures on
chemistry, which he has occasionally given at the Royal Institution
in London, at the Institution in Birmingham, in Manchester, and once
in Edinburgh and in Glasgow, he has contrived to support himself for
more than thirty years, if not in affluence, at least in perfect
independence. And as his desires have always been of the most moderate
kind, his income has always been equal to his wants. In a country
like this, where so much wealth abounds, and where so handsome a
yearly income was subscribed to enable Dr. Priestley to prosecute
his investigations undisturbed and undistracted by the necessity of
providing for the daily wants of his family, there is little doubt
that Mr. Dalton, had he so chosen it, might, in point of pecuniary
circumstances, have exhibited a much more brilliant figure. But he has
displayed a much nobler mind by the career which he has chosen--equally
regardless of riches as the most celebrated sages of antiquity, and as
much respected and beloved by his friends, even in the rich commercial
town of Manchester, as if he were one of the greatest and most
influential men in the country. Towards the end of the last century, a
literary and scientific society had been established in Manchester, of
which Mr. Thomas Henry, the translator of Lavoisier's Essays, and who
distinguished himself so much in promoting the introduction of the new
mode of bleaching into Lancashire, was long president. Mr. Dalton, who
had already distinguished himself by his meteorological observations,
and particularly by his account of the Aurora Borealis, soon became a
member of the society; and in the fifth volume of their Memoirs, part
II., published in 1802, six papers of his were inserted, which laid the
foundation of his future celebrity. These papers were chiefly connected
with meteorological subjects; but by far the most important of them all
was the one entitled "Experimental Essays on the Constitution of mixed
Gases; on the Force of Steam or Vapour from water and other liquids in
different temperatures, both in a torricellian vacuum and in air; on
Evaporation; and on the Expansion of Gases by Heat."

From a careful examination of all the circumstances, he considered
himself as entitled to infer, that when two elastic fluids or gases,
A and B, are mixed together, there is no mutual repulsion among their
particles; that is, the particles of A do not repel those of B, as they
do one another. Consequently, the pressure or whole weight upon any
one particle arises solely from those of its own kind. This doctrine
is of so startling a nature and so contrary to the opinions previously
received, that chemists have not been much disposed to admit it. But at
the same time it must be confessed, that no one has hitherto been able
completely to refute it. The consequences of admitting it are obvious:
we should be able to account for a fact which has been long known,
though no very satisfactory reason for it had been assigned; namely,
that if two gases be placed in two separate vessels, communicating
by a narrow orifice, and left at perfect rest in a place where the
temperature never varies, if we examine them after a certain interval
of time we shall find both equally diffused through both vessels. If we
fill a glass phial with hydrogen gas and another phial with common air
or carbonic acid gas and unite the two phials by a narrow glass tube
two feet long, filled with common air, and place the phial containing
the hydrogen gas uppermost, and the other perpendicularly below it, the
hydrogen, though lightest, will not remain in the upper phial, nor the
carbonic acid, though heaviest, in the undermost phial; but we shall
find both gases equally diffused through both phials.

But the second of these essays is by far the most important. In it he
establishes, by the most unexceptionable evidence, that water, when
it evaporates, is always converted into an elastic fluid, similar in
its properties to air. But that the distance between the particles is
greater the lower the temperature is at which the water evaporates.
The elasticity of this vapour increases as the temperature increases.
At 32° it is capable of balancing a column of mercury about half an
inch in height, and at 212° it balances a column thirty inches high,
or it is then equal to the pressure of the atmosphere. He determined
the elasticity of vapour at all temperatures from 32° to 212°, pointed
out the method of determining the quantity of vapour that at any time
exists in the atmosphere, the effect which it has upon the volume of
air, and the mode of determining its quantity. Finally, he determined,
experimentally, the rate of evaporation from the surface of water at
all temperatures from 32° to 212°. These investigations have been of
infinite use to chemists in all their investigations respecting the
specific gravity of gases, and have enabled them to resolve various
interesting problems, both respecting specific gravity, evaporation,
rain and respiration, which, had it not been for the principles laid
down in this essay, would have eluded their grasp.

In the last essay contained in this paper he has shown that all elastic
fluids expand the same quantity by the same addition of heat, and this
expansion is very nearly 1-480th part for every degree of Fahrenheit's
thermometer. In this last branch of the subject Mr. Dalton was followed
by Gay-Lussac, who, about half a year after the appearance of his
Essays, published a paper in the Annales de Chimie, showing that the
expansion of all elastic fluids, when equally heated, is the same. Mr.
Dalton concluded that the expansion of all elastic fluids by heat is
equable. And this opinion has been since confirmed by the important
experiments of Dulong and Petit, which have thrown much additional
light on the subject.

In the year 1804, on the 26th of August, I spent a day or two at
Manchester, and was much with Mr. Dalton. At that time he explained to
me his notions respecting the composition of bodies. I wrote down at
the time the opinions which he offered, and the following account is
taken literally from my journal of that date:

The ultimate particles of all simple bodies are _atoms_ incapable
of further division. These atoms (at least viewed along with their
atmospheres of heat) are all spheres, and are each of them possessed of
particular weights, which may be denoted by numbers. For the greater
clearness he represented the atoms of the simple bodies by symbols. The
following are his symbols for four simple bodies, together with the
numbers attached to them by him in 1804:

                         Relative
                         weights.
  [oxygen]   Oxygen        6·5
  [hydrogen] Hydrogen      1
  [carbon]   Carbon        5
  [azote]    Azote         5

The following symbols represent the way in which he thought these atoms
were combined to form certain binary compounds, with the weight of an
integrant particle of each compound:

                                     Weights.
  [oxygen][hydrogen] Water             7·5
  [oxygen][azote]    Nitrous gas      11·5
  [carbon][hydrogen] Olefiant gas      6
  [azote][hydrogen]  Ammonia           6
  [oxygen][carbon]   Carbonic oxide   11·5

The following were the symbols by which he represented the composition
of certain tertiary compounds:

                                                    Weights.
  [oxygen][carbon][oxygen]     Carbonic acid          18
  [oxygen][azote][oxygen]      Nitrous oxide          16·5
  [carbon][hydrogen][carbon]   Ether                  11
  [hydrogen][carbon][hydrogen] Carburetted hydrogen    7
  [oxygen][azote][oxygen]      Nitric acid            18

A quaternary compound:

  [oxygen][azote][oxygen] Oxynitric acid            24·5
          [oxygen]

A quinquenary compound:

        [oxygen]
  [azote]      [azote][oxygen] Nitrous acid         29·5
        [oxygen]

A sextenary compound:

  [carbon][oxygen][carbon]      Alcohol             23·5
  [hydrogen][carbon][hydrogen]

These symbols are sufficient to give the reader an idea of the notions
entertained by Dalton respecting the nature of compounds. Water is
a compound of one atom oxygen and one atom hydrogen as is obvious
from the symbol [oxygen][hydrogen]. Its weight 7·5 is that of an atom
of oxygen and an atom of hydrogen united together. In the same way
carbonic oxide is a compound of one atom oxygen and one atom carbon.
Its symbol is [oxygen][carbon], and its weight 11·5 is equal to an
atom of oxygen and an atom of carbon added together. Carbonic acid is
a tertiary compound, or it consists of three atoms united together;
namely, two atoms of oxygen and one atom of carbon. Its symbol is
[oxygen][carbon][oxygen], and its weight 18. A bare inspection of the
symbols and weights will make Mr. Dalton's notions respecting the
constitution of every body in the table evident to every reader.

It was this happy idea of representing the atoms and constitution of
bodies by symbols that gave Mr. Dalton's opinions so much clearness.
I was delighted with the new light which immediately struck my
mind, and saw at a glance the immense importance of such a theory,
when fully developed. Mr. Dalton informed me that the atomic theory
first occurred to him during his investigations of olefiant gas and
carburetted hydrogen gases, at that time imperfectly understood, and
the constitution of which was first fully developed by Mr. Dalton
himself. It was obvious from the experiments which he made upon them,
that the constituents of both were carbon and hydrogen, and nothing
else. He found further, that if we reckon the carbon in each the same,
then carburetted hydrogen gas contains exactly twice as much hydrogen
as olefiant gas does. This determined him to state the ratios of these
constituents in numbers, and to consider the olefiant gas as a compound
of one atom of carbon and one atom of hydrogen; and carburetted
hydrogen of one atom of carbon and two atoms of hydrogen. The idea
thus conceived was applied to carbonic oxide, water ammonia, &c.; and
numbers representing the atomic weights of oxygen, azote, &c., deduced
from the best analytical experiments which chemistry then possessed.

Let not the reader suppose that this was an easy task. Chemistry at
that time did not possess a single analysis which could be considered
as even approaching to accuracy. A vast number of facts had been
ascertained, and a fine foundation laid for future investigation; but
nothing, as far as weight and measure were concerned, deserving the
least confidence, existed. We need not be surprised, then, that Mr.
Dalton's first numbers were not exact. It required infinite sagacity,
and not a little labour, to come so near the truth as he did. How could
accurate analyses of gases be made when there was not a single gas
whose specific gravity was known, with even an approach to accuracy;
the preceding investigations of Dalton himself paved the way for
accuracy in this indispensable department; but still accurate results
had not yet been obtained.

In the third edition of my System of Chemistry, published in 1807, I
introduced a short sketch of Mr. Dalton's theory, and thus made it
known to the chemical world. The same year a paper of mine on _oxalic
acid_ was published in the Philosophical Transactions, in which I
showed that oxalic acid unites in two proportions with strontian,
forming an _oxalate_ and _binoxalate_; and that, supposing the
strontian in both salts to be the same, the oxalic acid in the latter
is exactly twice as much as in the former. About the same time, Dr.
Wollaston showed that bicarbonate of potash contains just twice the
quantity of carbonic acid that exists in carbonate of potash; and that
there are three oxalates of potash; viz., _oxalate_, _binoxalate_, and
_quadroxalate_; the weight of acids in each of which are as the numbers
1, 2, 4. These facts gradually drew the attention of chemists to Mr.
Dalton's views. There were, however, some of our most eminent chemists
who were very hostile to the atomic theory. The most conspicuous
of these was Sir Humphry Davy. In the autumn of 1807 I had a long
conversation with him at the Royal Institution, but could not convince
him that there was any truth in the hypothesis. A few days after I
dined with him at the Royal Society Club, at the Crown and Anchor,
in the Strand. Dr. Wollaston was present at the dinner. After dinner
every member of the club left the tavern, except Dr. Wollaston, Mr.
Davy, and myself, who staid behind and had tea. We sat about an hour
and a half together, and our whole conversation was about the atomic
theory. Dr. Wollaston was a convert as well as myself; and we tried to
convince Davy of the inaccuracy of his opinions; but, so far from being
convinced, he went away, if possible, more prejudiced against it than
ever. Soon after, Davy met Mr. Davis Gilbert, the late distinguished
president of the Royal Society; and he amused him with a caricature
description of the atomic theory, which he exhibited in so ridiculous a
light, that Mr. Gilbert was astonished how any man of sense or science
could be taken in with such a tissue of absurdities. Mr. Gilbert
called on Dr. Wollaston (probably to discover what could have induced
a man of Dr. Wollaston's sagacity and caution to adopt such opinions),
and was not sparing in laying the absurdities of the theory, such as
they had been represented to him by Davy, in the broadest point of
view. Dr. Wollaston begged Mr. Gilbert to sit down, and listen to
a few facts which he would state to him. He then went over all the
principal facts at that time known respecting the salts; mentioned the
alkaline carbonates and bicarbonates, the oxalate, binoxalate, and
quadroxalate of potash, carbonic oxide and carbonic acid, olefiant gas,
and carburetted hydrogen; and doubtless many other similar compounds,
in which the proportion of one of the constituents increases in a
regular ratio. Mr. Gilbert went away a convert to the truth of the
atomic theory; and he had the merit of convincing Davy that his former
opinions on the subject were wrong. What arguments he employed I do
not know; but they must have been convincing ones, for Davy ever after
became a strenuous supporter of the atomic theory. The only alteration
which he made was to substitute _proportion_ for Dalton's word, _atom_.
Dr. Wollaston substituted for it the term _equivalent_. The object of
these substitutions was to avoid all theoretical annunciations. But, in
fact, these terms, _proportion_, _equivalent_, are neither of them so
convenient as the term _atom_: and, unless we adopt the hypothesis with
which Dalton set out, namely, that the ultimate particles of bodies are
_atoms_ incapable of further division, and that chemical combination
consists in the union of these atoms with each other, we lose all the
new light which the atomic theory throws upon chemistry, and bring our
notions back to the obscurity of the days of Bergman and of Berthollet.

In the year 1808 Mr. Dalton published the first volume of his New
System of Chemical Philosophy. This volume consists chiefly of two
chapters: the first, on _heat_, occupies 140 pages. In it he treats of
all the effects of heat, and shows the same sagacity and originality
which characterize all his writings. Even when his opinions on a
subject are not correct, his reasoning is so ingenious and original,
and the new facts which he contrives to bring forward so important,
that we are always pleased and always instructed. The second chapter,
on the _constitution of bodies_, occupies 70 pages. The chief object
of it is to combat the peculiar notions respecting elastic fluids,
which had been advanced by Berthollet, and supported by Dr. Murray,
of Edinburgh. In the third chapter, on _chemical synthesis_, which
occupies only a few pages, he gives us the outlines of the atomic
theory, such as he had conceived it. In a plate at the end of the
volume he exhibits the symbols and atomic weights of thirty-seven
bodies, twenty of which were then considered as simple, and the other
seventeen as compound. The following table shows the atomic weight of
the simple bodies, as he at that time had determined them from the best
analytical experiments that had been made:

           Weight of
             atom.
  Hydrogen     1
  Azote        5
  Carbon       5
  Oxygen       7
  Phosphorus   9
  Sulphur     13
  Magnesia    20
  Lime        23
  Soda        28
  Potash      42
  Strontian   46
  Barytes     68
  Iron        38
  Zinc        56
  Copper      56
  Lead        95
  Silver     100
  Platinum   100
  Gold       140
  Mercury    167

He had made choice of hydrogen for unity, because it is the lightest
of all bodies. He was of opinion that the atomic weights of all other
bodies are multiples of hydrogen; and, accordingly, they are all
expressed in whole numbers. He had raised the atomic weight of oxygen
from 6·5 to 7, from a more careful examination of the experiments
on the component parts of water. Davy, from a more accurate set of
experiments, soon after raised the number for oxygen to 7·5: and
Dr. Prout, from a still more careful investigation of the relative
specific gravities of oxygen and hydrogen, showed that if the atom of
hydrogen be 1, that of oxygen must be 8. Every thing conspires to prove
that this is the true ratio between the atomic weights of oxygen and
hydrogen.

In 1810 appeared the second volume of Mr. Dalton's New System of
Chemical Philosophy. In it he examines the elementary principles,
or simple bodies, namely, oxygen, hydrogen, azote, carbon, sulphur,
phosphorus, and the metals; and the compounds consisting of two
elements, namely, the compounds of oxygen with hydrogen, azote,
carbon, sulphur, phosphorus; of hydrogen with azote, carbon, sulphur,
phosphorus. Finally he treats of the fixed alkalies and earths. All
these combinations are treated of with infinite sagacity; and he
endeavours to determine the atomic weights of the different elementary
substances. Nothing can exceed the ingenuity of his reasoning. But
unfortunately at that time very few accurate chemical analyses existed;
and in chemistry no reasoning, however ingenious, can compensate for
this indispensable datum. Accordingly his table of atomic weights at
the end this second volume, though much more complete than that at the
end of the first volume, is still exceedingly defective; indeed no one
number can be considered as perfectly correct.

The third volume of the New System of Chemical Philosophy was only
published in 1827; but the greatest part of it had been printed nearly
ten years before. It treats of the metallic oxides, the sulphurets,
phosphurets, carburets, and alloys. Doubtless many of the facts
contained in it were new when the sheets were put to the press; but
during the interval between the printing and publication, almost the
whole of them had not merely been anticipated, but the subject carried
much further. By far the most important part of the volume is the
Appendix, consisting of about ninety pages, in which he discusses,
with his usual sagacity, various important points connected with heat
and vapour. In page 352 he gives a new table of the atomic weights of
bodies, much more copious than those contained in the two preceding
volumes; and into which he has introduced the corrections necessary
from the numerous correct analyses which had been made in the interval.
He still adheres to the ratio 1:7 as the correct difference between the
weights of the atoms of hydrogen and oxygen. This shows very clearly
that he has not attended to the new facts which have been brought
forward on the subject. No person who has attended to the experiments
made on the specific gravity of these two gases during the last twelve
years, could admit that these specific gravities are to each other as 1
to 14. If 1 to 16 be not the exact ratio, it will surely be admitted on
all hands that it is infinitely near it.

Mr. Dalton represented the weight of an atom of hydrogen by 1, because
it is the lightest of bodies. In this he has been followed by the
chemists of the Royal Institution, by Mr. Philips, Dr. Henry, and
Dr. Turner, and perhaps some others whose names I do not at present
recollect. Dr. Wollaston, in his paper on Chemical Equivalents,
represented the atomic weight of oxygen by 1, because it enters into
a greater number of combinations than any other substance; and this
plan has been adopted by Berzelius, by myself, and by the greater
number, if not the whole, of the chemists on the continent. Perhaps the
advantage which Dr. Wollaston assigned for making the atom of oxygen
unity will ultimately disappear: for there is no reason for believing
that the other supporters of combustion are not capable of entering
into as many compounds as oxygen. But, from the constitution of the
atmosphere, it is obvious that the compounds into which oxygen enters
will always be of more importance to us than any others; and in this
point of view it may be attended with considerable convenience to have
oxygen represented by 1. In the present state of the atomic theory
there is another reason for making the atom of oxygen unity, which I
think of considerable importance. Chemists are not yet agreed about the
atom of hydrogen. Some consider water a compound of 1 atom of oxygen
and 2 atoms of hydrogen; others, of 1 atom of oxygen and 1 atom of
hydrogen. According to the first view, the atom of hydrogen is only
1-16th of the weight of an atom of oxygen; according to the second, it
is 1-8th. If, therefore, we were to represent the atom of hydrogen by
1, the consequence would be, that two tables of atomic weights would be
requisite--all the atoms in one being double the weight of the atoms in
the other: whereas, if we make the atom of oxygen unity, it will be the
atom of hydrogen only that will differ in the two tables. In the one
table it will be 0·125, in the other it will be 0·0625: or, reckoning
with Berzelius the atom of oxygen = 100, we have that of hydrogen =
12·5 or 6·25, according as we view water to be a compound of 1 atom of
oxygen with 1 or 2 atoms of hydrogen.

In the year 1809 Gay-Lussac published in the second volume of the
Mémoires d'Arcueil a paper on the union of the gaseous substances with
each other. In this paper he shows that the proportions in which the
gases unite with each other are of the simplest kind. One volume of one
gas either combining with one volume of another, or with two volumes,
or with half a volume. The atomic theory of Dalton had been opposed
with considerable keenness by Berthollet in his Introduction to the
French translation of my System of Chemistry. Nor was this opposition
to be wondered at; because its admission would of course overturn all
the opinions which Berthollet had laboured to establish in his Chemical
Statics. The object of Gay-Lussac's paper was to confirm and establish
the new atomic theory, by exhibiting it in a new point of view. Nothing
can be more ingenious than his mode of treating the subject, or more
complete than the proofs which he brings forward in support of it. It
had been already established that water is formed by the union of one
volume of oxygen and two volumes of hydrogen gas. Gay-Lussac found by
experiment, that one volume of muriatic acid gas is just saturated by
one volume of ammoniacal gas: the product is sal ammoniac. Fluoboric
acid gas unites in two proportions with ammoniacal gas: the first
compound consists of one volume of fluoboric gas, and one volume of
ammoniacal; the second, of one volume of the acid gas, and two volumes
of the alkaline. The first forms a neutral salt, the second an alkaline
salt. He showed likewise, that carbonic acid and ammoniacal gas could
combine also in two proportions; namely, one volume of the acid gas
with one or two volumes of the alkaline gas.

M. Amédée Berthollet had proved that ammonia is a compound of one
volume of azotic, and three volumes of hydrogen gas. Gay-Lussac himself
had shown that sulphuric acid is composed of one volume sulphurous
acid gas, and a half-volume of oxygen gas. He showed further, that the
compounds of azote and oxygen were composed as follows:

                   Azote.       Oxygen.
  Protoxide of azote 1 volume + ½ volume
  Deutoxide of azote 1    "   + 1
  Nitrous acid       1    "   + 2

He showed also, that when the two gases after combining remained in the
gaseous state, the diminution of volume was either 0, or ⅓, or ½.

The constancy of these proportions left no doubt that the combinations
of all gaseous bodies were definite. The theory of Dalton applied to
them with great facility. We have only to consider a volume of gas
to represent an atom, and then we see that in gases one atom of one
gas combines either with one, two, or three atoms of another gas, and
never with more. There is, indeed, a difficulty occasioned by the way
in which we view the composition of water. If water be composed of
one atom of oxygen and one atom of hydrogen, then it follows that a
volume of oxygen contains twice as many atoms as a volume of hydrogen.
Consequently, if a volume of hydrogen gas represent an atom, half a
volume of oxygen gas must represent an atom.

Dr. Prout soon after showed that there is an intimate connexion between
the atomic weight of a gas and its specific gravity. This indeed is
obvious at once. I afterwards showed that the specific gravity of a
gas is either equal to its atomic weight multiplied by 1·111[.1] (the
specific gravity of oxygen gas), or by 0·555[.5] (half the specific
gravity of oxygen gas), or by O·277[.7] (1-4th of the specific
gravity of oxygen gas), these differences depending upon the relative
condensation which the gases undergo when their elements unite. The
following table exhibits the atoms and specific gravity of these three
sets of gases:

  I. Sp. Gr. = Atomic Weight × 1·1111

                  Atomic        Sp.
                  weight.     gravity.
  Oxygen gas        1         1·1111
  Fluosilicic acid  3·25      3·6111

II. Sp. Gr. = Atomic Weight × 0·555[.5].

                      Atomic weight.  Sp. gravity.
  Hydrogen               0·125         0·069[.4]
  Azotic                 1·75          0·072[.2]
  Chlorine               4·5           2·5
  Carbon vapour          0·75          0·416[.6]
  Phosphorus vapour      2             1·111[.1]
  Sulphur vapour         2             1·111[.1]
  Tellurium vapour       4             2·222[.2]
  Arsenic vapour         4·75          2·638[.8]
  Selenium vapour        5             2·777[.7]
  Bromine vapour        10             5·555[.5]
  Iodine vapour         15·75          8·75
  Steam                  1·125         0·625
  Carbonic oxide gas     1·75          0·972[.2]
  Carbonic acid          2·75          1·527[.7]
  Protoxide of azote     2·75          1·527[.7]
  Nitric acid vapour     6·75          3·75
  Sulphurous acid        4             2.222[.2]
  Sulphuric acid vapour  5             2·777[.7]
  Cyanogen               3·25          1·805[.5]
  Fluoboric acid         4·25          2·361[.1]
  Bisulphuret of carbon  4·75          2·638[.8]
  Chloro-carbonic acid   6·25          3·472[.2]


III. Sp. Gr. = Atomic Weight × 0·277[.7].

                     Atomic weight.  Sp. gravity.
  Ammoniacal gas         2·125         0·5902[.7]
  Hydrocyanic acid       3·375         0·9375
  Deutoxide of azote     3·75          1·041[.6]
  Muriatic acid          4·625         1·2847[.2]
  Hydrobromic acid      10·125         2·8125
  Hydriodic acid        15·875         4·40973

 [Transcriber's Note: The numbers within [] thus [.2] represent numbers
 with a dot above them in the original.]

When Professor Berzelius, of Stockholm, thought of writing his
Elementary Treatise on Chemistry, the first volume of which was
published in the year 1808, he prepared himself for the task by reading
several chemical works which do not commonly fall under the eye of
those who compose elementary treatises. Among other books he read the
Stochiometry of Richter, and was much struck with the explanations
there given of the composition of salts, and the precipitation of
metals by each other. It followed from the researches of Richter, that
if we were in possession of good analyses of certain salts, we might
by means of them calculate with accuracy the composition of all the
rest. Berzelius formed immediately the project of analyzing a series
of salts with the most minute attention to accuracy. While employed in
putting this project in execution, Davy discovered the constituents
of the alkalies and earths, Mr. Dalton gave to the world his notions
respecting the atomic theory, and Gay-Lussac made known his theory of
volumes. This greatly enlarged his views as he proceeded, and induced
him to embrace a much wider field than he had originally contemplated.
His first analyses were unsatisfactory; but by repeating them and
varying the methods, he detected errors, improved his processes, and
finally obtained results, which agreed exceedingly well with the
theoretical calculations. These laborious investigations occupied him
several years. The first outline of his experiments appeared in the
77th volume of the Annales de Chimie, in 1811, in a letter addressed
by Berzelius to Berthollet. In this letter he gives an account of
his methods of analyses together with the composition of forty-seven
compound bodies. He shows that when a metallic protosulphuret is
converted into a sulphate, the sulphate is neutral; that an atom of
sulphur is twice as heavy as an atom of oxygen; and that when sulphite
of barytes is converted into sulphate, the sulphate is neutral, there
being no excess either of acid or base. From these and many other
important facts he finally draws this conclusion: "In a compound formed
by the union of two oxides, the one which (when decomposed by the
galvanic battery) attaches itself to the positive pole (the _acid_ for
example) contains two, three, four, five, &c., times as much oxygen,
as the one which attaches itself to the negative pole (the alkali,
earth, or metallic oxide)." Berzelius's essay itself appeared in the
third volume of the Afhandlingar, in 1810. It was almost immediately
translated into German, and published by Gilbert in his Annalen der
Physik. But no English translation has ever appeared, the editors of
our periodical works being in general unacquainted with the German
and other northern languages. In 1815 Berzelius applied the atomic
theory to the mineral kingdom, and showed with infinite ingenuity that
minerals are chemical compounds in definite or atomic proportions, and
by far the greater number of them combinations of acids and bases. He
applied the theory also to the vegetable kingdom by analyzing several
of the vegetable acids, and showing their atomic constitution. But
here a difficulty occurs, which in the present state of our knowledge,
we are unable to surmount. There are two acids, the _acetic_ and
_succinic_, that are composed of exactly the same number, and same kind
of atoms, and whose atomic weight is 6·25. The constituents of these
two acids are

               Atomic weight.
  2 atoms hydrogen  0·25
  4  "    carbon    3
  3  "    oxygen    3
                    ----
                    6·25

So that they consist of _nine_ atoms. Now as these two acids are
composed of the same number and the same kind of atoms, one would
expect that their properties should be the same; but this is not the
case: acetic acid has a strong and aromatic smell, succinic acid has
no smell whatever. Acetic acid is so soluble in water that it is
difficult to obtain it in crystals, and it cannot be procured in a
separate state free from water; for the crystals of acetic acid are
composed of one atom of acid and one atom of water united together; but
succinic acid is not only easily obtained free from water, but it is
not even very soluble in that liquid. The nature of the salts formed
by these two acids is quite different; the action of heat upon each
is quite different; the specific gravity of each differs. In short
all their properties exhibit a striking contrast. Now how are we to
account for this? Undoubtedly by the different ways in which the atoms
are arranged in each. If the electro-chemical theory of combination be
correct, we can only view atoms as combining two by two. A substance
then, containing nine atoms, such as acetic acid, must be of a very
complex nature. And it is obvious enough that these nine atoms might
arrange themselves in a great variety of binary compounds, and the way
in which these binary compounds unite may, and doubtless does, produce
a considerable effect upon the nature of the compound formed. Thus, if
we make use of Mr. Dalton's symbols to represent the atoms of hydrogen,
carbon and oxygen, we may suppose the nine atoms constituting acetic
and succinic acid to be arranged thus:

  [hydrogen][carbon][hydrogen]
  [oxygen][oxygen][oxygen]
  [carbon][carbon][carbon]

Or thus:

  [carbon][hydrogen][carbon]
  [oxygen][oxygen][oxygen]
  [carbon][hydrogen][carbon]

Now, undoubtedly these two arrangements would produce a great change in
the nature of the compound.

There is something in the vegetable acids quite different from the
acids of the inorganic kingdom, and which would lead to the suspicion
that the electro-chemical theory will not apply to them as it does to
the others. In the acids of carbon, sulphur, phosphorus, selenium, &c.,
we find one atom of a positive substance united to one, two, or three
of a negative substance: we are not surprised, therefore, to find the
acid formed negative also. But in acetic and succinic acids we find
every atom of oxygen united with two electro-positive atoms: the wonder
then is, that the acid should not only retain its electro-negative
properties, but that it should possess considerable power as an acid.
In benzoic acid, for every atom of oxygen, there are present no fewer
than seven electro-positive atoms.

Berzelius has returned to these analytical experiments repeatedly, so
that at last he has brought his results very near the truth indeed.
It is to his labours chiefly that the great progress which the atomic
theory has made is owing.

In the year 1814 there appeared in the Philosophical Transactions a
description of a Synoptical Scale of Chemical Equivalents, by Dr.
Wollaston. In this paper we have the equivalents or atomic weights
of seventy-three different bodies, deduced chiefly from a sagacious
comparison of the previous analytical experiments of others, and almost
all of them very near the truth. These numbers are laid down upon
a sliding rule, by means of a table of logarithms, and over against
them the names of the substances. By means of this rule a great many
important questions respecting the substances contained on the scale
may be solved. Hence the scale is of great advantage to the practical
chemist. It gives, by bare inspection, the constituents of all the
salts contained on it, the quantity of any other ingredient necessary
to decompose any salt, and the weights of the new constituents that
will be formed. The contrivance of this scale, therefore, may be
considered as an important addition to the atomic theory. It rendered
that theory every where familiar to all those who employed it. To
it chiefly we owe, I believe, the currency of that theory in Great
Britain; and the prevalence of the mode which Dr. Wollaston introduced,
namely, of representing the atom of oxygen by unity, or at least by
ten, which comes nearly to the same thing.

Perhaps the reader will excuse me if to the preceding historical
details I add a few words to make him acquainted with my own attempts
to render the atomic theory more accurate by new and careful analyses.
I shall not say any thing respecting the experiments which I undertook
to determine the specific gravity of the gases; though they were
performed with much care, and at a considerable expense, and though
I believe the results obtained approached accuracy as nearly as the
present state of chemical apparatus enables us to go. In the year
1819 I began a set of experiments to determine the exact composition
of the salts containing the different elementary bodies by means of
double decomposition, as was done by Wenzel, conceiving that in that
way the results would be very near the truth, while the experiments
would be more easily made. My mode was to dissolve, for example, a
certain weight of muriate of barytes in distilled water, and then to
ascertain by repeated trials what weight of sulphate of soda must be
added to precipitate the whole of the barytes without leaving any
surplus of sulphuric acid in the liquid. To determine this I put
into a watch-glass a few drops of the filtered liquor consisting of
the mixture of solutions of the two salts: to this I added a drop of
solution of sulphate of soda. If the liquid remained clear it was a
proof that it contained no sensible quantity of barytes. To another
portion of the liquid, also in a watch-glass, I added a drop of muriate
of barytes. If there was no precipitate it was a proof that the liquid
contained no sensible quantity of sulphuric acid. If there was a
precipitate, on the addition of either of these solutions, it showed
that there was an excess of one or other of the salts. I then mixed
the two salts in another proportion, and proceeded in this way till I
had found two quantities which when mixed exhibited no evidence of the
residual liquid containing any sulphuric acid or barytes. I considered
these two weights of the salts as the equivalent weights of the salt,
or as weights proportional to an integrant particle of each salt. I
made no attempt to collect the two new formed salts and to weigh them
separately.

I published the result of my numerous experiments in 1825, in a work
entitled "An Attempt to establish the First Principles of Chemistry by
Experiment." The most valuable part of this book is the account of the
salts; about three hundred of which I subjected to actual analysis. Of
these the worst executed are the phosphates; for with respect to them
I was sometimes misled by my method of double decomposition. I was not
aware at first, that, in certain cases, the proportion of acid in
these salts varies, and the phosphate of soda which I employed gave me
a wrong number for the atomic weight of phosphoric acid.




CHAPTER VII.

OF THE PRESENT STATE OF CHEMISTRY.


To finish this history it will be now proper to lay before the reader a
kind of map of the present state of chemistry, that he may be able to
judge how much of the science has been already explored, and how much
still remains untrodden ground.

Leaving out of view light, heat, and electricity, respecting the nature
of which only conjectures can be formed, we are at present acquainted
with fifty-three simple bodies, which naturally divide themselves
into three classes; namely, _supporters_, _acidifiable bases_, and
_alkalifiable bases_.

The supporters are oxygen, chlorine, bromine, iodine, and fluorine.
They are all in a state of negative electricity: for when compounds
containing them are decomposed by the voltaic battery they all attach
themselves to the positive pole. They have the property of uniting with
every individual belonging to the other two classes. When they combine
with the acidifiable bases in certain proportions they constitute
_acids_; when with the alkalifiable bases, _alkalies_. In certain
proportions they constitute _neutral_ bodies, which possess neither the
properties of acids nor alkalies.

The acidifiable bases are seventeen in number; namely, hydrogen, azote,
carbon, boron, silicon, sulphur, selenium, tellurium, phosphorus,
arsenic, antimony, chromium, uranium, molybdenum, tungsten, titanium,
columbium. These bodies do not form acids with every supporter, or
in every proportion; but they constitute the bases of all the known
acids, which form a numerous set of bodies, many of which are still
very imperfectly investigated. And indeed there are a good many of
them that may be considered as unknown. These acidifiable bases are
all electro-positive; but they differ, in this respect, considerably
from each other; hydrogen and carbon being two of the most powerful,
while titanium and columbium have the least energy. Sulphur and
selenium, and probably some other bodies belonging to this class are
occasional electro-negative bodies, as well as the supporters. Hence,
when united to other acidifiable bases, they produce a new class of
acids, analogous to those formed by the supporters. These have got
the name of sulphur acids, selenium acids, &c. Sulphur forms acids
with arsenic, antimony, molybdenum, and tungsten, and doubtless with
several other bases. To distinguish such acids from alkaline bases,
I have of late made an alteration in the termination of the old word
_sulphuret_, employed to denote the combination of sulphur with a base.
Thus _sulphide_ of arsenic means an acid formed by the union of sulphur
and arsenic; _sulphuret_ of copper means an alkaline body formed by the
union of sulphur and copper. The term _sulphide_ implies an _acid_, the
term _sulphuret_ a _base_. This mode of naming has become necessary,
as without it many of these new salts could not be described in an
intelligible manner. The same mode will apply to the acid and alkaline
compounds of selenium. Thus a _selenide_ is an acid compound, and a
_seleniet_ an alkaline compound in which selenium acts the part of a
supporter or electro-negative body. The same mode of naming might and
doubtless will be extended to all the other similar compounds, as soon
as it becomes necessary. In order to form a systematic nomenclature it
will speedily be requisite to new-model all the old names which denote
acids and bases; because unless this is done the names will become too
numerous to be remembered. At present we denote the alkaline bodies
formed by the union of _manganese_ and oxygen by the name of _oxides
of manganese_, and the acid compound of oxygen and the same metal
by the name of _manganesic acid_. The word _oxide_ applies to every
compound of a base and oxygen, whether neutral or alkaline; but when
the compound has acid qualities this is denoted by adding the syllable
_ic_ to the name of the base. This mode of naming answered tolerably
well as long as the acids and alkalies were all combinations of oxygen
with a base; but now that we know the existence of eight or ten classes
of acids and alkalies, consisting of as many supporters, or acidifiable
bases united to bases, it is needless to remark how very defective
it has become. But this is not the place to dwell longer upon such a
subject.

The alkalifiable bases are thirty-one in number; namely, potassium,
sodium, lithium, barium, strontium, calcium, magnesium, aluminum,
glucinum, yttrium, cerium, zirconium, thorium, iron, manganese, nickel,
cobalt, zinc, cadmium, lead, tin, bismuth, copper, mercury, silver,
gold, platinum, palladium, rhodium, iridium, osmium. The compounds
which these bodies form with oxygen, and the other supporters,
constitute all the alkaline bases or the substances capable of
neutralizing the acids.

Some of the acidifiable bases, when united to a certain portion of
oxygen, constitute, not acids, but _bases_ or _alkalies_. Thus the
_green oxides of chromium and uranium_ are alkalies; while, on the
other hand, there is a compound of oxygen and manganese which possesses
acid properties. In such cases it is always the compound containing the
least oxygen which is an alkali, and that containing the most oxygen
that is an acid.

The opinion at present universally adopted by chemists is, that the
ultimate particles of bodies consist of _atoms_, incapable of further
division; and these atoms are of a size almost infinitely small. It can
be demonstrated that the size of an atom of _lead_ does not amount to
so much as 1/888,492,000,000,000 of a cubic inch.

But, notwithstanding this extreme minuteness, each of these atoms
possesses a peculiar weight and a peculiar bulk, which distinguish it
from the atoms of every other body. We cannot determine the absolute
weight of any of them, but merely the relative weights; and this is
done by ascertaining the relative proportions in which they unite. When
two bodies unite in only one proportion, it is reasonable to conclude
that the compound consists of 1 atom of the one body, united to 1 atom
of the other. Thus oxide of bismuth is a compound of 1 oxygen and 9
bismuth; and, as the bodies unite in no other proportion, we conclude
that an atom of bismuth is nine times as heavy as an atom of oxygen. It
is in this way that the atomic weights of the simple bodies have been
attempted to be determined. The following table exhibits these weights
referred to oxygen as unity, and deduced from the best data at present
in our possession:

           Atomic weight.
  Oxygen        1
  Fluorine      2·25
  Chlorine      4·5
  Bromine      10
  Calcium       2·5
  Magnesium     1·5
  Aluminum      1·25
  Glucinum      2·25
  Iodine       15·75
  Hydrogen      0·125
  Azote         1·75
  Carbon        0·75
  Boron         1
  Silicon       1
  Phosphorus    2
  Sulphur       2
  Selenium      5
  Tellurium     4
  Arsenic       4·75
  Antimony      8
  Chromium      4
  Uranium      26
  Molybdenum    6
  Tungsten     12·5
  Titanium      3·25
  Columbium    22·75
  Potassium     5
  Sodium        3
  Lithium       0·75
  Barium        8·5
  Strontium     5·5
  Yttrium       4·25
  Zirconium     5
  Thorinum      7·5
  Iron          3·5
  Manganese     3·5
  Nickel        3·25
  Cobalt        3·25
  Cerium        6·25
  Zinc          4·25
  Cadmium       7
  Lead         13
  Tin           7·25
  Bismuth       9
  Copper        4
  Mercury      12·5
  Silver       13·75
  Gold         12·5
  Platinum     12
  Palladium     6·75
  Rhodium       6·75
  Iridium      12·25
  Osmium       12·5

The atomic weights of these bodies, divided by their specific gravity,
ought to give us the comparative size of the atoms. The following
table, constructed in this way, exhibits the relative bulks of these
atoms which belong to bodies whose specific gravity is known:

             Volume.

  Carbon       1
  Nickel  }    1·75
  Cobalt  }
  Manganese  }
  Copper     } 2
  Iron       }
  Platinum  }  2·6
  Palladium }
  Zinc         2·75
  Rhodium    }
  Tellurium  } 3
  Chromium   }
  Molybdenum   3·25
  Silica   }   3·5
  Titanium }
  Cadmium      3·75
  Arsenic    }
  Phosphorus } 4
  Antimony   }
  Tungsten  }
  Bismuth   }  4·25
  Mercury   }
  Tin      }   4·66
  Sulphur  }
  Selenium   } 5·4
  Lead       }
  Gold      }
  Silver    }  6
  Osmium    }
  Oxygen   }
  Hydrogen }   9·33
  Azote    }
  Chlorine }
  Uranium     13·5
  Columbium } 14
  Sodium    }
  Bromine     15·75
  Iodine      24
  Potassium   27


We have no data to enable us to determine the shape of these atoms. The
most generally received opinion is, that they are spheres or spheroids;
though there are difficulties in the way of admitting such an opinion,
in the present state of our knowledge, nearly insurmountable.

The probability is, that all the supporters have the property of
uniting with all the bases, in at least three proportions. But by
far the greater number of these compounds still remain unknown. The
greatest progress has been made in our knowledge of the compounds of
oxygen; but even there much remains to be investigated; owing, in a
great measure, to the scarcity of several of the bases which prevent
chemists from subjecting them to the requisite number of experiments.
The compounds of chlorine have also been a good deal investigated; but
bromine and iodine have been known for so short a time, that chemists
have not yet had leisure to contrive the requisite processes for
causing them to unite with bases.

The acids at present known amount to a very great number. The oxygen
acids have been most investigated. They consist of two sets: those
consisting of oxygen united to a single base, and those in which
it is united to two or more bases. The last set are derived from
the animal and vegetable kingdoms: it does not seem likely that the
electro-chemical theory of Davy applies to them. They must derive
their acid qualities from some electric principle not yet adverted to;
for, from Davy's experiments, there can be little doubt that they are
electro-negative, as well as the other acids. The acid compounds of
oxygen and a single base are about thirty-two in number. Their names are

  Hyponitrous acid
  Nitrous acid?
  Nitric acid
  Carbonic acid
  Oxalic acid
  Boracic acid
  Silicic acid
  Hypophosphorous acid
  Phosphorous acid
  Phosphoric acid
  Hyposulphurous acid
  Subsulphurous acid
  Sulphurous acid
  Sulphuric acid
  Hyposulphuric acid
  Selenious acid
  Selenic acid
  Arsenious acid
  Arsenic acid
  Antimonious acid
  Antimonic acid
  Oxide of tellurium
  Chromic acid
  Uranic acid
  Molybdic acid
  Tungstic acid
  Titanic acid
  Columbic acid
  Manganesic acid
  Chloric acid
  Bromic acid
  Iodic acid.

The acids from the vegetable and animal kingdoms (not reckoning a
considerable number which consist of combinations of sulphuric acid
with a vegetable or animal body), amount to about forty-three: so
that at present we are acquainted with very nearly eighty acids which
contain oxygen as an essential constituent.

The other classes of acids have been but imperfectly investigated.
Hydrogen enters into combination and forms powerful acids with all the
supporters except oxygen. These have been called hydracids. They are

  Muriatic acid, or hydrochloric acid
  Hydrobromic acid
  Hydriodic acid
  Hydrofluoric acid, or fluoric acid
  Hydrosulphuric acid
  Hydroselenic acid
  Hydrotelluric acid

These constitute (such of them as can be procured) some of the most
useful and most powerful chemical reagents in use. There is also
another compound body, _cyanogen_, similar in its characters to a
supporter: it also forms various acids, by uniting to hydrogen,
chlorine, oxygen, sulphur, &c. Thus we have

  Hydrocyanic acid
  Chlorocyanic acid
  Cyanic acid
  Sulpho-cyanic acid, &c.

We know, also, fluosilicic acid and fluoboric acids. If to these we
add fulminic acid, and the various sulphur acids already investigated,
we may state, without risk of any excess, that the number of acids at
present known to chemists, and capable of uniting to bases, exceeds a
hundred.

The number of alkaline bases is not, perhaps, so great; but it must
even at present exceed seventy; and it will certainly be much augmented
when chemists turn their attention to the subject. Now every base is
capable of uniting with almost every acid,[9] in all probability in at
least three different proportions: so that the number of _salts_ which
they are capable of forming cannot be fewer than 21,000. Now scarcely
1000 of these are at present known, or have been investigated with
tolerable precision. What a prodigious field of investigation remains
to be traversed must be obvious to the most careless reader. In such
a number of salts, how many remain unknown that might be applied to
useful purposes, either in medicine, or as mordants, or dyes, &c. How
much, in all probability, will be added to the resources of mankind by
such investigations need not be observed.

 [9] Acids and bases of the same class all unite. Thus sulphur acids
 unite with sulphur bases; oxygen acids with oxygen bases, &c.

The animal and vegetable kingdoms present a still more tempting field
of investigation. Animal and vegetable substances may be arranged
under three classes, acids, alkalies, and neutrals. The class of acids
presents many substances of great utility, either in the arts, or for
seasoning food. The alkalies contain almost all the powerful medicines
that are drawn from the vegetable kingdom. The neutral bodies are
important as articles of food, and are applied, too, to many other
purposes of first-rate utility. All these bodies are composed (chiefly,
at least) of hydrogen, carbon, oxygen, and azote; substances easily
procured abundantly at a cheap rate. Should chemists, in consequence
of the knowledge acquired by future investigations, ever arrive at the
knowledge of the mode of forming these principles from their elements
at a cheap rate, the prodigious change which such a discovery would
make upon the state of society must be at once evident. Mankind would
be, in some measure, independent of climate and situation; every thing
could be produced at pleasure in every part of the earth; and the
inhabitants of the warmer regions would no longer be the exclusive
possessors of comforts and conveniences to which those in less favoured
regions of the earth are strangers. Let the science advance for
another century with the same rapidity that it has done during the
last fifty years, and it will produce effects upon society of which
the present race can form no adequate idea. Even already some of
these effects are beginning to develop themselves;--our streets are
now illuminated with gas drawn from the bowels of the earth; and the
failure of the Greenland fishery during an unfortunate season like the
last, no longer fills us with dismay. What a change has been produced
in the country by the introduction of steam-boats! and what a still
greater improvement is at present in progress, when steam-carriages
and railroads are gradually taking the place of horses and common
roads. Distances will soon be reduced to one-half of what they are at
present; while the diminished force and increased rate of conveyance
will contribute essentially to lower the rest of our manufactures, and
enable us to enter into a successful competition with other nations.

I must say a few words upon the application of chemistry to physiology
before concluding this imperfect sketch of the present state of the
science. The only functions of the living body upon which chemistry
is calculated to throw light, are the processes of digestion,
assimilation, and secretion. The nervous system is regulated by laws
seemingly quite unconnected with chemistry and mechanics, and, in
the present state of our knowledge, perfectly inscrutable. Even in
the processes of digestion, assimilation, and secretion, the nervous
influence is important and essential. Hence even of these functions
our notions are necessarily very imperfect; but the application of
chemistry supplies us with some data at least, which are too important
to be altogether neglected.

The food of man consists of solids and liquids, and the quantity of
each taken by different individuals is so various, that no general
average can be struck. I think that the drink will, in most cases,
exceed the solid food in nearly the proportion of 4 to 3; but the solid
food itself contains not less than 7-10ths of its weight of water. In
reality, then, the quantity of liquid taken into the stomach is to that
of solid matter as 10 to 1. The food is introduced into the mouth,
comminuted by the teeth, and mixed up with the saliva into a kind of
pulp.

The saliva is a liquid expressly secreted for this purpose, and the
quantity certainly does not fall short of ten ounces in the twenty-four
hours: indeed I believe it exceeds that amount: it is a liquid almost
as colourless as water, slightly viscid, and without taste or smell:
it contains about 3/1000 of its weight of a peculiar matter, which is
transparent and soluble in water: it has suspended in it about 1·4/1000
of its weight of mucus; and in solution, about 2·8/1000 of common salt
and soda: the rest is water.

From the mouth the food passes into the stomach, where it is changed
to a kind of pap called chyme. The nature of the food can readily be
distinguished after mastication; but when converted into _chyme_, it
loses its characteristic properties. This conversion is produced by
the action of the eighth pair of nerves, which are partly distributed
on the stomach; for when they are cut, the process is stopped: but
if a current of electricity, by means of a small voltaic battery, be
made to pass through the stomach, the process goes on as usual. Hence
the process is obviously connected with the action of electricity. A
current of electricity, by means of the nerves, seems to pass through
the food in the stomach, and to decompose the common salt which is
always mixed with the food. The muriatic acid is set at liberty, and
dissolves the food; for _chyme_ seems to be simply a solution of the
food in muriatic acid.

The chyme passes through the pyloric orifice of the stomach into the
duodenum, the first of the small intestines, where it is mixed with two
liquids, the bile, secreted by the liver, and the pancreatic juice,
secreted by the pancreas, and both discharged into the duodenum to
assist in the further digestion of the food. The chyme is always acid;
but after it has been mixed with the bile, the acidity disappears. The
characteristic constituent of the bile is a bitter-tasted substance
called _picromel_, which has the property of combining with muriatic
acid, and forming with it an insoluble compound. The pancreatic juice
also contains a peculiar matter, to which chlorine communicates a red
colour. The use of the pancreatic juice is not understood.

During the passage of the chyme through the small intestines it is
gradually separated into two substances; the _chyle_, which is absorbed
by the lacteals, and the excrementitious matter, which is gradually
protruded along the great intestines, and at last evacuated. The chyle,
in animals that live on vegetable food, is semitransparent, colourless,
and without smell; but in those that use animal food it is white,
slightly similar to milk, with a tint of pink. When left exposed to
the air it coagulates as blood does. The coagulum is _fibrin_. The
liquid portion contains _albumen_, and the usual salts that exist in
the blood. Thus the chyle contains two of the constituents of blood;
namely, _albumen_, which perhaps may be formed in the stomach, and
_fibrin_, which is formed in the small intestines. It still wants the
third constituent of blood, namely, the _red_ globules.

From the lacteals the chyle passes into the thoracic duct; thence into
the left subclavian vein, by which it is conveyed to the heart. From
the heart it passes into the lungs, during its circulation through
which the _red globules_ are supposed to be formed, though of this we
have no direct evidence.

The lungs are the organs of _breathing_, a function so necessary
to hot-blooded animals, that it cannot be suspended, even for a
few minutes, without occasioning death. In general, about twenty
inspirations, and as many expirations, are made in a minute. The
quantity of air which the lungs of an ordinary sized man can contain,
when fully distended, is about 300 cubic inches. But the quantity
actually drawn in and thrown out, during ordinary inspirations and
expirations, amounts to about sixteen cubic inches each time.

In ordinary cases the volume of air is not sensibly altered by
respiration; but it undergoes two remarkable changes. A portion of its
oxygen is converted into carbonic acid gas, and the air expired is
saturated with humidity at the temperature of 98°. The moisture thus
given out amounts to about seven ounces troy, or very little short
of half an avoirdupois pound. The quantity of carbonic acid formed
varies much in different individuals, and also at different times in
the day; being a maximum at twelve o'clock at noon, and a minimum at
midnight. Perhaps four of carbonic acid, in every 100 cubic inches of
air breathed, may be a tolerable approach to the truth; that is to say,
that every six respirations produce four cubic inches of carbonic acid.
This would amount to 19,200 cubic inches in twenty-four hours. Now
the weight of 19,200 cubic inches of carbonic acid gas is 18·98 troy
ounces, which contain rather more than five troy ounces of carbon.

These alterations in the air are doubtless connected with
corresponding alterations in the blood, though with respect to the
specific nature of these alterations we are ignorant. But there
are two purposes which respiration answers, the nature of which we
can understand, and which seem to afford a reason why it cannot be
interrupted without death. It serves to develop the _animal heat_,
which is so essential to the continuance of life; and it gives the
blood the property of stimulating the heart; without which it would
cease to contract, and put an end to the circulation of the blood.
This stimulating property is connected with the scarlet colour which
the blood acquires during respiration; for when the scarlet colour
disappears the blood ceases to stimulate the heart.

The temperature of the human body in a state of health is about 98°
in this country; but in the torrid zone it is a little higher. Now as
we are almost always surrounded by a medium colder than 98°, it is
obvious that the human body is constantly giving out heat; so that
if it did not possess the power of generating heat, it is clear that
its temperature would soon sink as low as that of the surrounding
atmosphere.

It is now generally understood that common combustion is nothing else
than the union of oxygen gas with the burning body. The substances
commonly employed as combustibles are composed chiefly of carbon and
hydrogen. The heat evolved is proportional to the oxygen gas which
unites with these bodies. And it has been ascertained that every 3¾
cub¾ic inches of oxygen which combine with carbon or hydrogen occasion
the evolution of 1° of heat.

There are reasons for believing that not only carbon but also hydrogen
unite with oxygen in the lungs, and that therefore both carbonic acid
and water are formed in that organ. And from the late experiments
of M. Dupretz it is clear that the heat evolved in a given time, by
a hot-blooded animal, is very little short of the heat that would be
evolved by the combustion of the same weight of carbon and hydrogen
consumed during that time in the lungs. Hence it follows that the heat
evolved in the lungs is the consequence of the union of the oxygen of
the air with the carbon and hydrogen of the blood, and that the process
is perfectly analogous to combustion.

The specific heat of arterial blood is somewhat greater than that of
venous blood. Hence the reason why the temperature of the lungs does
not become higher by breathing, and why the temperature of the other
parts of the body are kept up by the circulation.

The blood seems to be completed in the kidneys. It consists essentially
of albumen, fibrin, and the red globules, with a considerable quantity
of water, holding in solution certain salts which are found equally
in all the animal fluids. It is employed during the circulation in
supplying the waste of the system, and in being manufactured into all
the different secretions necessary for the various functions of the
living body. By these different applications of it we cannot doubt that
its nature undergoes very great changes, and that it would soon become
unfit for the purposes of the living body were there not an organ
expressly destined to withdraw the redundant and useless portions of
that liquid, and to restore it to the same state that it was in when
it left the lungs. These organs are the _kidneys_; through which all
the blood passes, and during its circulation through which the urine is
separated from it and withdrawn altogether from the body. These organs
are as necessary for the continuance of life as the lungs themselves;
accordingly, when they are diseased or destroyed, death very speedily
ensues.

The quantity of urine voided daily is very various; though, doubtless,
it bears a close relation to that of the drink. It is nearly but not
quite equal to the amount of the drink; and is seldom, in persons who
enjoy health, less than 2 lbs. avoirdupois in twenty-four hours. Urine
is one of the most complex substances in the animal kingdom, containing
a much greater number of ingredients than are to be found in the blood
from which it is secreted.

The water in urine voided daily amounts to about 1·866lbs. The blood
contains no acid except a little muriatic. But in urine we find
sulphuric, phosphoric, and uric acids, and sometimes oxalic and nitric
acids, and perhaps also some others. The quantity of sulphuric acid
may be about forty-eight grains daily, containing nineteen grains of
sulphur. The phosphoric acid about thirty-three grains, containing
about fourteen grains of phosphorus. The uric acid may amount to
fourteen grains. These acids are in combination with potash, or soda,
or ammonia, and also with a very little lime and magnesia. The common
salt evacuated daily in the urine amounts to about sixty-two grains.
The urea, a peculiar substance found only in the urine, amounts perhaps
to as much as 420 grains.

It would appear from these facts that the kidneys possess the property
of converting the sulphur and phosphorus, which are known to exist in
the blood, into acids, and likewise of forming other acids and urea.

The quantity of water thrown out of the system by the urine and lungs
is scarcely equal to the amount of liquid daily consumed along with the
food. But there is another organ which has been ascertained to throw
out likewise a considerable quantity of moisture, this organ is the
skin; and the process is called _perspiration_. From the experiments of
Lavoisier and Seguin it appears that the quantity of moisture given out
daily by the skin amounts to 54·89 ounces: this added to the quantity
evolved from the lungs and the urine considerably exceeds the weight of
liquid taken with the food, and leaves no doubt that water as well as
carbonic acid must be formed in the lungs during respiration.

Such is an imperfect sketch of the present state of that department of
physiology which is most intimately connected with Chemistry. It is
amply sufficient, short as it is, to satisfy the most careless observer
how little progress has hitherto been made in these investigations; and
what an extensive field remains yet to be traversed by future observers.


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Transcriber's Notes

Obvious typographical errors have been silently corrected. Other
variations in spelling and punctuation remain unchanged.

Several elements are represented by symbols in the original. They have
been replaced by the name of the element within [] thus - [hydrogen].

In chapter VI the final numeral in several of the decimal numbers is
surmounted by a point. These are shown thus 1·111[.1].

Italics are represented thus _italic_.





End of the Project Gutenberg EBook of The History of Chemistry, Vol II (of 2), by 
Thomas Thomson

*** 