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                           GETTING & GOLD.




                   GRIFFIN’S STANDARD PUBLICATIONS.


            Fourth Edition, Revised. Fully Illustrated. 21s.

    =THE METALLURGY OF GOLD=. By T. KIRKE ROSE, D.Sc. Lond.,
    Assoc. R.S.M., Chemist and Assayer to the Royal Mint.

    “Adapted for all who are interested in the Gold Mining Industry,
    being free from technicalities as far as possible, but is more
    particularly of value to those engaged in the industry.”--_Cape
    Times._

     “A Comprehensive Practical Treatise on this important
     subject.”--_The Times._

                      *       *       *       *       *

    Medium 8vo. With numerous Plates, Maps, and Illustrations. 21s. net.

    =CYANIDING GOLD AND SILVER ORES=: A Practical Treatise on the Cyanide
      Process. By H. FORBES JULIAN, and EDGAR SMART, A.M.I.C.E.

    “A handsome volume of 400 pages which will be a valuable book of
    reference for all associated with the process.”--_Mining Journal._

                      *       *       *       *       *

    Large Crown 8vo. Third English Edition. Fully Illustrated, 7s. 6d.

    =THE CYANIDE PROCESS OF GOLD EXTRACTION=. By Professor JAMES PARK,
      F.G.S., M.Inst.M.M.

    “We can confidently recommend this book as a thoroughly
    practical work, and congratulate the author at its continued
    success.”--_Chemical News._

                      *       *       *       *       *

    In Crown 8vo. Illustrated. Fancy Cloth Boards. Price 4s. 6d.

    =GOLD SEEKING IN SOUTH AFRICA=; A Handbook of Hints for intending
      Explorers, Prospectors, and Settlers. By THEO. KASSNER, Mine
      Manager.

    “The Prospector ought to include this book in his library of
    reference, and the stay-at-home reader will be interested and
    informed by its contents.”--_Mining World._

                      *       *       *       *       *

    Third Edition, Revised. With Illustrations. Handsome cloth, 5s.

    =PROSPECTING FOR MINERALS=. By S. HERBERT COX, Assoc. R.S.M., M.Inst.
      M.M., F.G.S., &c.

    “This EXCELLENT HANDBOOK will prove a perfect _vade-mecum_
    to those engaged in the practical work of Mining and
    Metallurgy.”--_Times of Africa._

                      *       *       *       *       *

    Large 8vo. Cloth. Fully Illustrated. 12s. 6d. net.

    =METALLURGICAL ANALYSIS AND ASSAYING=: A THREE YEARS’ COURSE FOR
      STUDENTS OF SCHOOLS OF MINES. By W. A. MACLEOD, B.A., B.Sc.,
      A.O.S.M., and CHAS. WALKER, F.C.S.

    “The publication of this volume tends to prove that the teaching
    of metallurgical analysis and assaying in Australia rests in
    competent hands.”--_Nature._

                      *       *       *       *       *

    In Large 4to. Library Style. Beautifully Illustrated with 20
    Plates, many in Colours, and 94 Figures in the Text. £2, 2s. net.

    =PRECIOUS STONES=: THEIR PROPERTIES, OCCURRENCES, AND USES. By Dr. MAX
      BAUER. Translated by L. J. SPENCER, M.A. (Cantab.), F.G.S.

    “The plates are remarkable for their beauty, delicacy, and
    truthfulness. A glance at them alone is a lesson on precious
    stones.”--_Athenæum._

                      *       *       *       *       *

    London: CHARLES GRIFFIN & CO., Limited, Exeter St., Strand.

    [Illustration: THE PROSPECTOR.--DISHWASHING OR PANNING
    _Frontispiece_]




                          =GETTING GOLD=:




                      =A PRACTICAL TREATISE=
                                FOR
                =PROSPECTORS, MINERS, AND STUDENTS=.

                                 BY

                      =J. C. F. JOHNSON, F.G.S.,=
             MEMBER OF THE AUST. INST. OF MINING ENGINEERS;
      AUTHOR OF “PRACTICAL MINING,” “THE GENESIOLOGY OF GOLD,” ETC.


                           =THIRD EDITION.=


                 _=WITH 50 ILLUSTRATIONS AND 8 PLATES.=_


          [Illustration: CHARLES GRIFFIN AND COMPANY LIMITED 1820]


                                LONDON:
                 CHARLES GRIFFIN AND COMPANY, Limited;
                         EXETER STREET, STRAND.
                                 1904.

                        [_All rights reserved._]

                    *       *       *       *       *




    PREFACE TO THE FIRST EDITION


Some years ago the author published a small book entitled “Practical
Mining,” designed specially for the use of those engaged in the always
fascinating, though not as invariably profitable, pursuit of “Getting
Gold.” Of this ten thousand copies were sold, nearly all in Australasia,
and the work is now out of print. The London _Mining Journal_ of
September 9th, 1891, said of it: “We have seldom seen a book in which so
much interesting matter combined with useful information is given in so
small a space.”

The gold-mining industry has grown considerably since 1891, and it
appeared to the writer that the present would be a propitious time to
bring out a similar work, but with a considerably enlarged scope. What
has been aimed at is to make “Getting Gold” a compendium, in specially
concrete form, of useful information respecting the processes of winning
from the soil and the after-treatment of gold and gold ores, including
some original practical discoveries by the author. Practical
information, original and selected, is given to mining company
directors, mine managers, quartz mill operators, and prospectors. In
“Rules of Thumb,” chapters XI. and XII., will be found a large number
of useful hints on subjects directly and indirectly connected with
gold-mining.

The author’s mining experience extends back thirty years and he
therefore ventures to believe with some degree of confidence that the
information, original or compiled, which the book contains, will be
found both useful and profitable to those who are in any capacity
interested in the gold-mining industry.

                                            J. C. F. J.

    London, _November_ 1896.

                      *       *       *       *       *




    PUBLISHERS’ NOTE TO THE THIRD EDITION


The reviewer in _Nature_ remarked on the First Edition of this book,
“It has often been said that _the practical man_ does not write books,
but There Is Here a Complete Refutation of the Calumny.” The sale of
two large editions has justified the opinion of the reviewer, and shows
that the book from the practical man is valued. The Third Edition has
been revised throughout and several new figures in the text and eight
full-page plates have been added. It is confidently hoped that this new
Edition will meet with the same kindly reception as the earlier ones.

    _November_ 1904.




    CONTENTS


    CHAPTER I

    INTRODUCTORY. GETTING GOLD

  Gold--Poetical and historical references--Its wide
    distribution--Remains of ancient works--Old appliances--Modern
    appliances anticipated--Labours of alchemists--Deposition
    similar to common minerals--How first obtained--The Pactolian
    annual miracle--Mode of working auriferous sand and
    lodes--Principal sources of gold supply--Transvaal
    production--Californian production--Real date of discovery in
    Australia--State encouragement for new discoveries--Obstacles
    in early Australian production--Australasian production to
    date--The world’s wealth--Nuggets--Modern methods--Hydraulicing
    cheapest--Definition of “lode”--Igneous and aqueous theories
    contrasted--Difference between reef and alluvial gold--Mining
    terms explained--Usual exploitation and
    treatment--Operations--Stamp battery--Its advantages as
    crusher--Usual milling operations                              pp. 1-12


    CHAPTER II

    GOLD PROSPECTING

    (ALLUVIAL AND GENERAL)

  Ignorance of prospectors--Chapter specially addressed to the
    inexperienced--Valuable finds mostly accidents--Best way to
    obtain elementary knowledge--An assaying experience--What a
    prospector should know--Usual geological conditions of most
    minerals--Unwise to follow theories blindly--Instances of
    unlikely occurrences of gold--Importance of examining
    outcrops--Curious matrices for gold--Alluvial and reef
    gold--Hints to prospectors--Prospecting for alluvial
    gold--Tin dish--Dry blowing--Size of prospecting
    shaft--Intricacy of deep leads--How to recognise true
    bottom--Gold bearing “gutters”--Difference in working
    shallow and wet ground                                        pp. 13-21


    CHAPTER III

    LODE OR REEF PROSPECTING

  Likeliest localities for reefs--Similarity of indications of
    minerals--Where first prospecting is done--A practical
    example--Ironstone “blows”--Their true origin--Igneous theory
    untenable--Usual trend of lodes in Australia--Exceptions
    to the rule--Instances of rich deposits apart from
    lodes--Sinuosity of lodes--How to trace lodes
    demonstrated--Examine all indications--How to recognise gold,
    silver, copper, tin--How to ascertain their value--Caution
    in sinking--Where to prospect in case of parallel lodes--Usual
    underlie in Australia--Size of prospecting shaft--Tip for
    mullock--How to distinguish gold from pyrites or
    mica--Estimating value from prospect--How to pan--An
    amalgamating assay method--Author’s device when antimony
    present--Battery, best test--Silver and tin indications--Lode
    tin, stream tin, difficulty of recognising tin--Lode tin
    always near granite--Minerals often mistaken for tin--How
    to discriminate--Tin in Westralia                             pp. 22-33


    CHAPTER IV

    THE GENESIOLOGY OF GOLD

    (AURIFEROUS LODES)

  Igneous theory formerly strongly upheld--Quotation from
    Rosales--His  arguments combated--Hydro-thermal action--Its
    evidences in New Zealand--Professor Lobley’s theory--Author’s
    deposition theory confirmed--Later works--Conclusions of
    Le Conte--Metamorphic slates and earlier Silurian strata
    theory--Format ion of mineral lodes--What was gold
    originally?--Metal or metallic salt--Silicate hypothesis
    preferred--Explanation of sulphides and silicates of
    gold--Bischof’s interesting experiment--Skey’s and other
    deposition experiments--How gold took its metallic form--The
    Comstock lode--Occurrence of gold in shutes explained--Why
    lode junctions are usually rich--Cox’s theory--Instances
    of lodes re-forming--Gold as natural sulphide--Newbery’s
    theory of gold in pyritous lodes--Probable occurrence in
    pyritous ores as sulphide                                     pp. 34-47


    CHAPTER V

    THE GENESIOLOGY OF GOLD

    (AURIFEROUS DRIFTS)

  Derivation and occurrence--Old diggers’ “growing”
    theory--Deposition experiment illustrating nature--Denudation
    of quartz lodes theory--Examples of its probability--Nuggets
    require other explanation--Deposition, most rational
    theory--Usual alluvial theory combated--Daintree’s and
    Wilkinson’s deposition experiments--Spondulix and Lothair
    nuggets--Newbery’s deposition experiments--Nugget form
    explained--Author’s experiments in manufacture of golden
    quartz--Extract from author’s “Deposition of
    Gold”--Remarkable nugget--Reason of superiority of alluvial
    gold                                                          pp. 48-58


    CHAPTER VI

    GOLD EXTRACTION

  Division of methods of treating ores--Scientific extraction
    indispensable--Superficial knowledge--German and Australian
    methods compared--Schools of Mines--Antiquity of gold
    working--Miner’s equipment--Tub, cradle, long tom--How
    operated--Hydraulic mining--Extensive Australian
    drifts--Extraction of reef gold--Amalgamation--Crushing
    appliances--Preference for stampers--The Lemichel
    syphon--The Griffin mill--The Huntingdon mill--Dodge
    crusher--Krupp Grusonwerk Ball Mill--Premature plant
    erecting--Danger of untried processes--Double faulted
    lode--Automatic ore feeders--Machinery site--Foundations
    for battery--Weight of stamps--Power and water required
    for battery--Selection of screen--Fall of tables--Ancient
    Egyptian gold washing table--Blanket tables--Successful
    treatment of refractory ore in Australia--Methods vary
    with ore--Importance of even crushing--Points _re_
    crushing--Best form of stamper box--Cleaning plates--Form
    of scraper--Retorting amalgam--Special difficulties, how
    to overcome them                                              pp. 59-86


    CHAPTER VII

    GOLD EXTRACTION

    (SECONDARY PROCESSES AND LIXIVIATION)

  Choosing the plant---Various ores and their
    constituents--Amalgamation--Various concentrators--Percussion
    tables--Frue vanner--Pan concentration--Simultaneous grinding
    and amalgamating condemned--Watson and Denny pan--Good
    machines often condemned--Procedure in ore treatment--Duncan
    pan--Calcining--Rotatory amalgamator--Steaming
    concentrates--Dry amalgamation--Sulphuric acid and sickened
    mercury--Amalgamation without overflow--Experiments--Steam
    as an agent in gold extraction--Lixiviation by
    chlorine--Various processes--Mount Morgan--Cyanide process    pp. 87-99


    CHAPTER VIII

    CALCINATION OR “ROASTING” OF ORES

  Effect of roasting--Various methods--Reverberatory
    furnaces--Howell, White, Brückner, Thwaite-Denny, and
    Molesworth types of revolving cylinder furnaces--Shaft
    type--The Stetefeldt furnace--Chimneys--Depositing chambers pp. 100-108


    CHAPTER IX

    MOTOR POWER AND ITS TRANSMISSION

  Water and steam power--Waterless power plant described--Oil
      engines--Electric transmission--Advantages of electric
      power--Its possibilities                                  pp. 109-112


    CHAPTER X

    COMPANY FORMATION AND OPERATIONS

  Mining becoming a scientific business--Initial mistakes in
    public companies--Self-styled mining experts--How articles
    of association are compiled--How directors and officials
    are chosen--The usual consequences--Remedies--State
    inspectors--Certificates for mine managers--Directors--
    Specialists in various branches advisable--Qualifications
    of mine managers--Economic advantages of co-operation--Joint
    central extraction works--Folly of adopting untried new
    processes without full knowledge--Pertinent
    quotation--Warning to directors--Robbing mills--How
    prevented--Conclusion                                       pp. 113-126


    CHAPTER XI

    RULES OF THUMB

  Living places--A bush bed--Northern Territory
    hammock--Purifying water--To obtain water from roots--An
    effective filter--Canvas water-bag--Medicine case--Producing
    fire--To copy correspondence--Simple telegraphic code--A
    serviceable soap--To cross a flooded stream--To make a hide
    bucket--To make a “slush lamp”                              pp. 127-139


    CHAPTER XII

    RULES OF THUMB

    (MINING APPLIANCES AND METHODS)

  A temporary forge--Making charcoal--Rough smelting on the
    mine--Misfires in blasting--To prevent loss of rich
    specimens in blasting--Simple retorting of small quantities
    of amalgam--Simple mode of ascertaining nominal H.-P. of
    engine--Scaling copper plates--How to supply mercury and
    water to mortar-boxes--Power for mills--To avoid loss in
    cleaning up--Iron extractor--To silver copper plates--How to
    make a dolly, rough windlass, puddler--A makeshift
    pump--Squeezing amalgam--Sluice plates--Measuring inaccessible
    distances--To set out a right angle with tape--Simple levelling
    instruments--Levelling by aneroid barometer--To determine
    heights--To find depth of shaft--Plan for re-using
    water--Cooling compound for heated bearing--Cleaning greasy
    plummer blocks--An excellent anti-friction compound--To
    clean brass--A solvent for rust--To protect iron and steel
    from rust--To keep machinery from rusting--Fire-lute--
    Rope-splicing                                               pp. 140-166


    APPENDIX


    1. SELECTED DATA FOR MINING MEN.

  To find lost part of a vein--Calculation of ore
    reserves--Hydraulics--Boring--Durability of ropes--Diamond
    drilling--Notes on timber--Laying out areas--Mensuration--Mine
    surveying problems--Rainfall--Belting notes--Weight and bulk of
    materials--Chemical elements and their symbols, &c.--Common
    names of chemical substances--Thermometer readings--Freezing,
    fusing, and boiling points--Heat values of fuels--Signs and
    symbols used in expressing formulas--Weights and measures--To
    find contents of a tank--Sizes and weights of corrugated iron
    sheets--Thickness and weight of sheet iron--Qualities of
    ropes--Atmosphere--Fresh and salt water--Velocity of falling
    fluids--Pressure of water--Table of squares and cubes, and
    their roots--Wages and interest tables.                     pp. 167-193


    2. AUSTRALASIAN MINING REGULATIONS                          pp. 194-201


    INDEX                                                       pp. 203-206




    GETTING GOLD




    CHAPTER I

    INTRODUCTORY


Gold is a name to charm by. It is desired by all nations, and is the one
metal the supply of which never exceeds the demand. Some one has aptly
said, “Gold is the most potent substance on the surface of our planet.”
Tom Hood sings:

    Gold, gold, gold, gold!
    Bright and yellow, hard and cold;
    Molten, graven, hammered, rolled,
    Heavy to get, and light to hold;
    Stolen, borrowed, squandered, doled.

That this much appreciated metal is heavy to get is proved by the high
value which has been placed on it from times remote to date, and that it
is light to hold most of us know to our cost.

We read no farther than the second chapter in the Bible when we find
mention of gold. There Moses speaks of “the land of Havilah, where there
is gold”; and in Genesis, chapter xxiv., we read that Abraham’s servant
gave Rebekah an earring of half a shekel weight, say 4 dwt. 13 grs., and
“two bracelets of ten shekels weight,” or about 4½ ozs. Then
throughout the Scriptures, and, indeed, in all historic writings, we
find frequent mention of the king of metals, and always it is spoken of
as a commodity highly prized.

I have sometimes thought, however, that either we are mistaken in the
weights used by the Hebrew nation in early days, or that the arithmetic
of those times was not quite “according to Cocker.” We read, I. Kings x.
and xli., that Solomon in one year received no less than six hundred and
three score and six talents of gold. If a talent of gold was, as has
been assumed, 3000 shekels of 219 grains each, the value of the golden
treasure accumulated in this one year by the Hebrew king would have been
£3,646,350 sterling. Considering that the only means of “getting gold”
in those days was a most primitive mode of washing it from river sands,
or a still more difficult and laborious process of breaking the quartz
from the lode without proper tools or explosives, and then slowly
grinding it by hand labour between two stones, the amount mentioned is
truly enormous.

Of this treasure the Queen of Sheba, who came to visit the Hebrew
monarch, contributed a hundred and twenty talents, or, say, £600,000
worth. Where the Land of Ophir, whence this golden lady came, was really
situated has evoked much controversy, but there is now a general opinion
that Ophir was on the east coast of Africa, somewhere near Delagoa Bay,
in the neighbourhood of the Limpopo and Sabia rivers. It should be
mentioned that the name of the “black but comely” queen was Sabia, which
may or may not be a coincidence, but it is certainly true that the
rivers of this district have produced gold from prehistoric times till
now.

The discovery of remarkable ruins in the newly acquired province of
Mashonaland, which evince a high state of civilisation in the builders,
may throw some light on this interesting subject.

The principal value of gold is as a medium of exchange, and its high
appreciation is due, first, to the fact that it is in almost universal
request; and, secondly, to its comparative scarcity; yet, oddly enough,
with the exception of that humble but serviceable metal iron, gold is
the most widely distributed metal known. Few, if any, countries do not
possess it, and in most parts of the world, civilised and uncivilised,
it is mined for and brought to market. The torrid, temperate, and frigid
zones are almost equally auriferous. Siberia, mid-Asia, most parts of
Europe, down to equatorial and southern Africa in the Old World, and
north, central, and southern America, with Australasia, in what may be
termed the New World, are all producers of gold in payable quantities.

In the earlier ages, the principal source of the precious metal was
probably Africa, which has always been prolific in gold. To this day
there are to be seen in the southern provinces of Egypt excavations and
the remains of old mine buildings and appliances left by the ancient
gold-miners, who were mostly State prisoners. Some of these mines were
worked by the Pharaohs of, and before, the time of Moses; and in these
dreadful places thousands of Israelites were driven to death by the
taskmaster’s whip. Amongst the old appliances is one cut out of stone
very similar to the amalgamating, or blanket-table, of a modern quartz
mill (_see_ p. 79).

The grinding was done between stones, and possibly by means of such
primitive mechanism as is used to-day by the natives of Korea.

    [Illustration: FIG. 1. KOREAN MILL.]

The Korean Mill is simply a large hard stone shaped as in Fig. 1, to
which a rocking motion is given by manual power by means of the bamboo
handles while the ore is crushed between the upper and basement stone.

Solomon says “there is no new thing under the sun”; certainly there is
much that is not absolutely new in appliances for gold extraction. I
lately learned that the principle of one of our newest concentrating
machines, the Frue vanner, was known in India and the East centuries
ago; and we have it on good authority--that of Pliny--that gold saving
by amalgamation with mercury was practised before the Christian era. It
will not be surprising then if, ere long, some one claims to have
invented the Korean Mill, with improvements.

Few subjects in mineralogical science have evoked more controversy than
the origin of gold. In the Middle Ages, and, indeed, down to the time of
that great philosopher, Sir Isaac Newton, who was himself bitten with
the craze, it was widely believed that, by what was known as
transmutation, the baser metals might be changed to gold; and much time
and trouble were expended in attempts to make gold--needless to say
without the desired result. Doubtless, however, many valuable additions
to chemical science, and also some useful metallic alloys, were thus
discovered.

The latest startling statement on this subject comes from, of course,
the wonderland of the world, America. In a recently published journal it
is said that a scientific metallurgist there has succeeded in producing
absolutely pure gold, which stands all tests, from silver. Needless to
say, if this were true, at all events the much vexed bi-metallic
question would be solved at once and for all time.

It is now admitted by all specialists that the royal metal, though
differing in material respects in its mode of occurrence from its useful
but more plebeian brethren of the mineral kingdom, has yet been
deposited under similar conditions from mineral salts held in solution.

The first mode of obtaining this much desired metal was doubtless by
washing the sand of rivers which flowed through auriferous strata. Some
of these, such as the Lydian stream, Pactolus, were supposed to renew
their golden stores miraculously each year. What really happened was
that the winter floods detached portions of auriferous drift from the
banks, which, being disintegrated by the rush and flow of the water,
would naturally deposit in the still reaches and eddies any gold that
might be contained therein.

The mode of washing was exactly that carried on by the natives in some
districts of Africa to-day. A wooden bowl was partly filled with
auriferous sand and mud, and, standing knee-deep in the stream, the
operator added a little water, and caused the contents of the bowl to
take a circular motion, somewhat as the modern digger does with his tin
dish, with this difference, that his ancient prototype allowed the water
and lighter particles to escape over the rim as he swirled the stuff
round and round. I presume, in finishing the operation, he collected the
golden grains by gently lapping the water over the reduced material,
much as we do now.

I have already spoken of the mode in which auriferous lode-stuff was
treated in early times--_i.e._, by grinding between stones. This is also
practised in Africa to-day, and we have seen that the Koreans, with
Mongolian acuteness, have gone a step farther, and pulverise the quartz
by rocking one stone on another. In South America the arrastra is still
used, which is simply the application of horse or mule power to the
stone-grinding process, with use of mercury.

The principal sources of the gold supply of the modern world have been,
first, South America, Transylvania in Europe, Siberia in Asia,
California in North America, and Australia. Africa has always produced
gold from time immemorial.

The later development in the Johannesburg district, Transvaal, which has
absorbed so many millions of English capital, is now, after much
difficulty and disappointment--thanks to British pluck and
skill--producing splendidly. The yield for 1898 was 4,295,609, and for
1903 2,859,477 ounces--a yield never before equalled by lode-mining from
one field.

In the year 1847 gold was discovered in California, at Sutor’s sawmill,
Sacramento Valley, where, on the water being cut off, yellow specks and
small nuggets were found in the tail race. The enormous “rush” which
followed is a matter of history and the subject of many romances, though
the truth has, in this instance, been stranger than fiction.

The yield of the precious metal in California since that date up to 1888
amounts to £256,000,000.

Following close on the American discovery came that of Australia, the
credit of which has usually been accorded to Hargraves, a returned
Californian digger, who washed out payable gold at Lewis Ponds Creek,
near Bathurst, in 1851. But there is now no reason to doubt that gold
had previously been discovered in several parts of that great island
continent. It may be news to many that the first gold mine worked in
Australia was opened about twelve miles from Adelaide city, S.A., in the
year 1848. This mine was called the Victoria; several of the Company’s
scrip are preserved in the Public Library; but some two years previous
to this a man named Edward Proven had found gold in the same
neighbourhood.

Most Governments nowadays encourage in every possible way the discovery
of gold-fields, and rewards ranging from hundreds to thousands of pounds
are given to successful prospectors of new auriferous districts. The
reward the New South Wales authorities meted out to a wretched convict,
who early in this century had dared to find gold, was a hundred lashes
vigorously laid on to his already excoriated back. The man then very
naturally admitted that the alleged discovery was a fraud, and that the
nugget produced was a melted down brass candlestick. One might have
imagined that even in those unenlightened days it would not have been
difficult to find a scientist sufficiently well informed to put a little
nitric acid on the supposed nugget, and so determine whether it was the
genuine article, without skinning a live man first to ascertain. My
belief is that the unfortunate fellow really found gold, but, as Mr.
Deas Thompson, the then Colonial Secretary, afterwards told Hargraves in
discouraging his reported discovery, “You must remember that as soon as
Australia becomes known as a gold-producing country it is utterly
spoiled as a receptacle for convicts.”

This, then, was the secret of the unwillingness of the authorities to
encourage the search for gold, and it is after all due to the fact that
the search was ultimately successful beyond all precedent, that
Australia has been for so many years relieved of the curse of
convictism, and has ceased once and for all to be a depôt for the
scoundrelism of Britain--“Hurrah for the bright red gold!”

From the year 1851 to 1897 the value of the gold raised in the
Australasian colonies realised the enormous amount of nearly
£550,000,000. One cannot help wondering where it all goes.

Mulhall gives the existing money of the world at 2437 million pounds, of
which 846 millions are paper, 801 millions silver, and 790 millions
gold. From 1830 to 1880 the world consumed by melting down plate, &c.,
4230 tons of silver more than it mined. From 1800 to 1870 the value of
gold was about 15½ times that of silver. From 1870 to 1880 it was
16·7 times the value of silver and now exceeds it over twenty times. In
1700 the world had 301 million pounds of money, and in 1860, 1180
million pounds sterling. In 1894 the current gold was worth about
£800,000,000.

The gold first worked for in Australia, as in other places, was of
course alluvial, by which is usually understood loose gold in nuggets,
specks, and dust, lying in drifts which were once the beds of long
extinct streams and rivers, or possibly the moraines of glaciers, as in
New Zealand.

Further on the differences will be mentioned between “alluvial” and
“reef” or lode gold, for that there is a difference in origin in many
occurrences, is, I think, provable. I hold, and hold strongly, that true
alluvial gold is not always derived from the disintegration of lodes or
reefs. For instance, the “Welcome Nugget” certainly never came from a
reef. No such mass of gold, or anything approaching it, has ever yet
been taken from a quartz matrix. It was found at Bakery Hill, Ballarat,
in 1858, weight 2195 ozs., and sold for £10,500. This was above its
actual value.

The “Welcome Stranger,” a still larger mass of gold, was found amongst
the roots of a tree at Dunolly, Victoria, in 1869, by two starved out
“fossickers” named Deeson and Oates. The weight of this, the largest
authenticated nugget ever found, was 2268½ ozs., and it was sold for
£10,000, but it was rendered useless as a specimen by the finders, who
spent a night burning it to remove the adhering quartz.

But the ordinary digger neither hopes nor expects to unearth such
treasures as these. He is content to gather together by means of
puddling machine, cradle, long tom, or even puddling tub and tin dish,
the scales, specks, dust, and occasional small nuggets ordinarily met
with in alluvial “washes.”

Having sunk to the “wash,” or “drift,” the digger, by means of one or
more of the appliances mentioned above, proceeds to separate the gold
from the clay and gravel in which it is found. Of course in large
alluvial claims, where capital is employed, such appliances are
superseded by steam puddlers, buddles, and other machinery, and
sometimes mercury is used to amalgamate the gold when very fine.
Hydraulicing is the cheapest form of alluvial mining, but can only be
profitably carried out where extensive drifts, which can be worked as
quarry faces, and unlimited water exist in the same neighbourhood. When
such conditions obtain a few grains of gold to the yard or ton will pay
handsomely.

    [Illustration: FIG. 2. LODE FORMATION IN SLATE AND SANDSTONE.]

Lode, or reef mining, is a more expensive and complicated process,
requiring much skill and capital. First, let me explain what a lode
really is. The American term is “ledge,” and it is not inappropriate or
inexpressive. Imagine then a ledge, or kerbstone, continuing to unknown
depths in the earth at any angle varying from perpendicular to nearly
horizontal. This kerbstone is totally distinct from the rocks which
enclose it; those on one side may be slate, on the other, sandstone
(Fig. 2); but the lode, separated usually by a small band of soft
material known to miners as “casing,” or “fluccan,” preserves always an
independent existence, and in many instances is practically bottomless
so far as human exploration is concerned.

There are, however, reefs or lodes which are not persistent in depth.
Sometimes the lode formation is found only in the upper and newer
strata, and cuts out when, say, the basic rocks (such as granite, &c.)
are reached. Again, there is a form of lode known among miners as a
“gash” vein (Fig. 3). It is sometimes met with in the older crystalline
slates, particularly when the lode runs conformably with the cleavage of
the rock.

    [Illustration: FIG. 3. GASH VEIN.]

Much ignorance is displayed on the subject of lode formation and the
deposition of metals therein, even by mining men of long experience.
Many still insist that lodes, particularly those containing gold, are of
igneous origin, and point to the black and brown ferro-manganic outcrops
in confirmation. It must be admitted that often the upper portions of a
lode present a strong appearance of fire agency, but exactly the same
appearance can be caused by oxidation of iron and manganese in water.

It may now be accepted as a proven fact that no true lode has been
formed, or its metals deposited except by aqueous action. That is to
say, the bulk of the lode and all its metalliferous contents were once
held in solution in subterranean waters, which were ejected by geysers
or simply filtered into fissures formed either by the shrinkage of the
earth’s crust in process of cooling or by volcanic force.

It is not contended that the effect of the internal fires had no
influence on the formation of metalliferous veins, indeed, it is certain
that they had, but the action was what is termed hydro-thermal (hot
water); and such action we may see in progress to-day in New Zealand,
where hot springs stream or spout above the surface, when the silica and
lime impregnated water, reduced in heat and released from pressure,
begins forthwith to deposit the minerals previously held in solution.
Hence the formation of the wondrous White and Pink Terraces, destroyed
by volcanic action some sixteen years since, which grew almost while you
watched. So rapidly was the silica deposited that a dead beetle or
ti-tree twig left in the translucent blue water for a few days became
completely coated and petrified.

Gold differs in its mode of occurrence from other metals in many
respects; but there is no doubt that it was once held in aqueous
solution and deposited in its metallic form by electro-chemical action.
It is true we do not find oxides, carbonates, or bromides of gold in
Nature, nor can we feel quite sure that gold now exists naturally as a
sulphide, chloride, or silicate, though the presumption is strongly that
it does. If so, the deposition of the gold may be ceaselessly
progressing.

Generally reef gold is finer as to size of the particles, and, as a
rule, inferior in quality to alluvial. Thus, in addition to the extra
labour entailed in breaking into one of the hardest of rocks, quartz,
the _madre de oro_ (“mother of gold”) of the Spaniards, there is the
additional labour required to pulverise the rock so as to set free the
tiniest particles of the noble metal it so jealously guards. There is
also the additional difficult operation of saving and gathering together
these small specks, and so producing the massive cakes and bars of gold
in their marketable state.

Having found payable gold in quartz on the surface, the would-be miner
has next to ascertain two things. First, the strike or course of the
lode; and secondly, its underlie, or dip. The strike, or course, is the
direction of the lode lengthwise.

In Australia the term “underlie” is used to designate the angle from the
perpendicular at which the lode lies in its enclosing rocks, and by
“dip” the angle at which it dips or inclines lengthwise on its course.
Thus, at one point the cap of a lode may appear on the surface, and some
distance further the cap may be hundreds of feet below. Usually a shaft
is sunk in the “reef” to prove the underlie, and a level, or levels,
driven on the course to ascertain its direction underground, also if the
gold extends, and if so, how far. This being proved, next a vertical
shaft is sunk on the hanging or upper wall side, and the reef is either
tapped thereby, or a cross-cut driven to intersect it.

We will now assume that our miners have found their lode payable, and
have some hundreds of tons of good gold-bearing stone in sight or at the
surface. They must next provide a reducing plant.

Of means for crushing or triturating quartz there is no lack, and every
year gives us fresh inventions for the purpose, each one better than
that which preceded it, according to its inventor. Most practical men,
however, prefer to continue the use of the stamper battery, which is
virtually a pestle and mortar on a large scale. Why we adhere to this
form of pulverising machine is that, though somewhat wasteful of power,
it is easily understood, its wearing parts are cheaply and expeditiously
replaced, and it is so strong that even the most perversely stupid
workman cannot easily break it or put it out of order.

The stone, being pounded into sand of such degree of fineness as the
gold requires, passes through a perforated iron plate called a
“grating,” or “screen,” on to an inclined surface of copper plates faced
with mercury, having small troughs, or “riffles,” containing mercury,
placed at certain distances apart.

The crushed quartz is carried over these copper “tables,” as they are
termed, thence over the blanket tables--that is, inclined planes covered
with coarse serge, blankets, or other flocculent material--so that the
heavy particles may be caught in the hairs, or is passed over vanners or
concentrating machines. The resulting “concentrates,” consisting for
the most part of sulphides of iron, copper, and lead, are washed off
from time to time and reserved for secondary treatment.

First, they are roasted to get rid of the sulphur, arsenic, &c, which
would interfere with the amalgamation or lixiviation, and then either
ground to impalpable fineness in one of the many triturating pans with
mercury, or treated by chlorine or cyanogen.

If, however, we are merely amalgamating, then at stated periods the
battery and pans are cleared out, the amalgam rubbed or scraped from the
copper plates and raised from the troughs and riffles. It is then
squeezed through chamois leather, or good calico will do as well, and
retorted in a large iron retort, the nozzle of which is kept in water so
as to convert the mercurial vapour again to the metallic form. The
result is a spongy cake of gold, which is either sold as “retorted” gold
or smelted into bars.

The other and more scientific methods of extracting the precious metal
from its matrices, such as lixiviation or leaching, by means of solvents
(chlorine, cyanogen, hyposulphite of soda, &c), will be more fully
described further on.




    CHAPTER II

    GOLD PROSPECTING--ALLUVIAL AND GENERAL


It is purposed in this chapter to deal specially with the operation of
searching for valuable mineral by individuals or small working parties.

It is well known that much disappointment and loss accrue through lack
of knowledge by prospectors, who with all their enterprise and energy
are often very ignorant, not only of the probable locality, mode of
occurrence, and widely differing appearance of the various valuable
minerals, but also of the best means of locating and testing the ores
when found. It is for the information of such as these that this chapter
is mainly intended, not for scientists or miners of large experience.

All of us who have had much to do with mining know that the majority of
the best mineral finds have been made by the purest accident; often by
men who had no mining knowledge whatever; and that many valuable
discoveries have been delayed, or, when made, abandoned as not payable,
from the same cause--ignorance of the rudiments of mineralogy and
mining. I have frequently been asked by prospectors, when inspecting new
mineral fields, what rudimentary knowledge will be most useful to them
and how it can be best obtained.

If a man can spare the time a course of lessons at some accredited
school of mines will be, undoubtedly, the best possible training; but if
he asks what books he should read in order to obtain some primary
technical instruction, I reply: First, an introductory text-book of
geology, which will tell him in the simplest and plainest language all
he absolutely requires to know on this important subject. Every
prospector should understand elementary geology so far as general
knowledge of the history of the structure of the earth’s crust and of
the several actions that have taken place in the past, or are now in
operation, modifying its conditions. He may with advantage go a few
steps further and learn to classify the various formations into systems,
groups, and series: but he can acquire all that he need absolutely know
from this useful little 2_s._ 6_d._ book. Next, it is advisable to learn
something about the occurrence and appearance of the valuable minerals
and the formations in which they are found. For all practical purposes I
can recommend Cox and Ratte’s “Mines and Minerals,” one of the Technical
Education series of New South Wales, which deals largely with the
subject from an Australian standpoint, and is therefore particularly
valuable to the Australian miner, but which will be found applicable to
most other gold-bearing countries. I must not, however, omit to mention
an admirably compiled _multum in parvo_ volume prepared by Mr. G.
Goyder, jun., Government Assayer and Assay Instructor at the School of
Mines, Adelaide. It is called the “Prospectors’ Pocketbook,” costs only
one shilling, is well bound, and of handy size to carry. In brief, plain
language it describes how a man, having learned a little of assaying,
may cheaply provide himself with a portable assay plant, and fluxes, and
also gives considerable general information on the subject of minerals,
their occurrence and treatment.[1]

    [1] Another excellent and really practical book is Prof. Cole’s
        “Practical Aids in Geology” (second edition), 10_s._ 6_d._

It may here be stated that twenty-one years ago the author did a large
amount of practical silver assaying on the Barrier Hill, which was not
then so accessible a place as it is now, and got closely correct results
from a number of different mines, with an extemporised plant almost
amusing in its simplicity. All I took from Adelaide were a small set of
scales capable of determining the weight of a button down to 20 ozs. to
the ton, a piece of cheese cloth to make a screen or sieve, a tin ring
1½ in. diameter, by 1/2 in. high, a small brass door knob to use as a
cupel mould, and some powdered borax, carbonate of soda, and argol for
fluxes; while for reducing lead I had recourse to the lining of a
tea-chest, which lead contains no silver--John Chinaman takes good care
of that. My mortar was a jam tin, without top or bottom, placed on an
anvil; the pestle a short steel drill. The blacksmith at Mundi Mundi
Station made me a small wrought iron crucible, also a pair of bent tongs
from a piece of fencing-wire. The manager gave me a small common red
flower pot for a muffle, and with the smith’s forge (the fire built
round with a few blocks of talcose schist) for a furnace, my plant was
complete. I burned and crushed bones to make my bone-dust for cupelling,
and thus provided made nearly forty assays, some of which were
afterwards checked in Adelaide, in each instance coming as close as
check assays generally do. Nowadays one can purchase cheaply a very
effective portable plant, or after a few lessons a man may by practice
make himself so proficient with the blowpipe as to obtain assay results
sufficiently accurate for most practical purposes.

Coming then to the actual work of prospecting. What the prospector
requires to know is, first, the usual locality of occurrence of the more
valuable minerals; secondly, their appearance; thirdly, a simple mode of
testing. With respect to occurrence, the older sandy and clay slates,
chlorite slates, micaceous, and hornblendic schists, particularly at or
near their junction with the intrusive granite and diorite, generally
form the most likely geological country for payable mineral lodes,
particularly gold, silver and tin. But those who have been engaged in
practical mining for long, finding by experience that no two mineral
fields are exactly alike in all their characteristics, have come to the
conclusion that it is unwise to form theories as to why metals should or
should not be found in certain enclosing rocks or matrices. Some of the
best reef gold got in Victoria has been obtained in dead white,
milky-looking quartz almost destitute of base metal. In South Australia
reef gold is almost invariably associated with iron, either an oxide, as
“gossan;” or ferruginous calcite, “limonite;” or granular silica,
conglomerated by iron, the “ironstone” which forms the capping or
outcrop of many of our reefs, and which is often rich in gold.

But to show that it is unsafe to decide off-hand in what class of
matrix metals will or will not be found, I may say that in my own
experience I have seen payable gold in the following materials:--

Quartz, dense and milky, also in quartz of nearly every colour and
appearance, saccharoidal, crystalline, nay, even in clear glass-like
six-sided prismatic crystals, and associated with silver, copper, lead,
arsenic, iron as sulphide, oxide, carbonate, and tungstate, antimony,
bismuth, nickel, zinc, lead, and other metals in one form or another; in
slate, quartzite, mica schist, granite, diorite, porphyry, felsite,
calcite, dolomite, common carbonate of iron, siliceous sinter from a hot
spring, as at Mount Morgan; as alluvial gold in drifts formed of almost
all these materials; and once, perhaps the most curious matrix of all, a
small piece of apparently alluvial gold, naturally imbedded in a shaly
piece of coal. This specimen, I think, is in the Sydney Museum. One
thing, however, the prospector may make sure of: he will always find
gold more or less intimately associated with silica (quartz) in one or
other of its many forms, just as he will always find cassiterite (oxide
of tin) in the neighbourhood of granite containing muscovite (white
mica), which so many people will persist in terming talc. It is stated
to be a fact that tin has never been found more than about two miles
from such granite.

From what has been said of its widely divergent occurrence, it will be
admitted that the Cornish miners’ saying with regard to metals generally
applies with great force to gold: “Where it is, there it is”: and
“Cousin Jack” adds, with pathetic emphasis, “and where it is generally,
there I ain’t.”

I have already spoken of the geological “country rock” in which reef
gold is most likely to be discovered--_i.e._, the junction of the slates
and schists with the igneous or metamorphic (altered) rocks, or in this
vicinity. Old river beds formed of gravelly drifts in the same
neighbourhood may probably contain alluvial gold, or shallow deposit of
“wash,” or hillsides and valleys will often carry good surface gold.
This is sometimes due to the denudation, or wearing away, of the hills
containing quartz veins--that is, where the alluvial gold really was
derived from such veins, which, popular opinion to the contrary, is not
always the case.

Much disappointment and loss of time and money would often be prevented
if prospectors would realise that _all_ alluvial gold does not come from
the quartz veins or reefs; and that following up an alluvial lead, no
matter how rich, will not inevitably develop a payable gold lode.
Sometimes gold, evidently of reef origin, is found in the alluvial; but
in that case it is generally fine as regards the size of the particles,
more or less sharp-edged, or crystalline in form if recently shed; while
such gold is often of poorer quality than the true alluvial which occurs
in mammillary (breast-like) nuggets, and is of a higher degree of purity
as gold.

The ordinary non-scientific digger will do well to give credence to this
view of the case, and will often thereby save himself much useless
trouble. Sometimes also the alluvial gold, coarser in size than true
reef-born alluvial, is derived almost _in situ_ from small quartz
“leaders,” or veins, which the grinding down of the face of the slates
has exposed; these leaders in time being also broken and worn, set free
the gold they have contained, which does not, as a rule, travel far, but
sometimes becomes waterworn by the rubbing over it of the disintegrated
fragments of rock.

But the heavy, true alluvial gold, in great pure masses, mammillary, or
botryoidal (like a bunch of grapes) in shape, have assuredly been formed
by accretion on some metallic base, from gold salts in solution,
probably chloride, possibly sulphide or silicate.

Nuggets, properly so-called, are never found in quartz lodes; but, as
will be shown later, a true nugget having all the characteristics of
so-called waterworn alluvial may be artificially formed on a small
piece of galena, or pyrites, by suspending the base metal in the loop of
a thread in a weak solution of chloride of gold in which a few hard-wood
chips are thrown.

Prospecting for alluvial gold at shallow depths is a comparatively easy
process, requiring no great amount of technical knowledge. Usually the
first gold is got at or near the surface and then traced to deep leads,
if such exist.

At Mount Brown Gold-field, N.S.W., in 1881, I saw claimholders turning
out to work equipped only with a small broom made of twigs and a tin
dish. With the broom they carefully swept out the crevices of the
decomposed slate as it was exposed on the surface, and putting the
resulting dust and fragments into the tin dish proceeded to dry blow it.

In “dry blowing” the operator takes the dish about half full of dirt,
and standing with his back or side to the wind, if there be any, begins
throwing the stuff up and catching it, or sometimes slowly pouring it
from one dish to another, the wind in either case carrying away the
finer particles. He then proceeds to reduce the quantity by carefully
extracting the larger fragments of rock, till eventually he has only a
handful or so of moderately fine “dirt” which contains any gold there
may be. If in good sized nuggets it is picked out, if in smaller pieces
or fine grains the digger slowly blows the sand and dust aside with his
breath, leaving the gold exposed. This process is both tedious and
unhealthy, and of course can only be carried out with very dry surface
dirt. The material in which the gold occurred at Mount Brown was
composed of broken slate and alluvium with a few angular fragments of
quartz. Yet, strange to say, the gold always had a waterworn appearance,
probably due to erosion by drifting sand as is so often the case in
Westralian so-called alluvial.

Dry blowing is now much in vogue on the West Australian fields owing to
the scarcity of water; but the great objection is first, the large
amount of dust the unfortunate dry blower has to carry about his person,
and secondly, that the peck of dirt which is supposed to last most men a
lifetime has to be made a continuous meal of every day.

    [Illustration: FIG. 4. PUDDLING TUB.]

    [Illustration: PLATE I.--TUB PUDDLING _To face p._ 18]

For wet alluvial prospecting the appliances, besides pick and shovel,
are puddling tub (Fig. 4 and Pl. I.), tin dish, and cradle (Fig. 5 and
Pl. II.); the latter, a man handy with tools can easily make for
himself.

    [Illustration: FIG. 5. SECTIONAL SKETCH OF CRADLE.]

In sinking, the digger should be careful (1) to avoid making his shaft
inconveniently small, and (2) not to waste his energy by sinking a huge
“new chum” hole, which usually starts by being about three times too
large for the requirements at the surface, but narrows in like a funnel
at 10 feet or less. A shaft, say 4 feet by 2 feet 6 inches and sunk
plumb, the ends being half rounded, is large enough for all requirements
to a considerable depth, though I have seen smart men, when they were in
a hurry to reach the drift, get down in a shaft even less in size.

The novice who is trying to follow or to find a deep lead must fully
understand that the present bed of the surface river may not, in fact
seldom does, indicate the ancient watercourses long since buried either
by volcanic or diluvial action, which contain the rich auriferous
deposits for which he is seeking; and much judgment and considerable
underground exploration are often required to decide on the true course
of leads. Only by a careful consideration of all the geological
surroundings can an approximate idea be obtained from surface inspection
alone; and the whole probable conditions which led to the present
contour of the country must be carefully taken into account.

How am I to know true bottom when I see it? asks the inexperienced
digger. Well, nothing but long experience and intelligent observation
will prevent mistakes at times, particularly in deep ground; but as a
general rule, though it may sound paradoxical, you may know the bottom
by the top.

That is, we will assume you are sinking in, say, 10 to 12 feet ground in
a gully on the bank of which the country rock is exposed, and is, say,
for instance, a clay slate or sandy slate set at a certain angle; then,
in all probability--unless there be a distinct fault or change in the
country rock between the slate outcrop and your shaft--the bottom will
be a similar slate, standing at the same angle; and this will very
probably be overlaid by a deposit of pipeclay, formed by the
decomposition of the slates.

From the crevices of these slates, sometimes penetrating to a
considerable distance, you may get gold, but it is a useless attempt to
sink through them. If the outcropping strata be a soft calcareous
(limey) sandstone or soft felspathic rock, and that be also the true
“bottom,” great care should be exercised, or one is apt to sink through
the bed rock, which may be very loose and decomposed. I have known
mistakes made in this way when many feet have been sunk, and driven
through what was actually bed rock, though so soft as to deceive even
men of experience. The formation, however, must be the guide, and except
in some specially difficult cases, a man can soon tell when he is really
on bed rock or “bottom.”

On an alluvial lead the object of every one is to “get on the gutter,”
that is, to reach the lowest part of the old underground watercourse,
through which for centuries the gold may have been accretionising from
the percolation of the mineral-impregnated water; or, when derived from
reefs or broken down leaders, the flow of water has acted as a natural
sluice wherein the gold is therefore most thickly collected. Sometimes
the lead runs for miles and is of considerable width, at others it is
irregular, and the gold-bearing “gutter” small and hard to find. In many
instances, for reasons not readily apparent, the best gold is not found
exactly at the lowest portion of these narrow gutters, but a little way
up the sides. This fact should be taken into consideration in
prospecting new ground, for many times a claim has been deserted after
cleaning up the “bottom,” and another man has got far better gold
considerably higher up on the sides of the gutter. For shallow alluvial
deposits, where a man quickly works out his 30 by 30 feet claim, it may
be cheaper at times to “paddock” the whole ground--that is, take all
away from surface to bottom, but if he is in wet ground and he has to
drive, great care should be taken to properly secure the roof by means
of timber. How this may best be done the local circumstances only can
decide. In loose or treacherous ground careful attention should be given
to timbering, _i.e._, securing the ground to prevent caving in.

    [Illustration: PLATE II.--CRADLING]




    CHAPTER III

    LODE OR REEF PROSPECTING


The preceding chapter dealt more especially with prospecting as
conducted on alluvial fields. I shall now treat of preliminary mining on
lodes or “reefs.”

As has already been stated, the likeliest localities for the occurrence
of metalliferous deposits are at or near the junction of the older
sedimentary formations with the igneous or intrusive rocks, such as
granites, diorites, &c. In searching for payable lodes, whether of gold,
silver, copper, or even tin in some forms of occurrence, the indications
are often very similar. The first prospecting is usually done on the
hilltops or ridges, because, owing to denudation by ice or water which
have bared the bedrock, the outcrops are there more exposed, and thence
the lodes are followed down through the alluvial covered plains, partly
by their “strike” or “trend,” and sometimes by other indicating
evidences, which the practical miner has learned to know.

For instance, a lesson in tracing the lode in a grass covered country
was taught me many years ago by an old prospector who had struck good
gold in the reef at a point some distance to the east of what had been
considered the true course. I asked him why he had opened the ground at
that particular place. Said he, “Some folks don’t use their eyes. You
stand here and look towards that claim on the rise where the reef was
last struck. Now, don’t you see there is almost a track betwixt here and
there where the grass and herbage is more withered than on either side?
Why? Well, because the hard quartz lode is close to the surface all the
way, and there is no great depth of soil to hold the moisture and make
the grass grow.”

I have found this simple lesson in practical prospecting of use since.
But the strike or course of a quartz reef is more often indicated by
outcrops, either of the silica itself or ironstone “blows,” as the
miners call them, but the term is a misnomer, as it argues the easily
disproved igneous theory of veins of ejection, meaning thereby that the
quartz with its metalliferous contents was thrown out in a molten state
from the interior of the earth. This has in no case occurred, and the
theory is an impossible one. True lodes are veins of injection formed by
the infiltration of silicated waters carrying the metals also in
solution. This water filled the fissures caused either by the cooling of
the earth’s crust, or formed by sudden upheavals of the igneous rocks.

Sometimes in alluvial ground the trend of the reef will be revealed by a
track of quartz fragments, more or less thickly distributed on the
surface and through the superincumbent soil. Follow these, and at some
point, if the lode be continuous, a portion of its solid mass will
generally be found to protrude and can then again be prospected.

There is no rule as to the trend or strike of lodes, except that a
greater number are found taking a northerly and southerly course than
one which is easterly and westerly. At all events, such is the case in
Australia, but it cannot be said that either has the advantage in being
more productive. Some of the richest mines in Australasia have been in
lodes running easterly and westerly, while gold, tin, and copper, in
great quantity and of high percentage to the ton, have been got in such
mines as Mount Morgan, Mount Bischoff, and the Burra, which contain no
lodes properly so-called.

Mount Morgan is the richest and most productive gold mine in Australasia
and amongst the best in the world.

Its yield for 1895 was 128,699 oz. of gold, valued at £528,700.
Dividends paid in 1895, £300,000.

This mine was opened in 1886. Up to May 31, 1897, the total yield was
1,631,981 ozs. of gold, sold at £6,712,187, from which £4,400,000 have
been paid in dividends. (See _Mining Journal_, for Oct. 9, 1897).

Mount Morgan shareholders have, in other words, divided over 43½ tons
of standard gold.

The Burra Burra copper mine, about 100 miles from Adelaide, in a
direction a little to the east of north, was found in 1845 by a shepherd
named Pickett. It is singularly situated on bald hills standing 130 ft.
above the surrounding country. The ores obtained from this mine have
been chiefly red oxides, very rich blue and green carbonates, including
malachite, and also native copper. The discovery of this mine,
supporting, as it did at one time a large population, marked a new era
in the history of the colony. The capital invested in it was £12,320 in
£5 shares, and no subsequent call was ever made upon the shareholders.
The total amount paid in dividends was £800,000. After being worked by
the original owners for some years the mine was sold to a new company,
but during the last few years it has not been worked, owing in some
degree to the low price of copper and also to the fact that the deposit
originally operated upon apparently became exhausted. For many years the
average yield was from 10,000 to 13,000 tons of ore, averaging 22 to 23
per cent. of copper. It is stated that, during the twenty-nine and a
half years in which the mine was worked, the company expended £2,241,167
in general expenses. The output of ore during the same period amounted
to 234,648 tons, equal to 51,622 tons of copper. This, at the average
price of copper, amounted to a money value of £4,749,224. The mine
stopped working in 1877.

Mount Bischoff, Tasmania, has produced, since the formation of the
Company to December 1895, 47,263 tons of tin ore. It is still in full
work and likely to be for years to come.

Each of these immense metalliferous deposits was found outcropping on
the summit of a hill of comparatively low altitude. There are no true
walls nor can the ore be traced away from the hill in lode form. These
occurrences are generally held to be due to hydro-thermal or geyser
action.

Then again lodes are often very erratic in their course. Slides and
faults throw them far from their true line, and sometimes the lode is
represented by a number of lenticular (double-pointed in section)
masses of quartz of greater or less length, either continuing point to
point or overlapping, “splicing,” as the miners call it (Fig. 6). Such
formations are very common in West Australia. All this has to be
considered and taken into account when tracing the run of stone.

    [Illustration: FIG. 6. LENTICULAR VEIN.]

The tyro also must carefully remember that in rough country where the
lode strikes across hills and valleys, the line of the cap or outcrop
will apparently be very sinuous owing to the rises and depressions of
the surface. Many people even now do not understand that true lodes or
reefs are portions of rock or material differing from the surrounding
and enclosing strata, and continuing down to unknown depths at varying
angles. Therefore, if you have a north and south lode outcropping on a
hill and crossing an east and west valley, the said lode, underlying
east, when you have traced its outcrop to the lowest point in the
valley, between the two hills, will be found to be a greater or less
distance, according to the angle of its dip or underlie, to the east of
the outcrop on the hill where it was first seen. If it be followed up
the next hill it will come again to the west, the amount of apparent
deviation being regulated by the height of the hills and depth of the
valley.

A simple demonstration will make this plain. Take a piece of half-inch
pine board, 2 ft. long and 9 in. wide, and imagine this to be a lode;
now cut a half circle out of it from the upper edge with a fret saw and
lean the board say at an angle of 45° to the left, look along the top
edge, which you are to consider as the outcrop on the high ground, the
bottom of the cut being the outcrop in the valley, and it will be seen
that the lowest portion of the cut is some inches to the right; so it is
with the lode, and in rough country very nice judgment is required to
trace the true course.

For indications, never pass an ironstone “blow” without examination.
Remember the pregnant Cornish saying with regard to mining and the
current aphorism, “The iron hat covers the golden head.” “Cousin Jack,”
put it “Iron rides a good horse.” The ironstone outcrop may cover a
gold, silver, copper, or tin lode.

If you are searching for gold, the presence of the royal metal should be
apparent on trial with the pestle and mortar; if silver, either by sight
in one of its various forms or by assay, blowpipe or otherwise; copper
will reveal itself by its peculiar colour, green or blue carbonates, red
oxides, or metallic copper. It is an easy metal to prospect for, and its
percentage is not difficult to determine approximately. Tin is more
difficult to identify, as it varies so greatly in appearance.

Having found your lode and ascertained its course, you want next to
ascertain its value. As a rule (and one which it will be well to
remember) if you cannot find payable metal, particularly in gold “reef”
prospecting, at or near the surface, it is not worth while to sink,
unless, of course, you design to strike a shoot of metal which some one
has prospected before you. The idea is exploded that auriferous lodes
necessarily improve in value with depth. The fact is that the metal in
any lode is not, as a rule, equally continuous in any direction, but
occurs in shoots dipping at various angles in the length of the lode, in
bunches or sometimes in horizontal layers. Nothing but actual exploiting
with pick, powder, and brains, particularly brains, will determine this
point.

Where there are several parallel lodes and a rich chute has been found
in one and the length of the payable ore ascertained, the neighbouring
lodes should be carefully prospected opposite to the rich spot, as often
similar valuable deposits will thus be found. Having ascertained that
you have, say, a gold reef payable at surface and for a reasonable
distance along its course, you next want to ascertain its underlie or
dip, and how far the payable gold goes down.

As a general thing in many parts of Australia--though by no means an
inflexible rule--a reef running east of north and west of south will
underlie east; if west of north and east of south it will go down to the
westward and so round the points of the compass till you come to east
and west; when if the strike of the lodes in the neighbourhood has come
round from north-east to east and west the underlie will be to the
south; if the contrary was the case, to the north. It is surprising how
often this mode of occurrence will be found to obtain. But I cannot too
strongly caution the prospector not to trust to theory but to prove his
lode and his metal by following it down on the underlie. “Stick to your
gold” is an excellent motto. As a general thing it is only when the lode
has been proved by an underlie shaft to water level and explored by
driving on its course for a reasonable distance that one need begin to
think of vertical shafts and the scientific laying out of the mine.

A first prospecting shaft need not usually be more than 5 ft. by 3 ft.
or even 5 ft. by 2 ft. 6 in., particularly in dry country. One may often
see in hard country stupid fellows wasting time, labour, and explosives
in sinking huge excavations as much as 10 ft. by 8 ft. in solid rock,
sometimes following down 6 inches of quartz.

When your shaft is sunk a few feet, you should begin to log up the top
for at least 3 ft. or 4 ft., so as to get a tip for your “mullock” and
lode stuff. This is done by getting a number of logs, say 6 inches
diameter, lay one 7 ft. log on each side of your shaft, cut two notches
in it 6 ft. apart opposite the ends of the shaft, lay across it a 5 ft.
log similarly notched, so making a frame like a large Oxford picture
frame. Continue this by piling one set above another till the desired
height is attained, and on the top construct a rough platform and erect
your windlass (Fig. 7). If you have an iron handle and axle I need not
tell you how to set up a windlass, but where timber is scarce you may
put together the winding appliance described in the chapter headed
“Rules of Thumb.”

    [Illustration: FIG. 7. DOUBLE WINDLASS WITH LOGGED UP BRACE.]

If you have “struck it rich” you will have the pleasure of seeing your
primitive windlass grow to a “whip,” a “whim,” and eventually to a big
powerful engine, with its huge drum and Eiffel tower-like “poppet heads”
or “derrick,” with their great spindle pulley wheels revolving at dizzy
speed high in air.

“How shall I know if I have payable gold so as to save time and trouble
in sinking?” says the novice. Truly it is a most important part of the
prospector’s art, whether he be searching for alluvial or reef gold or
any other valuable metal.

I presume you know gold when you see it?

    [Illustration: PLATE III.--WHIN. _To face p. 28._]

If you don’t, and the doubtful particle is coarse enough, take a needle
and stick the point into the questionable specimen. If gold the steel
point will readily prick it; if pyrites or yellow mica the point will
glance off or only scratch it.

The great importance of the first prospect from the reef is well shown
by the breathless intensity with which the two bearded, bronzed pioneer
prospectors in some trackless Australian wild bend over the pan in which
the senior “mate” is slowly reducing the sample of powdered lode stuff.
How eagerly they examine the last pinch of “black sand” in the corner of
the dish. Prosperity and easy times, or poverty and more “hard graft”
shall shortly be revealed in the last dexterous turn of the pan. Let us
hope it is a “pay prospect.”

The learner, if he be far afield and without appliances of any kind, can
only guess his prospect. An old prospector will judge from six ounces of
lode stuff within a few pennyweights of what will be the yield of a ton.
I have seen many a good prospect broken with the head of a pick and
panned in a shovel, but for reef prospecting you should have a pestle
and mortar. The handiest for travelling is a mortar made from a mercury
bottle cut in half, and a not too heavy wrought iron pestle with a
hardened face. To be particular you require a screen in order to get
your stuff to regulated fineness. The best for the prospector, who is
often on the move, is made from a piece of cheesecloth stretched over a
small hoop.

If you would be more particular take a small spring balance or an
improvised scale, such as is described in Mr. Goyder’s excellent little
book, p. 14, which will enable you to weigh down to one-thousandth of a
grain. It is often desirable to burn your stone before crushing, as it
is thus more easily triturated and will reveal all its gold; but
remember, that if it originally contained much pyrites, unless a similar
course is adopted when treated in the battery, some of the gold will be
lost in the pyrites.

Having crushed your gangue to a fine powder you proceed to pan it off in
a similar manner to that of washing out alluvial earth, except that in
prospecting quartz one has to be much more particular, as the gold is
usually finer. The pan is taken in both hands, and enough water to
cover the prospect by a few inches is admitted. The whole is then
swirled round, and the dirty water poured off from time to time till the
residue is clean quartz sand and heavy metal. Then the pan is gently
tipped, and a side to side motion is given to it, thus causing the
heavier contents to settle down in the “corner” or angle. Next the water
is carefully lapped in over the side, the pan being now tilted at a
greater angle until the lighter particles are all washed away. Nearly
all the water is got rid of, and the pan is then once more righted, and
the small amount of remaining water is passed over the pinch of heavy
mineral a few times, when the gold will be revealed in a streak along
the bottom. In this operation, as in all others, only practice will make
perfect, and a few practical lessons are worth whole pages of written
instruction.

To make an amalgamating assay that will prove the amount of gold which
can be got from a ton of your lode, take a number of samples from
different parts, both length and breadth. The drillings from the
blasting bore-holes collected make the best test. When finely triturated
weigh off one or two pounds, place in a black iron pan (it must not be
tinned), with 4 ozs. of mercury, 4 ozs. salt, 4 ozs. soda, and about
half a gallon of boiling water; then, with a stick, stir the pulp
constantly, occasionally swirling the dish as in panning off, till you
feel certain that every particle of the gangue has come in contact with
the mercury; then carefully pan off into another dish so as to lose no
mercury. Having got your amalgam clean squeeze it through a piece of
chamois leather, though a good quality of new calico previously wetted
will do as well. The resulting pill of hard amalgam can then be wrapped
in a piece of brown paper, placed on an old shovel, and the mercury
driven off over a hot fire; or a clay tobacco pipe, the mouth being
stopped with clay, makes a good retort (see “Rules of Thumb,” pipe and
potato retorting). The residue will be retorted gold, which, on being
weighed and the result multiplied by 2240 for a 1 lb. assay, or by 1120
for 2 lb., will give the amount of gold per ton which an ordinary
battery might be expected to save. Thus 1 grain to the pound, 2240 lbs.
to the ton, would show that the stuff contained 4 oz. 13 dwt. 8 gr. per
ton.

If there should be much base metal in your sample such as say stibnite
(sulphide of antimony), a most troublesome combination to the
amalgamator--instead of the formula mentioned above add to your mercury
about one dwt. of zinc shavings or clippings, and to your water
sufficient sulphuric acid to bring it to about the strength of vinegar
(weaker, if anything, not stronger), place your material preferably in
an earthenware or enamelled basin if procurable, but iron will do, and
intimately mix by stirring and shaking till the mercury has taken up all
it can. Retort as before described. This device is my own invention.
Never use the same pan for mercury and for prospecting, as the mercury
hides the gold by coating it.

The only genuine test after all is the battery, and that, owing to
various causes, is often by no means satisfactory. First, there is a
strong, almost unconquerable temptation to select the stone, thus making
the testing of a few tons give an unduly high average; but more often
the trouble is the other way. The stuff is sent to be treated at some
inefficient battery with worn-out mortars, shaky foundations, and uneven
tables, sometimes with the plates not half amalgamated, or coated with
impurities, the whole concern superintended by a man who knows as little
about the treatment of auriferous quartz by the amalgamating or any
other process as a dingo does of the differential calculus. Result: 3
dwt. to the ton in the retort, 30 dwt. in the tailings, and a payable
claim declared a “duffer.”

When the lode is really rich, particularly if it be carrying coarse
gold, and owing to rough country, or distance, a good battery is not
available, excellent results in a small way may be obtained by the
somewhat laborious, but simple, process of “dollying.” A dolly is a one
man power single stamp battery, or rather an extra sized pestle and
mortar (see “Rules of Thumb,” p. 152).

Silver lodes and lodes which frequently carry more or less gold, are
often found beneath the dark ironstone “blows,” composed of
conglomerates held together by ferric and manganic oxides; or, where the
ore is galena, the surface indications will frequently be a whitish
limey track, sometimes extending for miles, and nodules or “slugs” of
that ore will generally be found on the surface from place to place.
Most silver ores are easily recognisable, and readily tested by means of
the blowpipe or simple fire assay. Sometimes the silver on being tested
is found to contain a considerable percentage of gold, as in the great
Comstock lode in Nevada. Ore from the big Broken Hill silver lode, New
South Wales, also contains an appreciable quantity of the more precious
metal. A natural alloy of gold, termed electrum, contains 20 per cent.
silver.

Tin, lode, and stream, or alluvial, occurs only as an oxide, termed
cassiterite, and yet you can well appreciate the compliment one Cornish
miner pays to another whose cleverness he wishes to commend, when he
says of him, “Aw, he do knaw tin,” when you look at a representative
collection of tin ores. In various shapes, from sharp-edged crystals to
mammillary-shaped nuggets of wood-tin; from masses of 30 lbs. weight to
a fine sand, like gunpowder, in colour black, brown, grey, yellow, red,
ruby, white, and sometimes a mingling of several colours, it does
require much judgment to know tin.

Stream tin is generally associated with alluvial gold. When such is the
case both the gold and the tin can be saved, for the yellow metal is
much heavier. As the tin ore is an oxide which is not susceptible to
amalgamation, the gold can be readily separated by means of mercury.

Lode tin sometimes occurs in similar quartz veins to those in which gold
is got, and is occasionally associated with gold. Tin is also found, as
at Euriowie, in <DW18>s, composed of quartz crystals and large scales of
white mica, traversing the older slates. A similar occurrence takes
place at Mount Shoobridge and at Bynoe Harbour, in the Northern
Territory of South Australia; indeed, one could not readily separate the
stone from these three places if it were mixed. As before stated tin
will never be found far from granite, and that granite must have white
mica as one of its constituents. It is seldom found in the darker
 rocks, or in limestone country, but it sometimes occurs in
gneiss, mica schist, and chlorite schist. Numerous other minerals may be
mistaken for tin, such as common tourmaline or schorl, garnet, wolfram
(a tungstate of iron with manganese), rutile or titanic acid, blackjack
or zinc blende, together with magnetic, titanic, and specular iron in
fine grains.

The readiest way of determining whether the ore is tin is by weight, and
by scratching or crushing, when, what is called the “streak” is
obtained. The colour of the tin streak is whitey-grey, which, when once
known, is not easily mistaken. The specific gravity is about 7·0.
Wolfram, which is most like it, is a little heavier, from 7·0 to 7·5,
but its streak is red, brown, or blackish-brown. Rutile is much lighter,
4·2, and the streak light-brown; tourmaline is only 3·2. Blackjack is
4·3, and its streak yellowish-white. I have seen several pounds’ weight
to the dish got in some of the New South Wales shallow sinking
tin-fields, and, as a rule, payable gold was also present. Twenty-three
years ago I told Western Australian people that the neighbourhood of the
Darling range would produce rich tin, which it has done lately; there is
promise of a great development of the tin industry here. The tin “wash”
in question is reported to yield payable gold.

Metals are easily distinguished from non-metals by their lustre,
toughness, fusibility, opaqueness, conductivity, and rusting. Most
metals can be bent, twisted, drawn, and hammered to a degree not
possible in non-metals.

Sodium, potassium, lithium, and in a somewhat less degree, calcium,
strontium, and barium, will rust almost immediately when exposed to
moist air, and their white rusts quickly dissolve in water. Another
group of metals, zinc, lead, magnesium, and antimony, have white rusts
which are not soluble in water. Their rusts form a thin, adherent
coating, which gives the surface of the metal a dull appearance without
altogether concealing it. At higher temperatures than ordinary, if the
metals are finely divided, the chemical energy of rusting is so great
that the metals burn with a vivid light and give off a dense white
smoke. The permanency of these rusts and their protective character are
utilised in white paints.

A third group of metals have  rusts, _e.g._, silver, copper, and
iron. A fourth group never rust, such as gold and platinum, which occur
as metals in the gangue, not as ore from which the metal is produced. In
the case of the other metals it is an advantage that they are found in
the rust or ore condition, as they can be manufactured much more easily
than native metal.




    CHAPTER IV

    THE GENESIOLOGY OF GOLD--AURIFEROUS LODES


Up to a comparatively recent time it was considered heretical for any
one to advance the theory that gold had been deposited where found by
any other agency than that of fire. As late as 1860 Mr. Henry Rosales
convinced himself, and apparently the Victorian Government also, that
quartz veins with their enclosed metal had been ejected from the
interior of the earth in a molten state. His essay, which is very
ingenious and cleverly written, obtained a prize which the Government
had offered, but probably Mr. Rosales himself would not adduce the same
arguments in support of the volcanic or igneous theory to-day. His
phraseology is very technical; so much so that the ordinary inquirer
will find it somewhat difficult to follow his reasoning or understand
his arguments, which have apparently been founded only on the occurrence
of gold in some of the earlier discovered quartz lodes, and the
conclusions at which he arrived are not borne out by later experience.
He says:--“While, however, there are no apparent signs of mechanical
disturbances, during the long period that elapsed from the cooling of
the earth’s surface to the deposition of the Silurian and Cambrian
systems, it is to be presumed that the internal igneous activity of the
earth’s crust was in full force, so that on the inner side of it, in
obedience to the laws of specific gravity, chemical attraction, and
centrifugal force, a great segregation of silica in a molten state took
place. This molten silica continually accumulating, spreading, and
pressing against the horizontal Cambro-Silurian beds during a long
period at length forced its way through the superincumbent strata in all
directions; and it is abundantly evident, under the conditions of this
force and the resistance offered to its action, that the line it would
and must choose would be along any continuous and slightly inclined
diagonal, at times crossing the strata of the schists, though generally
preferring to develop itself and egress between the cleavage planes and
dividing seams of the different schistose beds.”

He goes on to say, “Another argument to the same end (_i.e._, the
igneous origin) may be shown from the fact that the auriferous quartz
lodes have exercised a manifest metamorphic action on the adjacent walls
or casing; they have done so partly in a mineralogical sense, but
generally there has been a metamorphic alteration of the rock.” Mr.
Rosales then tells his readers, what we all know must be the case, that
the gold would be volatilised by the heat, as would be also the other
metals, which he says, were in the form of arseniurets and sulphurets;
but he fails to explain how the sublimated metals afterwards reassumed
their metallic form. Seeing that, in most cases, they would be
hermetically enclosed in molten and quickly solidifying silica they
could not be acted on to any great extent by aqueous agency. Neither
does Mr. Rosales’s theory account at all for auriferous lodes; which
below water level are composed of a solid mass of sulphide of iron with
traces of other sulphides, gold, calcspar, and a comparatively small
percentage of silica. Nor will it satisfactorily explain the auriferous
antimonial silica veins of the New England district, New South Wales, in
which quantities of angular and unaltered fragments of slate from the
enclosing rocks are found imbedded in the quartz.

With respect to the metamorphism of the enclosing rocks to a greater
degree of hardness, which Mr. Rosales considered was due to heat, it
should be remembered that these rocks in their original state were much
softer and more readily fusible than the quartz, consequently all would
have been molten and mingled together instead of showing as a rule
clearly defined walls. It is much more rational to suppose that the
increased hardness imparted to the slates and schists at or near their
contact with the lode is due to an infiltration of silica from the
silicated solution which at one time filled the fissure. Few scientists
can now be found to advance the purely igneous theory of lode
formation, though it must be admitted that volcanic action has probably
had much influence not only in the formation of mineral veins, but also
on the occurrence of the minerals therein. But the action was
hydro-thermal, just such as was seen in course of operation in New
Zealand a few years ago when, in the Rotomahana district, one could
actually see the growing of the marvellous White and Pink Terraces
formed by the release of silica from the boiling water exuding from the
hot springs, which water, so soon as the heat and pressure were removed,
began to deposit its silica very rapidly; while at the Thames
Gold-field, in the same country hot, silicated water continuously boiled
out of the walls of some of the lodes after the quartz had been removed
and re-deposited a siliceous sinter thereon.

On this subject I note the recently published opinions of Professor
Lobley, a gentleman whose scientific reputation entitles his utterances
to respect, but who, when he contends that gold is not found in the
products of volcanic action is, I venture to think, arguing from
insufficient premisses. Certainly his theories do not hold good either
in Australasia or America where gold is often, nay, more usually, found
at, or near, either present or past regions of volcanic action.

It is always gratifying to have one’s theories confirmed by men whose
opinions carry weight in the scientific world. About twenty-four years
ago I first published certain theories on gold deposition, which, even
then, were held by many practical men, and some scientists, to be open
to question. Of late years, however, the theory of gold occurrence by
deposition from mineral salts has been accepted by all but the “mining
experts” who infest and afflict the gold mining camps of the world.
These opine that gold ought to occur in “pockets” only (meaning thereby
their own).

Recently Professor Joseph Le Conte, at a meeting of the American
Institute of Mining Engineers, criticised a notable essay on the
“Genesis of Ore Deposits,” by Bergrath F. Posepny. The Professor’s
general conclusions are:

     1. “Ore deposits, using the term in its widest sense, may
     take place from any kinds of waters, but especially from alkaline
     solutions, for these are the natural solvents of metallic
     sulphides, and metallic sulphides are usually the original form of
     such deposits.”

     2. “They may take place from waters at any temperature and any
     pressure, but mainly from those at high temperature and under heavy
     pressure, because, on account of their great solvent power, such
     waters are heavily freighted with metals.”

     3. “The depositing waters may be moving in any direction, up
     coming, horizontally moving, or even sometimes down-going, but
     mainly up-coming; because by losing heat and pressure at every step
     such waters are sure to deposit abundantly.”

     4. “Deposits may take place in any kind of waterways--in open
     fissures, in incipient fissures, joints, cracks, and even in porous
     sandstone, but especially in great open fissures, because these are
     the main highways of ascending waters from the greatest depths.”

     5. “Deposits may be found in many regions and in many kinds
     of rocks, but mainly in mountain regions, and in metamorphic and
     igneous rocks, because the thermosphere is nearer the surface, and
     ready access thereto through great fissures is found mostly in
     these regions and in these rocks.”

These views are in accordance with nearly all modern research into this
interesting and fruitful subject.

Among the theories which they discredit is that ore bodies may usually
be assumed to become richer in depth. As applied to gold lodes the
teaching of experience does not bear out this view.

If it be taken into account that the time in which most of our
auriferous siliceous lodes were formed was probably that indicated in
Genesis as before the first day or period when “the earth was without
form and void, and darkness was upon the face of the deep,” it will be
realised that the action we behold now taking place in a small way in
volcanic regions, was probably then almost universal. The crust of the
earth had cooled sufficiently to permit water to lie on its surface,
probably in hot shallow seas, like the late Lake Rotomahana. Plutonic
action would be very general, and volcanic mud, ash, and sand would be
ejected and spread far and wide, which, sinking to the bottom of the
water, may possibly be the origin of what we now designate the azoic or
metamorphic slates and schists, as also the early Cambrian and Silurian
strata. These, from the superincumbent weight and internal heat, became
compacted, and, in some cases, crystallised, while at the same time,
from the ingress of the surface waters to the heated regions below,
probably millions of geysers were spouting their mineral impregnated
waters in all directions; and in places where the crust was thin,
explosions of super-heated steam caused huge upheavals, rifts, and
chasms, into which these waters returned, to be again ejected, or to be
the cause of further explosions. Later, as the cooling-process
continued, there would be shrinkages of the earth’s crust causing other
fissures; intrusive granites further dislocated and upheaved the slates.
About this age, probably, when really dry land began to appear, came the
first formation of mineral lodes, and the waters, heavily charged with
silicates, carbonates of lime, sulphides, &c., in solution, commenced to
deposit their contents in solid form when the heat and pressure were
removed.

I am aware that part of the theory here propounded as to the probable
mode of formation of the immense sedimentary beds of the Archaic or
Azoic period is not altogether orthodox--_i.e._, that the origin of
these beds is largely due to the ejection of mud, sand, and ashes from
subterraneous sources, which, settling in shallow seas, were afterwards
altered to their present form. It is difficult, however, to believe that
at this very early period of geologic history so vast a time had elapsed
as would be required to account for these enormous depositions of
sediment, if they were the result only of the degradation of previously
elevated portions of the earth’s surface by water agency. Glacial action
at that time would be out of the question.

But what about the metals? Whence came the metallic gold of our reefs
and drifts? What was it originally--a metal or a metallic salt, and if
the latter, what was its nature?--chloride, sulphide, or silicate, one,
or all three? I incline to the latter hypothesis. All three are known,
and the chemical conditions of the period were favourable for their
natural production. Assuming that they did exist, the task of accounting
for the mode of occurrence of our auriferous quartz lodes is
comparatively simple. Chloride of gold is at the present day contained
in sea water and in some mineral waters, and would have been likely to
be more abundant during the Azoic and early Paleozoic period.

Sulphide of gold would have been produced by the action of sulphuretted
hydrogen; hence probably our auriferous pyrites lodes, while silicate of
gold might have resulted from a combination of gold chlorides with
silicic acid, and thus the frequent presence of gold in quartz be
accounted for.

A highly interesting and instructive experiment, showing how gold might
be, and probably was, deposited in quartz veins, was carried out by
Professor Bischof some years ago. He, having prepared a solution of
chloride of gold, added thereto a solution of silicate of potash,
whereupon, as he states, the yellow colour of the chloride disappeared,
and in half an hour the fluid turned blue, and a gelatinous dark-blue
precipitate appeared and adhered to the sides of the vessel. In a few
days moss-like forms were seen on the surface of the precipitate,
presumably approximating to what we know as dendroidal gold--that is,
having the appearance of moss, fern, or twigs. After allowing the
precipitate to remain undisturbed under water for a month or two a
decomposition took place, and in the auriferous silicate specks of
metallic gold appeared. From this the Professor argues, and with good
show of reason, that as we know now that the origin of our quartz lodes
was the silicates contained in certain rocks, it is probable that a
natural silicate of gold may be combined with these silicates. If this
can be demonstrated, the reason for the almost universal occurrence of
gold in quartz is made clear.

About 1870, Mr. Skey, analyst to the New Zealand Geological Survey
Department, made a number of experiments of importance in respect to the
occurrence of gold. These experiments were summarised by Sir James
Hector in an address to the Wellington Philosophical Society in 1872.
Mr. Skey’s experiments disproved the view generally held that gold is
unaffected by sulphur or sulphuretted hydrogen gas, and showed that
these elements combined with avidity, and that the gold thus treated
resisted amalgamation with mercury. Mr. Skey proved the act of
absorption of sulphur by gold to be a chemical act, and that electricity
was generated in sufficient quantity and intensity during the process
to decompose metallic solutions. Sulphur in certain forms had long been
known to exercise a prejudicial effect upon the amalgamation of gold,
but this had always been attributed to the combination of the sulphur
with the quicksilver used. Now, however, it is certain that the
sulphurising of the gold must be taken into account. We must remember
that the particles of gold in the stone may be enveloped with a film of
auriferous sulphide, by which they are protected from the solvent action
of the mercury. The sulphurisation of the gold gives no ocular
manifestation by change of colour or perceptible increase of weight, as
in the case of the formation of sulphides of silver, lead and other
metals, on account of the extremely superficial action of the sulphur,
and hence probably the existence of the gold sulphide escaped detection
by chemists.

Closely allied to this subject is the investigation of the mode in which
certain metals are reduced from their solutions by metallic sulphides,
or, in common language, the influence which the presence of such
substances as mundic and galena may exercise in effecting the deposit of
pure metals, such as gold, in mineral lodes. The close relation which
the richness of gold veins bears to the prevalence of pyrites has been
long familiar both to scientific observers and to practical miners. The
gold is an after deposit to the pyrites, and, as Mr. Skey was the first
to explain, due to its direct reducing influences. By a series of
experiments Mr. Skey proved that the reduction of the metal was due to
the direct action of the sulphide, and showed that each grain of iron
pyrites, when thoroughly oxidised, will reduce 12¼ grains of gold
from its solutions as chloride. He also included salts of platina and
silver in this general law, and demonstrated that solutions of any of
these metals traversing a vein rock containing certain sulphides would
be decomposed, and the pure metal deposited. We are thus enabled to
comprehend the constant association of gold, or native alloys of gold
and silver, in veins which traverse rocks containing an abundance of
pyrites, whether they have been formed as the result of either
sub-aqueous volcanic outbursts or by the metamorphism of the
deeper-seated strata which compose the superficial crust of the earth.

Mr. Skey also showed by very carefully conducted experiments that the
metallic sulphides are not only better conductors of electricity than
has hitherto been supposed, but that when paired they were capable of
exhibiting strong electro-motive power. Thus, if galena and zinc blende
in acid solutions be connected in the usual manner by a voltaic pair,
sulphuretted hydrogen is evolved from the surface of the former, and a
current generated which is sufficient to reduce gold, silver or copper
from their solutions in coherent electro-plate films. The attributing of
this property of generating voltaic currents, hitherto supposed to be
almost peculiar to metals, to the common sulphides found in
metalliferous veins, led Mr. Skey to speculate how far the currents
discovered to exist in such veins by Mr. E. F. Fox might be produced by
the gradual oxidation of mixed sulphides, and his conclusion is that
veins containing bands of different metallic sulphides, bounded by
continuing walls, and saturated with mineral waters, may constitute
under some circumstances a large voltaic battery competent to produce
electro-deposition of metals, and that the order of the deposit of these
mineral lodes will be found to bear a definite relation to the order in
which the sulphides rank in the table of their electro-motive power.
These researches may lead to some clearer comprehension of the law which
regulates the distribution of auriferous veins, and may explain why in
some cases the metal should be nearly pure, while in others it is so
largely alloyed with silver.

The following extract was lately clipped from a mining paper. If true,
the experiment is interesting:--

    “An American scientist has just concluded a very interesting
    and suggestive experiment. He took a crushed sample of rich ore
    from <DW36> Creek, which carried 1,100 ozs. of gold per ton, and
    digested it in a very weak solution of sodium chloride and sulphate
    of iron, making the solution correspond as near as practicable to
    the waters found in Nature. The ore was kept in a place having a
    temperature little less than boiling water for six weeks, when all
    the gold was dissolved, except what would be equal to one ounce
    per ton. A few small crystals of pyrite were then placed in the
    bottle of solution, and the gold began immediately to precipitate
    on them. It was noticeable, however, that the pyrite crystals which
    were free from zinc, galena, or other extraneous matter received no
    gold precipitate. Those which had such foreign associations were
    beautifully covered with fine gold crystals.”

Experimenting in a somewhat similar direction about eight years ago, I
found that the West Australian mine water, mentioned on page 85, with
the addition of an acid, was a solvent of gold. The idea of boiling it
did not occur to me, as the action was fairly rapid in cold water.

Assuming, then, that gold originally existed as a mineral salt, when and
how did it take metallic form? Doubtless, just in the same manner as we
now (by means of well-known reagents which are common in nature)
precipitate it in the laboratory. With regard to that found in quartz
lodes finely disseminated through the gangue, the change was brought
about by the same agency which caused the silicic acid to solidify and
take the form in which we now see it in the quartz veins. Silica is
soluble in solutions of alkaline carbonates, as shown in New Zealand
geysers; the solvent action being increased by heat and pressure, so
also would be the silicate or sulphide of gold. When, however, the
waters with their contents were released from internal pressure and
began to lose their heat the gold would be precipitated together with
the salts of some other metals, and would, where the waters could
percolate, begin to accretionise, thus forming the heavy or specimen
gold of some reefs. On this class of deposition I shall have more to say
when treating of the origin of alluvial gold in the form of nuggets.

Mr. G. F. Becker, of the United States Geological Survey, writing of the
geology of the Comstock lode, says:--“Baron Von Richthofen was of
opinion that fluorine and chlorine had played a large part in the ore
deposition in the Comstock, and this the writer is not disposed to deny;
but, on the other hand, it is plain that most of the phenomena are
sufficiently accounted for on the supposition that the agents have been
merely solutions of carbonic and hydrosulphuric acids. These reagents
will attack the bisilicates and felspars. The result would be carbonates
and sulphides of metals, earths, alkalies, and free quartz, but quartz
and sulphides of the metals are soluble in solutions of carbonates and
sulphides of the earths and alkalies, and the essential constituents of
the ore might, therefore, readily be conveyed to openings in the vein
where they would have been deposited on relief of pressure and
diminution of temperature. An advance boring on the 3000 ft. level of
the Yellow Jacket struck a powerful stream of water at 3065 ft. (in the
west country), which was heavily charged with hydrogen sulphide, and had
a temperature of 170° F., and there is equal evidence of the presence of
carbonic acid in the water of the lower levels. A spring on the 2700 ft.
level of the Yellow Jacket which showed a temperature of about 150° F.,
was found to be depositing a sinter largely composed of carbonates.”

It may be worth while here to speak of the probable reason why gold, and
indeed, almost all the metals generally occur in chutes in the lodes;
and why, as is often the case, these chutes are found to be more or less
in a line with each other in parallel lodes, and why also the junction
of two lodes is frequently specially productive. The theory with respect
to these phenomena which appears most feasible is, that at these points
certain chemical action has taken place, by which the deposition of the
metals has been specially induced. Generally a careful examination of
the enclosing rocks where the chute is found will reveal some points of
difference from the enclosing rocks at other parts of the course of the
lode, and when ore chutes are found parallel in reefs running on the
same course, bands or belts of similar country rock will be found at the
productive points. From this we may fairly reason that at these points
the slow stream filling the lode cavity met with a reagent percolating
from this particular band of rock, which caused the deposition of its
metals; and, indeed, I am strongly disposed to believe that the
deposition of metals, particularly in some loose lodes, may even now be
proceeding. But as in Nature’s laboratory the processes, if certain, are
slow, this theory may be difficult to prove.

Why the junction of lodes is often found to be more richly metalliferous
than neighbouring parts is probably because there the depositing
reagents met. This theory is well put by Mr. S. Herbert Cox, late of
Sydney, in his useful book, “Mines and Minerals.” He says:--“It is a
well-known fact in all mining districts that the junctions of lodes are
generally the richest points, always supposing that this junction takes
place in ‘kindly country,’ and the explanation of this we think is
simple on the aqueous theory of filling of lodes. The water which is
traversing two different channels of necessity passes through different
belts of country, and will thus have different minerals in solution. As
a case in point, let us suppose that the water in one lode contained in
solution carbonates of lime, and the alkalies and silica derived from a
decomposition of felspars; and that the other, charged with
hydrosulphuric acid, brought with it sulphide of gold dissolved in
sulphide of lime. The result of these two waters meeting would be that
carbonate of lime would be formed, hydrosulphuric acid would be set
free, and sulphide of gold would be deposited, as well as silica, which
was formerly held in solution by the carbonic acid.”

Most practical men who have given the subject attention will, I think,
be disposed to coincide with this view, though there are some who hold
that the occurrence of these parallel ore chutes and rich deposits at
the junctions of lodes is due to extraneous electrical agency. Of this,
however, I have failed to find any satisfactory evidence.

There is, however, proof that lodes are actually re-forming and the
action observed is very interesting as showing how the stratification in
some lodes has come about. The growth of silica on the sides of the
drives has occurred in some of the mines on the Thames gold-fields, New
Zealand (p. 36), where in some cases the deposition was so rapid as to
be noticeable from day to day, whilst the big pump, which drained all
the mines in the vicinity, was actually choked by siliceous deposits. In
old auriferous workings which have been under water for years, in many
parts of the world, formations of iron and silica have been found on the
walls and roof, while in mining tunnels which have been long unused
stalactites composed of silica and calcite have formed. Then, again,
experiments made by the late Professor Cosmo Newbery, in Victoria,
showed that a distinctly appreciable amount of gold, iron, and silica
(the latter in granular form) could be extracted from solid mine timber,
which had been submerged for a considerable time.

This reaction then must be in progress at the present time, and
doubtless under certain conditions pyrites would eventually take the
place of the timber, as is the case with some of the long buried
driftwood found in Victorian deep leads. Again, we know that the water
from some copper mines is so charged with copper sulphate that if scrap
iron be thrown into it, the iron will be taken up by the sulphuric acid,
and metallic copper deposited in its place. All this tends to prove that
the deposition of metals from their salts, though probably not now as
rapid as formerly, is still ceaselessly going on in some place or
another where the necessary conditions are favourable.

Quite unexpectedly I lately came across these lines in Dryden’s _Annus
Mirabilis_, verse cxxxix.:--

    “As those who unripe veins in mines explore,
        On the rich bed again the warm turf lay,
    Till time digests the yet imperfect ore,
        And know it will be gold another day.”

    _Is_ there “any new thing under the sun?”

With regard to auriferous pyritous lodes, it does not appear even now to
be clear, as some scientists assert, that their gold is never found in
chemical combination with the sulphides of the base metals. On the
contrary, I think much of the evidence points in the other direction.

I have long been of opinion that it is really so held in many of the
ferro-sulphides and arsenio-ferro sulphides. On this subject Mr. T.
Atherton contributed a short article in 1891 to the _Australian Mining
Standard_ which is worthy of notice. He says, referring to an occurrence
of a Natural Sulphide of Gold:--“The existence of gold, in the form of a
natural sulphide in conjunction with pyrites, has often been advanced
theoretically, as a possible occurrence; but up to the present time has,
I believe, never been established as an actual fact.” During my
investigations on the ore of the Deep Creek mines, Nambucca, New South
Wales, I found in them what I believe to be gold existing as a natural
sulphide. The lode is a large irregular one of pure arsenical pyrites
carrying, in addition to gold and silver, nickel and cobalt. It exists
in a felsite <DW18> immediately on the coast. Surrounding it on all sides
are micaceous schists, and in the neighbourhood about half a mile
distant is a large granite hill about 800 feet high. In the lode and its
walls are large quantities of pyrophyllite, and in some parts of the
mine there are deposits of pure white translucent mica, but in the ore
itself it is a yellow or pale olive green, and is never absent from the
pyrites.

From the first I was much struck with the exceedingly fine state of
division in which the gold existed in the ore. After roasting and very
carefully grinding down in an agate mortar, I have never been able to
get any pieces of gold exceeding one-thousandth of an inch in diameter,
and the greater quantity is very much finer than this. Careful
dissolving of the pyrites and gangue so as to leave the gold intact
failed to find it in any larger diameter. As this was a very unusual
experience in investigations on many other kinds of pyrites, I was led
further into the matter.

Ultimately, after a number of experiments, there was nothing left but to
test for gold existing as a natural sulphide. Taking 200 gr. of gold
from a sample assaying 17 oz. fine gold per ton, grinding it finely and
heating for some hours with yellow sodium sulphide--on decomposing the
filtrate and treating for gold I got a result at the rate of 12 oz. per
ton. This was repeated several times with the same result.

This sample came from the lode at the 140 ft. level, whilst samples from
the higher levels where the ore is more oxidised, although carrying the
gold in exactly the same degree of fineness, do not give as high a
percentage of auric sulphide.

It would appear that all the gold in the pyrites (and I have never found
any gold existing apart from the pyrites) has originally taken its place
there as a sulphide.

The following is an analysis of a general sample insoluble in
nitro-sulphuric acid:--

  20·532 per cent, consisting of {Silica       13·940 per cent.
                                 {Alumina       6·592     ”
                                  Lime          0·903     ”
                                  Sulphur      16·584     ”
                                  Arsenic      33·267     ”
                                  Iron         27·720     ”
                                  Cobalt        0·964     ”
                                  Nickel       Traces.
  (5 oz.  3 dwt. 8 gr. per ton)   Gold            --
  (0 oz. 16 dwt. 0 gr.   ”    )   Silver          --
                                                -------
                                  Total         99·970    ”

Professor Newbery, who made many valuable suggestions on the subject,
says, speaking of gold in pyritous lodes:--

    “As it (the gold salt) may have been in the same solution
    that deposited the pyrites, which probably contained its iron in
    the form of proto-carbonate with sulphates, it was not easy at
    first to imagine any ordinary salt of iron; but this I find can
    be accomplished with very dilute solutions in the presence of an
    alkaline carbonate and a large excess of carbonic acid, both of
    which are common constituents of mineral waters, especially in
    Victoria. This is true of chloride of gold, and if the sulphide is
    required in solution, it is only necessary to charge the solution
    with an excess of sulphuretted hydrogen. In this manner both
    sulphides may be retained in the same solution, depositing gradually
    with the escape of the carbonic acid.”

Pyritous lodes usually contain a considerable proportion of calcareous
matter, mostly carbonates, and consequently it appears not improbable
that the gold may remain in some instances as a sulphide, particularly
in samples of pyrites, in which it cannot be detected even by the
microscope until by calcination the iron sulphide is changed to an
oxide, wherein the gold may be seen in minute metallic specks. The whole
subject is full of interest, and careful scientific investigation may
lead to astonishing results.




    CHAPTER V

    THE GENESIOLOGY OF GOLD--AURIFEROUS DRIFTS


Having considered the origin of auriferous lodes, and the mode by which
in all probability the gold was conveyed to them and deposited as a
metal, it is necessary also to inquire into the derivation of the gold
of our auriferous drifts, and the reasons for its occurrence therein.

When quite a lad on the Victorian alluvial fields, I frequently heard
old diggers assert that gold grew in the drifts where found. At the time
we understood this to mean that it grew like potatoes; and, although not
prepared with a scientific argument to prove that such was not so, the
idea was generally laughed at. I have lived to learn that these old
hard-heads were nearer the truth than possibly they clearly realised,
and that gold does actually grow or agglomerate; and, indeed, is
probably even now thus growing, though it is likely that the chemical
and electric action in the mineral waters flowing through the drifts is
not in this age nearly so active as formerly.

Most boys have tried the experiment of dipping a clean-bladed knife into
sulphate of copper, and so depositing on the steel a film of copper,
which adheres closely until worn away. This is a simple demonstration of
a hydro-metallurgical process, though probably young hopeful is not
aware of the fact; and it is really by an enlargement of this process
that our beautiful and artistic gold-and silver-plated ware is
produced.

In the great laboratory of Nature similar chemical depositions have
taken place in the past, and may still be in progress; indeed, there is
sound scientific reason to suppose that in certain localities this is
even now the case, and that in this way much of our so-called alluvial
gold has been formed, that is, by the deposition on metallic bases of
the gold held in solution.

We will, however, take, to begin with, the generally accepted theory as
to the occurrence of alluvial gold. First, let it be said, that certain
alluvial gold is unquestionably derived from the denudation of quartz
lodes. Such is the gold dust found in many Asiatic and African rivers,
in the great placer mines of California, as also the gold dust gained
from the beach sand on the west coast of New Zealand, or in the enormous
alluvial drifts of the Shoalhaven Valley, New South Wales. Of the first,
many fabulous tales are told to account for its being found in
particular spots each summer after the winter floods, and miraculous
agency was asserted, while the early beachcombers of the Hokitika
district found an equally ridiculous derivation for their gold, which
was always more plentiful after heavy weather. They imagined that the
breakers were disintegrating some abnormally rich auriferous reefs out
at sea, and that the resultant gold was washed up on the beach.

The facts are simply, with regard to the rivers, that the winter floods
break down the drifts in the banks and agitate the auriferous detritus,
thus acting as natural sluices, and cause the metal to accumulate in
favourable spots; whilst on the New Zealand coast the heavy seas
breaking on the shingly beach, carry off the lighter particles, leaving
behind the gold, which is so much heavier. These beaches are composed,
as also are the “terraces” behind, of enormous glacial and fluvial
deposits, all containing more or less gold, and extend inland to the
foot of the mountains.

It is almost certain that the usually fine gold got by hydraulicing in
Californian cañons, in the gullies of the New Zealand Alps, and the
great New South Wales drifts, is largely the result of the attrition of
the boulders and gravel of moraines, which has thus freed, to a certain
extent, the auriferous particles. But when we find large nuggety masses
of high carat gold in the beds of dead rivers, another origin has to be
sought.

As previously stated, there is fair reason to assume that at least three
salts of gold have existed, and, possibly, may still be found, in
Nature--silicate, sulphide, and chloride. All of these are soluble and
in the presence of certain reagents, also existing naturally, can be
deposited in metallic form. Therefore, if, as is contended, reef gold
was formed with the reefs from solutions in mineral waters, by
inferential reasoning it can be shown that much of our alluvial gold was
similarly derived.

The commonly accepted theory, however, is that the alluvial gold of our
drifts has been ground out of the solid siliceous lodes by glacial and
fluvial action, and that the auriferous leads have been formed by the
natural sluicing operations of former streams. To this, however, there
are several insuperable objections.

First, how comes it that alluvial gold is usually superior in purity to
the “reef” gold immediately adjacent? Second, why are masses of gold,
such as the huge nuggets found in Victoria and New South Wales, never
been discovered in lodes? Third, why are these heavy masses which, from
their specific gravity, should be found only at the very bottom of the
drifts, if placed there by water action, sometimes found in all
positions from the surface to the bottom of the wash? And, lastly, why
is it that when an alluvial lead is traced up to, or down from, an
auriferous reef, that the light, angular gold lies close to the reef,
while the heavy masses are often bedded much farther away? Any one who
has worked a ground sluice knows how extremely difficult it is with a
strong head of water to shift from its position an ounce of solid gold.
What, then, would be the fluvial force required to move the Welcome
Nugget? Under certain circumstances, Niagara itself would not be equal
to the task.

The generally smooth appearance of alleged alluvial gold is adduced as
an argument in favour of its having been carried by water from its
original place of deposit, and thus in transit become waterworn; while
some go so far as to say that it was shot out of the reefs in a molten
state. The latter idea has been already disposed of, but if not, it may
be dismissed with the statement that the heat which would melt silica in
the masses met with in lodes would sublimate any gold contained, and
dissipate it, not in nuggets but in fumes. With regard to the assumed
waterworn appearance of alluvial gold, I have examined with the
microscope the smooth surface of more than one apparently waterworn
nugget, and found that it was not scratched and abraded, as would have
been the case had it been really waterworn, but that it presented the
same appearance, though infinitely finer in grain, as the surface of a
piece of metal fresh from the electrical plating-bath.

Let us then try if we cannot suggest, if not a complete answer to the
many perplexing problems which trouble the alluvial miner, at least a
theory that will bear investigation, and by the application of which
many apparent paradoxes may be explained. While admitting that certain
alluvial gold has been ground out of its siliceous matrix, and
distributed and re-collected by water action, we may inquire what would
be the result if we extend the experiment of the boy and knife, or the
electro-metallurgical bath to alluvial drifts, and show that it is not
only possible, but almost certain, that similar action has obtained, and
may now be occurring.

Mr. Daintree, of the Victorian Geological Survey, many years ago
discovered accidentally that gold chloride would deposit its metal on a
metallic base in the presence of any organic substance. Mr. Daintree
found that a piece of undissolved gold in a bottle containing chloride
of gold in solution had, owing to a portion of the cork having fallen
into the liquid, grown or accretionised so much that it could not be
extracted through the neck. This led Mr. Charles Wilkinson, who has
contributed much to our scientific knowledge of metallurgy, to
experiment further in the same direction. He says: “Using the most
convenient salt of gold, the terchloride, and employing wood as the
decomposing agent, in order to imitate as closely as possible the
organic matter supposed to decompose the solution circulating through
the drifts, I first immersed a piece of cubic iron pyrites taken from
the coal formation of Cape Otway, far distant from any of our gold
rocks, and therefore less likely to contain gold than other pyrites. The
specimen (No. 1) was kept in dilute solution for about three weeks, and
is completely covered with a bright film of gold. I afterwards filed off
the gold from one side of a cube crystal to show the pyrites itself and
the thickness of the surrounding coating, which is thicker than ordinary
notepaper. If the conditions had continued favourable for a very
lengthened period, this specimen would doubtless have formed the nucleus
of a large nugget. Iron, copper, and arsenical pyrites, antimony,
galena, molybdenite, zinc blende, and wolfram were treated in the above
manner with similar results. In the above experiments a small chip of
wood was employed as the decomposing agent. In one instance I used a
piece of leather. All through the wood and leather gold was disseminated
in fine particles, and when cut through the characteristic metallic
lustre was brightly reflected. The first six of these sulphides were
also operated upon simply in the solution without organic matter, but
they remained unaltered.”

Wilkinson found that when the solution of gold chloride was as strong
as, say, four grains to the ounce of water, that the pyrites or other
base began to decompose, and the iron sulphide changed to yellow oxide,
the “gossan” of our lodes, and that though the gold was deposited, this
occurred in an irregular way, and it was coated with a dark brown
powdery film something like the “black gold,” often found in drifts
containing much ferruginous matter. Such were the curious Victorian
nuggets Spondulix and Lothair.

Professor Newbery also made a number of similar experiments, and arrived
at like results. He states as follows: “I placed a cube of galena in a
solution of chloride of gold, with free access of air, and put in
organic matter; gold was deposited as usual, in a bright metallic film,
apparently completely coating the cube. After a few months the film
burst along the edges of the cube, and remained in that state with the
cracks open without any further alteration in size or form being
apparent. Upon removing it a few days ago and breaking it open, I found
that a large portion of the galena had been decomposed, forming chloride
and sulphate of lead and free sulphur, which were mixed together,
encasing a small nucleus of undecomposed sulphate of lead. The formation
of these salts had exerted sufficient force to burst open the gold
coating, which upon the outside had the mammillary form noticed by
Wilkinson, while the inside was rough and irregular with crystals
forcing their way into the lead salts. Had this action continued
undisturbed, the result would have been a nugget with a nucleus of lead
salts, or if there had been a current to remove the results of the
decomposition, a nugget without a nucleus of foreign matter.”

But Newbery also made another discovery which still further establishes
the probability of the accretionary growth of gold in drifts. In the
first experiments both investigators used organic substances as the
reagent to cause the deposit of gold on its base, and in each case these
substances whether woodchips, leather, or even dead flies, were found to
be so absolutely impregnated with gold as to leave a golden skeleton
when afterwards burned. Timber found in the Ballarat deep leads has been
proved to be similarly impregnated.

Newbery found that gold could also be deposited on sulphurets without
any other reagent. He says: “In our mineral sulphurets, however, we have
agents which are not only capable of reducing gold and silver from
solution, but besides are capable of locating them when so reduced in
coherent and bulky masses. Thus the aggregation of the nuggety forms of
gold from solution becomes a still more simple matter, only one reagent
being necessary, so that there is a greater probability of such
depositions obtaining than were a double process necessary. Knowing the
action of sulphides, the manner or the mode of formation of a portion at
least of these nuggets seems apparent. Conceive a stream or river fed by
springs rising in a country intersected by auriferous reefs, and
consequently in this case carrying gold in solution; the drift of such a
country must be to a greater or lesser extent pyritous, so that the
_débris_ forming the beds of these streams or rivers will certainly
contain nodules of such matters disseminated or even stopping them in
actual contact with the flow of water. It follows, then, from what has
been previously affirmed, that there will be a reduction of gold by
these nodules, and that the metal thus reduced will be firmly attached
to them, at first in minute spangles isolated from each other, but
afterwards accumulating and connecting in a gradual manner at that point
of the pyritous mass most subject to the current until a continuous film
of some size appears. This being formed the pyrites and gold are to a
certain extent polarised, the film or irregular but connected mass of
gold forming the negative, and the pyrites the positive end of a voltaic
pair; and so according as the polarisation is advanced to completion the
further deposition of gold is changed in its manner from an
indiscriminate to an orderly and selective deposition concentrated upon
the negative or gold plate. The deposition of gold being thus
controlled, its loss by dispersion or from the crumbling away of the
sustaining pyrites is nearly or quite prevented, a conservative effect
which we could scarcely expect to obtain if organic matter were the
reducing agent. Meanwhile there is a gradual wasting away of the pyrites
or positive pole, its sulphur being oxidised to sulphuric acid and its
iron to sesquioxide of iron, or hematite, a substance very generally
associated with gold nuggets. According to the original size of the
pyritous mass, the protection it receives from the action of oxidising
substances other than gold, the strength of the gold solution, length of
exposure to it, the rate of supply and velocity of stream, will be the
size of the gold nugget. As to the size of a pyritous mass necessary to
produce in this manner a large nugget, it is by no means considerable. A
mass of common pyrites (bisulphide of iron) weighing only 12 lbs. is
competent for the construction of the famous ‘Welcome Nugget,’ an
Australian find having weight equal to 152 lbs. avoirdupois. Such masses
of pyrites are by no means uncommon in our drifts or the beds of our
mountain streams. Thus we find that no straining of the imagination is
required to conceive of this mode of formation for the huge masses of
gold found in Australia in particular, such as the Welcome Nugget, 184
lbs. 9 oz.; the Welcome Stranger, a surface nugget, 190 lbs. after
smelting; the Braidwood specimen nugget, 350 lbs., two-thirds gold;
besides many other large masses of almost virgin gold which have been
obtained from time to time in the alluvial diggings.”

The author has made a number of experiments in the same direction, but
more with the idea of demonstrating how possibly gold may in certain
cases have been deposited in siliceous formations after such formations
had solidified. Some of the results were remarkable and indeed
unexpected. I found that I could produce artificial specimens of
auriferous quartz from stone which had previously contained no gold
whatever, also that it was not absolutely necessary that the stone so
treated should contain any metallic sulphides.

The following was contributed by the author and is from the
“Transactions” of the Australasian Institute of Mining Engineers for
1893:--

    “THE DEPOSITION OF GOLD.

    “The question as to how gold was originally deposited in our
    auriferous lodes is one to which a large amount of attention has
    been given, both by mineralogists and practical miners, and
    which has been hotly argued by those who held the igneous theory
    and those who pronounced for the aqueous theory. It was held by
    the former that as gold was not probably existent in nature in
    any but its metallic form, therefore it had been deposited in
    its siliceous matrix while in a molten state, and many ingenious
    arguments were adduced in support of this contention. Of late,
    however, most scientific men, and indeed many purely empirical
    inquirers (using the word empirical in its strict sense) have
    come to the conclusion that though the mode in which they were
    composed was not always identical, all lodes, including
    auriferous formations, were primarily derived from
    mineral-impregnated waters which deposited their contents in
    fissures caused either by the cooling of the earth’s crust or by
    volcanic agency.

    “The subject is one which has long had a special attraction for
    the writer, who has published several articles thereon, wherein
    it was contended that not only was gold deposited in the lodes
    from aqueous solution, but that some gold found in form of
    nuggets had not been derived from lodes but was nascent in its
    alluvial bed; and for this proof was afforded by the fact that
    certain nuggets have been unearthed having the shape of an
    adjacent pebble or angular fragment of stone indented in them.
    Moreover, no true nugget of any great size has ever been found
    in a lode such as the Welcome, 2159 oz., or the Welcome
    Stranger, 2280 oz.; while it was accidentally discovered some
    years ago that gold could be induced to deposit itself from its
    mineral salt to the metallic state on any suitable base, such as
    iron sulphide.

    “Following out this fact, I have experimented with various salts
    of gold, and have obtained some very remarkable results. I have
    found it practicable to produce most natural looking specimens
    of auriferous quartz from stone which previously, as proved by
    assay, contained no gold whatever. Moreover, the gold, which
    penetrates the stone in a thorough manner, assumes some of the
    more natural forms. It is always more or less mammillary, but at
    times, owing to causes which I have not yet quite satisfied
    myself upon, is decidedly dendroidal, as may be seen in one of
    the specimens which I have submitted to members. Moreover, I
    find it possible to moderate the colour and to produce a
    specimen in which the gold shall be as ruddy yellow as in the
    ferro-oxide gangue of Mount Morgan, or to tone it to the pale
    primrose hue of the product of the Croydon mines.

    “I note that the action of the bath in which the stone is
    treated has a particularly disintegrating effect on many of the
    specimens. Some, which before immersion were of a particularly
    flinty texture, became in a few weeks so friable that they could
    be broken up by the fingers. So far as my experiments have
    extended they have proved this, that it was not essential that
    the silica and gold should have been deposited at the one time
    in auriferous lodes. A non-auriferous siliceous solution may
    have filled a fissure, and, after solidifying, some volcanic
    disturbance may have forced water impregnated with a gold salt
    through the interstices of the lode formation, when, if the
    conditions were favourable, the gold would be deposited in
    metallic forms. I prefer, for reasons which will probably be
    understood, not to say exactly by what process my results are
    obtained, but submit specimens for examination.

    “(1) Piece of previously non-gold bearing stone. Locality near
    Adelaide, now showing gold freely in mammillary and dendroidal
    form.

    “(2) Stone from New South Wales, showing gold artificially
    introduced in interstices and on face.

    “(3) Stone from West Australia, very glassy looking, now
    thoroughly impregnated with gold; the mammillary formation
    being particularly noticeable.

    “(4) Somewhat laminated quartz from Victoria, containing a
    little antimony sulphide. In this specimen the gold not only
    shows on the surface but penetrates each of the laminations, as
    is proved by breaking.

    “(5) Consists of fragments of crystallised carbonate of lime
    from Tarrawingee, in which the gold is deposited in spots, in
    appearance like ferrous oxide, until submitted to the magnifying
    glass.

    “The whole subject is worthy of much more time than I can
    possibly give it. The importance lies in this: That having found
    how the much desired metal may have been deposited in its
    matrix, the knowledge should help to suggest how it may be
    economically extracted therefrom.”

A very remarkable nugget weighing 16¾ oz. was sluiced from near the
surface in one of my own mining properties at Woodside, South Australia,
some years ago, which illustrated the nuclear theory very beautifully.
This nugget is very irregular in shape, fretted and chased as though
with a jeweller’s graving tool, showing plainly the shape of the
pyritous crystals on which it was formed while the interstices were
filled with red hematite iron just as found in artificially formed
nuggets on a sulphide of iron base. The author has a nugget from the
same locality weighing about 1½ oz. which exhibits in a marked degree
the same characteristics, as indeed does most of the alluvial gold found
in the Mount Lofty Ranges; also a nugget from near the centre of
Australia weighing four ounces, in which the original crystals of
pyrites are reproduced in gold just as an iron horse-shoe, placed in a
launder through which cupriferously impregnated water flows, will in
time be changed to nearly pure copper and yet retain its shape.

Now with regard to the points I have put (p. 36) as to the apparent
anomalies of occurrence of alluvial gold. The explanation for alluvial
gold being of finer quality as a rule than reef is probably that while
gold and silver, which have a considerable affinity for each other, were
presumably dissolved from their salts and held in solution in the same
mineral water, they would in many cases not be deposited together, for
the reason that silver is most readily deposited in the presence of
alkalies, which would be found in excess in mineral waters coming direct
from the basic rocks, while gold is induced to precipitate more quickly
in acid solutions, which would be the character of the waters after they
had been exposed to atmospheric action and to contact with organic
matters.

This, then, may explain not only the comparatively greater purity of the
alluvial gold, but also why big nuggets are found so far from auriferous
reefs, and also why heavy masses of gold have been frequently unearthed
from among the roots even of living trees, but more particularly in
drifts containing organic matter, such as ancient timber.

All, then, that has been adduced goes to establish the belief that the
birthplace of our gold is in certain of the earlier rocks comprising the
earth’s crust, and that its appearance as the metal that is valued so
highly is the result of electro-chemical action, such as we can
demonstrate in the laboratory.




    CHAPTER VI

    GOLD EXTRACTION


We now come to a highly important part of our subject, the practical
treatment of ores and matrixes for the extraction of the metals
contained. The methods employed are multitudinous, but may be divided
into four classes, namely, washing, amalgamating with mercury,
chlorinating, cyaniding and other leaching processes, and smelting. The
first is used in alluvial gold and tin workings and in preparing some
silver, copper, and other ores for smelting, and consists merely in
separating the heavier metals and minerals from their gangues by their
greater specific gravity in water. The second includes the trituration
of the gangue and the extraction of its gold or silver by means of
mercury. Chlorinating and leaching generally is a process whereby metals
are first changed by chemical action into their mineral salts, as
chloride of gold, nitrate of silver, sulphate of copper, and being
dissolved in water are afterwards re-deposited in the metallic form by
means of well-known reagents.

In really successful mining it is in the last degree important that the
mode of extraction of metals in the most scientific manner should be
thoroughly understood, but as a general rule the science of metallurgy
is but very superficially grasped even by those whose special business
it is to treat ore bodies in order to extract their metalliferous
contents, and whether in quartz crushing mill, lixiviating, or smelting
works there is much left to be desired in the method of treating our
ores.

My attention was recently attracted to an article written by Mr. F. A.
H. Rauft, M.E., from which I make the following extract:

    He says, speaking of the German treatment of ores and the mode
    of procedure in Australia, “It is high time that Government stepped
    in and endeavoured by prompt and decisive action to bring the mining
    industry upon a sound and legitimate basis. Though our ranges abound
    in all kinds of minerals that might give employment to hundreds of
    thousands of people, mining is carried on in a desultory, haphazard
    fashion. There is no system, and the treatment of ores is of
    necessity handed over to the tender mercies of men who have not even
    an idea of what an intricate science metallurgy has become in older
    countries. During many years of practical experience I have never
    known a single instance where a lode, on being worked, gave a return
    according to assay, and I have never known any mine where some of
    the precious metals could not be found in the tailings or slag. The
    Germans employ hundreds of men in working for zinc which produces
    some two or three per cent. to the ton; here the same percentage of
    tin could hardly be made payable, and this, mark you, is owing not
    to cheaper labour alone, but chiefly to the labour-saving appliances
    and the results of the researches of such gigantic intellects
    as Professor Kerl and many others, of whom we in this country
    never even hear. Go into any of the great mining works of central
    Germany, and you may see acres covered by machinery ingeniously
    constructed to clean, break, and sort, and ultimately deliver the
    ores into trucks or direct into the furnace, and the whole under the
    supervision of a youngster or two. When a parcel of ore arrives at
    any of the works, say Freiberg or Clausthal, it is carefully assayed
    by three or four different persons and then handed over to practical
    experts, who are expected to produce the full amount of precious
    metal according to assay; and if by any chance they do not, a fixed
    percentage of the loss is deducted from their salary; or, if the
    result is in excess of this assay which is more frequently the case,
    a small bonus is added to their pay. Compare this system with our
    own wasteful, reckless method of dealing with our precious metals,
    and we may hide our heads in very shame.”

All really practical men will, I think, endorse Mr. Rauft’s opinion.
Well organised and conducted schools of mines will gradually ameliorate
this unsatisfactory state of things, and I hope before long that we
shall have none but qualified certificated men in our mines. In the
meantime a few practical hints, particularly on that very difficult
branch of the subject, the saving of gold, will, it is hoped, be found
of service.

The extraction of gold from the soil is an industry so old that its
first introduction is lost in the mist of ages. As before stated, gold
is one of the most widely disseminated of the metals, and man, so soon
as he had risen from the lowest forms of savagery, began to be attracted
by the kingly metal, which he found to be easily fashioned into articles
of ornament and use, and to be practically non-corrodable.

What we now term the dish or pan, then, doubtless generally a wooden
bowl, was the appliance first used; but they had also an arrangement,
somewhat like our modern blanket tables, over which the auriferous sand
was passed by means of a stream of water. The sands of some of the
rivers from which portions of the gold supply of the old world was
derived are still washed over year after year in exactly the same
manner as was employed, probably, thousands of years ago, the labour,
very arduous, being often carried on by women, who, standing knee
deep in water, pan off the sand in wooden bowls much as the digger in
modern alluvial fields does with his tin dish. The resulting gold often
consists of but a grain or two of fine gold-dust, which is carefully
collected in quills, and so exported or traded for goods.

The digger of to-day having discovered payable alluvial dirt at such a
depth as to permit of its being profitably worked by small parties of
men with limited or no capital, procures first a half hogshead for a
puddling tub, a “cradle,” or “long tom,” and tin dish. The “wash dirt,”
as the auriferous drift is usually termed, contains a considerable
admixture of clay of a more or less tenacious character, and the bulk of
this has to be puddled and so disintegrated before the actual separation
of the gold is attempted in the cradle or dish. This is done in the tub
by constantly stirring with a shovel, and changing the water as it
becomes charged with the floating argillaceous, or clayey, particles.
The gravel is then placed in the hopper of the cradle which separates
the larger stones and pebbles, the remainder passing down over inclined
ledges as the cradle is slowly rocked and supplied with water. At the
bottom of each ledge is a riffle to arrest the particles of gold.
Sometimes, when the gold is very fine, amalgamated copper plates are
introduced and the lower ledges are covered with green baize to act as
blanket tables and catch gold which might otherwise be lost.

A long tom (Fig. 8) is a trough some 12 feet in length by 20 inches in
width at the upper end, widening to 30 inches at the lower end; it is
about 9 inches deep and has a fall of 1 inch to a foot. An iron screen
is placed at the lower end (cut off in the manner shown in diagram)
where large stones are caught, and below this screen is the riffle box,
12 feet long, 3 feet wide, and having the same inclination as the upper
trough. It is fitted with several riffles in which mercury is sometimes
placed.

    [Illustration: FIG. 8. LONG TOM.]

Much more work can be done with this appliance than with the cradle,
which it superseded. Of course, the gold must be coarse and water
plentiful.

When, however, the claim is paying, and the diggings show signs of some
permanency, a puddling machine is constructed. This is described and
illustrated in Chapter XII., called “Rules of Thumb.”

Hydraulicing and ground sluicing is a very cheap and effective method of
treating large quantities of auriferous drift, and, given favourable
circumstances, such as a plentiful supply of water with good fall and
extensive loose auriferous deposits, a very few grains to the ton or
load can be made to give payable returns.

    [Illustration: FIG. 9. FLUME, GREAT SOUTHERN GOLD-FIELD,
    SHOALHAVEN, N.S.W.]

    [Illustration: FIG. 10. MONITOR AT WORK, GREAT SOUTHERN
    GOLD-FIELD.]

The water is conveyed in flumes (Fig. 9), or pipes to a point near
where it is required, thence in wrought iron pipes gradually reduced
in size and ending in a great nozzle somewhat like that of a fireman’s
hose. The “Monitor,” as it is sometimes called, is generally fixed on a
movable stand, so arranged that the strong jet of water can be directed
to any point by a simple adjustment (Fig. 10). A “face” is formed in
the drift, and the water played against the lower portion of the ledge,
which is quickly undermined, falls, and is soon washed away in the
stream of water, which is conducted through sluices with riffles, and
sometimes over considerable lengths of amalgamated copper plates. This
class of mining has been most extensively carried out in California and
New Zealand, and some districts of Victoria, but the truly enormous
drifts of the Shoalhaven district in New South Wales must in the
near future add largely to the world’s gold supply. These drifts are
auriferous from grass roots to bed rock, extend for nearly fifty miles,
and are in places as much as 300 feet deep. Want of capital and want of
knowledge has hitherto prevented them being profitably worked on a large
scale.

The extraction of reef gold from its matrix is a much more complicated
process, and the problem how most effectively to obtain that great
desideratum--a complete separating and saving operation--is one which
taxes the skill and evokes the ingenuity of scientific men all over the
world. The difficulty is that as scarcely any two gangues, or matrixes,
are exactly alike, the treatment which is found most effective on one
mine will often not answer in another. Much also depends on the
proportion of gold to the ton of rock under treatment, as the most
scientific and perfect processes of lixiviation hitherto adopted will
not pay, even when all other conditions are favourable, if the amount of
gold is much under half an ounce to the ton and even then will leave but
a very small profit. If, however, the gold is “free,” and the lode
large, a very few pennyweights (or “dollars,” as the Americans say) to
the ton will pay handsomely. The mode of extraction longest in vogue,
and after all the cheapest and most effective, for free milling ores
where the gold is not too fine, is amalgamation with mercury, which
metal has a strong affinity for gold, silver, and copper.

As to crushing appliances, I shall not say much. “Their name is legion
for they are many,” and the same may be said of concentrators. It may be
old-fashioned, but I admit my predilection is still in favour of the
stamper-battery, for the reason that though it may be slower in
proportion to the power employed, it is simple and not liable to get
out of order, a great advantage when one has so often to depend on men
who bring to their work a supply principally of main strength and
stupidity. For the same reason I prefer the old draw and lift, and
plunger pumps to newer but more complicated water-lifters.

On both these points, however, I am constrained to admit that my opinion
has recently been somewhat shaken.

I have lately seen two appliances which appear to mark a new era in the
scientific progress of mining. One is the “Griffin Mill,” the other the
“Lemichel Siphon Élévateur.”

The first is in some respects on the principle of the Huntingdon Mill.
The latter, if the inventor is to be believed, and the results seem to
show he may, will be a wonderful factor in developing not only mining
properties where a preponderance of water is the trouble, but also in
providing an automatic, and therefore extremely cheap, mode of
water-raising and supply, which in simplicity is thus far unexampled.
Atmospheric pressure alone is relied on. The well-known process of the
syphon is the basis, but with this essential difference, that a large
proportion of the water drawn up to the apex of the syphon is
super-elevated to heights regulated by the fall obtained in the outlet
leg. This elevation can be repeated almost indefinitely by returning the
waste water to the reservoirs.

The Lemichel Syphon (Fig. 11) is a wonderful, yet most simple
application of natural force. The inlet leg of the syphon is larger in
diameter than the outlet leg, and is provided at the bottom with a valve
or “clack.” The outlet leg has a tap at its base. At the apex are two
chambers, with an intermediary valve, regulated by a counterpoise
weighted lever. The first chamber has also a vertical valve and pipe.

When the tap of the outlet leg is turned, the water flows as in an
ordinary syphon, but owing to the rapid automatic opening and shutting
of the valve in the first chamber about 45 per cent. of the water is
diverted, and may be raised to a height of many feet above the top of
the syphon.

It need not be impressed on practical men that if this invention will
perform anything like what is claimed for it, its value can hardly be
calculated. After a careful inspection of the appliance in operation, I
believe it will do all that is stated.

Another invention is combined with this which, by a very small
expenditure of fuel, will enable the first point of atmospheric pressure
to be attained. In this way the unwatering of mines may be very
inexpensively effected, or water for irrigation purposes may be raised
from an almost level stream (Fig. 11).

    [Illustration: FIG. 11. “LEMICHEL” SYPHON.]

    [Illustration: FIG. 12. “GRIFFIN” MILL.]

The Griffin Mill is a centrifugal motion crusher with one roller only,
which, by an ingenious application of motive force, revolves in an
opposite direction to its initial momentum, and which evolves a force of
6000 lb. against the tire, which is only 30 inches in diameter. For hard
quartz the size should be increased by at least 6 inches. It is claimed
for this mill that it will pulverise to a gauge of 900 holes to the
square inch from 1½ to 2½ tons per hour, or, say roughly, 150 tons
per week.

The Huntingdon mill (Fig. 13) is a good crusher and amalgamator where
the material to be operated on is comparatively soft, but does not do
such good work when the stone is of a hard flinty nature.

    [Illustration: FIG. 13. HUNTINGDON MILL.]

A No. 4 Dodge stone-breaker working about 8 hours will keep a five foot
Huntingdon Mill going 24 hours, and an automatic feeder is necessary.
For that matter both are almost essential for an ordinary stamper
battery, and will certainly increase the crushing capacity and do better
work from the greater regularity of the feed.

A 10 h.-p. (nominal) engine of good type is sufficient for Huntingdon
mill, rock breaker, self-feeder and steam pump. A five foot mill under
favourable circumstances will crush about as much as eight head of
medium weight stamps.

    [Illustration: FIG. 14. STONE-BREAKER.]

    [Illustration: FIG. 15. STONE-BREAKER (SECTIONAL VIEW).]

The Grusonwerk Ball Mills (Fig. 16), made by Krupp of Germany, as also
that made by the Austral Otis Company, Melbourne, are fast and excellent
triturating appliances for either wet or dry working, but are specially
suitable only for ores when the gold is fine and evenly distributed
in the stone. The trituration is effected by revolving the stone in a
large cylinder together with a number of steel balls of various sizes,
the attrition of which with the rock quickly grinds it to powder of any
required degree of fineness.

    [Illustration: FIG. 16. GRUSONWERK BALL MILL.]

Probably more mines have been ruined by bad mill management than by bad
mining, though every experienced man must have seen in his time many
most flagrant instances of bungling in the latter respect. Shafts are
often sunk on the wrong side of the lode or too near or too far away
therefrom, while instances have not been wanting where the (mis)manager
has, after sinking his shaft, driven in the opposite direction to that
where the lode should be found.

A common error is that of erecting machinery before there is sufficient
ore in sight to make it certain that enough can be provided to keep the
plant going. In mines at a distance from the centre of management it is
almost impossible to check mistakes of this description, caused by the
ignorance or over sanguineness of the mine superintendent, and they are
often as disastrous as they are indefensible. Another fertile source of
failure is the craze for experimenting with untried inventions, alleged
to be improvements on well-known methods.

A rule in the most scientific of card games, whist, is “when in doubt
lead trumps.” It might be paraphrased for mining thus: “When in doubt
about machinery use that which has been proved.” Let some one else do
the experimenting.

    [Illustration: FIG. 17. DOUBLE FAULTED LODE.]

The success of a quartz mine depends as much on favourable working
conditions as on its richness in gold. Thus it may be that a mine
carrying 5 or 6 oz. of gold to the ton but badly circumstanced as to
distance, mountainous roads, lack of wood and water, in some cases a
plethora of the latter, or irregularly faulted country (Fig. 17), may
be less profitable than another showing only 5 or 6 dwt., but favourably
situated.

It is usually desirable to choose for the battery site, when possible,
the <DW72> of a hill which consists of rock that will give a good
foundation for your battery.

The economical working depends greatly on the situation, which is
generally fixed more or less, in the proximity of the water. The
advantages of having ample water for battery purposes, or of using water
as a motive power, are so great that it is very often desirable to
construct a tramway of considerable length, when, by so doing, that
power can be utilised; hence most quartz mills are placed near streams,
or in valleys where catchment dams can be effectively constructed,
except, of course, in districts where much water has to be pumped from
the mine.

If water-power can be used, the water-motor will necessarily be placed
as low as possible, in order to obtain the fullest available power. One
point is essential. Special care must be taken to keep the appliances
above highest flood-level. If the water in the stream is not sufficient
to carry off the tailings, the battery should be placed at such a height
as to leave sufficient <DW72> for tailings’ dumps. This is more important
when treating ore of such value that the tailings are worth saving for
secondary treatment. In this case provision should be made for tailings,
dams, or slime pits.

Whether the battery is worked by water, steam, or gas power, an ample
supply of water is absolutely necessary, at least until some thoroughly
effective mode of dry treatment is established. If it can be possibly
arranged the water should be brought in by gravitation, and first cost
is often least cost; but where this is impossible, pumps of sufficient
capacity, not only to provide the absolute quantity used, but to meet
any emergency, should be erected.

The purer the water the better it will be for amalgamating purposes, and
in cold climates it is desirable to make provision for heating the water
supplied to the battery. This can be done by means of steam from the
boiler led through the feed tanks; but where the boiler power is not
more than required, waste steam from the engine may be employed, but
care must be taken that no greasy matter comes in contact with the
plates. The exhaust steam from the engine may be utilised by carrying it
through tubes fitted in an ordinary 400 gallon tank.

Reducing appliances have often to be placed in districts where the water
supply is insufficient for the battery. When this is so every available
means must be adopted for saving the precious liquid, such as condensing
the exhaust steam from the engine. This may be done by conducting it
through a considerable length of ordinary zinc piping, such as is used
for carrying the water from house roofs. Also tailings pits should be
made, in which the tailings and slimes are allowed to settle, and the
cleared water is pumped back to be again used. These pits should, where
practicable, be cemented. It is usual, also, to have one or two tailings
dams at different levels; the tailings are run into the upper dam, and
are allowed to settle; the slimes overflow from it into the lower dam,
and are there deposited, while the cleared water is pumped back to the
battery. Arrangements are made by which all these reservoirs can be
sluiced out when they are filled with accumulated tailings. It is well
not to leave the sluicing for too long a period, as when the slimes and
tailings are set hard they are difficult to remove.

Where a permanent reducing plant is to be erected, whatever form of mill
may be adopted, it is better for many reasons to use automatic ore
feeders. Of these the best two I have met are the “Tulloch” (Fig. 18),
and “Challenge” (Fig. 19) either of which can be adapted to any mill and
both do good work.

By their use the reducing capacity of the mill is increased, and the
feeding being regular the wear and tear is decreased, while by the
regulated feeding of the “pulp” in the battery box or mortar can be
maintained at any degree of consistency which may be found desirable,
and thus the process of amalgamation will be greatly facilitated. The
only objection which can be urged against the automatic feeder is that
the steel points of picks, gads, drills, and other tools may be allowed
to pass into the mortar or mill, and thus cause considerable wear and
tear. A remedy for this is suggested (p. 148).

    [Illustration: PLATE IV.--TAIL RACE _To face p._ 74]

    [Illustration: FIG. 18. TULLOCH AUTOMATIC ORE FEEDER.]

    [Illustration: FIG. 19. CHALLENGE AUTOMATIC ORE FEEDER.]

If local conditions are favourable and the management good, some mines
have paid well with a yield of from 1½ to 4 dwts. of gold per ton of
ore; but others have not paid with much higher yields in test crushings.
Great judgment is required in selecting the best possible site for the
class of crushing machinery decided upon. The crusher should be as high
as can be managed so as to give a good clear run for the tailings and
room for the concentrators and amalgamators, &c., below the copper
plates and blanket strakes. Solid, strong foundations are essential;
many failures are due to a neglect of this point.

In a stamp mill (Fig. 20) the foundations are usually made of hard-wood
logs about 5 to 6 feet long, set on end, the bottom end resting on rock
and set round with cement concrete. These are bolted together, and the
“box” or mortar is bolted to them. The horizontal logs to carry the
“horses” or supports for the battery frame should also be of good size,
and solidly and securely bolted. The same applies to your engine bed,
but whether it be of timber, or mason work, above all things provide
that the whole of your work is set out square and true to save after
wear and friction. Fig. 21 represents a 10-head stamp mill.

My experience has been that the most effective weight for stamps and
height for drop largely depends on the nature of the rock foundation. I
have usually found that with medium stamps, say 7½ to 8 cwt. with
fair drop and lively action, about 80 falls per minute, the best results
were obtained, but the tendency of modern mill men is towards the
heavier stamps, 10 cwt. and even heavier.

Great improvements have been made in stamp mills since the sixteenth
century, as is evident by comparing Fig. 21A with Figs. 20 and 21; even
in the writer’s time they have been considerable.

To find the horse power required to drive a battery, multiply the weight
of one stamp by the number of stamps in the battery; the height of lift
in feet by the number of lifts per minute; add one-third of the product
for friction, and the result will be the number of feet-lbs. per minute;
divide this by 33,000 which is the number of feet-lbs. per minute equal
to 1 h.-p. and the result will be the h.-p. required. Thus if a stamp
weighs 800 lbs. and you have five in the box, and each stamp has a
lift of 9 in. = 0·75 ft. and strikes 80 blows per minute, then ÷ 800
× 5 × 0·75 × 80 = 240,000; one third of 240,000 = 80,000, which added
to 240,000 = 320,000; and 320,000 divided by 33,000 = 9·7 h.-p. or 1·9
h.-p. each stamp.

    [Illustration: FIG. 20. STAMP MILL, SHOWING PART OF FOUNDATIONS.]

    [Illustration: FIG. 21. 10-HEAD STAMP MILL.]

The total weight of a battery, including stamper box, stampers, &c, may
be roughly estimated at about 1 ton per stamp. Medium weight stampers,
including shank, cam, disc, head, and shoe, weigh from 600-700 lbs., and
need about 3/4 h.-p. to work them.

    [Illustration: FIG. 21A. SIXTEENTH CENTURY STAMP MILL.]

The quantity of water required for the effective treatment of gold
bearing rock in a stamper battery varies according to the composition of
the material to be operated upon, but generally it is more than the
inexperienced believe. For instance, “mullocky” lode stuff, containing
much clayey matter or material carrying a large percentage of heavy
metal, such as titanic iron or metallic sulphides, will need a larger
quantity of water per stamp than clean quartz. A fair average quantity
would be 750 to 1000 gallons per hour for each box of five stamps. In
general practice I have seldom found 1000 gallons per hour more than
sufficient.

As to the most effective mesh for the screen or grating, that depends
largely on the size of the gold particles contained in the gangue. The
finer the particles the closer must be the mesh, so that nothing but
careful experiment will enable the battery manager to decide this most
important point. The American slotted screens are best; they wear better
than the punched gratings and can be used of finer gauge. Woven steel
wire gauze is employed with good effect in some mills where specially
fine trituration is required. This class of screen requires special care
as it is somewhat fragile, but with intelligent treatment does good
work.

The fall or inclination of the tables, both copper and blanket strakes,
is also regulated by the class of ore. If it should be heavy then the
fall must be steeper. A fair average drop is 3/4 inch to the foot. Be
careful that your copper tables are thoroughly water-tight, for,
remember, where water will percolate, mercury will penetrate.

The blanket tables are simply a continuation of the mercury tables, but
covered with strips of coarse blanket, green baize, or other flocculent
material, intended to arrest the heavier metallic particles which have
not been amalgamated.

The blanket table is, however, a very unsatisfactory concentrator at
best, and is giving place to mechanical concentrators of various
descriptions.

I have a device at present unpatented which will do away with the
necessity for blanket tables or copper plates, as by the expenditure of
from 1/2 to 1 h.-p. every particle of free gold after leaving the boxes
must come within the embrace of a mercury amalgam. No cleaning of plates
is required.

An ancient Egyptian gold washing table is shown in Fig. 22. It is a
representation of an old stone table such as is referred to in p. 2,
which was used by the Egyptians in treating the gold ores of Lower
Egypt. The ore was first ground, it is likely by means of some
description of stone arrastra, and then passed over the sloping table
with water, the gold being retained in the riffles. In these the
material would probably be mechanically agitated. Although for its era
ingenious it will be plain to practical men that if the gold were fine
the process would be very ineffective. Possibly, but of this I have no
evidence, mercury was used to retain the gold in the riffles, for, as
previously stated, this method was known to the ancients.

    [Illustration: FIG 22. WASHING TABLE OF STONE WITH RIFFLES.]

At a mine at which I was managing director the lode was almost entirely
composed of sulphide of iron, carbonate of lime or calcspar, with a
little silica. In this case it was found best to crush without mercury,
then run the pulp into pans, where it was concentrated. The concentrates
were calcined in a common reverberatory furnace, and afterwards
amalgamated with mercury in a special pan; the results were very
satisfactory; but it does not follow that this process would be the most
suitable for a slightly different lode stuff.

I was lately consulted with respect to the treatment of a pyritic ore in
a very promising mine, but could not recommend the above treatment,
because though the pyrites in the gangue was similar, the bulk of the
lode consisted of silica, consequently there would be a great waste of
power in triturating the whole of the stuff to what, with regard to much
of it, would be an unnecessary degree of fineness. I am of opinion that
in cases such as this, where it is not intended to adopt the
chlorination or cyanogen process, it will be found most economical to
crush to a coarse gauge, concentrate, calcine the concentrates, and
finally amalgamate in some suitable amalgamator.

Probably for this mode of treatment Krom rolls would be found more
effective reducing agents than stampers, as with them the bulk of the
ore can be broken to any required gauge and there would consequently be
less loss in “slimes.”

The great art in effective battery work is to crush your stuff to the
required fineness only, and then to provide that each particle is
brought into contact with the mercury either in box, trough plate, or
pan. To do this the flow of water must be carefully regulated; it should
not carry the stuff off too quickly nor allow the troughs and plates to
be choked. In cold weather the water may be warmed by passing the
feed-pipe through a tank into which the steam from the engine exhausts,
and this will be found to keep the mercury bright and lively. But be
careful no engine oil or grease mingles with the water, as grease on the
copper tables will absolutely prevent amalgamation.

The first point, then, is to effectively crush the gangue, the degree of
fineness being regulated by the fineness of the gold itself. This being
done, then comes the question of saving the gold. If the quartz be
clean, and the gold unmixed with base metal, the difficulty is small.
All that is required is to ensure that each particle of gold shall be
taken up by the mercury. The main object is to arrest the gold at the
earliest possible stage; therefore, if you are treating clean stone
containing free gold, either coarse or fine, I advise the use of mercury
in the boxes, for the reason that a considerable proportion of the gold
will be caught thereby, and settling to the bottom, or adhering to
amalgamated plates in the boxes, where such are used, will not be
afterwards affected by the crushing action, which might otherwise break
up, or “flour,” the mercury. On the whole, I rather favour the use of
mercury in the box at any time, unless the ore is very refractory--that
is, contains too great a proportion of base metals, particularly
sulphides of iron, arsenic, &c., when the result will not be
satisfactory, but may entail great loss by the escape of floured mercury
carrying with it particles of gold. Intelligent experience will assist
the battery manager to adopt the right system.

The crushed stuff--generally termed the “pulp”--passes from the boxes
through the “screens” or “gratings,” and so on to the “tables”--_i.e._,
sheets of copper amalgamated on the upper surface with mercury, and
sometimes electroplated with silver and afterwards treated with mercury.
Unless the quartz is very clean, and, consequently light, I am opposed
to the form of stamper box with mercury troughs cast in the “lip,” nor
do I think that a trough under the lip is a good arrangement, as it
usually gets so choked and covered with the heavy clinging base metals
as to make it almost impossible for the gold to come in contact with the
mercury. It will be found better where the gold is fine, or the gangue
contains much base metal, to run the pulp from the lip of the battery
into a “distributor.”

The distributor is a wooden box the full width of the stamper box or
mortar, having a perforated iron bottom set some three to four inches
above the first copper plate, which should come up under the lip. The
effect of this arrangement is that the pulp is dashed on to the plate by
the falling water, and the gold at once coming in contact with the
mercury begins to accumulate and attract that which follows, till the
amalgam becomes piled in little crater-shaped mounds, and thus 75 per
cent. of the gold is saved on the top plate.

I have tried a further adaptation of this process when treating ores
containing a large percentage of iron oxide, where the bulk of the gold
is impalpably fine, and contained in the “gossan.” At the end of the
blanket table, or at any point where the crushed stuff last passes
before going to the “tailings heap” or “sludge pit,” a “saver” is
placed. The saver is a strong box about 15 in. square by 3 ft. high, one
side of which is removable, but must fit tight. Nine slots are cut
inside at 4 in. apart, and into these are fitted nine square perforated
copper plates, having about eighty to a hundred 1/4 in. holes in each;
the perforations should not come opposite each other. These plates are
to be amalgamated on both sides with mercury, and the top plate “fed”
from time to time with mercury, in which a very little sodium has been
placed. If acid ores are being treated, zinc should be employed in place
of sodium, and to prevent the plates becoming bare, if the stuff is very
poor, thick zinc amalgam may be used with good effect; but in that case
discontinue the sodium, and occasionally, if required, say once or twice
in the day, mix an ounce of sulphuric acid in a half gallon of water and
slowly pour it into the launder above the saver. Underneath the “saver”
you require a few riffles, or troughs, to catch any waste mercury, but
if not overfed there should be no waste. This automatic appliance
sometimes arrests a considerable quantity of gold.

We now come to the subsidiary processes of battery work, the “cleaning”
of plates, and “scaling” same when it is desired to get all the gold off
them, the cleaning and retorting of amalgam, and of the mercury,
smelting gold, &c.

Plates should be tenderly treated, kept as smooth as possible, and when
cleaning up after crushing, in your own battery, the amalgam--except,
say, at half-yearly intervals--should be removed with a rubber only; the
rubber is simply a square of black india-rubber or soft pine wood.

    [Illustration: FIG. 23. SCRAPER.]

When crushing rich ore, and you want to get nearly all the gold off your
plates, the scraper (Fig. 23) may be resorted to. This is usually made
by the mine blacksmith from an old flat file which is cut in half, the
top turned over, beaten out to a sharp blade, and kept sharp by touching
it up on the grinding-stone. This, if carefully used, will remove the
bulk of the amalgam without injury to the plate.

Various methods of “scaling” plates will be found among “Rules of
Thumb.”

Where base metals are present in the lode stuff frequent retortings of
the mercury, say not less than once a month, will be found to have a
good effect in keeping it pure and active. For this purpose, and in
order to prevent stoppage of the machinery, a double quantity is
necessary, so that half may be used alternately. Less care is required
in retorting the mercury than in treating the amalgam, as the object in
the one case is more to cleanse the metal of impurities than to save
gold, which will for the most part have been extracted by squeezing
through the chamois leather or calico. A good strong heat may therefore
at once be applied to the retort and continued, the effect being to
oxidise the arsenic, antimony, lead, &c., which, in the form of oxides,
will not again amalgamate with the mercury, but will either lie on its
surface under the water, into which the nozzle of the retort is
inserted, or will float away on the surface of the water. I have also
found that covering the top of the mercury with a few inches of broken
charcoal when retorting has an excellent purifying effect.

In retorting amalgam, much care and attention is required.

First, never fill the retort too full, give plenty of room for
expansion; for, when the heat is applied, the amalgam will rise like
dough in an oven, and may be forced into the discharge pipe, the
consequence being a loss of amalgam or the possible bursting of the
retort. Next, be careful in applying the heat, which should be done
gradually, commencing at the top. This is essential to prevent waste and
to turn out a good-looking cake of gold, which all battery managers like
to do, even if they purpose smelting into bars.

Sometimes special difficulties crop up in the process of separating the
gold from the amalgam. At the first “cleaning up” on the Frasers Mine at
Southern Cross, West Australia, great consternation was excited by the
appearance of the retorted gold, which, as an old miner graphically put
it, was “as black as the hind leg of a crow,” and utterly unfit for
smelting, owing to the presence of base metals. Some time after this I
was largely interested in the Blackborne mine in the same district when
a similar trouble arose. This I succeeded in surmounting, but a still
more serious one was too much for me--_i.e._, the absence of payable
gold in the stone. I give here an extract from the _Australian Mining
Standard_, of December 9th, 1893, with reference to the mode of cleaning
the amalgam which I adopted.


    NEW METHOD OF SEPARATING GOLD FROM IMPURE AMALGAM.

I had submitted to me lately a sample of amalgam from a mine in West
Australia which amalgam had proved a complete puzzle to the manager and
amalgamator. The Mint returns showed a very large proportion of
impurity, even in the smelted gold. When retorted only, the Mint
authorities refused to take it after they had treated the first two
cakes, one of 119 oz., which yielded only 35 oz. 5 dwt. standard gold,
and one of 140 oz., which gave 41 oz. 10 dwt. The gold smelted on the
mine was nearly as bad proportionately. Thus, 128 oz. smelted down at
the Mint to 87 oz. 8 dwt. and 109 oz. to 55 oz. 10 dwt. The impurity was
principally iron, a most unusual thing in my experience, and was due to
two causes revealed by assay of the ore and analysis of the mine water,
viz., an excess of arsenate of iron in the stone, and the presence in
large proportions of mineral salts, principally chloride of calcium
CaCl_{2}, sodium NaCl, and magnesium MgCl_{2}, in the mine water used in
the battery. The exact analysis of the water was as follows:--

  Carbonate of Iron             FeCO₃            2·76 grains per gallon
  Carbonate of Calcium          CaCO₃            7·61    ”         ”
  Sulphate of Calcium           CaSO₄           81·71    ”         ”
  Chloride of Calcium           CaCl₂         2797·84    ”         ”
  Chloride of Magnesium         MgCl₂          610·13    ”         ”
  Chloride of Sodium or
         Common Salt            NaCl          5072·65    ”         ”
                                             ----------
                   Total solid matter         8572·70 = 19·5 oz. to the
                                                                 gallon.

It will be seen, then, that this water is nearly four times more salt
than that of the sea. The effect of using a water of this character, as
I have previously found, is to cause the amalgamation of considerable
quantities of iron with the gold as in this case.

I received 10 oz. of amalgam, and having found what constituted its
impurities proceeded to experiment as to its treatment. When retorted on
the mine it was turned out in a black cake so impure as almost to make
it impossible to smelt properly. I found the same result on first
retorting, and after a number of experiments which need not be
recapitulated, though some were fairly effective, I hit on the following
method, which proved to be most successful and will probably be so found
in other localities where similarly unfavourable conditions prevail.

I took a small ball of amalgam, placed it in a double fold of new
fine-grained calico, and after soaking in hot water put it under a
powerful press. The weight of the ball before pressing was 1583 gr.
From this 383 gr. of mercury were expressed and five-eighths of a grain
of gold was retorted from this expressed mercury. The residue, in the
form of a dark, grey, and very friable cake, was powdered up between the
fingers and retorted, when it became a brown powder; it was afterwards
calcined on a flat sheet in the open air; result, 510 gr. of
russet- powder. Smelted with borax, the iron oxide readily
separated with the slag; result, 311 gr. gold 871-1000 fine; a second
smelting brought this up to 914-1000 fine. Proportion of smelted gold to
amalgam, one-fifth.

The principal point about this mode of treatment is the squeezing out of
the mercury, whereby the amalgam goes into the retort in the form of
powder, thus preventing the slagging of the iron and enclosure of the
gold. The second point of importance is thorough calcining before
smelting.

Of course it would be practicable, if desired, to treat the powder with
hydrochloric acid, and thus remove all the iron, but in a large way this
would be too expensive, and my laboratory treatment, though necessarily
on a small scale, was intended to be on a practical basis.

The amalgam at this mine was in this way afterwards treated with great
success.

For the information of readers who do not understand the
chemical symbols it may be said that

    FeCO₃ is carbonate of iron;
    CaCO₃ is carbonate of calcium;
    CaSO₄ is sulphate of calcium;
    CaCl₂  is chloride of calcium;
    MgCl₂ is chloride of magnesium;
    NaCl   is chloride of sodium, or common salt




    CHAPTER VII

    GOLD EXTRACTION--SECONDARY PROCESSES AND LIXIVIATION


Before any plan is adopted for treating the ore in a new mine the
management should very seriously and carefully consider the whole
circumstances of the case, taking into account the quantity and quality
of the lode stuff to be operated on, and ascertain by analysis what are
its component parts, for, as before stated, the treatment which will
yield most satisfactory results with a certain class of gangue on one
mine will sometimes, even when the material is apparently similar, prove
a disastrous failure in another. Some time since I was glad to note that
the manager of what has since become a very prominent Australian mine
strongly discountenanced the purchase of any extracting plant until he
was fully satisfied as to the character of the bulk of the ore he would
have to treat. It would be well for the pockets of shareholders and the
reputation of managers if more of our mine superintendents followed this
prudent and sensible course.

Having treated on gold extraction with mercury by amalgamated plates and
their accessories, something must be said about secondary modes of
saving in connection with the amalgamation process. The operations
described hitherto have been the disintegration of the gold-bearing
material and the extraction therefrom of the coarser free gold. But it
must be understood that most auriferous lode stuff contains a proportion
of sulphides of various metals, wherein a part of the gold, usually in a
very finely divided state, is enclosed, and on this gold the mercury has
no influence. Also many lodes contain hard heavy ferric ores, such as
titanic iron, tungstate of iron, and hematite, in which gold is held. In
others, again, are found considerable quantities of soft powdery iron
oxide or “gossan,” and compounds such as limonite, aluminous clay, &c.,
which, under the action of the crushing mill become finely divided and
float off in the water as “slimes,” carrying with them atoms of gold,
often microscopically small. To save the gold in such matrixes as these
is an operation which even the best of our mechanical appliances have
not yet fully accomplished.

Where there is not too great a proportion of base metals on which the
solvent will act, and when the material is rich enough in gold to pay
for the extra cost of treatment, chlorination or cyanisation are the
best modes of extraction yet practically adopted.

Presuming, however, that we are working by the amalgamation process, and
have crushed our stone and obtained the free gold, the next requirement
is an effective concentrator to secure the heavy base metals which hold
a percentage of gold. There are many, and some do excellent work, but do
not act equally well in all circumstances. The first and most primitive
is the blanket table (p. 79); but it can hardly be said to be very
effective, and requires constant attention and frequent changing and
washing of the strips of blanket.

Instead of blanket tables percussion tables are sometimes used, to which
a jerking motion is given against the flow of the water and pulp, and by
this means the heavier minerals are gathered towards the upper part of
the table, and are removed when concentrated. I have seen this appliance
doing fairly good work, but it is by no means a perfect concentrator.

Another form of “shaking table” is one with a lateral motion, and this,
whether with amalgamated plates, or provided with small riffles, or
covered with blanket, keeps the pulp lively and encourages the retention
of the heavier particles, whether of gold or base metals containing
gold. There has also been devised a rocking table, the action of which
is analogous to that of the ordinary miner’s cradle. This appliance,
working somewhat slowly, swings on rockers from side to side, and is
usually employed in mills where, owing to the complexity of the ore,
difficulties have been met with in amalgamating the gold. Riffles are
provided and even very fine gold is sometimes effectively recovered by
their aid.

The Frue vanner will, as a rule, act well when the pulp is sufficiently
and consistently fine. It is an adaptation of the old simple apparatus
used in China and India for washing gold dust from river sand. The
original consisted of an endless band of strong cloth or closely woven
matting, run on two horizontal rollers placed about seven feet apart,
one being some inches lower than the other. The upper is caused to
revolve by means of a handle. The cloth is thus dragged upwards against
a small stream of water and sand fed to it by a second man, the first
man not only turning the handle but giving a lateral motion to the band
by means of a rope tied to one side.

    [Illustration: FIG. 24. FRUE VANNER.]

Chinamen were working these forerunners of the Frue vanner fifty years
ago in Australia, and getting fair returns.

The Frue vanner (Fig. 24) is an endless india-rubber band drawn over an
inclined table, to which a revolving and side motion is given by
ingenious mechanism, the pulp being automatically fed from the upper
end, and the concentrates collected in a trough containing water in
which the band is immersed in its passage under the table; the lighter
particles wash over the lower end. The only faults with the vanner
are--first, it is rather slow; and secondly, though so ingenious it is
just a little complicated in construction for the average non-scientific
operative.

Of pan concentrators there is an enormous selection, the principle in
most being similar--_i.e._, a revolving muller, which triturates the
sand, so freeing the tiny golden particles and admitting of their
contact with the mercury. The mistake with respect to most of these
machines is the attempt to grind and amalgamate in one operation. Even
when the stone under treatment contains no deleterious compounds the
simple action of grinding the hard siliceous particles has a bad effect
on the quicksilver, causing it to separate into small globules, which
either oxidising or becoming coated with the impurities contained in the
ore will not reunite, but wash away in the slimes and take with them a
percentage of the gold. As a grinder and concentrator, and in some cases
as an amalgamator, when used exclusively for either purpose, the Watson
and Denny pan (Fig. 25) is effective; but although successfully used at
one mine I know, the mode there adopted would, for reasons previously
given, be very wasteful in many other mines.

    [Illustration: FIG. 25. WATSON AND DENNY PAN.]

There is much misconception, even among men with some practical
knowledge, as to the proper function of these saving appliances; and
sometimes good machines are condemned because they fail to perform work
they were not intended for.

It cannot be too clearly realised that the correct order of procedure
for extracting the gold held in combination with base metals is--first,
reduction of the particles to a uniform gauge and careful concentration
only; next, the dissipation, usually by simple calcination, of
substances in the concentrates inimical to the thorough absorption of
the gold by the mercury; and lastly, the amalgamation of the gold and
mercury.

For general purposes, where the gangue has not been crushed too fine, I
think the Duncan pan will usually be found effective in saving the
concentrates. In theory it is an enlargement of the alluvial miner’s tin
dish, and the motion imparted to it is similar to the eccentric motion
of that simple separator.

The calcining may be effectively carried out in an ordinary
reverberatory furnace, the only skill required being to prevent over
“roasting” and so slagging the concentrates; or not sufficiently
calcining so as to remove all deleterious constituents; the subject,
however, is fully treated in Chapter VIII.

For amalgamating I prefer some form of settler to any further grinding
appliance, but I note also improvements in the rotary amalgamating
barrel, which, though slow, is, under favourable conditions, an
effective amalgamator. The introduction of steam under pressure into an
iron cylinder containing a charge of concentrates with mercury is said
to have produced good results, and I am quite prepared to believe such
would be the case, as we have long known that the application of steam
to ores in course of amalgamation facilitates the process considerably.

Some twenty-five years since I also was engaged on the construction of a
dry amalgamator in which sublimated mercury was passed from a retort
through the descending gangue in a vertical cylinder, the material
falling therefrom through an aperture into a revolving settler, the
object being to save water on mines in dry country. The model, about
quarter size, was completed, when my attention was called to an American
invention, in which the same result was stated to be attained more
effectively by blowing the mercury spray through the triturated material
by means of a steam jet. I had already encountered a difficulty, since
found so obstructive by experimentalists in the same direction, that
is, the getting of the mercury back into its liquid metallic form. This
difficulty can be largely obviated by my own device of using a very weak
solution of sulphuric acid (it can hardly be too weak) and adding a
small quantity of zinc to the mercury. It is perfectly marvellous how
some samples of mercury “sickened” or “floured” by bad treatment, may be
brought back to the bright, clean, easy flowing metal by a judicious use
of these inexpensive materials.

Thus it will probably be found practicable to crush dry and amalgamate
semi-dry by passing the material in the form of a thin pasty mass to a
settler, as in the old South American arrastra, and, by slowly stirring,
recover the mercury, and with it the bulk of the gold.

The following is from the _Australian Mining Standard_, and was headed
“Amalgamation Without Overflow”:

    “Recent experiments at the Ballarat School of Mines have proved
    that a deliverance from difficulties is at hand from an unexpected
    quarter. The despised Chilian mill and Wheeler pan, discarded at
    many mines, will solve the problem, but the keynote of success is
    amalgamation without overflow. Dispense with the overflow and the
    gold is saved.

    “Two typical mines--the Great Mercury Proprietary Gold Mine,
    of Kuaotunu, N.Z., the other, the Pambula, N.S.W.--have lately
    been conducting a series of experiments with the object of saving
    their fine gold in an economical manner. The last and best trials
    made by these companies were at the Ballarat School of Mines, where
    amalgamation without overflow was put to a crucial test, in each
    case with the gratifying result that ninety-six per cent. of the
    precious metal was secured. What this means to the Great Mercury
    Mine, for instance, can easily be imagined when it is understood
    that notwithstanding all the latest gold-saving adjuncts during the
    last six months 1260 tons of ore, worth £4. 17_s._ 10-2/3_d._ a ton,
    have been put through for a saving of £1 9_s._ 1-2/3_d._ only; or
    in other words over two-thirds of the gold has gone to waste (for
    the time being) in the tailings, and in the tailings at the present
    moment lie the dividends that should have cheered shareholders’
    hearts.

    “And now for the _modus operandi_, which, it must be remembered,
    is not hedged in by big royalties to any one, rights, patent or
    otherwise. The ore to be treated is first calcined, then put through
    a rock-breaker or stamper battery in a perfectly dry state. If the
    battery is used, ordinary precautions, of course, must be taken
    to prevent waste, or the dust becoming obnoxious to the workmen.
    The ore is then transferred to the Chilian mill and made to the
    consistency of porridge, the quicksilver being added. When the
    principal work of amalgamation is done (experience soon teaching the
    amount of grinding necessary), from the Chilian mill the paste (so
    to say) is passed to a Wheeler or any other good pan of a similar
    type, when the gold-saving operation is completed.”

This being an experiment in the same direction as my own, I tried it on
a small scale. I calcined some very troublesome ore till it was fairly
“sweet,” triturated it, and having reduced it with water to about the
consistency of invalid’s gruel, put it into a little berdan pan made
from a “camp oven,” which I had used for treating small quantities of
concentrates, and from time to time drove a spray of mercury, wherein a
small amount of zinc had been dissolved, into the pasty mass by means of
a steam jet, added about half an ounce of sulphuric acid and kept the
pan revolving for several hours. The result was an unusually successful
amalgamation and consequent extraction--over ninety per cent.

Steam--or to use the scientific term, hydro-thermal action--has played
such an important part in the deposition of metals that I cannot but
think that under educated intelligence it will prove a powerful agent in
their extraction. Twenty-five years ago I obtained some rather
remarkable results from simply boiling auriferous ferro-sulphides in
water. There is in this alone an interesting, useful, and profitable
field for investigation and experiment.

The most scientific and perfect mode of gold extraction (when the
conditions are favourable) is lixiviation by means of chlorine,
potassium cyanide, or other aurous solvent, for by this means as much as
98 per cent. of the gold contained in suitable ores can be converted
into its mineral salt, and being dissolved in water, re-deposited in
metallic form for smelting; but lode stuff containing much lime would
not be suitable for chlorination, or the presence of a considerable
proportion of such a metal as copper, particularly in metallic form,
would be fatal to success, while cyanide of potassium will also attack
metals other than gold, and hence discount the effect of that solvent.

The earlier practical applications of chlorine to gold extraction were
known as Mears’ and Plattner’s processes, and consisted in placing the
material to be operated on in vats with water, and introducing chlorine
gas at the bottom, the mixture being allowed to stand for a number of
hours, the minimum about twelve, the maximum forty-eight. The
chlorinated water was then drawn off containing the gold in solution
which was deposited as a brown powder by the addition of sulphate of
iron.

Great improvements on this slow and imperfect method have been made of
late years, among the earlier of which was that of Messrs. Newbery and
Vautin. They placed the pulp with water in a gas-tight revolving
cylinder, into which the chlorine was introduced, and atmospheric air to
a pressure of 60 lb. to the square inch was pumped in. The cylinder with
its contents was revolved for two hours, then the charge was withdrawn
and drained nearly dry by suction, the resultant liquid being slowly
filtered through broken charcoal on which the chloride crystals were
deposited, in appearance much like the bromo-chlorides of silver ore
seen on some of the black manganic oxides of the Barrier silver mines.
The charcoal, with its adhering chlorides, was conveyed to the
smelting-house and the gold smelted into bars of extremely pure metal.
Messrs. Newbery and Vautin claimed for their process decreased time for
the operation with increased efficiency.

At Mount Morgan, when I visited that mine in the eighties, they were
using what might be termed a composite adaptation process. Their
chlorination works, the largest in the world, were putting through 1500
tons per week. The ore as it came from the mine was fed automatically
into Krumm roller mills, and after being crushed and sifted to
regulation gauge was delivered into trucks and conveyed to the roasting
furnaces, and thence to cooling floors, from which it was conveyed to
the chlorinating shed. Here were long rows of revolving barrels, on the
Newbery-Vautin principle, but with this marked difference, that the
pressure in the barrel was obtained from an excess of the gas itself,
generated from a charge of chloride of lime and sulphuric acid. On
leaving the barrels the pulp ran into settling vats, somewhat on the
Plattner plan, and the clear liquid having been drained off was passed
through a charcoal filter, as adopted by Newbery and Vautin. The
manager, Mr. Wesley Hall, stated that the estimated cost per ton was not
more than 30_s._, and he expected shortly to reduce that when he began
making his own sulphuric acid. As he was obtaining over 4 oz. to the ton
the process was paying very well, but it will be seen that the price
would be prohibitive for poor ores unless they could be concentrated
before calcination.

The Pollok process is a newer, and stated to be a cheaper mode of
lixiviation by chlorine. It is the invention of Mr. J. H. Pollok, of
Glasgow University, and a strong Company was formed to work it. With him
the gas is produced by the admixture of bisulphate of sodium (instead of
sulphuric acid, which is a very costly chemical to transport) and
chloride of lime. Water is then pumped into a strong receptacle
containing the material for treatment and powerful hydraulic pressure is
applied. The effect is stated to be the rapid change of the metal into
its salt, which is dissolved in the water and afterwards treated with
sulphate of iron, and so made to resume its metallic form.

It appears, however, to me that there is no essential difference in the
pressure brought to bear for the quickening of the process. In each case
it is an air cushion, induced in the one process by the pumping in of
air to a cylinder partly filled with water, and in the other by pumping
in water to a cylinder partly filled with air.

The process of extracting gold from lode stuff and tailings by means of
cyanide of potassium is now largely used and may be thus briefly
described:--It is chiefly applied to tailings, that is, crushed ore that
has already passed over the amalgamating and blanket tables. The
tailings are placed in vats, and subjected to the action of solutions of
cyanide of potassium of varying strengths down to 0·2 per cent. These
dissolve the gold, which is leached from the tailings, passed through
boxes in which it is precipitated either by means of zinc shavings,
electricity, or other precipitant. The solution is made up to its former
strength and passed again through fresh tailings. When the tailings
contain a quantity of decomposed pyrites, partly oxidised, the acidity
caused by the freed sulphuric acid requires to be neutralised by an
alkali, caustic soda being usually employed.

When “cleaning up,” the cyanide solution in the zinc precipitating boxes
is replaced by clean water. After careful washing in the box, to cause
all pure gold and zinc to fall to the bottom, the zinc shavings are
taken out. The precipitates are then collected, and after calcination in
a special furnace for the purpose of oxidising the zinc, are smelted in
the usual manner.

The following description of an electrolytic method of gold deposition
from a cyanide solution was given by Mr. A. L. Eltonhead before the
Engineers’ Club of Philadelphia.

A description of the process is as follows:--“The ore is crushed to a
certain fineness, depending on the character of the gangue. It is then
placed in leaching vats, with false bottoms for filtration, similar to
other leaching plants. A solution of cyanide of potassium and other
chemicals of known percentage is run over the pulp and left to stand a
certain number of hours, depending on the amount of metal to be
extracted. It is then drained off and another charge of the same
solution is used, but of less strength, which is also drained. The pulp
is now washed with clean water, which leaches all the gold and silver
out, and leaves the tailings ready for discharge, either in cars or
sluiced away by water, if it is plentiful.

“The chemical reaction of cyanide of potassium with gold is as follows,
according to Elsner:--

    ₂Au + ₄KCy + O + H₂O = ₂KAuCy₂ + ₂KHO.

    That is, a double cyanide of gold and potassium is formed.

    “All filtered solutions and washings from the leaching vats
    are saved and passed through a precipitating ‘box’ of novel
    construction, which may consist either of glass, iron or wood,
    and be made in any shape, either oval, round, or rectangular--if
    the latter, it will be about 10 ft. long, 4 ft. wide and 1 ft.
    high--and is partitioned off lengthwise into five compartments.
    Under each partition, on the inside or bottom of the ‘box,’ grooves
    may be cut a quarter-to a half-inch deep, extending parallel with
    the partitions to serve as a reservoir for the amalgam, and give a
    rolling motion to the solution as it passes along and through the
    four compartments. The centre compartment is used to hold the lead
    or other suitable anode and electrolyte.

    “The anode is supported on a movable frame or bracket, so it
    may be moved either up or down as desired, it being worked by
    thumb-screws at each end.

    “The electrolyte may consist of saturated solutions of soluble
    alkaline metals and earths. The sides or partitions of each
    compartment dip into the mercury, which must cover the ‘box’ evenly
    on the bottom to the depth of about a half-inch.

    “Amalgamated copper strips or discs are placed in contact with
    the mercury and extended above it, to allow the gold and silver
    solution of cyanide to come in contact.

    “The electrodes are connected with the dynamo; the anode of
    lead being positive and the cathode of mercury being negative. The
    dynamo is started, and a current of high amperage and low voltage
    is generated, generally 100 to 125 amperes, and with sufficient
    pressure to decompose the electrolyte between the anode and the
    cathode.

    “As the gas is generated at the anode, a commotion is created
    in the liquid, which brings a fresh and saturated solution of
    electrolyte between the electrodes for electrolysis, and makes it
    continuous in its action.

    “The solution of double cyanide of gold, silver, and potassium,
    which has been drained from the leaching vats, is passed over the
    mercury in the precipitating ‘box’ when the decomposition of the
    electrolyte by the electric current is being accomplished, the
    gold and silver are set free and unite with the mercury, and are
    also deposited on the plates or discs of copper, forming amalgam,
    which is collected and made marketable by the well-known and tried
    methods. The above solution is regenerated with cyanide of potassium
    by the setting free of the metals in the passage over the ‘box.’

    “In using this solution again for a fresh charge of pulp, it is
    reinforced to the desired percentage, or strengthened with cyanide
    of potassium and other chemicals, and is always in good condition
    for continuing the operation of dissolving.

    “The potassium acting on the water of the solution creates
    nascent hydrogen and potassium hydrate; the nascent hydrogen sets
    free the metals (gold and silver), which are precipitated into the
    mercury and form amalgam, leaving hydrocyanic acid; this latter
    combines with the potassium hydrate of the former reaction, thus
    forming cyanide of potassium. There are other reactions for which I
    have not at present the chemical formulas.

    “As the solution passes over the mercury, the centre compartment
    of the ‘box’ is moved slowly longitudinally, which spreads the
    mercury, the solution is agitated and comes in perfect contact with
    the mercury, as well as the amalgamated plates or discs of copper,
    ensuring a perfect precipitation.

    “It is not always necessary to precipitate all the gold and
    silver from the solution, for it is used over and over again
    indefinitely; but when it is required, it can be done perfectly and
    cheaply in a very short time.

    “No solution leached from the pulp, containing cyanide of
    potassium, gold and silver, need be run to waste, which is in itself
    an enormous saving over the use of zinc shavings when handling large
    quantities of pulp and solution.

    “Some of the advantages the electro-chemical process has over
    other cyanide processes are: Its cleanliness, quickness of action,
    cheapness, and large saving of cyanide of potassium by regeneration;
    not wasting the solutions, larger recovery of the gold and silver
    from the solutions; the cost of recovery less; the loss of gold,
    silver, and cyanide of potassium reduced to a minimum; the use
    of caustic alkali in such quantity as may be desired to keep the
    cyanide solution from being destroyed by the acidity of the pulp,
    and also sometimes to give warmth, as a warm cyanide solution will
    dissolve gold and silver quicker than a cold one. These caustic
    alkalies do not interfere with or prevent the perfect precipitation
    of the metals. The bullion recovered in this process is very fine,
    while the zinc-precipitated bullion is only about 700 fine.

    “The gold and silver is dissolved, and then precipitated in
    one operation, which we know cannot be done in the ‘chlorination
    process’; besides, the cost of plant and treatment is much less in
    the above-described process.

    “The electro-chemical process, which I have hastily sketched
    will, I think, be the future cheap method of recovering fine or
    flour gold from our mines and waste tailings or ore dumps.

    “Without going into details of cost of treatment, I will state
    that with a plant of a capacity of handling 10,000 tons of pulp
    per month, the cost should not exceed 8_s._ per ton, but that may
    be cheapened by labour-saving devices. There being no expensive
    machinery, a plant could be very cheaply erected wherever necessary.”




    CHAPTER VIII

    CALCINATION OR ROASTING OF ORES


The object of calcining or roasting certain ores before treatment is to
dissipate the sulphur or sulphides of arsenic, antimony, lead, &c.,
which are inimical to treatment, whether by ordinary mercuric
amalgamation or lixiviation. The effect of the roasting is first to
sublimate and drive off as fumes the sulphur and a proportion of the
objectionable metals. What is left is either iron oxide, “gossan,” or
the oxides of the other metals. Even lead can thus be oxidised, but
requires more care as it melts nearly as readily as antimony and is much
less volatile. The oxides in the thoroughly roasted ore will not
amalgamate with mercury, and are not acted on by chlorine or cyanogen.

To effect the oxidation of sulphur, it is necessary not only to bring
every particle of sulphur into contact with the oxygen of the air, but
also to provide adequate heat to the particles sufficient to raise them
to the temperature that will induce oxidation. No appreciable effect
follows the mere contact of air with sulphur particles at atmospheric
temperature; but if the particles be raised to a temperature of 500°
Fahr., the sulphur is oxidised to the gaseous sulphur dioxide. The same
action effects the elimination of the arsenic and antimony associated
with gold and silver ores, as when heated to a certain constant
temperature these metals readily oxidise.

The science of calcination consists of the method by which the sulphide
ores, having been crushed to a proper degree of fineness, are raised to
a sufficient temperature and brought into intimate contact with
atmospheric air.

It will be obvious then that the most effective method of roasting will
be one that enables the particles to be thoroughly oxidised at the
lowest cost in fuel and in the most rapid manner.

The roasting processes in practical use may be divided into three
categories:

_First or Process A._--Roasting on a horizontal and stationary hearth,
the flame passing over a mass of ore resting on such hearth. In order to
expose the upper surface of the ore to contact with air the material is
turned over by manual labour. This furnace of the reverberatory type is
provided with side openings by which the turning over of the ore can be
manually effected, and the new ore can be charged and afterwards
withdrawn.

_Second or Process B._--Roasting in a revolving hearth placed at a
slightly inclined angle from the horizontal. The furnace is of
cylindrical form, and is internally lined with refractory material. It
has projections that cause the powdered ore to be lifted above the
flame, and, at a certain height, to fall through the flame and so be
rapidly raised to the temperature required to effect the oxidation of
the oxidisable minerals which it is desired to extract.

The rate, or speed, of revolution of this revolving furnace obviously
depends upon the character of the ore under treatment; it may vary from
two revolutions per minute down to one revolution in thirty minutes. Any
kind of fuel is available, but that of a gaseous character is stated to
be by far the most efficient.

Any ordinary cylinder of a length of 25 ft., and a diameter of 4 ft. 6
in., inclined 1 ft. 6 in. in its length, will calcine from 24 to 48 tons
per diem.

Another form of rotating furnace is one in which the axis is horizontal.
It is much shorter than the inclined type, and the feeding and removal
of the ore is effected by the opening of a retort lid door provided at
the side of the furnace. Openings provided at each end of the furnace
permit the passage of the flame through it, and the revolution of the
furnace turns over the powdered ore and brings it into more or less
sustained contact is continued sufficiently long to ensure the more or
less complete oxidation of the ore particles.

_Third or Process C._--In this process the powdered ore is allowed to
fall in a shower from a considerable height, through the centre of a
vertical shaft up which a flame ascends; the powdered ore in falling
through the flame is heated to an oxidising temperature, and the
sulphides are thus depleted of their sulphur and become oxides.

Another modification of this direct fall or shaft furnace is that in
which the fall of the ore is checked by cross-bars or inclined plates
placed across the shaft; this causes a longer oxidising exposure of the
ore particles.

When the sulphur contents of pyritous ores are sufficiently high, and
after the ore has been initially fired with auxiliary carbonaceous fuel,
it is unnecessary, in a properly designed roasting furnace, to add fuel
to the ore to enable the heat for oxidation to be obtained. The
oxidation or burning of the sulphur will provide all the heat necessary
to maintain the continuity of the process. The temperature necessary for
effecting the elimination of both sulphur and arsenic is not higher than
that equivalent to dull red heat; and provided that there is a
sufficient mass of ore maintained in the furnace, the potential heat
resulting from the oxidation of the sulphur will alone be adequate to
provide all that is necessary to effect the calcination.


    TYPES OF FURNACES OF THE DIFFERENT CLASSES THAT ARE IN ACTUAL USE.

    “A” OR Reverberatory Class.

The construction of this furnace has already been sufficiently
described. If the roasting is performed in a muffle chamber, the
arrangement employed by Messrs. Leach and Neal, Limited, of Derby, and
designed by Mr. B. H. Thwaite, C.E., can be advantageously employed in
this furnace, which is fired with gaseous fuel. The sensible heat of the
waste gases is utilised to heat the air employed for combustion; and by
a controllable arrangement of combustion, a flame of over 100 feet in
length is obtained, with the result that the furnace from end to end is
maintained at a uniform temperature. By this system, and with gaseous
fuel firing, a very considerable economy in fuel and in repairs to
furnace, and a superior roasting effect, have been obtained.

Where the ordinary reverberatory hearth is fired with solid coal from an
end grate, the temperature is at its maximum near the firing end, and
tails off at the extreme gas outlet end. The ores in this furnace should
therefore be fed in at the colder end of the hearth and be gradually
worked or “rabbled” forward to the firing end.

One disadvantage of the reverberatory furnace is the fact that it is
impossible to avoid the incursion of air during the manual rabbling
action, and this tends to cool the furnace.

The cost of roasting, to obtain the more or less complete oxidation, or
what is known in mining parlance as a “sweet roast” (because a perfectly
roasted ore is nearly odourless) varies considerably, the variation
depending of course upon the character of the ore and the cost of labour
and fuel.

There are several modifications of the reverberatory furnace in use,
designed mechanically to effect the rabbling. One of the most successful
is that known as the Horse-shoe furnace. In plan the hearth of the
furnace resembles a horse-shoe.

The stirring of the ore over the hearth is effected by means of
carriages fixed in the centre of the furnace and having laterally
projecting arms, carrying stirrers, that move along the hearth and turn
over the pulverised ore.

In operation, half the carriages are traversing the furnace, and half
are resting in the cooling space, so that a control over the temperature
of the stirrers is established.

This furnace is stated to be more economical in labour than other
mechanically stirred reverberatory furnaces, and there is also said to
be an economy in fuel.

Usually the mechanical stirring furnaces give trouble and should be
avoided, but the horse-shoe type possesses qualifications worthy of
consideration.


    “B.” The Revolving Cylinder Furnace.

Of these some of the best known to me are: The Howell-White, The
Brückner, The Thwaite-Denny, and the Molesworth.

The Brückner is a cylinder, turning on its horizontal axis and carried
by four rollers.

The batch of ore usually charged into the two charging hoppers weighs
about four tons. When the two charging doors are brought under the
hopper mouth, the contents of the hopper fall directly into the
cylinder.

The ends or throats of the furnace are reduced just sufficiently to
allow the flame evolved from a grated furnace to pass completely through
the cylinder.

A characteristic size for this Brückner furnace is one having a length
of 12 feet and a diameter of 6 feet. A furnace of this capacity will
have an inclusive weight (iron and brickwork) of 15 tons.

The time of operation, with the Brückner, will vary with the character
of the ore under treatment and the nature of the fuel employed. Four
hours is the minimum and twelve hours should be the maximum time of
operation.

By the addition of common salt with the batch of ore, such of its
constituents as are amenable to the action of chlorine are chlorinated
as well as freed from sulphur.

Where the ore contains any considerable quantity of silver which should
be saved, the addition of the salt is necessary as the silver is very
liable to become so oxidised in the process of roasting as to render its
after treatment almost impossible. I know a case in point where an
average of nearly five ounces of silver to the ton, at that time worth
30_s_., was lost owing to ignorance on this subject. Had the ore been
calcined with salt, NaCl, the bulk of this silver would have been
amalgamated and thus saved. It was the extraordinary fineness of the
gold saved by amalgamation as against my tests of the ore by fire assay
that put me on the track of a most indefensible loss.

_The Howell-White Furnace._--This furnace consists of a cast iron
revolving cylinder, averaging 25 feet in length and 4 ft. 4 in. in
diameter, which revolves on four friction rollers, resting on truck
wheels, rotated by ordinary gearing.

The power required for effecting the revolution should not exceed four
indicated horse-power.

The cylinder is internally lined with firebrick, projecting pieces
causing the powdered ore to be raised over the flame through which it
showers, and is thereby subjected to the influence of heat and to direct
contact oxidation.

The inclination of the cylinder, which is variable, promotes the gradual
descension of the ore from the higher to the lower end. It is fed into
the upper end, by a special form of feed hopper, and is discharged into
a pit at the lower end, from which the ore can be withdrawn at any time.

The gross weight of this furnace, which is, however, made in segments to
be afterwards bolted together, is some ninety to one hundred tons.

The furnace is fired with coal on a grated hearth, built at the lower
end; it is more economical both in fuel and in labour than an ordinary
reverberatory furnace.

_The Thwaite-Denny Revolving Furnace._--This new type of furnace, which
is fired with gaseous fuel, is stated to combine the advantages of the
Stetefeldt, the Howell-White, and the Brückner.

It is constructed as follows:--Three short cylinders, conical in shape
and of graduated dimensions, are superposed one over the other, their
ends terminating in two vertical shafts of brickwork, by which the three
cylinders are connected. The powdered ore is fed into the uppermost
cylinder and gravitates through the series. The highest cylinder is the
largest in diameter, the lowest the smallest.

The gas flame, burnt in a Bunsen arrangement, enters the smallest end of
the lowest cylinder and passes through it; then returns through the
intermediate cylinder above it, being directed by the brickwork
shaft--from one cylinder to the other--till finally the gases flow
through the topmost cylinder and enter into a dust depositing chamber.
The gases evolved increase as the flame flows through the series and the
ore is reduced by the expulsion of its sulphur, arsenic, &c., as it
descends from the top to the bottom. The top cylinder is made larger
than the one below it and the middle cylinder is made larger than the
lowest one in proportion to the increased bulk of gases and ore.

The powdered ore in descending through the cylinders is lifted up and
showers through the flame, falling in its descent a distance of over
1000 feet. By the time it reaches the bottom the ore is thoroughly
roasted.

Provision is made for the introduction of separate supplies of air and
gas into each cylinder; this enables the oxidising treatment to be
controlled exactly as desired so as to effect the best results with all
kinds of ore. Each cylinder is driven from its own independent gearing,
and the speed of each cylinder can be varied at will.

The output of this type of furnace, the operations of which appear to be
more controllable than those of similar appliances, depends, of course,
upon the nature of the ore, but may be considered to range within the
limits of twelve to fifty tons in twenty-four hours, and the cost of
roasting will vary from 2_s._ 6_d._ to 4_s._ per ton, depending upon the
quality of ore and of fuel.

The gaseous fuel generating system permits not only the absolute control
over the temperature in the furnace, but the use of the commonest kinds
of coal, and even charcoal is available.

The power required to drive the Thwaite-Denny furnace is four indicated
horse-power.

_The Molesworth Furnace_ also is a revolving cylindrical appliance,
which, to say the least of it, is in many respects novel and ingenious.
It consists of a slightly cone-shaped, cast-iron cylinder about fourteen
feet long, the outlet end being the larger to allow for the expansion of
the gases. Internal studs are so arranged as to keep the ore agitated;
and spiral flanges convey it to the outlet end continually, shooting it
across the cylinder. The cylinder is encased in a brick furnace. The
firing is provided from _outside_, the inventor maintaining that the
products of combustion are inimical to rapid oxidisation, to specially
promote which he introduces an excess of oxygen produced in a small
retort set in the roof of the furnace and fed from time to time with
small quantities of nitrate of soda and sulphuric acid. Ores containing
much sulphur virtually calcine themselves. I have seen this appliance
doing good work. The difficulties appeared to be principally mechanical.

There are other furnaces which work with outside heat, but I have not
seen them in action.


    “C.”--Shaft Type of Furnace.

In one form of this furnace, instead of allowing the ore to descend in a
direct clear fall the descent is impeded by inclined planes placed at
different levels in the height of the shaft, the ore descending from one
plane to the other.

_The Stetefeldt Shaft Furnace._--Although very expensive in first cost,
has many advantages. No motive power is required and the structure of
the furnace is of a durable character. Its disadvantages are:--Want
of control, and the occasionally imperfect character of the roasting
originating therefrom.

Three sizes of Stetefeldt’s furnaces are constructed:

    The largest will roast from 40 to 80 tons per diem.

    The intermediate     ”     ”    20  ” 40     ”     ”      ”

    The smallest         ”     ”    10  ” 20     ”     ”      ”

A good furnace should bring down the sulphur contents even of
concentrates so as to be innocuous to mercuric amalgamation. The sulphur
left in the ore should never be allowed to exceed two per cent.

A forty per cent. pyritous or other sulphide ore should be roasted in a
revolving furnace in thirty to forty minutes, and without any auxiliary
fuel.

For ordinary purposes a 40-foot chimney is adequate for furnace work;
such a chimney four feet square inside at the base, tapering to 2’ 6” at
the summit, will require 12,000 red bricks, and 1500 fire-bricks for an
internal lining to a height of 12 feet from the base of the chimney
shaft.

When second-hand Lancashire or Cornish boiler flues are available, they
make admirable and inexpensive chimneys. The advantage of wrought-iron
or steel chimneys lies in the convenience of removal and erection. They
should be made in sections of 20 feet long, three steel wire guy-ropes
attached to a ring, riveted to a ring two-thirds of the height of the
chimney, and attached to holdfasts driven into the ground; tightening
couplings should be provided for each wire.

Flue dust depositing chambers should be built in the line of the flues
between the furnace and the chimney; they consist simply of carefully
built brick chambers, with openings to enable workmen to enter and
rapidly clear away the deposited matters. The chambers, three or four
times the cross sectional area of the chimney flue, and ten to twenty
feet long, can be built of brickwork, set in cement; the walls are
provided with a cavity, filled with sand or Portland cement, so that
there will be no danger of the incursion of air. In all furnace work the
greatest possible precautions should be taken to prevent the least
cracking of either joints or bricks. It is surprising how much the
inadequate draft of a good chimney is due to cracks or orifices in the
flues; and therefore a competent furnace-man should see to it that his
flues are thoroughly sound, and free from openings through which the air
can enter.[2]

    [2] For full details of the most recent improvements in the
    cyanide process and in other methods of extraction, the reader is
    referred to Dr. T. K. Rose’s “Metallurgy of Gold,” third edition.




    CHAPTER IX

    MOTOR POWER AND ITS TRANSMISSION


It is unnecessary to describe the methods by which power for mining
purposes has been obtained--that is, up to within the last five
years--beyond a general statement, that when water power has been
available in the immediate locality of the mine, this cheap natural
source of power has been called upon to do duty. Steam has been the
alternative agent of power production applied in many different ways,
but labouring under as many disadvantages, chief of which are lack of
water, scarcity of fuel and cost of transit of machinery. Sometimes
condensing steam-engines have been employed. For the generation of steam
the semi-portable and semi-tubular have been the type of boiler that has
most usually been brought into service. Needless to say, when highly
mineralised mine water only is available the adoption of this class of
boiler is attended with anything but satisfactory results.

Recently, however, there is strong evidence that where steam is the
power agent to be employed the water-tube type of boiler is likely to be
employed, and to the exclusion of all other forms of apparatus for the
generation of steam. The advantages of this type, particularly the
tubulous form (or a small water tube), made as it is in sections, offers
unrivalled facilities for transport service. The heaviest parts need not
exceed 3 cwt. in weight, and require neither heavy nor yet expensive
brickwork foundations.


    WATERLESS POWER.

The difficulties in finding water to drive a steam plant are often of
such a serious character as to involve the abandonment of many payable
mines; therefore, a motive power that does not require the aqueous agent
will be a welcome boon.

It will be a source of gratification to many a gold-claim holder to
know that practical science has enabled motive power to be produced
without the necessity of water, except a certain very small quantity,
which once supplied will not require to be renewed, unless to compensate
for the loss due to atmospheric evaporation.

Any carbonaceous fuel, such as, say, lignite, coal, or charcoal, can be
employed. The latter can be easily produced by the method described in
the Chapter on “Rules of Thumb,” or by building a kiln by piling
together a number of trunks of trees, or fairly large-sized branches,
cut so that they can be built up in a compact form. The pile, after
being covered with earth, is then lighted from the base, and if there
are no inlets for the air except the limited proportion required for the
smouldering fire at the base, the whole of the timber will be gradually
carbonised to charcoal of good quality, which is available for the
waterless power plant.

The waterless power plant consists of two divisions: First, a gas
generating plant; secondly, an internal combustion or gas engine in
which the gas is burnt, producing by thermo-dynamic action the motive
power required. The system known as the Thwaite Power Gas System is not
only practically independent of the use of water, but its efficiency in
converting fuel heat into work is so high that no existing steam plant
will be able to compete with it.

The weight of raw timber, afterwards to be converted into charcoal, that
will be required to produce an effective horse-power for one hour equals
7 lb.

    If coal is the fuel 1⅓ lb. per E. H. P. for one hour’s run.
    If lignite     ”    2½          ”            ”      ”

The plant is simple to work, and as no steam boiler is required the
danger of explosions is removed. No expensive chimney is necessary for
the waterless power plant.

Where petroleum oil can be cheaply obtained, say for twopence per
gallon, one of the Otto Cycle Oil Engines, for powers up to 20 indicated
horse-power, can be advantageously employed.

These engines have the advantage of being a self-contained power,
requiring neither chimney nor steam boiler, and may be said to be a
waterless power. The objection is the necessity to rely upon oil as
fuel, and the dangers attending the storage of oil. A good oil engine
should not require to use more than a pint of refined petroleum per
indicated horse-power working for one hour.

Fortunately for the mining industry electricity, that magic and
mysterious agency, has come to its assistance, in permitting motive
power to be transmitted over distances of even as much as 100 miles with
comparatively little loss of the original power energy.

Given, that on a coal or lignite field, or at a waterfall, 100
horse-power is developed by the combustion of fuel or by the fall of
water driving a turbine, this power can be electrically transmitted to a
mine or GROUP OF MINES, say 100 miles away, with only a loss of some 30
horse-power. For twenty miles the loss on transmission should not exceed
15 horse-power, so that 70 and 85 horse-power respectively are available
at the mines. No other system offers such remarkable efficiencies of
power transmission. The new Multiphase Alternating Electric Generating
and Power Transmission System is indeed so perfect as to leave
practically no margin for improvement.

The multiphase electric motor can be directly applied to the stamp
battery and ore-breaker driving-shaft and to the shaft of the
amalgamating pans.


    Approximate Power Required to Drive the Machinery of a Mine.

    Rock breaker                      10     effective horse-power
    Amalgamating pan                   5            ”         ”
    Grinding pan                       6            ”         ”
    Single stamp of 750 lb. dropping
       90 times per minute             1·25         ”         ”
    Settlers                           4            ”         ”
    Ordinary hoisting lift            20            ”         ”

    Allow 10 per cent. in addition for overcoming friction.

Besides this electrical distributing power, which should not cost more
than three farthings per effective horse-power per hour, the electrical
energy can be employed for lighting the drives and the shafts of the
mine. The modern electrical mine lamps leave little to be desired. Also
it is anticipated that once the few existing difficulties have been
surmounted electric drilling will supplant all other methods.

Electric power can be employed for pumping, for shot firing, for
hauling, and for innumerable purposes in a mine.

Electricity lends itself most advantageously to so many and varied
processes, even in accelerating the influence of cyanide solutions on
gold, and in effecting the magnetic influence on metallic particles in
separating processes; while applied to haulage purposes, either on
aërial lines (Fig. 26) or on tram or railroads, it is an immediate and
striking success.

    [Illustration: FIG. 26. ELECTRICAL AËRIAL TRAMWAY.]

It is anticipated that in the near future the mines on the Rand, South
Africa, will be electrically driven from a coalfield generating station
located on the coalfields some thirty miles from Johannesburg. Such a
plant made up of small multiples of highly efficient machines will
enable mine-owners to obtain a reliable power to any extent at immediate
command and at a reasonable charge in proportion to the power used. This
wholesale supply of power will be a godsend to a new field, enabling the
opening up to be greatly expedited; and no climatic difficulties, such
as dry seasons, or floods, need interfere with the regular running of
the machinery. The same system of power-generation at a central station
is to be applied to supply power to the mines of Western Australia.




    CHAPTER X

    COMPANY FORMATION AND OPERATIONS


All the world over, the operation of winning from the soil and rendering
marketable the many valuable ores and mine products which abound is
daily becoming more and more a scientific business which cannot be too
carefully entered into or too skilfully conducted. The days of the dolly
and windlass, of the puddler, cradle, and tin dish, are rapidly
receding; and mining, either in lode or alluvial working, is being more
generally recognised as one of the exact sciences. In the past, mining
has been carried on in a very haphazard fashion, to which much of its
non-success may be attributed.

But the dawn of better days has arrived, and with the advent of schools
of mines and technical colleges there will in future be less excuse for
ignorance in this most important industry.

This chapter will be devoted to Company formation and working, in which
mistakes leading to very serious consequences daily occur.

It is not necessary to go deeply into the question why, in the mining
industry more than any other, it should be deemed desirable as a general
rule to carry on operations by means of public Companies, but, as a
matter of fact, few names can be mentioned of men who mine extensively
single handed. Yet, risky as it is, mining is hardly more so than, say,
pastoral pursuits, in which private individuals risk, and often lose or
make, enormous sums of money.

In floating Mining Companies the first mistake usually made is not
providing sufficient working capital for meeting all necessary expenses
until permanent profits are realisable. This neglect has caused the
sacrifice of many good properties. In England, the Companies are often
floated fully paid up, but the same initial error of providing too
little money for the equipment and effective working of the mine is
usually fallen into.

Again, far too many Companies are floated on the report of plausible,
ignorant individuals posing as mining experts. These men acquire a few
geological and mining phrases, and by more or less skilfully
interlarding these with statements of large lodes and big returns they
supply reports seductive enough to float the most worthless properties
and cause the waste of thousands of pounds. But the trouble does not end
here.

When the Company is to be formed, some lawyer, competent or otherwise,
is instructed to prepare articles of association, rules, &c., which,
three times out of four, is accomplished by a liberal employment of
scissors and paste. Such rules may or may not be suited to the
requirements of the organisation. Generally no one troubles much about
the matter, though on these rules depends the future efficient working
of the Company, and sometimes its very existence.

Then Directors have to be appointed, and these are seldom selected
because of any special knowledge of mining they may possess, but as a
rule simply because they are large shareholders or prominent men whose
names look well in a prospectus. These gentlemen forthwith engage a
Secretary, usually on the grounds that he is the person who has tendered
lowest, to provide office accommodation and keep the accounts; and not
from any particular knowledge he has of the true requirements of the
position.

The way in which some Directors contrive to spend their shareholders’
money is humorously commented on by a Westralian paper which describes a
great machinery consignment landed in the neighbourhood of the Boulder
Kalgoorlie.

    “It would seem as if the purchaser had been let loose blindfold
    in a prehistoric material founder’s old iron yard, and having bought
    up the whole stock, had shipped it off. The feature of the entire
    antediluvian show is the liberal allowance of material devoted
    to destruction. Massive kibbles, such as were used in coal mines
    half a century ago, are arranged alongside a winding engine,
    built in the middle of the century, and evidently designed for
    hauling the kibbles from a depth of 1000 feet. Nothing less than
    horse power will stir the trucks for underground use, and their
    design is distinctly of the antique type. The engine is built to
    correspond--of a kind that might have served to raise into position
    the pillars of Baalbec, and the mass of metal in it fairly raises
    a blush to the iron cheek of frailer modern constructions. The one
    grand use to which this monster could be put would be to employ it
    as a kedge for the Australian continent in the event of it dragging
    its present anchors and drifting down south, but as modern mining
    machinery the whole consignment is worth no more than its value as
    scrap-iron, which in its present position is a fraction or two less
    than nothing.”

Next a man to manage the mine has to be obtained, and some one is placed
in charge, of whose capabilities the Directors have no direct knowledge.
Being profoundly ignorant of practical mining they are incompetent to
examine him as to his qualifications, or to check his mode of working,
so as to ascertain whether he is acting rightly or not. All they have to
rely on are some certificates often too carelessly given and too easily
obtained. Finally, quite a large proportion of the allottees of shares
have merely applied for them with the intention of selling out on the
first opportunity at a premium, hence they have no special interest in
the actual working of the mine.

Now let us look at the prospects of the Association thus formed. The
legal Manager or Secretary, often a young and inexperienced man, knows
little more than how to keep an ordinary set of books, and not always
that. He is quite ignorant of the actual requirements of the mine, or
what is a fair price to pay for labour, appliances, or material. He
cannot check the expenditure of the Mining Manager, who may be a rogue
or a fool or both, for we have had samples of all sorts to our sorrow.
The Directors are in like case. Even where the information is honestly
supplied, they cannot judge whether the work is being properly carried
out or is costing a fair price, and the Mining Manager is left to his
own devices, with no one to check him nor any with whom he can consult
in specially difficult cases. Thus matters drift to the almost certain
conclusion of voluntary or compulsory winding up; and so many a good
property is ruined, and promising mines, which have never had a
reasonable trial, are condemned as worthless. But let us ask, would any
other business, even such as are less subject to unforeseen vicissitudes
than mining, succeed under similar circumstances?

It is now very generally agreed that to the profitable development of
mining, new countries at all events must look mainly for prosperity
while other industries are growing. Therefore, we cannot too seriously
consider how we may soonest make our mines successful.

What is the remedy for the unsatisfactory state of affairs we have
experienced? The answer is a more practical system of working from the
inception. Although it may evoke some difference of opinion I consider
it both justifiable and desirable that the State should take some
oversight of mining matters, at least in the case of public Companies.
It would be a salutary rule that the promoters of any mining undertaking
should, before they are allowed to place it on the market, obtain and
pay for the services of a competent Government Mining Inspector, who
need not necessarily be a Government officer, but might, like licensed
surveyors, be granted a certificate of competency either by a School of
Mines or by some qualified Board of Examiners. The certificate of such
Inspector that the property was as represented should be given before
the prospectus was issued. It is arguable whether even further oversight
might not properly be taken by the State, and the report of a qualified
officer be compulsory that the property was reasonably worth the value
placed upon it in the prospectus.

Probably it will be contended that such restrictions would be an undue
interference with private rights, and the old aphorism about a fool and
his folly will be quoted. There are doubtless fools so infatuated that
if they were brayed in a ten hundred-weight stamp battery the
foolishness that had not departed from them would give a highly payable
percentage to the ton. Yet the State in other matters tries by numerous
laws to protect such from their folly. A man may not sell a load of wood
without the certificate from a licensed weighbridge nor a loaf of bread
without, if required, having to prove its weight; and we send those to
gaol who practice on the credulity and cupidity of fools by means of the
“confidence trick.” Why not, therefore, where interests which may be
said to be national are involved, endeavour to ensure fair dealing?

Then with regard to the men who are to manage our mines, seeing that a
man may not become captain or mate of a river steamboat without some
certificate of competency, nor drive her engines before he has passed an
examination to prove his fitness, surely it is not too much to say that
the mine manager or engineer, to whose care are often confided the lives
of hundreds of men, and the expenditure of thousands of pounds, should
be required to obtain a recognised diploma to prove his qualifications.
The examinations might be made comparatively easy at first, but
afterwards, when by the establishment of Schools and Mines the
facilities have been afforded for men to thoroughly qualify, the
standard should be raised; and after a date to be fixed no man should be
permitted to assume the charge of a mine or become one of its officers
without a proper certificate of competency from some recognised School
of Mines or Technical College. The effect of such a regulation would in
a few years produce most beneficial results.

In New Zealand, whose “progressive” legislature I do not generally
commend, they have, in the matter of mine management, at all events,
taken a step in the right direction. There a mine manager, before he
obtains his certificate, must have served at least two years
underground, and has to pass through a severe examination, lasting for
days, in all subjects relating to mining and machinery connected with
mining. In addition, he must prove his capacity by making an underground
survey, and then plotting his work. The examination is a stiff one, as
may be judged from the fact that between 1886 and 1891, only 27
candidates passed. Then the conditions were made easier, and from that
date to 1895, 19 passed. Of the 46 students who gained first-class
honours, 30 have left for South Africa or Australia, in both of which
countries New Zealand certificated men are held in high estimation.

The result of the establishment of our own School of Mines (Plate V.)
has been to raise the standard of the mine officer, whether manager,
assayer, engineer, or “underground boss,” and our graduates have small
difficulty in obtaining positions both in the states of the Commonwealth
and in South Africa. The building alone cost nearly £40,000, of which
£15,000 was donated by the Hon. George Brookman, a successful mining
man. The mining and metallurgical courses extend over a period of four
years. There are also facilities for students to gain higher
qualifications, viz., the Fellowship in Mining, Metallurgy, Mechanical
Engineering, or Electrical Engineering. The School works in conjunction
with the Adelaide University, each institution teaching the subjects for
which it is specially qualified.

But returning to the formation of the Company, care should be taken in
appointing Directors that at least one member of the Board is selected
on account of his special technical knowledge of mining, and others for
their special business capacity. The ornamental men with high-sounding
names should not be required in legitimate ventures. Also, it is most
important that the business Manager or Secretary should be a thoroughly
qualified man, who by experience has learned what are the requirements
of a mine doing a certain amount of work, so that a proper check may be
kept on the expenses. The more Companies such a Secretary has in hand
the better, as one qualified man can supervise a large staff of clerks,
who would themselves be qualifying for similar work, and gaining a
useful and varied experience of mining business. An office of this
description having charge of a large number of mines is, in its way, a
technical school, and lads trained therein would be in demand as mine
pursers, a very responsible and necessary officer in a big mine.

    [Illustration: PLATE V.--SOUTH AUSTRALIAN SCHOOL OF MINES AND
    INDUSTRIES _To face p. 118_]

With respect to the men to whom the actual mining and treatment of ores
and machinery is committed the greatest mistakes of the past have been
that too much has been required from one man. The Mining Manager has
been expected to be a miner, metallurgist, engineer, and business man,
a combination not to be found probably in one man in a thousand. Such
Admirable Crichtons are rare in any profession or business, and that of
mining is no exception. Men who profess too much are to be distrusted.
Your best men are they who concentrate their energies and intellects
in special directions. The Mining Manager should, if possible, be
chosen from men holding certificates of competency from some technical
mining school and, of course, should, in addition, have some practical
experience, not necessarily as Head Manager. He should understand
practical mine surveying and calculation of quantities, be able to dial
and plot out his workings, and prepare an intelligible plan thereof for
the use of the Directors, and should understand sufficient of physics,
particularly pneumatics and hydraulics, to ensure thoroughly efficient
pumping operations without loss of power from unnecessarily heavy
appliances. Any other scientific knowledge applicable to his business
which he may have acquired will tell in his favour, but he must, above
all things, be a thoroughly practical man. Such men will in time be more
readily procurable, as students who have passed through the various
Schools of Mines will be sent to learn their business practically at the
mines just as we now, having given a lad a course of naval instruction,
send him to sea to learn the practical part of his life’s work.

But, of course, more is wanted on a mine than a man who can direct the
sinking of shafts, driving of levels, and stoping of the lode. Much loss
and disappointment have resulted in the past from unsuitable,
ineffective, or badly designed and erected machinery, whether for
working the mine or treating the ores. To obviate this defect a
first-class mining engineer is required.

Then, also, day by day we are more surely learning that mining in all
its branches is a science, and that the treatment of ores and extraction
of the metals is daily becoming more and more the work of the laboratory
rather than of the rule-of-thumb procedure of the past. Every mine,
whether it be of gold, silver, tin, copper, or other metal, requires the
supervision of a thoroughly qualified metallurgist and chemist, and one
who is conversant with the newest processes for the extraction of the
metals from their ores and matrices.

It has then been stated that to ensure effective working each mine
requires, in addition to competent directors, a business-manager,
mining-manager, and assistants, engineer, chemist, and metallurgist,
with assistant assayers, &c., all highly qualified men. But it will be
asked, how are many struggling mines in sparsely populated countries to
obtain the services of all these eminent scientists? The reply is by
co-operation. One of the most ruinous mistakes of the past has been that
each little mining venture has started on an independent course, with
different management, separate machinery, &c. Can it then be wondered at
that our gold-mining is not always successful?

Under a co-operative system all that each individual mine would require
would be a qualified, practical miner capable of opening and securing
the ground in a miner-like manner, and a good working engineer; and in
gold-mining, where the gold is free in its matrix, a professional
amalgamator, or lixiviator. For the rest, half a dozen or more mines may
collectively retain the services of a mine manager of high attainments
as general inspector and superintendent, and the same system could be
adopted with respect to an advising metallurgist and an engineer. For
gold, as indeed for other metals, a central extracting works, where the
ores could be scientifically treated in quantity, might be erected at
joint cost, or might easily be arranged for as a separate business.

A very fruitful cause of failure is the fatuous tendency of directors
and mine managers to adopt new processes and inventions simply because
they are new. As an inventor in a small way myself, and one who is
always on the watch for improved methods, I do not wish to discourage
intelligent progress; but the greatest care should be exercised by those
having the control of the money of shareholders in mining properties
before adopting any new machinery or process.

We have seen, and unfortunately shall see, many a promising mining
company brought to grief by this popular error. The directors of mining
companies might, to use an American saying, “paste this in their hats”
as a useful and safe aphorism. “Let Others Do the Experimenting; We Are
Willing to Pay Only For Proved Improvements.” I can cordially endorse
every word of the following extracts from Messrs. McDermott and
Duffield’s admirable little work, “Losses in Gold Amalgamation.”

    “Some directors of mining companies are naturally inclined to
    listen to the specious promises of inventors of novel processes and
    new machinery, forgetting their own personal disadvantage in any
    argument on such matters, and assuming a confidence in the logic of
    their own conclusions, while they ignore the fruitful experience of
    thousands of practical men who are engaged in the mining business.
    The repeated failures of directors in sending out new machinery to
    their mines ought by this time to be a sufficient warning against
    increasing risks that are at once natural and unavoidable, and
    to deter them from plunging their shareholders into experiments
    which, in ninety-nine cases out of a hundred, result in nothing but
    excessive and needless expense.

    “It is certain that new machines and new processes are, and will
    be, given attention by mining men in proportion to their probable
    merits; but the proper place for experiments is in a mill already
    as successful as under known processes it can be made. In a new
    enterprise, even when the expense of an experiment is undertaken by
    the inventor, the loss to the mine-owner in case of failure must be
    very great, both in time and general running expenses. Directors
    should not believe that a willingness to risk cash in proving an
    invention is necessarily any proof of value of the same; it is only
    a measure of the faith of the inventor, which is hardly a safe
    standard to risk shareholders’ money by.

    “The variety of modifications in approved processes ought at
    least to suggest the desirability of exhausting the known, before
    drawing on the unknown and purely speculative. It should also be
    borne in mind that what might appear at first sight to be new
    processes, and even new machinery, are, in fact, often nothing but
    old contrivances and plausible theories long ago exploded among
    practical men.

    “Many mining companies have been ruined, without any reference
    to their mines, through men deciding on the reasonableness of new
    process and machinery who have no knowledge of the business in
    hand. It is assumed often, that if an inventor or manufacturer of
    new machinery will agree to guarantee success, or take no pay if
    not successful, the company takes no risk. In actual fact a whole
    year is wasted in most cases, failure spoils the reputation of
    the company, running expenses have continued, and further working
    capital cannot be raised, because all concerned have lost confidence
    by the failure to obtain returns promised. All this in addition
    to the regular, unavoidable risks of mining itself, which may, at
    any moment during the year lost, call for increased expenses and
    increased faith in ultimate success. To the mining man who makes
    money by the business, the natural risks of mining is all he will
    take; it is sufficient; and when he invests more money in machinery
    he takes good care that he takes no chances of either failure or
    delay.

    “The following are rules which no mining company or individual
    mine-owner can afford to neglect.

    “(1) The risk should be confined to mining. No body of directors
    is justified in taking a shareholder’s money and investing it in new
    processes or machinery when the subscription was simply for a mining
    venture. Directors are invariably incapable of deciding whether a
    so-called improvement in machinery or process is really so or not,
    and the reasonable course is to follow established precedents.

    “(2) The risk of selecting an incompetent manager should be
    reduced to minimum by taking a man with a successful record in
    the particular work to be done. The manager selected should be
    prohibited, as much as the directors, from experimenting with new
    methods or machinery. A really experienced man will require no check
    in this direction, as he will not risk ruining his reputation.

    “(3) The only time for a company to experiment is when the
    mine is paying well by the usual methods, and the treasury is in a
    condition to speculate a little in possible improvements without
    jeopardising regular returns.”

Probably this is the best place to insert another word of warning to
directors who are not mining specialists, and also to investors in gold
mining shares. Assays of auriferous lode material should always be
checked by the results of trials on large quantities. The reason is
obvious. First, the prospector or company promoter is not in the least
likely to pick the worst piece of stone in the heap for assay; and,
secondly, even should the sample be selected with the sole object of
getting a fair result, no living man can judge the value of a gold lode
by the result of treatment of an ounce of stone. So when it is reported
that a sample of rock from the Golden Mint Mine, Golconda, assays at the
rate of 2,546 oz. 13 dwt. and 21 grs. to the ton, and that there are
thousands of tons of similar stone in sight, the statement should be
received with due caution. The assay is doubtless correct, but the
deductions therefrom are most misleading.

A few words of advice also to directors of mine-purchasing companies and
syndicates, of which there are now so many in existence, may probably be
found of value. It is not good policy as a general rule to buy entirely
undeveloped properties, unless such have been inspected by your own man,
who is both competent and trustworthy, and indeed who should have an
interest in the profits. Large areas, although so popular in England, do
not compensate for large bodies of payable ore; the most remunerative
mine is generally one of comparatively small area, but containing a
large lode formation of payable, but often low grade, ore.

It is worse still, of course, to buy a practically worked out mine,
though this too is sometimes done. It must be remembered that mining,
though often so profitable, is nevertheless a destructive industry, thus
differing from agriculture, which is productive, and manufactures, which
are constructive. Every ton of stone broken and treated from even the
best gold mine in the world makes that mine the poorer by one ton of
valuable material; thus, to buy a mining property on its past reputation
for productiveness is, as a rule, questionable policy, unless you know
there is sufficient good ore in sight to cover the purchase cost and
leave a profit.

The point may be put thus: Human industry is (1) Productive, (2)
Constructive, and (3) Destructive.

(1) Productive.--Intelligent culture of the soil, including the
depasturage of profitable animals. This is the oldest.

(2) Constructive.--The manufacture of raw products, animal, vegetable,
and mineral, into articles of a necessary or æsthetic character.

(3) Destructive.--Mining, in all its forms, because the natural stores
of valuable minerals and metals won and used are not replaceable.

One of the greatest causes of non-success of gold mining ventures,
particularly when worked by public companies, is the lack of actual
personal supervision, and hence, among other troubles, is that
ultra-objectionable one--gold stealing from the mills, or, in alluvial
mining, from the tail races. As to the former, the following appeared in
1893 in the London _Mining Journal_, and is, I think, worthy of the
close consideration of mine directors in all parts of the world:--

    “No one that has not experienced the evil of gold thieving
    from reduction mills can have any idea of the pernicious element
    it is, and the difficulty, once that it has got ‘well hold,’ of
    rooting it out. It permeates every class of society in the district
    connected with the industry, and managers, amalgamators, assayers,
    accountants, aye, even bank officials, are ‘all on the job’ to ‘get
    a bit’ while there is an opportunity. To exterminate the hateful
    monster requires on the part of the mine proprietors combined, stern
    and drastic measures undertaken under the personal supervision of
    one or more of their directors, and in many instances necessitating
    the removal of the whole of the official staff.”

The writer narrates how about twenty-five years ago he was led to
suspect that in an Australian mine running forty head of stamps, in
which he held a controlling interest, the owners were being defrauded of
about a fourth of the gold really contained in the ore, and the
successful steps taken to check the robbery.

    “We first of all dispensed with the services of the general
    manager, and then issued the following instructions to the mine and
    mill managers, I remaining at the mine to see them carried out until
    I substituted a practical local man as agent, who afterwards carried
    on the work most efficiently:--

    “(_a_) Both of these officials to keep separate books and
    accounts; in other words, to be distinct departments.

    “(_b_) The ore formerly was all thrown together and put through
    the mill. I subdivided it into four classes, A, B, C, and D,
    representing deep levels north and upper levels north, deep levels
    south and upper levels south, and allotted to each class ten heads
    of stamps at the mill.

    “(_c_) The mine manager to try three prospects, forenoon and
    afternoon of each day, from the dumps of each of the four classes
    and record in a book to be kept for that purpose the estimated mill
    yield of each one.

    “(_d_) The mill manager was required to do the same at the mill
    and keep his record.

    “(_e_) There were four underground bosses in each shift, twelve
    in all. I had a book fixed at the top of the shaft in which I
    required each of these men, at the expiry of every shift, to record
    any change in the faces of the quartz and particularly in regard to
    quality.

    “(_f_) Having divided the ore into four classes I instructed the
    amalgamators, of which there were two in each shift, six in all,
    that I required the amalgam from each to be kept separate, with the
    object of ascertaining what each part of the mine produced.

    “(_g_) I procured padlocks for the covering boards of the
    mercury tables and gave the keys to the amalgamators with
    instructions that they were not to hand them over to any one except
    the exchange shift without my written authority, and instructed them
    that they should clean down the plates every three hours, and after
    cleaning down the amalgam, buckets to be placed in the cleaning
    room, which I instructed to be kept locked and the key in charge of
    a watchman night and day.

    “(_h_) The whole of the amalgam taken from the plates during each
    twenty-four hours to be cleaned and squeezed by the two amalgamators
    on duty every forenoon at nine o’clock in the presence of the mill
    manager, who should weigh each lot and enter it in a book to be kept
    for the purpose, and the entry to be signed by the mill manager and
    both amalgamators as witnesses.

    “(_i_) Every alternate Friday the mortars (boxes) to be cleaned
    out; the work to be commenced punctually at eight A.M. by the six
    amalgamators in the presence of the mill manager, assisted by the
    three amalgam cleaning room watchmen and the four battery feeders
    on duty, prohibiting any of them from leaving until the cleaning up
    was finished, and the amalgam cleaned, squeezed and weighed, and the
    amount entered by the mill manager in the record book and attested
    by the amalgamators.

    “I think the intelligent readers (particularly those with
    a knowledge of the business) will see the drift of the above
    regulations, viz., for there to be any peculation the whole of the
    battery staff--fourteen in all--would have to participate in it,
    and the number was too many to keep a secret. Formerly the amalgam
    cleaning room was sacred to the mill manager, and on announcing
    to that official the new instructions he at once tendered his
    resignation in a tone of offended dignity, immediately followed by
    that of the mine manager. It is a significant fact that shortly
    afterwards these two officials purchased a large mill and other
    property at a cost of £10,000, and that the mine yielded for the
    following three years during which I was connected with it an
    average of over 17 dwt. to the ton, as against formerly 10 to 12 dwt.

    “The reader must draw his own conclusions. I used to make it a
    practice to visit the mine daily and prospect the ore, and having
    the mine and mill managers’ daily prospecting as a guide as well
    as my own, every man at the mill knew it was impossible for them
    to thieve without my detecting it; moreover, I made it a rule to
    discharge any of the mill employés that I discovered were interested
    in any small private claims.

    “The crux of the whole thing is having a practical miner at the
    head of affairs, and it is impossible for him to thieve if the work
    is carried out in the manner I have described.”

To bring the whole matter to a conclusion. It may be taken as a safe
axiom that to make gold-mining in the mine as distinct from mining on
the Stock Exchange really profitable the same system of economy, of
practical supervision, and scientific knowledge which is now adopted in
all other businesses must be applied to the raising and extraction of
the metal. Then, and not till then, will genuine mining take the place
to which it is entitled amongst our industries.




    CHAPTER XI

    RULES OF THUMB


This chapter has been headed as above because a number of the rules and
recipes given are simply practical expedients, not too closely
scientific. My endeavour has been to supply practical and useful
information in language as free from technicalities as possible, so as
to adapt it to the ordinary miner, mill operator and prospector, many of
whom have had no scientific training. Some of the expedients are
original devices educed by necessity, which, we are told, is the mother
of invention; others are hints given by practical old prospectors who
had met with difficulties that would be the despair of a man brought up
within reach of forge, foundry, machine shop, or tradesmen generally.
There are many highly ingenious and useful contrivances besides these I
have given.


    LIVING PLACES

The health of the prospector, especially in a new country, depends
largely on his housing--in which particular many men are foolishly
careless, for although they are aware that they will be camped out for
long periods, yet all the shelter they rely on is a miserable calico
tent, often without a “fly,” while in some cases they sometimes even
sleep on the wet, or dusty, ground. Such persons fully deserve the ill
health which sooner or later overtakes them. A little forethought and
very moderate ingenuity would render their camp comparatively healthy
and comfortable.

In summer a tent is the hottest, and in winter the coldest of domiciles.
The “pizie” or “adobie” hut, or, where practicable, the “dugout” are
much to be preferred, especially the latter. “Pizie” or “adobie” is
simply surface soil kneaded with water and either moulded between
boards like concrete, to construct the walls, or made into large
sun-dried bricks. Salt water should not be used, as it causes the wall
to be affected by every change of weather. A properly constructed house
of this material, where the walls are protected by overhanging eaves, is
practically everlasting, and some have been standing for centuries.
There are buildings of pizie or adobie in Mexico, California, and
Australia which are as good as new, although the latter were built
nearly a hundred years ago.

Adobie dwellings are warm in winter, cool in summer, and clean and
healthy if occasionally whitewashed.

The dugout is even more simple in construction. A cutting, say ten feet
wide, is put into the base of a hill for, say, twelve feet until the
back wall is, say, ten feet high, the sides starting from nothing to
that height. The front and such portion as is required of the side walls
are next constructed of pizie or rough stone, with mud mortar, and the
roof either gabled or skillion of bough, grass, or reed thatch, and
covered with pizie, over which is sometimes put another thin layer of
thatch to prevent the pizie being washed away by heavy rain. Nothing can
be more snug and comfortable than such a house, unless the cows, as Mark
Twain narrates, make things “monotonous” by persistently tumbling down
the chimney.

When the Burra copper mines were in full work in South Australia sixty
years ago, the banks of the Burra Creek were honeycombed like a rabbit
warren with the “dugout” homes of the Cornish miners. The ruins of these
old dugouts now extend for miles, and look something like an uncovered
Pompeii.[3]

    [3] This wonderful copper occurrence has lately been revived
    by the discovery of rich and strong lode formations outside the
    formerly worked portions.

When water is scarce and the tent has to be retained, much can be done
to make the camp snug. I occupied a very comfortable camp once, of which
my then partner, a Dane, was the architect. We called it “The Bungalow,”
and it was constructed as follows: First we set up our tent, 10 ft. by 8
ft., formed of green baize-lined calico, and covered with a well set fly
(Fig. 27).

Next we put in four substantial forked posts about 10 ft. high and 15
ft. apart, with securely fixed cross pieces, and on the top was laid a
rough flat roof of brush thatch; the sides were then treated in the same
way, but not so thickly, being merely intended as a breakwind.

    [Illustration: FIG. 27. CALICO TENT WITH FLY.]

The ground plan was as shown in Fig. 28.

    [Illustration: FIG. 28.]

The tent with its two comfortable bunks was placed a little to one side,
the remaining space being used as a dining and sitting room all through
the summer. Except in occasional seasons of heavy rain, when we were
saved the trouble of washing our dishes, the tent was only used for
sleeping purposes, and as a storehouse for clothes and perishable
provisions. I have “dwelt in marble halls” since then, but never was
food sweeter or sleep sounder than in the old bush bungalow.


    A BUSH BED.

To make a comfortable bush bedplace, take four forked posts about 3 ft.
6 in. long and 2 to 3 in. in diameter at the top; mark out your bedplace
accurately and put a post at each corner, about 1 ft. in the ground.
Take two poles about 7 ft. long, and having procured two strong
five-bushel corn sacks, cut holes in the bottom corners, put the poles
through, bringing the mouths of the sacks together, and secure them
there with a strong stitch or two. Put your poles on the upright forked
sticks, and you have a couch that even Sancho Panza would have envied.
It is as well to fix stretchers or cross stays between the posts at head
and foot (Fig. 29).

    [Illustration: FIG. 29. BUSH STRETCHER.]

In malarial countries, sleeping on the ground is distinctly dangerous,
and as such districts are usually thickly timbered, the Northern
Territory hammock is an admirable device, more particularly where
mosquitoes abound.


    NORTHERN TERRITORY HAMMOCK.

This hammock, which is almost a standing bedplace when rigged, is
constructed as follows:--To a piece of strong canvas 7 feet long and
2½ feet wide, put a broad hem, say 3½ inches wide at each end.
Into this hem run a tough stick, about 2 feet 8 inches long by 1½
inches diameter. Round the centre of the stick pass a piece of strong
three-quarter inch rope, 8 to 10 feet long and knot it, so as to leave a
short end in which a metal eye is inserted. To each end of the two
sticks a piece of quarter-inch lashing, about 6 feet long, is securely
attached (Fig. 30).

    [Illustration: FIG. 30. NORTHERN TERRITORY HAMMOCK.]

To make the mosquito covering take 18 feet of ordinary strong cheese
cloth, and two pieces of strong calico of the same size as the canvas
bed; put hems in the ends of the upper one large enough to take
half-inch sticks, to all four extremities of which 8 feet of whipcord is
to be attached. The calico forms the top and bottom of what we used to
call the “meat safe,” the sides being of cheese cloth. A small, flapped
opening is left on the lower side. When once inside you are quite safe
from mosquito bites.

To rig the above, two trees are chosen 7 to 8 feet apart, or two stayed
poles can be erected if no trees are available. The bed is rigged about
3 feet from the ground by taking the rope round the trees or poles, and
pulling the canvas taut by means of the metal eyelet. Then the lashings
at the extremities of the sticks are fixed about 3 feet further up the
trees and you have a bed something between a hammock and a standing bed.
The mosquito net is fixed above the hammock in a similar manner, except
that it does not require the centre stay (Fig. 31).

    [Illustration: FIG. 31. NORTHERN TERRITORY HAMMOCK (SET UP).]

An old friend of mine once had a rather startling experience which
caused him to swear by the Northern Territory hammock. He was camped
near the banks of a muddy creek on the Daly River, and had fortunately
hung his “meat safe” about four feet high. The night was very dark, and
some hours after retiring he heard a crash among his tin camp utensils,
and the noise of some animal moving below him. Thinking his visitor was
a stray “dingo,” or wild dog, he gave a yell to frighten the brute away,
and hearing it go, he calmly went to sleep again. Had he known who his
caller really was, he would not have felt so comfortable. In the morning
on the damp ground below, he found the tracks of a fourteen foot
alligator, which was also out prospecting, but which, fortunately, had
not thought of investigating the “meat safe.”


    PURIFYING WATER.

There is not a more fertile disease distributor, particularly in a new
country, than water. The uninitiated generally take it for granted that
so long as water looks clear it is necessarily pure and wholesome; as a
matter of fact the contrary is more usually the case, except in very
well watered countries, and such, as a rule, are not those in which gold
is most plentifully got by the average prospector. I have seen foolish
fellows, who were parched with a long tramp, drink water in quantity in
which living organisms could be seen with the naked eye, without taking
even the ordinary precaution of straining it through a piece of linen.
If they contracted hydatids, typhoid fever, or other ailments, which
thin our mining camps of the strong, lusty, careless youths, who could
wonder?

The best of all means of purifying water from organic substances is to
boil it. If it should be very bad, add carbon in the form of the
charcoal from your camp fire. If it be thick, you may, with advantage,
add a little of the ash also.

I once rode forty-five miles with nearly beaten horses to a native well,
or rock hole, to find water, the next stage being over fifty miles
farther. The well was found, but the water in it was very bad; for in it
was the body of a dead kangaroo, which had apparently been there for
weeks. The wretched horses, half frantic with thirst, did manage to
drink a few mouthfuls, but we could not. I filled our largest billycan,
holding about two gallons, slung it over the fire and added, as the wood
burnt down, charcoal, till the top was covered to a depth of two inches.
With the charcoal there was, of course, a little ash containing
bi-carbonate of potassium. The effect was marvellous. So soon as the
horrible soup came to the boil, the impurities coagulated, and after
keeping it at boiling temperature for about a quarter of an hour, it was
removed from the fire, the cinders skimmed out, and the water allowed to
settle, which it did very quickly. It was then decanted off into an
ordinary prospector’s pan, and some was used to make tea (the flavour of
which can be better imagined than described); the remainder was allowed
to stand all night, a few pieces of charcoal being added. In the morning
it was bright, clear, and absolutely sweet. This experience is worth
knowing, as many a bad attack of typhoid and other fevers would be
averted if practical precautions of this kind were but used.


    TO OBTAIN WATER FROM ROOTS.

The greatest necessity of animal life is water. There are, however, vast
areas of the earth’s surface where this most precious element is
lamentably lacking, and such, unfortunately, is the case in many rich
auriferous districts.

To the practical man there are many indications of water. These, of
course, vary in different countries. Sometimes it is the herbage, but,
probably, the best of all is the presence of carnivorous animals and
birds. These are never found far from water. In Australia the not
over-loved wily old crow is a pretty sure indicator of water within
reasonable distance--water may be extracted from the roots of the Mallee
(_Eucalyptus dumosa_ and _gracilis_)--the Box (_Eucalyptus hemiphloia_)
and the Water Bush (_Hakea leucoptera_). To extract it the roots are dug
up, cut into lengths of about a foot, and placed upright in a can; the
lower ends being a few inches above the bottom. It is simply astonishing
how much wholesome, if at times somewhat astringent, water may thus be
obtained in a few hours, particularly at night.

_Hakea leucoptera._ “Pins and needles.”--Maiden, in his work “Useful
Native Plants of Australia,” says: “In an experiment on a water-yielding
_Hakea_, the first root, about half an inch in diameter and six or eight
feet long, yielded quickly, and in large drops about a wine-glass full
of really excellent water.”

This valuable, though not particularly ornamental shrub (for it never
attains to the dimensions of a tree), is found, to the best of my
belief, in all parts of Australia, although it is said to be absent
from West Australia. As to this, I don’t feel quite sure. I have seen
it “from the centre to the sea” as far west as Streaky Bay, and believe
I have seen it farther west still. Considering the great similarity of
much of the flora of South Africa to that of Australia, it is probable
that some species of the water-bearing _Hakea_ may be found there. It
can readily be recognised by its acicular, needle-like leaves, and more
particularly by its peculiarly shaped seed vessel, which resembles the
pattern on an old-fashioned Indian shawl (Fig. 32).

If the water found is too impure for drinking purposes and the trouble
arises from visible animalculæ only, straining through a
pocket-handkerchief is better than nothing; the carbon filter is better
still; but nothing is so effective as boiling. A carbon filter is a tube
with a wad of compressed carbon inserted, through which the water is
sucked. As a rule clay- water is comparatively innocuous, but
beware of the bright, limpid water of long stagnant rock water-holes.

    [Illustration: FIG. 32. SEED-VESSEL OF HAKEA LEUCOPTERA.]


    TO MAKE AN EFFECTIVE FILTER.

Take a nail-can, keg, cask, or any other vessel, or even an ordinary
wooden case (well tarred inside, if possible, to make it water-tight).
Make a hole or several holes in the bottom, and set it over a tank or
bucket. Into the bottom of the filter put (1) a few inches of washed
broken stone; (2) about four inches of charcoal; (3) say three inches of
clean coarse sand (if not to hand you can manufacture it by crushing
quartz with your pestle and mortar), and (4) alternate layers of
charcoal and sand until the vessel is half filled. Fill the top half
with water, and renew from time to time, and you have a filter which is
as effective as the best London made article. _But it is better to boil
your water whether you filter afterwards or not._

Clear the inside of the water-cask frequently, and occasionally add to
the water a little Condy’s fluid, as it destroys organic matter. A
useful cement for stopping leaky places in casks is made as follows;
Tallow 25 parts, lard 40 parts, sifted wood ash 25 parts. Mix together
by heating, and apply with a knife blade which has just been heated.


    CANVAS WATER BAGS.

    [Illustration: FIG. 33. CANVAS WATER BAG.]

Are easily made, and are very handy for carrying small supplies of
drinking-water when prospecting in a dry country; they having the
advantage of keeping the water cool in the hottest weather, by reason of
the evaporation. The mouthpiece is made of the neck of a bottle securely
sewn in (Fig. 33).


    MEDICINE CASE.

Medicine is also a matter well worthy of thought. The author’s worst
enemy would not call him a mollycoddle, yet he has never travelled in
far wilds without carrying something in the way of medicine. First,
then, on this subject, it cannot be too often reiterated that if common
Epsom salts were a guinea an ounce instead of a penny the medicine would
be valued accordingly, but it is somewhat bulky. What I specially
recommend, however, is a small pocket-case of the more commonly known
homoeopathic remedies, “Mother tinctures,” or first dilutions, which
are small, light, and portable, with a small simple book of
instructions. Though generally an allopath in practice, I once saved my
own life, and have certainly helped others by a little knowledge in
diagnosing complaints and having simple homoeopathic remedies at hand
to be used in the first stages of what might otherwise have been serious
illnesses.


    PRODUCING FIRE.

Every one has heard, and most believe, that fire may be easily produced
by rubbing together two pieces of wood. I have seen it done by
aboriginals, but they seldom make use of the operation, which is
generally laborious, preferring to carry lighted fire sticks for miles.
I have never succeeded in the experiment.

Sometimes, however, it is almost a matter of life or death to be able to
produce fire. The back of a pocket knife, or an old file with a fragment
of flint, quartz, or pyrites struck smartly together over the remains of
a burnt piece of calico, will in deft hands produce a spark which can be
fanned to a glow, and so ignite other material, till a fire is produced.

Also it may not be generally known that he who carries a watch has a
“burning glass” with which he can, in clear weather, produce fire at
will. All that is required is to remove the glass of your watch and
carefully three parts fill it with water (salt or fresh). This forms a
lens which, held steadily, will easily ignite any light, dry,
inflammable substance.

When firearms are carried, cut a cartridge so that only about a quarter
of the charge of powder remains. Damp some powder and rub it on a small
piece of dry cotton cloth or well-rubbed brown paper. Push a loose
pellet of this into the barrel, insert your half cartridge, fire at the
ground, when the wad will readily ignite, and can be blown into flame.


    TO COPY CORRESPONDENCE.

The prospector is not usually a business man; hence in dealing with
business men who, like Hamlet, are “indifferent honest,” he frequently
comes to grief through not having a copy of his correspondence. It is
most desirable, therefore, either to carry a carbon paper duplicating
book and a stylus, or by adding a little sugar to good ordinary black
ink you may make a copying ink; then with the aid of a “yellow back”
octavo novel, two pieces of board, and some ordinary tissue paper, you
may take a copy of any letter you send.


    TO PROVIDE A SIMPLE TELEGRAPHIC CODE.

Buy a couple of cheap small dictionaries of the same edition, send one
to your correspondent with an intimation that he is to read up or down
so many words from the one indicated when receiving a message. Thus, if
I want to say “Claim is looking well,” I take a shilling dictionary,
send a copy thereof to my correspondent with the intimation that the
real word is seven down, and telegraph--“Civilian looking weird;” this,
if looked up in Worcester’s little pocket dictionary, for instance, will
read “Claim looking well.” Any dictionary will do so long as both
parties have a copy and understand which is the right word. By
arrangement this plan can be varied from time to time if you have any
idea that your code can be read by others.


    A SERVICEABLE SOAP.

Wood ashes from the camp fire are boiled from day to day in a small
quantity of water, and allowed to settle, the clear liquid being
decanted off. When the required quantity of weak lye has been
accumulated, evaporate by boiling, till a sufficient degree of strength
has been obtained. Now melt down some mutton fat, and, while hot, add to
the boiling lye. Continue boiling and stirring till the mixture is about
the consistency of thick porridge, pour into any convenient flat vessel,
and let it stand till cool. If you have any resin in store, a little
powdered and added gradually to the melting tallow, before mixing with
the lye, will stiffen your soap.


    TO CROSS A FLOODED STREAM.

Take a half-gallon, or larger, tin “billy can,” enclose it in a strong
cotton handkerchief or cotton cloth, knotting same over the lid, invert,
and, taking the knot in the hand, you have a floating appliance which
will sustain you in any water, whether you are a swimmer or not. The
high silk hat of civilisation would act as well as the can, but these
are not usually found far afield.


    TO MAKE A HIDE BUCKET.

At times when prospecting in an “incline” or “underlay” shaft,
particularly where the walls of the lode are irregular, a hide bucket
will be found preferable to an iron one. The mode of manufacture is as
follows: Procure an ox hide, “green,” if possible; if dry, it should be
soaked until quite soft. Cut some thin strips of hide for sewing or
lacing. Now shape a bag or pocket of size sufficient to hold about a
hundred-weight of stone, and by puncturing the edges with a knife,
marline-spike, or other pointed tool, sew together; make a handle of
twisted or pleated hide, and having filled your bucket with dry sand or
earth let it stand till the whole is quite dry, when it will be properly
distended and will maintain its shape until worn out.


    TO MAKE A “SLUSH LAMP.”

Where candles are scarce and kerosine is not, a “slush lamp” is a useful
substitute. Take an old but sound quart tin pannikin, half fill it with
sand or earth, and prepare a thin stick of pine, round which wrap a
strip of soft cotton cloth. The stick should be about half an inch
longer than the depth of the pannikin. Melt some waste fat, fill the
pannikin therewith, push the stick down into the earth at the bottom,
and you have a light, which, if not equal to the electric or
incandescent gas burner, is quite serviceable. In Australia the soft
velvety core of the “bottle brush” or honeysuckle tree, _Banksia
marginata_, is often used instead of the cotton wick.




    CHAPTER XII

    RULES OF THUMB

    MINING APPLIANCES AND METHODS

    A TEMPORARY FORGE.


What prospector has not at times been troubled for the want of a forge?
To steel or harden a pick, or sharpen a drill is comparatively easy, but
there is often a difficulty in getting a forge. Big single action
bellows are sometimes bought at great expense, and some ingenious
fellows have made an imitation of the blacksmith’s bellows by means of
sheepskins and rough boards.

With inadequate material and appliances to hand, the following will be
found easier to construct and more lasting when constructed. Only a
single piece of iron is required, and, at a pinch, one could even
dispense with that by using a slab of talcose material, roughly shaping
a hearth therein and making a hole for the blast. First, construct a
framing about the height of an ordinary smith’s forge. This can be made
with saplings and bark, or better still, if available, out of an empty
packing case about three feet square. Fill the frame or case with
slightly damped earth and ram it tight, leaving the usual hollow hearth.
Then form a chamber below the perforated hearth opening to the rear. Now
construct a centrifugal fan, such as is used for the ventilation of
shallow shafts and workings. Set this up behind the hearth and revolve
by means of a wooden multiplying wheel. A piece of ordinary washing line
rope, or sash line rope, well resined if resin can be got--but pitch,
tar, or wax will do by adding a little fine dust to prevent sticking--is
used as a belt. With very rough materials a handy man can thus make a
forge that will answer ordinary requirements.--N.B. Do not use clay for
your hearth bed unless you can get a highly aluminous clay, and can give
it full time to dry before the forge fire is lit. Ordinary surface soil,
not too sandy, acts well, if damped and rammed thoroughly. Of course, if
you can get an iron nozzle for your blower the whole operation is
simplified.


    SIMPLE WAY OF MAKING CHARCOAL.

Dig a pit 5 feet square by 3 feet deep and fill with fuel. After
lighting, see that the pit is kept full. The hot embers will gradually
sink to the bottom. The fuel should be kept burning fiercely until the
pit seems almost full, when more fuel should be added, raising the heap
about a foot above the level of the ground. The earth dug out of the pit
should then be shovelled back over the burning mass. After leaving it to
cool for 24 hours the pit will be found nearly full of charcoal. About
one-quarter the weight of the dry fuel used should be recovered in
charcoal.


    ROUGH SMELTING ON THE MINE.

Rough gold smelting on the mine is effected with a flux of borax,
carbonate of soda, or, as I have often done, with some powdered white
glass. When the gold is smelted and the flux has settled down quietly in
a liquid state, the bulk of the latter may be removed, to facilitate
pouring into the mould, by dipping an iron rod alternately into the flux
and then into a little water, and knocking off the ball of congealed
flux which adheres after each dip. This flux should, however, be crushed
with a pestle and mortar and panned off, as, in certain cases, it may
contain tiny globules of gold.


    MISFIRES IN BLASTING.

One of the most common sources of accident in mining operations is due
either to carelessness or to the use of defective material in blasting.
A shot misses, generally for one of two reasons; either the explosive,
the cap, or the fuse (most often the latter), is inferior or defective;
or the charging is incompetently performed. Sometimes the fuse is not
placed properly in the detonator, or the detonator is not properly
enclosed in the cartridge, or the fuse is injured by improper tamping.
If several shots have been fired together, particularly at the change of
a “shift,” the men who have to remove the broken material may in so
doing explode the missed charge. Or, more inexcusable still, men will
often be so foolish as to try to clear out the drill hole and remove the
missed cartridge. When a charge is known to have missed all that is
necessary to do in order to discharge it safely is to remove a few
inches of “tamping” from the top of the drill hole, place in the bore a
plug of dynamite with cap and fuse attached, put an inch or two of
tamping over it and fire, when the missed charge will also be exploded.
Of course, judgment must be used and the depth of the drill taken into
consideration. As a rule, miners use far more tamping than is at all
requisite. The action of the charge will generally be found quite as
effective with a few inches of covering matter as with a foot or more,
while the exploding of misfire cartridges is rendered simple, as no
removal of tamping is required before placing the top “plug” in case of
misfire.


    TO PREVENT LOSS OF RICH SPECIMENS IN BLASTING.

When blasting the cap of a lode, particularly on rich shutes of gold,
the rock is apt to fly, and rich specimens may be thrown far afield and
so be lost. A simple way of avoiding this is to procure a quantity of
boughs, which tie into loose bundles, placing the leafy parts
alternately end for end. Before firing, pile these bundles over the
blast and, if care is used, very few stones will fly. The same device
may be used in wide shallow shafts.


    A SIMPLE MODE OF RETORTING SMALL QUANTITIES OF AMALGAM.

Clean your amalgam and squeeze it as hard as possible through strong
calico or chamois leather. Take a large sound potato, cut off about a
quarter from one end and scoop out a hole in the centre about twice as
big as the ball of amalgam. Procure a piece of flat iron--an old spade
will do as well as anything--insert the amalgam, and, having placed the
potato, cut side downwards, thereon, put the plate of iron on the forge,
heat up first gently, then stronger, till separation has taken place,
when the gold will be found in a bright clean button on the plate and
the mercury in fine globules in the potato, from which it can be
re-collected by breaking up the partly or wholly cooked tuber under
water in an enamelled or ordinary crockery basin. It is as well to place
a piece of paper between the iron and the amalgam to prevent adhesion.


    TO RETORT SMALL QUANTITIES OF MERCURY FOR AMALGAMATING ASSAY TESTS.

    [Illustration: FIG. 34. SMOKING-PIPE RETORT.]

Get two new tobacco pipes similar in shape (Fig. 34), with the biggest
bowls and longest stems procurable. Break off the stem of one close to
the bowl and fill the hole with well worked clay (some battery slimes
make the best luting clay). Set the stemless pipe on end in a clay bed,
and fill with amalgam, pass a bit of thin iron or copper wire beneath
it, and bend the ends of the wire upwards. Now fit the whole pipe, bowl
inverted, on to the under one, luting the edges of both well with clay.
Twist the wire over the top with a pair of nippers till the two bowls
are fitted closely together, and you have a retort that will stand any
heat necessary to thoroughly distil mercury.


    A SIMPLE MODE OF ASCERTAINING THE NOMINAL HORSE-POWER OF AN
    ENGINE.

Multiply the internal diameter of the cylinder by itself and strike off
the last figure of the quotient. The diameter is

     20” × 20”
     20
    -----
     40ø.    The H.P. is 40.

The following rules will be found more professionally accurate from an
engineering standpoint, though the term “horse-power” is not now
generally employed.

_To find the Nominal Horse-power._--For _non-condensing_ engines:
Multiply the square of the diameter of the cylinder in inches by 7 and
divide the product by 80. For _condensing_ engines: Multiply the square
of the diameter of the cylinder in inches by 7 and divide the product by
200.

_To find the Actual Horse-power_ of an engine, multiply the area of the
cylinder in square inches by the average effective pressure in pounds
per square inch, less 3 lb. per square inch as the frictional allowance,
and also by the speed of the piston in feet per minute, dividing the
product by 33,000, and the quotient will be the actual horse-power.


     “SCALING” COPPER PLATES.

To “scale” copper plates they may be put over a charcoal or coke fire to
slowly sublimate the quicksilver. Where possible, the fireplace of a
spare boiler can be utilised, using a thin red fire. After the entire
evaporation of the quicksilver the plates should be slowly cooled,
rubbed with hydrochloric acid, and put in a damp place overnight, then
rubbed with a solution of sal ammoniac and nitre in equal parts, and
again heated slowly over a red fire. They must not be allowed to get red
hot; the proper degree of heat is indicated by the gold scale rising in
blisters, when the plates are to be taken from the fire and the gold
scraped off. Any part of the plate on which the gold has not blistered
should be again rubbed with the solution and fired. The gold scale
should be collected in a glass or earthen dish and covered with nitric
acid, till all the copper is dissolved, when the gold can be smelted in
the usual way; but when it is molten, corrosive sublimate should be put
in the crucible till a blue flame ceases to be given off.


    _A Second Method._

The simplest plan I know is to have a hole dug nine inches deep by about
the size of the plate to be scaled; place a brick at each corner, and on
each side, halfway between. Get up a good fire, and let it burn down to
strong embers, or use charcoal, then place the plate on three bars of
iron extending between the three pairs of bricks, have a strong solution
of borax ready in which soak strips of old “table blanket,” laying these
over the plate and sprinkling them with the borax solution when the
plate gets too hot. After a time the deposit of mercury and gold on the
plate will assume a white, efflorescent appearance, and may then be
readily parted from the copper.


    _Another Method._

Heat the plate over an open fire, to drive off the mercury; after which,
let it cool, and saturate with dilute sulphuric acid for three hours, or
longer; then sprinkle over the surface a mixture of equal parts of
common salt and sal ammoniac, and heat to redness. When cool, the gold
scale comes off freely; the scale is then boiled in nitric or sulphuric
acid, to remove the copper, previous to melting. Plates may be scaled
about once in six months, and will under ordinary circumstances produce
about one ounce of clean gold for each superficial foot of copper
surface employed. I always paint the back of the plate with a mixture of
boiled oil and turpentine, or beeswax dissolved in turpentine, to
prevent the acid attacking the copper.


     HOW TO SUPPLY MERCURY TO MORTAR BOXES.

I am indebted for the following to Mr. J. M. Drake, who, speaking of his
experience on the Wentworth Mine, N.S.W., says:--

     “Fully 90 per cent. of the gold is saved on the outside
     plates, only a small quantity remaining in the mortar. The plates
     have a <DW72> of 2 in. to 1 ft. No wells are used, the amalgam
     traps saving any quicksilver which may leach off the plates. The
     quicksilver is added every hour in the mortar. The quantity is
     regulated by the mill manager in the following manner: Three pieces
     of wood, 8 in. wide by 12 in. long by 2 in. thick, have 32 holes
     1 in. deep bored in each of them. These holes will just take a
     small 2 oz. phial. The mill manager puts the required quantity of
     quicksilver in each bottle and the batteryman empties one bottle in
     each mortar every hour; and puts it back in its hole upside down.
     Each block of wood lasts eight hours, the duration of one man’s
     shift.” This of course is for a 20-head mill with four mortars or
     “boxes.”

I commend this as an excellent mode of supplying the mercury
to the boxes or mortars. The quantity to be added depends on
circumstances. A careless battery attendant will often put in too
much or too little when working without the automatic feeder.
I have known an attendant on suddenly awaking to the fact half
through his shift, that he had forgotten to put in any mercury,
to then empty into the stamper box two or three pounds weight;
with what effect may be easily surmised.


     HOW WATER SHOULD ENTER STAMPER BOXES.

The following extract which relates to Californian Gold Mill practices
is from Bulletin No. 6 of the California State Mining Bureau. I quite
agree with the practice.

    “The battery water should enter both sides of the mortar in an
    even quantity, and should be sufficient to keep a fairly thick
    pulp which will discharge freely through the grating or screen.
    About 120 cubic feet of water per ton of crushed ore may be
    considered an average, or 8 to 10 cubic feet per stamp per hour.

    “Screens of different materials and with different orifices are
    used; the materials comprise wire cloth of brass or steel, tough
    Russian sheet iron, English tinned plate, and, quite recently,
    aluminium bronze. The ‘aluminium bronze’ plates are much longer
    lived than either of the other kinds, and have the further
    advantage that, when worn out, they can be sold for the value of
    the metal for remelting; these plates are bought and sold by the
    pound, and are said to contain 95 per cent. of copper and 5 per
    cent. of aluminium. Steel screens are not so much used, on
    account of their liability to rust.”

I have had no experience with the aluminium bronze screen. I presume,
however, that it is used only for mills where mercury is not put in the
mortars, otherwise it would surely become amalgamated. The same remark
applies to brass wire cloth and tinned plate. Unless the metal of which
they are composed will not readily amalgamate with mercury, I should be
chary of using new screen devices. Mercury is a most insidious metal and
is often found most unexpectedly in places in the battery where it
should not be. Probably aluminium steel would be better than any
substance mentioned. It would be hard, light, strong, and not readily
corrodible. I am not aware if it has been tried.

Under the heading of “Power for Mills” the following is taken from the
same source.


     POWER FOR MILLS.

    “As the Pelton wheel seems to find the most frequent application
    in California, it may be convenient for millmen to have the
    following rule, applicable to these wheels:

    “When the head of water is known in feet, multiply it by
    0·0024147, and the product is the horse-power obtainable from one
    miner’s inch of water.

    “The power necessary for different mill parts is:

 For each 850lb. stamp, dropping 6 inches 95 times per minute, 1·33 h.p.
   ”      750      ”          ”            ”        ”          1·18  ”
   ”      650      ”          ”            ”        ”          1·00  ”
 For an 8-inch by 10-inch Blake pattern rock-breaker           9·00  ”
 For a Frue or Triumph vanner, with 220 revolutions per minute,0·50  ”
 For a 4-feet clean-up pan, making   30         ”         ”    1·50  ”
 For an amalgamating barrel, making  30         ”         ”    2·50  ”
 For a mechanical batea, making      30         ”         ”    1·00  ”

The writer has had small practical experience of the working of that
excellent hydraulic motor, the Pelton wheel, but if by horse-power in
the table given is meant nominal horse-power, it appears to be high.
Working with 800 cwt. stamps, 80 blows a minute, 1 h.-p. nominal per
stamp will be found sufficient with any good modern engine, which has no
further burden than raising the stamps and pumping the feed water. It is
always well, however, particularly when providing engine power, to err
on the right side, and make provision for more than is absolutely needed
for actual battery requirements. This rule applies with equal potency to
pumping engines.


     TO AVOID LOSS IN CLEANING UP.

The following, is a hint to quartz mill managers with respect to that
common source of loss of gold involved in the almost inevitable loss of
mercury in cleaning up operations. I have known hundreds of pounds’
worth of gold to be recovered from an old quartz mill site by the simple
process of washing up the ground under the floor.

If you cannot afford to floor the whole of the battery with smooth
concrete, at all events smoothly concrete the floor of the cleaning-up
room, and let the floor <DW72> towards the centre: where a sink is
provided. Any lost mercury must thus find its way to the centre, where
it will collect and can be panned off from time to time. Of course an
underground drain and mercury trap must be provided.


     IRON EXTRACTOR.

When using self-feeders, fragments of steel tools are especially liable
to get into the battery boxes or other crushing appliance where they
sometimes cause great mischief. I believe the following plan would be a
practicable remedy for this evil.

By a belt from the cam or counter shaft, cause a powerful electric
magnet to extract all magnetic particles; then, by a simple ratchet
movement, at intervals withdraw the magnet and drop the adhering
fragments into a receptacle by automatically switching off the electric
current. A powerful ordinary horse-shoe magnet might probably do just as
well, but would require to be re-magnetised from time to time.


     TO SILVER COPPER PLATES.

To silver copper plates, that is, to amalgamate them on the face with
mercury, is really a most simple operation, though many battery men make
a great mystery of it. Indeed, when I first went into a quartz mill the
process deemed necessary was not only a very tedious one, but very dirty
also.

To amalgamate with silver, in fact, to silver-plate your copper without
resort to the electro-plating bath, take any old silver (failing that,
silver coin will do, but is more expensive), and dissolve it in somewhat
dilute nitric acid, using only just sufficient acid as will effect the
purpose. When the crystals have formed, add sufficient clean quick
mercury to form a thick pasty amalgam; moderate heat will assist the
process. After some hours place the ball of amalgam in a piece of strong
new calico and squeeze out any surplus mercury.

About an ounce of silver to the foot of copper is sufficient. To apply
it on new plates use somewhat dilute nitric acid applied with a swab to
free the surface of the copper from oxides or impurities, then rub the
ball of amalgam over the surface, using some little force. It is always
well when copper-plates are coated with silver or zinc by means of
mercury to let them stand dry for a day or two before using, as the
mercury oxidises and the coating metal more closely adheres.

Only the very best copper-plate procurable should be used for battery
tables; bad copper will always give trouble, both in the first “curing,”
and after treatment. It should not be heavily rolled copper, as the more
porous the metal the more easily will the mercury penetrate and
amalgamate. I cannot agree that any good is attained by scouring the
plates with sand and alkalies, as recommended in some books on the
subject; on the contrary, I prefer the opposite mode of treatment, and
either face the plates with nitrate of silver and nitrate of mercury, or
else with sulphate of zinc and mercury, in the form of what is called
zinc amalgam. If mine water, which often contains free sulphuric acid,
is being used, the latter plan is preferable.

The copper should be placed smoothly on the wooden table and secured
firmly thereto by copper tacks. If the plate should be bent or buckled,
it may be flattened by beating it with a heavy hammer, taking care to
interpose a piece of inch-thick soft wood between hammer and plate.

To coat with mercury only, procure some nitrate of mercury. This is
easily made by placing mercury in a glazed earthenware bowl, pouring
somewhat dilute nitric acid on it, and letting it stand till the
metallic mercury is changed to a white crystal. Dense reddish-brown
fumes will arise, which are injurious if breathed, so the operation
should be conducted either in the open air, or where there is a draught.

Now have your silvering solution ready, which is to be somewhat diluted
with water, next take two swabs, with handles about 12 inches long, dip
the first into a basin containing dilute nitric acid, and rub it rapidly
over about a foot of the surface of the plate; the oxide of copper will
be absolutely removed, and the surface of the copper rendered pure and
bright; then take the other swab, wet with the dilute nitrate of
mercury, and pass it over the clean surface, rubbing it well in.
Continue this till the whole plate has a coating of mercury. It may be
well to go over it more than once. Then turn on the water and wash the
plate clean, sprinkle with metallic mercury, rubbing it upwards until
the plate will hold no more.

A basin with nitrate of mercury may be kept handy, and the plates
touched up from time to time for a few days until they get amalgamated
with gold, after which, unless you have much base metal to contend with,
they will give no further trouble.

It must be remembered, however, that an excessive use of nitric acid
will result in waste of mercury, which will be carried off in a milky
stream with the water; and also that it will cause the amalgam to become
very hard, and less active in attracting other particles of gold.

If you are treating the plate with nitrate of silver prepared as already
mentioned, clean the plate with dilute nitric acid, rub the surface with
the ball of amalgam, following with the swab and fairly rubbing in. It
will be well to prepare the plate some days before requiring to use it,
as a better adhesion of the silver and copper takes place than if
mercury is applied at once.

To amalgamate with zinc amalgam, clean the copper plate by means of a
swab, with fairly strong sulphuric acid diluted with water; then while
wet apply the zinco-mercury amalgam and well rub in. To prepare the zinc
amalgam, clip some zinc (the lining of packing cases will do) into small
pieces and immerse them in mercury after washing them with a little weak
sulphuric acid and water to remove any coating of oxide. When the
mercury will absorb no more zinc, squeeze through chamois leather or
calico (as for silver amalgam), and well rub in. The plate thus prepared
should stand for a few days, dry, before using. If, before amalgamation
with gold takes place, oxide of copper or other scum should rise on this
plate a little very dilute sulphuric acid will instantly remove it.

Sodium and cyanide of potassium are frequently used in dressing-plates,
but the former should be very sparingly employed, as it will often do
more harm than good by taking up all sorts of base metals with the
amalgam, and so presenting a surface which the gold will pass over
without adhering to. Where water is scarce, and is consequently used
over and over again, lime may be added to the pulp, or, if lime is not
procurable, wood ashes may be used. The effect is two-fold; the lime not
only tends to “sweeten” sulphide ores and keep the tables clean, but
also causes the water to cleanse itself more quickly of the slimes,
which will be more rapidly precipitated. When zinc amalgam is used,
alkalies would, of course, be detrimental.

When no other water than that from the mine is available, difficulties
often arise owing to the impurities it contains. These are various, but
among the most common are the soluble sulphates, and sometimes free
sulphuric acid evolved by the oxidisation of metallic sulphides. In the
presence of this difficulty, do one of two things: either _utilise_ or
_neutralise_. In certain cases, I recommend the former. Some time since
I was treating, for gold extraction, material from a mine which was very
complex in character. For this ore I coined the term “polysynthetic.”
This contained about half a dozen different sulphides. The upper parts
of the lode being partially oxidised, free sulphuric acid (H₂SO₄)
was evolved. I therefore, following out a former discovery, added a
little metallic zinc to the mercury in the boxes and on the plates with
excellent results. When the free acid in the ore began to give out in
the lower levels I added minute quantities of sulphuric acid to the
water from time to time. I have since found, however, that with some
water, particularly West Australian, the reaction is so feeble (probably
owing to the lime and magnesia present) as to make this mode of
treatment unsuitable.

    [Illustration: FIG. 35. DOLLY.]

    [Illustration: FIG. 35A. PRIMITIVE DOLLY.]


    HOW TO MAKE A DOLLY.

I have seen some rather elaborate dollies, intended to be worked with
amalgamating tables, but the usual prototype of the quartz mill is set
up, more or less, as follows: A tree stump, from 9 in. to a foot
diameter, is levelled off smoothly at about 2 ft. from the ground; on
this is firmly fixed a circular plate of ½ in. iron, say 9 in. in
diameter; a band of ³/₁₆ in. iron, about 8 or 9 in. in height, fits
more or less closely round the plate (Fig. 35). This is the battery box.
A beam of heavy wood, about 3 in. diameter and 6 ft. long, shod with
iron, is vertically suspended, about 9 in. above the stump, from a
flexible sapling with just sufficient spring in above the stump, from
a flexible sapling with just sufficient spring in it to raise the pestle
to the required height. About 2 ft. from the bottom the hanging beam is
pierced with an auger hole and a rounded piece of wood, 1½ in. by 18
in., is driven through to serve as a handle for the man who is to do the
pounding. His mate breaks the stone to about 2 in. gauge and feeds the
box, lifting the ring from time to time to sweep off the triturated
gangue, which he screens through a sieve into a pan and washes off,
either by means of a cradle or simply by panning. In dollying it
generally pays to burn the stone, as so much labour in crushing is thus
saved. A couple of small kilns to hold about a ton each dug out of a
clay bank will be found to save fuel where firewood is scarce, and will
more thoroughly burn the stone and dissipate the base metals, but it
must be remembered that gold from burnt stone is liable to become so
encrusted with the base metal oxides as to be difficult to amalgamate.
Fig. 35A represents another primitive dolly (Plate VI. hand dollying).

    [Illustration: PLATE VI.--HAND DOLLYING _To face p._ 152]


     ROUGH WINDLASS.

Make two St. Andrew’s crosses with four saplings, the upper angle being
shorter than the lower; fix these upright, one at each end of the shaft;
stay them together by cross pieces till you have constructed something
like a “horse,” such as is used for sawing wood, the crutch being a
little over 3 feet high. Select a log for a windlass barrel, about 6 in.
diameter and a foot longer than the distance between the supports, as
straight as is procurable; cut in it two circular slots about an inch
deep by 2 in. wide to fit into the forks; at one end cut a straight slot
2 in. deep across the face. Now get a crooked bough, as nearly the shape
of a handle as nature has produced it, and trim it into right angular
shape, fit one end into the barrel, and you have a windlass that will
pull up many a ton of stuff.


     PUDDLER.

This is made by excavating a circular hole about 2 ft. 9 in. deep and,
say, 12 ft. in diameter. An outer and inner wall are then constructed of
slabs 2 ft. 6 in. in height to ground level, the outer wall being thus
30 ft. and the inner 15 ft. in circumference. The circular space
between is floored with smooth hard-wood slabs or boards, and the whole
made secure and water-tight. In the middle of the inner enclosure a
stout post is planted, to stand a few inches above the wall, and the
surrounding space is filled up with clay rammed tight. A strong iron pin
is inserted in the centre of the post, on which is fitted a revolving
beam, which hangs across the whole circumference of the machine and
protrudes a couple of feet or so on each side. To this beam are
attached, with short chains, a couple of drags made like V-shaped
harrows by driving pieces of rod iron through a heavy frame, shaped as a
rectangular triangle (Fig. 36).

    [Illustration: FIG. 36. PUDDLING MACHINE (SECTIONAL VIEW).]

    [Illustration: FIG. 37. PUDDLING MACHINE.]

To one end of the beam an old horse is attached, who, as he slowly walks
round the circular track, causes the harrows and drags to so puddle the
washdirt and water in the great wooden enclosure that the clay is
gradually disintegrated, and flows off with the water which is from
time to time admitted. The clean gravel is then run through a “cradle,”
“long Tom,” or “sluice,” and the gold saved. This, of course, is the
simplest form of gold mining. In the great alluvial mines other and more
intricate appliances are used, but the principle of extraction is the
same.


    A MAKESHIFT PUMP.

To make a temporary small “draw-lift” pump, which will work down to a
hundred feet or more if required, take a large size common suction
Douglas pump, and, after removing the top and the handle, fix the pump
as close to the highest level of the water in the shaft as can be
arranged. Now make a square water-tight wooden column of slightly
greater capacity than the suction pipe, fix this to the top of the pump,
and by means of wooden rods, work the whole from the surface, using
either a longer levered handle or, with a little ingenuity, horse-power.
If you can get it the iron downpipe used to carry the water from the
guttering of houses is more easily adapted for the pipe column; then,
also, iron pump rods can be used, but I have raised water between 60 and
70 feet with a large size Douglas pump provided only with a wooden
column and rods.


     SQUEEZING AMALGAM.

For squeezing amalgam, strong calico, not too coarse, previously soaked
in clean water, is quite as good as ordinary chamois leather. Some gold
is fine enough to escape through either.


     MERCURY EXTRACTOR.

The mercury extractor or amalgam separator (Fig. 38) is a machine which
is very simple in construction, and is stated to most efficient in
extracting quicksilver from amalgam, as it requires but from two to
three minutes to extract the bulk of the mercury from one hundred pounds
of amalgam, leaving the amalgam drier than when strained in the ordinary
way by squeezing through chamois leather or calico. The principle is
that of the De Laval cream separator--_i.e._, rapid centrifugal motion.
The appliance is easily put together, and as easily taken apart. The
cylinder is made of steel, and is run at a very high rate of speed.

The general construction of the appliance is as follows: The casing or
receiver is a steel cylinder, which has a pivot at the bottom to receive
the step for an upright hollow shaft, to which a second cylinder of
smaller diameter is attached. The second cylinder is perforated, and a
fine wire cloth is inserted. The mercury, after passing through the
cloth, is discharged through the perforations. When the machine is
revolved at great speed, the mercury is forced into the outside
cylinder, leaving the amalgam, which has been first placed in a calico
or canvas bag, in a much drier state than it could be strained by hand.
While not prepared to endorse absolutely all that is claimed for this
appliance, I consider that it has mechanical probability on its side,
and that where large quantities of amalgam have to be treated it will be
found useful and effective.

    [Illustration: FIG. 38. MERCURY EXTRACTOR.]


     SLUICE PLATES.

I am indebted to Mr. F. W. Drake for the following account of sluice
plates, which I have never tried, but think the device worth attention:

“An addition has been made to the gold-saving appliances by the placing
of what are called in America, ‘sluice plates’ below the ordinary
table. The pulp now flows over an amalgamating surface, 14 ft. long by
4 ft. wide, sloping 1½ in. to the foot, and is then contracted into a
copper-plated sluice 15 ft. long by 14 in. wide, having a fall of 1
in. to the foot. Our mill manager (Mr. G. C. Knapp), advocated these
sluice plates for a long time before I would consent to a trial. I
contended that as we got little or no amalgam from the lower end of our
table plates, there was no gold going away capable of being recovered
by copper plates; and even if it were, narrow sluice plates were a
step in the wrong direction. If anything, the amalgamating surface
should be widened to give the particles of gold a better chance to
settle. His argument was that the conditions should be changed; by
narrowing the stream and giving it less fall, gold, which was incapable
of amalgamation on the wide plates, would be saved. We finally put
one in, and it proved so successful that we now have one at the end
of each table. The percentage recovered on the sluice plates, of the
total yield, varies, and has been as follows:--October, 9·1 per cent.;
November, 6·9 per cent.; December, 6·4 per cent.; January, 4·3 per
cent.; February, 9·3 per cent.”


     MEASURING INACCESSIBLE DISTANCES.

To ascertain the width of a difficult gorge, a deep river, or
treacherous swamp without crossing and measuring, sight a conspicuous
object at the edge of the bank on the farther side; then as nearly
opposite and square as possible plant a stake about five feet high, walk
along the nearer margin to what you guess to be half the distance across
(exactitude in this respect is not material to the result), there plant
another stake, and continuing in a straight line put in a third. The
stakes must be equal distances apart and as nearly as possible at a
right angle to the first line. Now, carrying in hand a fourth stake,
strike a line inland at right angles to the base and as soon as sighting
over the fourth stake, you can get the fourth and second stakes and the
object on the opposite shore in line your problem is complete. The
distance between No. 4 and No. 3 stakes is the same as that between No.
1 and the opposite bank (Fig. 39).

    [Illustration: FIG. 39. MEASURING INACCESSIBLE DISTANCES.]


     TO SET OUT A RIGHT ANGLE WITH A TAPE.

Measure 40 ft. on the line to which you wish to run at right angles, and
put pegs at A and B (Fig. 40); then, with the end of the tape held
carefully at A, take 80 ft., and have the 80 ft. mark held at B. Take
the 50 ft. mark and pull from A and B until the tape lies straight and
even, you will then have the point C perpendicular to AB. Continue
straight lines by sighting over two sticks in the well-known way.

    [Illustration: FIG. 40.]

    [Illustration: FIG. 41.]

_Another Method._--Stick a pin in each corner of a square board (Fig.
41), and look diagonally across them, first in the direction of the
line to which you wish to run at right angles, and then for the new line
sight across the other two pins.


     A SIMPLE LEVELLING INSTRUMENT.

Fasten a common carpenter’s square in a slit to the top of a stake by
means of a screw, and then tie a plumb-line at the angle so that it may
hang along the short arm, when the plumb-line hangs vertically and
sights may be taken over it. A carpenter’s spirit-level set on an
adjustable stand will do as well. The other arm will then be a level
(Fig. 42).

    [Illustration: FIG. 42. FIG. 43. LEVELLING INSTRUMENTS.]

Another very simple, but effective, device for finding a level line is
by means of a triangle of wood made of half-inch boards from 9 to 12 ft.
long (Fig. 43). To make the legs level, set the triangle up on fairly
level ground, suspend a plummet from the top and mark on the cross-piece
where the line touches it. Then reverse the triangle, end for end,
exactly, and mark the new line the plumb-line makes. Now make a new mark
exactly half way between the two, and when the plumb-line coincides with
this, the two legs are standing on level ground. For short water races
this is a very handy method of laying out a level line.


     TO MEASURE THE HEIGHT OF A STANDING TREE.

Take a stake about your own height, and walking from the butt of the
tree to what you judge to be the height of the timber portion you want,
drive your stake into the ground till the top is level with your eyes;
now lie straight out on your back, placing your feet against the stake,
and sight a point on the tree (see Fig. 44). AB equals BC. If BC is,
say, 40 ft., that will be the height of your “stick of timber.” Thus,
much labour may be saved in felling trees the timber portion of which
may afterwards be found to be too short for your purpose.

    [Illustration: FIG. 44. Measuring Height of a Standing Tree.]


     LEVELLING BY ANEROID BAROMETER (Fig. 45).

This should be used more for ascertaining relatively large differences
in altitudes than for purposes where any great nicety is required. For
hills under 2000 ft., the following rule will give a very close
approximation, and is easily remembered, because 55°, the assumed
temperature, agrees with 55°, the significant figures in the 55,000
factor, while the fractional correction contains _two fours_.

Observe the altitudes and also the temperatures on the Fahrenheit
thermometer at top and bottom respectively, of the hill, and take the
mean between them. Let _B_ represent the mean altitude and _b_ the mean
temperature. Then 55000 × (B-b / B + b) = height of the hill in feet
for the temperature of 55°. Add 1/440 of this result for every degree
the mean temperature exceeds 55°; or subtract as much for every degree
below 55°.

    [Illustration: FIG. 45. ANEROID BAROMETER.]


     TO DETERMINE HEIGHTS OF OBJECTS.

    _By Shadows._

1. Set up vertically a stick of known length, and measure the length of
its shadow upon a horizontal or other plane; measure also the length of
the shadow thrown by the object whose height is required. Then it will
be:--As the length of the stick’s shadow is to the length of the stick
itself, so is the length of the shadow of the object to the object’s
height.


    _By Reflection._

Place a vessel of water upon the ground and recede from it until you see
the top of the object reflected from the surface of the water. Then it
will be:--As your horizontal distance from the point of reflection is to
the height of your eye above the reflecting surface, so is the
horizontal distance of the foot of the object from the vessel to its
altitude above the said surface.


    _Instrumentally._

Read the vertical angle, and multiply its natural tangent by the
distance between instrument and foot of object; the result is the
height.

When much accuracy is not required vertical angles can be measured by
means of a quadrant of simple construction, represented in Fig. 46. The
arc AB is a quadrant, graduated in degrees from B to A; C, the point
from which the plummet P is suspended, being the centre of the quadrant.

    [Illustration: FIG. 46.]

_When_ the sights AC are directed towards any object, S, the degrees in
the arc, BP, are the measure of the angle of elevation, SAD, of the
object.


     TO FIND THE DEPTH OF A SHAFT.

_Rule_:--Square the number of seconds a stone takes to reach the bottom
and multiply by 16.

Thus, if a stone takes 5 seconds to fall to the bottom of a shaft--

    5² = 25; and 25 × 16 = 400 feet, the required depth of shaft.


     DESCRIPTION OF PLAN FOR RE-USING WATER.

Where water is scarce it may be necessary to use it repeatedly. In a
case of this kind in Egypt, the Arab miners have adopted an ingenious
method, which is shown in Fig. 47, and may be adapted to almost any set
of conditions. At _a_ is a sump or water-pit; _b_ is an inclined plane
on which the mineral is washed and whence the water escapes into a tank
_c_; _d_ is a conduit for taking the water back to _a_; _e_ is a conduit
or lever pump for raising the water. A certain amount of filtration
could easily be managed during the passage from _c_ to _a_.

    [Illustration: FIG. 47.]


    COOLING COMPOUND FOR HEATED BEARINGS.

Mercurial ointment mixed with black cylinder oil and applied every
quarter of an hour, or as often as expedient. The following is also
recommended as a good cooling compound for heavy bearings:--Tallow 2
lb., plumbago 6 oz., sugar of lead 4 oz. Melt the tallow with gentle
heat and add the other ingredients, stirring until cold.


    CLEANING GREASY PLUMMER BLOCKS.

When, through carelessness or unpreventable causes, plummer blocks and
other detachable portions of machinery become clogged with sticky
deposits of grease and impurities, a simple mode of cleansing the same
is to take about 1000 parts by weight of boiling water, to which add
about 10 or 15 parts of ordinary washing soda. Keep the water on the
boil and place therein the portions of the machine that are to be
cleaned; this treatment has the effect of quickly loosening all grease,
oil, and dirt, after which the metal is thoroughly washed and dried. The
action of the lye is to form with the grease a soap soluble in water. To
prevent lubricating oil hardening upon the parts of the machinery when
in use, add a third part of kerosene.


     PREVENTING SCALING AND PRIMING IN BOILERS.

Graphite “black-lead” added to the water in a boiler prevents scaling
and priming. My method is to paint the inside of the boiler with a good
coat of graphite mixed with water to the consistency of thin gruel, and
let it stand till dry. It will not be amiss to give a second coat before
getting up steam. Even if slight scaling has already taken place, the
graphite particles will penetrate and the scale come away gradually.


     CLEARING SCALE-STOPPED PIPES.

Where the water contains a large amount of mineral in solution, the
pipes, particularly the small ones, inch to two inch, quickly become
useless because of the rapid deposition of scale. I have seen in West
Australia tons of small pipes thrown on to the scrap heap after a few
months use, because of this difficulty. The treatment now indicated,
which is my own invention, will make such pipes as good as new at small
expense. Have a brick trough a little longer than your pipe. In this put
a fire of wood, charcoal, coke, or a mixture of such fuel. Lay the
pipes, a few at a time, in this. Heat slowly to cherry red. Then with
pinchers suddenly immerse in a second trough of cold water, supporting
one end above the water level. Most of the scale or incrustation will
be violently ejected. With a long pipe, if the heat has not been
regular, some may still adhere. Then usually tapping with a hammer will
detach it. If not, a second heating and immersion will do so, leaving
the interior as clean as when made. It is hardly necessary to add that
’tis best to stand clear of the ends when the explosion takes place.


     AN EXCELLENT ANTI-FRICTION COMPOUND.

For use on cams and stamper shanks, which will be harmless should it
drop into the mortar or stamper boxes, is graphite (black-lead) and soft
soap. When the guides are wooden, the soft soap need not be added;
graphite “black-lead” made into a paste with water will act admirably.


     TO CLEAN BRASS.

Oxalic acid 1 oz., rotten stone 6 oz., powdered gum arabic ½ oz.,
sweet oil 1 oz. Rub on with a piece of rag.


     A SOLVENT FOR RUST.

It is often very difficult, and sometimes impossible, to remove rust
from articles made of iron. Those which are very thickly coated are most
easily cleaned by being immersed in a nearly saturated solution of
chloride of tin. The length of time they remain in this bath is
determined by the thickness of the coating of rust. Generally from
twelve to twenty-four hours is long enough.


     TO PROTECT IRON AND STEEL FROM RUST.

The following method is but little known, although it deserves
preference over many others. Add 7 oz. of quicklime to 1¾ pints of
cold water. Let the mixture stand until the supernatant fluid is
entirely clear. Then pour this off, and mix with it enough olive oil to
form a thick cream, or rather to the consistency of melted and
recongealed butter. Grease the articles of iron or steel with this
compound, and then wrap them up in paper, or if this cannot be done,
apply the mixture somewhat more thickly.


     TO KEEP MACHINERY FROM RUSTING.

Take 1 oz. of camphor, dissolve it in 1 lb. of melted lard; mix with it
(after removing the scum) as much fine graphite as will give it an iron
colour; clean the machinery, and smear it with this mixture. After
twenty-four hours rub off and clean with soft, linen cloth. This mixture
will keep machinery clean for months under ordinary circumstances.


     FIRE-LUTE.

An excellent fire-lute is made of eight parts sharp sand, two parts good
clay, and one part horse-dung; mix and temper like mortar.


     ROPE-SPLICING.

A short splice is made by unlaying the ends of two pieces of rope to a
sufficient length, then interlaying them as in Fig. 48 (upper cut), draw
them close and push the strands of one under the strands of the other
several times as shown in the lower cut.

    [Illustration: FIG. 48.]

This splice makes a thick lump on the rope and is only used for slings,
block-straps, cables, &c.




    APPENDIX

    (_SELECTED DATA FOR MINING MEN_)


    TO FIND LOST PART OF VEIN

Zimmermann’s rule for finding the lost part of a vein on the other side
of a vein, is as follows:--

Lay down upon paper the line of strike of lode and the line of strike of
the fault (cross-course), and by construction ascertain the horizontal
projection of the line of their intersection; from the point where the
cross-course was struck by the lode, draw a line at right angles to the
strike of the former and directed to its opposite wall. Notice on which
side of the line of intersection this perpendicular falls, and after
cutting through the cross-course, seek the “heaved” part of the lode on
that side.

    [Illustration: FIG. 49.]

Thus let AB (Fig. 49) represent, at any depth, the line of strike of a
fault or cross-course dipping east, and CD the line of strike of a lode
dipping south, and we will suppose that in driving from C to D in a
westerly direction, the fault has been met with at D. Knowing the dip of
the lode and that of the fault, it is easy to lay down on any given
scale, A′B′ and C′D′, the lines of strike of the fault and lode
respectively at a certain depth, say 10 fathoms, below AB. The point D″,
where A′B′ and C′D′ meet, is one point of the line of intersection. Join
D and D″, and prolong on both sides. The line MN represents the
horizontal projection of the line of intersection of the two planes. At
D erect DE at right angles and directed towards the opposite wall of the
fault. As DE falls south of MN, the miner, after cutting through the
fault, would drive in a southerly direction and eventually strike the
lode again at F. It will be at once understood that if the miner were
following the lode from _b_ to F, the perpendicular would lie to the
north of the line of intersection, and following the rule, he would
drive in that direction, after cutting through the fault. When several
faults in succession dislocate a lode, very great complications may
arise.


    THE CALCULATION OF ORE RESERVES.[4]

Having finished the survey of a metalliferous mine, the surveyor is
sometimes called upon to calculate the quantity of ore reserves in that
mine. Various methods are employed for this purpose.

    [4] Bennett H. Brough’s “Treatise on Mine Surveying,” sixth
    edition, p. 165.

Indeed, different surveyors will not agree within wide limits as to the
amount of ore reserves in the same mine. Sometimes the amount of ore in
sight will be considered to be a rectangular block, limited by the
outcrop of the vein, the depth of the shaft, and the extreme points of
the levels, diminished by the amount extracted. Other surveyors would
avoid so excessive an amount, and take but one-third of that amount.

The following method is recommended by Mr. J. G. Murphy, an experienced
American mining engineer, as the fairest and most trustworthy:--

Let it be required to calculate the ore reserves in a mine opened up on
a vein with a mean cross section of 6 feet; a cubic foot of the vein
matter in place weighing 150 lb. The ore stopes are generally very
irregular. In this case, however, it may be supposed that the stope
faces are 11 feet apart and 8 feet high. There is an inclined shaft, 10
feet by 6 feet, following the dip of the vein, and six levels, each 7
feet by 6 feet, 100 feet apart. The lengths of the levels are--

       I. 200 feet west 150 feet east.
      II. 160      ”    100      ”
     III. 120      ”    400      ”
      IV. 100 feet west 140 feet east.
       V. 165      ”    180      ”
      VI. 350      ”    150      ”

The longest level west is 350 feet, and the shortest 100 feet.

Assuming the bounding line of the area of available ore to be at a
distance west of the shaft--

   100 + (350-100) = 225 feet
         ---------
             2

If the longest level east is 400 feet, and the shortest 100 feet, the
bounding line in this direction, calculated in a similar way, will be at
a distance of 250 feet from the shaft.

The inclined shaft has opened up the vein for 670 feet. Deducting, say,
15 feet for the irregularity of the surface, the quantity of ore in
sight will be a rectangular block 655 feet deep, 225 + 250, or 475 feet
long and 6 feet wide, that is 1,866,750 cubic feet.

From this quantity, however, must be deducted the quantity of ore
extracted, namely:--

                                                           Cubic Feet.

       Inclined shaft   665 × 10 × 6 =                         39,900
       Level    I.      350 ×  7 × 6 =                         14,700
         ”     II.      260 ×  7 × 6 =                         10,920
         ”    III.      520 ×  7 × 6 =                         21,840
         ”     IV.      240 ×  7 × 6 =                         10,080
         ”      V.      345 ×  7 × 6 =                         14,490
         ”     VI.      500 ×  7 × 6 =                         21,000
         ”      I.    Stoped east (rough estimate)              3,400
         ”      I.      ”    west                               6,500
         ”     II.      ”    west                               7,000
         ”    III.      ”    east                              20,000
         ”     VI.      ”    west                              12,000
                                                              --------
                               Total                          181,530
                               Or in round numbers            182,000

This quantity, deducted from 1,866,750 cubic feet, leave 1,684,750 cubic
feet. Divided by 13½, the number of cubic feet required for a ton, this
gives 124,797 tons of ore in sight.

The quantity of ore discovered in a mine may be estimated from its
specific gravity and the average size of the vein. The specific gravity
of the ore, with that of water taken at 1000 for standard is equal to
the number of ounces in a cubic foot. Great caution is necessary to
determine the proportion of the vein which may be considered solid ore.
A vein 6 feet square and 1 inch thick, contains 3 cubic feet, therefore,
in order to find the number of cubic feet per square fathom of a vein,
it is merely necessary to multiply the thickness in inches by three.

The following example illustrates the method of finding the weight of
any ore per square fathom in a vein. What quantity of galena will be
produced per square fathom from a mineral vein 6 inches in width? One
quarter of the vein consists of galena, the remainder of zinc-blende.
One-twentieth must be allowed for cavities in the vein. The specific
gravity of galena is 7·5, and a cubic foot of water weighs 1000 ounces;
therefore a cubic foot of galena weighs 7500 ounces.

The vein being 6 inches thick, there are 18 cubic feet in a square
fathom. One quarter of that amount, or 4·5 cubic feet, consists of
galena. The weight of galena in ounces is therefore:

    7500 × 4·5 = 33,750 =                    2109·375 lb.
    From this one-twentieth or                105·468 lb.
                                           --------------
    must be deducted, leaving                2003·907 lb.

    or 17 cwt. 3 qr. 15 lb. as the weight of lead ore per square
    fathom.


    ESTIMATING ORE VALUES.

In testing a gold mine with a view to purchase, it should be remembered
that as a rule the intersections of leaders or small veins with the
main ore body are usually the richest portions of the lode. This the
experienced prospector knows, and generally his shafts and cuttings are
made at such points. For the ordinary mining investor, when inspecting
with a view to purchase, these are places to avoid if endeavouring to
form a correct estimate of the value of the ore in bulk. Take samples
across the lode from place to place, break down and bag personally, and
mark bags. Test the rich portions separately and average, estimating
quantity of both.

[Illustration: PLATE VII.--CALIFORNIA PUMP. _To face p._ 171.]


    CALIFORNIA PUMP.

Any handy man or rough bush carpenter can make a California Pump. The
prospectors in the illustration (Plate VII.) are using a home-made
contrivance, which is quite effective for raising water from shallow
depths for “long tom,” or ground sluicing--a wooden frame-work and open
wooden wheel with handle. Over the wheel is run a belt of canvas, say,
six inches wide, with wood stops about a foot apart--a long sloping box,
dipping into the water, up which the stopped belt travels--and you have
a California Pump which, if not a highly scientific device, is at least
very serviceable.


    HYDRAULICS.

    _General Data Regarding Water._

An imperial gallon of water weighs, at 62° F., 10 lbs. avoirdupois. Gallons
× ·1606 = cubic feet. Cubic feet × 6·288 = number of gallons.

Gallons × 277·46 = cubic inches. Cubic inches × 0·003604 = gallons.
Cubic feet of water × 62·28 = number of pounds weight. Pounds of water ×
0·0166 = cubic feet. Gallons of water × 0·004464 = number of tons. Tons
of water × 224 = gallons of water. Cubic feet of water × 0·0278 = number
of tons. Tons of water × 35·97 = cubic feet of water.

A pipe 1 yard long holds approximately (actually, 1·52 per cent. less)
as many pounds of water as the square of its diameter in inches; thus a
6-inch pipe holds approximately 36 lbs. of water in each yard length.


    _Water Pressure._

Ten feet head of water gives a pressure of 4½ lbs. per square inch
approximately.

If H = head of water in feet, P = pounds pressure per square inch:

    H = P × 2·311      P = H × ·4326

_Horse-power required to Pump Water._--One h.-p. indicated will raise
about 3000 gallons of water per hour 50 feet high.

To pump 1 gallon of water per minute against a pressure of 4 lb. per
square inch, requires:

    p × ·0007 H.-P.


    BORING.

Rock is bored with jumpers of 10 lb. to 18 lb., used alone, or with
boring bars and hammer. The former are more effective, but can only be
used perpendicularly, or nearly so, and with rock of moderate hardness;
they require more skill.

    18 lb.  hammers are used for    3 in.        boring bars.
    16 lb.     ”           ”        2½ in.            ”
    14 lb.     ”           ”        2 & 1¾ in.        ”
    5-7 lb.    ”           ”        1 in.             ”

The boring bars may be made of 1-1/8-inch bar iron of various lengths,
with steel bits up to 3 inches. A bit should bore from 18 feet to 24
feet with each steeling, and requires to be sharpened once for every
foot bored.

    3 men with a 3-inch bar should bore  4 feet.
    3  ”    ”    2½   ”       ”     ”    6   ”
    3  ”    ”    2    ”       ”     ”    8   ”
    3  ”    ”    1¾   ”       ”     ”   12   ”
    2  ”    ”    1    ”       ”     ”    8   ”
       per day of 10 hours in hard granite.


    POWER, ETC., REQUIRED TO WORK ROCK DRILLS.

  +-----+----------+----------+--------+---------------+
  |     | Diameter | Diameter |        |   No. of      |
  |H.-P.| of Air   | of Steam | Stroke.| 3-inch Drills |
  |     | Cylinder.| Cylinder.|        |   driven.     |
  +-----+----------+----------+--------+---------------|
  |     |  Inches. |  Inches. | Inches.|               |
  |   6 |    8     |     8½   |   12   |      1        |
  |  10 |   10     |    10½   |   16   |      2        |
  |  14 |   12     |    12¼   |   22   |      3        |
  |  16 |   13     |    13    |   24   |      4        |
  |  20 |   14½    |    14½   |   28   |      5        |
  |  30 |   17½    |    17½   |   36   |      8        |
  |  40 |   20     |    20    |   36   |     11        |
  |  60 |   22     |    24    |   60   |     15        |
  +-----+----------+----------+--------+---------------+


    POWER REQUIRED TO WORK DOUBLE STEAM AND AIR CYLINDERS.

  +------+----------+------------+---------+---------------+
  |      | Diameter | Diameter of|         | No. of 3-inch |
  | H.-P.| of Air   | Steam      | Stroke. | Rock Drills   |
  |      | Cylinder.| Cylinder.  |         | driven.       |
  +------+----------+------------+---------+---------------+
  |      | Inches.  |   Inches.  |  Inches.|               |
  |  28  |  12      |      12    |    22   |       7       |
  |  32  |  13      |      13    |    24   |       8       |
  |  40  |  14½     |      14½   |    28   |      10       |
  |  60  |  17½     |      17½   |    36   |      15       |
  |  80  |  20      |      20    |    36   |      22       |
  | 120  |  22      |      24    |    60   |      30       |
  +------+----------+------------+---------+---------------+


    DURABILITY OF ROPES.

The average duration of flat, wire ropes is usually taken at one year,
and that of round ropes at half a year.


    DIAMOND DRILLING.

This drill is applicable to sinking a borehole for prospecting for
minerals or water, shafts, &c., or blasting under water.

It consists of a circular row of “carbonados,” a species of diamond, set
in a circular steel ring. This is attached to a hollow steel tube which
is kept rotating at about 250 revolutions per minute, pressed forward by
a force varying from 400 to 800 lb. according to the nature of the rock.
Water is supplied through the tube which washes out the _débris_ and
cools the diamonds.

Granite and the hardest limestones are penetrated at the rate of 2 to 3
inches per minute, sandstones 4 inches, quartz 1 inch.

The diamond drill is not effective in soft strata such as clay, sand,
and alluvial deposits.

Boreholes have been made at the following rates:

  _In Ironstone formation_:

      A depth of 902 feet in 54 working days.
                 641      ”  48      ”
                 434      ”  54      ”
                 640      ”  60      ”
      Or an average of 12 feet a day.

  _In Coal measures_:

      A depth of 1008 feet in 146 days
                  802     ”   168   ”
                  700     ”    48   ”
                  558     ”    42   ”
      Or an average of 7½ feet a day.


     TIMBER.

    =To find Solidity of Round Timber.=

_When all dimensions are in feet_: Length × (¼ mean girth)² = cubic
feet.

_When length in feet_, _girth in inches_: Length × (¼ mean girth) ÷
144 = cubic feet.

_When all dimensions are in inches_: Length × (¼ mean girth)² ÷ 1728
= cubic feet.

    =To find Solidity of Square Timber.=

_When all dimensions are in feet_: Length × breadth × depth = cubic
feet.

_When one dimension is in inches_: Length × breadth × depth ÷ 12 = cubic
feet.

_When two dimensions are in inches_: Length × breadth × depth ÷ 144 =
cubic feet.

    For board measure, depth always equal 1 inch.

To find surface in square feet, proceed as per rules for solidity of
square timber.


     LAYING OUT OF AREAS.

1. _In Squares._--Extract the square root of the desired content,
reduced to square chains (ten square chains equal one acre). The result
will be the length of the required side in chains.

Thus if we wish to find the side of a square block containing 25 acres,
we first reduce the acres to square chains: 25 × 10 = 250, the square
root of which is 15·81, or 15 chains 81 links; the side required.

By reference to the tables of square roots on page 189, the required
sides of square block for a large number of acres can be read off at
once.

_One acre_ laid out as a square must have its side made 316¼ links,
or 208-71/100 feet, or 69-57/100 yards, 70 paces being a near
approximation.

2. _In Rectangles._--Divide the content by the length or breadth,
according to which factor is known, and the result will be the required
side.

Thus 5 acres, or 50 square chains, if 10 chains long, will require to be
5 chains wide.

If the content only is given, and the length is to be a certain number
of times the breadth, the content in square chains divided by the ratio
of the length to the breadth, and the square root of the quotient, will
give the length of the shorter side. Thus, if we wish to lay out 72
acres as a rectangle twice as long as broad: 72 acres = 720 square
chains, divided by 2, the ratio given, = 360, the square root of which
is 18·97 chains, the length of the shorter side. The length of the other
side is therefore 18·97 × 2 = 37·94 chains, or 3794 links.


     MENSURATION.

=TO FIND THE AREA OF A TRIANGLE WHEN THE BASE AND PERPENDICULAR HEIGHT
ARE GIVEN=: Multiply the base by half the height, or _vice versâ_.

=TO FIND THE AREA OF A TRIANGLE WHEN THE THREE SIDES ARE GIVEN=: Take half
the sum of the sides, subtract each severally from this sum, then
multiply this and the three remainders together, and take the square
root for the area.

=TO FIND THE AREA OF A RECTANGULAR FIGURE=: Multiply the length by the
breadth, the product will be the area.

=TO FIND THE AREA OF A TRAPEZOID=: Multiply half the sum of the two
parallel sides by the distance between them.

=TO FIND THE AREA OF A PARALLELOGRAM WHOSE ANGLES ARE NOT RIGHT ANGLES=:
Multiply the length of any one of the sides by the perpendicular.

=TO FIND THE AREA OF A TRAPEZIUM=: Divide it into two triangles and find
the areas of the latter by the first rule.

=TO FIND THE AREA OF AN IRREGULAR POLYGON=: Divide the polygon into
triangles and find the area of the latter.

=TO FIND THE AREA OF AN IRREGULAR FIGURE=: Draw the figure on fine
cardboard or thin sheet metal, cut the same carefully out and weigh with
an accurate balance. Then this weight, compared with the weight of a
piece of the cardboard or metal of a definite size, say one square inch,
gives at once the area required.


     MINE SURVEYING PROBLEMS.

It would be futile to profess, in the limits of a small work of this
kind, to instruct the beginner fully in the principles and practice of
mine surveying, especially as the most elaborate treatise can only be of
service when some actual practical experience and knowledge of
instruments have been obtained.

For an exhaustive and well-arranged work on the subject, Brough’s
“Treatise on Mine Surveying” can be strongly recommended, and should be
carefully studied by all wishing to learn the best methods of
accomplishing the accurate results that any mine-surveying worth the
name demands.

The following methods of connecting underground and surface work are
therefore addressed to such as are thoroughly acquainted with a dial and
the method of traversing.

1. =TO FIND WHERE A SHAFT SHOULD BE SUNK TO CONNECT WITH ANY PART OF THE
UNDERGROUND WORKINGS.=

Should the mine be one opened by an adit, there is no difficulty in
doing this, as the dial can be set up at the mouth and a sight taken to
a light; this can then, by means of the vertical arc, be prolonged up
the hill, and the remaining bearings and distances are then easily laid
down to the desired point. When a starting-point has been obtained, the
chief difficulty in these cases has been overcome. If a single shaft is
the only connection to the underground workings, the magnetic bearing of
the first line at bottom must first be carefully ascertained, and the
position of the first station brought to the surface by means of a
plumb-line, made of copper wire preferably, the plummet being put into a
dish of water to steady it. The dial is then set exactly over the end of
the line at the surface, and the first bearing and distance laid off.

Should it be impossible to set the instrument over the point at surface,
a spot must be found by trial outside the shaft which is in the correct
course. The dial is set up in the supposed direction of the line and
repeated sights taken to the first point till the instrument and it are
exactly in the required line, when the length of the first line can be
measured along it, and the new lines proceeded with.

As local attraction frequently affects the needle at the bottom of the
shaft, and so vitiates the surface survey that depends on its swinging
the same at both points, a method of dispensing with the needle must be
resorted to. This is the suspension of two plumb-lines from opposite
sides of the shaft, the plummets hanging exactly over as much of the
first underground line as the width of the shaft will allow.

The two plummet lines at surface then give the direction, and by trial
the dial must be put exactly in line with them in order to prolong it
correctly.

If there are two or more shafts sunk on the workings, it will be an easy
matter to ascertain if the needle can be depended on for laying out any
further surface work, as the underground survey connecting the shafts
can be laid down on the surface, or the direct bearing and distance
calculated, when its correctness is tested by the terminating point of
the survey.

2. =TO FIND DEPTH OF SHAFT AT ANY POINT, TO CUT A VEIN WHOSE DIP IS KNOWN.=

RULE:--Multiply natural tangent of angle of dip C (Fig. 50.) by the
distance from outcrop to proposed shaft AC. The result is the depth
required, AB.

=_By Protractor and Scale._=--Rule on paper a line AC of the required
distance, then at C set off the angle of dip and draw AB at right
angles to AC. Then scale off AB = depth of shafts.

    [Illustration: FIG. 50.]

3. =GIVEN DEPTH OF SHAFT AND ANGLE OF DIP TO FIND WHERE IT OUTCROPS.=
--Then AC = AB × natural tangent of angle ABC. Or by scale and
protractor by inspection.

4. =GIVEN DEPTH OF SHAFT AB AND DIP OF VEIN ANGLE CB TO FIND DISTANCE BC
BETWEEN BOTTOM OF SHAFT AND OUTCROP.=--BC = AC × natural sine ACB. Or by
scale and protractor by inspection.


     RAINFALL.

One inch of rain = 22,680 gallons, or 102·35 tons of water per acre.


     NOTES ON BELTING.

_Co-efficient_ of friction between ordinary leather belting and
cast-iron pulleys or drums = ·423. Ultimate strength of ordinary leather
belting = 3086 lb. per square inch. Belts vary from ³/₁₆ in. to ¼ in.
thick, average ⁷/₃₂ in.

_Power of Single Leather Belts._

To calculate the power of single leather belts, the following formula
may be used: Let HP = actual horse-power. W = width of belt. F = driving
force. T = working tension from 70 to 150 lb. V = velocity of belt in
feet per minute.

Then F = (W × T)/2. HP = V × F/33,000. W = 33,000 × HP/F × V.

=EXAMPLE:=--A 10-inch belt running 2500 feet per minute, what horse-power
will it transmit? Assuming the working tension to be 100 lb.,

F = (10 × 100)/2 = 500. HP = (25,000 × 500)/33,000 = 378 horse-power.

Nystrom gives this rule:--HP = (V × F)/550. V = velocity of belt in feet
per second. F = force in pounds transmitted by belt.

The first rule gives good practical results where there is no great
inequality in the diameter of the pulleys.

_Double Belts_ transmit 1½ times as much as single belts.

_Splicing Belts._

                  +----+-----+-----+-------+--------+------------+
  Width of Belts. | 1  |  2  |  3  | 3 to 6| 6 to 8 | above 8 in.|
  Lap in inches . | 2  |  4½ |  5½ |   6   |     8  |    10      |
                  +----+-----+-----+-------+--------+------------+

_Rules for Double Leather Belting._

A = covered area of driven pulley in square inches.

V = speed of belt in feet per minute.

H = indicated horse-power.

W = width in inches.

H = AV/66,000 A = (66,000 H)/V. W = A/L, where L = length of belt on
driven pulley in inches.

Another authority simply says H = {70 to 80} × (WV)/33,000

And a third says W = (36,000 H)/(6VL), where L is here in feet.

Evan Leigh’s rule is W = (66,000 × IHP)/(L × V).

L = length of arc of contact upon smaller pulley in inches.

V = velocity of rim in feet per minute.

_A belt_ transmits its motion solely through frictional contact with the
surfaces of the pulley. The lower side of the belt should be made the
driving side when possible, as the arc of contact is thereby increased
by the sagging of the following side. Increase of power will be obtained
by increasing the size of pulleys, the same ratio being retained. Wide
belts are less effective per unit of sectional area than narrow belts.
Long belts are more effective than short ones. The proportion between
the diameters of two pulleys working together should not exceed six to
one. Convexity of pulleys to receive belt = ½ inch per foot wide. The
width of pulley should equal 1·2 times width of belt.


_Speed of Belts._

Belts have been employed running over 5000 feet per minute. Nothing,
however, is gained by running belts much over 4000 feet per minute.
About 3500 feet per minute for main belts agrees with good practice;
lathe belts from 1500 to 2000 feet per minute. The life of a belt may be
prolonged and its driving powers increased by keeping it in good working
order. To ensure this it should be dressed on the back with castor oil
every few weeks, more or less according the dryness of the _atmosphere_
in which it works.


     WEIGHT AND BULK OF MATERIALS.

The weight of a cubic foot of any material is its specific gravity
multiplied by 62·425, or the weight of a cubic foot of water in pounds.
To find the specific gravity of a stone, divide its weight in air by
loss of weight in water of temperature of 60° F. = specific gravity.

Thus:

    Quartz crystal weighs in air               293·7 grains.
       ”      ”       ”      water             180·1    ”
                                               -----
                         Loss in weight        113·6    ”

Then:

    293·7 / 113·6 = 2·59 = Specific gravity of quartz.

One ton of quartz when solid occupies 13 cubic feet, but when broken,
about 20. Rocks when solid, as compared to the same when broken, usually
increase in volume in the ratio of 1 to 1·5 or 1 to 1·18, the increase
depending on size and form of fragments.

A dwt. of gold in a cwt. of ore = 1 oz. of gold per ton of ore.

For approximate calculation a grain of gold = two pence, and a dwt.,
four shillings.

In the following table of the chemical elements the standard of sp. gr.
is hydrogen for the gaseous elements (hydrogen, oxygen, &c.) and water
for the others.


    THE CHEMICAL ELEMENTS, THEIR SYMBOLS, EQUIVALENTS, AND SPECIFIC
    GRAVITIES.

    +----------------------+---------+--------+-----------+
    |      Name.           | Symbol. | Atomic | Specific  |
    |                      |         | Weight.| Gravity.  |
    +----------------------+---------+--------+-----------+
    | Aluminium            |     Al  |   27·5 |    2·56   |
    | Antimony             |     Sb  |  122·0 |    6·70   |
    | Arsenic              |     As  |   75·0 |    5·7    |
    | Barium               |     Ba  |  137·0 |    4·00   |
    | Bismuth              |     Bi  |  210·0 |    9·7    |
    | Boron                |     B   |   11·0 |    2·63   |
    | Bromine              |     Br  |   80·0 |    5·54   |
    | Cadmium              |     Cd  |  112·0 |    8·60   |
    | Caesium              |     Cs  |  133·0 |    1·88   |
    | Calcium              |     Ca  |   40·0 |    1·58   |
    | Carbon               |     C   |   12·0 |    3·50   |
    | Cerium               |     Ce  |   92·0 |    6·68   |
    | Chlorine             |     Cl  |   35·5 |    2·45   |
    | Chromium             |     Cr  |   52·5 |    6·81   |
    | Cobalt               |     Co  |   58·8 |    7·7    |
    | Columbium            |     Cb  |  184·8 |    6·00   |
    | Copper               |     Cu  |   63·5 |    8·96   |
    | Didymium             |     Di  |   96·0 |    6·54   |
    | Erbium               |     E   |  112·6 |     --    |
    | Fluorine             |     F   |   19·0 |    1·32   |
    | Gallium              |     Ga  |   69·9 |    5·9    |
    | Glucinum             |     Gl  |    9·5 |    2·1    |
    | Gold (Aurum)         |     Au  |  196·7 |   19·3    |
    | Hydrogen             |     H   |    1·0 |    0·069  |
    | Indium               |     In  |  113·4 |    7·4    |
    | Iodine               |     I   |  127·0 |    4·94   |
    | Iridium              |     Ir  |  198·0 |   21·15   |
    | Iron (Ferrum)        |     Fe  |   56·0 |    7·79   |
    | Lanthanum            |     La  |   90·2 |   11·37   |
    | Lead (Plumbum)       |     Pb  |  207·0 |   11·44   |
    | Lithium              |     Li  |    7·0 |    0·59   |
    | Magnesium            |     Mg  |   24·0 |    1·75   |
    | Manganese            |     Mn  |   55·0 |    8·01   |
    | Mercury (Hydrargyrum)|     Hg  |  200·0 |   13·59   |
    | Molybdenum           |     Mb  |   96·0 |    8·60   |
    | Nickel               |     Ni  |   58·8 |    8·60   |
    | Niobium              |     Nb  |   94·0 |    6·27   |
    | Nitrogen             |     N   |   14·0 |    0·972  |
    | Osmium               |     Os  |  199·0 |   21·40   |
    | Oxygen               |     O   |   16·0 |    1·105  |
    | Palladium            |     Pd  |  106·5 |   11·60   |
    | Phosphorus           |     P   |   31·0 |    1·83   |
    | Platinum             |     Pt  |  197·4 |   21·53   |
    | Potassium (Kalium)   |     K   |   39·0 |    0·865  |
    | Rhodium              |     Rh  |  104·3 |   12·1    |
    | Rubidium             |     Ru  |  104·4 |   11·4    |
    | Selenium             |     Se  |   79·5 |    4·78   |
    | Silicon              |     Si  |   28·0 |    2·49   |
    | Silver (Argentum)    |     Ag  |  108·0 |   10·5    |
    | Sodium (Natrium)     |     Na  |   23·0 |    0·972  |
    | Strontium            |     Sr  |   87·6 |    2·54   |
    | Sulphur              |     S   |   32·0 |    2·05   |
    | Tantalium            |     Ta  |  182·0 |   10·78   |
    | Tellurium            |     Te  |  129·0 |    6·02   |
    | Thallium             |     Tl  |  204·0 |   11·91   |
    | Thorium              |     Th  |  115·7 |    7·8    |
    | Tin (Stannum)        |     Sn  |  118·0 |    7·28   |
    | Titanium             |     Ti  |   50·0 |    4·3    |
    | Tungsten (Wolfram)   |     W   |  184·0 |    7·5    |
    | Uranium              |     U   |  120·0 |   18·4    |
    | Vanadium             |     V   |   51·3 |    5·50   |
    | Yttrium              |     Y   |   61·7 |     --    |
    | Zinc                 |     Zn  |   65·0 |    7·14   |
    | Zirconium            |     Zr  |   89·5 |    4·15   |
    +----------------------+---------+--------+-----------+

The figures indicating the proportions by weight in which the elements
unite with one another are called the combining or atomic weights,
because they represent the relative weights of the atoms of the
different elements. Since hydrogen is the lightest element, it is taken
as the standard, and its combining or atomic weight = 1.

_To find the proportional parts by weight of the elements of any
substance whose chemical formula is known_:

RULE.--Multiply together the equivalent and the exponent of each element
of the compound; the product will be the proportion by weight of that
element in the substance.

_Example_:--Find the proportional weights of the elements of Alcohol
C₂H₆O.

    Carbon C₂     =  equivalent 12  ×  exponent      2 = 24
    Hydrogen H₆   =      ”       1  ×      ”         6 =  6
    Oxygen O      =      ”      16  ×      ”         1 = 16

Of every 46 lb. of Alcohol, 6 lb. will be H; 16, O; 24, C.

To find the proportions by _volume_, divide by the specific gravity.


       COMMON NAMES OF CHEMICAL SUBSTANCES.

  _Common Names._                _Chemical Names._

  Aqua fortis                    Nitric acid.
  Aqua regia                     Nitro-hydrochloric acid.

  Blue vitriol                   Sulphate of copper.

  Cream of tartar                Bi-tartrate of potassium.
  Calomel                        Chloride of mercury.
  Chalk                          Carbonate of calcium.
  Caustic potash                 Hydrate of potassium
  Chloroform                     Chloride of formyl.
  Common salt                    Chloride of sodium.
  Copperas, or green vitriol     Sulphate of iron.
  Corrosive sublimate            Bi-chloride of mercury.

  Dry alum                       Sulphate of aluminium and potassium.

  Epsom salts                    Sulphate of magnesium.
  Ethiops mineral                Black sulphide of mercury.

  Galena                         Sulphide of lead.
  Glauber’s salt                 Sulphate of sodium.
  Glucose                        Grape sugar.

  Iron pyrites                   Bi-sulphide of iron.

  Jeweller’s putty               Oxide of tin.

  King’s yellow                  Sulphide of arsenic.

  Laughing gas                   Protoxide of nitrogen.
  Lime                           Oxide of calcium.
  Lunar caustic                  Nitrate of silver.

  Mosaic gold                    Bi-sulphide of tin.
  Muriate of lime                Chloride of calcium.

  Nitre, or saltpetre            Nitrate of potash.

  Oil of vitriol                 Sulphuric acid.

  Potash                         Oxide of potassium.

  Realgar                        Sulphide of arsenic.
  Red lead                       Oxide of lead.
  Rust of iron                   Oxide of iron.

  Sal ammoniac                   Chloride of ammonia.
  Salt of tartar                 Carbonate of potassium.
  Slacked lime                   Hydrate of calcium.
  Soda                           Oxide of sodium.
  Spirits of hartshorn           Ammonia.
  Spirits of salt                Hydrochloric acid.
  Stucco, or plaster of Paris    Sulphate of lime.
  Sugar of lead                  Acetate of lead.

  Verdigris                      Basic acetate of copper.
  Vermilion                      Sulphide of mercury.
  Vinegar                        Acetic acid (diluted).
  Volatile alkali                Ammonia.

  Water                          Oxide of hydrogen.
  White precipitate              Ammoniated mercury.
  White vitriol                  Sulphate of zinc.


     THERMOMETER.

The following are the formulæ for the conversion of degrees of one scale
to those of another:--

(Centigrade° × 9 /5)+ 32 = Fahr.° |(Fahr.° - 32 × 4) / 9 = Réaumur°.
                                  |
(Réaumur°    × 9)/4 + 32 = Fahr.° |(Centigrade° × 4) / 5 = Réaumur°.
                                  |
(Fahr.°   32 × 5)/9      = Cent.° |(Réaumur°    × 5) / 4 = Centigrade°.


     FREEZING, FUSING, AND BOILING POINTS.

  +------------------------------+---------+------------+-------------+
  |                              |         |            |             |
  |     Substances.              | Réaumur.| Centigrade.| Fahrenheit. |
  |                              |         |            |             |
  +------------------------------+---------+------------+-------------+
  |                              |         |            |             |
  |Bromine     freezes at        | -17·6° =|    -22°   =|    -7·6°    |
  |Oil, Anise      ”             |    8   =|     10    =|    50       |
  |Oil, Olive      ”             |    8   =|     10    =|    50       |
  |Oil, Rose       ”             |   12   =|     15    =|    60       |
  |Quicksilver     ”             | -31·5  =|    -39·4  =|   -39°      |
  |Water           ”             |    0   =|      0    =|    32°      |
  |Bismuth metal fuses at        |  211   =|    264    =|   507°      |
  |Copper          ”             |  963   =|   1204    =|  2200       |
  |Gold            ”             |  963   =|   1204    =|  2200       |
  |Iodine          ”             |   95·6 =|    107°   =|   224·6°    |
  |Iron            ”             | 1230   =|   1538    =|  2800       |
  |Lead            ”             |  26    =|    325    =|   617       |
  |Potassium       ”             |   50   =|     62·5° =|   144·5°    |
  |Silver          ”             |  530   =|    537·70 =|  1000       |
  |Sodium          ”             |   76·5°=|     95·6  =|   204°      |
  |Steel melts at a lower        |         |            |             |
  | temperature than malleable   |         |            |             |
  | iron                         |   --    |     --     |    --       |
  |Sulphur fuses at              |   54   =|    120    =|   248°      |
  |Tin           ”               |  189·6°=|    237    =|   459°      |
  |Zinc          ”               |  329·6°=|    412    =|   773°      |
  |Alcohol boils at              |   59·5°=|     74·4  =|   173·1     |
  |Bromine       ”               |   46·4 =|     58    =|   136       |
  |Ether         ”               |   28·4 =|     35·5  =|    96       |
  |Iodine        ”               |  140   =|    175    =|   347       |
  |Quicksilver   ”               |  288   =|    360    =|   680       |
  |Water         ”               |   80   =|    100    =|   212       |
  +------------------------------+---------+------------+-------------+


     HEAT VALUES OF FUELS.

Pounds of water evaporated by 1 lb. of fuel as follows:--

    Straw                 1·9          |     Coke or Charcoal   6·4
    Wood                  3·1          |     Coal               7·9
    Peat                  3·8          |     Petroleum         14·6


     SIGNS AND SYMBOLS USED IN EXPRESSING FORMULAS.

= Sign of equality, denoting that quantities so connected are equal to
one another; thus, 3 feet = 1 yard.

+ Sign of addition, signifying _plus_ or more; thus, 4 + 3 = 7.

-Sign of subtraction, signifying _minus_ or less; thus, 4-3 = 1.

× Sign of multiplication, signifying multiplied by or into; thus, 4 × 3
= 12.

÷ Sign of division, signifying divided by; thus, 4 ÷ 2 = 2.

{} () [] Brackets, denoting that the quantities between them are to be
treated as one quantity; thus, 5 {3(4 + 2)-6(3-2)} = 5 (18-6) = 60.

Letters are used to shorten or simplify a formula. Supposing we wish to
express length × breadth × depth, we may put the initial letters only,
thus, _l_ × _b_ × _d_, or, as is usual when algebraical symbols are
employed, leave out the sign × between the factors, and write the
formula _lbd_.

When division is to be expressed in simple form, the divisor is written
under the dividend; thus (_x_ + _y_) ÷ _z_ = (_x_ + _y_)
                                               ________
                                                  _z_

° ’ ” are signs used to express certain angles in degrees, minutes, and
seconds; thus 25 degrees 4 minutes 21 seconds would be expressed 25° 4’
21”.

√ This sign is called the radical sign, and placed before a
quantity indicates that some root of it is to be taken, and a small
figure placed over the sign, called the exponent of the root, shows
what root is to be extracted.

    Thus ²√ _a_ or √ _a_ means the square root of _a_
             ∛ _a_            ”    cube    ”
             ∜ _a_            ”    fourth  ”

ρ This sign is used to denote the force of gravity at any given latitude.

π The Greek letter pi is invariably used to denote 3·14159, that is,
the ratio borne by the diameter of a circle to its circumference.

When the figure 2 is affixed to any number, as diameter² or 12², the
number is to be squared, as 12 × 12 = 144, the square; and with ³
affixed, the number is to be cubed--_i.e._, multiplied twice by itself,
as 6³ = 6 × 6 × 6 = 316, the cube of 6.


    =ENGLISH WEIGHTS AND MEASURES.=


    MEASURES OF LENGTH.

   12 lines        = 1 inch.    |    8 furlongs    }
   12 inches       = 1 foot.    | 1760 yards       }  = 1 statute mile.
    3 feet         = 1 yard.    | 5280 feet        }
    6 feet         = 1 fathom.  | 6086 feet           = 1 naut. mile.
   16½ feet        = 1 pole.    |    7·92 inches      = 1 link.
  220 yards        = 1 furlong. |  100 links       }
                                    66  feet       }  = 1 chain.
                                    22 yards       }


    SQUARE MEASURE.

    144 sq. inches   = 1 sq.foot.  | 10 sq. chains    = 1 acre.
      9 sq. feet     = 1 sq.yard.  |  1 hectare       = 2·471 acres.
     30¼ sq.yards}= 1 sq.rod       |640 acres         = 1 sq. mile.
    272¼ feet    }     or pole.    | 30 sq. acres     = 1 yard of land.
     40 rods         = 1 sq.rood.  |Sq. ins. × 0·007  = {square foot
      4 roods       }              |                    { nearly.
    160 rods        }              |Sq. yds. × 0·00021= acres nearly.
   4840 yards       }= 1 acre.     |113·0977 sq. ins. = 1 circular foot.
  43560 feet        }              |183·46 circular ins.= 1 square foot.


    SOLID OR CUBIC MEASURE.

 1728 cubic inches          = 1 cubic foot.  |
   27 cubic feet            = 1 cubic yard.  | 128 cub. ft.  = {1 cord
   40 cub. ft. of rough, or   {              |    of timber    {of wood.
   50 cub. ft. of hwn. tmbr.= {1 ton or load.|


    AVOIRDUPOIS WEIGHT.

    16 drachms   = 1 ounce.           |    20 cwt         = 1 ton.
    16 ounces    = 1 lb.              | lbs. × 0·009      = cwt. nearly.
    14 lb.       = 1 stone.           | lbs. × 0·00045    = tons.
    28 lb.       = 1 qr. cwt.         |  7000 grains      = 1 lb. avdp.
   112 lb.       = 1 cwt.             |   437½ grains  = 1 oz.


    TROY WEIGHT.

   24 grains     = 1 dwt.             |  5760 grains       = 1 lb. troy.
   20 dwt.       = 1 ounce.           |    480 grains      = 1 oz.   ”
   12 oz.        = 1 lb.              |


    APOTHECARIES’ FLUID MEASURE.

Gallon (C) = 8 pints (O); 1 pint = 20 fluid ounces (oz. weight of water).

Ounce (f ℥) = 8 drachms (f ʒ) = 480 minims (♏) = 720 drops (gtt.).

One wine glass = 4 tablespoonfuls = 16 tablespoonfuls = 2 ounces.

_Symbols._--f. or fl. fluid; s.s. one half; a.a. for each. Thus f℥ss. ½
a fluid ounce.

Apothecaries’ weight, formerly used for dispensing medicines, superseded
in 1864. 20 grains = 1 scruple; 3 scruples = 1 drachm; 8 drachms = 1
ounce; 12 ounces = 1 lb. (troy).


    LIQUID MEASURE.
                                     Cubic in. nearly.
  4 gills     =    1 pint        =        34¾
  2 pints     =    1 quart       =        69⅓
  4 quarts    =    1 gallon      =       277·123


    FRENCH WEIGHTS AND MEASURES.

    WEIGHTS.

 Gramme                                       15·432349 grams troy.
 Décagramme (= 10 grammes)                     5·6438 drachms av.
 Hectogramme(= 100 grammes)                    3·527 oz. av.
 Kilogramme (= 1000 grammes)                   2·204621 lbs. av., or
                                                   2·679227 lbs. troy.
 Quintal    (= 100 kilogrammes)              220·462 lbs. av.
 Tonne      (= 1000 kilogrammes)            2204·621 lbs. av.
 Decigramme (= 1/10th of a gramme)             1·5432 grain.
 Centigramme(= 1/100th of a gramme)            0·15432 grain.
 Milligramme(= 1/1000th of a gramme )          0·015432 grain.


    LINEAL MEASURE.

 Mètre                                         3·2808992 feet.
 Décamètre (= 10 mètres)                      32·808992 feet.
 Hectomètre(= 100 mètres)                    328·08992 feet.
 Kilomètre (= 1000 mètres)                  1093·633 yards.
 Myriamètre(= 10,000 mètres)                   6·2138 miles.
 Decimètre (= 1/10th of a mètre)               3·937079 inches.
 Centimètre(= 1/100th of a mètre)              0·39371 inch.
 Millimètre(= 1/1000th of a mètre)             0·03937 inch.


    SUPERFICIAL MEASURE

  Centiare (= 1 square mètre)                  1·196033 square yard.
  Are(= 100 square mètres)                     0·098845 rood.
  Hectare (= 10,000 square mètres)             2·471143 acres.


    MEASURES OF CAPACITY.

  Litre      (= 1 décimétre cube)    1·760773 pint(61·027 cubic inches).
  Décalitre  (= 10 litres)           2·2009668 gallons.
  Hectolitre (= 100 litres)         22·009668    ”
  Kilolitre  (= 1000 litres)       220·09668     ”
  Décilitre  (= 1/10th of a litre)    ·17607 pint.
  Centilitre (= 1/100th of a litre)   ·017607 pint.


    SOLID MEASURE.

  Stère      (= 1 cubic mètre)        1·31 cubic yard.
  Décastère  (= 10 stères)           13 cubic yards, 2 feet, 21 inches.
  Décistère  (= 1/10th of a stère)    3 cubic feet, 918·7 cubic inches.


    FRESH AND SALT WATER COMPARED.

                                    FRESH.                 SALT.
  1 cubic foot at 40° weighs      62·425 lbs.             64 lbs.
  1 cubic inch at 40° weighs        ·036,126 lbs.           ·037,037 lbs.
  1 cubic foot at 40° equals       6·242 gallons           6·2 gallons.
  1 ton equals                    35·943 cubic ft.        35 cubic ft.
  1 ton contains at 62°          224 gallons             217 gallons.


    VELOCITY OF FALLING FLUIDS.

Falling fluids are governed by the same laws as falling bodies.

Fluid falls 1 foot in a ¼ of a second, 4 feet in ½ of a second, 9 feet
in ¾ of a second, and so on.

The velocity of a fluid, flowing through an aperture in the side of a
reservoir, is the same that a heavy body would acquire by falling from a
height equal to that between the surface of the fluid and the middle of
the opening.

The velocity of a fluid flowing out of an aperture is as the square
root of the height of the head of the fluid. The theoretical velocity,
therefore, in feet per second is as the square root of the product of
the space fallen through in feet and 64·333; consequently, for 1 foot
it is [Sqrt]64·333 = 8·02 feet. The mean velocity is about 5·4 feet, or
0·673.


    PRESSURE OF WATER AT DIFFERENT HEADS.

H. = head in feet. P. = pressure in lbs. per sq. foot. p. = pressure in
lbs. per sq. inch.

  +------+--------+-------+------+--------+----------+
  |   H. |   P.   |   p.  |  H.  |   P.   |    p.    |
  +------+--------+-------+------+--------+----------+
  | 1    |   62·4 | ·4333 |    9 |  561·6 |  3·9     |
  | 1·25 |   78   | ·5416 |   10 |  624   |  4·3333  |
  | 1·5  |   93·6 | ·65   |   20 | 1248   |  8·6666  |
  | 1·75 |  109·2 | ·7538 |   30 | 1872   | 13       |
  | 2    |  124·8 | ·8666 |   40 | 2496   | 17·3333  |
  | 3    |  187·2 |1·3    |   50 | 3120   | 21·6666  |
  | 4    |  249·6 |1·7333 |   60 | 3744   | 26       |
  | 5    |  312   |2·1666 |   70 | 4368   | 30·3333  |
  | 6    |  374·4 |2·6    |   80 | 4992   | 34·6666  |
  | 7    |  436·8 |3·0333 |   90 | 5616   | 39       |
  | 8    |  499·2 |3·4666 |      |        |          |
  +------+--------+-------+------+--------+----------+


    TO FIND THE CONTENTS OF A TANK.

To find the number of gallons contained in a tank, multiply the length,
width, and depth together, in feet. This gives the contents in cubic
feet; multiply by 6·24, and the result is the number of gallons
contained. If the dimensions are in inches, use ·003607 in place of
6·24.


    SIZES AND WEIGHT OF CORRUGATED GALVANISED IRON SHEETS.

  +-----------+----------------+--------------+-------------+
  | Thickness |                |   Weight     |             |
  | B.W.G.    | Size of Sheets | Per Square   | Square Foot |
  |           |                |    Foot.     |  per Ton.   |
  +-----------+----------------+--------------+-------------+
  |           |     Feet.      |  lb.   oz.   |             |
  |   16      | 6 × 2 to 8 × 3 |   2    1     |      800    |
  | 17 × 18   | 6 × 2 ”  8 × 3 |   2    4     |     1050    |
  | 19 × 20   | 6 × 2 ”  8 × 3 |   1   12     |     1300    |
  | 21 × 22   | 6 × 2 ”  7 × 2½|   1    7     |     1600    |
  | 23 × 24   | 6 × 2 ”  7 × 2½|   1    3     |     1900    |
  | 25 × 26   | 6 × 2 ”  7 × 2½|   1    0     |     2250    |
  +-----------+----------------+--------------+-------------+


    THICKNESS AND WEIGHT OF GALVANISED SHEET IRON.

Size of sheet, 2 feet in width by from 6 to 9 feet in length.

  +------------+--------------+-------------+---------------+
  |    Wire    |    Weight    |      Wire   |      Weight   |
  |  Gauge.    |  Per Square  |      Gauge. |    Per Square |
  |            |      Foot.   |             |       Foot.   |
  +------------+--------------+-------------+---------------+
  |     No.    |       Oz.    |        No.  |       Oz.     |
  |      30    |       10     |        22   |       21      |
  |      29    |       11     |        21   |       24      |
  |      28    |       12     |        20   |       28      |
  |      27    |       14     |        19   |       33      |
  |      26    |       15     |        18   |       37      |
  |      25    |       16     |        17   |       43      |
  |      24    |       17     |        16   |       48      |
  |      23    |       19     |        14   |       60      |
  +------------+--------------+-------------+---------------+


    QUALITIES OF DIFFERENT ROPES EXPRESSED RELATIVELY.

  +--------------+----------+-------------+--------+-------------+
  |              | Strength.| Rigidity.   | Weight |             |
  |              |          |             |  Dry.  | Stretching. |
  +--------------+----------+-------------+--------+-------------+
  | Italian Hemp |   --     |     1       |   1    | }           |
  | Baltic    ”  | 0·7  ·9  | 0·8 to 0·9  |   1    | }1/7 to 1/12|
  | Manilla   ”  | 0·9 to 1 |    0·75     |   0·88 | }           |
  | Flax         |   0·9    |    low      |  --    |     1/75    |
  | Iron Wire    |    3     |    high     |   4    |      --     |
  | Steel        |    6     |    high     |   4    |      --     |
  +--------------+----------+-------------+--------+-------------+

Steel wire rope stretches about 1/360, 1/250, and 1/100, of 1/4, 1/3,
and 1/2 the breaking weight.


    THE ATMOSPHERE.

The composition of the atmosphere is by volume, oxygen 20·8, nitrogen
79·2; by weight, oxygen 23, nitrogen 77. There are also minute
quantities of carbon dioxide, aqueous vapour, and ammonia.

The barometer falls about ½” for each 500’ increase of altitude the mean
temperature being 50° Fahr.


    WEIGHT OR PRESSURE.

   = 14·706 lbs. per square inch.
   = 29·92 inches of mercury.
   = 33·7 feet of water.


    SQUARES, CUBES, SQUARE ROOTS, AND CUBE ROOTS.

  +---------+--------+-----------+-------------+---------+
  |         |        |           |    Square   |  Cube   |
  |   No.   | Square |   Cube    |     Root    |  Root   |
  |         |        |           |       √     |    ∛    |
  +---------+--------+-----------+-------------+---------+
  |   1     |      1 |         1 |       1·0   |   1·0   |
  |   2     |      4 |         8 |       1·414 |  1·259  |
  |   3     |      9 |        27 |       1·732 |  1·442  |
  |   4     |     16 |        64 |       2·0   |  1·587  |
  |   5     |     25 |       125 |       2·236 |  1·709  |
  |   6     |     36 |       216 |       2·449 |  1·817  |
  |   7     |     49 |       343 |       2·645 |  1·912  |
  |   8     |     64 |       512 |       2·828 |  2·0    |
  |   9     |     81 |       729 |       3·0   |  2·080  |
  |  10     |    100 |      1000 |       3·162 |  2·154  |
  |  11     |    121 |      1331 |       3·316 |  2·223  |
  |  12     |    144 |      1728 |       3·464 |  2·289  |
  |  13     |    169 |      2197 |       3·60  |  2·35   |
  |  14     |    196 |      2744 |       3·74  |  2·41   |
  |  15     |    225 |      3375 |       3·87  |  2·46   |
  |  16     |    256 |      4096 |       4·0   |  2·51   |
  |  17     |    289 |      4913 |       4·12  |  2·58   |
  |  18     |    324 |      5832 |       4·24  |  2·62   |
  |  19     |    361 |      6859 |       4·35  |  2·66   |
  |  20     |    400 |      8000 |       4·47  |  2·71   |
  |  25     |    625 |     15625 |       5·0   |  2·92   |
  |  30     |    900 |     27000 |       5·47  |  3·10   |
  |  35     |   1225 |     42875 |       5·91  |  3·27   |
  |  40     |   1600 |     64000 |       6·32  |  3·41   |
  |  45     |   2025 |     91125 |       6·70  |  3·55   |
  |  50     |   2500 |    125000 |       7·07  |  3·68   |
  |  55     |   3025 |    166375 |       7·41  |  3·80   |
  |  60     |   3600 |    216000 |       7·24  |  3·91   |
  |  65     |   4225 |    274625 |       8·06  |  4·02   |
  |  70     |   4900 |    343000 |       8·36  |  4·12   |
  |  75     |   5625 |    421875 |       8·66  |  4·41   |
  |  80     |   6400 |    512000 |       8·94  |  4·30   |
  |  85     |   7225 |    614125 |       9·21  |  4·39   |
  |  90     |   8100 |    729000 |       9·48  |  4·48   |
  |  95     |   9025 |    857375 |       9·74  |  4·56   |
  | 100     |  10000 |   1000000 |      10·00  |  4·64   |
  | 110     |  12100 |   1331000 |      10·48  |  4·79   |
  | 120     |  14400 |   1728000 |      10·95  |  4·93   |
  | 130     |  16900 |   2197000 |      11·40  |  5·06   |
  | 140     |  19600 |   2744000 |      11·83  |  5·19   |
  | 150     |  22500 |   3375000 |      12·24  |  5·31   |
  | 160     |  25600 |   4096000 |      12·64  |  5·42   |
  | 170     |  28900 |   4913000 |      13·03  |  5·53   |
  | 180     |  32400 |   5832000 |      13·41  |  5·64   |
  | 190     |  36100 |   6859000 |      13·78  |  5·74   |
  | 200     |  40000 |   8000000 |      14·14  |  5·84   |
  | 210     |  44100 |   9261000 |      14·49  |  5·94   |
  | 220     |  48400 |  10648000 |      14·83  |  6·03   |
  | 230     |  52900 |  12167000 |      15·16  |  6·12   |
  | 240     |  57600 |  13824000 |      15·49  |  6·21   |
  | 250     |  62500 |  15625000 |      15·81  |  6·29   |
  | 260     |  67600 |  17576000 |      16·12  |  6·38   |
  | 270     |  72900 |  19683000 |      16·43  |  6·46   |
  | 280     |  78400 |  21952000 |      16·73  |  6·54   |
  | 290     |  84100 |  24389000 |      17·02  |  6·61   |
  | 300     |  90000 |  27000000 |      17·32  |  6·69   |
  | 310     |  96100 |  29791000 |      17·60  |  6·76   |
  | 320     | 102400 |  32768000 |      17·88  |  6·83   |
  | 330     | 108900 |  35937000 |      18·16  |  6·91   |
  | 340     | 115600 |  39304000 |      18·43  |  6·97   |
  | 350     | 122500 |  42875000 |      18·17  |  7·04   |
  | 360     | 129600 |  46656000 |      18·97  |  7·11   |
  | 370     | 136900 |  50653000 |      19·23  |  7·17   |
  | 380     | 144400 |  54872000 |      19·49  |  7·24   |
  | 390     | 152100 |  59319000 |      19·74  |  7·30   |
  | 400     | 160000 |  64000000 |      20·00  |  7·36   |
  | 410     | 168100 |  68921000 |      20·24  |  7·42   |
  | 420     | 176400 |  74088000 |      20·49  |  7·48   |
  | 430     | 184900 |  79507000 |      20·73  |  7·54   |
  | 440     | 193600 |  85184000 |      20·97  |  7·60   |
  | 450     | 202500 |  91125000 |      21·21  |  7·66   |
  | 460     | 211600 |  97336000 |      21·44  |  7·71   |
  | 470     | 220900 | 103823000 |      21·67  |  7·77   |
  | 480     | 230400 | 110592000 |      21·90  |  7·82   |
  | 490     | 240100 | 117649000 |      22·13  |  7·88   |
  | 500     | 250000 | 125000000 |      22·36  |  7·93   |
  | 510     | 260100 | 132651000 |      22·58  |  7·98   |
  | 520     | 270400 | 140608000 |      22·80  |  8·04   |
  | 530     | 280900 | 148877000 |      23·02  |  8·09   |
  | 540     | 291600 | 157464000 |      23·23  |  8·14   |
  | 550     | 302500 | 166375000 |      23·45  |  8·19   |
  | 560     | 313600 | 175616000 |      23·66  |  8·24   |
  | 570     | 324900 | 185193000 |      23·87  |  8·29   |
  | 580     | 336400 | 195192000 |      24·08  |  8·33   |
  | 590     | 348100 | 205379000 |      24·29  |  8·38   |
  | 600     | 360000 | 216000000 |      24·49  |  8·43   |
  | 610     | 372100 | 226981000 |      24·69  |  8·48   |
  | 620     | 384400 | 238328000 |      24·90  |  8·52   |
  +---------+--------+-----------+-------------+---------+


    TABLE TO CALCULATE WAGES AND OTHER PAYMENTS.

  +----------+-------------------+------------------+--------------+
  |    Year. |     Per Month.    |     Per Week.    |    Per Day.  |
  +----------+-------------------+------------------+--------------+
  |    £     |      £   s.   d.  |     £   s.   d.  |   s.   d.    |
  |    1     |      0   1    8   |     0   0    4½  |   0    0¾    |
  |    2     |      0   3    4   |     0   0    9¼  |   0    1¼    |
  |    3     |      0   5    0   |     0   1    1¾  |   0    2     |
  |    4     |      0   6    8   |     0   1    6½  |   0    2¾    |
  |    5     |      0   8    4   |     0   1   11   |   0    3¼    |
  |    6     |      0  10    0   |     0   2    1¾  |   0    4     |
  |    7     |      0  11    8   |     0   2    8¼  |   0    4½    |
  |    8     |      0  13    4   |     0   3    1   |   0    5¼    |
  |    9     |      0  15    0   |     0   3    5½  |   0    6     |
  |   10     |      0  16    8   |     0   3   10¼  |   0    6½    |
  |   11     |      0  18    4   |     0   4    3¾  |   0    7¼    |
  |   12     |      1   0    0   |     0   4    7½  |   0    8     |
  |   13     |      1   1    8   |     0   5    0   |   0    8½    |
  |   14     |      1   3    4   |     0   5    4½  |   0    9¼    |
  |   15     |      1   5    0   |     0   5    9¼  |   0    9¾    |
  |   16     |      1   6    8   |     0   6    1¾  |   0   10½    |
  |   17     |      1   8    4   |     0   6    6½  |   0   11¼    |
  |   18     |      1  10    0   |     0   6   11   |   0   11¾    |
  |   19     |      1  11    8   |     0   7    3½  |   1    0½    |
  |   20     |      1  13    4   |     0   7    8¼  |   1    1¼    |
  |   30     |      2  10    0   |     0  11    6½  |   1    7¾    |
  |   40     |      3   6    8   |     0  15    4½  |   2    2¼    |
  |   50     |      4   3    4   |     0  19    2¾  |   2    9     |
  |   60     |      5   0    0   |     1   3    1   |   3    3½    |
  |   70     |      5  16    8   |     1   6   11   |   3   10     |
  |   80     |      6  13    4   |     1  10    9¼  |   4    4½    |
  |   90     |      7  10    0   |     1  14    7½  |   4   11½    |
  |  100     |      8   6    8   |     1  18    5½  |   5    5¾    |
  +----------+-------------------+------------------+--------------+

If the Wages be Guineas instead of Pounds, for each Guinea add 1_d._ to
each month, or 1/4_d._ to each week.


    HANDY UNIVERSAL INTEREST TABLE.

    (By Alfred Fryer.)

Showing the Interest, to the 100th part of a farthing, on any Sum from
£1 to £1,000,000, for any number of days, at any rate per cent.

  +----------+---------+-----+------+-----+--------+
  |          |    £    |  s. |  d.  |  f. | 100ths |
  +----------+---------+-----+------+-----+--------+
  |        1 |       0 |   0 |   1  |   2 |      3 |
  |        2 |       0 |   0 |   1  |   1 |     26 |
  |        3 |       0 |   0 |   1  |   3 |     89 |
  |        4 |       0 |   0 |   2  |   2 |     52 |
  |        5 |       0 |   0 |   3  |   1 |     15 |
  |        6 |       0 |   0 |   3  |   3 |     78 |
  |        7 |       0 |   0 |   4  |   2 |     41 |
  |        8 |       0 |   0 |   5  |   1 |      4 |
  |        9 |       0 |   0 |   5  |   3 |     67 |
  |       10 |       0 |   0 |   6  |   2 |     30 |
  |       20 |       0 |   1 |   1  |   0 |     60 |
  |       30 |       0 |   1 |   7  |   2 |     90 |
  |       40 |       0 |   2 |   2  |   1 |     21 |
  |       50 |       0 |   2 |   8  |   3 |     51 |
  |       60 |       0 |   3 |   3  |   1 |     81 |
  |       70 |       0 |   3 |  10  |   0 |     11 |
  |       80 |       0 |   4 |   4  |   2 |     41 |
  |       90 |       0 |   4 |   11 |   0 |     71 |
  |      100 |       0 |   5 |   5  |   3 |      1 |
  |      200 |       0 |  10 |  11  |   2 |      3 |
  |      300 |       0 |  16 |   5  |   1 |      4 |
  |      400 |       1 |   1 |  11  |   0 |      5 |
  |      500 |       1 |   7 |   4  |   3 |      7 |
  |      600 |       1 |  12 |  10  |   2 |      8 |
  |      700 |       1 |  18 |   4  |   1 |     10 |
  |      800 |       2 |   3 |  10  |   0 |     11 |
  |      900 |       2 |   9 |   3  |   3 |     12 |
  |    1,000 |       2 |  14 |   9  |   2 |     14 |
  |    2,000 |       5 |   9 |   7  |   0 |     27 |
  |    3,000 |       8 |   4 |   4  |   2 |     41 |
  |    4,000 |      10 |  19 |   2  |   0 |     55 |
  |    5,000 |      13 |  13 |  11  |   2 |     68 |
  |    6,000 |      16 |   8 |   9  |   0 |     82 |
  |    7,000 |      19 |   3 |   6  |   2 |     96 |
  |    8,000 |      21 |  18 |   4  |   1 |     10 |
  |    9,000 |      24 |  13 |   1  |   3 |     23 |
  |   10,000 |      27 |   7 |  11  |   1 |     37 |
  |   20,000 |      54 |  15 |  10  |   2 |     74 |
  |   30,000 |      82 |   3 |  10  |   0 |     11 |
  |   40,000 |     109 |  11 |   9  |   1 |     48 |
  |   50,000 |     136 |  19 |   8  |   2 |     85 |
  |   60,000 |     164 |   7 |   8  |   0 |     22 |
  |   70,000 |     191 |  15 |   7  |   1 |     59 |
  |   80,000 |     219 |   3 |   6  |   0 |     96 |
  |   90,000 |     246 |  11 |   6  |   0 |     32 |
  |  100,000 |     273 |  19 |   5  |   1 |     70 |
  |  200,000 |     547 |  18 |  10  |   3 |     40 |
  |  300,000 |     821 |  18 |   4  |   1 |      9 |
  |  400,000 |    1095 |  17 |   9  |   2 |     79 |
  |  500,000 |    1369 |  17 |   3  |   0 |     49 |
  |  600,000 |     643 |  16 |   8  |   2 |     19 |
  |  700,000 |     917 |  16 |   1  |   3 |     89 |
  |  800,000 |    2191 |  15 |   7  |   1 |     59 |
  |  900,000 |    2465 |  15 |   0  |   3 |     29 |
  |1,000,000 |    2739 |  14 |   6  |   0 |     99 |
  +----------+---------+-----+------+-----+--------+


  THE RULE.--Multiply the number of £ upon which the interest is to be
  calculated by the number of days, and then multiply this product by the
  rate of interest, strike out the last two figures to the right hand, and
  find from the table the interest on the remaining figures.

  _Example._--What is the interest of £271 for 90 days at 7 per cent. per
  ann.?

  Multiply            £271
        by              90 number of days
                     ------
  then multiply      24390
        by               7 rate of interest
                     ------
                     170730
  strike out last 2 figures,
  viz.: 30, and in the table    £ |   s. |  d. | f. | 100ths. |
  against 1000 you find         2 |  14  |  9  |  2 |   14    |
     ”     700    ”             1 |  18  |  4  |  1 |   10    |
     ”       7    ”             0 |   0  |  4  |  2 |   41    |
                                -------------------------------
                                4 |  13  |  6  |  1 |   65    |

If the product of the number of £ on which the interest be calculated
× number of days × rate of interest is, after elision of the last two
figures, a multiple of a million, multiply the figures in table against
1,000,000 by the number of that multiple.




    AUSTRALIAN MINING REGULATIONS.


     NEW SOUTH WALES.

By the Mining Act of 1874, the Governor was empowered to proclaim Crown
lands to be gold-fields, and to grant “miners’ rights” at a fee of
10_s._, between January and June exclusive, of each year, and 5_s._
after that date in each year, subject to certain regulations to be from
to time to time prescribed. All miners’ rights terminate with the last
day of the year, and without a miner’s right no person is allowed to
mine for gold, under a penalty not exceeding £10. Business licences may
also be granted enabling persons to occupy Crown lands within
gold-fields for business purposes, on payment of a fee of £1 for a year,
and 10_s._ for six months. Leases of auriferous lands may be obtained in
accordance with the regulations for the time being, the rent to be fixed
by the Governor in Council (£1 per acre for one to twenty-five acres
alluvial and quartz reef). Special leases may be granted up to 100
acres. By the regulations issued on March 31, 1882, it is enacted that
any parcel of new or unworked land, taken possession of with a view of
obtaining a lease, shall be efficiently and continuously worked from the
date of possession by not less than two men to four acres or less, and
an additional man to every other two acres, under pain of forfeiture of
the title to the land. The holder of a miner’s right may apply for
authority to search for gold, and the holder of a mineral licence may
apply for authority to search for minerals on land aforesaid.

At the expiration of two months the Warden may grant an authority to
search on such land, and the holder may, within the period named in the
authority, remove from any vein or lode outcropping at the surface 28
lb. weight, but must not break the ground.

Application to lease may be made and lodged with the Warden of the
district, or nearest Warden’s Clerk, within one month from date of
authority to search:

1. By the holder of an authority to search, the area not to exceed 20
acres for gold-mining, or 80 acres for other minerals.

2. By the holder of a miner’s right, the area not to exceed 20 acres of
ordinary auriferous land, or 40 acres of alluvial auriferous land, where
the mining operations will be conducted through basaltic rock formation,
or where steam machinery is necessary to contend against water, or where
a large outlay of money is necessary.

3. By the holder of a mineral licence to mine for silver, lead, tin,
antimony, the area not to exceed 80 acres.

4. By the holder of a prospecting licence, within 30 days after
discovery of an auriferous quartz vein in a prospecting area, area not
to exceed 20 acres.

5. By the holder of a miner’s right or mineral licence, for the purpose
of cutting races, conveying water or detritus to any mine, tramway,
machine site, smelting works, water conservation, or other purpose
connected with mining.

With every application to lease, the applicant, not being the owner
of the land, shall deposit for rent for first half year, 10_s._ for
every acre or part of an acre. Fees are required for the survey of the
leasehold and road thereto, and also for appraising damage.

The owner may agree with the applicant to lease upon the amount of
compensation and the mode of payment of same, otherwise an appraiser
appointed by the Government may assess the amount of compensation to be
paid by the applicant to the owner. If the applicant fail to pay the
compensation awarded within the time specified, the application shall
become void, and all moneys deposited shall become forfeited.


    VICTORIA.

Miners’ rights are issued at the rate of 5_s._ per annum, and
consolidated miners’ rights may be issued on the application of the
manager or trustees of any company agreeing to work in partnership any
claims registered under the Act, on payment of a sum at the prescribed
rate multiplied by the number of miners’ rights so consolidated. Miners’
rights entitle the holders to take possession of, and reside on and
mine, so much of the Crown lands as may be prescribed by the bylaws of
the Local Mining Board. Business licences enable the holders to occupy
and carry on business on the gold-fields, on lands not exceeding one
acre in extent, and are issued at £2 10_s._ for six months, and £5 for
twelve months. A lease may be granted of not more than 100 acres in one
lot for such term as the Governor may determine and at a nominal rent,
to any holder of a miners’ right who may be desirous to prospect for
gold in any place where sinking through basalt will be necessary, and to
which no part of any gold workings shall be nearer than five miles, one
mile being allowed to be marked off for the prospecting, and the lease
of 100 acres to be granted only in case of remunerative gold being
found.

Gold-mining leases may be granted under Part I. of the “Mines Act 1890,”
of Crown lands, pastoral areas, also lands alienated in fee since
December 29, 1884, lands licensed or leased (with right of purchase)
since December 29, 1884.

Leases to mine for gold and silver may be granted under Part II. of the
“Mines Act 1890,” of lands alienated in fee prior to December 29, 1884.

The rent on gold-mining leases of any lands--except lands alienated in
fee prior to December 29, 1884--is at the rate of 5_s._ per acre per
annum, payable half-yearly in advance; and for lands alienated in fee
prior to December 29, 1884, the rent is, for any area up to 40 acres, £1
per annum, payable quarterly in advance in each case. On mineral leases
the rent is not less than 3_d._ or more than £5 per acre per annum,
payable half-yearly, in advance.

The amount to be lodged with an application for mining lease is £5, and
such further sum as may be required to cover cost of survey.

Licences to cut, construct, and use races, drains, dams, and reservoirs
for mining purposes, may be granted for a term not to exceed fifteen
years, at a minimum rent of £2 per annum in advance.


    SOUTH AUSTRALIA.

A miner’s right authorises the holder to prospect for any metal,
mineral, coal, or oil, the property of the Crown; under a gold claim of
20 acres, a mineral claim not exceeding 40 acres, and a coal or oil
claim, 640 acres. Ownership of claim confers the right to reside
thereon, and preferential right to a lease.

The dimensions of a gold claim are for an ordinary reef claim, 100 by
600 feet, and an ordinary alluvial claim 30 by 30 feet, with a labour
condition requiring one man to be kept employed. A mineral claim of 40
acres requires two men; coal and oil claims (640 acres) require eight
men. A business licence (quarter acre in township, and one acre on other
land) costs 10_s._ for six months and £1 for one year. Occupation
licence (half acre), 2_s._ per annum, term fourteen years. A person may
hold any number of claims (except alluvial claims, of which only one can
be held at one time), but for each claim must hold a miner’s right.

Gold leases not exceeding 20 acres, term forty-two years, rent 1_s._ per
acre and 6_d._ in the pound on net profits; labour, one man to every 5
acres. Mineral leases not exceeding 40 acres, term forty-two years, rent
1_s._ per acre, and 6_d._ in the pound on net profits; labour, one man
to every 10 acres. Coal and oil leases (640 acres), term forty-two
years, rent 6_d._ per acre until coal or oil is found in payable
quantities, then 1_s._ per acre; labour, one man for every 40 acres.
Miscellaneous lease for salt and gypsum, 40 acres; mineral springs, 20
acres, and smelting works’ site, 5 acres, term forty-two years; labour
for salt and gypsum and mineral springs, two men for each 40 acres.

Any number of leases may be held, but a miner’s right for each is
required. All claims must be constantly worked, and must be registered
within thirty days after being pegged out.


    WESTERN AUSTRALIA.

On April 17, 1884, amended Mining Regulations were issued, empowering
the Governor to proclaim any portion of Crown land to be a gold-field,
and to appoint Wardens, who could grant miner’s rights to any person
upon payment of £1 per year, authorising the holder to search and mine
for gold on any waste land upon registering the occupation of the claim
with the Warden or other duly appointed officer.

Alluvial ordinary claims to comprise an area of 16 by 16 yards for one
person, ordinary river and steam claims to have a frontage of 20 yards
on the course of the river or stream, and a depth of 50 yards on both
banks; ordinary quartz claims not to exceed 50 feet in length on the
supposed course of the reef by a width not exceeding 400 feet. Any
ground taken up for mining and unoccupied and unworked for ten days to
be considered as abandoned.

On October 1, 1886, “Regulations for the Management of Gold-fields” came
into operation, dealing with the conditions under which a miner desirous
of prospecting may mark off and hold a protection area; also as regards
alluvial claims, and the rewards to be had for discoveries of new
gold-fields.

By an additional amended regulation, granted under regulations of
February 2, 1888, any protection area which after the date of the
grant thereof comes within the limits of a proclaimed gold-field,
may, notwithstanding such proclamation, continue to be held until the
expiration of twelve months from the date of such grant, or until
payable gold on such area is discovered, which ever shall first happen.
The labour conditions must however be fully complied with, or the
extension of time will cease, and the protection area will be forfeited.

Gold-mining leases are granted for areas not exceeding 25 acres, at an
annual rent, payable in advance, of 20_s._ per acre. The term may not
exceed twenty-one years. The leases are liable to cancellation unless
worked by the proper number of men, or machinery power equal to the men.
The leases can be determined by giving three months’ notice, and the
lessees have power to remove all machinery used on the land.


    QUEENSLAND.

On payment of 10_s._ the Governor may cause to be issued to any person
(not being an Asiatic or African alien), a mining licence for one year,
and on payment of the sum of £4 a business licence. All applications
for mineral leases to be made on the prescribed form, and to be
accompanied by the proper survey fee and the first year’s rent. The
yearly rental of every lease to be at the rate of 10_s._ per acre,
payable in advance, the term not to exceed twenty-one years, but a
further lease of twenty-one years may be granted on such terms as the
Minister deems equitable. Area not to exceed 100 acres.

Mining without a right is punishable by removal of the offender from the
field, and the infliction of a fine of £10, or one month’s imprisonment.

Miners desirous of prospecting for gold may mark off and hold protection
areas, ranging according to the distance from a proclaimed gold-field of
150 to 400 yards square. Such areas have to be pegged, registered, and
continuously worked. On payable gold being found and reported to the
Warden, the prospectors are entitled to a reward claim which varies from
two to twenty claims of the ordinary area. 50 feet frontage are allowed
to each miner on river and creek claims. On ordinary quartz claims, 50
feet along the line of reef, by a width of 400 feet, are allowed. The
extent of ground in any lode claim not to exceed 3 chains by 5 chains,
alluvial claim not to exceed 4 chains by 4 chains. This area may be
increased by the Warden when the ground is poor, or expensive machinery
has been erected. Europeans holding miners’ rights, which are granted
for ten years or less on payment of an annual rate of 10_s._, are
allowed to occupy and enclose, for the purpose of residence, an area of
land not exceeding a quarter of an acre, to be marked off in a
rectangular block, or as near thereto as possible, the frontage of which
to any road, creek, or water shall not exceed 72 feet, the boundaries to
be defined by corner pegs 3 inches in diameter and standing 18 inches
out of the ground, and can also occupy, under certain conditions,
market-garden areas not exceeding 5 acres. They are also entitled to
mine in Crown lands, to make dams, races, and tramways, to divert
waters, to put up and remove any building, and to use any timber,
gravel, or clay for their own building purposes. Upon erecting buildings
or making improvements on a business or residence area, to the value of
£5, the holder can have such area registered as exempt from the
condition of residence for a period not exceeding one year.

Leases of land not exceeding 25 acres for any term not exceeding 21
years are also granted for mining purposes at a yearly rental of £1 per
acre. These leases, however, are not granted on new gold-fields until
two years after proclamation.

The Mineral Lands Act of 1892, applies to lands on gold-fields and gives
the power to the holders of miner’s rights and licences to mine on land
sold, subject to reservation of gold and silver, on obtaining the
written sanction of the Warden or commissioner.


    TASMANIA.

A miner’s right, or prospector’s protection order, issued under the
Gold-fields Act (the fee for a miner’s right being 5_s._, and a
prospector’s licence 10_s._ per annum), authorises the holder to reside
upon a gold-field, and to occupy a quarter of an acre for residence, and
entitles him to a claim for mining purposes:--Alluvial, single claim, 35
yards by 35 yards; united claims, up to 10 men, 110 yards by 110 yards.
Creek claims; 35 yards by 35 yards along course of creek; united claims
not to exceed six men’s area. Extended alluvial claims; 70 yards by 70
yards, up to 170 yards by 170 yards for six men; also to take any
quantity of water and of timber required for mining purposes. Extended
alluvial claims of one acre for ground previously worked and abandoned
may be taken up. Prospecting claims, gold, not exceeding 10 acres. Fee
for registration, which is not compulsory, 2_s._ 6_d._; survey 25_s._
United claim of 10, fee 5_s._; survey, £2. Leases not to exceed 10
acres, except in special cases by permission of the Minister; term, ten
years; rent, £1 per acre. Leases may be amalgamated to the extent of 60
acres. Lessee has the right to renewal for ten years, rent not to exceed
£3 an acre. Fee for preparation of lease, £1; transfer, 10_s._ Survey
fee, 10 acres, £3 15_s._ ordinary land; £5 10_s._ heavy bush. On the
West Coast the survey fees are: 1 acre and under, £1 15_s._; 2 acres,
and under 5 acres, £3 15_s._; under 10 acres, £5 10_s._, up to a maximum
of £23 for not exceeding 320 acres.

Leases are liable to forfeiture by the Governor in Council if the rent
is not paid in advance, or the labour conditions are not complied with.

Licences to occupy land upon a gold-field, for the purpose of
cultivation, are issued under the Waste Lands Acts. Area, 5 acres or
under, rent £2.


    NEW ZEALAND.

The price of a “miner’s right” is 10_s._ per year, which authorises the
holder to mine on Crown lands throughout the colony outside of a native
district; and 20_s._, which authorises him to mine on native lands and
Crown lands, or such other sum as shall not be less than the sum which
the Governor may have agreed to pay to the owners of the land as
consideration for the right to mine thereon. Consolidated miners’ rights
are issued at the rate of a single miner’s right (10_s._), multiplied
by the number of miners’ rights which the consolidated right is to
represent. Business licences, to be in force for twelve or six months,
are issued on payment in advance of £3 for a yearly, and £1 10_s._ for
a half-yearly licence respectively. The holder of a miner’s right is
entitled to enter upon any Crown land for the purpose of prospecting
and searching for gold, and to take and maintain possession of a parcel
or parcels of land and work the same, subject to the regulations and
provisions of the Act; he is also authorised to cut timber for removal
or for the erection of a place of residence or of business, and with
the Warden’s consent, to make tramways or roads for mining purposes.
Claims are of four kinds--alluvial deposits and river or creek beds;
quartz lodes, reefs, and leaders; sea-beach claims; prospecting claims
and areas. Claims may be marked out by any person desiring the exclusive
occupation of the land, but they must be continuously worked, or they
are liable to forfeiture.

The holder of a miner’s right can obtain a licence for the occupation of
land as a licensed holding by paying the necessary expenses for
surveying, &c., together with a deposit of £5 in respect of such
application.




    INDEX


  A

  Adobie hut, 127, 128

  Aërial tramways, 112

  Amalgam, Retort for small quantities of, 142;
    squeezing, 155

  Amalgamation of gold, 30

  Amalgamators, 91-93

  Aneroid barometer, Use of, for leveling, 160, 161

  Antifriction compound, 165

  Aqueous origin of ore deposits, 36-38

  Assay apparatus, Simple form of, 14, 15

  Assaying gold by amalgamation, 30

  Areas, To lay out, 174, 175

  Atherton, on native sulphide of gold, 45, 46

  Atmosphere, 190

  Atomic weights, 181, 182

  Australian mining regulations, 194, _et seq._;
    New South Wales, 194;
    Victoria, 195;
    S. Australia, 195;
    W. Australia, 195;
    Queensland, 198;
    Tasmania, 200


  B

  Battery, the best way to test value of lodes, 31

  Becker, on Comstock lode, 42, 43

  Belting, Data as to, 178, 180

  Bischof, experiment on formation of dendroidal gold, 39

  Black jack, 33

  Blanket tables, 79

  Boilers, How to clean, 164

  Boiling points, 184

  Boring, 172

  Bottom, Signs of, 20

  Braidwood nugget, 54

  Brass, How to clean, 165

  Brückner furnace, 105

  Bucket, Hide, 139

  Bulk of materials, 180

  Burra Burra Mine, 24

  Bush bed, 130

  Bynoe harbour, Tin at, 32


  C

  California pump, 171

  Challenger ore feeder, 74, 75

  Charcoal, To make, 141

  Chemical formulas, 182

  Chlorine as a lixiviator, 73-75

  Company formation, 113-126

  Comstock lode, 42, 43

  Copper mine at Burra Burra, 24

  Copper plates, Scaling, 144, 145;
    Silvering, 149;
    Dressing, 151

  Correspondence, How to make copies of, 137

  Cube roots, 191

  Cubes, 191

  Cyanide of potassium, Use of, in extracting gold, 95, 96


  D

  Daintree, on deposition of gold from chloride, 51

  Diamond drilling, 173

  Directors of companies, 114 _et seq._

  Dodge stone-breakers, 69, 70

  Dolly, 152

  Drift, Origin of gold in, 49

  Dry blowing, 18

  Dugout, 128

  Duncan pan, 91


  E

  Electricity as a motive power and transmitter, 111, 112

  Electrolytic process of extracting gold, 96-99

  Elements, Table of, 181, 182

  Eurieowie, Tin at, 32


  F

  Filter, 135, 136

  Fire, Mode of producing, 137

  Fire-lute, 166

  Flooded Stream, How to cross a, 138

  Flumes, 63

  Forge, Temporary, 140

  Freezing-points, 184

  Frue vanner, 89, 90

  Fuels, Heat values of, 184

  Furnaces used in calcining, 101 _et seq._

  Fusing points, 184


  G

  Gold, Value of, 1;
    Early notices of, 1, 2;
    Origin and sources of, 2-7;
    Modes of occurrence, 10, 11;
    Prospecting for, 13 _et seq._;
    Signs of, 26;
    Assaying, by amalgamation, 30;
    associated with tin ores, 32, 33;
    Relation of, to volcanic action, 36;
    its probable mode of occurrence in early geological times, 38, 39;
    Mode of deposition in quartz, 39, 55, 57;
    Formation of sulphides of, 39, 40;
    Precipitation of, in pyrites, 41, 42, 51-54;
    Solution of, by mine water, 42;
    Opinion as to growth of, in drift deposits 48;
    Daintree on its deposition from chloride, 51;
    Wilkinson on its precipitation on iron pyrites, 51, 52

  Gold (Alluvial) Origin of, 17, 49, 50, 51;
    Prospecting for, 17

  Gold extraction, 11, 12, 59 _et seq._;
    necessity of scientific procedure, 60;
    German organisation, 60;
    early methods, 61;
    modern methods, 61 _et seq._;
    hydraulicing, 62, 65;
    mills and crushers, 66-72;
    power and water for batteries, 73, 74;
    ore feeders, 74, 75;
    stamp mills, 76-78;
    screens, 78;
    blanket tables, 79;
    treatment of pyritous ores, 80;
    mode of saving the gold, 81;
    treatment of ferruginous ores, 82;
    cleaning and scaling plates, 83;
    retorting amalgam, 84-86;
    percussion tables, 88;
    Frue vanner, 89, 90;
    pan concentrators, 90;
    amalgamators, 91-93;
    lixiviation, 93 _et seq._;
    calcination, 100 _et seq._;
    how to avoid loss in cleaning up, 148

  Gold-field, Mount Brown 17, 18

  Griffin Mill, 67, 69

  Grusonwerk ball mill, 71

  Gutters, 20


  H

  Hammock, 130, 132

  Heated bearings, Cooling compound for, 163

  Heat values of fuels, 184

  Horse-power of engines, 144,
    amount required for pumping water, 172

  Horse-shoe furnace, 103

  Howell-White furnace, 104, 105

  Huntingdon mill, 69

  Hydraulicing, 62, 65

  Hydraulics, 171

  Hydro-thermal origin of early deposits, 37, 38


  I

  Interest Tables, 193

  Iron, prevention of rust on, 165

  Iron extractor, 148

  Iron sheets, size and weight of, 189

  Ironstone “blows” as indicators of lodes, 26


  J

  Johnson, experiments on deposition of gold, 55-57


  L

  Lamp, Slush, 139

  Leads, Course of, 19

  Le Conte, on ore deposits, 36, 37

  Lemichel syphon, 66, 67

  Lenticular lodes, 24, 25

  Levelling instruments, 160, 161

  Living places, 127-130

  Lobley, on gold, 36

  Lodes, nature of, 8-10;
    prospecting for, 22;
    grass as an indicator of, 22;
    not of igneous origin, 23;
    Quartz fragments as indicators of, 23;
    Usual trend of, in Australia, 23;
    Sinuous outcrops of, 25, 26;
    Determining the value of, 26, 28, 31;
    Underlie of, in Australia, 27;
    Explanation of shutes in, 43;
    why junctions of, are richest in metallic ores, 44;
    proofs of their being formed now, 44;
    Newbery, on gold in pyritous lodes, 47;
    Double faulting of, 72

  Lode tin, 32

  Long tom, 62

  Loss in blasting, How to prevent, 142


  M

  Machinery, Protection of, from rusting, 166

  Mear’s process, 94

  Measuring inaccessible distances, 157;
    the width of a river, 157, 158;
    height of a tree, 159, 160;
    height of objects, 161

  Medicine case, 136

  Mensuration, 175

  Mercury, Retort for small quantities of, 143;
    Mode of supplying, to mortar boxes, 145

  Mercury extractor, 155

  Metals, 33

  Mine managers, 115 _et seq._

  Mine surveying problems, 176

  Mining regulations, 194-201

  Misfires, How to deal with, 141

  Molesworth furnace, 106

  Monitor, 64

  Mount Bischoff tin mine, 24

  Mount Brown gold-field, 17, 18

  Mount Morgan gold mine, 23, 94, 95

  Mount Shoobridge, Tin at, 32


  N

  Names of common chemical substances, 183

  Newbery, Experiments by, on modern growth of lodes, 44, 45, 53;
    on gold in pyritous lodes, 47;
    experiments in depositing gold on sulphides, 52, 53

  Newbery and Vautin process, 94

  New machines and processes, Advice as to adoption of, 120-122

  New Zealand, Mining regulations of, 201

  Northern territory hammock, 130-132

  Nuggets, Position of, 17;
    Formation of, 17;
    Origin of, 50, 53-58


  O

  Ore Deposits, Le Conte’s conclusions as to, 36, 37

  Ore reserves, Calculation of, 168-170

  Ore values, Estimating, 170

  Organic matter as a precipitant of gold, 51, 52, 53

  Otto engines, 110, 111


  P

  Percussion tables, 88

  Pipes, How to clear, 164

  Plants as a source of water, 134, 135

  Plattner process, 94

  Plummer blocks, Cleaning greasy, 163

  Pollok process, 95

  Power for mills, 147

  Prospect, First, 29;
    Determining value of, 29, 30, 31

  Puddlers, 153-155

  Pump, 155, 171

  Purchase of mines, Advice as to, 123

  Pyrites as a precipitant of gold, 41, 42, 51-54;
    Modern deposition of, 45;
    Mode of occurrence of gold in, 46, 47

  Pyritous ore, Mode of treatment of, 80


  Q

  Quartz veins, Rosales’s igneous theory of, 34;
    objections thereto, 35, 36


  R

  Rainfall, 178

  Reef. See _Lodes_

  Retort for small quantities of amalgam, 142;
    and of mercury, 143

  Reverberatory furnaces, 101 _et seq._

  Right angle, 158

  Rivers, To measure width of, 157, 158

  Robbery in gold-mills, Mode of preventing, 124-126

  Ropes, Durability of, 173;
    Qualities of, 190

  Rope-splicing, 166

  Rosales on origin of quartz veins, 32-34

  Rotomahana district, White and Pink Terraces in, 36

  Rust, Solvent for, 165;
    Protecting iron and steel from, 165

  Rutile, 32, 33


  S

  School of Mines, S. Australian, 118

  Screens, 78, 79

  Shaft, Size of, 19, 27;
    Logging up, 27, 28;
    Depth of, 162;
    Connection of, with underground workings, 176;
    Data connected with, 177

  Sheet-iron, Thickness and weight of, 189, 190

  Shutes, Explanation of, 43

  Signs, 185

  Silica terraces in the Rotomahana district, 36

  Silver ores, 31, 32

  Silvering copper plates, 149

  Skey, experiments on formation of sulphides, 39, 40;
    and on their properties, 41

  Sluice plates, 156

  Smelting, Rough, 141

  Soap, Serviceable, 138

  Specific gravity, 181, 182

  Square roots, 191

  Squares, 191

  Stamp mills, 76, 78;
    Power for, 147

  Steel, How to prevent rust in, 165

  Stetefeldt shaft furnace, 106

  Stream tin, 32

  Sulphide of gold, Formation of, 39, 40, 45, 46

  Sulphides, Experiments on properties of, 41, 42, 53;
    calcination of, 100 _et seq._


  T

  Tank, to find contents of, 189

  Telegraphic code, 138

  Tent, 128-130

  Thames gold-field, Siliceous sinter in, 36

  Thermometer scales, Table of, 184

  Thwaite-Denny furnace, 105, 106

  Thwaite power gas system, 110

  Thwaites’ furnace, 102

  Timber, Data as to, 174

  Tin, Minerals mistaken for, 32;
    How to distinguish them from, 33

  Tin-mines at Mount Bischoff, 24

  Tin ores, 32

  Tree, To measure height of, 160

  Tulloch ore feeder, 74, 75


  V

  Vein, to find lost part of, 167

  Velocity of falling fluids, 188


  W

  Wages, Table for calculating, 192

  Washing table, 79

  Water, Purifying, 132, 133;
    Roots as a source of, 134, 135;
    Filtering of, 135;
    Mode of supplying, to stamper boxes, 146;
    Plan for raising, 163;
    Data regarding, 171;
    Fresh and Salt, compared, 188;
    Pressure of, 189

  Water bag, 136

  Waterless power, 109-112

  Watson & Denny pan, 90

  Weight of materials, 180

  Weights and measures, 186, 187

  Welcome nugget, 54, 55

  Welcome Stranger nugget, 54

  Wilkinson, on deposition of gold in iron pyrites, 51, 52

  Windlass, 153

  Wolfram, 32, 33

  Woodside nuggets, 57


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    what is known of the Fertilization of Flowers, is given.”--_Journal
    of Botany_.

                      *       *       *       *       *

                  POPULAR WORKS ON BOTANY BY MRS. HUGHES-GIBB.

                  With Illustrations. Crown 8vo. Cloth. 2s. 6d.

                           HOW PLANTS LIVE AND WORK:

    =A Simple Introduction to Real Life in the Plant-world, Based on
    Lessons Originally Given to Country Children.=

                             By ELEANOR HUGHES-GIBB.

     =⁂= The attention of all interested in the Scientific Training
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     “The child’s attention is first secured, and then, in
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     “In every way well calculated to make the study of Botany
     ATTRACTIVE to the young.”--_Scotsman_

                      *       *       *       *       *

                 With Illustrations. Crown 8vo. Gilt, 2s. 6d.

                           =THE MAKING OF A DAISY;=

                           =“WHEAT OUT OF LILIES;”=

                   =And Other Studies from the Plant World.=

                      =_A Popular Introduction to Botany._=

                              By ELEANOR HUGHES-GIBB,

                        Author of _How Plants Live and Work_.


    “A BRIGHT little introduction to the study of Flowers.”
    --_Journal of Botany_.

    “The book will afford real assistance to those who can derive
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    =LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.=

                      *       *       *       *       *

                    Griffin’s Standard Publications

                                                          PAGE
    APPLIED MECHANICS, RANKINE, BROWNE, JAMIESON,        35,46,34
    CIVIL ENGINEERING,                 PROF. RANKINE,          35
    DESIGN OF STRUCTURES,              S. ANGLIN,              26
    BRIDGE-CONSTRUCTION,               PROF. FIDLER,           26
    DESIGN OF BEAMS,                   W. H. ATHERTON,         27
    DOCK ENGINEERING,                  B. CUNNINGHAM,          27
    ENGINEERING DRAWING,               S. H. WELLS,            27
    CONSTRUCTIONAL STEELWORK,          A. W. FARNSWORTH,       26
    CENTRAL ELECTRICAL STATIONS,       C. H. WORDINGHAM,       48
    ELECTRICITY CONTROL,               L. ANDREWS,             48
         ”      METERS,                H. G. SOLOMON,          49
    LIGHT RAILWAYS,                    W. H. COLE,             30
    SEWAGE DISPOSAL WORKS,             SANTO CRIMP,            76
    SANITARY ENGINEERING,              F. WOOD,                78
    TRAVERSE TABLES,                   R. L. GURDEN,           33
    LOCOMOTIVE ENGINEERING,            W. F. PETTIGREW,        30
    LOCOMOTIVE COMPOUNDI               J. F. GAIRNS,           30
    VALVES AND VALVE-GEARING,          CHAS. HURST,            31
    HINTS ON DESIGN,                   CHAS. HURST,            31
    MARINE ENGINEERING,                A. E. SEATON,           44
    ENGINE-ROOM PRACTICE,              J. G. LIVERSIDGE,       29
    POCKET-BOOK,                       SEATON AND ROUNTHWAITE, 44
    PRESENT DAY SHIPBUILDING,          T. WALTON,              38
    DESIGN OF SHIPS,                   PROF. HARVARD BILES,    38
    STEEL VESSELS,                     T. WALTON,              38
    STABILITY OF SHIPS,                SIR E. J. REED,         38
    NAUTICAL SERIES,                   Ed. by CAPT. BLACKMORE, 39
    THE STEAM-ENGINE,                  RANKINE, JAMIESON,   35,34
    GAS, OIL, AND AIR-ENGINES,         BRYAN DONKIN,           28
    BOILERS: LAND AND MARINE,          T. W. TRAILL,           29
     ”   STEAM,                        R. D. MUNRO,            32
     ”   KITCHEN,                      R. D. MUNRO,            32
     ”   HEAT EFFICIENCY OF,           BRYAN DONKIN,           28
    OIL FUEL,                          SIDNEY H. NORTH,        29
    MACHINERY AND MILLWORK,            PROF. RANKINE,          35
    PUMPING MACHINERY,                 H. DAVEY,               37
    HYDRAULIC MACHINERY,               PROF. ROBINSON,         37
    GRINDING MACHINERY,                R. B. HODGSON,          33
    LUBRICATION AND LUBRICANTS,        ARCHBUTT & DEELEY,      32
    RULES AND TABLES,                  RANKINE AND JAMIESON,   36
    BONUS TABLES,                      H. A. GOLDING,          31
    ELECTRICAL POCKET-BOOK,            MUNRO AND JAMIESON,     48
    THE CALCULUS FOR ENGINEERS,        PROF. ROBT. H. SMITH,   45
    MEASUREMENT CONVERSIONS,           PROF. ROBT. H. SMITH,   45
    CHEMISTRY FOR ENGINEERS,           BLOUNT & BLOXAM,        46

                      *       *       *       *       *

    LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *
    Fourth Edition, _Revised, with Numerous Diagrams, Examples, and
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                          THE DESIGN OF STRUCTURES:

        =A Practical Treatise on the Building of Bridges, Roofs, &c.=

                             by S. ANGLIN, C. E.,

    Master of Engineering, Royal University of Ireland, late Whitworth
    Scholar, &c.

    “We can unhesitatingly recommend this work not only to the
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                      *       *       *       *       *

    Third Edition, _Thoroughly Revised. Royal 8vo. With numerous
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                           A PRACTICAL TREATISE ON
                             BRIDGE-CONSTRUCTION:

             =Being a Text-book on the Construction of Bridges in
                                Iron and Steel.=

              FOR THE USE OF STUDENTS, DRAUGHTSMEN, AND ENGINEERS.
                      BY T. CLAXTON FIDLER, M. INST. C. E.,
                Prof. of Engineering, University College, Dundee.

    “The new edition of Mr. Fidler’s work will again occupy the same
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                      *       *       *       *       *

    _In Medium 8vo. Handsome Cloth. Pp. i-xv + 248, with over 100
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                           CONSTRUCTIONAL STEELWORK:

    =Being Notes on the Practical Aspect and the Principles of Design,
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                              By A. W. FARNSWORTH,
          Associate Member of the Institute of Mechanical Engineers.

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                      *       *       *       *       *

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                      *       *       *       *       *

    In Large 8vo. Handsome Cloth, Gilt, Uniform with _Stability of
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                      The Principles and Practice of
                             DOCK ENGINEERING.
            By BRYSSON CUNNINGHAM, B. F., ASSOC. M. INST. C. E.,
       Of the Engineers’ Department, Mersey Docks and Harbour Board.

                             GENERAL CONTENTS.

    Historical and Discursive.--Dock Design.--Constructive
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                       *       *       *       *       *

            Fourth Edition. In Two Parts, Published Separately.

                             A TEXT-BOOK OF
                     Engineering Drawing and Design.

    VOL. I.--Practical Geometry, Plane and Solid. 4s. 6d.
    VOL.II.--Machine and Engine Drawing and Design. 4s. 6d.

                                   BY
          SIDNEY H. WELLS, WH. SC., A.M.I.C.E., A.M.I.MECH.E.,

          Principal of the Battersea Polytechnic Institute, &c.

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                      *       *       *       *       *

    In Large Crown 8vo. Handsome Cloth. With 201 Illustrations. 6s. net.

                              AN INTRODUCTION TO
                             =THE DESIGN OF BEAMS,=
                              GIRDERS, AND COLUMNS
                          _IN MACHINES AND STRUCTURES._

                        With Examples in Graphic Statics.

                    By WILLIAM H. ATHERTON, M.SC., M.I.MECH.E.

    “A very useful source of information.... A work which we commend
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                      *       *       *       *       *

        LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

           Nearly Ready. In Handsome Cloth. With 252 Illustrations.

                       THE THEORY OF THE STEAM TURBINE.

         A Treatise on the History, Development, and Principles of
                       Construction of the Steam Turbine.

                              By ALEXANDER JUDE.

    Contents.--The Theory of the Steam Turbine.--Historical Notes on
    Turbines.--The Velocity of Steam.--Types of Steam Turbines.--
    Practical Turbines.--The Efficiency of Large Turbines.--The
    Trajectory of the Steam.--Efficiency of Turbines.--Turbine Vanes.
    --Disc Friction in Turbines.--Specific Heat of Superheated Steam.--
    Governing Steam Turbines.--Steam Consumption of Turbines.--The
    Whirling of Shafts.--Bibliography.--INDEX.

                      *       *       *       *       *

          Works by BRYAN DONKIN, M.Inst.C.E., M.Inst.Mech.E., &c.

           NOW READY.  FOURTH EDITION, Revised and Enlarged. With
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                                A TREATISE ON
                          GAS, OIL, AND AIR ENGINES.

                  By BRYAN DONKIN, M.Inst.C.E., M.Inst.Mech.E.

    Contents.--Part I.--=Gas Engines:= General Description of Action and
    Parts.--Heat Cycles and Classification of Gas Engines.--History of
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    Engines.--German Gas Engines.--Gas Production for Motive Power.
    --Utilisation of Blast-furnace and Coke-oven Gases for Power.--The
    Theory of the Gas Engine.--Chemical Composition of Gas in an Engine
    Cylinder.--Utilisation of Heat in a Gas Engine.--Explosion and
    Combustion in a Gas Engine.--PART II.--=PETROLEUM ENGINES:= The
    Discovery, Utilisation, and Properties of Oil.--Method of Treating
    Oil.--Carburators.--Early Oil Engines.--Practical Application of Gas
    and Oil Engines.--PART III.--=AIR ENGINES.=--APPENDICES.--INDEX.

    “The best book now published on Gas, Oil, and Air Engines.”
    --_Engineer._

    “A thoroughly reliable and exhaustive treatise.”--_Engineering._

                      *       *       *       *       *

             In Quarto, Handsome Cloth. With Numerous Plates. 25s.

                     THE HEAT EFFICIENCY OF STEAM BOILERS
                         =(LAND, MARINE, AND LOCOMOTIVE).=

    With many Tests and Experiments on different Types of Boilers,
    as to the Heating Value of Fuels, &c., with Analyses of Gases and
    Amount of Evaporation, and Suggestions for the Testing of Boilers.

                         By BRYAN DONKIN, M.Inst.C.E.

    General Contents.--Classification of Different Types of Boilers.
    --425 Experiments on English and Foreign Boilers with their Heat
    Efficiencies shown in Fifty Tables.--Fire Grates of Various Types.
    --Mechanical Stokers.--Combustion of Fuel in Boilers.--Transmission
    of Heat through Boiler Plates, and their Temperature.--Feed Water
    Heaters, Superheaters, Feed Pumps, &c.--Smoke and its Prevention.
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    _With Plates illustrating Progress made during recent years, and the
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    “Probably the MOST EXHAUSTIVE _resumé_ that has ever been collected.
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                      *       *       *       *       *

         LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

            Fourth Edition, Revised. Pocket-Size, Leather, 12s. 6d.

                          BOILERS, MARINE AND LAND:
                       THEIR CONSTRUCTION AND STRENGTH.

       A Handbook of Rules, Formulæ, Tables, &C, Relative to Material,
             Scantlings, and Pressures, Safety Valves, Springs,
                         Fittings and Mountings, &c.

            FOR THE USE OF ENGINEERS, SURVEYORS, BOILER-MAKERS,
                               AND STEAM USERS.

                    By T. W. TRAILL, M.INST.C.E., F.E.R.N.,
           Late Engineer Surveyor-in-Chief to the Board of Trade.

           =⁂= TO THE SECOND AND THIRD EDITIONS MANY NEW TABLES for
           Pressure, up to 200 LBS. per SQUARE INCH have been added.

    “THE MOST VALUABLE WORK on Boilers published in England.”
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    “Contains an Enormous Quantity of Information Arranged in a Very
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                      *       *       *       *       *

                FIFTH EDITION. Large Crown 8vo. With numerous
                            Illustrations. 6s. net.

                             ENGINE-ROOM PRACTICE:

    A Handbook for Engineers and Officers in the Royal Navy and
    Mercantile Marine, Including the Management of the Main and
    Auxiliary Engines on Board Ship.

                  By JOHN G. LIVERSIDGE, A.M.I.C.E.,
                      Commander Engineer, Malta.

    _Contents._--General Description of Marine Machinery.--The
    Conditions of Service and Duties of Engineers of the Royal Navy.
    --Entry and Conditions of Service of Engineers of the Leading
    S.S. Companies.--Raising Steam.--Duties of a Steaming Watch
    on Engines and Boilers.--Shutting off Steam.--Harbour Duties
    and Watches.--Adjustments and Repairs of Engineslic Machinery.
    --Air-Compressing Pumps.--Refrigerating Machines.--Machinery of
    Destroyers.--Th.--Preservation and Repairs of “Tank” Boilers.--The
    Hull and its Fittings.--Cleaning and Painting Machinery.--
    Reciprocating Pumps, Feed Heaters, and Automation Feed-Water
    Regulators.--Evaporators.--Steam Boats.--Electric Light Machinery.
    --Hydraulic Machinery.--Air Compressing Pumps.--Refrigerating
    Machines.--The Machinery of Destroyers--The Management of Water-Tubs
    Boilers.--Regulations for Entry of Assistant Engineers, R.N.--
    Questions given in Examinations for Promotion of Engineers, R.N.--
    Regulations respecting Board of Trade Examinations for Engineers, &c

    “The contents CANNOT FAIL TO BE APPRECIATED.”--_The Steamship._

    “This VERY USEFUL BOOK.... Illustrations are of GREAT IMPORTANCE
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                      *       *       *       *       *

            In Large Crown 8vo, Cloth. Fully Illustrated. 5s. net.

                                  OIL FUEL:
                 ITS SUPPLY, COMPOSITION, AND APPLICATION.

                              BY SIDNEY H. NORTH,
                    LATE EDITOR OF THE “PETROLEUM REVIEW.”

    Contents.--The Sources of Supply.--Economic Aspect of Liquid Fuel.--
    Chemical Composition of Fuel Oils.--Conditions of Combustion in Oil
    Fuel Furnaces.--Early Methods and Experiments.--Modern Burners and
    Methods.--Oil Fuel for Marine Purposes.--For Naval Purposes.--On
    Locomotives.--For Metallurgical and other Purposes.--Appendices.
    --Index.


    “Everyone interested in this important question will welcome Mr.
    North’s excellent text-book.”--_Nature._

                      *       *       *       *       *

       LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

         Second Edition, Revised. With numerous Plates reduced from
           Working Drawings and 280 Illustrations in the Text. 21s.

                                  A MANUAL OF
                            LOCOMOTIVE ENGINEERING:

            A Practical Text-Book for the Use of Engine Builders,
                       Designers and Draughtsmen, Railway
                             Engineers, and Students.

                      By WILLIAM FRANK PETTIGREW, M.Inst.C.E.

                With a Section on American and Continental Engines.

                           By ALBERT F. RAVENSHEAR, B.Sc.,
                           Of His Majesty’s Patent Office.

    _Contents._--Historical Introduction, 1763-1863.--Modern
    Locomotives: Simple.--Modern Locomotives: Compound.--Primary
    Consideration in Locomotive Design.--Cylinders, Steam Chests, and
    Stuffing Boxes.--Pistons, Piston Rods, Crossheads, and Slide Bars.
    --Connecting and Coupling Rods.--Wheels and Axles, Axle Boxes,
    Hornblocks, and Bearing Springs.--Balancing.--Valve Gear.--Slide
    Valves and Valve Gear Details.--Framing, Bogies and Axle Tracks,
    Radial Axle Boxes.--Boilers.--Smokebox, Blast Pipe, Firebox
    Fittings.--Boiler Mountings.--Tenders.--Railway Brakes.--
    Lubrication.--Consumption of Fuel, Evaporation and Engine
    Efficiency.--American Locomotives.--Continental Locomotives.--
    Repairs, Running, Inspection, and Renewals.--Three Appendices.--
    Index.

    “The work CONTAINS ALL THAT CAN BE LEARNT from a book upon such a
    subject. It will at once rank as THE STANDARD WORK UPON THIS
    IMPORTANT SUBJECT.”--_Railway Magazine._

                      *       *       *       *       *

                  AT PRESS. In Large 8vo. Fully Illustrated.

                  =LOCOMOTIVE COMPOUNDING AND SUPERHEATING.=

                              By J. F. GAIRNS.

    CONTENTS.--Introductory.--Compounding and Superheating for
    Locomotives.--A Classification of Compound Systems for
    --The History and Development of the Compound Locomotives.
    Locomotive.--Two-Cylinder Non-Automatic Systems.--Two-Cylinder
    Automatic Systems.--Other Two-Cylinder Systems.--Three-Cylinder
    Systems.--Four-Cylinder Tandem Systems.--Four-Cylinder
    Two-Crank Systems (other than Tandem).--Four-Cylinder Balanced
    Systems.--Four-Cylinder Divided and Balanced Systems.--Articulated
    Compound Engines.--Triple-Expansion Locomotives.--Compound Rack
    Locomotives.--Concluding Remarks Concerning Compound Locomotives.
    --The Use of Superheated Steam for Locomotives.--Index.

                      *       *       *       *       *

     _In Large 8vo. Handsome Cloth. With Plates and Illustrations.  16s._

                      *       *       *       *       *

                                LIGHT RAILWAYS
                              AT HOME AND ABROAD.

                      By WILLIAM HENRY COLE, M.Inst.C.E.,

               Late Deputy-Manager, North-Western Railway, India.

    _Contents._--Discussion of the Term “Light Railways.”--English
    Railways, Rates, and Farmers.--Light Railways in Belgium, France,
    Italy, other European Countries, America and the Colonies, India,
    Ireland.--Road Transport as an alternative.--The Light Railways Act,
    1896.--The Question of Gauge.--Construction and Working.--
    Locomotives and Rolling-Stock.--Light Railways in England, Scotland,
    and Wales.--Appendices and Index.

    “Will remain, for some time yet a Standard Work in everything
    relating to Light Railways.”--_Engineer._

    “The whole subject is EXHAUSTIVELY and PRACTICALLY considered.
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    whose duty it is to become acquainted with one of the prime
    necessities of the immediate future.”--_Railway Official Gazette._

                      *       *       *       *       *

      LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

          Fourth Edition, Thoroughly Revised and Greatly Enlarged.
               _With Numerous Illustrations. Price 10s. 6d_.

                         VALVES AND VALVE-GEARING:
                    A PRACTICAL TEXT-BOOK FOR THE USE OF
                    ENGINEERS, DRAUGHTSMEN, AND STUDENTS.

                   By CHARLES HURST, Practical Draughtsman.

    PART I.--Steam Engine Valves.

    PART II.--Gas Engine Valves and Gears.

    PART III.--Air Compressor Valves and Gearing.

    PART IV.--Pump Valves.

    “Mr. Hurst’s VALVES and VALVE-GEARING will prove a very valuable
    aid, and tend to the production of Engines of SCIENTIFIC DESIGN and
    ECONOMICAL working.... Will be largely sought after by Students and
    Designers.”--_Marine Engineer_.

    “Almost EVERY TYPE of VALVE and its gearing is clearly set forth,
    and illustrated in such a way as to be READILY UNDERSTOOD and
    PRACTICALLY APPLIED by either the Engineer, Draughtsman, or
    Student.... Should prove both USEFUL and VALUABLE to all Engineers
    seeking for RELIABLE and CLEAR Information on the subject. Its
    moderate price brings it within the reach of all.”--_Industries and
    Iron_.

                      *       *       *       *       *

    =HINTS ON STEAM ENGINE DESIGN AND CONSTRUCTION.= By CHARLES HURST,
      “Author of Valves and Valve Gearing.” SECOND EDITION, Revised.
      In Paper Boards, 8vo., Cloth Back. Illustrated. Price 1s. 6d. net.


    Contents.--I. Steam Pipes.--II. Valves.--III. Cylinders.--IV.
    Pumps and Condensers.--V. Motion Work.--VI. Crank Shafts and Air
    Pedestals.--VII. Valve Gear.--VIII. Lubrication.--IX. Miscellaneous
    Details.--Index.

     “A handy volume which every practical young engineer should
     possess.” --_The Model Engineer_.

                      *       *       *       *       *

        Strongly Bound in Super Royal 8vo. Cloth Boards. 7s. 6d. net.

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                       By HENRY A. GOLDING, A.M.Inst.M.E.,

          Technical Assistant to Messrs. Bryan Donkin and Clench, Ltd.,
       and Assistant Lecturer in Mechanical Engineering at the Northampton
                             Institute, London, E.C.

    “Cannot fail to prove practically serviceable to those for whom they
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                      *       *       *       *       *

        Second Edition, Cloth, 8s. 6d. Leather, for the Pocket, 8s. 6d.

    =GRIFFIN’S ELECTRICAL PRICE-BOOK:= For Electrical, Civil, Marine,
       and Borough Engineers, Local Authorities, Architects, Railway
       Contractors, &c., &c. Edited by H. J. Dowsing.

    “The Electrical Price-book REMOVES ALL MYSTERY about the cost of
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    utilising electricity on a large or small scale can be discovered.”
    --_Architect_.

                           =By WILLIAM NICHOLSON.=

                      *       *       *       *       *

                               =SMOKE ABATEMENT.=
                                (_See page 76_.)

                      *       *       *       *       *

       =LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.=

                      *       *       *       *       *

          Shortly. Second Edition. Large 8vo, Handsome Cloth. With
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                          LUBRICATION & LUBRICANTS:
                              A TREATISE ON THE
                     =THEORY AND PRACTICE OF LUBRICATION=
                                 AND ON THE
                NATURE, PROPERTIES, AND TESTING OF LUBRICANTS.

                   By LEONARD ARCHBUTT, F. I. C., F. C. S.,
                   Chemist to the Midland Railway Company,

                                     AND

                   R. MOUNTFORD DEELEY, M.I.Mech.E., F.G.S.,
           Chief Locomotive Superintendent, Midland Railway Company.

    Contents.--I. Friction of Solids.--II. Liquid Friction or Viscosity,
    and Plastic Friction.--III. Superficial Tension.--IV. The Theory of
    Lubrication.--V. Lubricants, their Sources, Preparation, and
    Properties.--VI. Physical Properties and Methods of Examination of
    Lubricants.--VII. Chemical Properties and Methods of Examination of
    Lubricants.--VIII. The Systematic Testing of Lubricants by Physical
    and Chemical Methods.--IX. The Mechanical Testing of Lubricants.
    --X. The Design and Lubrication of Bearings.--XI. The Lubrication of
    Machinery.--Index.

    “Destined to become a CLASSIC on the subject.”--_Industries and
    Iron._

    “Contains practically ALL THAT IS KNOWN on the subject. Deserves the
    careful attention of all Engineers.”--_Railway Official Guide._

                      *       *       *       *       *

            Fourth Edition. _Very fully Illustrated. Cloth, 4s. 6d._

                                STEAM-BOILERS:
              =THEIR DEFECTS, MANAGEMENT, AND CONSTRUCTION.=

                                By R. D. MUNRO,
    _Chief Engineer of the Scottish Boiler Insurance and Engine
    Inspection Company._

    General Contents.--i. Explosions caused (1) by Overheating of Plates
    --(2) By Defective and Overloaded Safety Valves--(3) By Corrosion,
    Internal or External--(4) By Defective Design and Construction
    (Unsupported Flue Tubes; Unstrengthened Manholes; Defective Staying;
    Strength of Rivetted Joints; Factor of Safety)--II. Construction Of
    Vertical Boilers:  Shells--Crown Plates and Uptake Tubes--Man-Holes,
    Mud-Holes, and Fire-Holes--Fireboxes--Mountings--Management--
    Cleanings--Table of Bursting Pressures of Steel Boilers--Table of
    Rivetted Joints--Specifications and Drawings of Lancashire Boiler
    for Working Pressures (_a_) 80 lbs.; (_b_) 200 lbs. per square inch
    respectively.

    “A valuable companion for workmen and engineers engaged about Steam
    Boilers, ought to be carefully studied, and ALWAYS AT HAND.”
    --_Coll. Guardian_.

    “The book is VERY USEFUL, especially to steam users, artisans, and
    young Engineers.”--_Engineer_.

                      *       *       *       *       *

                              By THE SAME AUTHOR.

    =KITCHEN BOILER EXPLOSIONS:= Why they Occur, and How to Prevent
    their Occurrence. A Practical Handbook based on Actual Experiment.
    With Diagram and  Plate. Price 3s.

                      *       *       *       *       *

     =LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.=

                      *       *       *       *       *

              _In Crown 8vo, Cloth. Fully Illustrated. 5s. net_.

                           EMERY GRINDING MACHINERY.

    A Text-Book of Workshop Practice in General Tool Grinding, and
    the Design, Construction, and Application of the Machines Employed.

                       By R. B. HODGSON, A.M.Inst.mech.E.

     Introduction.--Tool Grinding.--Emery Wheels.--Mounting Emery
     Wheels.--Emery Rings and Cylinders.--Conditions to Ensure Efficient
     Working.--Leading Types of Machines.--Concave and Convex Grinding.
     --Cup and Cone Machines.--Multiple Grinding.--“Guest” Universal and
     Cutter Grinding Machines.--Ward Universal Cutter Grinder.--Press.
     --Tool Grinding.--Lathe Centre Grinder.--Polishing.--Index.

     “Eminently practical ... cannot fail to attract the notice of the
     users of this class of machinery, and to meet with careful
     perusal.”--_Chem. Trade Journal_.

                      *       *       *       *       *

      IN THREE PARTS. Crown 8vo, Handsome Cloth. Very Fully Illustrated.

                      MOTOR-CAR MECHANISM AND MANAGEMENT.

                        By W. POYNTER ADAMS, M.INST.E.E.

                                 IN THREE PARTS.

              Part I.--The Petrol Car. Part II.--The Electrical Car.

                             Part III.--The Steam Car.

                        =PART I.--THE PETROL CAR.= 5s. net.

    =Contents.=--Section I.--The Mechanism of the Petrol Car.--The
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    Accessories.--Multiple Cylinder Engines.--The Petrol.--The Chassis
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    --The Engine.--The Engine Accessories.--Electrical Ignition.--The
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                      *       *       *       *       *

                Sixth Edition. Folio, strongly half-bound, 21s.

                               TRAVERSE TABLES:

      Computed to Four Places of Decimals for every Minute of Angle up
                              to 100 of Distance.

                   For the Use of Surveyors and Engineers.

                            By RICHARD LLOYD GURDEN,
       Authorised Surveyor for the Governments of New South Wales and
                                    Victoria.

    =⁂= _Published with the Concurrence of the Surveyors-General for
                         New South Wales and Victoria_.

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                      *       *       *       *       *

       LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

                                  WORKS BY
              ANDREW JAMIESON, M.Inst.C.E., M.I.E.E., F.R.S.E.,
      _Formerly Professor of Electrical Engineering, The Glasgow and
                     West of Scotland Technical College_.

                      *       *       *       *       *

                   PROFESSOR JAMIESON’S ADVANCED TEXT-BOOKS.

                    _In Large Crown 8vo. Fully Illustrated_.

    STEAM AND STEAM-ENGINES, INCLUDING TURBINES AND BOILERS. For
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    “Professor Jamieson fascinates the reader by his CLEARNESS OF
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    “The BEST BOOK yet published for the use of Students.”--_Engineer_.


    APPLIED MECHANICS & MECHANICAL ENGINEERING.
      Vol. I.--Comprising Part I., with 568 pages, 300 Illustrations,
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    “Fully MAINTAINS the reputation of the Author.”--_Pract. Engineer_.

      Vol. II.--Comprising Parts III. to VI., with 782 pages, 371
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    “Well AND LUCIDLY WRITTEN.”--The Engineer.

      =⁂= _Each of the above volumes is complete in itself, and sold
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                      *       *       *       *       *

                  PROFESSOR JAMIESON’S INTRODUCTORY MANUALS

            _Crown 8vo. With Illustrations and Examination Papers_.

    STEAM AND THE STEAM-ENGINE (Elementary Manual of). For First-Year
      Students. Eleventh Edition, Revised. 3/6.

      “Should be in the hands of EVERY engineering apprentice.”
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    MAGNETISM AND ELECTRICITY (Elementary Manual of).
      For First-Year Students. Seventh Edition. 3/6.

      “A CAPITAL TEXT-BOOK.... The diagrams are an important feature.”
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      “A THOROUGHLY TRUSTWORTHY Text-book. Practical and clear.”
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    APPLIED MECHANICS (Elementary Manual of).
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      “The work has VERY HIGH QUALITIES, which may be condensed into
      the one word ‘CLEAR.’”--_Science and Art_.

                      *       *       *       *       *

    A POCKET-BOOK of ELECTRICAL RULES and TABLES.
      For the Use of Electricians and Engineers. By JOHN MUNRO, C.E.,
      and Prof. JAMIESON. Pocket Size. Leather, 8s. 6d. SEVENTEENTH
      EDITION. [See p. 48.]

                      *       *       *       *       *

        LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

                                   WORKS BY

                     W. J. MACQUORN RANKINE, LL.D., F.R.S.,

    _Late Regius Professor of Civil Engineering in the University of
                                   Glasgow_.

                             THOROUGHLY REVISED BY

                               W. J. MILLAR, C.E.,

    _Late Secretary to the Institute of Engineers and Shipbuilders
                                  in Scotland_.

                      *       *       *       *       *

                        A MANUAL OF APPLIED MECHANICS:

    Comprising the Principles of Statics and Cinematics, and Theory
        of Structures, Mechanism, and Machines. With Numerous Diagrams.
        Crown 8vo, cloth. SEVENTEENTH EDITION. 12s. 6d.

                      *       *       *       *       *

                        A MANUAL OF CIVIL ENGINEERING:

    Comprising Engineering Surveys, Earthwork, Foundations, Masonry,
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        Waterworks, Harbours, &c. With Numerous Tables and
        Illustrations. Crown 8vo. cloth. TWENTY-SECOND EDITION. 16s.

                      *       *       *       *       *

                      A MANUAL OF MACHINERY AND MILLWORK:

    Comprising the Geometry, Motions, Work, Strength, Construction,
        and Objects of Machines, &c. Illustrated with nearly 300
        Woodcuts, Crown 8vo, cloth. Seventh Edition. 12s. 6d.

                      *       *       *       *       *

             A MANUAL OF THE STEAM-ENGINE AND OTHER PRIME MOVERS:

    With a Section on Gas, Oil, and Air Engines, by Bryan Donkin,
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                      *       *       *       *       *

        LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

    PROF. RANKINE’S WORKS--(_Continued_).

                          USEFUL RULES AND TABLES:

    For Architects, Builders, Engineers, Founders, Mechanics,
      Shipbuilders, Surveyors, &c. With Appendix for the use of
      Electrical Engineers. By Professor Jamieson, F.R.S.E.
      Seventh Edition. 10s. 6d.

                      *       *       *       *       *

                           A MECHANICAL TEXT-BOOK:

    A Practical and Simple Introduction to the Study of Mechanics.
      By Professor Rankine and E. F. Bamber, C.E. With Numerous
      Illustrations. Crown 8vo, cloth. Fifth Edition. 9s.

    =⁂= _The_ “Mechanical Text-book” _was designed by_ Professor
    Rankine as an Introduction _to the above Series of Manuals_.

                      *       *       *       *       *

                       MISCELLANEOUS SCIENTIFIC PAPERS.

                          Royal 8vo. Cloth, 31s. 6d.

    Part I. Papers relating to Temperature, Elasticity, and
    Expansion of Vapours, Liquids, and Solids. Part II. Papers on Energy
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    of Vessels, &c.

    With Memoir by Professor TAIT, M.A. Edited by W. J. Millar, C.E.
    With fine Portrait on Steel, Plates, and Diagrams.

    “No more enduring Memorial of Professor Rankine could be devised
    than the publication of these papers in an accessible form....
    The Collection is most valuable on account of the nature of his
    discoveries, and the beauty and completeness of his analysis....
    The Volume exceeds in importance any work in the same department
    published in our time.”--_Architect_.

                      *       *       *       *       *

          By W. VINCENT SHELTON (Foreman to the Imperial Ottoman Gun
                         Factories, Constantinople):

      THE MECHANIC’S GUIDE: A Hand-Book for Engineers and Artizans.
      With Copious Tables and Valuable Recipes for Practical Use.
      Illustrated. _Second Edition_. Crown 8vo. Cloth, 7/6.

                      *       *       *       *       *

       LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND

                      *       *       *       *       *

       Third Edition, _Thoroughly Revised and Enlarged. With 60 Plates
              and Numerous Illustrations. Handsome Cloth_. 34s.

                               HYDRAULIC POWER

                                     AND

                              HYDRAULIC MACHINERY.

                                      BY

                     HENRY ROBINSON, M. Inst. C.E., F.G.S.,

            FELLOW OF KING’S COLLEGE, LONDON; PROF. EMERITUS OF CIVIL
                     ENGINEERING, KING’S COLLEGE, ETC., ETC.

    Contents.--Discharge through Orifices.--Flow of Water through
    Pipes.--Accumulators.--Presses and Lifts.--Hoists.--Rams.--Hydraulic
    Engines.--Pumping Engines.--Capstans.--Traversers.--Jacks.--Weighing
    Machines.--Riveters and Shop Tools.--Punching, Shearing, and
    Flanging Machines.--Cranes.--Coal Discharging Machines.--Drills and
    Cutters.--Pile Drivers, Excavators, &c.--Hydraulic Machinery applied
    to Bridges, Dock Gates, Wheels and Turbines.--Shields.--Various
    Systems and Power Installations.--Meters, &c.--Index.

    “The standard work on the application of water power.”--_Cassier’s
    Magazine_.

                      *       *       *       *       *

        _Second Edition, Greatly Enlarged. With Frontispiece, several
               Plates, and over 250 Illustrations_. 21_s. net._

                     THE PRINCIPLES AND CONSTRUCTION OF

                              PUMPING MACHINERY

                         (STEAM AND WATER PRESSURE).

    With Practical Illustrations of Engines and Pumps applied to Mining,
          Town Water Supply, Drainage of Lands, &c., also Economy
                  and Efficiency Trials of Pumping Machinery.

                             By HENRY DAVEY,

        Member of the Institution of Civil Engineers, Member of the
              Institution of Mechanical Engineers, F.G.S., &c.

    Contents--Early History of Pumping Engines--Steam Pumping Engines--
    Pumps and Pump Valves--General Principles of Non-Rotative Pumping
    Engines--The Cornish Engine, Simple and Compound--Types of Mining
    Engines--Pit Work--Shaft Sinking--Hydraulic Transmission of Power in
    Mines--Electric Transmission of Power--Valve Gears of Pumping
    Engines--Water Pressure Pumping Engines--Water Works Engines--
    Pumping Engine Economy and Trials of Pumping Machinery--Centrifugal
    and other Low-Lift Pumps--Hydraulic Rams, Pumping Mains, &c.--Index.

    “By the ‘one English Engineer who probably knows more about Pumping
    Machinery than ANY OTHER.’ ... A VOLUME RECORDING THE RESULTS OF
    LONG EXPERIENCE AND STUDY.”--_The Engineer_.

    “Undoubtedly THE BEST AND MOST PRACTICAL TREATISE on Pumping
    Machinery THAT HAS YET BEEN PUBLISHED.”--_Mining Journal_.

                      *       *       *       *       *

        LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

    _Royal 800, Handsome Cloth. With numerous Illustrations and Tables.
    25s._

                            THE STABILITY OF SHIPS.
                                      BY

                    SIR EDWARD J. REED, K.C.B., F.R.S., M.P.,

    KNIGHT OF THE IMPERIAL ORDERS OF ST. STANILAUS OF RUSSIA;
    FRANCIS JOSEPH OF AUSTRIA; MEDJIDIE OF TURKEY; AND RISING SUN OF
    JAPAN; VICE-PRESIDENT OF THE INSTITUTION OF NAVAL ARCHITECTS.

    “Sir Edward Reed’s ‘Stability of Ships’ is INVALUABLE. The Naval
    Architect will find brought together and ready to his hand, a mass
    of information which he would otherwise have to seek in an almost
    endless variety of publications, and some of which he would possibly
    not be able to obtain at all elsewhere.”--_Steamship_.

                      *       *       *       *       *

    THE DESIGN AND CONSTRUCTION OF SHIPS. By JOHN HARVARD BILES,
      M.Inst.N.A., Professor of Naval Architecture in the University of
      Glasgow.                                       [_In Preparation_.]

                      *       *       *       *       *

      Third Edition. Illustrated with Plates, Numerous Diagrams, and
                        Figures in the Text. 18s. net.

                                 STEEL SHIPS:
                     THEIR CONSTRUCTION AND MAINTENANCE.
         _A Manual for Shipbuilders, Ship Superintendents, Students,
                              and Marine Engineers_.

                        By THOMAS WALTON, Naval Architect,
                          Author of “Know Your Own Ship.”

    Contents.--I. Manufacture of Cast Iron, Wrought Iron, and Steel.--
    Composition of Iron and Steel, Quality, Strength, Tests, &c. II.
    Classification of Steel Ships. III. Considerations in making choice
    of Type of Vessel.--Framing of Ships. IV. Strains experienced by
    Ships.--Methods of Computing and Comparing Strengths of Ships. V.
    Construction of Ships.--Alternative Modes of Construction.--Types
    of Vessels.--Turret, Self Trimming, and Trunk Steamers, &c.--Rivets
    and Rivetting, Workmanship. VI. Pumping Arrangements. VII.
    Maintenance.--Prevention of Deterioration in the Hulls of Ships.
    --Cement, Paint, &c.--Index.

    “So thorough and well written is every chapter in the book that it
    is difficult to select any of them as being worthy of exceptional
    praise. Altogether, the work is excellent, and will prove of great
    value to those for whom it is intended.”--The Engineer.

                      *       *       *       *       *

             AT PRESS. In Handsome Cloth. Very fully Illustrated.

                           PRESENT-DAY SHIPBUILDING.

           _For Shipyard Students, Ships’ Officers, and Engineers._

                               By THOS. WALTON,

                        Author of “Know Your Own Ship.”

    General Contents.--Classification.--Materials used in Shipbuilding.
    --Alternative Modes of Construction.--Details of Construction.--
    Framing, Plating, Rivetting, Stem Frames, Twin-Screw Arrangements,
    Water Ballast Arrangements, Loading and Discharging Gear, &c.--Types
    of Vessels, including Atlantic Liners, Cargo Steamers, Oil carrying
    Steamers, Turret and other Self Trimming Steamers, &c.--Index.

                      *       *       *       *       *

        LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

                           GRIFFIN’S NAUTICAL SERIES.

                            Edited by EDW. BLACKMORE,

        Master Mariner, First Class Trinity House Certificate, Assoc.
           Inst. N.A.; And Written, MAINLY, by Sailors for Sailors.

                      *       *       *       *       *

    “This ADMIRABLE SERIES.”--_Fairplay_. “A VERY USEFUL SERIES.”--
    _Nature_.

    “Every Ship should have the WHOLE SERIES as a Reference Library.
    Handsomely Bound, CLEARLY PRINTED and ILLUSTRATED.”--_Liverpool
    Journ. of Commerce_.

                      *       *       *       *       *

    The British Mercantile Marine: An Historical Sketch of its Rise
      and Development. By the Editor, Capt. Blackmore. 3s. 6d.

    “Captain Blackmore’s SPLENDID BOOK ... contains paragraphs on
    every point of interest to the Merchant marine. The 243 pages of
    this book are THE MOST VALUABLE to the sea captain that have EVER
    been COMPILED.”--_Merchant Service Review_.

                      *       *       *       *       *

    Elementary Seamanship. By D. Wilson-barker, Master Mariner,
      F.R.S.E., F.R.G.S. With numerous Plates, two in Colours, and
      Frontispiece.

    Fourth Edition, Thoroughly Revised. With additional Illustrations.
      6s.

    “This ADMIRABLE MANUAL, by Capt. Wilson Barker, of the ‘Worcester,’
      seems to us PERFECTLY DESIGNED.”--_Athenæum_.

                      *       *       *       *       *

    KNOW YOUR OWN SHIP: A Simple Explanation of the Stability,
      Construction, Tonnage, and Freeboard of Ships. By THOS. WALTON,
      Naval Architect.

      With numerous Illustrations and additional Chapters on Buoyancy,
      Trim, and Calculations. NINTH EDITION. 7s. 6d.

      “MR. WALTON’S book will be found VERY USEFUL.”--_The Engineer_.

                      *       *       *       *       *

    Navigation: Theoretical and Practical. By D. Wilson-Barker and
      William Allingham. Second Edition, Revised. 3s. 6d.

      “Precisely the kind of work required for the New Certificates of
      competency.

    Candidates will find it INVALUABLE.”--_Dundee Advertiser_.

                      *       *       *       *       *

    Marine Meteorology: For Officers of the Merchant Navy. By
      WILLIAM ALLINGHAM, First Class Honours, Navigation, Science and
      Art Department.

      With Illustrations, Maps, and Diagrams, and _facsimile_
      reproduction of log page. 7s. 6d.

      “Quite the BEST PUBLICATION on this subject.”--_Shipping
      Gazette_.

                      *       *       *       *       *

    Latitude and Longitude: How to Find Them. By W. J. Millar, C.E.
      Second Edition, Revised. 2s.

      “Cannot but prove an acquisition to those studying Navigation.”
      --_Marine Engineer_.

                      *       *       *       *       *

    Practical Mechanics: Applied to the requirements of the Sailor.
      By Thos. Mackenzie, Master Mariner, F.R.A.S. Second Edition,
      Revised. 3s. 6d.

      “Well Worth the money ... EXCEEDINGLY HELPFUL.”--_Shipping
      World_.

                      *       *       *       *       *

    Trigonometry: For the Young Sailor, &c. By Rich. C. Buck, of the
      Thames Nautical Training College, H.M.S. “Worcester.” Third
      Edition, Revised. Price 3s. 6d.

      “This EMINENTLY PRACTICAL and reliable volume.”--_Schoolmaster_.

                      *       *       *       *       *

    Practical Algebra. By Rich. C. Buck. Companion Volume to the
      above, for Sailors and others. SECOND EDITION, Revised. Price
      3s. 6d.

      “It is JUST THE BOOK for the young sailor mindful of
      progress.”--_Nautical Magazine_.

                      *       *       *       *       *

    The Legal Duties of Shipmasters. By Benedict Wm. Ginsburg, M.A.,
      LL.D., of the Inner Temple and Northern Circuit: Barrister-at-Law.
      Second Edition, Thoroughly Revised and Enlarged. Price 4s. 6d.

      “Invaluable to masters.... We can fully recommend it.”
      --_Shipping Gazette_.

                      *       *       *       *       *

    A Medical and Surgical Help For Shipmasters. Including First Aid
      at Sea. By WM. JOHNSON SMITH, F.R.C.S., Principal Medical Officer,
      Seamen’s Hospital, Greenwich. THIRD EDITION, Thoroughly Revised.
      6s.

      “SOUND, JUDICIOUS, REALLY HELPFUL.”--_The Lancet_.

                      *       *       *       *       *

        LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

                          GRIFFIN’S NAUTICAL SERIES.

                   _Introductory Volume_. _Price_ 3_s_. 6_d_.

                                     THE

                           British Mercantile Marine.

                               BY EDWARD BLACKMORE,

       MASTER MARINER; ASSOCIATE OF THE INSTITUTION OF NAVAL ARCHITECTS;

          MEMBER OF THE INSTITUTION OF ENGINEERS AND SHIPBUILDERS IN
               SCOTLAND; EDITOR OF GRIFFIN’S “NAUTICAL SERIES.”

    General Contents.--Historical: From Early Times to 1486--Progress
    under Henry VIII.--To Death of Mary--During Elizabeth’s Reign--Up to
    the Reign of William III.--The 18th and 19th Centuries--Institution
    of Examinations--Rise and Progress of Steam Propulsion--Development
    of Free Trade--Shipping Legislation, 1862 to 1875--“Locksley Hall”
    Case--Shipmasters’ Societies--Loading of Ships--Shipping
    Legislation, 1884 to 1894--Statistics of Shipping. The Personnel:
    Shipowners--Officers--Mariners--Duties and Present Position.
    Education: A Seaman’s Education: what it should be--Present Means of
    Education--Hints. Discipline and Duty--Postscript--The Serious
    Decrease in the Number of British Seamen, a Matter demanding the
    Attention of the Nation.

    “Interesting and Instructive ... may be read WITH PROFIT and
    ENJOYMENT.”--_Glasgow Herald_.

    “Every Branch of the subject is dealt with in a way which shows that
    the writer ‘knows the ropes’ familiarly.”--_Scotsman_.

    “This ADMIRABLE book ... TEEMS with useful information--Should
    be in the hands of every Sailor.”--_Western Morning News_.

                      *       *       *       *       *

            Fourth Edition, _Thoroughly Revised. With Additional
                          Illustrations. Price_ 6_s_.

                                 A MANUAL OF

                            ELEMENTARY SEAMANSHIP.
                                      BY

       D. WILSON-BARKER, Master Mariner; F.R.S.E., F.R.G.S., &c., &c.
                     YOUNGER BROTHER OF THE TRINITY HOUSE.

           With Frontispiece, Numerous Plates (Two in Colours), and
                           Illustrations in the Text.

    General Contents.--The Building of a Ship; Parts of Hull, Masts, &c.
    --Ropes, Knots, Splicing, &c.--Gear, Lead and Log, &c.--Rigging,
    Anchors--Sailmaking--The Sails, &c.--Handling of Boats under Sail
    --Signals and Signalling--Rule of the Road--Keeping and Relieving
    Watch--Points of Etiquette--Glossary of Sea Terms and Phrases
    --Index.

             =⁂= The volume contains the NEW RULES OF THE ROAD.

    “This ADMIRABLE MANUAL, by Capt. Wilson-Barker of the ‘Worcester,’
    seems to us PERFECTLY DESIGNED, and holds its place excellently in
    ‘GRIFFIN’S NAUTICAL SERIES.’ ... Although intended for those who are
    to become Officers of the Merchant Navy, it will be found useful by
    ALL YACHTSMEN.”--_Athenæum_.

     =⁂= For complete List of GRIFFIN’S NAUTICAL SERIES, see p. 39.

                      *       *       *       *       *

      LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

                         _GRIFFIN’S NAUTICAL SERIES._

          Second Edition, _Revised and Illustrated. Price 3s. 6d._

                                 NAVIGATION:

                          PRACTICAL AND THEORETICAL.

            By DAVID WILSON-BARKER, R.N.R., F.R.S.E., &c., &c.,

                                     AND

                             WILLIAM ALLINGHAM,

        FIRST-CLASS HONOURS, NAVIGATION, SCIENCE AND ART DEPARTMENT.

           With Numerous Illustrations and Examination Questions.

    General Contents.--Definitions--Latitude and Longitude--Instruments
    of Navigation--Correction of Courses--Plane Sailing--Traverse
    Sailing--Day’s Work--Parallel Sailing--Middle Latitude Sailing--
    Mercator’s Chart--Mercator Sailing--Current Sailing--Position by
    Bearings--Great Circle Sailing--The Tides--Questions--Appendix:
    Compass Error--Numerous Useful Hints, &c.--Index.

    “Precisely the kind of work required for the New Certificates of
    competency in grades from Second Mate to extra Master.... Candidates
    will find it INVALUABLE.”--_Dundee Advertiser._

    “A CAPITAL LITTLE BOOK ... specially adapted to the New
    Examinations. The Authors are Capt. Wilson-barker (Captain-
    Superintendent of the Nautical College, H.M.S. ‘Worcester,’ who has
    had great experience in the highest problems of Navigation), and Mr.
    Allingham, a well-known writer on the Science of Navigation and
    Nautical Astronomy.”--_Shipping World._

                      *       *       *       *       *

              _Handsome Cloth. Fully Illustrated. Price 7s. 6d._

                             MARINE METEOROLOGY,

                      FOR OFFICERS OF THE MERCHANT NAVY.

                             By WILLIAM ALLINGHAM,

            Joint Author of “Navigation, Theoretical and Practical.”

    With numerous Plates, Maps, Diagrams, and Illustrations, and a
    facsimile Reproduction of a Page from an actual Meteorological
    Log-Book.

                              SUMMARY OF CONTENTS.

    Introductory.--Instruments Used at Sea for Meteorological Purposes.
    --Meteorological Log-Books.--Atmospheric Pressure.--Air
    Temperatures.--Sea Temperatures.--Winds.--Wind Force Scales.--
    History of the Law of Storms.--Hurricanes, Seasons, and Storm
    Tracks.--Solution of the Cyclone Problem.--Ocean Currents.--
    Icebergs.--Synchronous Charts.--Dew, Mists, Fogs, and Haze.--Clouds.
    --Rain, Snow, and Hail.--Mirage, Rainbows, Coronas, Halos, and
    Meteors.--Lightning, Corposants, and Auroras.--Questions.--appendix.
    --Index.

    “Quite the BEST publication, AND certainly the MOST INTERESTING,
    on this subject ever presented to Nautical men.”--_Shipping Gazette._

       =⁂= For Complete List of GRIFFIN’S NAUTICAL SERIES, see p. 39.

                      *       *       *       *       *

       LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                      *       *       *       *       *

                          GRIFFIN’S NAUTICAL SERIES.

    Second Edition, Revised. With Numerous Illustrations. Price 3s. 6d.

                             Practical Mechanics:

                  Applied to the Requirements of the Sailor.

                              BY THOS. MACKENZIE,

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                      *       *       *       *       *

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                      *       *       *       *       *

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                      *       *       *       *       *

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                      *       *       *       *       *

         Just Out. In Large 8vo. Profusely Illustrated. 8s. 6d. net.

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                      *       *       *       *       *

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                      *       *       *       *       *

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                      *       *       *       *       *

                       GRIFFIN’S ELECTRICAL PRICE-BOOK.

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                      *       *       *       *       *

       Third Edition, Revised, Enlarged, and Re-issued. Price 6s. net.

                              A SHORT MANUAL OF
                             INORGANIC CHEMISTRY.

                                      BY
                            A. DUPRÉ, Ph.D., F.R.S.,

                                      AND

                       WILSON HAKE, Ph.D., F.I.C., F.C.S.,
                   Of the Westminster Hospital Medical School.

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                      *       *       *       *       *

                  LABORATORY HANDBOOKS BY A. HUMBOLDT SEXTON,
                           Professor of Metallurgy
             in the Glasgow and West of Scotland Technical College.

                      *       *       *       *       *

                      OUTLINES OF QUANTITATIVE ANALYSIS.

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                      *       *       *       *       *

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                      *       *       *       *       *

                            ELEMENTARY METALLURGY:

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              GRIFFIN’S CHEMICAL AND TECHNOLOGICAL PUBLICATIONS.

                                                                  PAGE
    Inorganic Chemistry,           Profs. Dupré and Hake,          50
    Quantitative Analysis,         Prof. Humboldt Sexton,          50
    Qualitative      ”                     ”         ”             50
    Chemistry For Engineers,       Blount and Bloxam,              46
        ”      ”   Manufacturers,     ”         ”                  71
    Foods and Poisons,             a. Wynter Blyth,                72
    Tables For Chemists,           Prof. Castell-evans,            79
    Dairy Chemistry,               H. D. Richmond,                 73
    Dairy Analysis,                         ”                      73
    Milk,                          E. F. Willoughby,               73
    Flesh Foods,                   C. a. Mitchell,                 74
    Practical Sanitation,          Dr. G. Reid,                    78
    Sanitary Engineering,          F. Wood,                        78
    Technical Mycology,            Lafar and Salter,               74
    Ferments,                      C. Oppenheimer,                 75
    Toxines and Anti-toxines,             ”    ”                   74
    Brewing,                       Dr. W. J. Sykes,                75
    Bacteriology of Brewing,       W. a. Riley,                    75
    Sewage Disposal,               Santo Crimp,                    47
    Trades’ Waste,                 W. Naylor,                      47
    Smoke Abatement,               Wm. Nicholson,                  47
    Paper Technology,              R. W. Sindall,                  81
    Cements,                       G. R. Redgrave,                 47
    Water Supply,                  R. E. Middleton,                77
    Road Making,                   Thos. Aitken,                   79
    Gas Manufacture,               W. Atkinson Butterfield,        77
    Acetylene,                     Leeds and Butterfield,          77
    Fire Risks,                    Dr. Schwartz,                   77
    Petroleum,                     Sir Boverton Redwood,           61
    ---- (Handbook),               Thomson and Redwood,            61
    Ink Manufacture,               Mitchell and Hepworth,          81
    Glue, Gelatine, &c.,           Thos. Lambert,                  81
    Oils, Soaps, Candles,          Wright & Mitchell,              71
    Lubrication & Lubricants,      Archbutt and Deeley,            32
    India Rubber,                  Dr. Carl O. Weber,              81
    Painters’ Colours, Oils, &c.,  G. H. Hurst,                    80
    Painters’ Laboratory Guide,       ”     ”                      80
    Painting and Decorating,       W. J. Pearce,                   80
    Dyeing,                        Knecht and Rawson,              82
    Dictionary of Dyes,            Rawson and Gardner,             82
    the Synthetic Dyestuffs,       Cain and Thorpe,                82
    Spinning,                      H. R. Carter,                   83
    Textile Printing,              Seymour Rothwell,               83
    Textile Fibres of Commerce,    W. I. Hannan,                   83
    Dyeing and Cleaning,           G. H. Hurst,                    84
    Bleaching, Calico-printing,    Geo. Duerr,                     84

                      *       *       *       *       *

        LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.

                Griffin’s Geological, Prospecting, Mining, and
                          Metallurgical Publications.
                                                                  Page
    Geology, Stratigraphical,      R. Etheridge, F.R.S.,           52
       ”     Physical,             Prof. H. G. Seeley,             52
       ”     Practical Aids,       Prof. Grenville Cole,           53
       ”     Open Air Studies,             ”         ”             19
      Mining Geology,              James Park, F.G.S.,             55
      Prospecting For Minerals,    S. Herbert Cox, A.R.S.M.,       55
      Food Supply,                 Robt. Bruce,                    54
      New Lands,                   H. R. Mill, D.SC., F.R.S.E.,    54
    Ore and Stone Mining,          Sir C. Lea Neve Foster,         56
      Elements of Mining,                   ”         ”            56
      Coal Mining,                 H. W. Hughes, F.G.S.,           56
      Practical Coal Mining,       G. L. Kerr, M.Inst.M.E.,        58
      Elementary    ”                     ”       ”                58
      Electrical Coal Mining,      D. Burns,                       58
    Mine-surveying,                Bennett H. Brough, A.R.S.M.,    57
    Mine Air, Investigation of,    Foster and Haldane,             57
    Mining Law,                    C. J. Alford,                   57
    Blasting and Explosives,       O. Guttmann, A.M.I.C.E.,        58
    Testing Explosives,            Bichel and Larsen,              58
    Mine Accounts,                 Prof. J. G. Lawn,               57
    Mining Engineers’ Pkt.-bk.,    E. R. Field, M.Inst.M.M.,       57
    Petroleum,                     Sir Boverton Redwood,           61
      A Handbook on Petroleum,     Thomson and Redwood,            61
      Oil Fuel,                    Sidney H. North,                29
    Metallurgical Analysis,        Macleod and Walker,             60
    Microscopic Analysis,          F. Osmond & J. E. Stead, F.R.S.,60
    Metallurgy (General),          Phillips and Bauerman,          60
        ”     (Elementary),        Prof. Humboldt Sexton,          66
      Getting Gold,                J. C. F. Johnson, F.G.S.,       59
      Gold Seeking in South Africa,theo Kassner,                   59
      Cyanide Process,             James Park, F.G.S.,             59
      Cyaniding,                   Julian and Smart,               59
      Electric Smelting,           Borchers and Mcmillan,          67
      Electro-metallurgy,          W. G. Mcmillan, F.I.C,          67
      Assaying,                    J. J. & C. Beringer,            66
      Metallurgical Analysis,      J. J. Morgan, F.C.S.,           66
    Metallurgy (Introduction to),  Sir W. Roberts-Austen, K.C.B.,  63
      Gold, Metallurgy of,         Dr. Kirke Rose, A.R.S.M.,       63
      Lead and Silver, ”           H. F. Collins, A.R.S.M.,        64
      Iron, Metallurgy of,         Thos. Turner, A.R.S.M.,         65
      Steel,     ”                 F. W. Harbord,                  65
    Iron-founding,                 Prof. Turner,                   68
    Precious Stones,               Dr. Max Bauer,                  68

                      *       *       *       *       *

      LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND.




    Transcriber’s Notes

    A few obvious misprints have been corrected (for example,
    “thorinum” for thorium), but in general the original spelling
    has been retained. Inconsistent use of hyphens and punctuation
    were left unchanged.

    The italics markup has been removed from table headings. Text
    appearing in small capitalisation has been converted to title case.





End of the Project Gutenberg EBook of Getting Gold, by J. C. F. Johnson

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