- . UNWERSnTg/mlFORNIA
1 COLLEGE o/- MINING
DEPARTMENTAL
LIBRARY
BEQUEST OF
SAMUELBENEDICTCHRISTY
PROFESSOR OF
MINING AND METALLURGY
1885-1914
BLOWPIPE ASSAYING
LONDON: 1'HINTED BY
SPOTTISWOOUK AND CO., XEW-STUKKT SQUAUK
AND PABMAJIEXT STBKKT
S. B. CHRISTY,
PEACTICAL
/
BLOWPIPE ASSAYING
BY
GEORGE ATTWOOD
\\
. S., ASSOC. INST. C.E., F.C.S., MEM. AM. INST. M.E., ETC,
NEW YORK
D. VAN NOSTRAND
23 MURRAY STREET
1881
/9s
PREFACE.
IN publishing this small volume of Practical Blowpipe
Assaying it is the wish of the Author to record the
methods of assaying adopted by himself during eighteen
years of foreign travel, in hopes that they will assist others
who have to make examinations where complete assay
offices and laboratories are not to be found.
Plattner's instruments and apparatus have been used
as much as possible ; but, as the methods here adopted
have in so many instances differed materially from those
of Plattner and other authorities on this subject, different
apparatus has been devised to suit the requirements.
The general system of assaying adopted is a simple
and a direct one. Sixty-four elements are mentioned
in this work, and the assayer may be asked to de-
termine the presence of one or all. The system being
a direct one, directions are laid down for the separate
determination of each. Practice will, however, soon en-
able the assayer to determine from one assay piece or
sample the presence of several elements instead of one,
and thereby save time and labour. For assaying, the
Author has always adopted the system of checking his
assays by synthetic assays, or, in other words, preparing
an assay with a weighed quantity of the chemically pure
metal or element to be determined, and mixing it with
30371 fi
vi PKEFACE.
materials resembling as nearly as possible those of the ore,
alloy, or compound to be assayed, and then, after the
completion of the assay, adding to the direct assay the
loss found to have been incurred in the synthetic.
In the assay of gold and silver alloys a check assay is
necessary. In silver assays it is absolutely necessary, and
by using the same most accurate results can be obtained.
Silver and gold coins, bars, and ingots can be valued or
stamped for market, and found to be correctly assayed, by
following the methods hereafter described.
, Whilst this little book has been going through the
press, my old friend, Professor John Morris, has, with
his usual kindness to all friends of science, assisted most
materially in the correction of the proof sheets and in the
revision of the work, and to him the Author now returns
his best thanks.
The following list of books has been used in the
preparation of this work, and in some cases material has
been drawn from them.
4, UPPER GLOUCESTER PLACE, N.W.
BOOKS CONSULTED IN THE PREPARATION OF
THIS WORK.
'A Manual of Practical Assaying.' By John Mitchell, F.C.S.
Edited by William Crookes, F.R.S. London, 1873.
' Plattner's Manual of Qualitative and Quantitative Analysis with
the Blowpipe.' By Professor Th. Richter. Translated by H. B.
Cornwall, A.M. , E.M. New York, 1873.
' A Manual of Metallurgy.' By George Hogarth Makins, M.R.C.S. ,
F.C.S. London, 1873.
'Chemical and Pharmaceutical Manipulations.' By Professor
Campbell Morfit and Clarence Morfit. Philadelphia, 1857.
' A Text-Book of Mineralogy. ' By Edward Salisbury Dana. New
York, 1877.
' Manual of Determinative Mineralogy. ' With an Introduction on
'Blowpipe Analysis.' By Professor George J. Brush. New
York, 1878.
'Elements of Metallurgy.' By J. Arthur Phillips, M. Inst. C.E.,
F.G.S., F.C.S., &c. London, 1874.
1 Determination of Minerals by the Blowpipe.' By Dr. C. W. C.
Fuchs. Translated and edited by F. W. Danby, M.A., F.G.S.
London.
'The Metallurgy of Silver and Lead.' By Robert H. Lamborn,
Ph.D. London, 1878.
' The Blowpipe : a Guide to its Use in the Determination of Salts
and Minerals.' By Professor George W. Plympton, C.E., &c.
New York, 1874.
' A System of Instruction in Quantitative Chemical Analysis.' By
Dr. C. Remigius Fresenius. London, 1860.
' Manual of Qualitative Chemical Analysis.' By Dr. C. Remigius
Fresenius. New York, 1864.
' Handbook of Chemistry.' By Professors F. A. Abel and C. L.
Bloxam.
' Chemical News.' David Forbes. Nos. 380, 384, 392, 396, 398,
and 412.
' Journal Chemical Society.' May 1879. Geo. Attwood on the
Assay of the Ores and Compounds of Mercury by the Blowpipe.
CONTENTS.
INTRODUCTION
PAGE
xiii
PAET I.
DESCRIPTION OF THE MOUTH BLOWPIPE AND
APPARATUS.
BLOWPIPE . . . .
HOW TO USE THE BLOWPIPE
BLOWPIPE FUEL . . .
LAMPS
FLAMES . . .
SUPPORTS .
WEIGHING IN-
STRUMENTS .
PAGE
3
7
10
12
17
BLOWPIPE TOOLS, SMALL IM-
PLEMENTS AND
APPARATUS . 22
BATEA . . . 29
REAGENTS, DRY
AND WET . 32
TEST OR PROOF
METALS 34
PART II.
Q UA LIT A TIVE DETERMINA TION.
COLOURS OF SUBLIMATES ON
CHARCOAL
POTASSIUM . . . .
SODIUM
C.ESIUM
RUBIDIUM .
BARIUM
STRONTIUM .
CALCIUM .
. . 49
43
MAGNESIUM .
. 50
45
ALUMINIUM
. . 52
46
MANGANESE .
. 52
47
TIN ....
. . 55
47
ANTIMONY .
. 55
47
SILVER
5G
48
GOLD
r,o
CONTEXTS.
PAGE I)AOK
CHROMIUM
. . 57
BORON
83
IRON
. 57
SILICIUM ....
83
COBALT
. . 61
GLUCINUM . . . .
84
NICKEL .
. 62
LANTHANUM
85
ZINC
. 63
YTTRIUM
C(\
CADMIUM
. 65
TERBIUM ....
oO
86
COPPER
. . 66
TANTALUM . . . .
86
LEAD
. 66
URANIUM ....
87
INDIUM
. . 68
TUNGSTEN . . . .
87
BISMUTH
. 68
VANADIUM ....
88
TITANIUM .
. . 69
PALLADIUM . . . .
88
MERCURY
. 71
RUTHENIUM
89
PLATINUM
. . 71
CERIUM ... . .
89
LITHIUM
. 72
DIDYMIUM ....
90
OXYGEN .
. . 73
ERBIUM
91
HYDROGEN .
. 73
NIOBIUM, or COLUMBIUM
91
NITROGEN
. . 74
THORIUM
' 92
FLUORINE
. 75
THALLIUM ....
92
CHLORINE
. . 75
MOLYBDENUM , . . .
92
BROMINE
. 76
RHODIUM ....
93
IODINE
. . 77
IRIDIUM
93
SULPHUR . .
. 77
OSMIUM
93
PHOSPHORUS .
. . 78
SELENIUM . . . .
93
ARSENIC
. 80
TELLURIUM ....
94
CARBON
82
94
PAET III.
ASSAY OF SILVER
. 97
ASSAY OF IRON . . .
159
GOLD
. . 125
NICKEL
163
MERCURY
. 135
COBALT . . .
164
COPPER .
. . 145
NICKEL AND CO-
LEAD .
. 150
BALT
165
BISMUTH .
. . 153
COAL . . .
171
TIN
. 156
CONTENTS.
XI
PAET IV.
PAGE
TABLE OF THE ENGLISH
MINT VALUE OF GOLD
ACCORDING TO ITS FINE-
NESS 179
VALUE OF GOLD COINS IN
THE UNITED STATES OF
AMERICA . .191
PAGK
EXPLANATION OF AMERICAN
GOLD TABLE . . . 192
TABLE OF THE AMERICAN
MINT VALUE OF GOLD
ACCORDING TO ITS FINE-
NESS . .195
INDEX
INTEODUGTION
INTRODUCTION.
XV
IN searching for and determining the different elements
mentioned in the following tables, the method adopted is
a direct examination for each separate element. The
beginner will find, by following the methods here de-
scribed, that his task will be simplified, and when practice
has made him proficient he can then look for several
elements out of one sample.
Table of ' Metallic ' Elements of Commercial Value.
Names of the Elements
Symbols
Atomic
Weight
Names of the Elements
Symbols
Atomic
Weight
Potassium .
K
39-1
Chromium
Cr
26-7
Sodium
Na
23
Iron .
Fe
28
Csesium
Cs
133
Cobalt
Co
29-5
Rubidium .
Rb
85-4
Nickel
Ni
29-5
Barium
Ba
68-5
Zinc .
Zn
32-6
Strontium .
Sr
43-8
Cadmium
Cd
56
Calcium
Ca
20
Copper
Cu
31-7
Magnesium
Mg
12
Lead
Pb
103-5
Aluminium
Al
13-5
Indium
In
Manganese
Mn
27'5
Bismuth
Bi
210
Tin .
Sn
59
Titanium
Ti
25
Antimony .
Sb
122
Mercury
Hg
100
Silver
Ag
108
Platinum
Pt
987
Gold.
Au
197
Lithium
Li
7
Table of ' Non-Metallic ' Elements of Commercial Value.
Names of the Elements
Symbols
Atomic
Weight
Names of the Elements
Symbols
1 Atomic
Weight
Oxygen
8
Sulphur .
s
16
Hydrogen
H
1
Phosphorus
p
31
Nitrogen
N
14
Arsenic
As
75
Fluorine
Fl
19
Carbon
C
6
Chlorine
Cl
35-5
Boron
B
11
Bromine
Br
80
Silicium .
Si
14
Iodine
I
127
XVI
INTRODUCTION.
Table of ' Metallic ' Elements of No Commercial Value.
Names of the Elements
Symbols
Atomic
Weight
Names of the Elements
Symbols
Atomic
Weight
Glucinum .
Be
4-7
Cerium
Ce
46
Lanthanum
La
46
Didymium
Di
48
Yttrium
Y
Erbium
Er
Terbium .
Tr
Niobium .
Nb
Tantalum .
Ta
37-6
Thorium .
Th
59-5
Uranium .
U
60
Thallium .
Tl
203
Tungsten .
W
92
Molybdenum
Mo
48
Vanadium
V
68-6
Rhodium .
Rh
52-2
Palladium ,
Pd
53-3
Iridium
Ir
99
Ruthenium
Ru
52-2
Osmium .
Os
99-6
Table of ' Non-Metallic ' Elements of No Commercial Value.
Names of the Elements
Symbols
Atomic
Weight
Names of the Elements
Symbols
Atomic
Weight
Selenium .
Tellurium .
Se
Te
39-7
645
Zirconium .
Zi
44-8
EXPLANATION OF THE TEEMS USED IN THE
TABLE OF THE ELEMENTS.
Element. One of the ultimate indecomposable constituents of any
kind of matter, as oxygen and hydrogen, which are the elements
of water.
Atomic Weight is the weight of the atom of an element as com-
pounded with that of the atom of another element, ascertained
from the proportions by weight in which they combine ; or,
leaving out of view the hypothetical idea of an atom, it is the
number expressing the proportions by weight in which the
elements combine, one of the elements, either hydrogen or
oxygen, being assumed as the unit for comparison with the
others. Oxygen and hydrogen combine to form water in the
ratio of 1 of hydrogen to 8 of oxygen ; and 1 and 8 are therefore
the combining proportions of hydrogen and oxygen also called,
to avoid hypothesis, their * combining equivalents. '
Symbol. An abbreviation of the name of one of the elements. Some
of the abbreviations are taken from the Latin meaning of one of
the words, such as silver, Ag, from argentum.
xviii INTRODUCTION.
The following- elements are nearly always found combined with
oxygen, and they are spoken of as oxides in the qualitative determi-
nation. For instance, in the case of Potassium (page 45) the expres-
sion, * The presence of potash is detected by the blowpipe in two
ways,' is used.
Potassium .... Potash.
Sodium ..... Soda.
Calcium Lime.
Magnesium .... Magnesia.
Aluminium .... Alumina.
Titanium ..... Titanic acid.
Lithium Lithia.
Phosphorus .... Phosphoric acid.
Silicium ..... Silicic acid.
Glucinum Glucina.
Tantalum ..... Tantalic acid.
Tungsten Tungstic acid.
Vanadium ..... Vanadic acid.
Niobium Niobic acid.
Thorium Thoria.
Molybdenum .... Molybdic acid.
Zirconium Zirconia.
The new earths announced as occurring in gadolinite and sa-
marsldte as mosandrin, philippin, decipin, scandin, holrnin, thulin,
samarin, ytterbin are not alluded to in this work, as the characters
of some of them are still a subject of enquiry. (See Delafontaine
Conipt Eend. 1880. x. c. 221).
PART I.
DESCRIPTION OF THE MOUTH BLOWPIPE
AND APPARATUS,
BLOWPIPE.
HOW TO USE THE BLOWPIPE.
BLOWPIPE FUEL.
LAMPS.
FLAMES.
SUPPORTS.
WEIGHING INSTRUMENTS.
TOOLS, SMALL IMPLEMENTS, AND APPARATUS.
REAGENTS, WET AND DRY.
TEST OR PROOF METALS.
BLOWPIPE.
THE mouth blowpipe is a small and convenient instrument
by which a blast of air may be forced through the flame
produced by the combustion of a candle or lamp fed with
oil or alcohol, so as to intensify the heat of the blast to
such an extent as to render it a substitute on a small scale
for the furnaces used in smelting ores as well as in
assaying.
It furnishes what may be termed a miniature blast
furnace, which is so perfectly under control that the tem-
perature can be made intense or mild at the will of the
operator; therefore the many advantages it affords the
mining explorer, the chemist, and metallurgist are great.
It is so portable that the little instrument with all the
necessary apparatus and reagents, both wet and dry, re-
quired for qualitative determinations as well as for assays,
can be packed up in a box twelve inches square. For
a rapid determination of ores and minerals it has no qual
and it possesses in careful hands most accurate means of
estimating the actual percentage of metals in most of the
commercial ores.
In the assay of gold and silver alloys the blowpipe
affords the operator very correct results, and also in the
examination of mineral coals it is invaluable. Makins
states that he has seen a skilful operator fuse a farthing
(a considerable weight of copper) by the blast afforded by
the lungs alone, and without fatigue.
B 2
BLOWPIPE AND APPARATUS.
PART I.
Blowpipes are made in many forms, but that devised
by Gahn and recommended by Berzelius may be con-
sidered to best fulfil all the requirements for general use.
It consists of a slightly taper-
ing tube, fitting into a cylindri-
cal chamber one inch long and
half an inch in diameter. The
chamber serves to collect any
moisture which may form in the
tube during blowing. Into the
side of this chamber a much
smaller tube in diameter, about
one inch in length, is inserted at
a right angle. The end of this
tube is covered with a platinum
tip (fig. 2) having a fine aper-
ture. Although silver and brass
tips answer very well it is always
best, when they can be procured,
to employ platinum tips, as they
are easily cleaned from soot, &c.,
by heating over the spirit lamp.
The assayer should be provided
wdth three or four tips, the finest
being used for qualitative work,
having an aperture of 0*4 milli-
metre in diameter.
Those required for reductions
should have a larger aperture.
The blowpipe should be provided
with a trumpet-shaped mouth-
piece, which is best made of horn or ivory turned in the
lathe.
The use of this mouthpiece very much diminishes the
PART I. BLOWPIPE. 5
fatigue of the muscles of the lips in long-continued blow-
ing, and the difficulty at first felt in preventing the escape
of air at the corners of the mouth is easily overcome by
practice. The mouthpiece is shown in the drawing (fig. 1).
The length of the blowpipe must be adjusted to the sight
of the operator, so that the test object may be held at such
a distance as to be distinctly visible.
HOW TO USE THE BLOWPIPE.
The blowpipe is held firmly in the right hand (see
fig. 3), and in such a manner as to facilitate a direction of
the flame upon the substance under pro- FIG. 3.
cess. The assay is held upon a support
by the left hand, care being taken to
retain the arms in their fixed position,
for unsteadiness will prevent an uninter-
rupted action of the blast on the assay.
The mouth furnishes the blast, which derives its force
from the muscles of the cheek. To prevent fatigue of the
respiratory organs, communication between the mouth
and chest must be closed during the blowing, and breath-
ing maintained through the nostrils. A few days' practice
removes all the difficulty at first experienced in producing
a continuous steady current, and it is by this means only
that proficiency can be acquired. The operation is com-
menced by filling the mouth with air, expanding the
cheeks, and then, keeping up a steady forcible pressure
with the muscles, respiration being allowed to go on as
usual through the nose.
The blowing is not unhealthy, and with a little perse-
verance is soon acquired, and assays made for several hours
in succession without fatiguing even the muscles of the
cheeks.
6 BLOWPIPE AND APPARATUS. PART I.
Beginners are apt to imagine that they must blow
with considerable force, and also if they stop blowing for
a moment, that the assay will be spoiled. In both these
cases a little practice convinces them of their error, and
they soon find that although the operator appears to be
trying to burst his cheeks in his efforts to fuse an assay,
he is quietly using his cheeks as a miniature air-bellows,
and not tiring himself in the least. A practised operator,
directly he lays down his blowpipe, even after a continuous
blow of fifteen minutes or more, will speak to a com-
panion with ease, without a single gasp, proving that the
blowing has not exhausted his breath.
BLOWPIPE FUEL.
Pure olive oil is the best fuel for reductions and quan-
titative fusions.
Alcohol makes a good fuel for qualitative work, and is
especially useful for the scorification and cupellation of
silver and gold alloys, as well as for heating glass tubes
and matrasses, and is employed in the assay for mercury.
By adding about one-seventh part of turpentine to alcohol
the reducing strength is increased.
Kefined rapeseed oil answers very well as a blowpipe
fuel. The ordinary illuminating gas makes a good fuel,
but it is much better for oxidation than for reduction.
The flame of a wax candle, or even the flame of an
ordinary candle, answers the purpose when nothing better
can be found. Although assays can be made from the
flame supplied by candles, yet such assays are generally
attended with considerable difficulty, owing to the small
volume of the flame.
Paraffin melted and poured into a lamp having an
open top and a broad wick attached to one end answers
PART I. BLOWPIPE FUEL AND LAMPS. 7
nearly all the purposes required for blowpipe fuel. The
great objection is that soot accumulates on the glass tubes
or porcelain vessels when heated over the flame.
In some countries the interior of South America, for
instance alcohol cannot be procured except at a great
cost ; but as crude spirits made from sugar-cane, &c., are
generally plentiful in such places, they afford the explorer
a good substitute for alcohol as well as oil, owing to the
presence of more carbon than pure alcohol contains. The
spirits, however, contain some water ; and after the fuel
is about one-half consumed it is best to empty the lamp
and fill again with fresh spirits.
BLOWPIPE LAMPS.
The form of blowpipe lamp generally used is the one
proposed by Berzelius and used by Plattner (see fig. 4).
The cistern is made either of sheet brass or tinned sheet
iron, about 4^ inches long, and slightly tapering from
1 inch in width to 1 inch at the end nearest the ope-
rator, and it is usually coated with a dark lacquer.
It is made to slide on a Grerman silver or brass rod, and
can be adjusted to the required height by a screw. At
one end of the lamp is an opening for introducing oil, and at
the other is the wick-holder. Roth of these openings are
closed by screw caps, with the thread cut on the inside.
The escape of oil is prevented by washers cemented to
the caps with shell-lac and wax. The wick-holder has
its greatest breadth at right angles to the axis of the lamp,
and must be cut off obliquely, to allow the flame to be
directed downwards. Cylindrical woven wicks, such as are
made for the Argand*burners, are best adapted for this
lamp, and they are pressed flat and folded lengthwise, so
as to be introduced fourfold.
8 BLOWPIPE AND APPARATUS. PART I.
The wicks must not fit too tightly, and should be
free from lime, which is sometimes used in the bleaching
of them.
On the blowpipe stand an arm is attached, which has
a metal ring on the top, about If inch in diameter.
FIG. 4.
The arm is movable, and, like the cistern, it can be moved
up and down, and it is kept in position by a small thumb
screw. The ring is covered with either a network of iron
or platinum wire, and is used for holding substances which
require to be heated.
PART I.
BLOWPIPE LAMPS.
The lamp just described is best adapted for burning
oils, but alcohol can be used .if required.
A small glass lamp for burning alcohol is used in the
mercury assay also for heating substances in the glass
matrasses, &c. (fig. 5). Flet- Jm. 6. FIG. 6.
, ' . x ' -, . (Half size.) (Half size.)
cher (of Warrmgton) has in-
vented a most useful blow-
pipe lamp, which possesses
the great advantage of being
clean and portable, and it can
be easily refilled by melting
solid paraffin and pouring it
into the reservoir. The lamp
is constructed of either tin
or German silver (fig. 6).
The paraffin reservoir is about
1 J inch in length, and 1 J inch in
width at its widest part, and tapers to \ inch at the wick
end, the depth being about 1 inch. The wick is about \ inch
in width and about -f^ of an inch thick, and is held in its
place by being run through a wick-holder at-
tached to the narrow end of the reservoir.
The reservoir is held by a flat-bottomed
hollow cup of a similar form, but made larger,
so that when the lamp has been used the
reservoir can be reversed and packed away
without injuring the wick (fig. 7).
The reservoir is made to slide up and
down on a strip of metal soldered to the Top View of
FIG.
cup, and by means of a thumb screw it can Lam ?' ze
be inclined to any angle necessary.
For all ordinary blowpipe work this lamp answers
every purpose, and it is one of the most convenient and
cleanly lamps that are in use at the present time. The
10
BLOWPIPE AND APPAKATUS.
PART I.
FIG. 8. (Half size.)
lamp required for using the ordinary illumination gas is
of the simplest description. Brush recommends the
following :
' A blowpipe gas lamp
may be readily made by
selecting an iron or brass
tube, 8 inches in length
and f of an inch in bore,
bending it at a right
angle at the middle, and
passing it through a
block properly cut, or
placing it in a mould,
which is then filled w r ith
melted lead. The top of
the tube is then flattened,
and the proper inclina-
tion given to the orifice
by filing ' (see fig. 8).
FLAMES OBTAINED BY MEANS OF THE
BLOWPIPE BLAST.
The assayer produces, when using the blowpipe, two
distinct flames. They are called the oxidising and re-
ducing flames. Practical knowledge of the way to create
and use these flames is essential, and until such know-
ledge has been acquired the operator cannot proceed in his
manipulations with safety.
The production of the flames can be acquired in one
hour's lesson, or from studying and carrying out the fol-
lowing instructions. Dr. Lamborn describes the blow-
pipe flames as follows :
' When we examine the flame of a common candle, we
discover that it is composed of four parts.
PART I.
BLOWPIPE FLAMES
11
(Half size.)
' At the base a small crescent (fig. 9) a 6, with a clear
blue colour ; higher up, and in the centre of the flame,
the dark conical portion c ; surrounding this is FIG. 9.
the luminous portion d\ and exterior to the
last is the scarcely perceptible mantle / e. The
student has to remark the nature of two of these
divisions : the exterior non-luminous part / e,
which is composed of gases already saturated with
oxygen, that under certain circumstances goes
over to bodies with which the flame is brought
in contact, and hence constitutes the oxidising
flame ; and secondly, the luminous portion d,
which consists of gases not yet saturated with
oxygen, and therefore capable of extracting that element
from easily reducible oxides, and hence called the reducing
flame.
' When the point of the blowpipe is held one-third of
FIG. 10. (Half size.) FIG. 11. (Half size.)
oi the wick
in the lamp /**
flame, as in ' - - '*
figure 10, a
flame is pro-
duced by
blowing that
is long, slender, and blue, which is hottest at the outer-
most point a, and is an oxidising flame. This action,
however, is strongest slightly beyond a, about cZ, in the
stream of heated gas.
' If now the point of the blowpipe be held as in fig. 11,
somewhat higher than before, and not quite within the
flame, a larger and more luminous cone of burning gases
may be driven in 'the direction b c ; within the bright
portion of the flame at a the above-mentioned chemical
12 BLOWPIPE AND APPARATUS. PART I.
action on oxides takes place, which causes this to be called
the reducing flame.''
The most important matter is to produce optionally
oxidation or reduction.
Oxidation is very easily performed, whilst reduction
requires more practice. Berzelius recommends the ope-
rator to take a small grain of tin, place it on charcoal, then
direct the blowpipe upon it ; it will soon fuse, and if the
operator has not produced a good reducing flame it will
become covered with a coat of oxide. The nature of the
flame must be altered until, by observation, the proper
kind is produced at will.
The longer the button of tin is kept bright the better
and more expert the operator.
BLOWPIPE SUPPORTS.
When a substance has to be examined by the blow-
pipe it must be held by some means firmly. The article
used is called a support. A suitable support should be
one that will not fuse at a high heat, combine chemically
with the fused body, or prevent its complete heating by
rapid conduction. The best supports are charcoal and
platinum wire or foil.
Charcoal makes an excellent support, as it is
infusible; it has great reducing power, and it is also
porous, allowing alkalies and fluxes to pass into it,
whilst metals and substances that are less fusible remain
behind.
Soft pine wood makes the best charcoal for blow-
pipe work. It should be well charred, and that which
snaps or smokes in the fire should be rejected. ' Hard
woods' generally contain a large percentage of ash, which
contains traces of iron and manganese, and in some quali-
PART!. BLOWPIPE SUPPORTS. 13
tative determinations the results are liable to be incorrect
by these metals being absorbed by the fluxes.
Straight pieces free from knots should be selected, and
sawed in the direction of the fibre into oblong supports,
about 6 inches in length and 2 inches broad.
For qualitative determinations small pieces of charcoal
answer every purpose ; and if the pieces used are too small
to be held by the hand, they can be supported on a strip
of tin or thin sheet iron and the assay proceeded with.
The saw for cutting the charcoal should be a ' cross-
cut ' saw with fine teeth, and a blade of 5 inches in
length, f of an inch in breadth, and -^ of an inch in
thickness. Cavities, deep or shallow, according to the
substance to be examined, are made by a borer, or by the
point of a knife in the charcoal, and the assay placed in
the same for treatment.
Oxidation, reduction, and fusion are sometimes so
rapidly performed on charcoal that the operator is not
certain of the result obtained. In such cases platinum in
the form of foil or wire is used.
Platinum foil is best used in a narrow strip about
3 inches long and 1 inch broad, and it is useful for oxida-
tion.
The substance which is to be oxidised is placed on it,
near one end, and heat is applied by the blowpipe flame
upon its under side. The conducting power of platinum
is so inconsiderable that the other end may be held
between the fingers without inconvenience.
For reduction platinum cannot be generally used, as
it forms fusible alloys with some of the metals ; nor
should sulphides, arsenides, or chlorides be heated in
contact with it.
Platinum wire should be about 2 inches long, mode-
rately thin, and bent into a hook at one end, which serves
14 BLOWPIPE AND APPARATUS. PAUT 1.
as the assay support. The wire may be held in the hand,
either with or without a holder, but the latter is more
convenient. It is best made out of a piece of hard wood
or iron turned ; and, to prevent injury to the wires,
FIG. 12. (Half size.)
holders are used, in which the wire is inserted into the
middle of two slits crossing each other at right angles ;
the latter are then shut tight by a band which is thrust
over them and arranged to screw up and thus hold the
wire (see fig. 12). The large end of the holder unscrews,
and five or six of the wires can be kept in a small hole
bored in the handle. The form used resembles a crotchet-
holder in nearly every respect.
After the wires have been in use they can be cleaned
by warming the ends in a test tube with hydrochloric acid,
or by fusing a bead of soda upon it, and then dissolving
it in water.
To use platinum wire, either heat the hook for a
moment over the lamp and then dip it into the flux to be
used, or moisten it and dip in the flux. Melt the flux
over the lamp, and when a good transparent bead has
been obtained add the portion to be assayed to it whilst
it is still hot ; or if that is not practicable moisten the flux
bead slightly and let the assay adhere to it.
Fuse the assay over the lamp, and the appearance of
the bead in reference to opacity, colour, and other charac-
teristics can be distinctly seen from all sides, and in this
way are colorations of the bead by metallic oxides parti-
cularly to be distinguished. Some fluxes are so thin that
they fall through the loop or hook, but by turning the
assay a few times the flux will generally remain on the wire.
PART I.
BLOWPIPE SUPPOKTS.
15
Platinum wire cannot be used when reduction to the
metallic state is required.
All oxidation and reduction experiments in which
the results are to be known by the colour of the fluxes
should be effected upon platinum wire.
FIG. 13. (Half size.)
FIG. 14. (Half size.)
Platinum spoons are useful for heating substances
with bisulphate of potash and saltpetre. Two sizes are
convenient, made similar to figs. 13 and 14.
Crucibles and capsules of fire clay are made by
kneading into a thick paste some fine FIG. 15. (Half size.)
elutriated fire clay and moulding them
as follows :
The crucible mould is made of brass,
and consists of three parts a plug, a
box divided into two parts, and a stout
ring to keep the box together (figs. 15
and 16).
Knead with the fingers some of the
elutriated fire clay and make it into
small balls, each one a little larger than
is necessary to form the crucible re-
quired; oil the inside of the box and .
the end of the plug ; place the clay B
ball in the box, and after pressing the
plug on the clay give the plug a couple Box.
of sharp blows with a mallet.
The box in the meantime must rest on a piece of
16
BLOWPIPE AND APPAEATUS.
PART I.
(Half size.)
hard wood, or upon an anvil (upon which has been pre-
viously placed a piece of old cloth or flannel). The
plug is then removed, and after that the ring; the box is
then separated easily, and the crucible is ready to be
dried. They should be dried very slowly at first, and
then baked in an oven, muffle, or crucible.
Capsules, or roasting dishes, or cups, are made in a
hard-wood mould (boxwood being generally used) by
pressing the clay with a pestle of the same. The clay is
FIG. 17. prepared in a similar manner as it is for
moulding the crucibles (fig. 17).
Oil both the mould and the end of the
pestle, place over the mould a thin piece of
paper, take a small ball of the elutriated
clay, place it on the paper, and then press
and turn the pestle round until the capsule
is of an equal thickness.
Kemove the pestle, take the paper by
two ends, and lift the capsule out and place
it to dry, the paper soon falls off, then
bake as in the case of the crucibles.
Open glass tubes, closed tubes, and bulb
tubes, made of hard glass free from lead, are
used for the ignition of bodies and minerals which be-
come volatile at a high temperature and deposit a subli-
mate on the glass tube.
Open glass tubes are useful when a substance has to
FIG. 18. (Half size.)
be ignited in an excess of air. They are made from 4
to 6 inches in length, and from ^ to J of an inch in
PART I.
BLOWPIPE SUPPOETS.
17
/Half'
diameter (fig. 18), of hard glass, and are
easily bent to the required angle by
heating them over the spirit or oil
lamp.
Closed and bulb tubes (fig. 19) are
employed when substances require heat-
ing to the exclusion of air as much as
possible. The bulb tube is especially
serviceable when ores and rocks have to be
examined to see if they contain water.
WEIGHING INSTRUMENTS.
A fine, delicate, as well as portable assay balance is
required for blowpipe assays. Mr. L. Oertling -has con-
structed a balance under the author's directions which
fulfils all the requirements.
The balance is constructed to carry 30 grains in each
pan, and to turn distinctly with j^- ^ of a g rain -
"
size of the case is only eight inches square by two inches,
deep. To prepare the balance for use, the front cover,
which is attached to the case by hinges, is folded back
under the case, where it is held by two brass buckles,
one on each side of the case. A stand is thus formed.
After the two sockets which receive the adjusting screws
have been turned outwards, place in them the two screws
(which will be found in the drawers), also the third
screw, which fits in the back of the lid. By means of the
three screws, assisted by the two levels attached to the
stand inside, the balance can be placed in a horizontal
position. Now hang to the ends of the beam the two
stirrup pans, which will be found fixed against the back
of the case in notches, from which they can be removed
by turning on one side a small latch which moves on a pin.
c
-6C>0{
^0- 6>
18
BLOWPIPE AND APPARATUS.
PART I.
The small milled head button at the top of the stand
may be removed, and the fork piece which holds the beam
firmly to the stand (without allowing the steel knife-edge
to come into contact with the agate planes) taken away.
The handle may now be put in its place, and the balance
is ready for use.
A glass sliding front is included in the balance, which
prevents dust and currents of air gaining admission ; also
FIG. 20.
If
two small drawers, in which are carried the adjusting
screws, the handle, the set of weights and riders ; also a
small pair of brass tweezers to handle the latter. The
weights are as follows :
10 grains I/O grain 010 grain
1 grain
0-5
0-3
0-2
o-i
0-05
0-03
0-02
0-01
PART I. WEIGHING INSTEUMENTS. 19
The riders are made of fine gold wire, and weigh 0-10
grain. They are used to increase the fine weighing
capacity of the balance by placing them on the top of
the beam (which is graduated) and sliding them from one
division to another.
At each end of the beam a small steel pointer is fixed,
at the back of which are ivory graduated scales. These
steel pointers help to indicate the weight of a substance
much finer than the weights can be conveniently made.
A pair of small metal pans and another pair made of horn
complete the balance.
The horn pans are used in weighing ores and minerals,
also in weighing the globules obtained in the mercury
The metal pans are used for weighing alloys and beads
of gold, silver, copper, &c.
For blowpipe assay purposes another balance is required,
which will weigh upwards of 30 ounces, and at the same
time must be sensitive and portable.
The author, after experimenting for several years, has
at last succeeded in constructing an instrument that
answers the purpose in all respects. This balance (fig. 21)
resembles in some of its features a steelyard.
A brass bar a, lOf inches in length, f of an inch
in depth, and T \ of an inch in thickness, represents the
beam. The beam is finely polished and graduated. On
the right-hand side the graduations represent pounds (Ibs.)
and ounces ; on the left-hand side the graduations repre-
sent fractions of ounces and grains.
On the right-hand side there is a large movable weight
6, which can be clamped at will by means of a small
set screw c at the top. On the left-hand side there is a
light weight d, which slides smoothly along the beam.
By sliding the large weight to ^, 1, H, and 2 Ibs. respect-
c 2
PART I. WEIGHING INSTRUMENTS. 21
ively, it shows the pounds as marked on the side of the
beam, whilst each mark represents 1 ounce.
The minor scale to the left represents 1 ounce in its
whole graduated length, whilst its subdivisions represent
each 10 grains, and by sliding the weight to one-half or
one- quarter of these divisions, 5 or 2J- grains may be
weighed by estimation. On the left-hand end of the beam
there is a weight attached (e) by means of a screw ; it
serves as a counterpoise, also as a stop to the light weight.
On the right-hand end of the beam there is also a stop (/)
to prevent the heavy weight sliding off.
The beam is provided with an indicating steel needle
g and with a fixed steel knife-edge, which works in rings
of hardened steel which are let into the brass part /t, called
the beam support. The part h has fixed to it a small
arc, graduated into ten divisions, by means of which the
balance can be made to weigh much closer by using the
sliding weights.
It has also a steel hook, which enables the assayer to
suspend the instrument by means of a string or wire when
he wishes to weigh any substance with great care.
The pan (fig. 22) is made of brass or copper, and it is
about 3 inches in diameter and 1 inch deep at the centre.
The pan is sustained by a steel hook (fig. 21, i), which is
connected with the short end of the beam.
At the upper end of the hook attachment two hard
steel rings are let in, upon which a knife-edge (which is
fixed to the beam) works. The hook is sharpened at the
point, so that the assayer can weigh small sample bags of
ore or minerals without using the pan.
The balance weighs 13^ ounces, and with the pan 14^
ounces ; it is very portable, and not liable to get out of
repair.
To show the capabilities of the balance, the author has
22 BLOWPIPE AND APPARATUS. PART I.
recorded the following experiments which he has made
with it :
Loaded with 32 ounces = 15,360 grains in the pan, it turns dis-
tinctly on the addition of 10 grains.
Loaded with 8 ounces = 3,840 grains in the pan, it turns distinctly
on the addition of 3 grains.
Loaded with 4 ounces = 1,920 grains in the pan, it turns distinctly
on the addition of 1 grain.
Loaded with ] ounce = 480 grains in the pan, it turns distinctly
on the addition of 0'5 grain.
Loaded with ounce = 240 grains in the pan, it turns distinctly
on the addition of 0'2 grain.
Loaded with ounce = 120 grains in the pan, it turns distinctly
on the addition of O'l grain.
When the large and small sliding weights both point
to zero the instrument is balanced. The readings are
always taken from the inner ends of the sliding weights. 1
TOOLS, SMALL IMPLEMENTS, AND APPARATUS.
One hammer for chipping and breaking rocks and
minerals, for making cupels, and for striking the pestle in
the steel mortar.
Total length of the hammer, about 10 inches; length
of hammer head, 2 J inches, having a face about f of an
FIG. 23. (One-quarter size.)
inch square at one end and coming to a sharp point at
the other. It must be made of hard steel (fig. 23).
1 This ba^nce is made only by L. Casella, 147 Holborn Bars, E.G.
PART I. TOOLS, SMALL IMPLEMENTS, AND APPARATUS. 23
A small hammer (fig. 24) is required for flattening
metallic buttons, and it should be made of highly tem-
pered Steel and brightly FIG. 24. (One-quarter size.)
polished.
A small steel anvil,
highly polished, about 1-J-
by 1^ inch and ^ inch
thick, is useful to flatten metallic beads upon, and to re-
move slags from buttons obtained in fusing assays.
To prevent the buttons flying off and being lost,
always wrap them up in a piece of paper before using the
hammer.
One of the most necessary implements used in pre-
paring ores and minerals for assay is a steel mortar.
The mortar consists of three separate pieces, each of
which is smoothly turned and made of hard steel (fig. 25).
A is the pestle, B is FIG. 25. (Half size.)
a cylinder in which
the pestle fits tightly,
and C is the mortar
into which both A and
B fit.
In using, place the
cylinder in the mortar,
then add the mineral
or rock, place the pestle in the cylinder, and with the
hammer strike a few hard blows. (It is best to place
the mortar on some firm base before using the ham-
mer.) The mineral will soon be reduced fine enough to
be removed to an agate mortar for its final grinding.
An agate mortar and pestle are used to grind to the
finest powder the ores for assay, also to crush up slags for
further examination (fig. 26).
A mortar about 2 inches in diameter in the clear on
24
BLOWPIPE AND APPARATUS.
PART I.
the top, and 2J inches on the outside, and -J of an
FIG. 26. inch in depth at the bot-
tom, answers the pur-
pose.
A small selection of
files is most useful. Flat,
round, triangular shapes
are best, and they should
not be more than 6
inches long.
A small knife and a pair of scissors are constantly
needed, and should be included with the other tools.
A steel magnet, 4 inches long, sharp at the end, like
a chisel, is used in the detection of iron, nickel, &c.
A horn spoon, made from a bullock's horn, cut, and
finely scraped in the inside, so that it is perfectly smooth,
is a most useful addenda to the assayer's outfit. The
horn is generally hardened by soaking it for some hours in
a weak solution of sulphate of iron or copper, after it has
been scraped. It is used for vanning or washing ores of
all kinds, also to wash slags after they have been powdered,
FIG. 27. (Quarter size.) to S66 if the Operation
has been carried on suc-
cessfully (see fig. 27).
Charcoal borers are
made of different sizes
and shapes.
Fig. 28 represents a borer used for boring holes large
FIG. 28. (Half size.)
enough to make the charcoal furnace, which holds
crucibles, mercury retorts, and roasting cups.
PART I. TOOLS, SMALL IMPLEMENTS, AND APPAEATUS. 25
Fig. 29 represents the borer mostly used in mak-
ing assays of silver and gold FlG - 29 (Half size.)
ores.
Fig. 30 is a long bore,
the small end of which is used for boring holes through
the coal cover and sides of the charcoal furnace. The
flat end is used for FIG. 30. (Half size.)
boring holes on char-
coal for qualitative de-
terminations.
Forceps with platinum tips are used to hold sub-
FIG. 31. (| nat. size.)
stances directly in the blowpipe flame when testing for
fusibility (fig. 31).
Brass forceps with very fine points are used to hold
small objects, such as the small silver beads obtained in
cupellation (fig. 32).
FIG. 32. (Half size.)
Iron forceps, very strong, are useful in rough work,
such as holding a button of metal whilst it is hammered on
the anvil, or raising and cleaning the lamp wick (fig. 33).
FIG. 33. (Half size.)
Cutting shears are used to clip pieces of assay silver,
gold, and all kinds of metals after they have been beaten
BLOWPIPE AND APPARATUS.
PART I.
or rolled out. They should be made of good steel, and
the blades kept sharp (fig. 34).
FIG. 34. (Half size.)
FIG. 35. (Half size.)
Steel pliers having fine points, with jaws slightly
roughed on the inside, are used to remove buttons and
beads from slags and
cupels, also in sepa-
rating a button from
slag by gently press-
ing the substance
after placing it near
the inner part of
the jaw, or to clean
a cupel bead the same way. Good pliers are often strained
by placing the substance to be pressed too near the
point of the pliers (fig. 35).
A magnifying glass composed of two convex lenses is
the best, and it answers all the purposes required in blow-
pipe work.
Two small mixing capsules, one of polished brass, the
other of horn, are used to mix the powdered mineral with
the flux, and then to pour the charge conveniently into
FIG. 36. (Full size.)
assay crucible, roasting cup, or paper cornet in the
assays (fig. 36).
the
PART I. TOOLS, SMALL IMPLEMENTS, AND APPARATUS. 27
A small ivory spoon is used to remove fluxes from the
bottles, and minerals from the mortar. After a little prac-
tice it is not necessary to weigh many of the fluxes, as,
the weight once ascertained, the operator can judge by
measure (fig. 37).
FIG. 37. (Full size.)
Two small wire sieves, one having 1,400 holes to the
square inch (wire sieving), the other 2,000 holes to the
square inch.
Punched screens will do, but it is difficult to get them
as fine as the sieving.
A stand is necessary to hold cupels and cupel moulds
for the cupellation of gold and silver.
Fig. 38 represents a useful form. The top is made
of iron, and is set in a wooden stand to F og
prevent the heat affecting the fingers during (Half size.)
the operation. (For cupels, see p. 29 ; for
moulds, see p. 29.)
A small cylinder of hard
wood, turned, is used to
prepare the soda paper
cornets for assays (fig. 39).
A small quantity of fine iron and platinum
wire is used for holding the small crucibles in
the furnace, and the pieces can be cut and bent
to suit (fig. 40).
The charcoal-holder and furnace is de-
scribed fully in the mercury assay.
Evaporating dishes and small cups, also watch-glasses,
are necessary when acids are used. It is best to have
FIG. 39. (Half size.)
28
BLOWPIPE AND APPARATUS.
PART I.
half a dozen different sizes.
FIG. 40. (Full size.)
FIG. 41. (Half
size.)
Figs. 41 and 42 are con-
venient sizes.
Test tubes for sepa-
rating gold from silver
are useful (fig. 43).
A few small pipe-
clay annealing cups to
collect the finely-pow-
dered gold that has
been separated in the
test tube from silver by means of acids are useful, as
FIG. 43. (Half size.)
c
D
the gold can be dried and annealed in them, and after-
wards removed for weighing in one lump.
Beaker glasses, a few small funnels, and a stand to
match are required (fig. 44).
FIG. 44. FIG. 45.
A small glass wash bottle is used for washing preci-
pitates, &c. (fig. 45).
PART I. TOOLS, SMALL IMPLEMENTS, AND APPAEATUS. 29
A small drop bottle to hold acids is useful (fig. 46).
A small cupel mould is used to FIG. 46.
make cupels for the assay of gold
and silver alloys, which are called
the 'previously prepared cupels' (fig.
47).
To make the above cupels, finely
crushed bone ashes that have been previously burnt, so
that they contain no animal matter, are moistened, and
the mould filled to the top, FIG. 47. (Half size.)
the mould resting on a solid
substance, such as a piece
of hard wood. The pestle is
placed on the top, and a
few sharp blows are struck
with a mallet or heavy piece
of wood.
The cupel is removed
and carefully dried. When
perfectly dry, it should be smooth at the top and show no
flaws or cracks.
A package of best Swedish filtering paper is re-
quired in some of the assays. Blotting or some soft
paper, soaked in a strong solution of carbonate of soda,
then dried and cut into slips about 1J inch long by 1
inch wide, is used in the assay of silver and gold ores,
and a supply should always be kept on hand.
The batea is one of the most useful parts of the
mining explorer and assayer's outfit, and it enables the
operator to make preliminary examinations of gold, silver,
copper, mercury, lead, tin, ores, &c. It is also used in
the assay of gold and tin ores.
Melville Attwood describes it as follows : * Batea is
the name given to the gold-washer's bowl or vanning
30
BLOWPIPE AND APPARATUS.
PART I.
dish, used in the placers and gold mines of Brazil a small
implement which affords the most simple method of
separating on a limited scale the grains of gold from the
dirt, sand, pyritic matter, magnetic iron, &c. The form
of the batea in common use in Brazil is a circular shallow
wooden dish or bowl, rudely fashioned with an adze and
chisel, varying considerably in depth and size, but never-
theless in practical hands giving remarkable results.'
The best form of batea is represented in fig. 48, and
John Eoach, of San Francisco, describes it as c a disk of
FIG. 48. (j_ size.)
17 inches diameter, being turned conical 12 degrees, will
have a depth of 1J inch from centre to surface. The
thickness may be J of an inch. The outer edge, perpen-
dicular to axis, will require wood 2^ inches thick for its
construction the best wood, Honduras mahogany.'
The author has used them for more than twenty years,
and finds that by taking a hot iron and blackening the
wood from the centre about H inch all round the pecu-
liarities of the separated gold, or material, are shown
more distinctly than with the batea in its normal condi-
tion as it comes from the lathe.
PART I. TOOLS, SMALL IMPLEMENTS, AND APPARATUS. 31
To use the batea requires practice, and to describe
the modus operandi is difficult.
Prof. Warington Smyth states as follows : c A quantity
of the material to be operated on having been mingled
and well stirred by hand with water in the bowl, it is
shaken from side to side and circularly with a variety of
movements suited to the form and the nature of the ore,
only to be acquired by long practice. The separation of
the gold is partly assisted by striking one side of the
bowl occasionally, so as to arrest the course of the particles
for the moment ; and, finally, several different layers or
lines of mineral matter may be distinguished from one
another, the gold occupying the lower position, then the
magnetic iron, then the pyrites, and lastly other wastes.'
Henry Hanks also gives a very good description of
the way to use a batea. He states
6 The manner of using the batea may be described as
follows :
4 A quantity of water will be required. This may be
contained in a tank or large tub, or at a convenient place
near the bank of a stream or lake.
6 The pulverised ore several pounds at a time is
placed in the batea, which is gradually sunk in the water.
Several times it is broken down with, the fingers, while
the batea floats on the water. When the ore is thoroughly
wet and formed into mud, the batea is taken by-the-bye
with both hands and again sunk in the water. A circular
motion is then imparted to it (soon learned by practice).
The lighter particles will continuously flow over the edge
and sink, while the heavier ones collect at the centre.
4 When only a small portion remains the batea may be
lifted, and the water held in the depression caused to
sweep round the centre, while one edge is slightly de-
pressed.
32 BLOWPIPE AND APPARATUS. PART I.
' This motion will gradually remove the heavier par-
ticles toward the depressed part. If there is any gold,
platinum, galena, cinnabar, or other unusually heavy sub-
stance, its gravity will resist the power of the water,
while comparatively light particles move slowly forward.
' The form of the vessel is such that the heaviest
matter forms a point, and can be closely observed. If
there is a particle of cinnabar present it will be found at
the point of the prospect, clearly distinct from all other
substances. The value of the batea to the prospector
cannot be too highly estimated, and it should come into
more general use.'
Bateas can be made over two feet in diameter, or only
a few inches. A portable and useful size is about 1 7 TO
18 inches in diameter.
By seeing the batea once used, and then taking time
to wash the first few samples, the operator very soon be-
comes an expert at the management of the batea ; and
when he has once learned its use he will seldom examine
strange ores without it.
REAGENTS REQUIRED FOR BLOWPIPE
ASSAYING.
All reagents which are employed in blowpipe investi-
gations should be chemically pure.
Dry.
1. Carbonate of soda.
2. Neutral oxalate of potassa.
3. Cyanide of potassium.
4. Borax (biborate of soda).
5. Salt of phosphorus, or microcosmic salt (phosphate
of soda and ammonia).
PART I. REAGENTS REQUIRED FOR BLOWPIPE ASSAYING. 33
6. Nitre (nitrate of potash or saltpetre).
7. Bisulphate of potassa.
8. Vitrified boracic acid.
9. Protosulphate of iron.
10. Arsenic (metallic).
11. Argol (bitartrate of potash).
12. Ked and blue litmus paper.
13. Common salt (chloride of sodium).
14. Fluor spar.
15. Quartz (silicic acid).
16. Graphite (soft lead- pencil scrapings answer every
purpose).
17. Sulphate of copper.
18. Magnesium wire (in testing for phosphorus).
19. Caustic potash.
20. Oxide of copper.
21. Oxychloride of lead.
22. Litharge (absolutely free from silver).
23. Finely crushed burnt-bone ash.
24. A small stick of roll sulphur.
25. Carbonate of ammonia.
26. Carbonate of potash.
27. Oxalate of nickel.
28. Chloride of ammonia.
Wet.
1. Nitric acid.
2. Nitrous acid.
3. Sulphuric acid.
4. Hydrochloric acid.
5. Ammonia.
6. Nitrate of cobalt.
7. Sulphide of ammonium.
The assayer can purchase all the above reagents from
i)
34 BLOWPIPE AND APPARATUS. PART I.
the chemist ; therefore it is not necessary to give any in-
structions in regard to their preparation.
To obtain pure metals for test or proof purposes to
prove the assays is frequently a difficult matter ; therefore
the author has added the methods adopted by himself to
obtain pur silver, gold, lead, copper, tin, bismuth, mer-
cury, and iron.
TEST OB PROOF METALS.
Silver.
. The silver used for both qualitative and quantitative
examinations by the blowpipe must be chemically pure to
enable the operator to make accurate and reliable assays
of either gold or silver.
For convenience it is best to have the silver in two
forms, one in the shape of an ingot say, about 1J
inch long and ^ inch square the other should be in thin
foil, which latter will be found most useful in the gold
assay.
If chemically pure silver cannot be procured from a
reliable source, such as a mint, a first-class laboratory,
or assay office, it can be prepared as follows : Dissolve
the purest silver that can be obtained in weak nitric acid,
dilute with water, allow the solution to settle for several
hours, after which decant carefully and reserve for use
only the portions that are perfectly clear, to which add a
solution of chloride of sodium (common salt) until the
white flocculent clouds of chloride of silver cease to appear.
The precipitation is then complete. Filter and wash the
precipitate repeatedly in warm distilled water, then dry
and fuse (in a new and perfectly clean crucible) with its
own weight of crystallised carbonate of soda and about
J of its weight of pure nitre. The heat should be
applied gently at first, and finally raised to the fusing
PART I, TEST OR PROOF METALS. 35
point of silver, and when cold the crucible should be
broken and the button of silver carefully washed. The
silver must be again dissolved in nitric acid, water added,
the solution allowed to settle, and great care taken in
decanting as before. The silver is precipitated as before,
and the precipitate repeatedly washed for twenty-four
hours with ivarm distilled water. Dry, and again fuse
with carbonate of soda. If this process is carefully carried
out the silver obtained will be found to be chemically
pure.
Gold.
Grold for blowpipe examinations should be pure, especi-
ally for assays of nickel and copper. The most convenient
form will be found to be that of a thin foil.
If not procurable it can be prepared as follows : Take
a piece of gold coin and fuse it with three times its weight
of silver, and when in the state of fusion pour into a
vessel containing cold water. Collect the granulations
thus formed, and dissolve in a flask or beaker glass with
dilute nitric acid. After boiling for fifteen or twenty
minutes decant carefully, and wash the gold residue with
distil' ed water; then attack the gold with strong nitric
acid (of 1-30 specific gravity) for twenty to thirty minutes.
Decant and wash repeatedly with warm water, then add
nitro-hydrochloric acid and boil until the gold is completely
dissolved. Dilute with water, warm slightly, allow the
solution to settle for about twenty-four hours, then decant
and add oxalic acid slightly in excess. The mixture of
trichloride and acid to be heated gently. The precipitation
is slow, but is greatly assisted by heat. When finished,
decant and wash on a filter ; afterwards heat over a gas or
lamp flame in an evaporating dish or capsule. The gold
is easily reduced by this means to a metallic state. Then
fuse with an addition of bisulphate of potash and cast into
D 2
36 BLOWPIPE AND APPARATUS. PART I.
an ingot or any other desirable shape. The gold can be
beaten or rolled into thin foil, and it is then ready for
use.
The author recommends the addition of bisulphate of
potash as an extra precaution in case that a slight trace of
silver should still remain with the gold before the fusion.
Lead.
Lead is difficult to procure entirely free from silver,
and has generally to be prepared by the operator.
It can easily be done by dissolving acetate of lead in
distilled water and then precipitating the lead by pieces
of metallic zinc, always rejecting the first portions of lead
thrown down. The second portion should be washed
repeatedly in warm distilled water, to remove any acid
still remaining, and afterwards dried carefully between
pieces of thick filter paper. The lead thus obtained
should be melted on charcoal (in a hole bored for the
purpose) by the blowpipe, and for convenience in use
some of it should be rolled or beaten out into thin foil
and the rest fused into the form of a small ingot. The
foil is used to wrap up the pieces of gold or silver alloys
preparatory to cupellation. The ingot shape will be
found most suitable for the following plan, which the
author has found very successful in the assays of silver
and gold ores: i.e. instead of using granulations, as
generally recommended, take the ingot, and by means of
a small fine flat file reduce the lead to the finest possible
powder.
By care and rejecting any large filings that may have
been formed, a 6 lead powder,' nearly as fine as ground
litharge, will be obtained, which can be intimately mixed
with the ore about to be assayed.
The lead filings so prepared can then be kept in a small
PART I. TEST OR PROOF METALS. 37
glass bottle, well corked, and will be ready for immediate
use.
The files must be kept in a small case by themselves,
and never used on any other metal but the pure lead, else
inaccurate results are likely to be obtained.
Copper.
The copper of commerce is seldom sufficiently pure
for proof purposes.
The following is the most convenient mode of prepar-
ing pure copper : Dissolve crystallised sulphate of copper
in distilled water, and precipitate the metal by a clean
ircn plate ; free the precipitated copper from the iron by
boiling with hydrochloric acid, dilute with water, allow to
settle, then decant and remove the precipitate to a filter,
wash repeatedly with warm water, then dry and fuse in a
clean crucible.
When cold, break the crucible, wash, then dry and
beat or roll into a thin sheet or foil.
N.B. Pure copper rolls easily, but it must be repeat-
edly annealed to obtain thin sheets.
Pure copper, especially when in the form of a thin
sheet, should be cut into narrow strips and kept free from
the atmosphere in a tightly corked bottle.
Tin.
The best qualities of commercial tin generally contain
3 per cent, of impurities. Pure tin can be prepared as
follows : Dissolve good commercial tin in hydrochloric
acid : thus hydrogen will be evolved and the metals all
converted into chlorides, with the exception of antimony
and arsenic. If either of these be present, it will combine
with hydrogen and be evolved as a gas, viz. as anti-
moniuretted or arsensiuretted hydrogen, and some of the
38 BLOWPIPE AND APPAKATUS. PAST I.
antimony may also remain as an insoluble black residue.
Any residue having been separated by nitration, the
liquid is to be evaporated to a small bulk and then treated
with nitric acid. This will convert the tin into insoluble
metastannic acid, a crystalline white body. The whole is
now evaporated to dryness, and then washed with a little
hydrochloric acid, after which it is to be thrown upon a
filter, thoroughly washed and dried, and subsequently
reduced by mixing it with charcoal, and heated strongly
in a crucible, when a button of pure tin will be the
result.
The button of tin can now be rolled or beaten out into
sheets or foil, and is ready for use.
Bismuth.
The chief impurities of commercial bismuth are
sulphur, traces of arsenic, lead, and iron.
The best method of purification is the following:
Dissolve the crude metal in nitric acid, and then concen-
trate the solution by evaporation. Next pour the clear
solution into a large bulk of distilled water. It will be
thus decomposed, and a white sparkling soluble powder
falls, which is a basic nitrate. This is to be removed and
digested for a time in a little caustic potash, whereby any
arsenious or arsenic acids present will be dissolved. Next
the basic nitrate is to be well washed, dried, and heated
with about one-tenth its weight of charcoal in an earthen
crucible ; thus the salt is reduced, and the bismuth sub-
sides in the pot in a state of purity.
The bismuth thus obtained can be broken into small
pieces and placed in a bottle for use.
Mercury.
The mercury of commerce is often adulterated with
lead, tin, zinc, bismuth, gold, &c.
PART I. TEST OR PROOF METALS. 39
Pure mercury can be obtained by the following
method : Take about half a pound of mercury, place it
in a bottle of one-quarter of its capacity, and add about
one ounce of powdered white sugar ; shake vigorously for
a few moments, then pour the portion of mercury that is
still in moderate-sized globules into another bottle, add
more finely powdered sugar, and again shake for several
minutes ; then filter the mercury by pouring it into a
small cone of blotting paper having its apex pierced with
a small pin. The filter retains the oxides of foreign
metals, also a portion of the mercury that is in a very fine
state of division. The mercury filters slowly ; but when
complete remove it to a small glass retort, distil at a
low temperature very slowly, and only (Mow about two-
thirds of the whole to go over in vapour. Collect the
condensed mercury and keep it for use in a bottle with
a glass stopper.
N.B. Mercury that has been used in amalgamation
works, even after having been distilled, invariably contains
traces of gold and silver, besides lead, &c. (often owing to
the rapid manner in which it is volatilised during the dis-
tillation of amalgams) ; and in selecting mercury for
purification it is always advisable to procure some that has
not been employed for such purposes.
Proof mercury should be tested for gold by dissolving
it in nitric acid, and if any insoluble residue remains the
mercury is impure and must be again distilled until found
to be pure.
Iron.
Chemically pure iron is very difficult to prepare. The
method used by Berzelius gives iron of sufficient purity
for blowpipe investigations, and is the one generally
adopted.
40 BLOWPIPE AND APPARATUS. PART I.
Clean ordinary iron filings are taken and mixed with
about one-fifth their weight of fine oxide of iron. The
mixture is placed into a refractory crucible and covered
with a layer of green bottle glass, such being used that is
free from oxide of lead. The whole is luted up, and
heated for an hour to whiteness. In this way traces of
carbon and silicon are oxidised by the oxygen of the iron
scale, and, such foreign matters being removed by the glass
flux, a button of pure iron subsides in the pot.
The button thus obtained, after being cleaned carefully,
ean be used as a proof, but it must be kept sealed up
from the air to prevent oxidation.
Piano wire of different sizes will be found not only of
sufficient purity, but also a most convenient form to use
in the assay of lead.
PART II.
QUALITATIVE DETERMINATION.
COLOUR OF SUBLIMATES ON CHARCOAL.
THE colour of the sublimates found on the surface of a
piece of charcoal after a mineral has been heated in either
the O.F. or R.F. frequently affords the assayer a very
good idea of the nature of the mineral to be assayed.
Charcoal ashes vary in colour, and care must be taken
not to confound the colour of the ash with that of the
sublimate. For instance, the ash which is formed on
some of the hard-wood charcoal by the blowpipe blast is
generally of a bluish white colour, whilst the ash obtained
from burning soft-wood or pine charcoal shows a dullish
or darkish white colour, and after cooling scarcely any
colour can be observed. The colour of the hard-wood ash,
however, remains unaltered when cold.
Before heating a mineral on charcoal apply a strong
R.F. to a piece of the charcoal about to be used. Note the
colour of the ash, and then heat the mineral on it. The
sublimate derived from the mineral is generally found
some distance from the charcoal ash, and it can then be
examined with comparative certainty.
The following table on the colours of sublimates on
charcoal, prepared by D. Forbes, will be found of use :
44
QUALITATIVE DETERMINATION.
PART II.
Colours of Sublimates or Coatings on Charcoal before
the Blowpipe in
Oxidising Flame. Reducing Flame.
White . . A
1
Greyish white.
Bluish white .
Reddish white
; Yellowish white
Faint yellow .
Yellow .
Sulphur yellow
Lemon yellow
Dark lemon yellow
Dark yellow .
Orange yellow
Dark orange yellow
^ Brown yellow .
[ Brown .
Reddish brown
(Red .
Dark red.
1 Copper red
Carmine red .
V Whitish red .
- Faint violet .
Te, As, Sb, Zn, Sn,
PbS, BiS, NaCl,
NH 4 C1, KC1, CdCl, J
PbCl, BiCl, NaBr,
KBr, Nal, KI, 11
LiCl, As
Sb, Bi, Pb, CuCl .
(Ag+Sb)
Sn .
Sn, Mo ...
Zn, PbOS0 3 .
Pb .
Bi .
Pb .
Te, CuCl, Cd, In .
Bi, Cd .
Pb, Bi .
CuCl
CuCl
Cd .
Te
Ag
Mo
(Sb + Ag+Pb)
(Ag+Sb)
Se ,
Pb, Sn, Zn, Mo 3 , Te,
As, Sb, NaS, PbS,
BiS, KC1, NaCl,
NH 4 C1, HgCl, SbCl,
ZnCl, CdCl, PbCl,
BiCl, SnCl, KBr,
NaBr, KI, Nal
LiS, LiCl, As
CuCl, Sb, Bi, Pb
Sn
Sn, Mo 3
Zn
Pb
Bi
Pb
Te, Cd, CuCl
Cd
Bi
CuCl
CuCl
Cd
Se
3 [ Blue
Mo 3
Iridescent
Sa* j Dark grey
t$ (Steel grey
. Cd . . . . Cd
. Se, As, CuCl . . Se, As, CuCl
. Se, As . . . Se, As
The following give no sublimate or incrustation in either flame.
BaO, SrO, MgO, A1 2 O 3 , Zr 2 3 , YO, ThO, EO, Si0 2 , Ce 2 O 3 , Cr 2 O 3 ,
Di, Fe, Au Ir, Co, Cu, Zn, Mn, Ni, Os, Pd, Co, Pt, Ru, Ta, Ti, Ur,
Vd, Wo.
PART II. COLOUK OF SUBLIMATES ON CHARCOAL. 45
The abbreviation of O.F. for the oxidising flame and
of R.F. for the reducing flame will in future be used.
POTASSIUM.
The presence of potash is detected by the blowpipe
in two ways.
1st. By the more or less intense violet colour imparted
to the outer flame when a substance containing it is
heated in the point of the blue flame.
2nd. By the property which potash has of producing a
blue glass when fused into a borax bead containing
protoxide of nickel.
In the first instance it is simply necessary to expose a
small quantity of the substance (held in the loop of a
platinum wire) to the point of the blue flame, when, upon
fusion, the outer flame immediately beyond the substance
should show the characteristic violet colour.
This reaction, however characteristic in the case of
tolerably pure potash salts, as the carbonate, nitrate,
sulphate, chloride, bromide, iodide, and cyanide, is very
easily interfered with.
Phosphates and borates of potash do not give it, and
even a small percentage of soda renders it invisible in
the overpowering yellow reaction.
When lithia is present it is .easily obscured by the
more intense red flame due to that alkali. In very few-
silicates is this reaction of value, as most of them contain
more or less soda ; and even when they are quite free from
soda the reaction is generally too indistinct, and particu-
larly so in the more infusible ones.
In employing the second method the loop of a platinum
wire is filled up with a fused globule of borax glass, to
which a small quantity of boracic acid has been added.
Sufficient protoxide of nickel (oxalate of nickel is the
QUALITATIVE DETEKMINATION". PART IT.
best salt to use) is now dissolved in it, so as to make the glass
bead, when cold, appear of a brownish colour. This globule
is now melted in the oxidising flame along with the sub-
stance supposed to contain potash, and when perfectly
cold is examined to see if it has changed its original
brown colour to a more or less blue tint. If no potash is
present, or too little of the substance has been dissolved
in the glass, the colour will be unchanged ; but if sufficient
of the substance has been employed, and it was not too
poor in potash, then the glass bead will be found to
possess a blue tint, not unlike that of a weak solution of
oxide of nickel in ammonia.
As the colour of the glass is unchanged when smaller
quantities of potash are present, this method is of little
use in the examination of most silicates, and the deter-
mination must be left to spectroscopic examination or to a
chemical analysis.
SODIUM.
When soda is fused in the point of the blue flame, the
outer flame is coloured strongly yellow, or rather reddish
yellow.
This property affords an excellent test for detecting
the presence of soda in its compounds, as it is only
necessary to heat a splinter (in the platinum forceps, or
in the loop of a perfectly clean platinum wire) in the
point of the blue flame, when, if soda is present, the outer
flame will be seen to enlarge itself and be coloured reddish
yellow.
This test is extremely sensitive. It is applicable to
silicates and the more infusible compounds, and it is not
interfered with by the presence of considerable quantities
of potash or lithia.
When potash is present in much greater quantity than
PART II. SODIUM, CESIUM, RUBIDIUM, AND BARIUM. 47
the soda, provided no phosphoric or boracic acid is
present, the outer flame nearest the assay is tinged more
or less violet, but farther off shows only the soda yellow.
If lithia is present the flame will be of a more or less
reddish yellow, or yellowish red colour, in proportion to the
greater or less amount of lithia contained in the substance
under examination.
CJESIUM.
Cassia is a rare alkali ; and although its volatile salts
communicate a violet colour to the flame, its determination
cannot be effected with certainty by the blowpipe, and it
must be examined by the spectroscope. The spectrum
of caesium characterises the element with certainty, its
pale blue lines being very brilliant as well as distinct.
RUBIDIUM.
Rubidia, like csesia, is a rare alkali, found generally in
mineral waters. It gives a violet colour to the flame, but
the definite determination must be referred to the spectro-
scope. Its splendid indigo blue lines, as shown by the
above instrument, are most prominent as well as charac-
teristic.
BARIUM.
Baryta and its compounds, when fused in the point of
the blue flame, communicate more or less an intense
yellowish green colour to the outer flame. When mois-
tened with a very weak solution of nitrate of cobalt and
fused in the O.F., it gives a light brown bead. With a
strong solution it gives a brown or brick red bead, which
loses its colour on cooling, and on exposure to air breaks
up to a faint grey-coloured powder.
48 QUALITATIVE DETERMINATION. PART II.
On charcoal alone the hydrate fuses, boils, swells up,
and is absorbed by the charcoal.
With soda on charcoal baryta fuses and is absorbed.
( )n charcoal alone the carbonate of baryta fuses easily to
a clear glass, which becomes enamel white on cooling, and
if longer heated become caustic, boils up, and is absorbed.
With borax on platinum wire baryta dissolves to a clear
glass, which, if sufficiently saturated, can be flamed to a
white enamel. If supersaturated the glass becomes of
itself enamel white on cooling. With salt of phosphorus
the reactions are the same as with borax. In silicates,
either natural or artificial, the blowpipe is altogether
inefficient to detect the presence of baryta without the
assistance of humid analysis.
STRONTIUM.
The compounds of strontium, when heated in the point
of the blue flame, colour the outer flame purple red. When
much baryta is present this coloration is obscured by the
yellow green due to baryta. When a soluble strontia
salt is dissolved in strong alcohol and the solution burnt
alone, or on a small piece of cotton wool attached to a
platinum wire, the purple red coloration of the flame is
seen. In some cases a few drops of hydrochloric acid are
previously added, which forms a chloride and colours the
flame more intensely. But if it is a sulphate of strontia
subject it to a K.F. on charcoal (forming a sulphide) ; then
treat it with acid and alcohol, which will give an intense
red flame.
The hydrate, when heated on charcoal, boils up in its
water of crystallisation, solidifies, and again fuses with
violence, and is absorbed by the charcoal. ' The carbonate
only fuses at its edges and effloresces at the same, and it
is reduced to strontia, giving a strong light and colouring
TART II. STRONTIUM AND CALCIUM. 49
the reducing flame red, and on cooling reacts alkaline for
test papers.
The red coloration of strontia is so much stronger
than that produced by lime, that a small quantity of
strontia can be detected in aragonite (carbon dioxide 44
and lime 56 = 100). The mineral must be previously
decrepitated, then heated in the blue flame (it does not
fuse). It will soon be observed that the flame is coloured
more red than it would be by an equally large piece of calc
spar.
When testing the carbonate or sulphate, the flame is
often noted to be first yellowish, but afterwards purple
red is seen.
CALCIUM.
Lime, when heated in the point of the blue flame,
communicates to the outer flame a weak red colour, much
fainter than that produced by strontia. In its compounds
this colour is more or less mixed with yellow. In the
case of carbonates it is at first yellow, and later on, as the
carbonic acid is driven off, it becomes red. The sulphate,
chloride, and fluoride all give this reaction.
The presence of barytes or soda in any quantity
obscures this test, which is also not visible in the com-
pounds of lime with phosphoric, arsenic, boracic, titanic,
and tungstic acids ; and amongst silicates (wollastonite,
silica 51*7, lime 48*3 = 100) stands alone in producing
a faint reddish flame before the blowpipe, due to the pre-
sence of lime.
Before the blowpipe lime is unchanged ; the carbonate
becomes caustic, and at the same time it appears strongly
illuminated by the flame, and, if in pieces, slacks and falls
to powder when moistened, and reacts alkaline. With
E
50 QUALITATIVE DETERMINATION. PART II.
borax it dissolves easily to a clear glass, which becomes
opaque on flaming. When the glass is saturated it
crystallises on cooling, and loses its round form, but in no
case does it become as white as the glass from baryta or
strontia.
With soda on charcoal it is not affected ; the soda, being
absorbed by the charcoal, leaves the lime behind.
With nitrate of cobalt it is infusible and acquires a
greyish colour.
When lime is associated with baryta or strontia, as
sometimes in heavy spar, strontianite, baryta, &c., the
powdered substance, when treated with soda on charcoal,
leaves the lime and oxides of iron on the charcoal surface,
whilst the other substances sink into the charcoal.
In silicates little dependence can be placed on re-
actions for lime, but in general the presence of lime may
be suspected by the following tests :
1st. The swelling or frothing up in testing for fusibi-
lity.
2nd. Keactions with borax and salt of phosphorus
prove that silicates containing lime dissolve easily,
and with salt of phosphorus alone the silica is
separated, and the glass on cooling is in most cases
opalescent.
3rd. With a small quantity of soda it fuses to a glo-
bule, but with more soda it gives a slaggy mass.
It is best, however, to employ the humid process.
MAGNESIUM.
Before the blowpipe magnesia does not give any sen-
sible colorations to the flame, and it remains unchanged.
The carbonate is decomposed by the heat and becomes
more luminous and reacts alkaline to test papers.
FALT II. MAGNESIUM. 51
With borax magnesia is easily soluble to a clear bead,
which can be flamed opaque, and after saturation gives
on cooling a crystalline glass, but less so than lime.
It is easily soluble in salt of phosphorus, forming a
clear glass, rendered opaque by flaming, and if fully satu-
rated the glass becomes milk white on cooling.
With soda on charcoal the soda sinks into the charcoal,
leaving the magnesia unchanged.
With nitrate of cobalt it acquires a flesh-red colour,
which is best seen when entirely cold. The phosphates of
magnesia melt and give a violet red colour on similar treat-
ment.
Native magnesia (periclase or magnesium oxide), the
hydrate (brucite, magnesia 69, water 31 = 100), the car-
bonate (magnesite, carbon dioxide 52*4, magnesia 47*6
= 100), and hydromagnesite (carbon dioxide 36*3, mag-
nesia 43*9, w T ater 19*8 = 100), and in Epsom salts
(epsomite, sulphur trioxide 32*5, magnesia 16'3, water
f51'2 = 100), the above reactions are sufficiently charac-
teristic to decide the presence of magnesia if the mine-
rals in question are free from other colouring metallic
oxides ; but in nearly all the other metallic compounds the
wet way must be resorted to, except in cases where the
physical properties or chemical reactions of the other
constituent of the mineral in question .give a clue to its
identity.
Zehmen gives the following method for distinguishing
ordinary limestones from dolomite or magnesian limestone
(which is often a question of interest). A quantity of the
finest possible powder is placed in a small depression on pla-
tinum foil, or a platinum spoon, and heated several minutes
strongly to a thorough red heat. Ordinary limestone on
cooling sinters together slightly, and can be turned out of
the platinum without breaking up if handled carefully,
E 2
52 QUALITATIVE DETERMINATION. PART II.
and it often shows a tendency to adhere to the platinum,
and therefore it requires a little assistance to detach it.
Dolomite (calcium carbonate 54*35, magnesium car-
bonate 45*65 = 100), on the contrary, does not sinter after
heating, but falls to pieces, forming a still more porous
and light powder, and many dolomites even on heating
swell up from the fact that the gas frequently carries off
traces of the powder with the flame.
ALUMINIUM.
Alumina in both the oxidising and reducing flames
remains unchanged. With borax it dissolves slowly, form-
ing a clear glass, which is not rendered turbid on flaming,
nor does it become so on cooling. If a large quantity is
added to the glass in the state of the finest powder it is
rendered opaque, and on cooling the surface becomes
crystalline and is almost infusible. With phosphate salt
it is dissolved to a clear glass, which remains so. A very
large quantity renders the glass semitransparent.
With soda on charcoal it swells up a little and gives
an infusible product, whilst the excess of soda is absorbed
by the charcoal. With nitrate of cobalt and a high tem-
perature it gives a fine blue compound, the colour of which
is most intense when cold.
In minerals which contain no colouring metallic oxide
the blue furnished by the action of nitrate of cobalt gives
a very good test for alumina.
MANGANESE.
The oxides are infusible both in the O.F. and R.F.,
and they leave on the charcoal the red oxide, which has a
reddish brown colour.
PART II. MANGANESE. 53
With borax the oxide is dissolved in the O.F., forming
a glass which is of an amethyst violet colour when hot,
and when cold a reddish violet. If too much mineral
is treated the glass may appear quite black, as the above
colour is very intense, and even opaque, unless pressed
flat or drawn out by the forceps. In the E.F. this co-
loured glass becomes colourless, and if very dark it is best
reduced on charcoal by the addition of a little tin.
With phosphate glass in the O.F., if much manganese
is dissolved, the glass, when hot, is brownish violet, and
when cold it is reddish violet, but it never becomes
opaque. If the glass contains but little oxide and in
nearly colourless, the addition of a little nitre will bring
out the colour.
On charcoal with soda in E.F. the oxide is not reduced,
and remains behind whilst the soda is absorbed by the
charcoal. In O.F. on platinum wire or foil w T ith soda, when
too much oxide is not used, a transparent green mass is
formed (manganite of soda), which on cooling becomes
bluish green and opaque.
In substances which do not contain metals giving
coloured beads with borate and phosphate salts in O.F.
and K.F. manganese is very easily detected by its be-
haviour with the above reagents, the former of which
gives a much more intense colour. If other colour-
ing metals are present in small quantities they do not
have much influence on the amethyst colour seen in the
O.F. bead, but in the reduction bead show their colours
(for example, iron oxides) distinctly, as the manganese
colour has disappeared. If much iron oxide is present the
bead will appear in the O.F. blood red, and after the R.F.
action yellow.
In case the manganese present is so small that it does
not colour the phosphate beads, a small crystal of nitre is
54 QUALITATIVE DETERMINATION. PART II.
placed in a porcelain capsule, and the phosphate bead,
having been made to take up as much as possible of the
substance under examination in the O.F., is, whilst fused,
quickly brought into contact with the crystal of nitre,
which causes the glass to swell up, and it is seen at the
point of contact to tint the froth an amethyst or rose-
red colour the instant after cooling, an effect due to the
formation of manganite of potash at the point.
If a substance is mixed with other volatile oxides, but
contains above 0*1 per cent, of oxide of manganese, it
should be brought to the finest powder and mixed with
two or three times its bulk of soda, then melted in O.F.
on platinum foil ; the soda forms manganate of soda,
having a transparent green colour, more so when hot, but
a bluish green on cooling. Even with less than 0*1 per
cent., by using two parts soda and one part nitre instead
of soda alone, the manganese is more completely oxidised
and tints the mass bluish green when cold.
If chrome was present the yellow chromate of soda
would give a yellow tint ; this, however, would not destroy
the tjst, which may even be used for finding a trace of
manganese in oxide of chromium ; the colour is, however,
when cold, yellowish green instead of bluish green.
To employ these tests with metallic alloys they must
first be oxidised by roasting, action of acids, or deflagration
with nitre. In case of sulphides and arseniates they must
first be roasted on charcoal.
If the ore contains at the same time both silica and
oxide of cobalt, this test would give a blue colour on treat-
ing it in this way, from the cobalt present; therefore
the test for manganese is destroyed and the mineral must
be determined by the humid way.
PART II. TIN AND ANTIMONY. 55
TIN.
Heat any compound supposed to contain tin with a flux
made of equal parts of borax and cyanide of potassium. A
malleable globule of tin will be obtained.
Sulphides of tin must be first roasted on charcoal,
then treated in E.F. with soda and borax. A metallic
button of tin will be obtained, which can always be
detected by removing the slag from it, and again placing
it on charcoal and applying the R.F. The globule cannot
be kept bright, and becomes covered with a crust of oxide,
which can only be removed with difficulty by adding borax.
For further particulars on tin, see Tin Assay.
ANTIMONY.
Antimony fuses easily on charcoal, and coats the char-
coal in R.F. or O.F. with oxide of antimony (nearer the
assay than the oxide of arsenic) in a thin layer of bluish
white, and it can be driven about the charcoal by a gentle
O.F. without colouring the flame, but if a R.F. be used
the flame will be coloured a faint greenish blue. As the
sublimate of antimony is less volatile than that of arsenic
it may be easily distinguished from the last.
When metallic antimony is fused* on charcoal and
heated to redness, and the blowing stopped, the fused metal
keeps itself a long time liquid and evolves a dense
white smoke, which deposits on the charcoal and at
last coats the globule itself with white pearly crystals
of oxide of antimony. This phenomenon is due to the
absorption of oxygen by the metal and the heat eliminated
in the combination.
Antimony with lead and bismuth may be detected by
dissolving the above metals in boracic acid, provided the
56 QUALITATIVE DETERMINATION. PART II.
fused mass is kept covered with the blue flame. A
coating of fine oxide of antimony is formed, if the heat
is not applied too strong.
Antimony and zinc both give a white sublimate on
charcoal near the assay. The zinc oxide is not volatilised
in the outer flame, whilst the oxide of antimony can be
driven from place to place or almost entirely volatilised.
If antimony is combined with tin or copper, the assay is
treated on charcoal in E.F. with soda and borax ; by this
means small metallic globules are formed. The globules
are separated by triturating and washing in the horn spoon.
The globules are then fused on charcoal in the R.F. with
3 to 5 times their volume of lead and a little boracic
acid. If the glass only is exposed to the E.F. the
antimony is volatilised, and it coats the coal distinctly
with its oxide.
In alloys of copper, silver, lead, and iron, a small piece
of the alloy should be dissolved in nitric acid, and the
antimony will be found in an insoluble white powder (anti-
monic acid), and it should be then dried and treated on
charcoal for the antimonial sublimate.
SILVER.
Silver can be detected with the greatest accuracy, and
the percentage estimated by following the instructions in
Silver Assay.
GOLD.
Gold can be detected with great certainty, and the
percentage estimated, by following the rules laid out in
the Gold Assay.
PART II. CHROMIUM AND IKOX. 5 7
CHROMIUM.
The oxides of chromium afford a distinct reaction
before the blowpipe when they are tested in the O.F. with
borax or salt of phosphorus, the beads appearing yellowish
green when quite cool ; and the bead (if free from the oxides
of lead or copper) in the R.F. becomes a beautiful eme-
rald green. If the above metals are present the beads
become when cool opaque, red, or grey.
IRON.
The sesquioxide of iron is unchanged by the O.F., but
in the R.F. it loses part of its oxygen, and then be-
comes black and is attracted by the magnet.
In O.F. it dissolves in borax, and if a small quantity
is present the glass is, whilst hot, yellow, and, when cold,
colourless. If in a larger amount it is, when hot, red,
and, when cold, yellow ; and if fully saturated is, when
hot, dark red, and, on cooling, dark yellow.
In R.F. the glass formed as above becomes bottle
green, and if treated on charcoal with a little metallic
tin it becomes first a bottle -green colour, and on continued
reducing copperas green.
With phosphate salt in O.F. the glass formed is, when
hot, yellowish 'red, and, in the course of cooling, it loses
colour, becoming yellow, then greenish, and lastly co-
lourless when cold. When saturated it is, when hot, dark
red, and, in cooling, successively brown red, dirty green,
and then brownish red when cold. The latter colours
show themselves much quicker during cooling than when,
borax is used.
In the R.F. the phosphate glass, if it does not contain
much iron, is unchanged, but if more saturated with iron
58 QUALITATIVE DETERMINATION. PART II.
it becomes, when red hot, and, in cooling, successively
yellow, greenish, and at last reddish when cold. Treated
with glass on charcoal, this glass becomes, on cooling, green,
and when cold colourless.
In detecting the presence of iron in its numerous
compounds the reactions of borax and salt of phosphorus
will in most cases be sufficiently characteristic.
In metallic alloys which are not easily fusible it is
only necessary to treat them with borax on charcoal in an
O.F. until the glass has taken up sufficient of the oxide
formed to give it a distinct colour. If the alloy is very
fusible, from containing lead, tin, bismuth, antimony, or
zinc, the R.F. should be used by directing it on the
glass, which causes it to absorb as little as possible of
these metals. In either case the glass is, whilst still fused,
separated by the forceps and treated on clean charcoal with
the R.F., which separates the readily reducible metals,
especially copper, nickel, arsenic, bismuth, antimony, and
zinc (which are to a great part volatilised and sublimed on
the charcoal around), and leaves the glass coloured bottle
green, due to iron. If the alloy contained tin the assay may
be of a copperas green colour ; if not it becomes so by treat-
ing with E.F. on charcoal with metallic tin (should, how-
ever cobalt have been present the glass will turn out blue).
The bead (free from any adherent reduced metallic matter)
should now be treated on platinum wire in a good O.F.
until all iron is fully oxidised (if the colour is too in-
tense for inspection a part of it only need to be taken
and fused with fresh borax, so as to dilute it), when, accord-
ing to the proportion of iron present, the colour will be more
or less yellow, or even brown red. If a little cobalt is
present the glass, while warm, is a dark green, and when
cold green forms the admixture of colours. When, on the
contrary, but little iron is present along with much cobalt
PART II, IRON. 59
it will appear, when hot, green, but on cooling pure
blue.
Compounds of iron with arsenic and sulphur may be
examined by several methods.
(a) In most cases it is best to fuse the substance
with borax on charcoal, using the K.F., and when the
whole is in fusion the flame should be directed on the
glass alone, so that the air may have access to the metallic
globules. As soon as the glass begins to be coloured by the
absorbed metallic oxide it is removed by the forceps, and
can be examined for iron in both flames and with tin.
(6) The sulphide or arsenide may be calcined on charcoal,
and a little of the oxide thus produced is taken up by a
borate globule upon platinum wire in O.F., until the glass
is coloured. Frequently when no metals having strong co^
louring properties are present this test suffices at once to
determine the presence or absence of iron. If not, the
glass can be treated on charcoal in E.F., which separates
copper, nickel, or any other easily reducible metals (some-
times to effect the separation of such metals a small
piece of gold or silver may be added to them, as it en-
ables the metals to separate much quicker by so alloying) ;
then the bead is left with the iron reactions visible and it
can be examined as before.
(c) According to Plattner the powdered substance can
be fused with borax and some lead on charcoal, covering
the whole with a good E.F. When the borax has united
and formed a pearl the flame is directed on to this alone,
so that air has access to the fluid metallic globule.
When the borate is coloured by the absorbed metallic
oxides it should be removed quickly with the forceps, and
treated on fresh charcoal in E.F. to reduce any oxide of
lead in the glass, after which it may be examined for iron
reactions as usual.
60 QUALITATIVE DETERMINATION. PART II.
In oxides, when no copper, nickel, chromium, or uranium
is present, the iron is recognised without difficulty. In
case of uranium a humid analysis is necessary, as this
metal gives the same coloration as iron.
With nickel the colour is more or less brownish yellow
or yellowish brown.
In case of both nickel and copper they may (as before
mentioned) be reduced out of the glass, when the colour of
iron is then distinctly seen. With cobalt the colour of the
glass has already been noted, but if very little iron is
present the wet way must be used. If manganese is
present the colour in O.F. will be violet red, or if very much
is present dark red when hot, and, on cooling, red with a
violet tinge. On treating such a glass in R.F. on charcoal
with tin the manganese colour disappears and the copperas
green is at once seen. If very little manganese is present
merely treat it in R.F., which will be sufficient to reduce
the manganese and bring forward the bottle-green colour
due to iron.
When a great deal of manganese is present the phos-
phate test shows the iron at once, as the manganese colour
of this glass is not very intense in the O.F., and in E.F. it
becomes colourless, whilst the iron colour after treatment
with K.F. remains generally reddish.
When iron is in combination with chromium the blow-
pipe test does not give a sufficiently decided result, owing
to the colours produced by the chromium.,
If, however, the substance be melted in the platinum
spoon with 3 parts nitre and 1 part soda, and the result
washed well with water, the residual oxide will at once
react for iron as usual.
If tungsten or titanium is present the O.F. will, with
borax or phosphorus salt, give the iron reaction, as the
above metals give too feeble a yellow colour to interfere with
PART II. IRON AND COBALT. 61
it, also with borax in R.F., but with phosphate in R.F. both
of these become darkened to brown red. The compounds
of iron with carbonic acid, sulphuric acid, phosphoric
acid, arsenic acid, tantalic acid, silicic acid, and alumina
are in general easily shown to contain iron by the reactions
with borate and phosphate salts. It is also the case with
most slags and other products of the arts.
In such metallurgical products as pig iron, steel,
brass, black copper, copper, tin, or lead (containing iron),
speiss, regulus, &c., the iron can easily be show r n by the
treatment given for alloys or compounds of sulphur and
arsenic.
COBALT.
Before the blowpipe in O.F. the oxide is unchanged.
In R.F. it does not fuse, shrinks a little, and is reduced to
a metallic powder, which receives lustre by friction and is
attracted by the magnet. In both O.F. and R.F. the oxide
is dissolved by borax, and gives, both when hot and cold, a
pure blue glass, which is seen, especially on cooling, to be
less intense than with borax glass, from equal saturation.
On platinum in O.F. with soda the oxide, if in very
small quantity, dissolves to a clear bright red mass, which
becomes grey on cooling. The examination for cobalt is
generally easy, and especially so when no other strongly
colouring metal is present. This being the case, the sub-
stance, when treated with borax in O.F., will indicate the
presence of cobalt by the blue colour of the glass. If iron
is present the glass, when warm, may appear green, from
the admixture of colours, but on cooling (if the iron be not
in very large amount) the blue is seen above the peculiar
colour arising from the mixture of bottle green and blue.
When the glass is treated in the R.F. it is not easily mis-
taken for any other reaction ; also the action of the R.F.
62 QUALITATIVE DETEBMINATICXN 7 . PART II.
renders a manganese glass colourless. This substance
if present, is no obstacle in the way of recognising the
blue of the cobalt, as it is when using the O.F. with iron
and cobalt.
Plattner detects cobalt in metallic alloys of nickel by
converting the metal into an arsenide before testing it for
cobalt by mixing it in thin scales or filings with a little
metallic arsenic, fusing them together in a small cavity on
charcoal with the R.F., and treating the fused button a
short time with borax directly with the tip of the blue
flame ; if any cobalt is present the glass becomes blue, and
if the amount is not too small the cleansed button will
impart a blue colour to a fresh portion of borax also.
NICKEL.
The protoxide in the O.F. is unchanged. In the R.F.
it is reduced to an infusible metallic powder, which is
magnetic.
With borax in the O.F. on platinum wire a little of the
oxide colours the hot glass violet, but when cold a pale
reddish brown ; with more oxide the colours are darker. In
R.F. with borax the glass becomes grey and cloudy or
quite opaque, owing to finely divided metallic nickel. On
continuing the blast the reduced metallic particles collect
together without fusing, and the glass becomes colourless.
With phosphate salt on platinum wire in O.F. it
dissolves to a reddish glass, yellow on cooling. In R.F. on
platinum wire it is unchanged. On charcoal with tin it
becomes at first opaque and grey, but after long blowing all
the nickel is reduced and the glass becomes colourless.
With soda it is insoluble in O.F., but in R.F. on char-
coal it is easily reduced to white metallic particles, which,
after washing, follow the magnet.
PART II. NICKEL AND ZINC. 63
Plattner detects a small quantity of nickel in oxides of
cobalt, manganese, and iron by dissolving a small quantity in
borax on platinum wire in O.F. the dark or opaque bead is
shaken off, and two or three such beads prepared. These
are treated in a cavity on coal,, or in a coal crucible, with
a small pure gold button in a strong, active K.F. until it
is certain that all the nickel is reduced from the bead and
collected in the gold button, which has been brought into
contact with every portion of the fluid glass by carefully
turning the coal. When the button has solidified, it is
lifted from the glass and freed from any adherent glass
between paper on the anvil. If the borax glass was not
supersaturated with oxides, so that none of the cobalt could
be reduced, the gold button treated for some time in the O.F.
on coal with phosphate will impart to this only the nickel
colour, reddish to brownish red whilst hot, and yellow to red-
dish yellow after cooling, according to the amount dissolved.
If, however, cobalt has been reduced it will oxidise sooner
than the nickel, and either produce a blue cobalt bead or
a bead which will be dark violet when hot and dirty green
on cooling, if some nickel had been oxidised.
In either case the button, freed from glass, is treated
with fresh phosphate in O.F. until the hot glass seems
coloured, when, if the original borax beads had not been too
highly supersaturated, the glass will show only the nickel
coloration ; if the metallic oxides were, however, free from
nickel the glass will be colourless (Plattner's 'Manual,'
p. 245).
ZINC.
If the substance contains much zinc, or when it is free
from other metals which form a sublimate on charcoal, the
presence of this metal is easily detected. When a small
amount of zinc is combined with much lead, bismuth, or
64 QUALITATIVE DETERMINATION. PART II.
antimony it is quite impossible to prove its presence with
certainty, and frequently the presence of tin prevents its
detection.
The examination for zinc is in all cases based upon the
reduction of the metal or the formation of sublimate
(white when cold and yellow when hot) on the charcoal.
This sublimate, being further tested by reheating with a
solution of nitrate of cobalt, produces the characteristic
yellowish green colour.
Large quantities of oxide of lead or bismuth in the
sublimate may obscure this reaction ; but in some cases
the lead and bismuth oxides may be driven farther off, so
as to leave the zinc reaction tolerably clear.
If the quantity of zinc present is extremely small,
and only produces a very faint coating of sublimate, which
might be easily lost mechanically, it is in such cases
better to moisten the charcoal first with a drop of nitrate of
cobalt before blowing. It must, however, be observed, if
much antimony or tin is present, a greenish colour is also
produced with nitrate of cobalt from combinations with
the oxide of cobalt which are not volatile in the O.F. (the
colour with tin a bluish green), and in such cases dependence
cannot be placed on this reaction.
When much zinc is present a zinc flame is observed
in K.F., and the charcoal is covered with a strong sublimate,
closer to the assay than that of lead oxide. Substances
containing zinc in combination with sulphur can be treated
alone on charcoal in K.F.
Those containing zinc as oxide with but little sulphur
are treated with soda on charcoal in the E.F.
Those containing other metallic oxides and earths
require borax in addition. A mixture of 2 parts soda with
1 to 1 1 borax glass on charcoal in E.F. (especially when
in combination with alumina) soon frees the zinc, and the
usual sublimate is readily formed.
PART II. CADMIUM. 65
CADMIUM.
Metallic cadmium fuses readily and volatilises, covering
the charcoal with a reddish brown (in thin films), dark
yellow, or orange-coloured sublimate of the oxide, which
still farther off on the charcoal gives an iridescent play of
colours.
The oxide treated on platinum is unchanged in O.F.
On charcoal in K.F. it is reduced, and covers the charcoal
with a red brown to dark yellow sublimate (colour best
seen when cold), as in the case of metallic cadmium.
In borax glass in O.F. the oxide readily dissolves,
and gives a transparent yellow glass when hot ; on cool-
ing it is almost colourless ; on larger saturation the glass
can be flamed to a milky enamel, and when still more
saturated it becomes enamel white on cooling.
On charcoal in K.F. che phosphatic glass is slowly and
but partially reduced, giving but a very faint sublimate
of a dark yellow colour ; the true colour is only seen well
on cooling. An addition of tin hastens the reduction.
With soda in O.F. the oxide remains unchanged, but
in K.F. it is reduced, with the production of the charac-
teristic sublimates before described.
It does not give any characteristic reaction with
nitrate of cobalt.
In searching for this mineral the means of detecting
the cadmium depends entirely upon the reduction and the
subsequent volatilisation of the metal, giving rise to the
characteristic sublimate of the metal.
Substances containing much cadmium give the above
reaction if powdered finely and heated quickly in the K.F.
If the mineral contains as little as 1 per cent, of cadmium
it is better to mix the powder with soda and heat for a very
short time in a K.F., when the sublimate will be seen.
F
66 QUALITATIVE DETERMINATION. PART II.
As zinc is frequently present with cadmium, the heat, if
continued too long, will also drive off the less volatile zinc,
the white sublimate of which may more or less obscure
the cadmium reaction.
COPPER.
The oxides of copper, when heated on charcoal in K.F.
with soda, yield a metallic button of copper.
When heated in the O.F. on platinum wire with borax,
they colour the glass strongly ; a little oxide causes a green
glass when hot and a blue when cold, and with more it is dark
green to opaque when hot, but greenish blue on cooling.
With borax in the K.F. on platinum wire, if saturated
to a certain degree, the glass soon becomes colourless, but
on cooling it becomes red and opaque. On charcoal the
copper is reduced to metal, and the cold glass is quite
colourless.
The sulphides of copper are roasted on charcoal with
the O.F. and E.F. alternately, and on the completion of
the roasting soda is added, a E.F. applied, and a globule
of metallic copper produced.
Silicates and other salts of copper dissolve in O.F. in
the glass fluxes to green beads, which should be blue on
cooling.
For full details of copper assay see p. 146.
LEAD.
Metallic lead fuses easily, tinging the flame light blue,
and in both K.F. and O.F. volatilises, covering the char-
coal around it with a sublimate of pure oxide of lead,
dark orange yellow when hot and sulphur yellow when
cold, on the outskirts of which is generally seen a thin
bluish-white sublimate of carbonate of lead. The flame
PART II. LEAD. 67
of the blowpipe chases these sublimates from place to
place on the charcoal, which, when red hot, reduces the
oxides, volatilising the metal to a greater distance when it
is redeposited as a sublimate of oxide, at the same time
colouring the flame light blue.
The protoxide of lead heated in O.F. on platinum alone
becomes darker in colour and fuses to a yellow glass. The
red oxide becomes almost black, and at a low red heat is
converted into protoxide, and it behaves as before stated
under similar circumstances.
On charcoal in both O.F. and E.F. all the oxides are
reduced to metallic lead with effervescence, which on con-
tinued blowing is volatile and is deposited as a sublimate
of oxide, which can be reduced again to metallic lead by
the K.F., which is thus tinged light blue.
With borax glass in O.F. the oxides dissolve readily,
forming a clear yellow glass, colourless on cooling. With
greater saturation this glass can be flamed opaque, and
upon full saturation on cooling it becomes of itself a
yellow opaque enamel.
In R.F. this borax globule upon charcoal spreads out
with effervescence, and the lead may be reduced to its
metallic state by continued blowing, leaving a clear borax
globule.
With phosphate salt in O.F. the oxide (the same as
with the borate) requires more saturation before the
globule shows any yellow colour when hot.
In R.F. the phosphate salt globule on charcoal becomes
greyish and opaque, and when the globule is saturated the
charcoal around is covered by a yellow sublimate of oxide.
The addition of tin to the globule makes it more opaque and
darker grey in colour, but it never becomes quite opaque.
With soda on platinum wire it dissolves in O.F. to a
clear glass, becoming yellowish and opaque on cooling.
o8 QUALITATIVE DETERMINATION. PART II.
With soda on charcoal it is reduced to metallic lead in
E.F., which on continued blowing covers the charcoal with
oxide.
INDIUM.
In O.F. the oxide becomes of a dark yellow colour,
does not fuse, and on cooling recovers its lighter colour.
On charcoal in E.F. it is slowly reduced and volatilised,
and the oxide sublimed on to the charcoal. During the
reduction the outer flame is coloured very distinctly violet.
With borax in O.F. it dissolves to a clear glass, feebly
yellowish whilst hot, but colourless on cooling. A more
saturated globule becomes opaque.
With borax in R.F. the glass does not change, but on
charcoal it commences to reduce and to give a sublimate
on the charcoal ; at the same time the violet colouring
of the outer flame is seen, and is not concealed by the soda
coloration.
With phosphate salt the reactions are the same as with
borate, but if tin be added to the glass in the R.F. the
glass on cooling becomes grey and opaque.
With soda in O.F. it is not dissolved, but on charcoal
in R.F. is reduced, and part of the metal volatilises and
forms a sublimate of oxide on the charcoal, whilst some
nearly silver white globules of indium are seen in the
soda.
BISMUTH.
Bismuth fuses very easily, and gives a coat of oxide,
which is dark orange yellow when hot, and lemon yellow
when cold, being yellowish white in thin layers.
The yellow coat is pure oxide, and the yellowish white
one (which is at the greatest distance) is carbonate with
PART II. BISMUTH AND TITANIUM. 69
some oxide of bismuth. It can be driven about on the
glowing coal like lead, but does not colour the R.F. during
the operation.
Bismuth combined with sulphur gives on charcoal a
white coat of sulphate of bismuth beyond the yellow coat,
but it is prevented by a small addition of soda.
When much lead or antimony is present, roast care-
fully on charcoal, then fuse with 3 times its volume
of bisulphate of potash in the platinum spoon, then treat
the mass with water in a small porcelain dish until every-
thing is detached from the spoon. Sulphate of potash
and other soluble sulphates are dissolved, leaving neutral
sulphate of lead and basic sulphate of bismuth. Antimony,
if present, remains behind as acid.
After decanting the clear solution the residue is boiled
in distilled water, to w T hich a few drops of sulphuric acid and
some nitric acid are added, when the sulphate of bismuth
dissolves, leaving a residue of sulphate of lead with any
oxide of antimony present. After nitration the bismuth
is thrown down from the warm nitrate by means of salt
of phosphorus as a white precipitate, which is collected
on a filter and tested with phosphate salt.
The phosphate bead on platinum wire is colourless, or
faintly yellow, but on coal with tin in E.F. becomes dark
grey on cooling, behaving there like oxide of bismuth.
Oxides of bismuth, if treated either alone or with soda
on charcoal, give the usual bismuth coating.
TITANIUM.
Titanic acid both in E.F. and O.F. on charcoal
assumes a yellow colour, but it is white again on cooling.
With borax on platinum wire in O.F. it dissolves
easily to a clear glass ; if much is present it appears
70 QUALITATIVE DETERMINATION. PART II.
yellow whilst hot and colourless on cooling, and becomes
opaque by flaming. In R.F. a small addition yields a
yellow glass ; more oxide yields a dark yellow to brown
glass. A saturated glass becomes emanel blue by flaming.
With phosphate salt on platinum wire in O.F. it dis-
solves easily to a clear glass, yellow while hot. In R.F.
the glass becomes yellow while hot, but reddens on cool-
ing and assumes a fine violet colour. If the acid contains
iron the glass becomes brownish yellow to brownish red on
cooling.
With soda in O.F. on charcoal it dissolves with effer-
vescence to a dark yellow glass, which crystallises on cool-
ing a,nd thereby evolves so much heat that the globule
glows strongly again. When perfectly cold the glass is
greyish white to white.
With cobalt solution in the O.F. it assumes a yellowish
green colour, similar to oxide of zinc, but not so fine.
Plattner recommends the following plan to detect
small amounts of titanium : In complex substances which
give no decisive reaction for titanium with the fluxes the
finely powdered substance is fused in a platinum spoon at
a moderate red heat with 6 to 8 times its weight of
bisulphate of potash, the mixture being melted in small
portions at a time. The mass is then dissolved in just
sufficient water in a porcelain dish over the lamp, and the
insoluble parts allowed to settle.
The solution, if concentrated, may be heated to boiling.
The clear solution is then poured into a larger dish, mixed
with a few drops of nitric acid diluted with at least 6
times as much water, and then boiled.
If the substance contains titanium the latter is dis-
solved by the fusion with bisulphate of potash and treat-
ment with water, and it is precipitated from the acid
solution by continued boiling as white titanic acid.
PART II. TITANIUM, MEECUEY, AND PLATINUM. 71
If the solution is not acidified with nitric acid before
boiling, a yellow ferruginous titanic acid is obtained when
the substance contains iron. The precipitated titanic acid
is collected upon a small filter, washed with water con-
taining nitric acid, and tested with phosphate salt either
on platinum wire or charcoal.
If the amount of titanic acid is so small that in R.F.
it does not impart to the phosphate salt the violet colour
of the sesquioxide of titanium, add a little sesquioxide
of iron when the assay is upon a wire, or a small piece of
iron wire when on charcoal, and fuse the glass a short
time with the R.F. ; it then appears yellowish while hot
and brownish red when cool (' Manual,' 1873, p. 323).
MERCURY.
The assay for mercury is treated fully on p. 135.
PLATINUM.
Platinum, when treated with borax or phosphate salt,
does not fuse, and is neither oxidised nor dissolved.
Platinum is found native, and forms alloys with
other metals iron, copper, rhodium, iridium, ruthenium,
osmium, gold, and silver. To examine an alloy for plati-
num dissolve a small piece in aqua regia (3 parts hydro-
chloric acid and 1 part nitric acid). If there is any black,
fine, metallic insoluble powder in the bottom of the flask
it is iridium. Separate it by decanting carefully, then
evaporate the blood-red solution almost to dryness ; the
acid fluid is then diluted with water ; a few drops of a
solution of potassa is added. A yellow precipitate is
formed, which consists chiefly of platinchloride of potas-
sium.
72 QUALITATiV^ DETERMINATION. PART II.
LITHIUM.
Lithia, when heated in the point of the blue flame,
communicates a fine purple-red colour to the outer flame.
According to Plattner, when lithia is fused upon platinum
foil it causes the platinum in contact with it to acquire a
yellow tarnish, which is removed by water, but upon drying
or heating leaves the platinum surface without lustre, as
if acted upon.
To detect lithia in its compounds it is only necessary
to heat them on a platinum wire or in the platinum forceps
and in the point of the blue flame. Observe the purple-red
colour communicated to the outer flame. This reaction
serves also for silicates. Those which contain very little
lithia require to be tested according to Turner's method, by
mixing I part of the impalpable powder with 2 parts fluor
spar and three parts bisulphate of potash, and by addition of
a little water rendering the mixture plastic enough to stick
to the loop of a platinum wire. This is now subjected to
the blue flame. If no lithia is present, only the violet
colour due to the potash employed will be seen, but if the
contrary is the case the lithia red will be seen even more
or less overpowering the violet. The presence of soda in
the mineral may render this reaction indistinct ; but if
boracic acid is contained in the substance the green colour
due to this body will be first seen, but it subsequently
gives place to the lithia reaction. In testing for lithia it
must be remembered that strontia and lime also produce
a red coloration of the flame. When soda is present along
with lithia the red coloration may be overpowered by the
intense soda yellow, especially if the heat employed be
high. By employing the outer flame and less heat the
lithia reaction is frequently seen when otherwise invisible.
Stein states that 1 part lithia in 2,580 parts soda gives
PART II. LITHIUM, OXYGEN, AND HYDROGEN. 73
a red coloration, if the substance be heated so as to soften
and render it porous by quenching it in tallow and then
heating it in the flame of a candle.
Potash interferes less with the lithia reaction, but
communicates a stronger or weaker violet tinge in propor-
tion to the amount present. When both potash and soda
are associated with an excess of lithia the outer flame will
be reddish violet nearest and reddish yellow farther away
from the assay. If soda is present in excess both potash
and lithia reactions disappear, but sometimes the lithia
can be observed by using less heat, as before men-
tioned.
If a lithia mineral containing phosphoric acid (but no
soda) be treated in the blue flame, two distinct colours are
seen in the outer flame, which do not mix with one an-
other, being the lithia red and a bluish green due to phos-
phoric acid.
OXY GEN.
According to Fuchs, this element is only detected in
substances which can readily be made to part with it in a
free state. In substances that give up their oxygen when
heated in a glass tube, the gas is recognised by its rekind-
ling a glowing match. This reaction is often inconclusive,
owing to the small size of the fragment under examination.
However, another test presents itself at once for these
small quantities. The assay is heated in a test tube with
a fragment of chloride of sodium and a few drops of
sulphuric acid. Chlorine is now evolved in place of oxygen,
and it may be recognised by its characteristic odour, or by
its bleaching effect on a piece of moist litmus paper.
HYDROGEN.
To detect hydrogen in water, place a small piece of
metallic zinc in a small porcelain cup, and add a few drops
74 QUALITATIVE DETERMINATION. PART II.
of sulphuric acid. Hydrogen gas is given off, which is
easily recognised by its sickly odour.
The examination for hydrogen does not come within
the scope of a blowpipe investigation, and it must be de-
termined by chemical analysis.
NITROGEN.
Substances containing nitrates detonate when heated
on charcoal. Heated in a tube with a little sulphuric
acid, they give off red fumes of nitric peroxide. A small
amount of a nitrate present in another salt or substance
can be readily detected by heating it with rather more
than its volume of bisulphate of potassa in a closed tube
or matrass. The tube becomes filled with gaseous nitrous
acid, the yellow colour of which may be seen by looking
down through the tube. Should there be so little nitrate
present that this colour cannot be plainly seen, the minutest
quantities may, according to Stein, be detected by heating
the assay with litharge, which at first absorbs the nitric
acid, but yields it up at a higher temperature. A slip of
paper which has been immersed in a solution of protosul-
phate of iron, free from sesquioxide and acidulated with
some sulphuric acid, is inserted into the neck of the tube,
and if nitrous acid is present it will assume a yellowish to
brown colour. In this way the nitric acid in a mixture of
1 part of nitre with 1,000 parts of sulphate of soda con-
taining only 0-0005 nitric acid can be distinctly shown.
The paper quickly loses its colour if too strongly heated,
and therefore the tube or matrass should be rather long.
Nitre, soda nitre, and nitrocalcite are immediately re-
cognised as nitrates by the above tests, and their bases
may be distinguished by the colour they impart to the
flame.
PART II. FLUORINE AND CHLORINE. 75
FLUORINE.
Fluorides, when treated in a closed tube, give off fumes
of hydrofluoric acid, which react acid with test papers and
sometimes etch the glass. If no acid reaction has taken
place, first heat with a little sulphuric acid in the closed tube,
and if that still does not evolve fumes of hydrofluoric acid
heat in a closed tube with a small quantity of bisulphate
of potash. In case no characteristic reaction has taken
place Berzelius recommends the following test :
The finely powdered substance is mixed with phos-
phate salt (previously fused on charcoal), and the mixture
heated in the open tube, so that the flame can be
carried inside the tube by the current of air. Under the
solvent action of the phosphate upon minerals free from
silica, hydrofluoric acid is formed, which passes through
the tube ; and it can be recognised both by its peculiar
pungent odour and by its effects on the glass, which it-
attacks and renders dull, especially where any moisture
has collected. The escaping air will also turn Brazil-wood
paper yellow.
CHLORINE.
According to Berzelius, ' chlorine may be detected in its
compounds by dissolving oxide of copper in salt of phos-
phorus or platinum wire in O.F. until the glass is opaque,
and then causing the substance under examination to
adhere to the soft bead, which is then treated with the tip
of the blue flame.'
4 If chlorine is present the bead will be surrounded with
an intense azure blue flame of chloride of copper, which
volatilises as long as chlorine remains. A fresh addition
of the substance will reproduce this reaction. Bromine is
the only other body occuring in minerals which produces
76 QUALITATIVE DETERMINATION. PART II.
a similar flame.' As the above frequently occur together
the result is not satisfactory without a still further in-
vestigation. When a substance gives the azure blue re-
action in salt of phosphorus, fuse another portion of the
compound in phosphate glass with copper oxide. As soon
as the fusion is complete stop blowing, let the glass cool,
then crush into the finest powder on the agate mortar
and attack it in a tube or matrass with a small quantity
of nitric acid. Add water, allow the assay to settle for a
few moments, then add a solution of nitrate of silver. If
chlorine alone is present the precipitate will be a milky
white. If the compound contains as much as J per cent, of
bromine the precipitate will have a beautiful light lemon
yellow tinge. If the compound contains a large per-
centage of chlorine to a very small percentage of bromine
the colour will only be observed at the moment of precipita-
tion ; but if a large amount of bromine is in the compound
the yellow colour is permanent, and will of ten be seen en-
tirely separate from the pure milky white precipitate
which is thrown down by chlorine. The colours, however,
cannot be correctly discerned after the test tube has been
shaken up. In mineral waters and aqueous salts the
slightest traces of chlorine can be detected (if very dilute,
evaporate down) by adding a few drops of nitrate of silver.
A milky cloud will be observed immediately after the
above addition if any chlorine is present.
BROMINE.
Bromides behave in a similar manner to chlorine, and
with phosphorus salt and oxide of copper the same reaction
takes place as with silver. The flame, however, has not a
pure azure blue colour, but inclines to green, especially at
the edges.
PART II. BROMINE, IODINE, AND SULPHUR. 77
When all the bromine has been eliminated the green
flame of the oxide of copper alone remains.
To distinguish bromides from chlorides Berzelius has
proposed to fuse them in a matrass with bisulphate of
potash, when bromine and sulphurous acid are liberated,
and the matrass is filled with reddish yellow vapours of
bromine, which can be recognised by their similarity to
that of chlorine notwithstanding the sulphurous acid.
Bromide of silver forms an exception, as it yields very
little bromine, but it may be distinguished from chloride
of silver by the asparagus green colour which it assumes
when exposed to the sunlight after fusion with the bi-
sulphate of potash.
IODINE.
Iodides, if fused with oxide of copper in a phosphate
bead, produce an intense green flame.
When iodides are fused in the matrass with bisul-
phate of potash, the iodine is sublimed and partly fills
the matrass with violet vapours, while sulphurous acid is
simultaneously evolved.
The test is so delicate that small quantities of iodine
may be detected in salts, &c.
SULPHUR.
Sulphur fuses in the matrass ; sublimes, leaving a fine
yellow sublimate when cool. If ignited on charcoal it
burns with a bluish flame, evolving sulphurous acid, which
is easily recognised by its characteristic pungent odour.
By roasting a finely powdered mineral in an open tube
sulphurous acid will be evolved, and if the odour is not
perceptible the presence of sulphur will be ascertained
by inserting a small strip of moistened litmus paper.
78 QUALITATIVE DETERMINATION. PART II.
According to Plattner, in some cases even a very little
sulphur may be detected by fusing the powdered substance
with 2 parts of soda and 1 part of borax on charcoal in E.F.,
provided no selenium is present. In the case of easily
fusible metals which contain only finely disseminated
sulphides and cannot be pulverised e.g. raw lead, black
copper, &c. a fragment of the size of the mustard seed or
small peppercorn is used. In case of metals that fuse
with difficulty, as raw iron, the amount may be obtained
by filing.
When the powdered substance is fused with soda and
borax in K.F. on charcoal, sulphide of sodium is formed,
which leaves a sulphur reaction when the fused mass
is removed from the charcoal, pulverised, and placed
on a bright sheet of silver (a silver coin will do), and
moistened with water. Sulphuretted hydrogen is evolved,
which colours the silver black with sulphide of silver if a
notable amount of sulphur is present, but if less is present
only dark brown or yellow.
A minute trace of sulphur can be detected in water
made acid (by a small addition of nitric acid) and then
adding a little nitrate of baryta in a test tube. If
sulphur is present a fine white precipitate of baryta is
thrown down. The precipitation is greatly facilitated by
slightly warming over the spirit lamp.
PHOSPHORUS.
Phosphoric acid imparts a green colour to the
flame, especially after having been moistened with sul-
phuric acid. This test is, however, not always conclu-
sive.
Crush up and then ignite the assay to expel any mois-
ture ; place in a tube with a little magnesium wire, close
PART II. PHOSPHORUS. 79
the tube entirely, heat strongly. Magnesium phosphide is
the result.
When the fused mass is treated with water and broken
up the characteristic odour of phosphoretted hydrogen is
evolved.
Pig iron may be examined for phosphorus by dissolving
a fragment in nitric acid ; then evaporating to dryness in
a porcelain dish, heat it strongly, and then test for
phosphoric acid as directed above.
Substances consisting of earths, metallic oxides, iron
ore, &c., are tested by intimately mixing (after they have
been ground to a fine powder) with 5 parts by volume of a
previously prepared mixture (4 parts by weight of soda
and 1 of silica) in the agate mortar, and transferring it to
a soda-paper cornet and fusing it in O.F. to a clear bead.
(In case of iron ores it is best to take 4 assays of about
0*5 grain each and afterwards treat as one globule.)
The bead is pulverised in the steel mortar, and the
powder boiled in a small porcelain dish with water.
Phosphate of soda, also the excess of soda, are dissolved.
The clear liquid is either filtered or carefully decanted
from the insoluble matter and removed into a small porce-
lain dish. If much silica has been dissolved and remains
in the clear liquid, add a little carbonate of ammonia,
boil, and the silica will be separated in a gelatinous form.
Filter, and to the filtrate add an excess of acetic acid,
then some acetate of lead, stir, and if the phosphoric acid
amounts to several per cent, a white precipitate of phos-
phate of lead is at once formed, which is collected on a
filter, dried, and fused in a shallow cavity on charcoal.
If the precipitate has been well washed a white or
yellowish globule with a crystalline surface is obtained.
When the precipitate formed by acetate of lead is so
trifling that it cannot be removed without partially de-
80 QUALITATIVE DETERMINATION. P A T II.
stroying the filter, a drop of dilute sulphuric acid must
be added, which produces a mixture of sulphate and phos-
phate of lead in such quantity that it may readily be
transferred from the filter to charcoal.
When this is fused by the blowpipe the sulphate is
reduced partly to sulphide of lead, which soon volatilises,
and partly to metallic lead, which gradually volatilises,
leaving small globules of phosphate of lead that can be
recognised with the aid of the magnifying glass by reason
of its characteristic qualities.
ARSENIC.
Arsenic on charcoal evolves an unmistakable smell of
garlic. A slight grey incrustation is formed some distance
from the assay, which in K.F. disappears, assuming a faint
blue tinge.
Metallic arsenides, if heated on charcoal with E.F.,
yield part of their arsenic, which volatilises, forming a
coat of arsenious acid. If a large amount of arsenic is
present greyish white fumes are evolved, and the odour of
garlic is recognised without stopping the blast. If the
latter is not recognised the glowing assay must be held
directly under the nose, so that the smallest quantity of
escaping arsenic may be recognised.
In cases of nickel and cobalt ores when arsenic is
separated with difficulty, fuse the compound with lead in
O.F. on charcoal, and the presence of the volatilising
arsenic will be ascertained by its odour.
Provided the quantity of arsenic is very small in a
metallic compound the following process must be resorted
to: brittle metals are pulverised to powder ; malleable
ones are reduced by filing :
Mix 1 grain with 6 volumes of nitre and ignite in the
PART II. AKSENIC. 81
platinum spoon with the blowpipe flame until no metallic
particles are visible. Arsenic acid is formed, which com-
bines with the potassa. The other metals are oxidised
and nitrous acid is liberated. The mass in the spoon is
now digested with water in a beaker glass over the spirit
lamp, until everything is removed from the spoon.
The clear solution is poured off from the oxides into a
small porcelain vessel, acidified with hydrochloric acid,
about 0*7 grain sulphate of magnesia dissolved in it by
heating slightly, an excess of ammonia added, and the
whole heated to boiling.
Arseniate of ammonia and magnesia separate and settle
quickly when the vessel is removed from the flame. The
clear fluid is decanted from the precipitate, which is washed
in strong water of ammonia, again allowed to settle,
and freed by decantation from the fluid, after which it is
dried in the vessel. The dry salt is mixed with 6 volumes
of a mixture of cyanide of potassium and soda in equal
parts, then treated (1) on charcoal or (2) in a matrass with a
narrow neck. In the former case it is fused in R.F., and
the volatilised arsenic detected by the odour. In the
latter case it is first warmed over the spirit lamp in the
matrass, to expel any traces of moisture (which are collected
by an inserted roll of blotting paper), after F 49
which the mixture is heated to fusion.
The arsenic acid is reduced, and forms
a sublimate of metallic arsenic in the neck
of the matrass a (fig. 49). If the amount
of the arsenic is too small to produce a
distinct mirror, cut off the neck above
the sublimate with a file, then hold the portion of the
matrass containing the sublimate in the flame. If the
sublimate consists of arsenic it will volatilise and yield
the arsenic odour.
G
82 QUALITATIVE DETERMINATION. PART II.
Oxide of antimony (antimonious acid), containing less
than -poVo part of arsenic when heated to redness in a nar-
row-necked matrass with 3 volumes of neutral oxalate of
potash and 1 volume of charcoal dust, will afford a very
distinct mirror, which on further treatment in the spirit
flame is volatilised with an unmistakable odour.
CARBON.
Pure carbon (diamond) in a fine state of division
glows like coal and burns slowly if placed on a piece of
platinum foil and the flame directed down on it. It is
consumed, the product of combustion being carbonic acid.
Coal, anthracite, graphite, asphaltum, amber, &c.,
and all such compounds of carbon volatilise when heated
in the platinum spoon, first with a mild O.F. and then
with a strong K.F., leaving nothing but silica, lime, and
other non-volatile elements. Minerals containing carbonic
acid are easily tested, and with great certainty, by crushing
them up finely and adding a little dilute nitric acid to
them in a glass vessel and observing whether any effer-
vescence ensues. The glass should be slightly heated if
no gas is evolved. If carbonic acid exists in a large
amount the effervescence is most violent.
In raw iron, steel, and brass, the carbon (no matter
how combined) is easily found by digesting a small frag-
ment in a porcelain dish with about 6 times its weight of
fused chloride of silver and some water acidulated with
a few drops of hydrochloric acid, leaving the whole covered
with a watch glass until all the iron is dissolved. The
iron is converted into protochloride, the carbon remains
behind, and a corresponding amount of silver is reduced.
As the carbon compounds may contain earthy matter,
they must be dried, mixed with 3 parts of antimoniate of
PART II. CARBON, BORON, AND SILICIUM. 83
potash, then heated to redness in a matrass over the spirit
lamp. The carbon is oxidised at the expense of the anti-
monic acid, forming carbonic acid, which combines with the
liberated potassa. When cold, fill the matrass nearly to
the neck with water, which is gradually heated to boiling.
The carbonate and sulphate of potash dissolve with part of
the undecomposed antimoniate of potash, whilst most of the
latter remains with the earths and metallic oxides.
To the warm solution a few drops of nitric acid are
added, which causes effervescence, more or less lively,
according to the amount of carbonic acid present. Not a
bubble ascends if the substance contains no carbonic acid,
but several will be seen when the most trifling amount is
present.
BORON
Is a substance found in nature combined with water,
soda, ammonia, and metallic oxides, and never native.
Turner has proposed a test for boracic acid in salts
and minerals as follows : The fine powder is mixed to a
paste with a little water and 1 part of a flux (it is better
to employ 3 parts to obtain a reliable test), consisting of
4^ parts bisulphate of potash and 1 part of finely powdered
fluor spar perfectly free from boracic acid. It is then fused
on a platinum wire within the blue flame, and as soon as
the water is expelled fluoboracis acid is found, which is
volatilised and imparts a yellowish green tinge to the flame.
This colour is very transient, however, and must be looked
for with great attention if little boracic acid is present.
SILICIUM.
Silicic acid, in the forms commonly known as quartz,
flint, &c., is infusible before the blowpipe. It dissolves
(when powdered finely) slowly in borax to a clear, diffi-
cultly fusible glass, which while hot is frequently co-
G 2
84 QUALITATIVE DETERMINATION. PART II.
loured by the metallic oxides present. It is scarcely at-
tacked by phosphate salt ; with soda it fuses to a clear
glass with effervescence.
Both naturaland artificial silicates can be tested by
fusing a bead of phosphate salt on a platinum wire, then
adding a splinter of the silicate and treating it in F.
The bases dissolve, leaving a silica skeleton, which floats in
the hot, clear bead.
Quartz rocks and all such directly infusible and
insoluble compounds of silica should be treated in the
following manner :
One part, very finely powdered, is fused with four times
its weight of carbonate of soda in the platinum spoon. When
fused, remove to a small beaker glass and add about 20 times
its volume of water, then add hydrochloric acid, enough to
make the solution a weak one. Warm the beaker over the
spirit lamp until the solution has been effected and the
carbonic acid gas expelled ; remove to a porcelain dish and
evaporate to dryness. When cold, moisten with hydro-
chloric acid, allow it to stand a short time, then dilute
with hot water, stir, allow to deposit, then decant the
fluid, and again treat the residue with warm water, after
which filter and dry. Kemove the fine white precipitate,
which is pure silicic acid.
The silicium in raw iron, steel, brass, &c., is easily se-
parated by dissolving a fragment in nitric acid, which holds
in solution the metallic oxides formed and leaves the silica
in a fine white powder, which should be tested by fusing
with soda on coal. If the powder contains silica, it will
be dissolved in the soda with effervescence.
GLUCINIUM.
Glucina alone is unchanged before the blowpipe. In
PART II. GLUCINIUM AND LANTHANUM. 85
borax it dissolves in considerable quantity, forming a clear
glass, which by flaming becomes milk white, as it does on
cooling when fully saturated. In phosphate salt it dis-
solves with the same reactions as borax. With soda on
charcoal it is unchanged. With nitrate of cobalt it shows
a faint bluish grey colour.
The blowpipe characters of glucina are not sufficiently
prominent to admit of its being recognised in such minerals
as contain it ; therefore it must be detected by the humid
analysis. To detect glucina the finely powdered mineral
must be dissolved in hydrochloric acid, then evaporated to
dryness, the residue moistened with hydrochloric acid, dis-
solved in boiling water, and the silica filtered out. The acid
solution is made slightly anmoniacal, when glucina and
any traces of sesquioxide of iron are thrown down. They
are collected on a filter, washed thoroughly, and heated
while moist with a solution of potassa, until the glucina is
redissolved and the iron remains behind. After diluting
the solution with water, filtering it, and making it slightly
acid with hydrochloric acid the glucina can be again thrown
down with ammonia, and may then be tested for alumina.
Filter, thoroughly wash, and shake in a test tube with an
excess of carbonate of ammonia solution, which dissolves
the glucina, leaving the alumina. On boiling the am-
moniacal solution the glucina goes down as a carbonate,
and this can be converted into pure glucina by ignition
in the platinum capsule.
LANTHANUM.
The oxide alone on charcoal is not changed.
With borax in O.F. it dissolves to a transparent colour-
less glass, which, if dissolved in a sufficient quantity, can be
flamed enamel white. If saturated, the glass of itself, on
cooling, becomes enamel white.
86 QUALITATIVE DETERMINATION. PART II.
In E.F. with borax it reacts the same as in O.F.
With phosphate it acts the same as with borax. With
soda on charcoal the soda is absorbed, and the oxide remains
with a greyish colour behind. As lanthanum is generally
found combined with cerium and didymium the exact
determination of it must be referred to the laboratory.
For humid assay see Cerium, p. 89.
YTTRIUM
Before the blowpipe is unchanged.
On borax it dissolves to a clear glass bead, which by
flaming becomes milk white as well as on cooling if fully
saturated.
With phosphate salt it presents the same reactions as
with borax.
With soda on charcoal it is unchanged.
Yttrium is but rarely met with, and then nearly always
in common with erbium in various combinations. The
wet way must be employed to correctly distinguish this
element.
TERBIUM.
The oxide is unchanged before the blowpipe. In borax
it dissolves to a transparent glass, rendered milk white on
naming or on cooling, when sufficiently saturated.
In phosphate glass it presents the same reactions as in
borax.
With soda on charcoal it does not change. It must be
determined by the wet way.
TANTALUM.
Tantalic acid in O.F. alone on charcoal becomes
PART II. TANTALUM, URANIUM, AND TUNGSTEN. 87
slightly yellow, but is white again when cold. In E.F. the
same.
With borax on platinum wire it dissolves easily to a
clear glass, which with a certain amount appears yellowish
while hot, colourless on cooling, and can be made opaque
by naming. With still more the glass becomes enamel
white on cooling. In E.F. the same as in O.F.
With phosphate salt in O.F. it dissolves largely to a
clear glass, which with a very large amount is yellowish
while hot, but colourless on cooling. In E.F. the above
glass undergoes no alteration.
With soda in O.F. with a little more than its volume of
soda it fuses on charcoal with effervescence and soon spreads
out, and with more soda it sinks into the coal. In the E.F. the
same reaction takes place and it cannot be reduced to metal.
The wet way must be employed for its compounds.
URANIUM.
The sesquioxide of uranium, when heated in O.F. with
phosphate salt, yields a yellow glass, which becomes yellow-
ish green on cooling and pure green in E.F.
This test is a very good one ; but when oxides of iron,
and probably titanic acid, are present the phosphate bead
becomes red on cooling, and the uranium colour can only
be perceived by treating the glass in O.F., when it assumes,
on cooling, a green colour mixed with much yellow.
Any further examination must be made by the wet
way.
TUNGSTEN.
Tungstite, according to Von Kobell, acts before the
blowpipe as follows :
On charcoal in E.F. it becomes black.
In phosphate salt in O.F. it dissolves to a colourless
88 QUALITATIVE DETERMINATION. PART II.
or yellowish glass, which in E.F. becomes fine blue when
cold.
Tungstic acid can be easily recognised by its examina-
tion with phosphate salt. The bead in E.F. becomes blue
when cold, or in the presence of iron more or less red.
The presence of tungstic acid in tin slags may be
recognised by the deep indigo blue solution which is
formed when the pulverised slag is warmed in a test tube
with hydrochloric acid.
VANADIUM.
Vanadic acid alone on charcoal fuses, is reduced, and
goes partly into the coal ; the remainder assumes the
colour and lustre of graphite and is protoxide of vanadium.
With borax on platinum wire in O.F. it dissolves to a
clear, colourless glass, but with more it gives a yellow glass,
yellowish green on cooling. In E.F. the above glass
changes, appearing brownish when hot and fine chrome
green on cooling.
With phosphate salt on platinum wire in O.F. it
dissolves to a clear glass ; if not in too small a quantity,
dark yellow while hot, and light yellow on cooling. In
E.F. the same as with borax.
Vanadium is a very rare metal, and has only been
found as an acid in a very few minerals. The further
examination must be made by means of a humid analysis.
PALLADIUM.
Protoxide of palladium is reduced at a red heat, but
the metallic particles are infusible.
In O.F. and E.F. on charcoal with borax the metallic
oxides are reduced without dissolving, and a metallic
button cannot be obtained.
PART II. PALLADIUM, RUTHENIUM, AND CERIUM. 89
With phosphate salt the same as with borax.
With soda on charcoal the soda sinks into the coal,
leaving the palladium as an infusible powder.
Palladium reduced from its oxides behaves, according
to Berzelius, as follows :
6 Carefully heated on platinum foil to low redness, it
acquires upon the surface a blue colour, which, however,
disappears at full redness.
4 On charcoal alone it is infusible and unchangeable.
With sulphur in K.F. it fuses, but in O.F. the sulphur
burns off, leaving the palladium behind. When fused
with bisulphate of potash in a sufficiently large matrass
it is dissolved with evolution of sulphurous acid. The
salt appears yellow when cool.'
RUTHENIUM.
This metal is only found in small quantities in native
platinum, and is grey white, brittle, and very infusible.
It is not attacked by fusing with bisulphate of potash,
and is scarcely acted upon by aqua regia. No characteristic
blowpipe reactions can be obtained from this metal.
CERIUM.
Before the blowpipe on charcoal the protoxide is
changed by O.F. into the sesquioxide, which remains
unchanged even in R.F.
In borax with O.F. it is soluble to a dark yellow or red
glass (similar to the sesquioxide of iron glass), but in cool-
ing it is yellow. If sufficiently saturated the glass can be
flamed opalescent, and if fully saturated it becomes so of
itself on cooling.
In R.F. the yellow glass becomes colourless, and a
90 QUALITATIVE DETERMINATION, PART II.
strongly saturated glass on cooling becomes enamel white
and crystalline.
In O.F. with phosphate glass it reacts the same as with
borax, but the colour disappears entirely on cooling. In E.F.
no saturation prevents the glass being transparent. It is
colourless both w^hilst hot and cold (which distinguishes
oxide of cerium from oxide of iron).
With soda on charcoal the soda is absorbed, and the
oxide is reduced to protoxide, which remains behind, of a
light grey colour.
As cerium, lanthanum, and didymium are generally
combined together, the following simple method is given
to enable the assay er to determine all three : The mixed
oxides, after having been ignited, are first treated with
weak, then with concentrated nitric acid, which extracts the
lanthanum and didymium. Upon evaporating this solution,
igniting the salt, and again treating the oxides with very
dilute nitric acid, any oxide of cerium which has been
dissolved now remains undissolved.
From the solution of lanthanum and didymium the
oxide^ are thrown down with ammonia and dissolved in
sulphuric acid. The dry salt being then dissolved to
saturation in water at 43 to 45 Fahr., and the solution
then warmed to 100, sulphate of lanthanum separates,
leaving the didymium salt in the solution, from which it
can be precipitated by potassa. The oxides may be
obtained still purer by repeating the process.
DIDYMIUM.
The oxide on charcoal in O.F. is unchanged, but in E.F.
with a strong heat it loses its brown colour and becomes
grey. In borax with O.F. it dissolves to a clear glass of
a dark amethyst colour.
PART II. DIDYMIUM, ERBIUM, AND NIOBIUM. 91
In phosphate salt it behaves the same as with borax.
With soda on charcoal it is insoluble ; the soda is
absorbed and the oxide remains of a grey colour.
For a minute examination see assay of cerium, p. 90.
ERBIUM.
The yellow oxide in R.F. becomes lighter in colour and
translucent in appearance.
In borax it dissolves with difficulty to a colourless glass,
which by naming, and also when saturated, is milk white.
With phosphate salt the same reactions as with borax.
With soda on charcoal it is unaltered.
The humid method must be employed for any further
examinations of erbium.
NIOBIUM, or COLUMBIUM.
Niobic acid, before the blowpipe on charcoal in O.F.,
becomes yellowish, but is white again on cooling. In
R.F. the same.
With borax in O.F. on platinum wire it dissolves
easily to a clear, colourless glass, becoming opaque by flam-
ing with a moderate addition, and with more becomes
opaque when cool. In R.F. yields a glass which, after
treatment in O.F., becomes opaque of itself, and on
cooling remains unaltered.
With phosphate salt on platinum wire in O.F. it dis-
solves largely to a clear glass, yellow while hot, but colour-
less on cooling.
In R.F. with a very large addition the glass becomes
brown. The addition of sulphate of iron causes a blood
red bead.
With soda in O.F. fuses with an equal volume of soda,
92 QUALITATIVE DETERMINATION. PAET II.
with effervescence, but with more soda goes into the coal.
In E.F. the same, and it cannot be reduced to metal.
The wet way must be employed for an accurate deter-
mination.
THORIUM.
Thoria alone before the blowpipe remains unaltered.
With borax on platinum wire it dissolves in small quantity
to a clear glass, milk white on cooling, if saturated, but if
it appears clear on cooling it cannot be made opaque by
flaming.
With phosphate salt, same as with borax. With soda
on charcoal it is insoluble.
Thorium is a rare element, seldom met with, and as
it gives no characteristic blowpipe reaction the humid
analysis must be employed.
THALLIUM.
Thallium melts very easily on charcoal, and when
touched with the point of the blue flame the metal is
surrounded by a green flame.
When being fused on charcoal a moderate amount of
white coat of oxide is formed at some distance from the
assay, which is driven off when E.F. is applied.
Its salts also give an intense green flame.
With the spectroscope it can be readily determined.
MOLYBDENUM.
When molybdic acid is heated on charcoal in O.F.
it volatilises ; at the same time the support acquires a
yellow coating, often crystalline, which becomes white
on cooling. In R.F. metallic molybdenum is formed,
which may be obtained as a grey powder by washing
PART II. MOLYBDENUM, ETC. 93
the pulverised charcoal. Sulphide of molybdenum, when
heated in O.F., yields sulphurous acid gas and a sub-
limate of molybdic acid.
In order to find a small amount of molybdenum in its
compounds it is necessary to have recourse to the wet way.
RHODIUM.
Rhodium gives no characteristic reactions with the
blowpipe.
IRIDIUM.
Iridium before the blowpipe cannot be determined.
It can be separated from platinum, gold, silver, copper, &c.,
by following the method laid out in the gold assay (Class
B, /), and the percentage estimated.
OSMIUM.
Osmium generally occurs with platinum and iridium,
&c., and forms, with iridium, iridosmine.
The metal as well as the protoxide and binoxide change
easily, when heated in the air, to osmic acid, which is
volatile and recognisable by its highly characteristic,
penetrating, and disagreeable odour, resembling that of
chlorine and bromine. If osmium be placed on a strip of
platinum and brought into the outer flame at half its
height, the flame becomes intensely luminous.
For minute portions the wet method must be employed.
SELENIUM.
Selenium, even when combined with other elements, is
easily determined by heating on charcoal, when it evolves
a strong odour of bad horse-radish. When heated in a
glass tube selenium forms a red sublimate.
94 QUALITATIVE DETERMINATION. PART II.
Selenium, when fused within the blue flame on coal,
volatilises with an intense azure blue flame.
The salts of selenium (selenates and selenites) are re-
duced in E.F. on coal, either alone or with addition of soda,
to selenides, which emit a distinct horse-radish odour.
TELLURIUM.
Tellurium is very rare, and is found alloyed with other
elements and as tellurous acid in tellurite. It is a
white, brittle, and easily fusible metal. It sublimes in a
glass tube over the lamp. Heated on charcoal, it burns
with a greenish blue flame, with production of dense white
vapours of tellurous acid.
ZIRCONIUM.
Zirconia is infusible and unchanged by either E.F. or
O.F.
If prepared from the sulphate and heated by a blow-
pipe it becomes so brilliant that it dazzles the eye, and
in this property it exceeds any other substance.
In borax it dissolves to a transparent glass, which
becomes on flaming, or if saturated on cooling, milk white.
In phosphate glass it dissolves slower than in borax,
and gives quickly an opaque glass.
With soda on charcoal it is unchanged.
With nitrate of cobalt in O.F. it receives a dirty violet
colour.
PAET III.
ASSAY OF SILVER.
GOLD.
MERCURY.
COPPER.
LEAD.
BISMUTH.
TIN.
IRON.
NICKEL.
COBALT.
NICKEL AND COBALT.
COAL.
SILVER.
ONLY a small proportion of the large amount of silver
which is at the present time produced for commercial
purposes is found native, and then not pure, as it is gene-
rally alloyed with a little copper, gold, platinum, mercury,
arsenic, iron, lead, bismuth, or antimony.
Native silver occurs in masses or in arborescent and
filiform shapes in veins traversing gneiss, schists, porphyry,
and other rocks ; it also occurs disseminated in native
copper and galena, but usually invisible to the naked eye,
therefore requiring the aid of a good microscope to deter-
mine its presence.
Silver, when pure, has a metallic lustre. Colour and
streak, silver white. Ductile. Hardness, 2-5- 3. Specific
gravity when pure, 1O5. Minerals containing silver are
found in veins of nearly all descriptions, and even in sea
water minute traces have been found by a careful ana-
lysis.
The principal minerals containing silver are as
follows :
Argentite : silver glance, containing 87 per cent,
silver, with sulphur.
Stephanite : brittle silver ore, containing 68 per cent,
silver, with sulphur and antimony.
Proustite: light red silver ore, containing 65'4 per
cent, silver, with sulphur and arsenic.
Pyrargyrite: dark red silver ore, containing 59 per
cent, silver, with sulphur and antimony.
H
98 ASSAY OF SILVER, GOLD, MERCUKY, ETC. PART III.
Argentiferous grey copper ore (fahlerz), containing
from 5-7 to 18-31*8 per cent, silver, with antimony
and sulphur.
Argentiferous sulphide of copper, containing 53 per
cent, silver, with sulphur and copper.
Polybasite, containing 72-94 per cent, silver, with
copper, sulphur, arsenic, and antimony.
Chilenite, containing 86*2 per cent, silver, with
bismuth 13*8 per cent.
Bromyrite, containing 57*4 per cent, silver, with bro-
mine 42*6 per cent.
Cerargyrite (horn or chloride), containing 7 5 '3 per
cent, silver, with chlorine 24-7 per cent.
Embolite, containing 60-72 per cent, silver, with
bromine and chlorine.
Sternbergite, containing 33*2 per cent, silver, with iron
36 per cent, and sulphur 30 per cent.
lodyrite, containing 46 per cent, silver, with iodine 54
per cent.
Selenic silver, containing 11*6 42*8 65*5 per cent.
silver, with selenium, copper, and lead.
Hessite, containing 62 '8 per cent, silver, with tellurium
37-2 per cent.
Silver is a metal extensively used in the arts and
manufactories, and many of their products contain it in
more or less proportions.
Silver will be found in the products as well as in the
refuse from nearly all lead and copper smelting works,
if carefully looked for, and a very small amount can be
determined with great accuracy. Any mineral, alloy, or
product containing what is termed 6 a trace of silver,'
about ^ ounce to the ton of 2,000 pounds, can be assayed,
and the metal extracted and determined with accuracy by
the following methods.
PART III. SILVER. 99
Assay of Silver.
In order to separate silver from its ores and compounds
by the blowpipe the previous metal must be formed into
an alloy with lead ; then the silver lead concentrated by
a process known as scorification, by which the bulk of the
lead, copper, &c., is oxidised ; then the concentrated silver
lead is subjected to the process of cupellation, whereby
all the lead and other base metals are oxidised and the
silver left in the form of a metallic button.
Commercial ores, especially very rich ones, frequently
differ in richness ; it is therefore advisable in all cases of
importance to make two or three assays of each sample,
and if the results do not agree to make one or two more,
and then to take the mean or average of the whole, and
to that add the loss of silver proved by the synthetical
assay. In assays of alloys, proof and synthetical assays
are absolutely necessary to prove the work.
Silver Assay.
The assay of silver is divided into three classes, A,
B, and C.
A. When the silver is principally in combination
with non-metallic bodies.
(a) Containing volatile matters, as sulphur and arsenic,
and so combined as to be decomposed by fusion
with borax and lead on charcoal.
(6) Containing sulphides not decomposed by borax and
lead alone (argentiferous sulphides of molyb-
denum).
(c) Containing chlorine, bromine, and iodine, with little
or no other volatile matters.
(d) Consisting of metallic oxides, easily reduced on
charcoal (litharge, &c.)
(e) General method adapted to the assay of a, 6, c ;
either to one or all.
u 2
100 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
B. Metallic alloys ready for cicpellation after the
necessary addition of lead,
(a) Bar and ingot silver, standard silver, coins, native
silver, alloys of silver, gold, and copper.
(7. Metallic alloys requiring either distillation, or
fusion with fluxes before they are ready for
cupellation.
(a) Containing mercury in the form of amalgam.
(6) Test and precipitated silver. Eetorted silver
amalgam.
(c) Containing copper or nickel with more or less sul-
phur, arsenic, zinc, black copper, brass, and
German silver.
(d) Containing tin argentiferous tin, bronze, bell
metal, gun metal, and bronze coinage.
(e) Containing antimony, tellurium, or zinc.
(/) Iron bears from smelting furnaces and silver-steel,
&c.
(g) Containing alloys of lead or bismuth with silver, in
which the proportions of the former predominate.
(h) Containing copper in the form of coins, ingot, sheet,
or wire ; cement and copper nickel alloys con-
taining silver.
A. (a) Consists of most commercial ores which con-
tain iron, copper, and arsenical pyrites, antimonial glance,
blende, selenides, silver glance, sulphide of silver, ruby
silver, sulphide of silver and copper, miargyrite, &c. ; also
copper ores, as copper glance, purple copper, fahlerz, &c.;
also lead ores, as galena, selenide of lead, &c. ; also copper
and lead mattes, lead sublimate, and cobalt speiss.
Reduction to Silver Lead.
The ore is reduced to powder and passed through a.
sieve of 2,000 holes to the linear inch; it is then tho-
PART 111. SILVEE. 101
roughly mixed and 1*5 grain weighed out. The ore is
fluxed with borax and lead. The amount of borax required
is dependent on the fusibility and amount of matter to be
slagged. Ores containing much gangue, iron, cobalt, or
tin require 1J grain borax glass. When ores contain
little gangue and much metallic sulphides 0*8 to 1*2 grain
borax glass is quite sufficient. Should the assay during
the fusion show itself refractory, a little more borax may
be added to it.
The amount of lead required depends on the other
metals present in the ore. A substance containing 7 per
cent, copper or 10 per cent, nickel requires five times its
weight of lead (7 -5 grains), but when it contains more
than this amount the proportion must be dependent on the
amount of copper, &c., present. When this is not known
it is in all cases better to use too much than too little lead,
as in the last case the separation of the silver from the
copper is not effected, and a lead alloy rich in nickel can-
not be cupelled.
The following table will show the relative proportions
to be employed :
Copper glance, containing about 80 per cent, copper, requires
15 times its weight of lead.
Covellite, containing about 65-66 per cent, copper, requires
12 times its weight of lead.
Purple copper, containing about 55-60 per cent, copper, requires
11 times its weight of lead.
Tennantite, containing about 48-50 per cent, copper, requires
10 times its weight of lead.
Kupferblende, containing about 41-40 per cent, copper, requires
10 times its weight of lead.
Fahlerz, containing about 30-40 per cent, copper, requires 10
times its weight of lead.
Cupreous bismuth ore, containing about 34-35 per cent, copper,
requires 10 times its weight of lead.
Copper pyrites, containing about 30-34 per cent, copper,
requires 10 times its weight of lead .
102 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
Sulphide of copper and silver, containing about 30-31 per cent.
copper, requires 10 times its weight of lead.
Tin pyrites, containing about 29-30 per cent, copper, requires
7 times its weight of lead.
Eukairite, containing about 23-25 per cent, copper, requires 7
times its weight of lead.
Bournonite, containing about 12-13 per cent, copper, requires
7 times its weight of lead.
Copper regulus, containing up to 45 per cent, copper, requires
10 times its weight of lead.
Copper regulus, containing up to 50-60 per cent, copper, re-
quires 10 times its weight of lead.
Lead speiss, containing up to 10-40 per cent, copper, requires
10 times its weight of lead.
Cobalt speiss, containing up to 40-50 per cent, copper, requires
10 times its weight of lead.
The assay having been prepared, is poured with care into
a soda-paper cornet, placed in a charcoal bore of about T 4 ^
FIG 50 (Full size ) of an inch in diameter at the bottom,
and from T % to -^ at the top. The
cavity is bored wider at the top, to
allow the flame to reach down to the
bottom of the bore. The top of the
cornet is then closed up with a pair
of pliers and pressed firmly down
(see fig. 50). The assay is now in-
clined towards the flame, and a re-
duction flame, at first moderately
strong, is employed to cover nearly
all the top of the assay. The paper,
is not consumed until the par-
ticles below it have entered into fusion and prevented
mechanical loss. The whole assay is now submitted
to a strong but pure R.F. at an angle of 30 to 35
degrees. By the action of this flame a part of the sulphur,
arsenic, antimony, zinc, &c., is volatilised, but the greater
PART III. SILVER. 103
part, along with the metallic bases, unite with the lead to a
globule, whilst the gangue, the difficultly reducible metals,
and a smaller part of the easily oxidisable but non-volatile
metals (which have, been oxidised by the first action of the
heat) combine with the borax to form the slag. With re-
fractory ores it often appears as if the slag were quite free
from lead globules; but this is not to be trusted to, as often,
under the surface of the well-fused slag, unacted-upon par-
ticles of the ore may be concealed, which is only to be
obviated by moving frequently the charcoal, so as to change
the portion of the assay ; this must be done also with easily
fusible assays, as by this means the lower part of the assay
and the carbonised soda paper is exposed to the flame.
As the paper is hardly acted upon in a good R.F., it is
necessary to direct the flame on to the slag, so as to
cover it but leave the paper on one side with access
to the air, by wilich it is consumed, while the slag is
not affected. When consumed, the whole slag is again
covered by the R.F., to reduce any litharge that may
have been formed, and which by this means is united to
the main globule.
If the slag, after being treated thus in the R.F. and
moved about several times, forms a globule itself, and
shows no lead globules, and is perfectly fluid, it may
be considered free from silver. Whilst the slag is
covered with the E.F. the metallic globule is only touched
by the side of the flame, to keep it perfectly fluid and
ready to take up any straggling lead globule (fig. 51).
The assay is allowed to cool, and then removed with the
pliers and placed between two thick pieces of paper on the
steel anvil and broken up with the hammer; the lead
button carefully picked up with the pliers and brushed, is
then ready for the next process.
The finely crushed slag is washed in water and then
104 ASSAY OF SILVER, .GOLD, MERCURY, ETC. PART III.
examined with the magnifying glass, to see if any small
globules of lead, &c., remain, and if such are found the
safest plan to secure a perfect assay is to repeat the
operation. In assays of no commercial importance the
FIG. 51. (f nat. size.)
fine globules can be separated from the slag by vanning
in water and then adding them to the main globule.
Scorification and Concentration of the Silver Lead.
If the lead button is malleable the scorification can be
proceeded with direct ; but if, on the contrary, it is brittle,
FIG. 52. (Full size.) from one to three g rains of
proof lead and 0'3 grain
borax glass is added to it on
the scorifier, and the ope-
ration carried on as before.
The scorification is best
carried on in a small scori-
fier made of good fine clay, about T %- of an inch in diameter,
of an inch thick in its deepest place, and 1 of an inch
deep in the centre (see fig. 52). It is used in a holder made
of fire clay, which is partially covered with thick, smooth
paper about 2J inches long and with a hollow place in
PART III.
SILVER.
105
the top, in which the scorifier fits (see fig. 53). A piece
of charcoal will also make a good holder, and can be readily
cut to the required shape. FIG. 53. (Full size.)
The scorifier is warmed, and when at
a red heat the globule of silver lead is
added and brought into a state of fusion
by the use of the K.F. Then the
O.F. is used and the heat applied
gently. The fluid litharge soon forms,
and portions of which adhere and glaze
the sides of the cup. The formation of
the litharge is greatly assisted by slowly
turning the assay round and round and
from side to side at a gentle inclination,
and at the same time keeping the flame
at the edge of the bead.
When the litharge has once formed,
it accumulates rapidly, and from five to
ten minutes completes the operation.
If the ore is poor in silver the scorification can be carried
on until what is termed the 6 eye ' appears, i.e. the
small button of lead is nearly covered with litharge and
only just visible. The operator can, after a few experi-
ments, decide when the operation should be discontinued.
When the lead is rich in silver it oxidises very slowly
and assumes a spherical form.
The assay is allowed to cool, and then the scorifier is
broken on the steel anvil and the button carefully brushed.
It is then ready for cupellation.
N.B. Plattner and David Forbes advise scorification
to be partially carried on, on charcoal, after the reduction
of the assay, and then finished on a cupel of coarse bone
ash. The author has found a loss of silver, as well as an
occasional spirting, &c., by the prolongation of the assay on
1 06 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
charcoal after the complete reduction of the assay has
been effected, and for accuracy and despatch he recommends
the above method, as it has been used for some j/ears with
success by himself.
Cupellation.
When an alloy of lead, silver, gold, copper, &c., is
fused in a cupel in a current of air, the lead is readily oxi-
dised and forms a very fusible oxide. The lead parts with
portions of its oxygen to the copper and other base metals.
The oxides thus produced are dissolved and carried down
into the porous cupel in a liquid state by the vitrified
oxide of lead, leaving the silver and gold in the form of a
small globule on the surface of the cupel.
The cupellation is conducted as follows : Any lead
FIG. 54. (Full size.) alloy over 5 grains in weight is best cupelled
in one of the previously prepared cupels
placed in the cupel-holder (see fig. 54). If
the weight is under 5 grains a small cupel
is sufficient, which can be rapidly prepared
by moistening some of the finely powdered
bone ash with enough water to form a dryish
paste. The paste is placed in the steel cupel
mould (see fig. 55), the bottom of which
must either rest on the steel anvil or some
hard solid substance, and a cupel formed by
placing the bolt (fig. 56) on the top of the
mould and applying a few light strokes. The
mould (fig. 57) containing the cupel is now dried slowly over
the lamp, and finally heated to redness, and if no cracks or
flaws appear, and the cupel presents a smooth and regular
surface, the alloy can now be added (it is never advisable
to proceed with the cupellation unless the cupel is found
to be perfect), and a mild K.F. applied until the assay is
PART III.
SILVER.
107
in a state of fusion ; directly it is so the O.F. must be
applied, and the same continued at the outer edge of the
globule, and without touching the assay. A strong
enough heat must be imparted to the bone ash, to
keep the assay .in oxidation without allowing it to become
FIG. 55. (Full size.)
(Full size.)
chilled or quiet. The cupel can also be moved slightly
from side to side, which gives the lead a fresh surface of
clean bone ash to act upon and facilitate the completion
of the operation. It is best to finish the assay about the
centre of the cupel, but at the same time it is FIG. 56.
not absolutely necessary for the accuracy of
the assay.
With a little practice the operator can
tell when the oxidation is nearly finished by
the surfaces of the bead being covered with
iridescent colours (resembling rainbow co-
lours),which only last but amoment,when the
globule rotates and brightens. Directly the
colours disappear the heat should be slightly
raised, to free the bead from the last traces of
lead, and then the assay is cooled down slowly.
In assays very poor in silver the latter precau-
tion is scarcely necessary. In the case of rich ores, alloys, &c.,
much care must be exercised in cooling the bead gradually,
else a violent spurting takes place and small particles of the
silver are thrown out from the bead, and the assay cannot
be relied upon, and it should be repeated. When cool the
bead is removed with the steel pliers from the cupel and
108 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
FIG. 57.
(Full size.)
cleaned from any adherent bone ash, and if too small to
be weighed it must be very carefully detached by a
needle or some other sharp instrument,
and so as not to injure its form. It is
then measured or weighed, according to its
size, but when the bead weighs more than
O'Ol grain it is more correctly estimated
by the balance than if measured. In
case the ore is very poor, and the button
found to be very minute (on scale below
No. 16, or 0*11 per cent.), it is best to
make a duplicate assay and add the first
button to the silver lead on the cupel of the
second assay, and when finished measure
or weigh both together.
The loss of silver by reduction., scorification, and
cupellation can be corrected by comparing the results ob-
tained from the ore or alloy with those obtained by operat-
ing on a carefully weighed piece of proof silver., which is
added to an artificial compound, prepared by the operator
to resemble as nearly as possible the composition of the ore
or alloy which has been assayed. The synthetical assay, so
prepared, must be free from silver, with the exception of
the amount weighed and added ; and it should be fused,
scorified, and cupelled in a similar manner to the native
ore or alloy, and with the same quantity of lead and fluxes.
The difference in weight of the proof silver before
assaying, and what is found afterwards, will represent the
loss of silver, and it should be added to the assay weight
of the ore or alloy which has been assayed, and it may be
considered as the correct loss which has taken place.
Ores and alloys very poor in silver, and so poor that their
weight cannot be readily ascertained by the balance, do not
require any compensation to be made for the loss of silver
in cupellation, &c., as the loss on very small beads is so
PART III. SILVER. 109
minute that it can scarcely be estimated with accuracy,
and even if it could it would be too little to be of any
commercial importance.
Most accurate results will be obtained by making
synthetical assays and following the methods here de-
scribed, and the student will find that by adopting the
same he can easily make his assays, check them himself ,
and have perfect confidence in the results he obtains.
Synthetical assays entail more labour and time than
that of using tables which have been compiled by authorities
on the subject; but it ensures great accuracy, owing in a
great measure to the different ways in which different
operators use the blowpipe, also to the degrees of heat,
apparatus, quality of material, and the fuel, &c., employed.
The following tables, with full instructions for their use,
have been compiled by David Forbes, and will be found of
great service to the assay er. 1
' Determination of the Weight of the Silver Globule ob-
tained on Cupellation. As the amount of lead which can,
by the method before described, be conveniently cupelled
before the blowpipe is necessarily limited, the silver
globule which remains upon the bone-ash surface of the
cupel at the end of the operation is, when substances poor
in silver have been examined, frequently so very minute
that its weight could not be determined with correctness
by the most delicate balances in general use.'
The blowpipe balance employed by the author turns
readily with y^Vo ^ a g ram ? but could not be used for
determining weights below that amount.
Grlobules of silver of far less weight than 1 i QO are
distinctly visible to the naked eye a circumstance which
induced Harkort to invent a volumetrical scale based
upon the measurement of the diameters of the glo-
1 See Mitchell's Manual of Practical Assaying, pp. 676-681 ; also
D. Forbes, Chemical News, Nos. 380, 384, 392, 396, 398, and 412.
ICQ r
98'
96-
94'
92-
90-
ASSAY OF SILVER, GOLD, ETC. PART III.
bules, which scale in practice has been found
of very great utility in the blowpipe assay
of silver.
The scale for this purpose which is em-
ployed by the author is shown in full size in
the annexed woodcut.
This figure (5 8) represents a small strip of
highly polished ivory about 6^ inches long,
f inch broad, and |- inch in thickness, on
which are drawn, by an extremely fine point,
two very fine and distinct lines emanating
from the lower or zero point, and diverging
upwards until, at the distance of exactly 6
English standard inches, they are precisely
To~o P ar t s f an inch apart. This dis-
tance (6 inches) is, as shown in wood-
cut, divided into 100 equal parts by cross
lines numbered in accordance from zero up-
wards. It is now evident, if a small globule
of silver be placed in the space between
these two lines, using a magnifying glass
to assist the eye in moving it up or down
until the diameter of globule is exactly con-
tained within the lines themselves, that we
have at once a means of estimating the dia-
meter of the globule itself, and therefrom are
enabled to calculate its weight.
As the silver globules which cool upon
the surface of the bone-ash cupel are not
true spheres, but are considerably flattened
on the lower surface, where they touch and
rest upon the cupel, it follows that the weight
of globules corresponding in diameter to the
extent of divergence at the different degrees
of the scale cannot be calculated directly
PART III. SILVER. 1 1 1
from their diameters as spheres, but require to have
their actual weight experimentally determined in the same
manner as employed by Plattner.
The table appended on next page has been calculated by
the author, and in one column shows the diameter in English
inches corresponding to each number or degree of the scale
itself, and in the two next columns the respective weights
of the flattened spheres which correspond to each degree
or diameter ; for convenience these weights are given in
the different columns in decimals, both of English grains
and of French grammes.
These weights are calculated from the following data,
found as the average result of several very careful and
closely approximating assays, which showed that globules of
silver exactly corresponding to No. 95 on this scale, or
O038 inch in diameter, possessed a weight of 0*0475573
grain, or 0*003079 gramme. From this the respective
weights of all the other numbers or degrees on this scale
were calculated, on the principle that solids were to one
another in the ratio of the cubes of their diameters.
This mode of calculation is not, however, absolutely correct
in principle, for the amount of flattening of the under sur-
face of the globule diminishes in reality with the decreasing
volume of the globule. In actual practice, however, this
difference may be assumed to be so small that it may be
neglected without injury to the correctness of the results.
The smaller the diameter of the globule, the less will
be the difference or variation in weight in descending the
degrees of this scale, since the globules themselves vary in
weight with the cubes of their diameters ; for this reason,
also, all such globules as come within the scope of the
balance employed should be weighed in preference to
being measured, and this scale should be regarded as more
specially applicable to the smaller globules beyond the
reach of the balance.
J 1 2 ASSAY OF SILVER, GOLD, MERCUEY, ETC. PART III.
No. on Scale
Greatest Diame-
ter in Inches
Weight of Globule
in Grains
Weight of Globule
in Grammes
1
0-0004
0-00000005
0-000000003
2
0-0008
0-00000044
0-000000028
3
0-0012
0-00000149
0-000000090
4
o-ooio
0-00000355
0-000000229
5
0-0020
0-0000009
0-00000044
6
0-0024
0-0000119
0-00000077
7
0-0028
0-0000190
0-00000120
8
0-0032
0-0000284
0-00000184
9
0-0030
0-0000403
0-00000202
10
0-0040
0-0000554
0-00000359
11
0-0044
0-0000730
0-00000478
12
0-0048
0-0000958
0-00000020
13
0-0052
0-0001218
0-00000789
14
0-0050
0-0003522
0-00000985
15
o-ooeo
0-0001872
0-00001203
10
0-0004
0-0002272
0-00001471
17
0-0008
0-0002725
0-00001704
18
0-0072
0-0003234
0-00002094
19
0-0070
0-0003804
0-00002403
20
0-0080
0-0004437
0-00002872
21
0-0084
0-0005137
0-00003327
22
0-0088
0-0005900
0-00003823
23
0-0092
0-0000748
0-00004307
24
0-0090
0-0007008
0-00004904
25
o-oioo
0-0008007
0-00005011
20
0-0104
0-0009749
0-00000311
27
0-0108
0-0010918
0-00007008
28
0-0112
0-0012170
0-00007883
29
o-oiio
0-0013528
0-00008758
30
0-0120
0-0014970
0-00009090
31
0-0124
0-0010524
0-00010098
32
0-0128
0-0018170
0-00011077
33
0-0132
0-0019934
0-00012817
34
0-0130 0-0021801
0-00014114
35
0-0140
0-0023780
0-00015397
30
0-0144
0-0025879
0-00010755
37
0-0148
0-0028097
0-00018190
38
0-0152
0-0030437
0-00019705
39
0-0150
0-0032903
0-00021302
40
o-oioo
0-0035550
0-00022983
41
0-0104
0-0038230
0-00024751
42
0-0108
0-0041090
0-00020000
43
0-0172
0-0044111
0-00028553
44
0-0170
0-0047250
0-00030589
PART III.
SILVER,
113
No. on Scale
Greatest Diameter
in Inches
Weight of Globule
in Grains
Weight of Globule
in Grammes
45
0-0180
0-0050546
0-00032725
46
0-0184
0-0053991
0-00034955
47
0-0188
0-0057590
0-00037285
48
0-0192
0-0061344
0-00039716
49
0-0196
0-0065258
0-00042250
50
0-0200
0-0069335
0-00044890
51
0-0204
0-0073581
0-00047638
52
0-0208
0-0077799
0-00050495
53
0-0212
0-0082580
0-00053464
54
0-0216
0-00873438
0-00056549
55
0-0220
0-00922854
0-00059748
56
0-0224
0-0097412
0-00063067
57
0-0228
0-0102725
0-00066506
58
0-0232
0-0108228
0-00070021
59
0-0236
0-0113922
0-00073753
60
0-0240
0-0119815
0-00077570
61
0-0244
0-0125901
0-00081513
62
0-0248
0-0132119
0-00085588
63
0-0252
0-0138901
0-00089797
64
0-0256
0-0145440
0-00094141
65
0-0260
0-0152311
0-00098623
66
0-0264
0-0159472
0-00103245
67
0-0268
0-0166828
0-00108010
68
0-0272
0-0174414
0-00112918
69
0-0276
0-0182220
0-00117974
70
0-0280
0-0190256
0-00123177
71
0-0284
0-0198529
0-00128535
72
0-0288
0-0207035
0-00134041
73
0-0292
0-0215782
0-00139704
74
0-0296
0-0224469
0-00145525
75
0-0300
0-0234010
0-00151504
76
0-0304
0-0243496 '
0-00157645
77
0-0308
0-0253224
0-00163950
78
0-0312
0-0263228
0-00170422
79
0-0316
0-0273484
0-00177060
80
0-0320
0-0284000
0-00183869
81
0-0324
0-0294789
0-00190852
82
0-0328
0-0305838
0-00198008
83
0-0332
0-0317162
0-00205340
84
0-0336
0-0328768
0-00212851
85
0-0340
0-0340649
0-00220549
86
0-0344
0-0349739
0-00228400
87
0-0348
0-0364422
0-00235938
88
0-0352
0-0378008
0-00244730
114 ASSAY OF SILVEE, GOLD, MERCUKY, ETC. PART III.
No. on Scale
Greatest Diameter
in Inches
Weight of G-lobule
in Grains
Weight of Globule
in Grammes
89
0-0356
0-0390138
0-00253168
90
0-0360
0-0404368
0-00261797
91
0-0364
0-0417943
0-00270790
92
0-0368
0-0431930
0-00279642
93
0-0372
0-0446162
0-00288860
94
0-0376
0-0460718
0-00298279
95
0-0380
0-0475573
0-00307900
96
0-0384
0-0465239
0-00317728
97
0-0388
0-0506249
0-00327759
98
0-0392
0-0522069
0-00338020
99
0-0396
0-0538215
0-00348452
100
0-0400
0-0554688
0-00359138
Silver Assay. Cupellation Loss. This term is ap-
plied to indicate a minute loss of silver, unavoidably
sustained in the process of cupellation, which arises from a
small portion of that metal being mechanically carried
along with the litharge into the body of the cupel. The
amount of this loss increases with the quantity of lead
present in the assay (whether contained originally in the
assay or added subsequently for the purpose of slagging off
the copper, &c.); it is relatively greater, as the silver
globule is larger, but represents a larger percentage of the
silver actually contained in the assay, in proportion as the
silver globule obtained diminishes in size. It has, however,
been experimentally proved that in assays of like richness
in silver, this loss remains constant when the same
temperature has been employed, and similar weights of
lead been oxidised in the operation.
In the blowpipe assay this loss is not confined to the
ultimate operation of cupellation, but occurs, though in a
less degree, in the concentration of the silver lead, and in
the previous scorification of the assay, had such operation
preceded the concentration. The total loss in the blow-
pipe assay is found, however, to be less than in the ordinary
PART III.
SILVER.
115
muffle assay, since in the latter case the whole of the
oxidised lead is directly absorbed by the cupel.
In mercantile assays of ore it is not customary to pay
attention to the cupellation loss, and the results are usually
stated in the weight of silver actually obtained. Where,
however, great accuracy is required, especially when the
substances are very rich in silver, the cupellation loss is
added to the weight of the silver globule obtained, in order
to arrive at the true percentage.
The amount to be added for this purpose is shown in
the annexed table, which is slightly modified from Platt-
ner s :
Actual Per-
centage of
Silver found
by Assay
Cupellation Loss, or Percentage of Silver to be added to the actual per-
centage found by assay in order to show the true percentage of silver
contained in same, the entire amount of lead in or added to the assay
being the following multiples of the original weight of assay :
1
2
3
4
5
6
8
11
13
16
99-75,
99-5 /
0-25
0-32
0-39
0-45
0-50
90
0-22
0-29
0-36
0-42
0-47
0-69
0-83
80
0-20
0-26
0-33
0-3^
0-44
0-64
0-75
70
0-18
0-23
0-29
0-35
0-40
0-58
0-68
0-82
60
0-16
0-20
0-26
0-30
0-36
052
0-61
0-74
50
0'14
0-17
0-23
0-26
0-32
0-46
0-54
0-65
40
0-12
0-15
020
0-22
0-27
0-39
0-46
0-55
0-62
35
0-11
0-13
0-18
0-18
0-25
0-36
0-42
0-50
0-57
30
o-io
012
0-16
016
0-22
0-32
0-38
0-45
0-51
25
0-09
o-io
0-14
0-14
0-20
0-29
0-34
0-40
0-45
20
0-08
0-09
0-12
012
0'17
0-25
0-29
0-35
0-39
0-45
15
0-07
0-08
o-io
O'll
0-15
0-20
0-23
0-28
0-32
0-37
112
0-06
0-07
0-09
o-io
0-13
0-17
0-19
0-23
0-26
0-32
10
0-05
0-06
0-08
0-09
0-11
0-15
0-17
0-20
0-23
0-27
! 9
0-04
0-05
0-07
0-08
o-io
0-14
0-16
0-18
0-21
0-25
! 8
0-03
0-04
0-06
0-07
0-09
0-13
0-15
0-16
0-18
0-22
! 7
0-02
0-03
0-05
0-06
0-08
0-12
0-13
0'14
0-16
0-20
6
o-oi
0-02
0-04
0-05
0-07
o-io
O'l]
0-12
014
0-17
5
o-oi
0-03
0-04
0-06
0-09
o-io
O'll
0-12
0-14
4
0-02
0'03
0-05
0-07
0-08
0-09
o-io
0-11
3
o-oi
0-02
0-04
0-05
0-06
0-07
0-08
0-09
2
o-oi
0-03
0-04
0-04
0-05
0-06
0-07
1
o-oi
0-03
0-03
0-04
0-04
005
116 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
The use of the above table is best explained by an
example, as the following : An assay to which there had
been added, in all, five times its weight of assay lead, gave
a globule of silver equivalent to 6 per cent. Upon refer-
ring to the table, it will be seen that the cupellation loss
for this would be 0'07 ; consequently the true percentage
of silver contained in the assay would be 6*07. This table
is only extended to whole numbers, but fractional parts
can easily be calculated from the same.
To enable the operator to sum up the result of his assays
the author has compiled the following tables for estimating
the amount of gold or silver in one ton of ore, also the per-
centage found in the 'assay sample' of 1 j grain.
They are arranged for both the ' long ' and ' short '
ton, and have been calculated from the following data :
Avoirdupois.
4 Long ton' . =20cwt. = 2,240 Ibs. =1015 '649 kilogrammes.
< Short ton' . . .=2,000,, = 906'8296
Hundredweight . . = 112 = 50 '78245 ,,
Quarter . . . .= 28,, = 12 -6956144 kilogrms.
Pound . .=16oz. =7,000 grains = 433'4148 grammes.
Ounce . . =16 drams = 437 '5 ,, = 28 '3375
Dram . . . .= 27 '344 = 1 "77108 gramme.
Troy (Precious Metals}.
Pound . .=12oz. =5,760 grains = 373 '096 grammes.
Ounce . . =20dwt. = 480 = 31 '0913
Pennyweight . .. .= 24 ,, = 1 '55457 gramme.
Grain . . . . . . 0'064773 ,,
Owing to the great fluctuation which has of late years
taken place in the value of silver no permanent standard can
be made for its value per ounce, and the assayer should re-
port only the ounces or percentage found, and give the
market value to date of same.
After the weight of the silver has been determined the but-
ton must always be examined to see if it contains any gold (by
dissolving it in nitric acid), and if such is found the weight
of same must be ascertained and deducted from that of the
button, and the percentage of silver estimated accordingly.
PART III.
SILVER.
117
Gold and Silver Tables for calculating the amount of gold
or silver in 1 ton of 2,240 Ibs., or 35,840 ounces, or
15,680,000 grains, using 1^ grain for the assay sample.
Weight of
Ore or Alloy.
Grains
Gave Fine Metal.
Grains
Equivalent per Ton to
Ounces Dec.
Equivalent to
per Cent.
1-5
1-000000
23893-33
66-666
1-5
0-900000
21503-99
59-999
1-5
0-800000
19114-66
53-333
1-5
O'TOOOOO
16725-33
46-666
1-5
0-600000
14335-99
39-999
1-5
0-500000
11946-66
33-333
1-5
0-400000
9557-33
26-666
1-5
0-300000
7167-99
19-999
1-5
0-200000
4778-66
13-333
1-5
o-iooooo
2389-33
06-666
1-5
0-090000
2150-39
- 05-999
1-5
0-080000
1911-46
05-333
1-5
0-070000
1672-53
04-666
1-5
0-060000
1433-59
03-999
1-5
0-050000
1194-66
03-333
1-5
0-040000
955-73
02-666
1-5
0-030000
716-79
01 -999
1-5
0-020000
477-86
01-333
1-5
o-oioooo
238-93
00-6666
1-5
0-009000
215-03
00-5999
1-5
0-008000
191-14
00-5333
1-5
0-007000
167-25
00-4666
1-5
0-006000
143-35
00-3999
1-5
0-005000
119-46
00-3333
1-5
0-004000
95-57
00-2666
1-5
0-003000
71-67
00-1999
1-5
0-002000
47-78
00-1333
1-5
o-ooiooo
23-89
00-06666
1-5
0-000900
21-50
00-05999
1-5
0-000800
19-11
00-05333
1-5
0-000700
16-72
00-04666
1-5
0-000600
14-33
00-03999
1-5
0-000500
11-94
00-03333
- 1-5
0-000400
9-55
00-02666
1-5
0-000300
7-16
00-01999
1-5
0-000200
. 4-77
00-01333
1-5'
o-oooioo
2-38
00-006666
1-5
0-000090
2-15
00-005999
1-5
0-000080
1-91
00-005333
118 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
Gold and Silver Tables continued.
Weight of
Ore or Alloy.
Grains
Gave Fine Metal.
Grains
Equivalent per Ton to
Ounces Dec.
Equivalent to
per Cent.
1-5
0-000070
1-67
00-004666
1-5
0-000060
1-43
00-003999
1-5
0-000050
1-19
00-003333
1-5
0-000040
0-95
00-002666
1-5
0-000030
0-71
00-001999
1-5
0-000020
0-47
00-001333
1-5
o-ooooio
0-23
00-0006666
1-5
0-000009
0-215
00-0005999
1-5
0-000008
0-191
00-0005333
1-5
0-000007
0-167
00-0004666
1-5
0-000006
0-143
00-0003999
1-5
0-000005
0-119
00-0003333
1-5
0-000004
0-095
00-0002666
1-5
0-000003
0-071
00-0001999
1-5
0-000002
0-047
00-0001333
1-5
o-oooooi
0-023
00-00006666
Gold and Silver Tables for calculating the amount of gold
or silver in 1 ton of 2,000 Ibs., or 32,000 ounces, or
14,000,000 grains, using 1^ grain for the assay sample.
Weight of
Ore or Alloy.
Grains
Gave Fine Metal.
Grains
Equivalent per Ton to
Ounces Dec.
Equivalent to
per Cent.
1.5
i-oooooo
21333-33
66-666
1-5
0-900000
19200-00
59-999
1-5
0-800000
17066-66
53-333
1-5
0-700000
14933-22
46-666
15
0-600000
12799-99
39-999
1-5
0-500000
10666-66
33-333
1-5
0-400000
8533-33
26-666
1-5
0-300000
6399-99
19-999
1-5
0-200000
4266-66
13-333
1-5
o-iooooo
2133-33
06-666
1-5
0-090000
. 1920-00
05-999
1-5
0-080000
1706-66
05-333
1-5
0-070000
1493-32
04-666
1-5
0-060000
1279-99
03-999
1-5
0-050000
1066-66
03-333
1-5
0-040000
853-33
02-666
PART III. SILVER.
Gold and Silver Tables continued.
119
Weight of
Ore or Alloy.
Grains
Gave Pine Metal.
Grains
Equivalent per Ton to
Ounces Dec.
Equivalent to
per Cent.
1-5
0-030000
639-99
01-999
1*6
0-020000
426-66
01-333
1-5
o-oioooo
213-33
00-6666
1-5
0-009000
192-00
00-5999
1-5
0-008000
170-66
00-5333
1-5
0-007000
149-33
00-4666
1-5
0-006000
127-99
00-3999
1-5
0-005000
106-66
00-3333
1-5
0-004000
85-33
00-2666
1-5
0-003000
63-99
00-1999
1*6
0-002000
42-66
00-1333
1-5
o-ooiooo
21-33
00-06666
1-5
0-000900
19-20
00-05999
1-5
0-000800
17-06
00-05333
1-5
0-000700
14-93
00-04666
1-5
0-000600
12-79
00-03999
1-5
0-000500
10-66
00-03333
I'd
0-000400
8-53
00-02666
1-5
0-000300
6-39
00-01999
1-5
0-000200
4-26
00-01333
1-5
o-oooioo
2-13
00-006666
1*5
0-000090
1-92
00-005999
1-5
0-000080
1-70
00-005333
1-5
0-000070
1-49
00-004666
1-5
0-000060
1-27
00-003999
1-5
0-000050
1-06
00-003333
1-5
0-000040
0-85
00-002666
1-5
0-000030
0-63
00-001999
1-5
0-000020
0-42
00-001333
1-5
o-ooooio
0-21
00-0006666
1-5
0-000009
0-192
00-0005999
1-5
0-000008
0-170
000005333
1-5
0-000007
0-149
00-0004666
1-5
0-000006
0-127
00-0003999
1-5
0-000005
0-106
00-0003333
1-5
0-000004
0-085
00-0002666
1-5
0-000003
0-063
00-0001999
1*6
0-000002
0-042
00-0001333
1-5
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Class A (b). This class consists only of argentiferous mo-
lybdenite, and decomposes very readily when soda is used.
120 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
The ore is finely powdered, and 1-5 grain is fluxed with
7 '5 grains proof lead, 2-3 soda, and 2 -3 borax glass in a
soda-paper cornet (which has been previously placed in
a charcoal bore), and is heated with a strong E.F.
When the assay is thoroughly fused incline it gently
and allow the lead globules to come out from under the
slag. Treat it with the O.F. for several minutes, until all
the molybdenum is volatilised ; then allow it to cool, and
scorify and cupel as before.
Class A (c). To this class belong bromyrite, cerar-
gyrite, embolite, iodyrite, all ores and furnace products
calcined with salt, amalgamation residues, old test and
cupels, all argentiferous slags, and silver sweeps and
polishings.
Finely powdered ore . . . 1'5 grain.
Borax glass ' . - . . . . I'O ,,
Proof lead t *. . . 7 '5 grains.
The above, after being mixed, is placed in a soda-
paper cornet on charcoal, and fused by a R.F. until all
the silver is combined with the lead, and the slag shows
itself as a perfectly fluid globule. If copper is present-
in the ore the quantity of assay lead must be added
in proportion to the percentage of copper, as stated
under A (a).
Taking all the precautions noted under reduction of
Glass A (a), the assay is soon finished, as the chlorine,
bromine, and iodine unite and form chlorides, bromides,
and iodides of lead, which volatilise, whilst the silver
unites with the lead.
The reduced lead is scorified and cupelled, as described
in Class A (a).
Class A (d). The most important substance of this
class is litharge (lead oxide), which is readily reduced on
charcoal, but generally very poor in silver ; so it is neces-
PART III. SILVER, 121
sary to take a larger amount for assay than is ordinarily
used.
Five times the weight of the usual assay sample 7'5
grains is mixed with 1 grain borax glass and 1 grain soda
in a soda-paper cornet, and treated with R.F. until all the
oxide is reduced and the fluid slag shows no lead globules.
Towards the end of the operation the flame is directed
principally on to the slag ; otherwise the metal may
become too much agitated and cause a loss. The silver
lead thus obtained is then ready for scorification and
cupellation, and it can be proceeded with as described in
Class A (a).
N.E. It is often found necessary to make several assays
of substances of the above class, on account of the very
small amount of silver they contain.
Class A (e). General method adapted to the assay of
a, by c, either to one or all (d, being composed of litharge,
does not come under the head of this assay).
Take finely powdered ore 1/5 grain, and add to it
from five to ten times its FIQ 59 (Fullsize0
weight in finely powdered
litharge (which must be
free from silver). The
excess of litharge is neces-
sary only when the ore con-
tains a large amount of
metallic sulphides ; for ordinary ores 5 times the weight
will be found ample. Add soda 0-7 grain and finely
powdered charcoal 0-5 grain.
Mix intimately and then remove to a small fire-clay
crucible (see fig. 59).
A piece of platinum wire is now bent into the required
form to act as a holder and support to the crucible whilst
it is in the charcoal furnace (see fig. 60).
FIG. 60. (Full size.)
.122 ASSAY OF SILVER, GOLD, MERCUEY, ETC. PART III.
The charcoal furnace (fig. 61) is made out of two sound
pieces of charcoal, and the inside bored out by the large
borer (see fig. 28, appara-
tus), and the blast hole and
escape way made by the small
borer (see fig. 30, apparatus).
For furnace holder see Mer-
cury Assay.
The crucible, already
charged, is placed in the fur-
nace and held in its place by
the platinum wire. The fur-
nace is then held securely by
the holder; the flame is
applied through the blast
hole at first a gentle flame,
then a strong E.F. Flames
will soon be seen to issue from the top hole, and by
looking into the same the operator can see whether the
assay is fused or not. If it is found to be fused, give it a
strong blast for about one minute, and then allow it to
cool. The crucible, when cool, is broken and the lead
button cleaned. The slag must be examined, and if a per-
fect fusion has not taken place the assay must be repeated.
The assay will be finished as described in a.
Class B (a) consists of alloys ready for cupellation
after an addition of lead. The following table will guide
the operator in regard to the quantity of lead required.
The sample to be assayed is either hammered or rolled
out, and from 1 to 2 grains weighed for assay.
A preliminary assay should first be made and an ex-
cess of lead added. After cupelling and ascertaining the
approximate fineness, the assay can be prepared according
to the following scale, and the synthetical also.
PART III.
SILVER.
123
Table of the Amount of Test Lead to be added to Alloys of
Copper and Silver for their Cupellation by the Blowpipe.
FiiienesH of
Silver
Parts of
Lead
t ineness of
Slver
Parts of
Lead
1000
2
750
11
975
4
700
12
950
5
650
13
925
6
600
14
900
7
550
15
875
8
500
16
850
9
100
17
800
10
Take from 1 to 2 grains of the alloy, and, after
adding the amount of lead necessary, place it on a pre-
viously prepared cupel and proceed according to method
described in p. 106 under the head of ' Cupellation.'
The synthetical assay is conducted in the same manner,
and its loss of silver should be added to what is found in
the assay of the alloy, which will give the actual loss ex-
perienced in the manipulation. The button obtained from
the alloy must, after weighing, be always tested for gold
by dissolving it in nitric acid, and if gold is present the
weight of the same is deducted from that of the silver.
In assaying silver bars that are over 950 fine it is
advisable not to take more than 1 grain for assay, and in
all cases where the operator has not had much practice it is
best to only take 1 grain.
Class C (a), consisting of amalgams, is treated first
according to assay of mercury and Class (7, p. 137. The
retorted residue is now assayed according to 6.
(6) Two grains of the precipitated, or retorted, silver
are fused on charcoal with 0*7 grain of borax, and the
button thus cleaned is cupelled as an alloy. See Class B (a).
(c) Consisting of brass, black copper.
Take of alloy 1 grain and mix with 15 times its weight
124 ASSAY OF SILYEE, GOLD, MEECUEY, ETC. PART III.
of lead and 1 grain of borax glass ; melt with a strong
R.F. until a complete fusion has taken place and the silver
lead button has a bright appearance. Then scorify and
cupel according to Class A (a).
(c) Tin and gun metal.
Fuse 1 grain of the alloy with 12 parts assay lead and
0-5 grain dry carbonate of soda and 0'5 grain borax glass.
Place in a soda cornet and fuse in charcoal. First apply a
strong E.F. As soon as the assay is melted, change the
flame to an oxidising one, and continue until all the tin has
become absorbed in the flux.
If any tin is suspected to be still in the alloy, remove
the button and again scorify with a little borax on char-
coal, as tin cannot be cupelled. The button should now be
treated as Class A (a).
(e) Antimony, tellurium, and zinc.
One grain of the alloy is mixed with 5 grains lead
and O5 grain borax glass, and melted on a soda cornet on
charcoal. A strong R.F. is first applied, then an O.F.,
until the lead button appears clear and white. If the
latter does not occur in a few minutes allow the assay to
cool, and repeat the fusion with more lead and borax until
it does. Then finish as in A (a).
(/) Silver-steel and iron not uniting with lead, the
alloy must be first converted into a sulphide of iron by
fusion with sulphur.
The alloy must be broken into fragments, the largest
not to weigh over 0'5 grain.
Take 1 '5 grain alloy fragments.
, , 12'0 grains lead.
,, 1*0 grain borax glass.
,, 0'8 ,, sulphur.
Fuse in a soda-paper cornet on charcoal with the R.F.
until a good fluid globule is formed, then add 1-5 grain
TAUT III. SILVER. 125
more borax glass to complete the slagging of the iron.
Treat with a strong O.F. until the lead is clear and has
a bright surface. Then cool, clean, and treat as in A (a).
((/) Alloys of lead or bismuth.
Take 10 grains and melt with a little borax on char-
coal. Then clean the button, and if it is found brittle
(from an excess of bismuth) add a small quantity of lead
and then scorify and cupel. See A (a).
(Ji) Copper coins, wire, and cement, containing some-
times nickel.
Take 1*5 grain of the alloy and fuse with 10 grains
lead and 0'7 grain of borax glass on charcoal. When the
assay has been fused apply the O.F., to slag as much as
possible of the copper. Clean the button when the borax
and litharge are fully charged with the copper oxide.
Then scorify with 20 grains of lead and 0'5 grain of borax,
as in A (a), and finish the assay as usual.
GOLD.
Grold is nearly ajways found in the metallic state, but
4 never pure.' A good crystal is considered a rarity. The
octahedron and dodecahedron are the most common forms.
Crystals sometimes acicular, through elongation of octa-
hedral or other forms ; also passing into filiform, reticulated,
and arborescent shapes, and occasionally spongiform from
an aggregation of filaments ; edges of crystals often salient.
Cleavage none. Twins : twinning plane octahedral. Also
massive and in thin laminae. The above forms usually
occur in veins or lodes.
In alluvial soils, streams, rivers, and gravel beds gold
is generally found in flattened grains or scales and in
rolled masses.
Hardness = 2-5 3. Spec, gravity =15-6 19*5; 19'30
19*34 when quite pure (Gr. Kose).
126 ASSAY OF SILVER, GOLD, MERCURY, ETC. PAKT III.
Gold is generally alloyed with silver in various propor-
tions, arid pieces from California, Idaho, and Nevada,
U.S.A., have been assayed by the author and found to con-
tain as much as 50 per cent, silver ; whilst the purest native
gold from the same sources that he has examined have
assayed 97 per cent, pure gold and nearly 3 per cent, silver.
Gold is also found combined with copper, iron, bismuth,
palladium, rhodium, and tellurium.
Grold combines with mercury in what is generally
termed gold amalgam.
Gold is also found associated (or as an incidental ingre-
dient) with certain ores containing iron and copper pyrites,
mispickel, blende, and galena.
In metallurgical works the proportions of mercury to
gold in amalgam vary greatly, owing to the size as well as the
purity of the particles of gold which have been brought
into contact with the mercury. The author has found in
reduction works in California that the percentage of
mercury in the gold amalgam there obtained varied from
36 to 85 per cent.
Nearly all metallurgical products from lead, silver, and
copper smelting works contain gold, and especially those
obtained from the smelting of argentiferous lead ores ; but
as a general rule the quantity is too small to pay for extrac-
tion, as in many instances ' a slight trace ' can only be
found by the most careful analysis.
Gold Assay.
The assay for gold, although apparently easy, is de-
cidedly the reverse, and accurate results depend greatly
upon the judgment of the operator in first selecting the
sample and then employing the correct method of assaying
the same.
Gold is separated from its matrix by fusion with lead,
and the button so obtained is scorified in the same manner
PART III. GOLD. 127
as the ores described in the silver assay. Gold alloys are
fused with lead; three times the weight of pure silver
is added, then the assay is cupelled and the button boiled
in nitric acid, which dissolves the silver, leaving the gold
in a fine powder, which is heated to redness and weighed.
In assaying gold ores it is necessary to take a large
quantity for assay, and as such cannot be fused by the
blowpipe the author has adopted the following methods :
The assay of gold is divided into three classes A, B, C.
A. Ores, minerals, furnace slags, mint, and jewellers
sweeps.
B. Gold alloys.
C. Gold amalgams.
A (a). Ordinary gold ores, from which the metal is
extracted by raw amalgamation. Wash 5 Ibs. (80 oz.) in
a batea ; then collect the sulphides, &c. (from which the
lighter portions have been separated by the vanning),
remove them to a flask, and boil in nitric acid; then
filter, and burn the filter paper and insoluble residue
in a small evaporating dish, add twice its weight of lead
and its own weight of borax. (The filtrate can now be
tested for silver, adding a few drops of hydrochloric acid,
and if silver be present it will be thrown down in a white
flocculent cloud as a chloride of silver. The same should
be collected on a filter, and can be weighed after drying care-
fully and then gently fusing in a small porcelain cup that
has been previously weighed, silver, 75*28; chlorine, 24'72.)
Place in a soda-paper cornet and then fuse in the deep bore
on charcoal as in the Silver Assay. Clean the lead button
so obtained, then scorify, and afterwards cupel. Weigh
the button found after cupellation and fuse it on charcoal
with three times its weight of silver ; boil it in a small
flask with nitric acid, and after all action has ceased pour
off the liquor and wash the fine dark powder with distilled
128 ASSAY OF SILVEE, GOLD, MEECUEY, ETC. PART III.
water, add more acid, boil again, wash again, and then re-
move to a small porcelain cup and allow it *to dry slowly
over the lamp ; when it is quite dry heat the cup to a bright
red colour, and then remove the gold (now pure) to the
balance and weigh.
(6) Gold ores consisting of nearly pure pyrites, also
quartz mill concentrations, cannot be washed with safety.
After the mineral has been finely pulverised take from
100 to 1,000 grains, according to the amount of silica
in the ore, and roast it on an ordinary piece of
sheet iron, turned up at the edges (an old worn-out
miner's shovel has often been used by the author), which
has been previously coated with a little moist fire clay ;
heat the sheet iron over a charcoal or coal fire, keeping it
at a dull red heat, and stir continually until the smell of
sulphurous acid is no longer perceptible ; then boil the
roasted ore in nitric acid until all soluble matter in
dissolved, and proceed as in a.
Assays of the above class are generally of great com-
mercial importance, and in such cases make three assays
and take the mean for the report.
(c) Grold sands, such as are found in the rivers and
streams of California and British Columbia, and also on the
sea beach in Oregon, U.S.A., contain a large amount of
specular and titanic iron, and is called ' black sand ' by the
miners. The gold is generally very fine and in the form
of thin laminae. Platinum and iridium are often found
in the same sand.
The above sand cannot be washed for assay. Take 100 to
1,000 grains, according to the amount of black sand in the
ore, and attack with aqua regia in a flask ; boil for about 30
minutes or more, dilute with water, and filter. If gold is
present it will now be held in solution in the filtrate; remove
the filter and evaporate the filtrate to dryness ; then add
a little hydrochloric acid and redissolve the dry salt in
PART III. GOLD. 129
warm water ; add to the solution so formed protosulphate of
iron, which will throw down the gold in the form of a fine
dark precipitate. The precipitate is seldom pure, being
mixed with oxides of iron, and must now be dried in the
filter paper and both burned over the lamp in a porcelain
dish. Then mix the dried precipitate with three times its
weight of lead, and its own weight of borax, and one-half
its volume of soda ; fuse, scorify, and cupel as directed in
a. In case platinum, iridium, &c., are found associated
with the gold an extra amount of pure silver should be
added before cupellation, and the gold button will be found
pure.
(d) Grold from alluvial deposits, ancient and modern
river-beds, and placer washings.
The greater part of the gold obtained from such sources
is usually found to consist of coarse grains, nuggets, &c.,
making it a difficult matter to take a sample for assay.
A large quantity (20 tons or more) should be washed
through the ordinary gold sluice-box (which has rifles or
stops charged with a small quantity of mercury) and the
gold collected ; then a careful sample should be taken of
the tailings or residues and three to five different assays
made. Weigh out 5 Ibs. (80 oz.) of the tailings and wash
carefully in a batea. The concentrated mineral must be
dried, and fused in small portions (about 2 grains at
a time) with twice its weight in lead, and its own weight
in borax, and half its volume of soda, and the assay carried
on as in a.
The coarse gold first obtained should now be weighed
and a sample taken for assay. The assay must be conducted
as described on p. 130 under the head of < Gold Alloys.'
The assay of the tailings or residues must be added
to that of the gold alloy first obtained, and the value per
ton of the whole will be ascertained.
130 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
(e) Furnace slags generally contain a very small per-
centage of gold, which at the same time is so minutely
distributed through the slag that a direct fusion is the
only safe method to employ.
Take 2 grains slag.
,,6 lead.
,, 1 grain borax.
soda.
After a complete fusion in charcoal reduce the lead by
scorification and cupel. The assay is now finished as di-
rected in a.
(/) Mint and jewellers ' sweeps ' are composed of
such various metals and compounds that it is difficult to
select an average sample for blowpipe assay ; therefore
Take 1 00 grains of the sweeps and boil them in a flask
with nitric acid until all the soluble matter is held in
solution. Dry the insoluble matter and the filter, and burn
the latter. After so doing fuse with lead according to
directions in e, and finish as directed in a.
\g) Direct and universal method for assaying gold
ores and minerals, such as telluride of gold, mixed
sulphides with which gold is associated for instance, sul-
phides of arsenic, copper, zinc, bismuth, iron, lead, &c.&c.
Take 1*5 grain of ore, mix with 5 to 10 times its
weight of pure litharge, and assay in precisely the same
way and with the same apparatus as used and described
in the Silver Assay, A (e\ and purify the gold as directed
in p. 127.
B (a). Fine gold, bar and ingot gold, coins and na-
tive gold, without any adhering matrix or foreign sub-
stances.
All the above are capable of direct cupellation after
an addition of lead. The lead must be added in the
following proportions :
PART III.
GOLD.
131
Fineness of Gold
in Alloy
Parts of Lead necessary
to remove the Copper
by Cupellation
Fineness of Gold
in Alloy
Parts of Lead necessary
to remove the Copper
by Cupellation
1000
5
700
27
975
7
650
30
950
9
.000
33
925
11
550
35
900
13
500
36
875
15
400
36
850
17
300
36
825
19
200
36
800
21
100
36
750
24
The gold coin of France is 900 gold to 1 00 copper, and
that of the U.S. of America the same. The British
standard is gold 916*66 and the remainder copper.
Weigh out 1 grain of alloy and 3 grains of pure
silver, and wrap up in a small piece of rolled assay lead
which has been weighed, and cupel on a previously pre-
pared cupel (see fig. 54, Silver Assay). The heat required
is greater than that which is employed in the Silver Assay,
as the alloys of gold, copper, and silver require a high
temperature for cupellation. Grold suffers but a slight
loss by volatilisation. When the cupellation is complete
remove the button with the pliers and clean the lower
surface with a small brush ; then beat the button on the
steel anvil until a thin sheet has been obtained.
The last operation can be facilitated by placing the
assay on a piece of charcoal and heating it to redness and
then beating it out. When thin enough anneal again and
twist the small sheet of alloy into the form of a coil, and boil
in a small flask or test tube with about -J oz. of nitric acid
(of 1'3 specific gravity) for 5 to 10 minutes; then add a little
pure water and pour off the nitrate of silver ; again add J oz.
of nitric acid (of 1'3 specific gravity) and boil until all
action has ceased. Then pour off the acid, add an ounce
K 2
132 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
of pure water, and boil for a minute. Pour off the hot
water and fill the tube with cold water, and remove the
gold into a small pipe-clay crucible by first placing
the crucible on the mouth of the flask or test tube (see
FIG. 61. FIG. 62. fig. 61), then inverting- them both
(Half size.) (Halfsize.) ^ fig '_ ^ The ~ ^ (eyen
if in a fine powder) soon settle to
the bottom of the cup, and it can be
quickly done if the operator will
slightly tap the sides of the tube
with his finger nail, remove the tube
from the crucible, and carefully pour
off the water, and then allow to dry
slowly, and when dry heat the cruci-
ble to a bright redness over the spirit
lamp, and then remove the gold to
the balance and weigh as pure.
If the alloy is only about 800
(or under) fine take 0*7 gr. for as-
say, and cupel first with the neces-
sary quantity of lead, and add the
charge of silver with 2 grains of lead when the cupel-
lation is nearly complete.
Chemically pure gold, even when boiled 3 times in
nitric acid, still retains a trace of silver, and 1,000 parts
of pure gold, after being carefully cupelled and parted,
will weigh 1000*2. The amount is, however, so small
that it is only deducted in the Mint and Gold Assay
Office reports.
(6) Gold nuggets and fine gold dust.
Take 1 grain, and fuse on charcoal with 1 grain borax
and ^ grain nitre, and after the bead is thoroughly cleaned
by the fusion proceed as in B (a). In assaying nuggets
cut them in two, and get an average sample if possible.
PART III. , GOLD. 133
The outside is generally deceptive, and frequently coated
with foreign substances, such as silicates, iron oxides, &c.
(c) Worn-out copper plates that have been used in
gold amalgamation works, copper coins, wire, and cement.
Weigh out 10 grains, and attack with dilute nitric
acid ; after a thorough boiling and decantation, dry the
fine dark residue, add to it pure silver and lead, cupel, and
then finish the assay as in B (a).
(d) Gold containing palladium and not more than 10
per cent, of platinum.
Cupel 1 grain of alloy with 4 grains of silver and the
proper quantity of lead (see table, p. 131). Attack with
nitric acid three times, and the gold residue will be found
pure.
(e) Gold containing more than 10 per cent, of platinum.
Dissolve 1 grain of the alloy in nitro-hydrochloric acid
(3 parts hydrochloric and 1 part nitric acid). Whilst the
solution is still warm add chloride of ammonium to
it, and evaporate the whole to dryness at a moderate
temperature. The dried salt is then washed on a filter with
alcohol of 70 to 80 until a fresh addition of it is no longer
coloured yellow. The gold is by this means dissolved out.
Add water to the alcoholic solution, remove the alcohol by
evaporation, and then precipitate the gold with protosul-
phate of iron according to the methods described in A (c).
(/) Gold containing iridium. Dissolve 1 grain in
aqua regia. The iridium remains behind in the form of a
black powder, which can be washed and dried and the
percentage of iridium estimated. The gold can be esti-
mated as in A (c).
If the alloy contains copper it must be first cupelled
with about 5 parts of lead, and the last trace of lead
removed by fusing it on charcoal with boracic acid.
(#) Gold with platinum and silver.
134 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
Plattner recommends the following plan : When the
silver has to be determined, it must be extracted by sul-
phuric acid. To do this with proper accuracy the alloy
should contain for 1 part of gold and platinum not less
than 1 nor more than 2 parts of silver, because some
platinum seems to dissolve with more silver. When silver
is lacking, an accurate quantity of pure silver must be
added, and if gold is lacking the alloy must be molted
with pure gold, to secure the necessary proportions of the
metals.
One grain of the alloy being weighed out and brought to
the proper proportions by fusing it with gold or silver and
borax glass on coal, the button is beaten as thin as pos-
sible, heated to redness, and rolled up.
After being weighed, to see that no mechanical loss
has occurred, it is covered with concentrated sulphuric
acid in a porcelain vessel and boiled for 10 minutes. After
cooling, the acid solution containing sulphate of silver
is decanted, and the porous metallic residue boiled five
minutes longer with fresh acid to complete the separa-
tion of the silver. The remaining roll is boiled with
distilled water, dried, ignited, and weighed ; the difference
gives the weight of silver. The gold and platinum are
then separated according to B (d).
(h) Grold containing rhodium.
Weigh 1 grain of alloy, dissolve in aqua regia, and
precipitate the gold with protosulphate of iron, as in A (c).
The rhodium remains in solution.
(i) Gold with lead, bismuth, gun metal, antimony,
zinc, brass, &c., is assayed according to Class B in Silver
Assay. If much antimony or zinc is present the alloy
should be fused on charcoal with borax before cupellation.
(j) A rapid method of making an approximate assay
of gold coins, nuggets, gold dust, or bullion.
PART III. GOLD AND MERCURY. 135
Take 1 grain of the alloy, melt it with 4 grains of
silver, 1 grain borax, 0*5 grain nitre, on charcoal.
After a thorough fusion beat it out and dissolve as
usual in nitric acid. The assay can be made in a few
minutes, and will be within 5 to 10 thousandth of the true
standard.
C (a). Gold amalgams are first retorted according to
Class C in assay of mercury. Then the alloy is fused
with a small quantity of borax and nitre on charcoal.
One grain of the fused metal is weighed out and treated
as in B (a).
MERCURY.
Mercury occurs in small fluid globules scattered
through its gangue.
Specific gravity =13*5 6. Lustre metallic. Colour
tin white. Becomes solid at 39 Fahr. below zero, and
crystallises in octahedrons. Volatilises at 64 Fahr. and
entirely so at 662 Fahr.
The rocks affording the metal and its ores are mostly
clay shales or schists of different geological ages.
Cinnabar, or sulphide of mercury.
Contains sulphur 13*8 per cent., mercury 86*2 per
cent.
Cinnabar is of a bright red or reddish brown colour,
and is sometimes impure from clay, oxide of iron, and
bitumen.
Tiemannite, or selenide of mercury.
Contains selenium 28*4 per cent., mercury 71*6 per
cent.
Calomel, or flour mercury.
Contains chlorine 15-1 percent., mercury 84*9 per cent.
Mercury is also found combined in various proportions
with sulphides of zinc, and also with iodine.
136 ASSAY OF SILVEE, GOLD, MERCURY, ETC. PART III.
Amalgams.
Mercury with gold, silver, and copper in the form of
amalgam has been frequently found in nature, but the
proportions vary greatly in different localities, and no
correct formula has yet been arrived at.
In metallurgical products mercury is obtained in
combination with many metals, the principal of which are
gold, silver, copper, lead, bismuth, zinc, iron, tin, &c., and
under certain conditions it combines with sodium and
potassium.
Amalgams of silver, bismuth, &c., are extensively used
by dentists.
In the practice of medicine mercury is largely used,
the general forms being metallic, subchloride, chloride, and
oxide. Mercury is nearly always determined by distillation,
but before making an assay of its ores the operator should
examine with great care the ore in question with regard
to metallic globules of mercury, and if such are found to
exist (which is frequently the case, especially in the ores
from Californian mines) several ounces of the ore should
be weighed, and then crushed up and vanned carefully in
a horn spoon, or porcelain bowl, and the metallic mercury
collected on blotting or filter paper, which, when dry, weigh,
and add the percentage so found to what is afterwards
obtained by assay from the remainder.
The residue both of water and crushed ore must be all
carefully saved, the water evaporated, and when dry mix
and take a sample for assay.
Assay for Mercury.
The compounds to be examined are divided into three
classes, and will be called A, B, C.
PART III. MERCUKY. 137
Class A,
Consisting of metallic mercury.
,, cinnabar (artificial slate forms what is called
vermillion).
, , tiemaimite.
,, sub-oxide.
,, protoxide.
,, mixed sulphides, &c.
Class B.
Consisting of calomel (sub-chloride).
chloride of mercury (corrosive sublimate).
,, iodide of mercury.
Class C.
Consisting of amalgams of gold, silver, copper, lead, zinc,
tin, &c. &c.
Class A. The assay is conducted as follows :
Keduce the ore to a fine powder, so that the sample to
be assayed will all pass through a sieve of 2,000 holes to
the linear inch. Weigh out from 10 to 20 grains of ore,
according to its richness; intimately mix with 5 to 10
times its weight of finely powdered litharge, and distil in
a small glass retort over the spirit lamp.
Eetorts of the following size and shape (see fig. 63)
have been found to give very accurate results, and can be
made by the operator from hard flint glass tubing by
closing one end over the lamp and then bending it, when
heated, to the required angle. The retort a, or cup, is
made f inch in length, and neck b of same f inch, and J
inch in diameter. The neck is fitted into a good tight
cork, and placed firmly in the top of a glass tube c of
about 2 J inches in length and T %- of an inch in diameter,
tapering at the bottom to J of an inch. The tube is also
bent slightly, to facilitate the collection of mercurial
vapour in the receiver d. The end of the tube is kept
immersed during the heating of the assay in a small cup
or capsule containing water, and, as the operation occupies
138 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
only a few minutes, the retort and condensing tube can
be held with a small pair of wooden tongs without any
inconvenience.
FIG. 63. (Full size.)
Before the retort is used expel all the moisture by a
thorough drying. The above-shaped retorts are easily
charged by pouring in the ore and litharge from a small
mixing spoon, and then connecting it by means of the cork
'with the condensing tube.
The retort is heated very gradually at first over the
spirit lamp, and finally the heat is raised until the assay is
fused, and the glass softens and nearly melts. The greater
portion of the mercury will be found in the receiving cup,
but small particles will generally be found in the condens-
ing tube. Heat the tube slightly, which has the effect of
bringing the minute globules of mercury together ; then
remove them carefully with a feather and add them to the
globules in the cup. The retort and its fused contents
should now be broken up in a horn spoon or porcelain dish,
in which a small quantity of water has been previously
added, and after vanning examine carefully with a magnify-
PART III.
MERCURY.
139
ing glass, to see if any globules can be found. If they are
the assay should be repeated.
Slightly heat the receiving cup over the lamp, taking
care to have it half full of a FIG. 64. ( size.)
water. The fine globules of
mercury will then unite into
one globule. Pour off the
water and dry the mercury
with blotting paper, and re-
move to a small weighing
cup and ascertain its weight
on the balance. The mer-
cury so obtained can be con-
sidered pure.
Class B. Cannot be re-
duced by litharge alone, and
a different reducing agent as well as shaped retort must be
employed. Take of the finely powdered ore or product 10
grains, and mix it with about 3 times its volume of neutral
potassium oxalate and 1 volume of potassium cyanide,
and distil in a retort of the following description (see fig.
64) : A small bulb-shaped retort a, constructed of thick,
hard flint glass, about ^ inch in diameter at its widest
part and j inch in depth ; length of neck b about J inch ;
diameter of the latter about } inch. The neck is fitted with
a good cork and placed firmly on the top of a glass tube
about 2 J inches in length, and -fa of an inch in diameter
at the top, tapering at the bottom to J of an inch. The
mixture having been placed on the retort, the heat is
applied very slowly and with great care at first, to avoid
the rapid reaction which would otherwise take place. The
distillation only occupies a few minutes, and the assay
should be completed and the mercury collected and
weighed with all the precautions mentioned in Class A.
140 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
Class G. Native and artificial amalgams, as well as
dentists' products, are often so hard and compact, as well
as mixed with lead, bismuth, zinc, copper, &c., that a
correct determination cannot be arrived at by direct
distillation, owing to the swelling, spitting, and spurting
that take place soon after the application of heat. An
approximative test should be made on charcoal or in a
small crucible or glass tube, and if the spurting is found
to be so violent that the amalgam cannot be distilled
without loss, it should be crushed up in the agate mortar
and then placed in the retort for distillation. In many
cases the latter plan is most difficult, and in some im-
possible without losing a large, portion of the sample. In
such a case weigh out one equal part of pure mercury,
mix it with the assay sample, and then crush it in the
agate mortar. The amalgam will then be found to be in
a semi-fluid condition, in which state remove it to the
iron retort, and the mercury can be evaporated and
collected without danger of loss in spitting, and the
weight of the mercury added deducted from the total found.
In assaying amalgams make two assays.
1st. Distil the amalgam, then condense and collect
the mercury, and weigh.
2nd. Subject the amalgam to the blowpipe flame either
in an open cup or dish, and take the loss of weight to be
mercury. The heat never to be sufficient to fuse the
retorted metal, else a loss will arise from the volatilisation
of lead, zinc, silver, &c., all of which are frequently found
combined with mercury.
The last method will be found to be very accurate
when the amalgams consist of nearly pure silver or gold
combined with the mercury, but if other metals exist with
them the results are very uncertain.
It serves, however, not only as an approximate assay,
but as a check on the distillation assay.
PART III. MERCUEY. 141
The retorts used for the determination of the amount
of mercury contained in amalgams must be differently
constructed to those which are used for Classes A and 5, and
are best made of cast steel, which is afterwards turned
in the lathe to the required form.
FIG. 65. (f size.)
The retort is made 1 inch in height, which includes
the cup and cap ; the neck about 2 inches in length, having
a gentle taper towards the end, w^hich is made to fit into
a good cork which has been previously placed in the glass
condenser. (See fig. 65, cross section of the steel re-
tort with glass condenser.)
Fig. 66, view of the cup and distillation pipe of the
amalgam retort.
Fig. 67, view of the FlG - 66 - ( Ful1 size -)
receiving cup of the
amalgam retort.
Fig. 6 8, view of the
glass condenser.
Ten to 30 grains of
the amalgam to be
examined is weighed,
wrapped up in a small
piece of tissue paper,
and (the weight of ash,
contained in a similar piece of the same paper, must
always be determined in a quantitative assay) placed
142 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
in the receiving cup (fig. 67). The cap is now placed
,^^7- firmly on. The joint being perfectly air-tight,
no luting is necessary.
The condenser (fig. 68) is attached, and
the retort placed in the charcoal furnace, which
has now to be held firmly by the holder. See
fig. 69, a side view of the holder and charcoal furnace,
showing end of retort.
FIG. 68. (Full size.)
Fig. 70, a top view of the charcoal furnace and
holder.
The furnace is now brought near the blowpipe lamp
FIG. G9. (Half size.)
and the end of the condenser kept immersed in water con-
tained in a small porcelain crucible.
The heat is applied very quietly at first, but in a few
minutes a strong R.F. may be applied through the hole
PART III.
MERCURY.
143
in the lower part of the furnace. Flames will soon
be seen coming out of the top hole of the furnace, and
the retort will be found to be red hot. Keep it so for
about two minutes, then cease blowing and allow the retort
to cool.
See fig. 71, sectional view of blowpipe stand and
lamp, with flame playing on the amalgam retort, which
has been placed in the charcoal furnace ; also a view
showing the position of the condenser and receiver of the
mercurial vapour.
FIG. 70. (Half size.)
The whole operation does not take ten minutes, and
although the retort may appear large, the operator will
find no difficulty even in obtaining a white heat if
necessary ; and in a few minutes the assay is completed.
The mercury is collected and weighed according to the
methods laid down in Class A*
Most accurate results will be obtained by following the
above instructions.
In Plattner's * Manual of Qualitative and Quantitative
Analysis with the Blowpipe,' by Prof. T. Kichter, and
translated by Henry B. Cornwall, and published 1873,
144 ASSAY OF SILVER, GOLD, MERCURY, ETC. PABT III.
on p. 509 will be found the following under the head
of ' Assay for Mercury : '
' This assay, essentially the same as that proposed
by Domeyko and described in the " Berg- und Hiittenm.-
Zeitung," 1845, No. 20, is very simple and exact/
A glass tube, about 3 lines in diameter and 7 to
8 inches long, of not too thin glass, is bent as shown
FIG. 71. 1 (I size.)
in fig. 72, and closed at one end, leaving the shorter
arm a 1J to 2 inches long.
The tube is thoroughly dried, and then from 500 to
3,000 milligrammes of finely powdered ore, according to its
richness, intimately mixed with 5 to 10 grammes litharge,
1 The three different retorts, also charcoal holder, all originally de-
signed by the author, were made by L. Cassella, 147 Holborn Bars, E.G.,
where similar ones can now be procured.
PART III. MERCURY. 145
being introduced into it, the lower end is gradually heated
over the spirit lamp until the whole mass is fused and
the glass begins to soften. The moisture that may be
present condenses in the middle of the tube, while the
mercury will settle as a thin film, sometimes 1 scarcely
perceptible, on the sides of the glass (see fig. 72).
When all of the mercury has been sublimed the tube is
carefully heated, so as to concentrate the mercury as much
as possible to a ring at 6 ; the tube is allowed to cool, cut
off with a file close to the ring, and the mercury then
brushed together to one drop and transferred to a weighed
capsule.
FIG. 72. (Half size.)
In this way 0*05 per cent, of mercury can be very
readily determined, and the nature of the gangue has no
influence upon the result. The excess of litharge serves
not only to oxidise the sulphur and selenium, but also to
remove the arsenic, antimony, and bitumen so frequently
found in ores of mercury, and the resulting metal is so
pure that it can be very easily and perfectly united in one
drop.
COPPER.
Copper is a metal having a metallic lustre and of a
copper-red colour. It has a streak, metallic shining, and
is ductile and malleable with a hackly fracture.
Hardness, 2*5 to 3. Specific gravity, 8*838 when native.
146 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
The principal ores of copper are
'Copper glance . containing 797 per cent, copper.
Chalcopyrite . ,, 34 '4 ,,
Bornite . ,< . . 557
Bournonite . . ,, 13 '0 ,,
iFahlerz . . . ,, 30 to 48
Covelline . . . - . 667
I Wolfsbergite , ,, 24 '9 ,,
IDomeykite (copper arsenide),, 71 '6 ,,
- Copper regulus, copper speiss, &c.
^ f Red copper .. . containing 887
|| I Malachite ',. ! ., 57 '3
i1 Azurite . . 55'1
^ ^ Cyanosite. . ,^ ,, 25 '3
.| g | Phosphate of copper ,, 30 to 56 ,,
"I | JArseniate. . , . ,, 25 ,, 50
^ ^ Chromate, vanadate, and silicate
^ of copper, slags, &c.
Assay.
The assay for copper is divided into three classes,
called A, B, and C.
Class A .
Consists of ores and products in which the copper is com-
bined with volatile substances, such as sulphur, arsenic,
and selenium.
Clans B.
Consists of ores and products in which the copper exists as
an oxide or is combined with chlorine.
Class C.
Consists of alloys containing copper.
Copper is separated by the blowpipe from its matrix or
compounds by first freeing it from its combinations with
PART III. COPPEK. 147
sulphur, &c., by roasting the finely crushed substance with
powdered charcoal or graphite. The oxidised mineral is
then fused with soda, borax glass, and a small quantity of
test lead. The soda reduces the copper oxides to metal,
and the lead assists in the collection of the copper in the
shape of a globule. The alloy of lead and copper is then
fused on charcoal with boracic acid, which dissolves the lead
and leaves a copper button.
The fire assay of copper is of great use to the smelter
and miner. By observing the behaviour of the small
assay sample under treatment, and by examining the copper
prill or button obtained by the assay, a conclusion can be
arrived at in regard to the quantity as well as the quality
of the copper which will be produced from similar ores
or products treated on a large scale in smelting works.
The fire assay always yields a smaller percentage of
copper than that which is found by analysis or by assays
made by the volumetric methods. With a little practice
and care the following methods of assaying have been
found to give equally as good results as the German fire
assay. The latter is considered more accurate than the
English fire assay :
Class A. Take 1J grain of the finely powdered ore
and mix in the agate mortar with 3 to 4 FIG. 73.
times its volume of dry charcoal powder,
or with | grain graphite powder (N.B.
the graphite used in an ordinary lead
pencil answers very well) ; place the assay in a small clay
capsule.
The clay capsule should be painted with reddle before
using (see fig. 73).
The assay is now ready for roasting.
Place the roasting cup on the holder above the lamp
flame (see fig. 74).
L 2
148 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III
(The best fuel to use is common methylated spirit, as
oil is apt to cover the cup with lampblack.)
Place over the roasting cup a small hollow cone made
of thin sheet iron, which confines the heat and makes a
mild form of a furnace.
The roasting is nearly complete in 10 minutes. Kemove
the assay again to the agate mortar, and mix it with 3 times
FIG. 74. (Half nat. size), its volume of dry powdered charcoal, or
J a grain of graphite powder, and place
it over the lamp as before, and conti-
nue the heat until no fumes of sulphur
or arsenic are observed after stirring
with a small piece of iron wire. For
the success of the assay it is neces-
sary that all the sulphur should be eli-
minated ; therefore, to be certain of
the assay, remove the cone, turn the
support partly to one side and a little
below or on a level with the lamp wick, and apply to the
bottom of the cup a strong O.F. for a few moments.
The copper is now in the state of oxide mixed with
various other metallic oxides and earthy matters, and the
assay will be finished according to the plan adopted in
Class B.
Class B. The roasted ore, product, or mineral, having
been reduced to the state of a fine powder, is mixed in
the following proportions with a reducing flux :
Ore 1 .... 1 '5 grain.
Soda . . . 3'0 grains.
Borax glass . . 0'5 grain.
Test lead . . . 0'5
1 Ore belonging to Class A that has been weighed once need
not be so again.
PART III. COPPER. 149
The assay is then removed to a small soda-paper
cornet, previously placed in a deep bore on a piece of char-
coal. A mild R.F. is first applied, and then finally a
strong flame to unite all the metallic globules. This
having been accomplished, the assay is allowed to cool,
and the button is separated from the slag by enclosing it,
in a piece of thick paper and gently hitting it on the steel
anvil with the hammer, after which it is treated as Class C.
Class C. (a) Alloy of copper and lead.
The button obtained from Class B is now ready for
refining, and will be assayed in a similar manner to a
copper and lead alloy, viz. a small hole is made in a
piece of sound charcoal, and boracic acid, equal in weight
to the crude button containing copper, is melted on the
charcoal. When the boracic acid is in a state of fusion
the copper button is added. The E.F. is applied until
the button and flux are dissolved ; then an O.F. is applied,
and continued until the lead has absorbed oxygen and
has been taken into combination with the borax, and the
remaining copper assumes a greenish colour.
The copper button is allowed to cool, and is separated
from its surrounding impurities by folding it in a thick
piece of paper and striking it gently on the steel anvil
with a hammer.
The slag should be examined, to see if it has a reddish
colour ; if it has, it must be remelted with a strong R.F.
on charcoal, and any globule of copper so obtained added
to the larger button. A pure button of copper should be
malleable.
If the copper ore or compound contains either gold
or silver, they will be found alloyed with the button so
obtained. To test for the above the button is cupelled
and treated according to directions given in the Silver
Assay.
150 ASSAY OF SILVER, GOLD, MKRCURY, ETC. PART III.
(6) Alloy of copper and antimony.
Weigh out 1J grain of the alloy and fuse in a small
bore on charcoal. The O.F. alone is used after the assay
melts, and it is continued until the antimony is burnt
away.
The button obtained is then beaten on the anvil, and
it should be malleable and not fracture if hammered out
from two to three times its diameter. The button should
also be tested for gold and silver.
N.B. Alloys of copper and tin, consisting of bronze,
bell and gun metal, &c., also alloys consisting of copper
with iron, nickel, cobalt, zinc, and bismuth, and sometimes
containing lead, antimony, and arsenic, have afforded Platt-
ner results not sufficiently satisfactory for a quantitative
assay. The author has also experienced similar trouble
in the quantitative separation of copper from the above
alloys, and at present he cannot recommend any method
to be used by the blowpipe beyond a qualitative determi-
nation.
LEAD.
Lead has occasionally been found native, but only in
small quantities in the form of thin plates and small
globules. It has a hardness of 1*5 and a specific gravity
of 11*44 when pure, with a metallic lustre and a lead-
grey colour, and is both malleable and ductile.
The ores of lead are numerous ; the principal one, called
galena, contains, when pure, lead 86'55 per cent, and sul-
phur 13-45 per cent.
For the purposes of assaying the ores of lead by the
blowpipe the method adopted has been divided into two
classes, according to the composition of the ore to he ex-
amined, and will be called A and B.
PART III. LEAD. 1,51
Class A. Comprises galena and all leader es contain-
ing either arsenic, phosphorus, or sulphur.
Class B. Comprises all ores of lead and plumbi-
ferous substances which are free from sulphur and
arsenic, or contain only traces of the latter. Litharge,
carbonate of lead and minium, are the chief substances
which come under this class.
Assay.
Lead is extracted from its matrix by fusing the finely
powdered mineral with metallic iron and a fluxing and
reducing agent in a small crucible placed in the charcoal
melting furnace. The earthy matters and non-reducible
oxides and sulphides are slagged off, and a button of
metallic lead will be found on the bottom of the crucible.
The assay of lead by fire is always attended with a
heavy loss, as lead volatilises readily when strongly heated,
and portions are also liable to be carried off in the slag.
Fire assays of lead ores, when compared with the re-
sults obtained by humid analysis, generally show a loss
varying from 5 to 12 per cent. The fire assay, however,
represents what is produced by smelting lead ores on a
large scale, and it is therefore of great commercial use.
Class A. Take of the finely crushed ore 2 grains, and
mix with 3 grains dry carbonate of soda, O5 grain borax
glass, 0*5 grain powdered charcoal, and 1 grain cyanide
of potassium. In the small crucible (similar to what is
used in the Silver Assay, p. 121) place two small pieces of
wrought iron about the thickness and length of a small
steel pen, and then pour in the assay; cover the assay with
about 4 grains of common salt, but allow the ends of the
iron pieces to project above the assay charge ; put on
the cover of the charcoal furnace, and screw the tightening
pin ; apply a K.F. through the opening made in the fur-
152 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
nace, but apply it at first in a downward direction, so that
the flame does not attack the bottom of the crucible.
After a few minutes' blowing the assay commences to boil,
and the furnace will be found to be at a good red heat.
Do not increase the heat until, by a glance through the
hole in the top of the furnace, the assay is found to be
thoroughly fused ; then increase the heat, and with a pair
of iron pliers extract the pieces of iron one by one whilst
the assay is in a thorough state of fusion. After the iron
has been taken away allow the assay to cool slowly.
When cool, break the crucible between two pieces of
paper on the steel anvil, and clean the lead button and
weigh ; examine the slag with a lens, and if any globules
of lead are found add them to the larger button.
If numerous small globules are found in the slag the
assay should be repeated. This assay only takes about 8
minutes, and if carefully made it will agree closely with
fire assays made on a large scale.
The lead button frequently contains a large amount of
copper. This can be ascertained by dissolving the lead
with boracic acid in a deep bore on charcoal (see Copper
Assay) and deducting the weight of the copper found from
that already considered to be lead.
Lead nearly always contains silver, also gold ; therefore
the button should be cupelled and treated as silver lead
(see Silver Assay). It should also be tested for gold (see
Gold Assay).
Class B. Mix the finely powdered material with 4
grains of carbonate of soda, and 1 grain of argol, and 0*5
grain borax glass
Place the mixture in a small crucible, and after covering
with from 3 to 4 grains of common salt fuse and treat in
a similar manner to Class A.
PART III. BISMUTH. 1 53
BISMUTH.
Bismuth native has a metallic lustre, the streak, and
colour, silver white, with a reddish hue. It tarnishes
readily. It has a hardness of 22*5 and specific gravity
= 9-72.
Native bismuth occurs in veins in gneiss and other
crystalline rocks and in clay slate accompanying various
ores of silver, cobalt, lead, and zinc.
The principal ores of bismuth are
Sulphide', contains bismuth 81*3 per cent., sulphur
18*7 per cent.
Bismuth blende : contains oxide of bismuth 58*8 per
cent., and is mixed with silica, arsenic, and small
proportions of copper, iron, and cobalt.
Acicular bismuth : contains from 34 to 37 per cent,
bismuth, combined with sulphur, copper, and lead.
Carbonate of bismuth : contains about 89*75 per cent,
oxide of bismuth, combined with carbon dioxide and water.
Bismuth has also been found combined with tellurium,
and exists in about the following proportions : bismuth
52 per cent., and tellurium 48 per cent.
The carbonates and oxides of bismuth, when mixed with
their gangue, resemble in appearance some lead ores ; and,
as the assay is conducted in a similar manner, it often
happens that until the button is examined for malleability,
the difference is not discovered. Bismuth forms a brittle
and coarsely crystalline button, having a bright fracture,
which will not bear hammering on the anvil without
breaking up into fragments, whilst lead is ductile and
malleable.
The button, if pure, possesses, when fractured, a fine
reddish colour.
If arsenic is present the button appears of a white colour.
154 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
Copper does not alloy with bismuth, but its presence
can be detected by using a magnifying glass. When copper
is present it will be found to be mixed and not alloyed.
Antimony gives the button a dull appearance, and the
crystals are much finer.
Sulphur blackens bismuth.
Lead, when present, does not prevent bismuth from
forming large crystals, but it is detected by the large
crystals being studded all over with fine crystals
Before making a determinative assay it is best to make
a qualitative examination by taking about 1 ^ grain of the
crushed ore or product and roasting at a gentle heat with
powdered charcoal in a similar manner to the copper assay
(see p. 147).
Then mix with 1^ grain soda, 1^ grain carbonate of
potash, Oo grain borax glass, and a very small quantity of
powdered charcoal. Place in the crucible two small pieces of
metallic iron, add the assay charge, and cover with a thin
layer of salt, and fuse according to directions given in the
Lead Assay (p. 151). The difficulty in making the bismuth
assay by this method is to obtain all the small shots of metal
in one globule. It is seldom done, but the button or buttons
which are formed can be separated from the flux and
examined by hammering on the anvil, when the appearance
of the fracture will, as described above, indicate the pre-
sence of other metals.
To collect bismuth in one button an addition of some
other metal is necessary. Pure silver is considered the
best and is generally employed.
The ores and products of bismuth are assayed in the
following way :
Take 1J grain of the finely powdered mineral and
PART III. BISMUTH. 155
roast on a small clay capsule in a similar manner to the
copper assay. The heat required is not so great as that
necessary in roasting copper ores, as bismuth is readily
fusible and sinters if the heat applied is too great.
After roasting, mix the assay with 2 grains of finely pre-
cipitated pure silver, with 1^ grain soda, 1^ grain car-
bonate of potash, 0-5 grain borax glass, a small quantity
of powdered charcoal, and place in the small crucible, in
which two or three small pieces of iron have been pre-
viously placed ; cover with a thin layer of salt and fuse as
before directed. The button obtained consists of an alloy
of silver and bismuth, but it is seldom clean enough to
weigh without further treatment.
The button should be fused for a few moments on
charcoal with a little borax glass. The flame employed
must be a very mild K.F., as bismuth volatilises at a low
temperature. When the surface of the assay becomes
bright, stop blowing, allow it to cool, and then clean the
button by brushing it.
Weigh, and deduct the weight of the silver previously
added from the total found ; the remainder should be
bismuth.
Bismuth ores and products are generally associated
with silver, and to ensure the assay being correct the
author always makes a separate assay for silver by fusing
1 J grain of the mineral (see Silver Assay), and if any
silver is present its weight -is deducted from the button
of bismuth silver found in the bismuth assay.
No fire assay of bismuth ores or products gives analytic-
ally accurate results. The blowpipe assay is made in less
than half an hour, and is sufficiently accurate to guide
the explorer or metallurgist in his practical estimation or
treatment of the ores or products.
156 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
TIN.
Tin in a metallic state is probably only an artificial pro-
duct.
J. A. Phillips states that tin has more than almost any
other metal a characteristic mode of occurrence, being in-
variably found in the older crystalline and metamorphic
rocks. This opinion is confirmed by Dana and others, and
the author has observed the same peculiarity in the dis-
tribution of tin ores.
Metallic tin is a white metal with a lustre closely
approaching that of silver and with a specific gravity of
7*29. It is easily distinguished from any other metal by
the peculiar ' tin odour ' which it gives to the hand or finger
after it has been rubbed for a few moments.
The principal ore of tin is cassiterite, containing 78*62
tin and oxygen 21*38.
Tin has been found combined with sulphides of copper,
iron, and zinc in Cornwall, in stannite, but the tin obtained
was only 26 per cent.
The pure oxides of tin are readily assayed by a gentle
fusion with a reducing flux in a small crucible before the
blowpipe, when a pure metallic button is obtained ; but, as
many tin ores are combined with an excess of silica as
well as some sulphur, arsenic, and tungsten, it is necessary
to subject them to a preparatory treatment before fusing
them in a crucible with a reducing flux.
Assay.
The tin assay is divided into four classes
Class A.
Pure oxides of tin.
Class B.
Tin ores containing silica, also tin slags.
PART III. TIN. 157
Class C.
Tin ores containing arsenic, sulphur, and tungsten.
Class D.
Ores containing under 5 per cent, of tin.
Class A. Weigh out 1J grain of the oxide, and in-
timately mix with 10 grains of cyanide of potassium
and 1 grain of soda. Place the mixture in a crucible in
the bottom of which has been previously placed and
pressed down a small quantity of cyanide of potassium.
Eemove the crucible to the charcoal furnace and fuse
with a gentle heat. The time required to finish the assay
is seldom more than 6 to 7 minutes. The assay can be
watched, and the completion of the fusion ascertained by
looking through the hole in the top of the furnace. When
cold, break the crucible. The button should be of a
silvery white colour. Dissolve the flux in warm water, and
look carefully for any small shots of tin that may be present.
If any are found they should be cleaned and then weighed
with the large button.
The cyanide of potassium used for blowpipe assaying
being pure, soda is added to secure the perfect fusion of
any small quantities of silica or other impurities which
generally accompany tin oxides.
The button of tin obtained should be rolled or hammered
out, and then tested to see if it contains any lead or copper.
The above-described method, if carefully followed,
affords accurate results.
Class B. Silica being injurious to the extraction of
tin by fusion, the ore to be examined should be first
crushed up fine.
Take from 1 to 20 oz. of the crushed ore, according
to its richness, and van carefully in the batea.
Tin oxides have a specific gravity of about 7, and
silica only a specific gravity of about 2 -7 ; therefore
158 ASSAY OF SILVER, GOLD, MERCURY, ETC. PAIIT III.
the operator, by careful washing, can with safety separate
the silica from the tin ore, or tin stone, as it is generally
termed.
Eemove the concentrated ore from the batea to a small
porcelain dish and carefully dry ; then weigh ; after weigh-
ing grind in the agate mortar and thoroughly mix. Then
weigh out 1 ^ grain of the concentrated ore and proceed
to melt, and determine as in Class A.
The percentage of tin in the original sample treated
is ascertained by first noting the quantity weighed out
for vanning, then noting the quantity of concentrated ore
obtained, and then the amount of pure metallic tin ex-
tracted from 1 1 grain of the concentrated ore.
Sometimes the tin ores cannot be washed down closely
without a loss of tin ; in such a case concentrate the ore
as much as possible by washing, then dry and weigh.
Take 1^ grain of the concentrations and boil with
hydrochloric acid in a platinum dish or porcelain capsule
over the spirit lamp. The assay being finely powdered,
the silica is dissolved. Tin oxide is insoluble in hydro-
chloric acid.
The dissolved silica is decanted off; the tin oxide is
washed with a small quantity of water, then dried, and
fused as in Class A.
Class C. The removal of sulphur, arsenic, and tungsten
from tin is necessary before tin can be extracted in a pure
state from its ores by the blowpipe.
Take from 3 to 10 grains, according to the quality, of
the finely powdered ore, and place it in a small flask ; add
a small quantity of nitro-hydrochloric acid (made up of 3
parts of hydrochloric to 1 part of nitric acid). Boil
until the greater part of the mixed acids has evapo-
rated. Allow the flask to cool, add water, settle, and
decant, and so on until the water is free from acid. The
PART III. TIN. 159
insoluble residue consists of tin oxide, tungsten, and a
little silica. Add a small quantity of caustic ammonia
solution to the residue, and allow it to boil in the flask for
about an hour ; then decant and van the residue to remove
the silica.
Dry the tin oxide and proceed to finish the assay accord-
ing to the method adopted in Class A.
Class D. Many ores of tin contain less than 5 per cent,
of metallic tin.
To arrive at a correct assay of such ores it is necessary
to treat a large quantity. Take about 5 Ibs. in weight of
the finely crushed ore and van carefully in the batea, and
afterwards treat according to the directions given in Classes
A, B, and C.
IRON.
Native iron is rare. It has a hardness 4-5 and specific
gravity= 7*3-7*8, with a metallic lustre and an iron-grey
colour, also a streak shining. It is malleable, but has a
hackly fracture and is strongly attracted by the magnet.
Native iron must be considered only as a mineralogical
curiosity, as it has rarely been found. Nearly all inorganic
as well as organic substances that exist in nature con-
tain more or less iron.
The principal ores from which iron is manufactured
are those in which the iron is combined with oxygen and
carbon, as oxides and carbonates.
Sulphides of iron are disseminated all over the globe,
but they are rarely converted into metallic iron. Magnetic
iron ore contains about 72*41 per cent, iron ; the re-
mainder is oxygen. Specular and red hematite ore contain
about 70 per cent, iron and 30 per cent, oxygen.
Brown iron ore, or brown hematite, contains about
59*90 per cent, iron, and the rest consists of oxygen and
water.
160 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
Carbonate of iron, or spathic iron, contains 48'22 per
cent, iron, and the remainder carbon and oxygen.
Menaccanite (ilmenite), a titanic iron ore, varies in its
composition ; it contains about 36 per cent, of iron on
the average.
Franklinite contains about 45*16 per cent, of iron,
and the remainder is made up of zinc, manganese, and
oxygen.
The assay of iron ores scarcely comes under the head
of the blowpipe fire assay, as the most accurate as well as
expeditious method of ascertaining the percentage of
iron in a sample of ore is nearly all done by the humid
process.
The reagents and apparatus required for the iron
quantitative determination are necessary adjuncts to the
blowpipe outfit; therefore, instead of using a tedious
and a very unreliable method of extracting metallic iron
by fire from its ores, the following plan has been adopted,
as it affords correct results.
Assay.
Crush the iron ore in the steel mortar, and then grind
to the finest possible powder in the agate mortar.
Weigh out 1J grain of the finely powdered ore, and
place the same in a small test tube ; add a little hydrochloric
acid. If the assay effervesces the ore is a carbonate, and
the acid must be added little by little to avoid the loss of
a portion of the assay ; but if effervescence does not take
place the acid can be poured over the assay at once. Heat
the assay contained in the test tube over the spirit lamp
until everything is in solution that the hydrochloric acid
will take up. Then add a few drops of nitric acid and
again boil the assay over the spirit lamp.
PART III. IRON. 161
The assay having been thoroughly boiled, is allowed to
cool, and the solution is diluted with distilled water.
If, on dilution, any sediment is found, it must be sepa-
rated by nitration, and the filter must be examined with
great care in regard to colour. If white, the sediment
contains no iron. If red, yellowish, or grey, it contains
undissolved iron, and it must be treated by carefully
drying it on a procelain dish over the lamp. When dry,
mix it with 3 times its volume of soda and an equal
part of borax glass ; wrap the mixture in a soda-paper
cornet, and fuse it on charcoal in a deep bore with an O.F.
until the mass is thoroughly fused and transparent.
When the fused mass is cold, remove it to the steel
mortar and crush. After crushing, boil with HC1 in a small
porcelain dish, and add a few drops of nitric acid before
the boiling is stopped, and heat slightly for a few moments
to allow oxidation to take place. The solution is then
slowly evaporated to dryness over the lamp. A few drops
of HC1 are added to the dry mass, and then some distilled
water, and it is again warmed over the lamp.
After warming filter, and add the filtrate to the first solu-
tion. The residue, collected on the filter, should be silica.
Add a few drops of sulphuric acid to the solution and stir.
If anything like a white precipitate is seen baryta is present,
and the solution must be allowed to settle. The sulphate of
baryta is separated from the iron solution by filtering.
If the iron ores are pure, the troublesome operations of
dissolving the sediment and separating the baryta, &c., are
dispensed with, and the assay is quickly finished. Add
ammonia to the iron solution. Iron and alumina are
both thrown down together by the above alkaline pre-
cipitant. To obtain an oxide of iron sufficiently pure to
weigh, it is always necessary to separate alumina from
the iron oxide.
M
162 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
Alumina is separated from the iron oxides by attack-
ing the moist precipitate with caustic potash ; the latter
dissolves the alumina, leaving the iron oxide.
The assay is now proceeded with by drying the pre-
cipitate of iron oxides and alumina remaining on the filter
paper.
Before the paper becomes quite dry remove the precipi-
tate from the filter paper with a spatula or small knife.
The filter paper should be placed in a porcelain dish
with a little HC1 and washed with a little warm water,
and this solution added to the main precipitate. In a small
beaker or large test tube boil the iron and alumina pre-
cipitate with a strong solution of caustic potash.
Then dilute with water and collect the sesquioxide of
iron on a filter. Warm the filter containing the precipitate,
and when the filter is nearly dry remove the iron oxide
from the filter to a porcelain capsule. Burn the filter
paper by the blowpipe over a porcelain or platinum dish,
and add the ash and what iron oxide it contains to the
main precipitate. Dry the precipitate and apply a good
red heat to the capsule containing it.
The iron oxide is now weighed, and after deducting
the weight of the ash contained in the filter paper the
metallic iron may, according to Plattner, be estimated as
follows:
6 100 parts of the sesquioxide of iron correspond almost
exactly to 70 parts of metallic iron ; so that it may be
conveniently calculated as 70 parts. If the percentage of
raw iron which a dry assay in a charcoal crucible would give
is required, it may be easily, calculated by assuming the
raw iron from the crucible to contain on an average, in
100 parts, 96 parts of iron and 4 parts of carbon.'
The above-described method of assaying iron ores
affords accurate results, and when such a small quantity
PART III. NICKEL. 163
as 1^ grain is operated upon the assay can be completed
in about 30 minutes and a correct report given.
NICKEL.
Nickel ores have generally a pale colour and a
metallic lustre.
The principal ores of nickel are :
Copper nickel (kupfernickel) has a specific gravity of
7*3 to 7*5, and consists of 44 per cent, of nickel and 56
per cent, of arsenic.
White nickel, an arsenical ore, contains from 20 to 30
per cent, of nickel.
Nickel glance is an arsenical ore, but contains sulphur.
It carries from 20 to 38 per cent, of nickel.
Antimonial nickel contains about 29 per cent, of nickel
and no sulphur.
Millerite is a brass-yellow sulphide of nickel, containing
64 per cent, of nickel.
Pentlandite is a double sulphide of iron and nickel,
and contains from 10 to 21 per cent, of nickel.
Assay.
The assay for nickel alone will be confined to the ore
called kupfernickel, and the remaining varieties will be
treated fully under the head of 'Nickel and Cobalt.'
Kupfernickel, when pure, consists of arsenic 55- 93,
nickel 44-07, but it generally contains about 1 per cent,
of foreign matter, such as iron, cobalt, lead, and sulphur.
Take 1 grain of the finely powdered ore and mix
with grain of borax glass, and fuse on charcoal with
the E.F. After the assay is in a state of fusion treat it
with the outer point of the O.F. until the arseniate of
nickel commences to oxidise ; then dip the globule and slag
whilst still hot in water, to separate the slag, which is easily
M 2
164 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
done with the fingers ; then heat the globule in a deep
bore (in charcoal) with a weak K.F., keeping it in fusion
with a bright surface until all excess of arsenic is vola-
tilised. The globule that remains will weigh about 0*71
grain, and is JN"i 4 As, which contains arsenic 38-825 and
nickel 61-175, and the impurities present account for
the loss.
Care must be taken not to use an excess of borax glass,
as sufficient surface would not be exposed for oxidation.
COBALT.
Cobalt ores generally have a tin-white to steel-grey
colour. The principal ores :
Smcdtine has a specific gravity of 6*4 to 7*2, and con-
tains from 3 to 14 per cent, of cobalt, with from 60 to 75
per cent, of arsenic; the remainder is generally nickel and
iron, with sometimes a trace of copper.
Cobaltitd, or glance cobalt, has a specific gravity of 6
to 6-3, and contains about 35*5 per cent, of cobalt, with
sulphur 19-3 and arsenic 45*2. The cobalt is sometimes
largely replaced by iron and sparingly by copper.
Erytkrite (cobalt bloom) has a pinkish purple colour,
resembling that of a peach blossom, and when scratched it
affords a greenish streak. It is composed of about 39 per
cent, of cobalt oxide, of 37 per cent, of arsenic anhydride,
and 22 per cent, of water.
Cobalt sometimes is found in mispickel (arsenic
pyrites).
Assay.
A full description of the assay of the ores of cobalt
will be described under the head of 'Nickel and Cobalt,'
and only one variety of cobalt ore will be treated separately
for cobalt.
PART III. COBALT. 165
Skutterudite contains, when pure, arsenic 79*26 and
cobalt 20-74, with the occasional replacement of about 2
per cent, of the cobalt by some nickel and iron.
Take 1 grain of the crushed ore and mix with 0-5
grain of soda and 0-15 grain of borax glass in a soda-
paper cornet, and treat on charcoal with a K.F. until all
the metallic particles are united in one globule. By this
means the small quantity of iron present is slagged and
the greater part of the arsenic volatilised. If sulphur is
present it unites with the flux, but causes the latter to
become in a great part absorbed in the charcoal.
If the metallic globule be now freed from adhering
slag, and be heated in a deep bore in charcoal with a E.F.,
and kept fluid until no more arsenic volatilises, the globule
left will weigh about 0*33 grain.
The R.F. must be only strong enough to keep the
metal fluid with a bright surface. If too violent a flame
is applied the assay will boil and spurt, causing a mecha-
nical loss.
The globule now consists of cobalt 61' 131, and arsenic
38-869.
NICKEL AND COBALT ASSAYS.
Plattner's method of conducting the above assay is
the one chiefly adopted in this work, but with many
modifications.
As cobalt and nickel cannot be separated from their
compounds in the metallic state by fusion, like silver,
gold, lead, &c., they are separated by combining them
with arsenic.
The mixed combination of nickel, cobalt, and arsenic
is weighed ; the arsenide of cobalt is then slagged off,
leaving an arsenide of nickel, which can be weighed as
such, and the amount of metallic nickel calculated from
166 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
it. The percentage of cobalt is estimated from the differ-
ence in weight between the mixed arsenides and that of
the arsenide of nickel found. The assay is not only easy
but accurate. The assay has been divided into two classes,
called A and B.
Class A.
Consists of all nickel and cobalt ores and products which are
not combined with arsenic.
Class B.
Consists of all nickel and cobalt ores and products which are
in combination with arsenic.
Class A (a). If nickel and cobalt compounds are not
in the state of arsenides they require to be made so and
then fused to form a button of metallic arsenides before
they can be estimated quantitatively by the blowpipe ;
therefore Class A treats of the arsenides solely.
Take H grain of the ore or product, and if any sul-
phides are present roast according to directions given in
Copper Assay (p. 147). Finish the roasting (when all
odour has ceased to be evolved) by an addition of 1 grain
of carbonate of ammonia, which must be previously tritu-
rated with the assay in the agate mortar.
If sulphur is absent the roasting is dispensed with.
Take the oxidised assay and mix it with 1 to 2 grains
of metallic arsenic in a small clay crucible; place the
crucible in the charcoal furnace on an iron wire ring,
and fuse at a mild heat. It is generally advisable
to cover the crucible with a clay capsule. This assay
should be conducted outside, as the arsenical fumes
are poisonous in a room. The contents of the crucible
are carefully detached, and are then treated according to
'Class B.
If the arsenicising must be done in the room, take 0*75
PART III. NICKEL AND COBALT ASSAYS. 167
grain of the nickel and cobalt oxides and mix with 1*5
grain powdered metallic arsenic, and wrap in a small soda-
paper cornet. Place the assay in the bottom of a small
tube closed at one end.
Place in the mouth of the tube a small roll of dry
filter paper, to absorb the moisture evolved from the
charred soda paper. Heat the assay gradually over the
spirit lamp to redness.
Turn the tube every now and then, to prevent the
charred paper adhering to the sides of the tube. Con-
tinue the heat until no more sublimate of arsenic is found
on the inside of the tube.
Cut off the lower portion of the tube (by using a file)
containing the assay, and remove carefully.
The assay is now treated as Class B. If the oxide
consists chiefly of protoxide of nickel and oxides of cobalt
in which the former prevails, the resulting arsenides can
easily be melted to one button during the fusion in the
crucible ; if, however, oxide of cobalt prevails, the result-
ing arsenides melt with difficulty, and about 0-25 grain
of iron filings must be added, so as to form arsenide of
iron, which produces a fusible combination with the
arsenide of cobalt in the subsequent fusion.
Class B (a) consists of nickel and cobalt, combined
with arsenic and some iron.
Take 1^ grain of the finely powdered mineral, and
mix on the agate mortar with 0*8 grain soda, 0*20 grain
borax glass. Place a soda-paper cornet in a deep bore in
charcoal, and fuse with a moderate E.F. until the flux has
become a slag and the metallic particles have united to a
button. Cool the button in water to remove the slag*
Fuse the button on a cavity in charcoal with a mild E.F.
until the button shows a bright surface and assumes a
rotary motion. The iron has then been slagged off. Con-
168 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
tinue to keep the button in fusion until all fumes of
arsenic have ceased to be evolved.
Allow the button to cool, and weigh ; the weight gives
the sum of (CoNi) 4 As.
The amount of metal in the weighed arsenides is as
follows :
Co 4 As . . 61 '5 percent, cobalt.
Ni 4 As . . 607 nickel.
Sometimes it is difficult to slag off the last traces of
the iron ; in such a case add a little borax glass, and fuse
until the button shows a perfectly bright surface.
The button having been weighed, the cobalt is next
slagged off by fusing with a moderate E.F. in a cavity on
charcoal, a small quantity of borax glass having been pre-
viously added.
Cobalt separates slowly, and until it is all gone the
solidified button is always covered with a black crust of
oxide. The brightening of the button continues on add-
ing fresh borax so long as the arsenide of cobalt is present ;
but when all of the cobalt is separated, and the arsenide
of nickel begins to oxidise, a film of basic arseniate of
nickel forms, which moves slowly about the surface.
If the blast is stopped as soon as the phenomenon
above described can be distinctly perceived, and a part of
the glass immediately pinched out and slowly raised, re-
maining still connected with the main portion, it appears
generally rather violet than blue against the daylight,
provided it is not too strongly coloured with cobalt.
If all the cobalt had been separated the glass would
only appear pale brown. On the surface of the remain-
ing arsenide of nickel beside the purple glass is seen an
apple-green film of basic arseniate of nickel, which indicates
that only Ni 4 As remains.
PART III. NICKEL AND COBALT ASSAYS. 169
The Co 4 As is completely slagged off, while the Ni 4 As
retains none of the arsenic from it, and therefore both
metals can be quantitatively determined in the compounds.
If proper care is taken in making the above assay the
loss of nickel (even if a large film is observed on the sur-
face of the assay) is so small that it can scarcely be de-
termined on the fine assay balance.
Class B (6) consists of ores and products in which
nickel, cobalt, copper, and iron are combined with a small
quantity of arsenic.
Take 1 J grain for assay and treat in a similar manner
to Class A. After the cobalt has been slagged off any
copper that is present will be found combined with the
nickel compound as
Ni 4 As and Co 6 As.
If the amount of copper present exceeds that of nickel
it must be treated by the humid method. After weigh-
ing the button of nickel, copper, and arsenic, add 1 grain
of pure gold, and fuse with a moderate heat on a cavity
on charcoal with a small quantity of salt of phosphorus.
Allow air to get access to the button. Arsenide of
nickel soon dissolves in the glass, making the glass a pure
yellow colour.
When the salt has become saturated, cool the button
in water, remove the slag, and again fuse with a fresh
portion of the salt, and treat until its surface ceases to be
covered with a film of oxide and begins to show a bluish
green colour. Cool the button in water, and then separate
the last portions of arsenide of nickel by fusing as usual
with a little borax on charcoal.
If the cupriferous gold button shows a clean, metallic,
lustrous surface, and does not crack wh^n beaten out cold,
170 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
it is weighed, and the copper determined from the in-
crease in weight.
Arsenide of copper has the following composition :
Cu 6 As . . 71 '7 per cent, copper.
28-3 arsenic.
Class B (c) consists of arsenides of nickel, cobalt, iron,
copper, also brass and products containing lead, bismuth,
zinc, sulphur, and earthy matters.
1 grain of the finely powdered mineral is roasted
according to directions given in Class A, and also after-
wards arsenicised as there directed.
Mix the assay with 3 grains soda, 2 grains potash, and
0*5 grain borax glass. Add 1 grain pure silver. Place
the mixture in the clay crucible, in which a small piece of
iron has been added, cover with a thin layer of salt, and,
after covering with a clay cup, fuse as directed in the
Lead Assay (p. 151).
The heat must be sharp towards the end, to collect the
arsenide in one button.
In five or six minutes the arsenides collect in a round
button at the bottom, and the earthy matters and oxides,
which do not separate in the metallic state, are completely
slagged off. The iron passes into the metallic arsenides^
and the lead or bismuth passes into an alloy with the
silver, which unites with the arsenides in one button, but
which can be easily mechanically separated. The
quantity of lead or bismuth present can be estimated by
first weighing the alloy and then cupelling it, when the
loss will be either lead or bismuth. The presence of
either should be looked for by the qualitative test before-
hand.
If any zinc or antimony is present it is volatilised
when the arsenide of iron is removed with borax.
PART III. NICKEL AND COBALT ASSAYS. 171
The assay is now finished according to instructions
given in Class B (6) (p. 169).
Class B (d). Some ores are so poor in nickel and
cobalt that they require a collecting agent, which can
afterwards be easily slagged off. Take 1^ grain of the
powdered ore ; mix with 0-40 grain of arsenide of iron
(made by fusing iron filings with metallic arsenic in a
clay crucible), 2 grains potash, 3 grains soda, and 0'5 grain
borax glass ; cover with a thin layer of salt, and finish as
directed in c and d, Class B.
Alloys of copper and nickel in which copper pre-
dominates cannot be estimated by the fire assay, but have
to be determined by the wet way. Alloys of nickel, cobalt,
and antimony cannot be determined by the blowpipe.
COAL.
Coal (or rather mineral coal) occurs in beds inter-
stratified with shales, sandstones, and conglomerates, and
sometimes limestones, forming distinct layers, which
vary from a fraction of an inch to 30 feet or more in
thickness.
Its hardness varies from 0'5 to 2*5, and its specific
gravity from 1 to 1'80. Lustre dull to brilliant, and either
earthy, resinous, or submetallic. Colour black, greyish
black, brownish black, and occasionally iridescent ; also
sometimes dark brown and opaque. Fracture conchoidal
to uneven.
Brittle ; rarely somewhat sectile. Without, taste, ex-
cept from impurities present.
The origin of coal is mainly vegetable, though animal
life has contributed somewhat to the result.
Coal beds were once beds of vegetation, which have
been buried during different geological ages. The car-
172 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
boniferous period furnishes the greatest and best supply,
but it is also found in beds of the Triassic, Oolitic, Cre-
taceous, and Tertiary eras.
The principal varieties of coal are as follows :
Anthracite^or Hard Coal. Hardness 2-2-5 ; spec. grav.
= 1*32 1*70. Contains volatile matter after drying, 3 to
6 per cent. Contains carbon, 80 to 95 per cent. It has
a high lustre and burns without flame, as it contains
little or no bitumen. It is totally devoid of impressions
of plants, and is, geologically speaking, the oldest of all
kinds of fossil charcoal and is regarded as the last stage
of carbonisation. It yields from 1 to 7 per cent, of ash,
but 3 per cent, may be called the average.
Brown Coal,or Lignite, contains from 57 to 70 per cent.
of carbon, and represents the first stage of carbonisation,
and is a coal of comparatively recent formation. It is
composed of fossil plants more or less mineralised, and
when burnt it evolves much smoke and affords a dull
flame, and generally yields a large quantity of ash. It
contains from 2 to 19 per cent, ash and gives from 30
to 50 per cent. coke.
Caking Coal. A bituminous coal which softens and
becomes pasty in the fire, and after the heat has been
continued for a time the volatile ingredients are driven
off, and a greyish black fretted mass is left. The
coke obtained from this coal varies from 50 to 85 per
cent.
Non-Caking Coal resembles the above in its external
character, but burns freely without softening or showing
any appearance of incipient fusion.
Cannel Coal. - A bituminous coal which generally
cakes. It is compact, with little or no lustre, and has
a dull black or greyish black colour. On distillation it
affords, after drying, 40 to 66 per cent, of volatile matter.
PART III. COAL. 173
When held in the flame of a candle it easily ignites,
burning with a steady bright flame. It is used ex-
tensively for the manufacture of illuminating gas, of which
it affords a better quality than any other species of coal.
Coal can be examined and its commercial properties
determined by the blowpipe with great accuracy.
Assay.
The assay is divided into five heads :
1st. The moisture determination.
Select from the mass of coal to be examined a few
lumps representing as nearly as possible the average
quality. Crush them up in the agate mortar into small
pieces about the size of a mustard seed.
Weigh out 5 grains, place in a small porcelain dish,
and dry at a gentle heat over the spirit lamp. Hard
coals sometimes fly when heated, so it is best to cover the
dish with a watch glass whilst heating. After about 5
minutes remove the assay and weigh; then repeat the
heating and again weigh. As soon as the weights agree
the assay is ready to be converted into coke. Plattner
states that the percentage of moisture is lowest in anthra-
cite; in bituminous coals it is usually 3 to 4 per cent.,
seldom 6 to 7, and reaches its maximum in lignite and
brown coals, which contain 20 per cent, and sometimes
more.
2nd. Determination of the coke production.
Take the dried coal and remove to a clay or platinum
crucible, and cover with a small roasting clay dish or plati-
num cup. Place the crucible on a triangle of platinum wire
on the blowpipe stand under the flame, using alcohol, and
cover it with a small sheet-iron funnel (the same that is
used in roasting copper ores). The heat is continued until
all the volatile gas has escaped, when the assay generally
174 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
will appear to possess a fused porous appearance, and to
have a metallic lustre.
The coke so made is now removed and weighed. It
should be weighed quickly, as coke absorbs moisture from
the air rapidly. The coking takes about 10 minutes, and
the crucible should not be allowed to get beyond a red
heat.
3rd. The estimation of the amount of ash.
After the percentage of coke has been determined
remove the assay to a small clay or platinum capsule, and,
without using a cover, again heat over the lamp this time
to a bright red colour until all the carbon has been con-
sumed. The operation is much facilitated by occasionally
stirring the assay with a piece of platinum wire, also by
applying the blowpipe flame to the bottom of the cup
when the assay is nearly finished.
If alcohol cannot be obtained the assay for coke and
ash can be conducted in the charcoal furnace by using
the blowpipe flame, as in the copper assay, and if the ash
amounts to more than 5 per cent, the value of the coal is
much diminished. If the ash presents a brown, red, or
grey colour, sesquioxide of iron has been formed by the
oxidation of the pyrites in the coal.
4th. Determination of the absolute heating power by
Berthier's process.
Take an average sample of the coal and crush it up to
the finest powder. Weigh out 0'3 grain of the coal dust
and mix it with 12 grains of oxy chloride of lead, and after
placing the mixture in the crucible cover it with an ad-
ditional 12 grains of oxy chloride of lead.
Oxychloride of lead fuses more readily than litharge;
therefore, owing to the large quantity of material which
must be brought into a state of fusion in this determina-
tion, it is employed instead of litharge.
PART III. COAL. 175
The assay is next covered with a little powdered glass,
also with a few spoonfuls of borax glass. A clay cup is
placed over the crucible, and the assay is then fused in
the charcoal furnace in a similar manner to the silver
assay when litharge is used (see p. 122).
About 7 or 8 minutes suffices to melt the assay, and the
lead button produced by the carbon in the coal acting on the
lead oxychloride will be found lying upon the bottom of the
.crucible when the assay is cool and the crucible is broken.
The weight of the button, when cleaned from the
slag, divided by 20, gives the quantity of lead that 1
part of the fuel under examination can reduce ; and since
1 part of carbon reduces 34 parts of lead, the heating
power of the fuel may be easily ascertained. The amount
of lead reduced by 1 part of coal varies with the different
pit coals between 21 and 32 parts, with the lignites
between 16 and 25 parts. In making this assay the heat
must be applied at first very gradually, and afterwards
increased to a bright redness.
Dr. Ure's experiments, published in the ' Supplement
to the Dictionary of Arts, Mines, and Manufactures,' have
appeared to be unsatisfactory in regard to the accuracy of
Berthier's method. Mitchell, however, has found the
method correct, and the author has found it equally so.
The lead oxychloride should always be pure.
5th. "Estimation of sulphur in a sample of coal.
Sulphur generally exists in coal as a sulphide of iron,
and as the presence of more than 2 per cent, of sulphur
depreciates the market value of coal, owing to its destroy-
ing the iron boilers and grates under and over which the
coal is consumed, it is always an important part of the
examination of coal to ascertain the quantity present.
Mitchell, in his ' Manual of Practical Assaying,' re-
commends the following process :
176 ASSAY OF SILVER, GOLD, MERCURY, ETC. PART III.
'Take 1 part of the finely pulverised coal and mix with
7 to 8 parts of nitre, and 1 6 parts of common salt, and 4
parts of carbonate of potash, all of which must be per-
fectly pure. The mixture is then placed in a platinum
crucible and gently heated at a certain temperature ; the
whole ignites and burns quietly. The heat is then in-
creased until the mass is fused ; the operation is finished
when the mass is white. It must, when cold, be dissolved
in water, the solution slightly acidulated by means of
hydrochloric acid, and chloride of barium added to it as
long as a white precipitate forms. This precipitate is
sulphate of baryta, which must be collected on a filter,
washed, dried, ignited, the filter burnt away, and the
remaining sulphate of baryta weighed : every 116 parts
of it indicate 16 of sulphur.'
The above-described methods of examining coal are
all that are required for commercial purposes. The assay
may be carried on still further by estimating the iron
oxide contained in the ash, according to the instructions
given in the quantitative iron assay. The ash can also be
examined qualitatively for silica, lime, soda, and potash
(see ' Qualitative Determination ').
PART IV.
TABLES OF ENGLISH AND AMERICAN VALUES OF GOLD
ACCORDING TO ITS FINENESS;
ALSO THE
VALUE OF GOLD COINS IN THE UNITED STATES
OF AMERICA.
PART IV.
ENGLISH VALUE OF GOLD.
179
Table of the English Mint Value of Gold per Ounce Troy,
at Different Degrees of Fineness.
Fineness of
Gold
Value per Ounce
Fineness of
Gold
Value per Ounce
x. d.
s. d.
1000
4 4 11-4545
962
4 1 8-7152
999
4 4 10-4350
961
4 1 7-6958
998
4 4 9-4156
960
4 1 6-6763
997
4 4 8-3961
959
4 1 5-6569
996
4 4 7-3767
958
4 1 46374
995
4 4 6-3572
957
4 1 3-6179
994
4 4 5-3378
956
4 1 2-5985
993
4 4 4-3183
955
4 1 1-5790
992
4 4 3-2989
954
4 1 05596
991
4 4 2-2793
953
4 11-5401
990
4 4 1-2600
952
4 10 5207
989
4 4 02405
951
4 9-5012
988
4 3 11-2210
950
4 8-4818
987
4 3 10 2016
949
4 7-4623
986
4 3 9-1821
948
4 6-4429
985
4 3 81627
947
4 5-4234
984
4 3 7-1432
946
4 4-4039
983
4 3 6-1238
945
4 3-3835
982
4 3 5-1043
944
4 2-3650
981
4 3 4-0849
943
4 13456
980
4 3 3-0654
942
4 03261
979
4 3 20459
941
3 19 11-3067
978
4 3 1-0265
940
3 19 10-2872
977
4 3 0-0070
939
3 19 9-2678
976
4 2 10 9876
938
3 19 8 2483
975
4 2 99681
937
3 19 7-2289
974
4 2 8-9487
936
3 19 6-2094
973
4 2 7-9292
935
3 19 5-1899
972
4 2 69098
934
3 19 4-1705
971
4 2 5-8903
933
3 19 3-1510
970
4 2 4-8709
932
3 19 2-1316
969
4 2 3-8504
931
3 19 1 1121
968
4 2 28319
930
3 19 00927
967
4 2 1-8125
929
3 18 11 0732
966
4 2 07930
928
3 18 10-0538
965
4 1 11-7736
927
3 18 9-0343
964
4 1 10 7541
926
3 18 8-0149
963
4 1 9-7347
925
3 18 6-9954
N 2
180 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV.
Table of the English Mint Value of Gold continued.
Fineness of
Gold
Value per Ounce
Fineness of
Gold
Value per Ounce
j. d.
s. d.
924
3 18 5 9759
882
3 14 11-1589
923
3 18 4-9565
881
3 14 10-1394
922
3 18 3 9370
880
3 14 91199
921
3 18 2-9176
879
3 14 8-1005
920
3 18 1-8981
878
3 14 7-0810
9] 9
3 18 0-8787
877
3 14 6-0616
918
3 17 11 8592
876
3 14 5-0421
917
3 17 10-8398
875
3 14 4-0227
916
3 17 9-8203
874
3 14 3-0032
915
3 17 8-8009
873
3 14 1 9838
914
3 17 7 7814
872
3 14 0-9643
913
3 17 6-7619
871
3 13 11-9449
912
3 17 5 7425
870
3 13 109254
911
3 17 4-7230
869
3 13 99059
910
3 17 3 7036
868
3 13 88865
909
3 17 2 6841
867
3 13 7-8670
9u8
3 17 1 6647
866
3 13 6-8476
907
3 17 0-6452
865
3 13 5-8281
906
3 16 11-6258
864
3 13 4-8087
905
3 16 10-6063
863
3 13 37892
904
3 16 9-5869
862
3 13 2 7698
903
3 16 8-5674
861
3 13 1-7503
902
3 16 7-5479
860
3 13 0-7309
901
3 16 6-5285
859
3 12 11-7114
900
3 16 5-5090
858
3 12 10-6919
899
3 16 4 4896
857
3 12 9-6725
898
3 16 3-4701
856
3 12 8-6530
897
3 16 24507
855
3 12 7*6336
896
3 16 1-4312
854
3 12 6-6141
895
3 16 0-4118
853
3 12 5-5947
894
3 15 11-3923
852
3 12 4 5752
893
3 15 10 3729
851
3 12 3-5558
892
3 15 9-3534
850
3 12 2-5363
891
3 15 8-3339
849
3 12 1-5169
890
3 15 7-3145
848
3 12 0-4974
889
3 15 6 2950
847
3 11 11-4779
888
3 15 5-2756
846
3 11 10-4585
887
3 15 42561
845
3 11 9-4390
886
3 .15 3-2367
844
3 11 8-4196
885
3 15 2-2172
843
3 11 7-4001
884
3 15 1-1978
842
3 11 6 3807
883
3 15 0-1783
841
3 11 5-3612
PART IV.
ENGLISH VALUE OF GOLD.
181
Table of the English Mint Value of Gold continued.
Fineness of
Gold
Value per Ounce
Fineness of
Gold
Value per Ounce
& s. d.
s. d.
840
3 11 4-3418
798
3 7 9-5247
839
3 11 3-3223
797
3 7 8-5052
838
3 11 2-3029
796
3 7 7-4858
837
3 11 1-3834
795
3 7 6-4663
836
3 11 0-2639
794
3 7 5-4469
835
3 10 11 2445
793
3 7 4-4274
834
3 10 10-2250
792
3 7 3-4979
833
3 10 9-2056
791
3 7 2-3885
832
3 10 8-1861
790
3 7 1-3690
831
3 10 7-1667
789
3 7 0-3496
830
3 10 6-1472
788
3 6 11-3301
829
3 10 5 1278
787
3 6 10-3107
828
3 10 4-1083
786
3 6 92912
827
3 10 3-0889
785
3 6 8-2718
826
3 10 2 0694
784
3 6 7-2523
825
3 10 1-0499
783
3 6 6-2329
824
3 10 0-0305
782
3 6 5-2134
823
3 9 11-0110
781
3 6 41939
822
3 9 9-9916
780
3 6 31745
821
3 9 8-9721
779
3 6 2-1550
820
3 9 7-9527
778
3 6 1-1356
819
396 9332
777
3 6 0-1161
818
3 9 5-9138
776
3 5 11-0967
817
3 9 4-8943
775
3 5 100772
816
3 9 3-8749
774
3 5 9-0578
815
3 9 2-8554
773
3 5 8-0383
814
3 9 1-8359
772
3 5 7-0189
813
3 9 0-8165
771
3 5 5-9994
812
3 8 11 7970
770
3 5 4-9799
811
3 8 10-7776
769
3 5 3-9605
810
3 8 97581
768
3 5 2-9410
809
3 8 8-7387
767
3 5 1-9216
808
3 8 7-7192
766
3 5 09021
807
3 8 66998
765
3 4 11-8827
806
3 8 5-6803
764
3 4 10-8632
805
3 8 46609
763
3 4 9-8438
804
3 8 3-6414
762
3 4 8-8243
803
3 8 2-6219
761
3 4 7-8049
802
3 8 1-6025
760
3 4 6-7854
801
3 8 0-5830
759
3 4 57659
800
3 7 11-5636
758
3 4 47465
799
3 7 10-5441
757
3 4 3-7270
182 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV.
Table of tlis English Mint Value of Gold continued.
Fineness of
Gold
Value per Ounce
Fineness of
Gold
Value per Ounce
5. d.
& s. d.
756
3 4 2-7076
714
3 7-8905
755
3 4 1-6881
713
3 6-8710
754"
3 4 0-6687
712
3 5-8516
753
3 3 11-6492
711
3 48321
752
3 3 10-6298
710
3 3-8127
751
3 3 96103
709
3 2-7932
750
3 3 8-5909
708
3 1-7738
749
3 3 7-5714
707
3 0-7543
748
3 3 6-5519
706
2 19 11-7349
747
3 3 55325
705
2 19 10-7154
746
3 3 4-5130
704
2 19 9-6959
745
3 3 3-4936
703
2 19 86765
744
3 3 24741
702
2 19 7-6570
743
3 3 1-4547
701
2 19 6-6376
742
3 3 0-4352
700
2 19 5-6181
741
3 2 11-4158
699
2 19 4-5987
740
3 2 10-3963
698
2 19 3-5792
739
3 2 9-3769
697
2 19 2-5598
738
3 2 8-3574
696
2 19 1-5403
737
3 2 7-3379
695
2 19 05209
736
3 2 6-3185
694
2 18 11-5014
735
3 2 5-2990
693
2 18 10-4820
734
3 2 42796
692
2 18 9-4625
733
3 2 3-2601 691
2 18 84430
732
3 2 2-2407 690
2 18 7-4236
731
3 2 1-2212
689
2 18 6-4041
730
3 2 0-2018 688
2 18 5 3847
729
3 1 111823 687
2 18 4-3652
728
3 1 10-1629
686
2 18 3-3458
727
3 1 91434
685
2 18 2-3263
726
3 1 8-1239
684
2 18 1-3069
725
3 1 7-1045
683
2 18 0-2874
724
3 1 6-0850
682
2 17 11 2680
723
3 1 5-0656
681
2 17 10 2485
722
3 1 4-0461
680
2 17 9-2290
721
3 1 3-0267
679
2 17 8-2096
720
312 0072
678
2 17 7-1901
719
3 1 0-9878
677
2 17 6-1707
718
3 11-9683
676
2 17 5-1512
717
3 10-9489
675
2 17 4-1318
716
3 9-9294
674
2 17 3-1123
715
3 8-9099
673
2 17 2-0929
PART IV.
ENGLISH VALUE OF GOLD.
183
Table of the English Mint Value of Gold continued.
Fineness of
Gold
Value per Ounce
Fineness of
Gold
Value per Ounce
& s. cl.
s. d.
672
2 17 1-0734
630
2 13 6-2563
671
2 17 00540
629
2 13 5-2369
670
2 16 11-0345
628
2 13 4-2174
669
2 16 100151
627
2 13 3-1979
668
2 16 8-9956
626
2 13 2-1785
667
2 16 7-9761
625
2 13 1-1590
666
2 16 6 9567
624
2 13 0-1396
665
2 16 5-9372
623
2 12 11-1201
664
2 16 4-9178
622
2 12 10 1007
663
2 16 3-8983
621
2 12 90812
662
2 16 2-8789
620
2 12 8-0618
661
2 16 1-8594
619
2 12 7 0423
660
2 16 0-8399
618
2 12 6-0229
659
2 15 11-8205
617
2 12 5 0034
658
2 15 10-8010
616
2 12 3-9839
657
2 15 9-7816
615
2 12 2-9645
656
2 15 8 762]
614
2 12 1-9451
655
2 15 7-7427
613
2 12 9256
654
2 15 6-7232
612
2 11 11-9061
653
2 15 5-7038
611
2 11 10-8867
652
2 15 4-6843
610
2 11 9-8672
651
2 15 3 6649
609
2 11 8-8478
650
2 15 2-6454
608
2 11 7-8283
649
2 15 1-6259
607
2 11 6 8089
648
2 15 6065
606
2 11 5-7894
647
2 14 11 5870
605
2 11 4-7699
646
2 14 10-5676
604
2 11 3 7505
645
2 14 9-5481
603
2 11 2-7311
644
2 14 8-5287
602
2 11 1-7116
643
2 14 7-5092
601
2 11 0-6921
642
2 14 6-4898
600
2 10 11-6727
641
2 14 5-4703
599
2 10 10-6532
640
2 14 4-4509
598
2 10 9-6338
639
2 14 3-4314
597
2 10 8-6143
638
2 14 2-4120
596
2 10 7-5949
637
2 14 1-3925
595
2 10 6-5754
636
2 14 0-3730
594
2 10 5 5559
635
2 13 11-3536
593
2 10 4-5365
634
2 13 10-3341
592
2 10 3-5170
633
2 13 9-3147
591
2 10 2-4976
632
2 13 8-2952
590
2 10 1-4781
631
2 13 7-2758
589
2 10 0-4587
184 ENGLISH AND AMEEICAN VALUES OF GOLD. PART IV.
Table of the English Mint Value of Gold continued.
Fineness of
Gold
Value per Otmce
Fineness of
Gold
Value per Ounce
.?. (1.
s. d.
588
2 9 114392
546
2 6 4-6221
587
2 9 10-4198
545
2 6 36027
586
2 9 9-4003
544
2 6 2-5832
585
2 9 8-3809
543
2 6 1-5638
584
2 9 73614
542
2 6 05443
583
2 9 6-3419
541
2 5 11-5249
582
2 9 5-3225
540
2 5 10 5054
581
2 9 4-3030
539
2 5 9-4859
580
2 9 3-2836
538
2 5 8-4665
579
2 9 2-2641
537
2 5 7-4470
578
2 9 12447
536
2 5 6-4276
577
2 9 0-2252
535
2 5 5-4081
576
2 8 11-2058
534
2 5 4-3887
575
2 8 10-1863
533
2 5 33692
574
2 8 9-1669
532
2 5 2-3498
573
2 8 8-1474
531
2 5 13303
572
2 8 7-1279
530
2 5 0-3109
571
2 8 6-1085
529
2 4 11-2914
570
2 8 5-0890
528
2 4 10-2719
569
2 8 4-0696
527
2 4 9-2525
568
2 8 3-0501
526
2 4 8-2330
567
2 8 2-0307
525
2 4 7-2136
566
2 8 1-0112
524
2 4 6-1941
565
2 7 11-9918
523
2 4 5-1747
564
2 7 109723
522
2 4 4-1552
563
2 7 9-9529
521
2 4 3-1358
562
2 7 8-9334
520
2 4 21163
561
2 7 7-9140
519
2 4 1-0969
560
276 8945
518
2 4 0-0774
559
2 7 5-8751
517
2 3 11-0579
558
2 7 4-8556
516
2 3 10-0385
557
2 7 3-8361
515
2 3 9-0190
556
2 7 2-8167
514
2 3 7-9996
555
2 7 1-7972
513
2 3 6-9801
554
2 7 0-7778
512
2 3 5-9607
553
2 6 11-7583
511
2 3 4-9412
552
2 6 10-7389
510
2 3 3-9218
551
2 6 97194
509
2 3 2-9023
550
2 6 8-6999
508
2 3 1-8829
549
2 6 7-6805
507
2 3 0-8634
548
2 6 6-6611
506
2 2 11-8439
547
2 6 5-6416
505
2 2 10-8245
i
FART IV.
ENGLISH VALUE OF GOLD.
185
Table of tlie English Mint Value of Gold continued.
Fineness of
Gold
Value per Ounce
Fineness of
Gold
Value per Ounce
.?. d.
s. d.
504
2 2 9-8051
462
1 19 2-9879
503
2 2 8-7856
461
1 19 1-9685
502
2 2 77661
460
1 19 0-9490
501
2 2 6-7467
459
1 18 11-9296
500
2 2 5-7272
458
1 18 10-9101
499
2 2 4-7078
457
1 18 9-8907
498
2 2 3-6883
456
1 18 8-8712
497
2 2 2-6689
455
1 18 7-8518
496
2 2 1-6494
454
1 18 6-8323
495
2 2 0-6300
453
1 18 5-8129
494
2 1 11-6105
452
1 18 4-7934
493
2 1 10-5911
451
1 18 3-7739
492
2 1 9-5716
450
1 18 2-7545
491
2 1 8-5521
449
1 18 1-7351
490
2 1 7-5327
448
1 18 0-7156
489
2 1 1-5132
447
1 17 11-6961
488
2 1 5-4938
446
1 17 10-6767
487
2 1 4-4743
445
1 17 9-6572
486
2 1 3-4549
444
1 17 8-6378
485
2 1 2-4354
443
1 17 7-6183
484
2 1 1-4159
442
1 17 6-5989
483
2 1 0-3965
441
1 17 5-5794
482 .
2 11-3770
440
1 17 4-5599
481
2 10-3576
439
1 17 3-5405
480
2 9-3381
438
1 17 2-5211
479
2 8-3187
437
1 17 1-5016
478
2 7-2992
436
1 17 0-4821
477
2 6-2798
435
1 16 11-4627
476
2 5-2603
434
1 16 10-4432
475
2 4-2409
433
1 16 9-4238
474
2 3-2214
432
1 16 8-4043
473
2 2-2020
431
1 16 7-3849
472
2 1-1825
430
1 16 6-3654
471
2 0-1630
429
1 16 5-3459
470
1 19 11-1436
428
1 16 4-3265
469
1 19 10-1241
427
1 16 3-3070
468
1 19 9-1047
426
1 16 2-2876
467
1 19 8-0852
425
1 16 1-2681
466
1 19 7-0658
424
1 16 0-2487
465
1 19 6-0463
423
1 15 11-2292
464
1 19 5-0269
422
1 15 10-2098
463
1 19 4-0074
421
1 15 9-1903
186 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV.
Table of tlw English Mint Value of Gold continued.
Fineness of
Gold
Value per Ounce
Fineness of
Gold
Value per Ounce
*. d.
.?. d.
420
1 15 8-1709
378
1 12 1-3538
419
1 15 7-1514
377
1 12 0-3343
418
1 15 6-1319
376
1 11 11-3142
417
1 15 5-1125
375
1 11 10-2954
416
1 15 4-0930
374
1 11 9-2759
415
1 15 3-0736
373
1 11 8-2565
414
1 15 2-0541
372
1 11 7-2370
413
1 15 1-0347
371
1 11 6-2176
412
1 15 0-0152
370
1 11 5-1981
411
1 14 10-9958
369
1 11 4-1787
410
1 14 9-9763
368
1 11 3-1592
409
1 14 8-9569
367
1 11 2-1398
408
1 14 7-9374
366
1 11 1-1203
407
1 14 6-9179
365
1 11 0-1009
406
1 14 5-8985
364
1 10 11-0814
405
1 14 4-8790
363
1 10 10-0620
404
1 14 3-8596
362
1 10 9-0425
403
1 14 2-8401
361
1 10 8-0230
402
1 14 1-8207
360
1 10 7-0036
401
1 14 0-8012
359
1 10 5-9841
400
1 13 11-7818
358
1 10 4-9647
399
1 13 10-7623
357
1 10 3-9452
398
1 13 9-7429
356
1 10 2-9258
397
1 13 8-7234
355
1 10 1-9063
396
1 13 7-7039
354
1 10 0-8869
395
1 13 6-6845
353
1 9 11-8674
394
1 13 5-6651
352
1 9 10-8479
393
1 13 4-6456
351
1 9 9-8285
392
1 13 3-6261
350
1 9 8-8090
391
1 13 2-6067
349
1 9 7-7896
390
1 13 1-5872
348
1 9 6-7701
389
1 13 0-5678
347
1 9 5-7507
388
1 12 11-5483
346
1 9 4-7312
387
1 12 10-5289
345
1 9 3-7118
386
1 12 9-5094
344
1 9 2-6923
385
1 12 8-4899
343
1 9 1-6729
384
1 12 7-4705
342
1 9 0-6534
383
1 12 6-4511
341
1 8 11-6339
382
1 12 5-4316
340
1 8 10-6145
381
1 12 4-4121
339
1 8 9-5951
380
1 12 3-3927
338
1 8 8-5756
379
1 12 2-3732
3S7
1 8 7-5561
PART IV.
ENGLISH VALUE OF GOLD.
187
Table of the English Mint Value of Gold continued.
Fine-ness of
Gold
Value per Ounce
Fineness of
Gold
Value per Ounce
& s. d.
s. d.
336
1 8 6-5367
294
1 4 11-7196
335
1 8 5-5172
293
1 4 10-7011
334
1 8 4-4978
292
1 4 9-6807
333
1 8 3-4783
291
1 4 8-6612
332
1 8 2-4589
290
1 4 7-6418
331
1 8 1-4394
289
1 4 6-6223
330
1 8 0-4199
288
1 4 5-6029
329
1 7 11 4005
287
1 4 4-5834
328
1 7 10-3811
286
1 4 3-5639
327
1 7 9-3616
285
1 4 2-5445
326
1 7 83421
284
1 4 1-5251
325
1 7 7-3227
283
1 4 0-5056
324
1 7 6-3032
282
1 3 11-4861
323
1 7 5-2838
281
1 3 10-4667
322
1 7 4-2643
280
1 3 9-4472
321
1 7 32449
279
1 3 8-4278
320
1 7 22254
278
1 3 7-4083
319
1 7 1-2059
277
1 3 6-3889
318
1 7 0-1865
276
1 3 5-3694
317
1 6 11-1670
275
1 3 4-3499
316
1 6 10-1476
274
1 3 3-3305
315
1 6 9-1281
273
1 3 2-3110
314
1 6 8-1087
272
1 3 1-2916
313
1 6 7-0892
271 "
1 3 0-2721
312
1 6 6-0698
270
1 2 11-2527
311
1 6 5-0503
269
1 2 10-2332
310
1 6 4-0309
268
1 2 9-2138
309
1 6 3-0114
267
1 2 8-1943
308
1 6 1-9919
266
1 2 7-1749
307
1 6 0-9725
265
1 2 6-1554
306
1 5 11-9530
264
1 2 5-1351
305
1 5 10-9336
263
1 2 4-1165
304
1 5 9-9141
262
1 2 3-0970
303
1 5 8-8947
261
1 2 2-0776
302
1 5 7-8752
260
1 2 1-0581
301
1 5 6-8558
259
1 2 0-0387
300
1 5 5-8363
258
1 1 11-0192
299
1 5 4-8169
257
1 1 9-9998
298
1 5 3-7974
256
1 1 8-9803
297
1 5 2-7779
255
1 1 7-9609
296
1 5 1-7585
254
1 1 6-9414
295
1 5 0-7390
253
1 1 5-9219
188 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV
Table of the English Mint Value of Gold continued.
Fineness of
Gold
Value per Ounce
Fineness of
Gold
Value per Ounce
*. d.
s. (I.
252
1 1 4-9025
210
17 10-0854
251
1 1 3-8830
209
17 9-0659
250
1 1 2-8636
208
17 8-0465
249
1 1 1-8441
207
17 7-0270
248
1 1 0-8247
206
17 6-0076
247
1 11-8052
205
17 4-9881
246
1 10-7858
204
17 3-9687
245
1 9-7663
203
17 2-9492
244
1 8-7469
202
17 1-9298
243
1 7-7274
201
17 0-9103
242
1 6-7079
200
16 11-8909
241
1 5-6885
199
16 10-8714
240
1 4-6690
198
16 9-8519
239
1 3-6496
197
16 8-8325
238
1 2-6301
196
16 7-8130
237
1 1-6107
195
16 6-7936
236
1 0-5912
194
16 5-7741
235
19 11-5718
193
16 4-7547
234
19 10-5523
192 ,
16 3-7352
233
19 9-5329
191
16 2-7158
232
19 8-5134
190
16 1-6963
231
19 7-4939
189
16 0-6769
230
19 6-4745
188
15 11-6574
229
19 5-4551
187
15 10-6379
228
19 4-4356
186
15 9-6185
227
19 3-4161
185
15 8-5990
226
19 2-3967
184
15 7-5796
225
19 1-3772
183
15 6-5601
224
19 0-3578
182
15 5-5407
223
18 11-3383
181
15 4-5212
222
18 10-3189
180
15 3-5018
221
18 9-2994
179
15 2-4823
220
18 8-2799
178
15 1-4629
219
18 7-2605
177
15 0-4434
218
18 6-2410
176
14 11-4239
217
18 5-2216
175
14 10-4045
216
18 4-2021
174
14 9-3851
215
18 3-1827
173
14 8-3656
214
18 2-1632
172
14 7-3461
213
18 1-1438
171
14 6-3267
212
18 0-1243
170
14 5-3072
211
17 11-1049
169
14 4-2878
PART IV.
ENGLISH VALUE OF GOLD.
189
Table uf the English Mint Value of Gold continued.
Fineness of
ttold
Value per Ounce
Fineness of
Gold
Value per Ounce
s. d.
x. d.
168
14 3-2683
126
10 8-4512
167
14 2-2489
125
10 7-4318
166
14 1-2294
124
10 6-4123
165
14 0-2099
123
10 5-3929
164
13 11-1905
122
10 4-3734
163
13 10-1710
121
10 3-3530
162
13 9-1516
120
10 2-3345
161
13 8-1321
119
10 1-3151
160
13 7-1127
118
10 0-2956
159 13 6-0932
117
9 11-2761
158 13 5-0738
116
9 10-2567
157
13 4-0543
115
9 9-2372
156
13 3-0349
114
9 8-2178
155
13 2-0154
113
9 7-1983
154
13 0-9959
112
9 6-1789
153
12 11-9765
111
9 5-1594
152
12 10-9570
110
9 4-1399
151
12 9-9376
109
9 3-1205
150
12 8-9181
108
9 2-1010
149
12 7-8987
107
9 1-0816
148
12 6-8792
106
9 0-0621
147
12 5-8598
105
8 11-0427
146
12 4-8403
104
8 10-0232
145
12 3-8209
103
8 9-0038
144. 12 2-8014
102
8 7-9843
143
12 1-7819
101
8 6-9649
142
12 0-7625
100
8 5-9454
141
11 11-7430
99
8 4-9259
140
11 10-7236
98
8 3-9065
139
11 9-7041
97
8 2-8870
138
11 8-6847
96
8 1-8676
137
11 7-6652
95
8 0-8481
136
11 6-6458
94
7 11-8287
135
11 5-6263
93
7 10-8092
134
11 4-6069
92
7 9-7898
133
11 3-5874
91
7 8-7703
132
11 2-5679
90
7 7-7509
131
11 1-5485
89
7 6-7314
130
11 0-5290
88
7 5-7119
129
10 11-5096
87
7 4-6925
128
10 10-4901
86
7 3-6730
127
10 9-4707
85
7 2-6536
190 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV.
Table of the English Mint Value of Gold continued.
Fineness of
Gold
Value per Ounce
Fineo ess of
Gold
Value per Ounce
& s. d.
s. d.
84
7 1-6341
42
3 6-8170
83
7 0-6147
41
3 5-7976
82
6 11-5952
40
3 4-7781
81
6 10 5758
39
3 3-7587
80
6 9-5563
38
3 2-7392
79
6 8-5369
37
3 1-7198
78
6 7-5174
36
3 0-7003
77
6 6-4979
35
2 11-6809
76
6 5-4785
34
2 106614
75
6 4-4590
33
2 9-6419
74
6 3-4396
32
2 8-6225
73
6 24201
31
2 7-6030
72
6 1-4007
30
2 6-5836
71
6 0-3812
29
2 5-5641
70
5 11-3618
28
2 45447
69
5 10-3423
27
2 3-5252
68
5 9-3229
26
2 2-5058
67
5 8-3034
25
2 1-4863
66
5 7-2839
24
2 0-4669
65
5 6-2645
23
1 11 4474
64
5 5-2451
22
1 10-4279
63
5 4-2256
21
1 9-4085
62
5 3-2061
20
1 8-3890
61
5 2-1867
19
1 7-3696
60
5 1-1672
18
1 6-3501
59
5 01478
17
1 5-3307
58
4 11-1283
16
1 4-3112
57
4 10-1089
15
1 3-2918
56
4 9-0894
14
1 2-2723
55
4 8-0699
13
1 1-2529
54
4 7-0505
12
1 0-2334
53
4 6-0310
11
11-2139
52
4 5-0116
10
10 1945
51
4 3-9921
9
9-1750
50
4 2-9727
8
8-1556
49
4 1-9532
7
7-1361
48
4 09338
6
6-1167
47
3 11-9143
5
5-0972
46
3 10-8949
4
4-0778
45
3 9-8754
3
3-0583
44
3 8-8559
2
2-0389
43
3 7-8365
1
1-0194
PART IV. GOLD COINS IN THE U.S. OF AMERICA.
191
GOLD COINS IN THE UNITED STATES OP
AMERICA.
The following table of gold coins is taken from the
annual report of the Director of the United States Mint.
From the value of the gold coins a deduction of a
half of one per cent, is made to cover the cost of recoin-
age.
The weights of coins are usually expressed in grains,
but in this table they have been reduced to troy ounces
and decimals ; but these weights are readily converted
into grains again by multiplying them by 480, or grains
into ounces and decimals by dividing them by 480.
U.S.A. gold eagle, weighing 258 grs. or 0*5375 oz., is
worth $10-00.
Table of the Value of Gold Coins in the United States of America.
Country
Denominations
Weight
Fine-
ness
Value
Value
after De-
duction
I
Oz. Dec.
lOOOths
$
$
Australia .
Pound of ] 852
0-281
916-5
5-32-37
5-29-71
Australia .
Sovereign of '55-60
0-256-5
916
4-85-58
4-83-16
Austria
Ducat .
0-112
986
2-28-28
2-27-04
Austria
Souverain
0-363
900
6-75-35
6-71-98
Austria
New Union Crown
(assumed)
0-357
900
6-64-19
6-60-87
Belgium .
Twenty-five francs
0-254
899
4-72-03
4-69-67
Bolivia
Doubloon
0-867
870
15-59-25
15-51-46
Brazil
Twenty milreis
0-575
917-5
10-90-57
10-85-12
Central America
Two escudos .
0-209
853-5
3-68-75
3-66-91
Central America
Four reals
0-027
875
0-48-8
0-48-6
Chili
Old doubloon
0-867
870
15-59-26
15-51-47
Chili
Ten pesos ' condor '
0-492
900
9-15-35
9-10-78
Denmark .
Ten thaler .
0-427
895
7-90-01
7-86-06
Ecuador .
Four escudos
0-433
844
7-55-46
7-51-69
England .
Pound or sovereign,
new .
0-256-7
916-5
4-86-34
4-83-91
England .
Pound or sovereign,
average
0-256-2
916
4-84-92
4-82-50
France
Twenty f rancs,new
0-207-5
899-5
3-85-83
3-83-91
France
Twenty francs, av.
0-207
899
3-84-69
3-82-77
192 ENGLISH AND AMEEICAN VALUES OF GOLD. PART IV.
Table of the Value of Gold Coins continued.
Country
Denominations
Weight
Fine-
ness
Value
Value
after De-
duction
Oz. Dec.
lOOOths
$
Germany, North
Ten thaler .
0-427
895
7-90-01
7-86 06
Germany, North
Ten thaler, Prussian
0-427
903
7-97-07
7-93-OD
Germany, North
Krone (crown)
0-357
900
6-64-20
6-60-88
Germany, South
Ducat .
0-112
986
2-28-28
227-14
Greece
Twenty drachms .
0-185
900
3 44-19
3-42-47
Hindostan
Mohur .
0-874
916
7-08-18
7-04-64
Italy
Twenty lire .
0-207
898
3-84-26
382-34
Japrtn
Old cobang .
0362
568
4-44-0
4-41-8
Japan
New cobang .
0-289
572
3-57-6
3-55-8
Mexico
Doubloon, average
0-867-5
866
15-52-98
15-45-22
Mexico
Doubloon, new
0-867-5
870-5
15-61-05
15-53-25
Naples
Six ducati, new
0-245
996
5-04-43
5-01-91
Netherlands
Ten guilders .
0-215
899
3-99-56
3-97-57
New Granada .
Old doubloon
(Bogota) .
0-868
870
15-61-06
15-53-26
New Granada .
Old doubloon
(Popayan)
0-867
858
15-37-75
15-30-07
New Granada .
Ten pesos, new
0-525
891-5
9-67-51
9-62-68
Peru .
Old doubloon
0-867
868
15-55-67
1547-90
Peru .
Twenty soles (solde
oro) .
1-035
898
19-21-8
19-12-2
Portugal .
Gold crown .
0-308
912
5-80-66
5"77"76
Prussia
New Union crown
(assumed) .*
0-357
900
6-64-19
6-60-87
Rome
2^ scudi, new
0-140
900
2-60-47
2-59-17
Russia
Five roubles .
0-210
916
3-97-64
3-95-66
Spain
100 reals
0-268
896
4-96-39
4-93-91
Spain
80 reals
0-215
869-5
3-86-44
3-84-51
Sweden
Ducat .
0-111
975
2-23-72
2-22-611
Tunis
25 piastres .
0-161
900
2-99-54
2-98-05
Turkey
100 piastres .
0-231
915
4-3693
434-75
Tuscany .
Sequin .
0-112
999
2-31-29
2-30-14
Explanation of Gold Table.
The values per oz. of gold in the following tables are
computed from the simple formula that 387 oz. of pure
gold (1,000 fine) are worth $8,000. Hence 1 oz. is worth
$20-671834625 and the r ^-of an oz. (decimally expressed
as -001 fine) is worth $0-020671834625.
What we usually call fineness, therefore, is simply the
PART IV. GOLD COINS IN THE U.S. OF AMERICA. 193
weight of fine metal contained in any given quantity of
mixed metals or alloys. For instance, in a gold or silver
bar which is reported to be 850 fine, it is simply meant
that in 1,000 parts by weight 850 are fine gold or fine
silver, as the case may be.
In our mints the value of gold is computed from
standard weight that is, gold which is 900 fine, that
being the fineness of our gold coin as required by law.
The formula in this case is, 43 oz. of standard gold are
worth $800. Hence multiply standard ozs. by 800 and
divide by 43, and you obtain the value.
Example. Take 123 T W oz. at 843 fine, and we ob-
tain the result thus :
123*13 oz. gross weight.
843 fineness of gold.
36939
49252
98504
U.S. standard 900 ) 103J98-59 oz. of fine gold.
115331
800
43 ) 92264-800
#2145-69 value.
To find value per oz., divide total value (2145-69) by
standard ozs. (115-331), and you have $18-60.46, which
will be seen, by reference to the table, is the value of 1 oz.
of gold at 900 fine.
The value in this case would have been ascertained
o
194 ENGLISH AND AMERICAN VALUES OF GOLD. PART IV.
thus : By reference to the gold table and opposite '843
the value of 1 oz. -843 fine is #17-4264. Hence
123-13
174264
492-52
73878
24626
49252
86191
12313
2145-69 value.
PART IV. VALUE OF GOLD IN THE U.S. OF AMERICA. 195
Table of the Value of Gold per Ounce Troy, at Different Degrees
of Fineness, in the United States of America.
B
^H CO
1 1
3
1 5
3 ^
1 I I
a)
I s
8
E
1 <
00-00
10
20-67
20
41-34
30
62-02
40
82-69
i
01-03
21-71
42-38
63-05
83-72
i
02-07
II 2
22-74
21
43-41
31
64-08
41
84-75
i
03-10
4-
23-77
1
44-44:
|
65-12
85-79
2
04-13
12
24-81
22
45-48
32
66-15
42
86-S2
1
05-17
i
25-84
i
46-51
i
67-18
A
87-86
3 2
06-20
13
26-87
23
47-55; 33"
68-22
43'
88-89
I 2
07-24
27-91
1
48-58 1
i
69-25
1
89-92
4
08-27
14
28-94
24
49-61 :
34
7028
44
90-96
i
09-30
l
29-97
i
50-65
_L
71-32
i
91-99
5
10-34
15
31-01
25 2
51-68
35 2
72-35
45
93-02
1
11-37
i
32-04
l
52-71
i
73-39
JL
94-06
6
12-40
16
33-07
26'
53-75
36
74-42
46
95-09
i
13-44
1
34-11
1
54-78
75-45
l
96-12
7'
14-47
17"
35-14
27'
55-81
37
76-49
47
97-16
i i
15-50
1
36-18
l
56-85
i.
77-52
^
98-19
8
16-54
is'
37-21
28
57-88
38
78-55
48
99-22
17-57
|
38-24
|
58-91
i
79-59
i
1 00-26
9
18-60
19
39-28
29
59-95
39'
80-62
49
1 01-29
*
19-64
2
40-31
*
60-98
*
81-65
*]
1 02 '33
|
1 -s
H
8
1 1
Q
1
E
2 CO
5 "S
1
1
1 I
5 d
o>
e
S
I 1
50
1 03-36
60
1 24-03
70
1 44-70
80
1 65-37
90
1 86-05
i
1 04-39
i
1 25-06
i
1 45-74
J
1 66-41
^
1 87-08
51
1 05-43
61
1 26-10
71
1 46-77
81
1 67-44
91
1 88-11
i
1 06-46
i
1 27-13
i
1 47-80
1
1 68-48
1
1 89-15
52'
1 07-49
62'
1 28-17
72'
1 48-84
82'
1 69-51
92
1 90-18
i
1 08-53
i.
1 29-20
i
1 49-87
i
1 70-54
i
1 91-21
53'
1 09-56
;63
1 30-23
73
1 50-90
83 2
1 71-58
93
1 92-25
1
1 10-59
^
1 31-27
i
1 51-94,
l
1 72-61
i
1 93-28
54'
1 11-63
64
1 32-30
74
1 52-97
84'
1 73-64
94
1 94-32
i
1 12-66
i
1 33-33
i
54-01
i
1 74-68
i
1 95-35
55
1 13-70
65
1 34-37
75
55-04
85'
1 75-71
95'
1 96-38
l
1 14-73
i
1 35-40
i
56-07
i
1 76-74
i
1 97-42
56 2
1 15-76
66
1 36-43
76
57-11 i
86 2
1 77-78
96'
1 98-45
1
1 16-80
i
1 37-47
1
58-14)
i
1 78-81
|
1 99-48
57
1 17-83
67
1 38-50
77
59-171
87
1 79-84
97
2 00-52
1 18-86
i
1 39-53
i
60-21
i
1 80-88
^
2 01-55
68
1 19-90
68
1 40-57 !
78
61-24
88"
1 81-91
98
2 02-58
i
1 20-93
1 41-60
l
62-27
i
1 82-95
2 03-62
59
1 21-96
69
1 42-641
79
1 63-31
89'
1 83-98
99'
2 04-65
*
1 23-00
*
1 43-67 |
2
1 64-34
*
1 85-01
2
2 05-68
o 2
196 ENGLISH AND AMERICAN VALUES OF GOLD, PART IV.
Table of the Value of Gold continued.
0)
| 42
'
p 2
2
i "
o
2 w
o
1 a
1
1
a s
1 <3
1
1 B
E
1 i
100
2 06-72
110
2 27-39
120
2 48-06
130
2 68-73
140
2 89-41
\
2 07-75
2 28-42
I
2 49-10 j
i
2 69-77
1
2 90-44
101
2 08-79
111
2 29-46
121
2 50-13
131"
2 70-80
141
2 91-47
ft
2 09-82
2 30 49
l
2 51-16 | ft
2 71-83
JT 2 92-51
102
2 10-85
112
2 31-52
122
2 52-20
132
2 72-87
142 j 2 93-54
ft
2 11-89
1
2 32-56
l
2 53-23
ft
2 73-90
ft! 2 94-57
103"
2 12-92
113'
2 33-59
123'
2 54-26
133"
2 74-94
143"
2 95-61
i
2 13-95
i
2 34-63
ft
2 55-30;
2 75-97
ft
2 96-64
104
2 14-99
114
2 35-66
124
2 56-33 j
134
2 77-00
144"
2 97-67
ft
2 16-02
ft
2 36-69
2 57-36
ft
2 78-04
i
2 98-71
105
2 17-05
115
2 37-73
125"
2 58-40 |
135"
2 79-07
145"
2 99-74
i
2 18-09
1
2 38-76
l
2 59-43
^
2 80-10
ft
3 00-78
106
2 19-12
116
2 39-79
126'
2 60-46
136'"
2 81-14
146"
3 01-81
i
2 20-16
l
2 40-83
2 61-50'
.j.
2 82-17
i
3 02-84
L07'
2 21-19
117
2 41-86
127
2 62-53
137'
2 83-20
147'
3 03-88
ft
2 22-22
^
2 42-89
l
2 63-57 '
i
2 84-24
1
3 04-91
108"
2 23-26
118
2 43-93
128
2 64-60
138"
2 85-27
148"
3 05-94
i
2 24-29
2 44-96
ft
2 65-63
2 86-30
Jf
3 06-98
109
2 25-32
119'
2 45-99
129
2 66-67
139
2 87-34
149
3 08-01
*
2 26-36
ft
2 47-03
ft
2 67-70
ft
2 88-37
ft
3 09-04
q
1 3
q
1 3
2
1 5
a
1 |
2 .
s
? s
Q
s
S
1 o
&
1 *
1 <3
K
1 i
150
3 10-08
160
3 30-75
170
3 51-42
180
3 72-09
190
3 92-76
i
3 11-11
i
3 31-78
\
3 52-45
\
3 73-13
ft! 3 93-80
151
3 12-14
161
3 32 82
171
3 53-49
181
3 74-16
191
3 94-83
ft
3 13-18
' i
3 33-85
i
3 54-52
ft
3 75-19
i
3 95-87
152"
3 14-21
162
3 34-88
172
3 55-56
182
3 76-23
192
3 96-90
i
3 15-25
i
3 35-92
\
3 56-59
ft
3 77-26
k
3 97-93
153
3 16-28
163
3 36-95
173
3 57-62
183"
3 78-29
193 3 98-97
i
3 17-31
ft
3 37-98
ft
3 58-66
i
3 79-33
\. 4 00-00
154
3 18-35
164
3 39-02
174
3 59-69
184
3 80-36
194
4 01-03
i
3 19-38
ft
3 40-05
i
3 60-72
k
3 81-40
\
4 02-07
155
3 20-41
165
3 41-09
175
3 61-76
185
3 82-43
195
4 03-10
ft
3 21-45
^ 3 42-12
ft
3 62-79
*
3 83-46
k
4 04-13
156
3 22-48
166"! 3 43-15
176
3 63-82
186
3 84-50
196 4 05-17
i
3 23-51
ft{3 44-19
i
3 64-86
ft
3 85-53
% 4 06-20
157
3 24-55
167"! 3 45-22 177"
3 65-89
187
3 86-56
197
4 07-24
i
3 25-58
ftj 3 46-25
| 3 66-93
1 \
3 87-60
i
4 08-27
158
3 26-61
168"
3 47-29
178"
3 67-96
188
3 88-63
198": 4 09-30
i
3 27-65
i
3 48-32
|
3 68-99
! *
3 89-66
4 10-34
159
3 28-68
169"
3 49-35
179
3 70-03
189"
3 90-70
199 4 11-37
i
3 29-72
J3 50-39
i
3 7106
i i
3 91-73J! i:4 12-40
PART IV. VALUE OF GOLD IN THE U.S. OF AMERICA. 197
Table of the Value of Gold continued.
__
1 1
0>
&
S
1 s
|
I 1
1
1 1
1
1 i
200
4 13-44
210
4 34-11 ! 220
4 54-78
230
4 75-45
240
4 96-12
4 14-47
! 4 35-14 i
4 55-81
i
4 76-49
i
4 97-16
201
4 15-50
211" 4 36-18 221
4 56-85
231
4 77-52
241
4 98-19
i
4 16-54
^ 4 37-21 I! ^
4 57-88
i
4 78-55
i
4 99-22
202
4 17-57
212 :4 38-24 222
4 58-91 232"
4 79-59
242
5 00-26
i 4 18-60
i 4 39-28 ! i
4 59-95
& 4 80-62
i
5 01-29
203
4 19-64
213"
4 40-31 ; 223
. 4 60-98 :233"
4 81-65 f
243'
5 02-33
i 4 20-67
4 41-34
4 62-02 j| | 4 82-69
i
5 03-36
204"
4 21-71
214" 4 42-38 224"
4 63-05 234 4 83-72
244'
5 04-39
i
4 22-74
i 4 43-41
J
1 4 64-08
; 4 84-75
I
5 05-43
205
4 23-77
215 4 44-44 225
4 65-12
235
4 85-79
245
5 06-46
i
4 24-81
1
4 45-48
i
4 66-15
i 4 86-82
i
5 07-49
206
4 25-84
216
4 46-51 226"
|4 67-18
236"
4 87-86
246
5 08-53
^.
4 26-87
4 47-55 I |
4 68-22
^ 4 88-89
*
5 09-56
207"
4 27.-91
217 4 48-58 227"
i 4 69-25
'237
4 89-92
247
5 10-59
4 28-94
^ 4 49-61 i| \
4 70-28 | 4 90'96
i
5 11-63
208
4 29-97
218
4 50-65 228
4 71-32
238
4 91-99
248
5 12-66
i
4 31-01
i
4 51-68
4
- 4 72-35
4 93-02
1
5 13-70
209
4 32-04
219
4 52-71 229
4 73-39
239
4 94-06
249
5 14-37
2
4 33-07
4 53-75
i
4 74-42
2
4 95-09
*
5 15-76
P a
2
I |
1 3
2
3 ti
g
1 3
S
o ^
1
ft S
I
1 <
&
1
2
i
I 1
2
2 5
1 1
o
1 2
1 &
400
8 26-87
410
8 47-55
'420
8 68-22
430
8 88-89
440
9 09-56
8 27-91
8 48-58
8 69-25
*
8 89-92
*
9 10-59
401
8 28-94
411
8 49-61
421
8 70-28
431
8 90-96
441
9 11-63
^
8 29-97
i
8 50-65 |
8 71-32
\
8 91-99
i
9 12-66
402"
8 31-01
412
8 51-68 422
8 72-35
432
8 93-02
442
9 13-70
*
8 32-04
*
8 52-71
i
8 73-39
8 94-06
\
9 14-73
403
8 33-07
413
8 53-75
423
8 74-42
433
8 95-09
443
9 15-76
*
8 34-11
8 54-78
i
8 75-45
8 96-12
k
9 16-80
404
8 35-14
414
8 55-81
424
8 76-49
434
8 97-16
444
9 1783
*
8 36-18
8 56-85 |
8 77-52
i
8 98-19
*
9 18-86
405
8 37-21
415
8 57-88 425
8 78-55
435
8 99-22
445
9 19-90
8 38-24
8 58-91
i
8 79-59
9 00-26
i
9 20-93
406"
8 39-28
416
8 59-95
426
8 80-62
436
9 01-29
446
9 21-96
*
8 40-31
8 60-98
8 81-65
9 02-33
9 23-00
407
8 41-34
417
8 62-02
427
8 82-69
437
9 03-36
447
9 24-03
|
8 42-38
8 63-05
8 83-72
\
9 04-39
i
9 25-06
408
8 43-41
418
8 64-08 428"
8 84-75
438
9 05-43
448
9 26-10
*
8 44-44
i
8 65-12
8 85-79
9 06-46
i
9 27-13
409 8 45-48
419
8 66-15 429"
8 86-82
439
9 07-49
449
9 28-17
i
8 46-51
\
8 67-18
8 87-86
}
9 08-53
\
9 29-20
8
s
1 1
1 *
2
1 1
1 *
2
1
| |
1 S
1 .2
^j S
p CJ>
650 13 43-67
660 13 64-33
670 13 85-01
680
14 05-68
690
14 26-86
13 44-70
13 65-37
|13 86-05
i
2
14 06-72
14 27-39
651 13 45-74
661 i!3 66-41
671
13 87-08
681
14 07-75 691
14 28-42
13 46-77
13 67-44
ll3 88-11
14 08-79
14 29-46
652
13 47-80
662 |13 68'48
672 13 89-15
682
14 09-82 692
14 30-49
13 48-84
13 69-51
13 90-18
*
14 10-85||
14 31-52
653 :13 49-871 663" 13 70'54
673 13 91-21
683
14 11-89
693
14 32-56
13 50-90| 13 71-58
13 92-25
14 12-92
\
14 33-59
654
13 51-94 664
13 7261
674 113 93-28
684
14 13-95
694
14 34-63
13 52-97
13 73-64
13 94-3'2
14 14-99
1
14 35-66
655 13 54-01 665~|13 74'68
675
13 95'35
685
14 16-02
695
14 36-69
|13 55-04
,13 75-71
13 96-38
14 17-05
14 37-73
656" |13 56-07
666 |l3 76-74
676
13 97'42
686
14 18-09
696
14 38-76
13 57-11
13 77-78
*
13 98-45
%
14 19-12
i
14 39-79
657"
13 58-14 667
13 78-81
677
13 99'48
687
14 20-16
697
14 40-83
.13 59-17
13 79-84
14 00-52
14 21-19
14 41-86
658
13 60-21 668"
13 80-88
678"
14 01-55
688
14 22-22
698
14 42-89
*
13 61-24
*
13 81-91
*
14 02-58
14 23-26
\
14 43-93
659
13 62-27
669
13 82-95
679
14 03-62
689
14 24-29
699
14 44-96
*
13 63-31
13 83-98
i
14 04-65
14* 25-32
\ 14 45-99
202 ENGLISH AND AMERICAN VALUES OF GOLD. PABT IV,
Table of the Value of Gold continued.
I
1 1
3
1 *
"o
Q O
1
I 3
1 *
I i
a
S
1 1
1 3
700
14 47-03
710
14 67-70
720
14 88-37
730
15 09-04
740
15 29-72
*
14 48-06
*
14 68-73
1 i
14 89-41
*
15 10-08
tH5 30-75
701
14 49-10
711
14 69-76
721
14 90-44
731
15 11-11
741"
15 31-78
*
14 50-13
*
14 70-80
*
14 91-47
i
15 12-14
i
15 32-82
702
14 51-16
712
14 71-83
722
14 92-51
732
15 13-18
742 115 33-85
i
14 52-20
*
14 72-87
i
14 93-54
1
15 14-21
i
15 34-88
703
14 53-23
713 14 73-90
723
14 94-57
733
15 15-25
743
15 35-92
i
14 54-26
114 74-94
?
14 95-61
i
15 16-28
i
15 36-95
704
14 55-30
714
14 75-97
724
14 96-64
734
15 17-31
744
15 37-98
*
14 56-33
*
14 77-00
\
14 97-67
i
15 18-35
i
15 39-02
705
14 57-36
715
14 78-04
'725
14 98-71
735
15 19-38
745
15 40-05
\
14 58-40
i
14 7907
\
14 99-74
15 20-41
i
15 41-09
706
14 59-43
716
14 80-10
,726
15 00-78
736 15 21-45
746
15 42-12
*
14 60-47
*
14 81-14
\
15 01-81
115 22-48
i
15 43-15
707
14 61-50
717
14 82-17
727
15 02-84
737 16 23-51
747
15 44-18
*
14 62-53
*
14 83-20
"2
15 03-88
1
15 24-55
-j
15 45-22
708
14 63-57
718 114 84-24
'728
15 04-91
738
15 25-58
748
15 46-25
\
14 64-60
14 85-27
1 15 05-94
i
15 26-61
-*
15 47-29
709
14 65-63
719 !l4 86-30
729 15 06-98
739
15 27-65
749
15 48-32
\
14 66-67
14 87-84 1 115 08-01
115 28-68
115 49-35
1
2 w
1 I
Dollars
Cents
1
1 !
Q
1
1 i
8
R
a o
750
15 50-39
760
15 71-06
770
15 91-73
780
16 12-40
790
16 33-07
i
15 51-42
i
15 72-09
1
15 92-76
i
16 13-44
16 34-11
751
15 52-45
761
15 73-13
771
15 93-80
781
16 14-47
791 |16 35-14
15 53-49
|
15 74-16
15 94-83
i
16 15-50
116 36-18
752
15 54-52
762
15 75-19
772
15 95-87
782"
16 16-54
792"|16 37-21
i
15 55-56
i
15 76-23
l
15 96-90
i
16 17-57
116 38-24
753'
15 56-59
763"
15 77-26
773 15 97-93
783'
16 18-60
793" 16 39-28
i
15 57-62
*
15 78-29
115 98-97
i
16 19-64
16 40-31
754
15 58-66
764
15 79-33
774 |16 OO-Ooi'784
16 20-67
794 16 41-34
i
15 59-69
i;i5 80-36
16 01-03
16 21-71
116 42-38
755'
15 60-72
765
15 81-40
775 16 02-07! 785
16 22-74
795 J16 43-41
15 61-76
15 82-43
116 03-10|! i
16 23-77
i ! 16 44-44
756
15 62-79
766
15 83-46
776 il6 04-131,786
16 24-81
796
16 45-48
i
15 63-82
i
15 84-50
116 05-17
16 25-84
*
16 46-51
757
15 64-86
767
15 85-53
777 16 06-20;:787
16 26-87
797
16 47-55
i
15 65-89
15 86-56
1 16 07-24
i
16 27-91
16 48-58
758
15 66-93
768
15 87-60
778 16 08-27
788'
16 28-94
798'
16 49-61
i
15 67-96
i
15 88-63
116 09-30
i.
16 29-97
i
16 50-65
759
15 68-99
769"
15 89-66
779 16 10-34
789"
16 31-01
799"
16 51-68
*
15 70-03
*
15 90-70
116 11-37
2
16 32-04
*
16 52-71
PAKT IV. VALUE OF GOLD IN THE U.S. OF AMERICA. 203
Table oftlie Value of Gold continued.
.
I
2 03
1 EG
o
c3 ^ '
C>
ci OT
Q)
cfl -JS
S
o5 co
1 1
1 1
1
1 3
(2
1 1
a
1 i
800
16 53-75
810
16 4-42
! 820
16 95-09
830
17 15-70
840
17 36-43
i
16 54-78
16 75-45
16 96-12
17 16-80
17 37-47
801
16 55-81
811 2
16 76-49 821
16 97-16
831
17 17-83
841 17 38-50
i
16 56-85
16 77-52
16 98-19
17 18-86
17 39-53
802
16 57-88
812
16 78-55
822
16 99-22
832
17 19-90
842 !17 40-57
i
16 58-91
16 79-59
i
17 00-26
17 20-93
17 41-60
803
16 59-95
813
16 80-62
823
17 01-29
833
17 21-96
843 17 42-64
i
16 60-98
16 81-65
17 02-33
17 23-00
J|17 43-67
804
16 62-02
814
16 82-69
824
17 03-36
834
17 24-03
844
17 44-70
16 63-05
16 83-72
^
17 04-39
17 25-06
17 45-74
805
16 64-08
815
16 84-75
1825
17 05-43
835
17 26-10
845
17 46-77
i
16 65-12
i
16 85-79
\
17 06-46
I
17 27-13
17 47-80
806
16 66-15
816
16 86-82
'826
17 07-49
836
17 28-17
846
17 48-84
16 67-18
i
16 87-86
i
17 08-53
i
L7 29-20
i!l7 49-87
807
16 68-22
817
16 88-89
827
17 09-56
837
17 30-23
847 17 50-90
i
16 69-25
16 89-92
17 10-59
17 31-27
17 51-94
808
16 70-28
818
16 90-96
828
17 11-63
838
17 32-30
848 17 52-97
16 71-32
16 91-99
17 12-66
17 33-33
17 54-01
809
16 72-35
819
16 93-02
829
17 13-70
839
17 34-37
849 17 55-04
*
16 73-39
*
16 94-06
17 14-73
*
17 35-40
*
17 56-07
2
1 -S
05
<>
CO
tri *
1 -e
Q
1
1 ^
1 <
c
. g
p
a
1 1
850
17 57-11
860
17 77-78
870
17 98-45
880
18 19-12
890
18 39-79
17 58-14
*
17 78-81
i
17 99-48
1
18 20-16
i
18 40-83
851
17 59-17
861
17 79-84
871
18 00-52
881
18 21-19
891
18 41-86
1
17 60-21
\
17 80-88
] i
18 01-55
18 22-22
i
18 42-89
852
17 61-24
862
17 81-91
872
18 02-58
882
18 23-26
892'
18 43-93
4
17 62-27
J
17 82-95
i
18 03-62
i
18 24-29
i
18 44-96
853"
17 63-31
863
17 83-98
873
18 04-65
883
18 25-32
893 2
18 45-99|
1
17 64-34
i
17 85-01
18 05-68
-i
18 26-36
18 47-03
854
17 65-37
864'
17 86-05
874
18 06-72
884
18 27-39
894
18 48-06
-|
17 66-41
i
17 87-07
i
18 07-75
i
18 28-42
i
18 49-10
855
17 67-44
865
17 88-11
875
18 08-79
885
18 29-46
895
18 50-13
i
17 68-48
17 89-15
*
18 09-82
18 30-49
18 51-16
856
17 69-51
866
17 90-18
876
18 10-85
886
18 31-52
896
18 52-20
i
17 70-54
i
17 91-21
i
1 Q
18 11-89
i
18 32-56
i
18 53-23
857
17 71-58
867
17 92-25
877^
18 12-92
887'
18 33-59
897 2
18 54-26
i
17 72-61
^
17 93-28
18 13-95
i
18 34-63
i
18 55-30
858
17 73-64
868
17 94-32
878 2
18 14-99
888
18 35-66
898'
18 56-33
3
17 74-68
i
17 95-35
i
18 16-02
i
18 36-69
i
18 57-36
859"
17 75-71
869
17 96-38
879
18 17-05
889'
18 37-73
899
18 58-40
17 76-74
A 17 97-42
18 18-09
18 38-76
18 59-43
204 ENGLISH AND AMERICAN VALUES OF GOLD PART IV.
Table of the Value of Gold continued.
s
! I
1
1 1
3
1
S 1
1 a
|
1 1
*
m
P o
900
18 60-46
010
18 81-14
920
19 01-81
980
19 22-48
940 19 43 15
i
18 61-50
18 82-17
19 02-84
4
19 23-51
419 44-19
901 2
18 62-53
911
18 83-20
921
19 03-88 931"
19 24-55
941" 19 45-22
18 63-57
18 84-24
19 04-91 i 4 19 25-58
419 46-25
902
18 64-60
912
18 85-27 922
19 05-94
982
19 26-61
942" j!9 47-29
18 65-63
18 86-30
4
19 06-98
19 27-65
19 48-32
903
18 6667
9L3
18 87*84 J988"
19 08-01
933
19 28-68
943* 19 49-35
18 67-70
18 88-37 4
L9 0904 419 29-72
4
19 50-39
904
18 68-73
914
18 89-41 1 924"
19 1008 934" 19 30-75
944"
10 51-42
18 69-77
18 90-4411
19 11-11
19 81-78
4 10 52-45
905
18 70-SO
915
18 91-47 925
19 12-14:985"
19 32-82
945" 19 53-49
18 71-83
18 92-51
19 13-18
19 83-S5
419 54-52
906
18 72-87
916
18 93-54
926
19 14-21
936
19 34-88
946" 19 55-56 1
18 73-90
18 9457
19 15-25
1 *
19 35-92
4
19 56-59
907
18 74-94
917
18 95-61
927
19 16-28
937
19 36-95
947"
19 57-62
4
18 75-97
18 96-64
19 17-31
4
19 37-98
4
19 58-66
908
18 77-00
918
18 97-67i928"
19 18-35 938"
19 39-02
948
19 59-69
18 78-04
4
18 98-71
19 1938]
19 40-05
4
19 60-72
909 i!8 79-07
919"
18 99-74 929 19 20-41 939"
19 41-08
949"
19 61-76
18 80-10
19 00-78
19 21-45
*
19 42-12
*
19 62-79
S
I 5
S
1 *
t
I f
(U
a
2
i -
1 3
1 - <
i
1 3
S
1 o S
i
1 1
950
19 63'82
960
19 84-50
970
20 05-17
980
20 25-8-1
990
20 46-51
*
19 64-86
*
19 85-53
i
20 06-20
20 26-87 !
20 47-55
951
19 65-89
961
19 86-56
971
20 07-23
981
20 27-91 5)91"
20 48-58
19 66-93
i
19 87-60
i
20 08-27
1
20 28-9-1 J
20 49-61
952
19 67-96
962
19 88-63
972
20 09-30
982
20 29-97 992"
20 50'65
19 68-99
19 89-66
1
20 10-34
4
20 31-01!
20 51-68
953
19 70-03
963
19 90'70
973
20 11-37
983'
20 82-04 993
20 52-71
i
19 71-06
i
19 91-73
20 12-40
i
20 33-07 i
20 53-75
954
19 72-09
964
19 9276
974
20 13-44
984
20 34-11 994"
20 54-78
^
19 73-13
19 93-80
i
20 14-47
A
20 35-14
i
20 55-81
955
19 74-16
965
19 94-83
975"
20 15-50 985"
20 36-18 >995" 20 56-85
1
19 75-19
i
19 95-87
20 16-54
20 37-21
20 57-88
956"
19 76-23 1966
19 96-90
976
20 17-57
986
20 38-24 996 20 58*91
i
19 77-26]
19 97-93
20 18-60
20 39-28 1 ^20 59-95
957
19 78-29
967
19 98-97
977
20 19-64
987
20 40-31 997" 20 60-98
19 79-33
1
20 00-00
20 20-67
20 41-34 20 62-02
958 19 80-36
968
20 01-03
978 20 21-70
988 20 42'38 :998 20 63-05
i
19 81-40
20 0207
42022-74 2043-41! 42064-08
959"
19 82-43
! 969
20 03 10
979" [20 23-77
989 20 44-44
999 20 65-12
19 83-46 i 420 04-13
20 24-81
20 45 48
420 66-15
I
ii 1000 20 67-1 S
INDEX.
ALU
A LUMINIUM, qual. determina-
J\. tion, 52
Amalgams described, 136
Ammonia, 33
carbonate of, 33
Ammonium, sulphide of, 33
Anthracite, 172
Antimony, qual. determination, 65,
56
Anvil, steel, 23
Aragonite, 49
Argentiferous sulphide of copper,
98
Argentite, 97
Argol, 33
Arsenic, metallic, 33
qual. determination, 80-82
Assay balance, description and
capacity, 17, 18
grain weights, 18
Attwood, Melville, on the batea,
29, 30
Azurite, 146
BALANCE for large quantities
and capable of weighing 32
oz., 19-22
experiments with large, 22
Barium, qual. determination, 47
Batea, 29-32
Beaker glasses, 28
Berthier, on the heating power in
coals, 174, 175
Berzelius, on the form of blow-
pipe, 4
on the blowpipe lamp, 7
BRO
Berzelius, on preparing pure iron,
39
on fluorine, 75
on chlorine, 75
on bromides and chlorides, 77
on palladium oxides, 89
Bismuth, pure, how to make, 38
qual. determination, 68, 69
native, 153
ores, 153
sulphide, 153
carbonate of, 153
acicular, 153
blende, 153
metallic description of, 153,
154
assay, a previous qualitative
examination, 154
roasting and fusing, 155
Blowpipe capabilities, 3
description, 4
tips, 4
mouthpiece, 4
how to use it, 5
- fuel, 6
Bone ash, 33
Boracic acid, 33
Borax, 32
Borers for charcoal, 24, 25
Bornite, 146
Boron, qual. determination, 83
Bottle for washing precipitates, i"J
drop, for holding acids, 29
Bournonite, 146
Bromine, qual. determination, 76,
77
Bromyrite, 98
206
INDEX
BEU
Brucite, 51
Brush, on blowpipe gas lamp, 10
/CADMIUM, qual. determination.
\J 65, 66
Cassium, qual. determination, 47
Calcium, qual. determination, 49,
50
Calomel, 135
Capsules, mixing, 26
Carbon, qual. determination, 82,
83
Cassiterite, 166
Cerargyrite, 98
Cerium, qual. determination, 89,
90
Chalcopyrite, 146
Charcoal as a blowpipe support,
12
holder, 27
Chilenite, 98
Chlorine, qual. determination, 75,
76
Chromium, qual. determination, 57
Cinnabar, 135
Coal, description of, and probablt
origin, and where found, 171.
172
hard (hard coal), 172
brown (brown coal), 172
caking (caking coal), 172
non-caking (non-caking coal),
172
cannel (cannel coal), 172, 173
assay, moisture determinatior ,
173
coke production, 173
the amount of ash, 174
heating power determina
tion, 174
sulphur estimation, 175, 17(
Cobalt, qual. determination, 61, 61
nitrate of, 33
ores, 164
- assay, 164, 165
Cobaltite, 164
Columbium, qual. determinatior,
91, 92
Copper oxide, 33
sulphate of, 33
FLA
Copper, pure, how to make, 37
qual. determination, 66
native, 145
glance, 146
red, 146
phosphate of, 146
arseniate of, 146
assay, classification, 146]
description of method adopt-
ed to extract the metal from
its matrix, 146, 147
roasting the ore, 147, 148
fusion of the roasted ore or
product, Class B, 148, 149
refining the copper and lead
alloy, Class C (a), 149
alloy of copper and anti-
mony, 150
Covelline, 146
Cupel mould, 29
Cupellation, method of, 106-108
Cupels,, how to make them, 29
Cyanosite, 146
Cylinder, hard-wood, for preparing
soda-paper cornets, 27
DIDYMIUM, qual. determina-
tion, 90, 91
Dishes, evaporating, 27, 28
Dolomite, how to distinguish from
ordinary limestone, 51, 52
Domeykite, 14G
Domeyko, on the assay of mer-
cury, 143-145
TWBOLITE, 98 1
Jj Epsomite, 51
Erbium, qual. determination, 91
Erythrite, 164
Explanation of American gold
table, 192-194
T7AHLEKZ, 98, 146
r Filter paper, 29
Fire-clay crucibles and capsules,
how to make them, 15, 16
Flames, oxidising and reducing,
10
INDEX
207
FLE
Fletcher, paraffin lamp, 9, 10
Fluorine, qual. determination, 75
Forbes, David, on colours of sub-
limates on charcoal, 43, 44
on the determination of the
silver globule obtained by cu-
pellation, 109-116
Forceps with platinum tips, 25
brass, 25
iron, 25
Franklinite, 160
Fuchs, on detection of oxygen, 73
Funnels, glass, 28
Furnace, description of the char-
coal furnace and holder em-
ployed in the distillation of
mercury and in the assays of
gold, silver, lead, &c., 142-144
GAHN on the construction of
the blowpipe, 4
Gold, pure, how to make, 35
qual. determination, 56
native, its forms and places of
occurrence, 125
alloys, native and artificial, 126
assay, explanation of the me-
thods of assaying, 126, 127
classification of, 127
of free milling ores, Class
A O), 127, 128
of pyrites, Class A (J), 128
of river and ocean sands,
Class A O), 128, 129
of alluvial deposits and
placer washings, Class A (d\
129
of slags, Class ,4 0), ] 30
of sweeps,' Class A (/), 130
universal method for ores
and minerals, Class A (#), 130
of alloys, coins, and fine
gold, Class B O), 130-132
quantity of lead required to
cupel different qualities of
gold, 131
separation from silver, 131,
132
of dust and nuggets, 132
in copper plates, 133
ISO
Gold'assay when more than 10 per
cent, of platinum is present,
133
containing iridium, 133
when palladium is present,
and not more than 10 per
cent, of platinum, 133
when platinum and silver
are present, 133, 134
when rhodium is present,
134
with mixed metals, as in
Class B (i), 134
a rapid assay of coins,
nuggets, &c., Class B (7), 134,
135
amalgams, 135
Glucinum, qual. determination, 84,
85
Graphite, 33
HAMMER, steel, for breaking
rocks, &c., 22
for flattening metallic but-
tons, 23
Hanks, Henry, on the batea, 31, 32
Hessite, 98
Holder, platinum wire, 14
Hydrochloric acid, 33
Hydrogen, qual. determination,
73, 74
Hydromagnesite, 51
TLMENITE, 160
I Indium, qual. determination, 68
lodyrite, 98
Iodine, qual. determination, 77
Iridium, qual. determination, 93
estimation of, 133
Iron, pure, how to make, 39, 40
- protosulpbate, 33
qual. determination, 57-61
native, 159
sulphides, 159
ores, 159
ore, brown, 159
carbonate of, 160
assay, description of the me-
thods adopted, 160-163
208
INDEX.
KUP
TTUPFERNICKEL, 163
jy
T AMBOKN, on blowpipe flames,
_L 10-12
Lamp, used by Plattner, 7
for burning alcohol, 9
for burning paraffin, 9
using gas according to Brush, 10 j
Lanthanum, qual. determination,
85,86
Lead oxychloride, 33
pure, how to make, 36
qual. determination, 66-68
native, 150
ores, 150
assay, classification of, 151
method employed and results
obtained by same, 151
preparation of sample and
instructions in fusion, &c., 151,
152
of Class B y 152
Lignite, 172
Litharge, 33
Lithia, Turner's method f detect-
ing, 72
Lithium, qual. determination, 72,
73
Litmus paper, 33
MAGNESITE, 51
Magnesium wire, 33
qual. determination, 50-52
Magnet, steel, 24
Makins, on the fusing power of
the blowpipe, 3
Malachite, 146
Manganese, qual. determination,
52-54
Menaccanite, 160
Mercury, pure, how to make, 38, 39
qual. determination, 71
description and occurrence of,
135
assay, classification of, 136, 137
preparation and description
of method adopted and mode
of making retorts to determine
Class A, 137-139
NIT
Mercury assay of Class 7?, 139
amalgams that spurt on heat
being applied, 140
of amalgams, 140-143
description of the steel
retorts, distillation pipe, re-
ceiver, &c., 141, 142
Millerite, 163
Mitchell, on estimation of sulphur
in coal, 175, 176
Molybdenum, qual. determination,
92, 93
Mortar, steel, 23
agate, 23
NICKEL, oxalate of, 33
qual. determination, 62,
63
ores, 163
white (white nickel), 163
antimonial, 163
-glance, 163
copper (copper nickel), 163
assay, 163, 164
and cobalt assays, the method
adopted, 165, 166
assay classification of , 166
roasting, 166
fusing with metallic
arsenic, 166, 167
nickel, cobalt, arsenic,
and iron, 167, 168
separating the cobalt
from the nickel by slagging,
168, 169
ores and products in
which nickel, cobalt, copper,
and iron are combined with a
small quantity of arsenic, 169,
170
when nickel, cobalt,
iron, and copper, &c., are
present, 170, 171
alloys of copper and
nickel, 171
poor ores requiring a
collecting agent, 171
Niobium, qual. determination, 91
Nitre, 33
Nitric acid, 33
INDEX.
209
NIT
Nitrogen, qual. determination, 74
Nitrous acid, 33
OSMIUM, qual. determination,
93
Oxygen, qual. determination, 73
"PALLADIUM, qual. determina-
JL tion, 88, 89
Pan, used with large balance, 21
Pans, horn, 19
metal, 19
Paper prepared for making cornets
in the silver and gold assays,
29
Pentlandite, 163
Periclase, 51
Phillips, J. A., on occurrence of
tin, 156
Phosphorus, qual. determination,
78-80
Phosphorus salt, 32
Platinum foil, 13
wire, 13
instructions how to use it, 14
spoons, 15
qual. determination, 71
Plattner, on blowpipe lamp, 7
on iron compounds, 59
on detecting cobalt in nickel
alloys, 62
on detecting a small quantity
of nickel in oxides of cobalt,
manganese, and iron, 63
on lithia, 72
on sulphur, 78
on sesquioxide of iron, 162
Pliers, steel, 26
Polybasite, 98
Potash, caustic, 33
carbonate of, 33
Potassa, neutral oxalate of, 32
- bisulphate of, 33
Potassium, cyanide of, 32
qual. determination of, 45, 46
Proustite, 97
Pyrargyrite, 97
Q
UAETZ, 33
SIL
T)HODIUM,qual. determination,
XI 93
Riders gold, 19
Roach, John, on the batea, 30
Rubidium, qual. determination, 47
Ruthenium, qual. determination, 89
SALT, common, 33
Saw for cutting charcoal, 13
Scorifier, 104
Screens, punched, 27
Selenic silver, 98
Selenium, qual. determination, 93,
94
Shears, cutting, 25
Sieves, wire, 27
Silicium, qual. determination, 83,
84
Silver, pure, how to make, 34
qual. determination, 56
native, 97
in sea water, 97
minerals and ores, 97, 98
in products and refuses, 98
explanation of the modus
operandi employed in assay-
ing its ores and compounds, 99
assay, classification, 99, 100
amount of lead required for
different ores, 101, 102
preparation of the ore and
the reduction to silver lead,
100-104
how to scorify and concen-
trate the silver lead, 104-106
of argentiferous molybde-
nite, 119, 120
of Class A (c), 120
of Class A (d), 120, 121
of Class A (0), being a gene-
ral method adapted to the
assay of silver ores, 121, 122
of Class B (a), being alloys
ready for cupellation, 122,
123
of alloys requiring cleansing
before cupellation, 123
of alloys and quantity of test
lead required, 123
of amalgams, 123
210
INDEX.
SIL
Silver assay, determination in brass
and black copper, 123, 124
- in antimony, tellurium, and
zinc, 124
in tin and gun metal, 124
- in silver-steel and iron, 124,
125
in alloys of lead or bismuth,
125
in copper coins, wire, and
cement, 125
Skutterudite, 164, 165
Smaltine, 164
Smyth, W.W., Prof., on the batea, 31
Soda, carbonate of, 32
Sodium, qual. determination, 46, 47
Spar, fluor, 33
Spoon, horn, 24
ivory, for mixing, 27
Stand to hold cupels, 27
Stein, on nitrogen, 74
Stephanite, 97
Sternbergite, 98
Strontium, qual. determination,
48,49
Sublimates on charcoal, colour,
43, 44
Sulphur, roll, 33
qual. determination, 77, 78
Sulphuric acid, 33
Synthetical assays, 109
HHABLE for calculating the gold
JL and silver in a ton of 2,240 Ibs.,
117, 118
for calculating the gold and
silver in a ton of 2,000 Ibs.,
118, 119
of English Mint value of gold,
179-191.
of the value of gold in the United
States of America, 195-205
Tantalum, qual. determination,
86, 87
Tellurium, qual. determination, 94
Terbium, qual. determination, 86
Thallium, qual. determination, 92
ZIE
Thorium, qual. determination, 92
Tiemannite, 135
Tin, pure, how to make, 37
qual. determination, 55
metallic, 156
assay, classification of, 156
oxides, 156
assay, fusion of pure oxides, 157
ores containing silica, 157,
158
- when sulphur, arsenic, and
tungsten are present, 158, 159
ores with less than 5 per
cent,, 159
Titanium, qual. determination,
69-71
Tubes, glass, open at both ends, 1 6
-- closed and bulb -shaped, 17
-- test, for parting gold and
silver, 28
Tungsten, qual. determination, 87,
88
Turner, on lithia, 72
on boron, 83
URANIUM, qual. determination,
87
Ure, Dr., on Berthier's process of
determining absolute heating
power, 175
VALUE of gold coins in the
United States of America,
191, 192
Vanadium, qual. determination, 88
Von Kobell, on tungstite, 87
TT70LFSBERGITE, 146
VV Wollastonite, 49
TTTTRIUM, qual. determination,
I 86
on distinguishing
i 1 limestones, 51
Zinc, qual. determination, 63, 64
Zirconium, qual. determination, 94
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