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c rv
THE
Blowpipe Manual.
BY
DR. THEODORE SCHEERER,
ProftKor of CkemUtrjf in the Royal Saxon Mining School at Freiberg.
TRANSLATED BOT
WILLIAM Sf CLARK,
AMHERST:
SfOKRS & MoCLOUD, PRINTERS.
mtm
THl mW TORK
PUBLIC LIBRARY
559405 l\
TILDEN '- .^u- -.V .
R 1931 U
» • • •
♦ • ' • • » •
• • • / . • • ;
•• • I
.•• •
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• t » , /•••••
• • '^ • • •
V
Translator's Preface.
This little manual has been prepared for the use of the
students of the Massachusetts Agricultural College.
Those who desire further information upon this most
>ortant subject are referred to Plattner's ^'jirt of
jaying with the Blowpipe."
N
Contents.
USB OF THE BLOWPIPE IN QUALITATIVE ANALYSIS.
Page.
Introdnctioii, ....... 9
I. The Blowpipe ITlaine and Articles necessary in assaying
qualitatively with the Blowpipe, . . .13
Oxidizing and Reducing Flames, . . .13
A. The Blowpipe, ...... 15
B. The Blowpipe Flame, . ' . . . 16 •
C. Supports and Holders for the substances to be heated, 16
(1) Charcoal, p 16. (2) Platinum Wire, p IT. (3)
Platinum Foil, p 18. (4) Platinum Spoon, p 18. (5)
Platinum Forceps, p 18. (6) Glass Tubes, p 18. (7)
Glass Matrasses, p 19.
D. Blowpipe Beagents, ..... 19
(1) Soda, p 19. (2) Borax, p 19. (3) Salt of Phos-
phorus, p 20. (4) Other Reagents, p 20.
E. Other Articles for use with the Blowpipe, . . 21
II. Qualitatiye Examination with the Blowpipe, . 22
Order of the Tests, . . . .22
1. Test in Glass Matrass, . .22
Substances which, under certain circumstances, may
be detected in this way : Water, Sulphur, Selenium,
Tellurium, Arsenic, Quicksilver, Oxygen, Ammonia,
Fluorine, Chlorine, Bromine, Iodine, Nitric Acid.
2. Test in open Glass Tube, . • .25
Substances which, under certain circumdtances, may
be detected in this way : Sulphur , ^^«iivMii.,'Y.^^«jrv-
um, Araenic, Antimony.
CONTKNTS.
3. Test on Obaraoal, ..... 1
SulMtancea which may be detemuned by the Inartia-
n which they givB to the coal : Sfilenimn, Telluri-
am, Arsonic, Antimonj', Bismuth, Load, Citilmiiuii,
Zinc, Tin, Molybdenum, Silrer, Metallic Sulphidoa,
Chlorides, Broraidei and lodidoa.
4. Test in the Platinum Forceps, (oa well as, in some
oaaeB, on the platinnm wire or coal,) . . i
Bnbltances which may be detected by the Color which
they oommmucate to the blowpipe flame : Soda, Po-
toaaa, Cataia, Rubidiui, Lithja, Strontia, Lime, Baiytft,
Uolybdic Acid, Oxide of Copper, Telliirous Acid,
PboBphorio Acid, Boracic Acid, Thallium, Arsenic,
* Antimony, Lead, Indium, Seleninm, Chloride and
I Bromide of Copper.
5. Test in the Borax Bead, . . , . ■
S. Tost in the Phoaphorua Bead, . . . '
Substances which may bo dotermlnod especially by
the Colora which they impart to the Beads of Borax
and Salt of Phosphorus : Oxides of Cerium, Lantha-
num, Didymiiun. Manganese, Iron, Cobalt, Nickel,
Zinc, Cadmiom, Indium, Lead, Thallium, Tin, Bis-
muth, Uranium, Copper, Silver, Platinum, Falladiuin,
Bhodium, Iridium, Huthenium and Gold, Titanic, Co-
^lurobic, NioMc, Antimonioua, Tnngstic, Molybdic,
Vanadic, Chromic and TelluroDs Acids.
Ue I, in which the above BUbstancos are arranged accord-
ing to the Colors which they give the beads of Borax
and Salt of PhoepboroB, ....
Table II. On the Behavior of Metallic Glides when heated
alone upon Charcoal ; with Carbonate of Soda on Char-
n the Beads of Borax and Salt of Phospho-
nu on the Platln
a Wire,
fiblelll. On the Behavior of the AJialine Earths and
Earths Proper boforo the Blowpipe,
7. Teat with Soda, .....
Substances which, under certain circumstances, may
* be detected in this way : Silicic, Titanic, Tongftic and
Molybdic Acids, Gold, Silrer, Platinum, Tungsten,
Molybdenum, Antimony, Arsenic, Tellurium, Copper, •
Bismuth, Tin, Lead, Thallium, Zinc, Cadmium, Indi-
um, Kickel, Cobalt, Iron.
8. Special Tests for the determination of certain sub-
stances, ..«••• 71
These substances are: Potassa, Lithia, Boracic Add,
Sulphuric Acid and Sulphur, Kitric Acid, Fluorine,
Chloiine, (Chlorides and Chlorates), Bromine, (Bro-
mides and Bromates,) Iodine, (Iodides and lodates).
Magnesia^ Columbic Acid, Alumina, Oxides of Zinc,
Tin and Antimony, Titanic and Niobic Adds, Zirco-
nia. Oxide pf Magnesia, Tellurium, Arsenic, Phos-
phorus.
ABBREVIATIONS EMPLOYED IN TABLES II. AND III.
Bx. — ^Borax or Biborate of Soda.
Ch. — Charcoal.
Ct. — Coating or Incrustation.
OFl.— Oxidizing Flame.
BFL — ^Reducing Flame.
Sd. — Carbonate of Soda.
SPh. — Salt of Phosphorus or microcosmic salt, a phos*
phate of soda, ammonia and water, which when heated
loses its water and ammonia and becomes a monobasic
phosphate of soda.
CONTBHriS.
Tin
Alphabetical List of Certain Substances wbicli may be
Detected with the Aid of the Blowpipe.
Alninma, p 44, 66, 80.
Antimony, p 25, 27, 41, 44, 52,
71, 80.
Arsenic, p 25, 27, 41, 52, 71, 81.
Baryj», p 37, 44, 66.
Bismuth, p 28, 44, 62, 71.
Boracic Acid, p 40, 73.
Bromine, p 33, 79-
Cadmium, p 29, 44, 52.
Gnsium, p 35.
Cerium, p 45, 54.
CMorine, p 33, 78.
Fluorine, p. 75.
Glucina, p. 44, 68.
Chromium, p 45, 54.
Cobalt, p 45, 54, 71.
Columbic Acid, p 44, 80.
Copper, p 38, 42, 45, 54.
Didymium, p 45.
Fluorine, p 75.
Glucina, p 44, 68.
Gold, p 56, 70.
Indium, p 29, 42, 44, 56.
Iodine, p 33, 79.
Iron, p 45, 56, 71.
Lanthanum, p 44.
Lead, p 28, 42, 44, 56.
Lithia, p 32, 36, 72.
Magnesia, p 44, 66, 80.
Manganese, p 45, 56, 81.
Mercury, p 23, 58.
Molybdic Acid, p 30, 38, 44, 58.
Nickel, p 45, 65, 71
Niobic Acid, p 44, 81.
Nitric Acid, p 75.
Phosphoric Acid, p 39, 83.
Platinum, p 70.
Potassa, p 35, 72.
Rubidium, p 36.
Selenium, p 23, 25, 26, 42.
SiHca, p 44, 71, 74.
Silver, p 31, 44, 60.
Soda, p 34.
Strontia, p 36, 44, 66.
Sulphur, p 25, 31, 74.
Tellurium, p 23, 27, 39, 44, 60,
81.
ThaUium, p 29, 44, 44, 60.
Tin, p 30, 44, 60, 80.
Titanic Acid, p 44, 62, 80.
Vanadic Acid, p 45, 62.
Uranium, p 45, 62.
Yttria, p 44, 68.
Zinc, p 29, 44, 46, 80.
Zirconia, p 44, 68, 80.
Introduction,
The blowpipe is a simple instrument which has for
several centuries been used by workers of metals in
yarious countries to produce suddenly an intense heat.
Its use having been chiefly to melt the solder employed
in fastening together pieces of more infusible metals, it
is called by the Germans soldering pipe. The simplest
and most ancient form of the blowpipe is a hollow, coni-
cal, metallic tube, which at the small end is bent
without a sharp turn to a right angle. In using, the
larger end of this is taken into the mouth and a stream
of air blown into it, which is applied as it issues frona
the point exactly like the blast from a bellows. The
blowpipe may, therefore, be regarded as a small bellows
fed by the mouth, and its heatinp^ effect depends upon
the same principles. In this rude application and form
the blowpipe was of no importance to science. This it
came first to possess when the careful study of several
scientific men had converted it into one of the
most valuable instruments for the chemist oAidxs^XNi^t^^^
gist, as well as for nuners and me\a3\\a©aXa* ^"SV^ ^^
10 . INTRODUCTION.
lowing historical sketch shows how this was gradually
accomplished. *
Anthony Swab, a Swedish counselor of mines, who
lived in the first half of the eighteenth century, was, so
far as is known, the first who undertook to apply the
blowpipe to the chemical examination of ores and
minerals. Next to him, the Swedish mineralogist Cron-
stedt, used the blowpipe for determining and distinguish-
ing minerals, with special reference to the chemical sys-
tem of mineralogy published by him in 1758. Enges-
troem, who in the year 1765 translated this system into
English, added a description of Cronstedt's method of
using the blowpipe. In the year 1773 this description
was translated into Swedish, and soon after, into several
other European languages. Imperfect as the application
of the blowpipe then was, it attracted immediately great
attention from the rapidity and certainty of its results.
Nevertheless, the new art, which easy as it appeared
required long continued practice, made at first but little
progress. It received important assistance from the
efforts of Bergmann, who employed the blowpipe for
qualitative examinations in the whole province of inor-
ganic chemistry, and showed how by ita aid very mi-
" nute quantities of mineral substances could be detected,
the discovery of which in any other way would be much
more difficult. Bergmann published the results of his
experiments in a work, which was printed in Latin at
Vienna in 1779, and was translated into Swedish by
Hjelm in 1781. Upon the death of Bergmann, which
iappened aooa afierj (in 1784"), GaViu ^\xt^\i^ atiU
INTRODUCTION/ 11
further the path struck out by the latter. He attained
by persevering zeal to great skill in the use of the
blowpipe, without, however, recording anything of his
rich experience, which would have been for the most
part lost except for his obliging readiness to com-
tnunicate the art to any one desirous of acquiring
it. The young Berzelius, whom Gahn regarded
with peculiar interest as a student of science, was thus
enabled to possess himself of his knowledge, and upon
this foundation to build greater. Gahn had made a
good selection ; a person better adapted for this further
development of the art could scarcely have been found.
By him the application of the blowpipe was not only in
a high degree perfected and extended, but at the same
time by his personal instructions and writings so widely
diffused that it has now become an essential part
of the knowledge of every chemist and mineralogist.
In the year 1821 Berzelius published his excellent
'*Use of the Blowpipe in Chemistry and Mineralogy,^'
of which since that time seveml editions have appeared
and which has been translated for the use of American
students by Professor J. D. Whitney.
All the efforts of those who thus far had used the
blowpipe in chemical experimentation had been directed .
to qualitative analysis. Harkort, however, seizing upon
the fruitful idea of employing the blowpipe also in
quantitative analysis became the founder of a new branch
of the blowpipe art. In 1827 appeared as the result
of his experiments made in Frelbex^ W^ %x^\. \>l\«^'^'^
of hia ''Art of Assaying with tlie ISVowpv^'' ^Q^\\s&Kcci^
12 INTRODUCTION.
the article on silver. He was prevented from issuing
the second number, which was to contain the methods
of determining lead, copper and tin, by a call to Mexico,
where he died a few years after. Plattner, bis succes*
8or, perceiving the importance of developing the subject,
employed ]iimse1f for many years in applying to prac-
tice the idea of Harkort. His perseverance and in-
genuity enabled him to bring the art of assaying quanti-
tatively with the blowpipe to a degree of perfection
which had been previously thought impossible. Plattner
has given the results of his experiments both in qualita-
tive and quantitative assaying in his work, ^'Art of
Assaying with the Blowpipe," of which the first edition
appeared in 1835 and the second in, 1847, and which
has been translated and published in London.
The methods of assaying qualitatively and quantita-
tively with the blowpipe, in the state of perfection to
which they have been brought by Berzelius and Platt-
ner, are sciences so extensive that a considerable amount
of time and practice are required to become familiar with
them. Especially is this true of quantitative assaying,
which indeed is seldom acquired by chemists, but is
almost exclusively employed by practical metallurgists.
The following description of the apparatus, reagents
and methods to be employed in qualitative analysis with
the blowpipe, is believed to be sufficient for the use of
beginners, and even for most of the students in the
scientific schools and colleges of the country.
THE BLOWPIPE FLAME AND ARTICLES NECESSARY FOR
^ ASSAYING QUALITATIVELY WITH THE BLOWPIPE.
The blowpipe flame is produced when with the aid
of a blowpipe a current of air is driven in accordance
with certain rules through the flame of a candle or
lamp. The best flame for this purpose is that of an
oil lamp with a wide and rather thick wick. The prin-
cipal requisites to the production of a good flame are
first, the steadiness and sufficient durability of the blast;
and secondly, the proper application and management of
the same. The first will be treated of along with the
description of the blowpipe. In regard to the second
point, the flame may be made to produce upon the
heated substance etthef an oxidizing or a reducing
efiect.
The oxidizing and reducing flames are the principal
agents in the whole art of assaying with the blowpipe.
He who understands how to produce these flames of
the right kind and of sufficient permanence has over-
come one of its most difficult points.
To form a reducing flame, the point or jet of
the blowpipe is held parallel V\\\\ ^^ ^^xs^rt^^
14 BLOWPIPB FLAMES.
obliquely cut wick and in such a way that it just
touches the side of the flame. The result will be
a yellow, luminous flame.
An oxidizing flame is produced when the blowpipe
jet is introduced into the flame about one-third the
width of the wick. At the same time it is well to blow
a little harder than in the production of the reducing
flame. The oxidizing flame is of a blue color and
possesses but little illuminating power. *
The yellow color and luminous character of the re-
ducing flame result from the solid particles of carbon,
which unconsumed, but white-hot, float in the burning
gases till they are burnt upon the outside of the conical
flame. In the oxidizing flame, which exhibits the blue
color of burning carbonic oxide gas, these particles of
carbon are wanting.
It is not difficult to give the reason for the production
of these unlike flames. In the reducing flame the less
powerful blast from the blowpipe drives the whole flame
before it without causing a complete mixture of the com-
bustible gases with the air ; while in the oxidizing flame
a more powerful stream of air is thrown directly into
the flame, and is thus more thoroughly mixed with the
burning gases. In the latter ease, therefore, a much
more complete combustion must take place than in the
former.
If a piece of- a substance capable of oxidation be held
directly before the point of the oxidizing flame, it will
be heated by it, and will be oxidized by the surrounding
atmospheric air. If a powerful \Aaal \>e> \v&^^ m \!m
THE BLOWPIPE.* 15
■
operation, a portion of tho air will pass unconsumcd
through the point of the flame and increase its oxidiz-
ing effect. Not only is the oxidizing flame employed
for oxidation, but also, on account of the greater inten-
sity of its heat, for determining the fusibility of sub-
stances. It should here be observed that the point is
the hottest part of the flame.
The reducing flame has the greatest reducing effect
when the substance operated on is introduced so far into
the flame as to be completely surrounded by it and thus
protected from the oxidizing influences of the atmos-
pheric air. It must not, however, be introduced so far
into it as to allow it to become covered with carbon,
which would diminish the heat, and sometimes produce
other injurious effects.
A. — The Blowpipe.
The most convenient form of the blowpipe is that in-
vented by Berzelius. It consists of five parts, which
are so fitted together that they can be readily taken
apart for cleansing or transportation. These parts are a
mouthpiece, a narrow tube seven to nine inches long, an
air-chamber to collect the condensed vapor of the breath,
a small tube inserted into the air-chamber at right-angles
to the larger one, and a jet with a minute orifice for the
escape of tlie blast.
The mouthpiece may be either funnel-shaped to press
against the lips, in which case it is made of horn, or a
mere extension of the larger tube, foTmeA.oi\iW^a^Vi^t^
or silver, the tube itself being uauaWy o^ \>t^'&.
16 ' SUPPORTS FOR ASSAY.
The jet sboold bo a conical piece of platinum pro-
pyl/ boreal and drilled to fit the tip of the shorter tube
«lld to allow the escape of a very small straam of air.
Cttfcr mtMi be taken that the orifice be not too much en-
krg^d in removing the carbon which may collect upon
ilMl ohitruct it. This is best done by heating the jet to
With suflicicnt practice it is possible by osing the
wldo mouthpiece to blow uninterruptedly fi:om five to
im minutes. During this continuous blowing the ex-
p^imenter must breathe through the nose, using the
ptihte tm a valvo^ and force the air out by means of the
mtm\^ of the cheeks.
B. — Tub Blowpipe Flame.
The ftamo for use with the blowpipe may be that of
eoal gflS) a catidle, or a lamp filled with oil, burning
flttiil or alcohol. Where gas cannot be had, it will be
iimnd convenient to have both an alcohol and an oil
lamp. These may be either of glass or metal.
0. — Supports and Holders for the Substances
TO BE Heated.
For holding the substances which are to be exposed
to the flame of the blowpipe must be employed, of
course, materials which are not easily injured by heat.
The following articles are most commonly used : —
1. Charcoal. — ^The best for this purpose is a well
burnt^ compact and dry coal of pine or other soft wood.
CHARCOAL. 17
free from knots, and having the rings of growth as close
together as possible. Its good quality may be known by
its clear, ringing sound when struck. This should be
sawed into parallelepipeds six inches in length and two
ki width in such a way that the rings of growth are
cut oflF at right-angles to two of the long sides. These
sides of the coal are the ones for use. The substance to
be heated is laid near the edge of the coal, sometimes in
a shallow depression made in it. The other two long
sides of the coal, which run parallel with the rings of
growth or rather with tangents to these, are unfit for
use, since in consequence of their heterogeneous struc-
ture they often burn with very uneven surfiwes
and sometimes snap off. A substance is heated upon
coal when it is intended to reduce it, to prevent its oxid-
ation, or when the unavoidable reducing efiect of contact
with coal can exert no injurious influence upon the de-
sired result.
2. Platinum Wire, about 0.4 of a millimeter in thick-
ness. A long piece of this is bent several times around
in the form of a ring and the free ends bent up in-
to small hooks. The ring is held upon the index
finger of the left hand, and one of the hooks, filled
with the substance to be examined, exposes! to the flame
of the blowpipe. Borax, or salt of phosphorus, is com-
monly melted first to a transparent bead upon the hook,
and then the substance to be tested, in the form of small
peces or as a fine powder, heated with it, in order to
observe its reaction with these fluxes both in the oxi-
dating and in the reducing flame. 01 liWiX^^ ^"w.^
18 PLATINUM AND GLASS.
mast be taken not to treat in this T\raj metals or other
substances which under such circumstances would at-
tack the platinum wire.
3. Platinum Foil. — This is used for fusing sub-
stances which must not be subjected to any reducing
influence, as is unavoidable upon coal. The platinum
foil, which should be about 2 inches long and 1 inch
wide, may be laid upon a piece of charcoal or held in
forceps.
4. A Platinum Spoon, about half an inch • wide.
While in use the handle may be fastened to a' holder
made for the purpose and furnished with a screw for
securing it, or may be stuck into a cork. Such a spoon
is used for melting certain substances with bisulphate wr
nitrate of potassa.
5. Forceps, with platinum points. Their form is
such that the two platinum points are separated by
pressing upon the heads of rivets. Between the extremi-
ties of the platinum points is introduced a fragment of
the substance to be tested before the blowpipe either
with reference to its fusibility or the color which when
heated it imparts to the blue flame. The whole forceps
are from 5 to 6 inches long.
6. Glass Tubes, about 6 millimeters in diameter, and
from 5 to 6 inches long. These are employed chiefly
for roasting substances containing sulphur, arsenic,
selenium, tellurium or antimony, which when heated
with certain precautions in an open tube cither deposit
various sublimates upon the inner surface of it or give
off an odor by which they may be recognized.
BLOWPIPE REAGENTS. 19
7. Glass Mattrasses, which cau be easily made by
fosing together one end of a glass tube. Their length
should be about 8 inches. Thpy are used in heating
substances which contain volatile ingredients to protect
them as much as possible frotn the influence of the air.
The volatile substance driven oflF is deposited, in this
case, upon the inner surface of the tube, but not in an
oxidized condition as when heated in an open tube.
D.— The Blowpipe Reagents.
*
In most blowpipe experiments the number of reagents
employed is very limited and the quantity of these re-
quired very small. There are only three reagents
which can be said to be extensively used.
1. Soda. — Anhydrous carbonate of soda, which for
certain purposes must be free from sulphuric acid.
Soda is used principally to assist in the reduction of
metallic oxides and sulphides upon charcoal, to decom-
pose silicates and to determine the solubility or insolu-
bility of a substance when melted with it.
2. Borax. — Purified borax freed by heai from the
greater part of its water of crystallization and pulver-
ized. In using it, the red-hot hook of the platinum
wire is dipped into the powder and the portion adhering
to it melted in the flame of the blowpipe, and this ope-
ration is repeated till the bend of the wire is filled with
a globule which both hot and cold must appear per-
fectly transparent and colorless. The still soft bead of
borax is then dipped into the powder of the substance
to be tested, so that a suitable quantity of the same ad-
r
SPECIAL REAGENTS.
I
heres to it, which can then lie subjected to tho influenoo
of the melted borax glass iii tlio flame of the blowpipe.
The solubility or insolubility of the assay ia to be ob-
Berved, and also the color of the bead in the oxidizing and
in the reducing flame both while hot sind after cooling.
3. Salt of Phosphorus, the well known double phos-
phate of soda and ammonia. It cannot be meltud to a
bead directly upon the platinum wire without difficulty,
(since, so long as ammonia and water are disengaged, it
drops off easily), and must, therefore, first be freed
from these by heating gradually upon charcoal, and thea
taken upon the wire. Tho use is exactly like thut of
borax.
Besides these principal reagents, a few others are, in
certain cases, employed, viz : Faltpeter, for oxidizing
melted substances. Bisulphate of Fotassa, for cspciling
and determining certain volatile substances, (1itbi&,
boracic acid, nitric acid, hydrochloric acid, bromine,
iodine), as well as for the decomposition of titanates,
tantalates and tungstates. Nitrate of Cobalt, chemi-
cally pure and in solution, especially for tcaling for
alumina, magnesia, oxide of zinc, oxide of tin, and
titanic acid, which moistened with the solution of cobalt
and heated assume certain eharacteristic colors. Silica,
for various purposes. Fluor-spar, mixed with a certain
quantity of bisulpjiato of potassa, for detecting lithia
and boracic acid. Oxide or Oxalate of Nickel, for de-
termining the presence of a largo (quantity of potassa
in salts containing at the same time soda and lithia.
;Oxide of Copper, for detecting chlorine, bromine and
BLOWPIPE IMPLEMENTS. 21
iodine. Tin, in the shape of foil, for asBisting in Hip
redaction of substances dissolved in borax, or salt of
phosphorus. The hot bead, resting upon charcoal, is to
be touched with tin foil, so that a portion of this remains
upon it, and then heated a few seconds in as powerful a
reducing flame as possible. Silver, for detecting sulphur
and sulphuric acid.
The blowpipe reagents may be best kept in bottles,
well stopped with ground glass stoppers, — which may
be packed in a wooden box constructed for the purpose.
In traveling, means should be adopted 16 prevent the
stoppers from becoming loose and falling out.
*.
E. — Other Articles necessary in assaying with
THE blowpipe.
The method of using these articles, of which some are
rather convenient than indispensable, requires no ex-
planation. The following are, therefore, merely men-
tioned : a hammer, a small anvil, a steel mortar, an
agate mortar, files of various sorts, a knife, scissors, a
magnet, a microscope, &c,, &c.
II.
QUALITATIVE EXAMINATION WITH THE BLOWPIPE.
This consists of the performance of certain operations,
and the accurate observation of the resulting phenomena,
from which the presence or absence of certain substances
may be known. These operations may be undertakeii
most advantageously in the following order, viz : Test
of the substance to be examined, first, in a glass matrass,
i. e. in a glass tube closed at one end ; second, in a glass
tubo open at both ends ; third, on charcoal ; fourth, in
the platinum forceps ; fifth, in the borax bead ; sixth,
in the phosphorus bead ; seventh, with soda. After these
tests, it is often necessary to make some experiments for
the detection of certain substances, the presence or
absence of which could not be positively determined by
the preceding operations.
1. — Test in Glass Matrass.
The clean and perfectly dry matrass, containing a
small quantity of the substance to be examined, is heated
at the lower end at first gently over the flame of a
spirit lamp, and then gradually more intensely before the
blowpipe, till the glass begins lo soft^ia..
TEST IN GLASS MATIUSS. 23
It is to be noticed whether anything is sublimed or vol-*
utilized, as ex. gr. water, quicksilver, sulphur, selenium,
tellurium, arsenic. The first three may be readily recog-
nized from their well known properties. In case water is
sublimed, it should always be noticed whether it gives an
acid or alkaline reaction with litmus paper. When organic
substances are present, the fluid deposited on the walls
of the tube has a characteristic burnt taste and odor. A
microscope is often necessary to detect a small sublimate
of quicksilver ; its use should indeed rarejy be dispensed
with in these operations. Selenium gives a red sublL
mate ; if a large quantity be present so that a thick crust
is deposited, the color in the lower part of the tube is
steel-gray. Tellurium produces a gray sublimate. Ar-
senic yields a black deposit, which, when the quantity is
considerable, has a somewhat metallic luster. It must
not, however, be concluded, because these reactions do
not appear, that these elements are not present, since
sulphur, selenium, tellurium and arsenic especially
may occur in compounds from which they either can
not be liberated by such ignition, or at least not in a
pure condition. It is also to be observed that two or
more of them may be present in a compound and may
be sublimed together, by which the difficulty of recogniz-
ing them is more or less increased. This is very often
the case with sulphur and arsenic. These sometimes
give a sublimate, which below consists of metallic arsenic,
but higher up appears successively black, brown, red
and yellow ; colors due to sulphide oi 3bT^^\\\ft^\x\i\0ft.\^
more volatile than the metal. Oxygpu ^"cA ^\!Kal^\v\^^
24 TEST IN GLASS MATRASS.
when disengaged from a substance bj heat, may also be
detected in the matrass; the first, by introducing a
burning splinter of wood ; the last, by the introduction
of a strip of reddened Utmus .paper. Commonly, how-
ever, ammonia is not given off in a pure state but com-
bined with an acid, and then p. white sublimate of an
ammoniacal salt is deposited. By mixing the assay wiA
lime or soda, and then heating it in a mattrass, free ani-
monia is liberated and easily recognized. Some other
substances, especially fluorine, chlorine, bromine, iodine
and nitric acid, can be detected in the matrass ; since
this, however, cannot in most cases be done by heating
the substance under examination alone, but only by the
use of some particular reagent, the method will be giv^
in the eighth section, which treats of the performance of
special experiments for the detection of certain sub-
stances.
. It is to be observed, secondly, whether the substance
heated is in any way altered, ex. gr. changes its color and.
perhaps in cooling resumes it, varies its form or state of
aggregation, exhibits a flash of light or phosphorescence,
decrepitates, &c., &c. To treat in a special manner all
such cases hero would occupy much space, and still not
obviate the necessity of more exact chemical knowledge,
which the skillful experimenter with the blowpipe must
always have at command.
The test in the matrass gives in many cases, as appears
from the preceding, no distinct proof, but often only in-
dications of the presence of substances whicli can be
determined with absolute certamty ovA^ «&.^t «t\ll further
TEST IN THE OPEN TUBE. 25
Bxperimentation. The indications are nevertheless of
Importance, and afford much assistance towards the fin^l
lecision.
2. — Test in the Open Tube.
A portion of the assay finely pulverized is introduced
ibout a half an inch into tlie tube, and this gradually
heated at the place where the substance lies.. The tube
should be held a little inclined, so that the current of
heated air passes over the assay, and upwards through the
upper and longer part. In this way the assay is roasted,
i. e. exposed to an oxidizing heat, by which Various sub-
stances are volatilized and rendered recognizable. Sul-
phur is disengaged as sulphurous acid, which may be
easily known by its peculiar suffocating odor. Selenium
is but little oxidized, and deposits a red or steel-gray
Bublimate, at the same time giving the very characteris-
tie odor of selenium vapor — resembling that of decayed
horseradish — ^a ready and sure proof of its presence.
Arsenic is volatilized as arsenious acid, antimony, as oxide
of antimony and tellurium as tellurous acid, all of which
form a white sublimate. That of arsenious acid is dis-
tinctly ,-crystalliue, while the others appear pulverulent.
Arsenious acid and oxide of antimony can be driven for-
ward by heat from the place where they have been
deposited, but in the case of tellurous acid, this takes
place only in appearance, since it fuses to small trans-
parent drops, which may be detected sometimes by the
naked eye, though better with the aid of a microscope.
The roasting process must be cameA. ow ^v^Vj ^^ii^
26 TEST ON CHARCOAL.
a gradually increa^^ing temperature and a good current
•fair, produced by the inclination of the tube; since
otherwise, unoxidiz..'d volatile substances might be
sublimed, and the assay fused together so as to prevent
further oxidation. To roast a substance as completely as
possible, it is necessary after heating it some minutes, to
grind it in an agate mortar, and then to repeat the
roasting. This alternate heating and grinding must be
continued till nothing more is sublimed.
3 — Test on Charcoal.
The same things are to be observed in beating on char-
coal as in using the matrass. Especially important is it
to become familiar with the color and certain other pro-
perties of the incrustations which different substances
deposit when heated on charcoal. These are more par-
ticularly treated of in the following synopisis taken from
Plattner's "Art of Assaying with the Blowpipe."
Selenium melts easily, and gives in the oxidizing
or reducing flame brown fumes, and deposits an incrus-
tation which at a little distance from the assay is steel-
gray, with a slight metallic luster, and at a greater
distance, dull and dark-gray, inclining to violet This
incrustation is readily driven from one place to another
by the oxidizing flame, but, if touched with the reducing
flame, vani.^hes, coloring the flame at the moment beauti-
ful ult;ramarine. When selenium fused on coal ,or a
deposit from it, is touched with the blowpipe flame a
strong odor of decayed horseradish is perceptible, dae
TEST ON CHARCOAL. 27
to the gaseous, colorless oxide of selenium which is
thus produced.
Tellurium melts very easily, gives oflf fumes and
deposits on the coal, not far from the assay, both in the
oxidizing and in the reducing flame, teUurous acid. The
deposit is white, with red or dark-yellow edges, and may
be driven from place to place by the oxidizing flame, but
in the reducing flame vanishes, coloring the flame at
the same time green, or, when selenium is present, bluish-
green.
Arsenic volatilizes without fusing, and deposits upon
the coal, in the reducing as well as in the oxidizing
flame, arsenious acid. The deposit is white, in thin lay-
ers, grayish, and at some distance from the place where
the assay was laid. It is removed instantly when
merely warmed by the blowpipe flame. If heated sud-
denly in the reducing flame, it vanishes, giving the flame
a feeble light-blue color. When volatilized it gives a
strong alliaceous odor, which is peculiar to the suboxide
of arsenic.
Antimony fuses readily, and incrusts the coal with
oxide in both flames. The incrustation is white, in
thin layers, bluish, and nearer the assay than that of
arsenious acid. By a gentle heat from the oxidizing
flame, it may be driven from one place to another with-
out coloring the flame, but, if exposed to the reducing
flame it changes its positions with a slight greenish-
blue color. The oxide of antimony being much less
28 TBST ON CHARCOAL.
volatile than the arsenioiis acid may be easily distin-
guished from it If metallic antimony be melted on
charcoal and heated to redness, and then allowed to re-
main undisturbed, it continues a long time red-hot, and
gives off dense white fumes, which are partly deposited '
upon the coal, and partly around the globule of metal
in white, pearly crystals. Tliis phenomenon depends on
the fiict that the red-hot fluid globule of metal absorbs
oxygen from the air, oxide of antimony is formed, and
thus so much heat liberated as is necessary to keep the
very fusible antimony in a melted state for some time,
till it becomes covered with crystals of the oxide.
Bismuth fuses very easily, and deposits on the coal
oxide of bismuth, both in the oxidizing and in the re-
ducing flame. The deposit is, while hot, dark orange-
yellow, when cold, lemon-yellow, and in thin layers,
bluish- white. The yellow deposit consists of pure oxide
of bismuth, and the bluish-white, which is farthest from
the assay, of carbonate of bismuth. The bismuth in-
crustation is deposited a little nearer the assay than that
of antimony. It may be driven from place to place by
either flame, since the oxide is reduced on the coal at a
red heat, and the metallic bismuth then volatilized and
reoxidized, but does not, when heated in the reducing
flame, impart to it any color.
Lead melts easily, and gives the coal in either flame
an incrustation of oxide at the same distance from the
assay as that of bismuth. The deposit while hot, is
dark lemon-yellow, after cooling, sulphur-yellow, and in
TEST ON CHARCOAL. 29
thin layers, bluish-white. The yellow crust is pure
oxide of lead, and the bluish-white, carbonate of lead.
The yellow deposit when heated in the oxidizing flame
changes its place for the same reason as the oxide of
bismuth, and without coloring the flaine ; in the reduc-
ing flame it changes its position, tinting the flame with
ultramarine.
Thallium melts, volatilizes and deposits a brown in-
crustation, coloring either flame a brilliant green.
Cadmium melts readily, takes fire in the oxidizing
flame, bums with a dark-yellow flame and brown fumes,
and deposits on the coal near the assay oxide of cad-
mium. This exhibits its peculiar color best when com-
pletely cold; it is reddish-brown, in thin layers, orange-
yellow. The deposit of oxide of cadimum may, since
the oxide is easily reduced, be volatilized by either flame,
but without imparting to it any color. Around the outer
edge of the incrustation the coal sometimes exhibits pa-
Yonian tints.
Indium fuses readily, forms in the oxidizing flame a coat-
ing brown while hot, and yellow when cold, and which
touched with the reducing flame colors it blue.
Zinc fuses easily, takes fire in the oxidizing flame,
burns with a very luminous, greenish-white flame and
dense white fumes, and gives the coal an incrustation of
oxide. This is rather near the assay ; while warm, yel-
low, and when completely cold, white. He».taii yol ^S^fe
80 TEST ON CDARCOAL.
oxidizing flame it glows, but is not volatilized because it
cannot bo reduced by the heated coal on which it rests.
Even in the reducing flame it is volatilized but slowly.
Tin melts without difficulty, and in the oxidizing flame
becomes covered with oxide, which may be remov^ by a
puff of air ; in the reducing flame the fused metal pre-
sents a brilliant surface and inerusts the coal with oxide.
The incrustation is while hot, slightly yellow, and some-
what luminous in the oxidizing flame ; but, upon cooling,
it become3 white. It is so near the assay as to touch it
on all sides. It cannot be volatilized.
Molybdenum, in metallic form, cannot be fused
before the blowpipe, but when heated in the exterior
flame gradually oxidizes, and covers the coal, at a little
distance from the assay, with molybdic acid, which is
deposited in some places, especially nearest the assay, in
transparent, crystalline scales, but elsewhere in a pulveru-
lent form. The deposit has while hot, a yellowish color,
but on cooling becomes white. The crystalline scales
are best produced, by heating the assay as far as possible
from the point of the blue flame. The pulverulent mo-
lybdic acid can be driven about by either flame, but the
place which it leaves appears, after it is completely cold,
dark copper red and has a metallic luster, from oxide
of molybdenum, which is formed by the reducing effect
of the coal on the acid, and which is not volatile. In
the reducing flame, metallic molybdenum remains un-
changed.
TEST OK CHARCOAL. 81
Silver, held for sometime in a fluid condition by a pow-
erfal oxidizing flame, gives a very slight deposit of dark
red oxide. In combination \?ith a small quantity of lead,
there appears, first, a yellow deposit of oxide of lead, but
afterwards, when the silver contains less lead, it colors
the coal outside the yellow crust dark red. If the
silver contain a little antimony, there appears, first, a
white incrustation of oxide of antimony, which, if the
blowing be continued, becomes red. An alloy of silver,
lead and antimony gives, after the latter metals are mostly
volatilize^, a copious, carmine red deposit. Such a
deposit may also sometimes be obtained by heating alone
on charcoal a rich ore of silver.
Sulphides, Chlorides, Bromides, and Iodides of
THE Metals. — In assaying with the blowpipe, not only
are pure metals found, which being somewhat volatile, may
be detected by the incrustation which they give the coal
when sublimed, but there are also compounds which
deposit a white crust upon the coal, that may be driven
oflF by the oxidating flame, and very often resembles
closely a deposit of oxide of antimony. Here belong of
the sulphides, those of potassium and sodium, which
while forming from the sulphates in the reducing flame
on coal, yield a white, and not very volatile incrustation
of sulphates, produced by the reoxidation of the volatil-
ized sulphides. This, however, does not occur till the
sulphates have sunk into the coal, and given off their
oxygen. Sulphides of potassium being more volatile
than sulphides of sodium, the former are deposited earlier,
and in greater quantity than the latter. Tl\v& da^os^t*^
^■8 TEST ON CHARCOAL.
when touched 1>y the reducing flame, disappears, impat
ing to the flame, when conaisdng of sulphate of pot
a. bluish violet color, and, wlien of sulphate of soda,
reddish yellow. Sulphide of lithium, formed by tl
raductiou of sulphate of litliia on coal, is also voIatiUi
by an intense heat, but more difficultly thau sulpUidi
sodium, and gives, instead of a pure white, a greenish
white, thin crust, which toucbod with the rejuciag flame
vanishes, coloring tbe flamo caimiue red. Tlie suIphideH
of lead and bismuth also belong here. Each of these
Bulpbido!^, both in the oxidizing and the reducing flame,
aflbrds two different deposits of which the most volatile
is white, and is a sulphate, When these deposits are
heated in tbe reducing flame, that of lead disappears,
communicating a blue tinge to the flame; that
bismuth vanishes, but does not color tbe flame,
incrustation nairest tbe assay consists of the oxide of
metal, and may be recognized from its color, both whil
hot and after cooling. There are indeed several other
sutpbidos of metals which incrust the coal, when thor-
ougldy heated before the blowpipe, with a more or less
abundant white deposit, ex. gr. sulphide of antimony,
sulphide of zinc and sulphide of tin; but tbe deposit
consista only of the oxides, and is in the oxydating fli
cither volatile or fixed.
Among the chlorides of the metals, several possess
property, when heated before the blowpipe on coal,
volatilizing and depositing a white incrustation,
I the chlorides of potassium, sodium and lithium,
ibiking into the coal in a Suid state, volatilize and ^i
^rs,
'hile
TEST ON CHARCOAL. 38
a white deposit near the assay, (chloride of potassium
yields the most ahundant, and chloride of lithium the
least, which also instead of being pure white, is grayish) ;
chlorides of ammonium, quicksilver and antimony,
which volatilize without melting; chlorides of zinc,
cadmium, lead, bismuth and tin, which first melt and
then afford two incrustations, viz : a white, volatile one
of chloride, and a less volatile one of oxide. These in
the reducing flame disappear, a part of them with a col-
ored flame. That of chloride of potassium is bluish, in-
clining to violet, and that of chloride of sodium, reddish-
yellow, of chloride of lithium, carmine red, and that of
chloride of lead, blue ; the remainder do not color the
flime. Chloride of copper fuses and colors the flame
intense ultramarine. If the blowing be long continued,
it may be observed that one part of the assay is volatil-
ized with white fumes Laving a strong odor of chlo-
rine, and another deposits on the coal three rings of .
different colors, of which the one nearest the assay is
dark-gray, the next dark-yellow to brown, and the third
bluish-white. In -the reducing flame a portion of these
may be made to change position, coloring the flame at
the same time ultramarine.
Of the bromides and iodides of n^etals which appear
on coal very similar to the chlorides, should be particu-
larly noticed here the bromides and iodides of potassium
and sodium. These melt and are absorbed by the coal,
and are then volatilized with white fumes, a part of
which forms at some distance from the assay a. ^Vl\*a
crust on tlu charcoal. This w\ieii\.OMdi\^^^iJ0oL*^^'t5^
34 TEST IN FORCEPS.
ducing flame disappears, the bromide and iodide of po-
tassium coloring the flame bluish, inclining to violet, and
bromide and iodide of sodium, reddish-yellow.
4. — Test in the Platinum Forceps.
It having been settled by previous experiments that
the assay does not when heated attack platinum, a small
fragment or splinter is taken in the forceps and exposed
to the point of the exterior flame. Substances which
attack platinum may be heated on coal, or, if easily fusi-
ble, on the platinum wire. The object is not' only to
determine the fusibility of the assay, but also the pres-
ence of certain substances which under these circum-
stances impart more or less distinctly a color to the blue
flame of the blowpipe. Some substances impart a yel-
low, others a violet, carmine red, green, or blue color.
Plattner, in his work previously quoted, gives on this
subject the following particulars :
Yellow. — Soda and its salts, when fused on the plat-
inum wire in the point of the blue flame, possess the
property of increasing the size of the exterior flame,
and coloring it intense reddish-yellow. This reaction is
not prevented by the presence of a large quantity of
other salts, whose bases also color the exterior flame,
though not so intensely as. soda. For the appearance on
coal, see page 82. If a small splinter of a silicate con-
taining soda be ignitt-d or fused in the point of the blue
Bame, it increases more or less the ouier flame, according
^ it is more or less fusible and. coTi\aAna xaot^ QtVjeBi
TEST IN FORCEPS. 35
soda, tinging it at the same time reddish-yellow. If
the blowing be long continued, this color remains un-
changed, or becomes more intense.
Violet. — Potassa, Csesia and Rubidia, and most of
their salts, except^ the borate and phosphate, when
fused in the point of the blue flame, color the exterior
flame distinctly violet. If, however, the salt be mixed
with only a very minute quantity of a salt of soda, the
reaction is so changed that while near the assay a slight
violet tinge may be perceived, further from it appears
the intense reddish-yellow of the soda. If the mixture
contain several per cent, of a [salt of soda, the reac-
tion of potassa is wholly suppressed, and only that of
soda can be perceived. The reaction of potassa is also
prevented by the presencejof a small quantity of a salt
of lithia. For the appearance of some salts of lithia on
coal, see page 32.
Many minerals containing lithia and fusible in the
point of the blue flame communicate a red color to the
exterior, flame. This is especially true of the micas from
AJtenberg and Zinnwald, which color the outer flame
very strongly ; this color diminishes, however, in inten-
sity, as soon as the thin strip is melted to such an extent
that it can no longer^ be kept perfectly fluid in the flame
of the blowpipe. There are also minerals which give
along with the red of lithia still another color, and in
such a manner that both appear either separate or
mixed. If, for instance, a minute quaivtit^ q^ y^'^^"^'^'*^
triphjrllne, (phosphate of lithia, iron axAxwi^xi^^^^J^i
36 TEST IN FORCBPS.
fused on the platinum i^ire in the blue flame, there
appears in the outer flame a carmine-red streak from
lithia, surrounded by a green flame resulting from the
phosphoric acid. In the forceps this is difficult to
observe because the triphyline is too easily fused. K a
small piece of amblygoniie from Cursdorf, which consists
chiefly of phosphates of lithia and alumina, be fused in
the forceps in the point of the blue flame, there appears
in the exterior flame a yellowish-red streak, which is
surrounded by a reddish-yellow flame resulting from the
presence of soda. This color continues as long as a
portion of the assay is kept in a fluid state.
Silicates containing lithia, which alone impart no red
tinge to the exterior flame, do so, according to Turner,
when melted with fluor-spar and bisulphate of potassa
on the platinum wire in the point of the bli^e flame, as
will te explained in section 8.
Strontia. — Chloride of strontium fused on the pla-
tinum wire in the point of the blue flame produces in-
stantly an intense red color in the outer flame.
Many other salts of strontia, ex. gr. carbonate of
strontia, (strontianite), and sulphate of strontia, (coeles-
tine), when exposed to the point of the blue flame in
the forceps color the outer flame at first slightly yellow-
ish, but afterwards carmine-red. The presence of baryta
prevents the reaction of strontia.
Limb. — Chloride of calcium tinges the exterior flame
red, though not so intensely as chloride of strontium.
Most pare calcites as well as maasivvfe eaxVyosl^^ of lime
TEST IK FORCEPS. 87
produce at first a feeble yellowish color in the exterior
flame, but afterwards when the carbonic acid is driven
otE, a red, which is, however, less intense than that from
strontia. The presence of baryta prevents the reac-
tion of lime. Fluor spar, while fusing, colors the
outer flame as deep red as calc-spar. Gypsum and
anhydrite produce at first only a feeble yellowish tinge,
but afterwards a rather intense red. Phosphate and
borate of lime do not give a red, but a green color.
Of the silicates, none afford the reaction of lime ex-,
cept table-spar, which imparts to the exterior flame a
slight reddish tinge.
Green. — There are seven substances which color the
exterior flame green, viz : baryta, moIyBdic acid, oxide
of copper, tellurous acid, phosphoric acid, boracic acid
and thallium.
Baryta. — Chloride of barium when fused on the pla-
tinum wire produces in the exterior flame a green color
which at first appears only light-green, but afterwards
becomes an intense yellowish-green. The color is most
beautiful when only a very small quantity of the salt is
used. Carbonate of baryta, (witherite), and sulphate of
baryta, (heavy spar), when held in the forceps and
strongly heated in the point of the blue flame also tinge
the exterior flame yellowish-green, though not so deeply
as chloride of barium. The presence of like does
not prevent the reaction of baryta. For instance,
baryto-calcite, consisting of carbouates of lime and
baryta, causes in the exterior a gceenidcL-^^^^'^ ^^^x\
88 TEST IN FORCEPS.
if, however, the blowing be long continued, it may be
perceived that the point of the flame is also sometimes of
a reddish tinge. '
MoLYBDic Acid. — Molybdic acid, or oxide of molyb-
denum, when attached to the moistened platinum wire
and ignited in the blue flame, colors the exterior flame
bluisli-grcen, exactly like baiyta, molybdic acid at the
same time volatilizing. If a thin scale of natural sul-
phide of molybdenum be held by the platinum forceps
in the point of the blue flame, it does not fuse, but im-
mediately imparts to the outer flame a yellowish-green
tinge, resulting from the molybdic acid formed by its
oxidization.
Oxide of Copper. — Oxide of copper, alone as well
as in combination with certain acids which do not them-
selves give a colored flame, for instance, with carbonic,
acetic, nitric and sulphuric acids, communicates to the
exterior flame an emerald-green color. Metallic cop-
per, when heated on real in the flame of the blowpipe,
is easily oxidized, and then tinges the outer flame emer-
ald-green. The iodide of coppor causes also a very in-
tense emerald-green color in the exterior flame. Ores of
lead containing copper color the outer flame in the cen-
ter blue from the lead, (see below), and upon the out-
side, especially near the point, emerald-green. Sili-
cates containing copper, when heated in the forceps with
the point of the blue flame, sometimes impart to the exte-
rior flame a very intense emerald-green color, ex. gr.
dJqptase, and chrysocoUa.
TEST IN FORCEPS. 39
This color is also produced by those in which the oxide
of copper constitates an unessential, and only the col-
oring part of the mineral, ex. gr. turquoise.
Tellurous Acid. — ^Tcllurous acid, suspended on the
moistened platinum wire, and heated ii^the point of the
blue flame, melts, gives oflF fumes and colors the exterior
flame green. If the tellurous acid, deposited on coal
firom heating an ore of tellurium, be touched with the
point of the blue flame, it vanishes with a green, or
when selenium is present, with a bluish green flame.
Phosphoric Acid. — According to Fuclis and Erd-
mann, phosphoric acid, phosphates and minerals contain-
ing phosphoric acid, sometimes alone, and sometimes
after being pulverized and moistened with sulphuric acid,
impart to the exterior flame a bluish green color. This
reaction is so reliable that with suitable care very minute
quantities of phosphoric acid may be detected in miner-
als, when a little of the paste, formed by moistening
the powder of the mineral with sulphuric acid, is taken
on the platinum wire and exposed to the point of the
blue flame. The same is true also of compounds, which
from containing a large admixture of soda or other in-
tensely coloring substance, do not alone give the reac-
tion of phosphoric acid. If the salt contain water,
it must first be driven off by heating on coal before the
blowpipe, and then the anhydrous substance pulverized,
moistened with sulphuric acid, and exposed to the blue
flame on the platinum wire. If soda be present, the
outer flame is tinged very distinctly \A\i\stiL gc^^xi^\.*Oc!kfe
■r
moment tbe phosphoric acid is liberated by tho action of
the sulphuric acid, but afterwards assumes ttio intense
reddish yellow of the soda. As the bluish greon lasts
in aomo cases but a short time, it must be observed
whether tlie outer flame is colored bluish greon or not, at
tlio instant the assay is touched with the point of the
blue flame. Phosphate of lead iis well as pyromorphite,
heated alone, tiiigos the eilgos of the blue flame of oxide
of lead with a permanent greeji,
BoRACic Acid. — Both natural and artificial boracio.
■ ftcid, when molted on the platinum wire ia tbc point
of the blue flame, impart to it a deep yellowish greon,
(siskiD-gieen.) If, however, ihe acid be not perfectly free
from soda, there results in the outer flame a green color,
■which is more or less mixed with yelbw. Borax alone
produces no green, but only t!ie yellow of soda. Anhy-
drous borax, however, when pulveriaed and mnistencd
■with sulphuric acid, and exposed to the point of tho VjIuo
flame, gives for a short time an intense green, which
changes to yellow as soon as tho salt is decomposed anit
the free snlphuric acid o.tpelled. Minerala containing
boracic acid, when heated on the platinum wire with
the point of tho blue flame, after being pulverised and
moistened with sulphuric acid, almost all communi-
cate to tho exterior flume a green calor, Anotlior and
I very reliable method of detecting boracic acid in miner-
■1b from the .liskin green color of the outer flamo baa
been proposed by Turner, and will be found in section 8.
Thallium. — Substances conlamti^ v\\Ti\\\wm,
:lioQ S;
J
TEST IK FORCEPS. 41
Strongly heated, color the flame bright green, which is
changed to yellow and thus obscured by the presence of
much soda.
Blue. — ^There are some substances which when igni-
ted or fused in the inner flame, color the exterior flame
blue, viz: arsenic, antimony, lead, indium, selenium
and compounds of copper with chlorine and iodine.
Arsenic. — ^Metallic arsenic and the arsenides of
those metals which do not communicate any color to
the exterior flame, as ex. gr. copper-nickel, cobaltine,
Ac, &c., when heated by the blue flame on coal, are
surrounded by a blaze of a light blue color. If the
incrustation of arsenious acid deposited on the charcoal
be touched suddenly by the blue flame, it being very
Yoktile may be clistinctly observed to disappear with the
same light blue blaze. When arseniates whose bases
impart no color to the exterior flame, as ex. gr. nickel
bloom, cobalt bloom, iron sinter, &c,, are exposed in
tiiQ forceps to the blue flame, they communicate an in-
tense light blue to the outer flame. In many cases a
blue color appears even when the base possesses the
prc^rty of coloring the flame, as ex. gr. arseniate of
lime, (pliarmacolite.)
AktihoNT.' When metallic antimony is fused within
the blue flame on charcoal, the fluid globule of metal is
surrounded by a scarcely perceptible blue blaze ; but,
if the resulting white crust of oxide of antimony be
touched with the blue flame of the blowpipe, it disap-
pears iingiDg the flame greenish blue.
42 TEST IN THB BORAX BEAD.
Lead. — ^When metallic lead is melted on coal within
the blue flame, the fluid metal is surrounded by a blaze
of an ultramarine color, and the coal is' incrusted with
oxide of lead. The oxide of lead may be driven by the
blue flame from one place to another, tinging the fliame
at the same time with blue. Salts of lead, whose acids
do not themselves impart a deep color to the exterior
flame, communicate to this an intense ultramarine, when
fused with the poinjt of the blue flame, either on the
platinum wire or in the forceps.
Indium. — Compounds of indium color the flame blue.
Selenium. — If selenium be melted on coal in the blue
flame, it volatilizes, coloring the flame intense ultra-
marine. A deposit of selenium on charcoal presents
the same appearance in the reducing flame.
Chloride of Copper. — Natural or artificial chloride
of copper, ignited on the platinum wire in the blue flame,
tinges the external flame at first intense ultramarine, but
afterwards green from the oxide of copper formed.
Bromide of Copper. — Bromide of copper, treated
in the same way as the chlorMe, colors the flame at first
greenish blue, but afterwards imparts the green of oxide
of copper.
5. — ^Tbst in the Borax Bead.
Since this test serves especially to detect the oxides of
Btetals, it is of the first importance that, if the substance
to bo examined contain unoxidized metals, it s^hould be
Yoasted to oxidize them. Metals combined with sulphur,
aiveniCf Jtc, are not only difficu\l\j ftoVoSAa VxiWml^ but
TB9T IN THE PHOSPHORUS BEAD. 43
«
t
present appearances differing more or less from those of
the oxides. The roasting of the p'ulverized substance
may be performed on coal or in a glass tube. It must
be repeated several times to produce the most complete
oxidation and volatilize perfectly sulphur, arsenic, etc.
Before every new roasting the substance must be ground
in an agate mortar. Sulphides and arsenides of metals
may be advantageously subjected to alternate oxidating
and reducing roastings. The latter are effected by mix-
ing the pulverized assay with coal or plumbago powder,
and then heating it in a glass tube or on charcoal. The
same directions apply to the next test.
6. — Test in the Phosphorus Bead.
In this case, as in the preceding, it is important to
observe accurately the colors which the beads present
while hot, while cooling, and when cold, both in the
oxidizing and reducing flames. Beads, in which certain
substances are dissolved, possess the property of becom-
ing cloudy or opaque, when treated with an intermit-
tent flame. This process is called flaming. The same
result may also generally be produced by a slow and
gentle heating of the previously cooled bead. The
cloudiness of the bead is also often caused merely by the
addition of a larger quantity of the assay.
TABLE L
1. — OxiDiznia Flamb. A. — ^Bobaz.
CoLDU or
Bdrstarce* wbich Exhibit tbekk Couu.
TU BUDl.
/- Ik, Oil Bind.
/- lit CM Beat.
»lia.
eiiiBk,
Alnmin^
sSii,
Oxld«orTln,
1
TellonnuAdd,
Lltn«,
Turia,
f;^^-
™
Oil<t« uf LintliaDiim,
OltdaorSilror,
S3;
Sr*
1
«■£■
Nioblo Acid,
Oxide or silver,
ColBinbla Aold,
4
UolvbdioAirid,
s
Tiisnio Aolii.
Tunenlio Add,
Molclidlo Aold,
OKide or Zlna.
Oxide of Zlno,
li
1
QiMeorCHdmlao),
Oxide or Culuiluin.
i
Qilda or Indmm,
Oxide or ladiuiD,
Olid* Df Load,
OlldBofTh«lltuni,
OxIdeorLcftri.
OildoorThnUinin,
Olidenr BUmuth.
S3
OxIdBorlilitnnlb,
Oxide otiDtimgny.
B?
Oxide of AnlliDonj.
TitonioAoid.Crellow).
^
Tua^CiaAoid.O'Blluw),
7
Molvl-lio Ao.d, (d»rk-
Oi?d«ol'zino, Celigbtlj
Fritou,, rtd-
|5
dUkaiiio-,
lo r^ <n.d
.Oilda or CBdmlnm,
Oxide or Bl>uiuth,(nd-
dlali yellow].
■Oxide or AnUmony,
L
"
46
TABLE I— CONTINUED.
1. — Oxidizing Flame. A. — Borax.
Colors of
thbBkadb.
Red, yellow,
or purple.
Color of
Amethyst,
SUBSTANCBB WHICH BZHIBIT THBSE COLOBB.
In the Hot Bead.
Blue,
Oreen,
Oxide of Cerima, (red).
Oxide. of Iron, (dark red),
Oxide of Uranium, (red),
Vanadic Acid, (yellow),
Oxioe of Chromiam,
(dark-red),
Oxide of Niekol,
Oxide of Maagaoeae,
Oxide of Didymltim.
Oxide of Cobalt.
Oxide of Copper.
In the Cold Be&d,
Oxide of Cenam, (by flaminc
enamel-white).
Oxide of Iron, (yellow).
Oxide of Uraoion, (by !!«•
minsr, enamel-yellow).
Vanadio Add. (yellow).
Oxide uf Niekel, (reddish
brown).
Oxide of Mangaoese, (red,
inolided to Tiolet).
Oxide of IMdyminm.
Oxide of Cobalt,
(xide of Coppei
greemsh-blae).
Oxide of Copper, (blue to
■ lu
Oxide of Chromium, (iacUned
to yellow).
w
I c-^ ■ ■ '-'• '^ •
:* -x r.
TABLE L— COimKUKD.
2. — ^RsDrcDTG Flajo. a. — Bokax.
C^lMtt OF
C0lcrU$s,
Ytliow to
CduHO.
M Oc HbC
OzMttoTTlB,
Lii
Tttrift,
Zireonift,
Thoria,
Oxid« of LMitimoiim,
OzUte of Cennfn,
Oolvmbie Acid,
OxMeof INdyoiiaiii,
Oxtfte of Ifaojpinew.
MiobtoAeuS.lA small qtumiiif.
Oxide of Silrer,
Oxide of Zino,
Oxide of Cadroiam,
Oxide of lodlum,
Oxide of Lead.
Oxide of Tballiam,
Oxide of Bismutiiy
Oxide of Antimony,
Oxide of Nielcei,
Tellaroua Aoid,
TlUnIo Aoid,
Tuutcitlo Acid,
Molyiidlo Acid,
Vanadio Aoid.
Btu: I Oxide of Oob»U.
MOc Cetf
Siliea,
All
OxMoeT
61aeiB%
Tttrte,
Zireuaia,
Thorte,
OxMe of T^uiUMmatn,
Oxide of Cerium,
Colnmbie Aoid.
Oxide of IMdymiam,
Oxide of Manganese.
Niobto Acid, m tmaU qutaUUw.
Oxide of Silrer,
Oxide of Zinc,
Oxide of Cadmiam,
Oxide of Indiam,
Oxide of Lead,
Oxide of Tlialliam,
Oxide of Bismiitby
Oxide of Antimony,
Oxide o( Nieiiel,
Telluroua Aoid.
TiUnicAeid.
Tungstic Acid,
Mulybdio Aoid.
Oxide of Cobalt,
TIUnloAotd.{ 2^£Sg*.
4T
TABLE L— CONTINUED.
2. — Rbducino Flame. A. — Borax.
Colors or
TBI Bbadi.
Ore$n,
Ofay and
cloudy,
{Tht etoudi"
nu» often
antart firtt
dUtinetiy
durlnff the
cooling.
Rod to
brownich'
rod a»d
e/oudy.
SUDBTAMOES WHICH EXUIDIT THItB COLORI.
In the Hot Bead,
Oilde of Tron,
Oxide of Uranium,
Oxldo of Chromium,
Ox'.de of Stiver,
Oxlno of Zinc,
Oxide of Cadmium,
Oxldo of Lead.
Oxide of Dliirauth,
Oxide of Antimony,
Oxide of Nlol(oI,
Tellurous Aoid.
Nloblo Aold
CBi
By longeontin'
ued b/owtng and
targe quantity.
Oxide of Copper.
In- the Cold Bead.
Oxldo of Tron. (hottle-sreen).
Oxldo of Uranium, **
Oxldo of Chromium, (emerald-
($reen).
Vanadlo Aoid, (emerald-green).
Oxldo of Silver,
Oxldo of ZIno,
Oxide ofCadmlum,
Oxide orLead,
Oxide of Uliimuth,
Oxldo of Antimony,
Oxldo of Nioliel,
Tuliuroua Aoid.
CBy longeontin'
Nloblo Aold, < ued bloudng and
(in large quantity.
Oxide of Copper.
TABLE I.— CONHNUED.;
1.— Oxidizing Flahb. B.— Salt op Phosphobtis.
COLDBB OB
»..„„...,
men iiniDiT these Colobi.
TBB Buss.
In at Hot Biad.
M the cm Bui.
811li».(iKrjIiW(M(iiK«
oildSoriin.
TellaroMAold,
SMonui,
QIuoIhb,
zi^!li>,
Mloblo AoM.
■s
BUICfl. {very little lalublt.)
Oji'.S'S'tId,
Telluroui Acid,
Ctlinat.
Barf (a,
Btrootia,
«[»»"«!•,
Yttrl*, '
ZlrooDik,
Oildu of Isnlhannna,
1
Colnrabio Add,
Tltunlo Actil,
Ss&r-
Oxlds or Antlmonr-
1
1
s
Ninblc Aold,
TltaoloABid, '
0» Id of Cadmium,
Oxldo of Indium,
O-idenfLead.
Oiido ot ThalKum,
Oilda of Uleoialh,
Oildoof AatimoDT.
T,Hb«. Ttd-
ColombkAdd,
OildaorslnD.
Oildo or CMlmlum,
Ontds or Lasd.
Oilde or Ulnnuth,
0»Jdo of AntlmoB}',
1
CldeofBllTBt,
Oildooflron.
Oilda 01 NIoksI.
0»ldo of Uranium, (j/'ll
VanodlB Aold,
riiuai
OiideofSllvor.
Ondaof Corlum,
0.1d"rN™kBl,
Oxide nf Cnuilum,
V*n«llo Add.
Oilde of Cnromtnra.
49
TABLE I.— CONTINUED.
1. — Oxidizing Flamk. B. — Salt of Phosphobus.
«
COLOBS OF
Substances wnicn exhibit these Colobb.
THs Beads-
In the Hot Bead.
In the Cold Bead.
Co/or of
Anutkytt.
Oxide of Manganese,
Oxide of Didymituu.
Oxide of Maneanese,
Oxide of Didymium.
Blue,
Oxide of Cobalt.
Oxide of Cobalt,
Oxide of Copper, (to greenish
blue,)
Green,
Oxide of Cop|>er,
Iklotybdie Acid, (ye/lowiah green.
Holybdic Acid, {stight yellow
ieh gre*n).
Oxide of Uranlam, (yellowiah
green).
Oxide of Chromium, (fimerald
green).
50
TABLE l:— CONTINUED.
2. — REDUCiNa Flame. B. — Salt of Phosphorus.
Colors of
THE Beads.
Colorleaa.
TtUow to
h'ood-red
andbroton.
Substances which exhibit these Colobs.
In the Hot Bead.
Silica, {very little soluble),
Alniuina
Oxide of Tin,
Baryta,
StroDtia,
Lime,
Magnesia,
(vlucinai
Yttria.
Zii^Qunia,
Tliuria,
Oxide of Lantbanam,
Oxide of Oeriunii
Coluiubic Aoid,
Oxide of Didymium,
Oxide of Maa;;aDese.
Oxide of Silver,
Oxide of Zino,
Oxide of Cadinfum,
Oxide of indium,
Oxide of Lead.
Oxide of Tliallium,
Oxide of BiHmuth,
Oxide of Antimony,
Oxide of Nickel.
Telluroas Aoid.
• ?
Oxide of Iron, (recOt
Titanio Acid, (yellow)^
Titanic Acid, 1 containing
Niobio Acid, \ Iron, {Jblood*
TuntTBtic Acid, ) red).
Vanadio Aoid, (brownish^
Oxide of Chromium, {reddish)^
In the Cold Bead,
Silica, {very little soluble).
Alumina,
Oxide of Tin.
Baryta,
Stroutia,
Lime,
Mau;ne8ia,
Ulucina,
Yttria,
Zirconia,
Thoria.
5
I
1*3.
Oxide of Lantlianum,
Oxide of Cerium,
Oxide of i):dymium.
Oxide of Manganese,
Columbio Aoia.
Oxide of Silver,
Oxide of Zinc,
Oxide of Cadmium,
Oxide of Indium,
Oxide of Lead.
Oxide of Tiiallium,
Oxide of Bismuth,
Oxide of Antimony,
Oxide of Nickel,
Tellnroua Acid.
Oxide of Irnn,
Tftanic Acid, (containins Iron).
Niobio Acid. " •*
Tungstio Add, " "
TABLE I.— CONTINUED.
2. — Keducing Flamb. B. — Salt of Phosphobus.
Bn»ST*lCCK» WOICH E
IHiniT T8KSB COIOEI.
ins Bbads
JH Ua ffoi BiiBt.
h ». CM ^,«(.
.,.,„.
Moble Asid (6> lor^i quinUUj,).
NIoblo Aoid. [m iorjr. jMaiidF J
TlUoloAcld.
....
Oxldi.ofCohi.lt.
Tunssllo Acid
NioWoAoid, (fninrj(iarfl»fli«m
OxidoorCobolt,
TunuTtloAoid,
Niobio Add. ((» vtry larsijuoH-
'•<!/■)
Grcdi.
Oilde of Urnniiim,
MoljhdieAuid.
Oxido nt Uranium.
M"1)MloAoid.
YaniidioAold.
OildDof tlhtomlani,
eluudj,.
approT, firil
ulti/t the
ine).
OiIdoorBilisr,
OildBorZloo,
Oxtdu of I'admium.
0.ido ..f Lgad.
OildflorBNuuth,
Oitdsof Aritlmaoy.
O.Ida of Mckul,
TuLJuroiu Asld.
cloudy.
Oxide of Copper.
Oildo ofCoppnr.
62
/ .
«..
r\
0, ■:•^;^v.
TABLE n.— BEHAVIOR OP THE METAL-
M€taUie Oxidet in
Alpkakttie Order.
On Charcoal alone.
trUh CmrbommU •/ Soda
1. Antimoni-
ous Acid.
OFl: It is displftoed
wlthoat change, and de-
posited upon another part
of the Ch.
RFl t It is reduced and
7olatlllted. A Ct ofan-
timonious acid is deposit-
ed on the Ch, and a green-
ish blue color imparted
to the flame.
On Ch Terr readily re-
dqced in OF! and RFl.
Toe metal Aimee and eoata
the Ch with aatlmoiiiovi
acid.
2. Arsekious
Acid.
Volatile below red heat.
•
On Ch redaoed, with
emission of arson leal
ftimes. which are charae-
teriied by a strong garlic
odor.
8. Tbroxide
OF Bismuth.
OFl : On platinam fbil
it fuses readily to a dark-
brown mass, which on
cooling becomes pale yel-
low.
On Ch in OFl and RFl
reduced to metallic bis-
muth, which, with long
blowing, vaporizes, coat-
ing the Ch with yellow
oxide. The Ct, when
touched with the RFl,
disappears without color-
ing the flame.
•
Easily redaoed to me-
talUc bismath.
4. Oxide of
i Cadmium.
OFl : On platinam foil
unchanged.
RFl : On Ch it disap-
pears in a short time and
deposits all over the Ch
a darlc yellow or reddish
brown powder; the col-
or can only be clearly
discerned after cooling.
OFl : Insolable.
RFl : On Ch readily re-
duced ; the metal vapor-
izes and deposits a darlc
yellow or reddish brown
Ct on the Ch.
l;-'
6&
Willi S Ph on Platintan H
Ofl: BotablBtoa limpid glitnr of
-dkrk yelluw ur r«il cibir. hIiIoIi
hli;hfrsacuriitwl Willi uililn thegliU'
beooinea im luulln;: vmuiel wIiiIh.
RFIe Tna vBllnir |;liuu heouuiB
oalorieu. A hli;li]y r&LDrntcil Iibbh
OPIi AiKlUi Si, bul oa odoIIiie
KFI: Forltictly solorlosi, liot ud
OFl; Dluotru but alowly,
-tolura iotensltelr. if liltiB uf
I* yelluw, whsn ou'iu'' yullii'
Krsen i olth loore I'XlriB It ii <
>wl, wIiIIb hoi, buouiiiea yellnu
■WiuMuic and wIisd iiBrrojtiy cold
B flns yaUuwi«li Kneu o<>lor.
I( hiu k Boa Kreen wlar.
Tha slui mupBai
HFI: Ad 111 OPl.
TBry InlenslTBly.-
OFl ; A aniill n-ittltfon
qa4nlity tnnmrU tu Ic u i
qnuitltyot oildo Ii»wiidi
but un euoiinx bDOiiniai <
r«fl, (gabuilUs J On Uh
insy DB prBclpiUlvd In t
: ABHltiiBi. butltarthataina
quutiUtyuC DXlde ttis culurlinutw
li.V\: Agliua onnUiDlne ft Urss
qai.ntlty ur<iXlilebEei>iu«Bdirli Krern,
•rbloh lb tllB inuuiiMit uf •ulffllfluk.
ion ohuiEBa puiulunly to brnwnliih
B<l HDil niiHqat. A tiliiu annul n In e
luC lieciimeitiiuWDliili rod end upiqu*
£6
Table II.— CON-
JHeta/lie Oxides in
Atphabetical Order,
9. Teroxide
OP Gold.
10. Oxide of
Indium.
On Charcoal alone.
11. Sesquiox-
IDB OF Iron.
12. BiNOXIDE
OF Iridium.
13. Oxide of
Lead.
When heated to ignition
It becomes reduced to met-
al in OPl and RFJ. The
metal fused ea.sily to a
ulohule.
RPl : Is reduced and forms
a yellow Ct, and wlien
8trnn;5ly heated colors
flame intense blue.
the
With Carbonate of Soda.
Does not dil>^olve in the
Sd, but is easily reduced,
in botii flames. The metal
fuses readily to a sslohule.
Thta Sd passes into the Ch.
RFl : Is red need to soft
metallic globules, like lead.
OFl : Not chanjred.
KFl : Becomes black
majsnetio.
and
At a rcd-hent becomes
rcducfii ; the reduced metal
Id infusible.
Minium, when heated on
platium foil, blackens; on
tncreasin*; the temperature
itchanuei into yellow ox
ide, which Anally fu^es to a
yellow u:lass.
On Ch in OFl and RFl
almost instantaneously re-
du3i(d to metal which, with
continued bbiwinjr, vapor
ize8, and covers theCh with
yellow oxide, surrounded
oy a laint white ring of oar-
bonate. The Ct. when
touched with the RFl dis-
appears, impartinsc to the
JSjtno an azure-blue trnve. \
OFl : Insoluble. /
RFl: OnChitisredaecd:
the mass, when placed in a
mortar, pulverized and re-
peatedly %ia>hed with wa-
ter to remove the adherent
Ch particles, yields a u:ra3'
metallic powder which is
attracted by the magnet.
OFl : Does not disf>ol ve in
the Sd, but beoomea re-
duced ; the metal cannot
be Aised to a globule.
RFl : As in OKI.
OPl: On platincm wire
readily dissolved to a lim-
pid Klass which, on cool'
in:r, becomes yellowish and
opaque.
RPl: On Ch red need to
metal which, witii contin-
ued blowing, covers the Ch
with oxide.
53
Lie OXIDES BEFORE THE BLOWPIPE.
mth Bx on Platinum Wire,
OFLi Dissolves in IfArj^e quanti-
ties t(> a limpid jslass. whicli wtiiie
liot appears yelluwitih, bub after cuul-
lose c«iiurle8>.
Rb i : Tlie ^lass when treated only
JfTH short time in tlieUPl bucumes
on Ch ^rayitth and ulnudy from par-
ticles t*f reduced antimnny. With
tin it becomes giay ur black.
With S Ph on Platinum Wirt,
OFl: A small quantity is ensily
disw^ived t() a clear yellow y:la*s,
'Wiiich on conlinj^ becomes colorless.
Oo a lar;;e addition of oxide the
Iplass while hot is yellowish red, be-
ctimes yellow on cooling, and when
cold is opiileifcent.
RFl : On Ch tlie jslass becomes at
first ^lay and chmdy, the oxide is
reduced to luetal witli efferveK'ence,
and ihe i>ead becomes clear ii>;ain.
An addition of tin accelerates the
reaction.
OFl: Dissolves witli cffervescenea
to a limpid gia.^s, which while hot
IS i4li*4;htly yellowi!>h.
KKl: Oil Ch the saturated bead
becomes at fir:<t c'.oud> , but after-
wards clear a^^ain, owiuj; to the
volatilizaiion of the reduced anti-
mony. Treated with tin, the j^lasfl
becomes alter cooling j;ray, even if
but very little antimoniou.** acid ii
present. With stitmg blowiu^ i(
uecomes clear ujgain.
OFl t Soluble in larjro quantity to
% limpid yellowi^h iilass, itecoiuinj;
almu»it Ofdorless on cooling:. When
tii^^hiy iiatunited it may be made
enamel-white by flamin;;, and when
rtiU more oxide is present it l)e-
eomes by itself enamel-white on
euoiing.
ilFl : Placed on Ch >fc enters into
ebuliit/on; the oxide is reduced ;
t/ie retiuoed metal Fuporizes itumedi-
mteljr aad deyoaita a. dutk yellow Ct.
OFl: Readily dissolved to a lim-
pid yellow j^lass uJiiuh on cooling
becomes coIo^ie^s. When a greater
quantity ot oxide is ple^ent the
^la^s may lie made enamel-white by
llaminu;, and ou a i^tiil ]ar«^er addi-
tion It beciimes by it&elf enamel-
white on Cooling.
IlFl : On Cli, particularly when
tin U added, the ii.lass remains ctdor-
less and limpid when hot. Imt iie-
couies on cooling dark-gray and
opaque.
OFl: Solulde in larjre quantity to
a limpid ;;lai--s whicli wiiilo hot it
yellowI^h, but ctdorless when cold 4
when saturated it becomes euamcL-
whiteou cuolin;r.
RFl : On Ch the oxide Itecomef
slowly and imperfecily reduced.
The reduced vvwtVwV v\^^v>*Wa tk. x>t\>i
l'eo\>\o ex. ot (Va.tV. ^^W^v* <iv.\vvc . 'W^
color \# «\\\^ <i\<i«.t\^ *'t^i\\ viV'iiXi ^^
S4
TABLE IL— CON-
MeialNe {Md€9 in
Jipkmbttieal Order.
& Sesquiox-
IDE OF Ce-
BIUM.
On Ckmreatd mtiome.
Not ehaased.
With
•fS^im.
Insolabl*. TbeSd
i«to Um Ch ; tha Hcu,
ide i« rednood lo prutuxMc
wiiteh remains on the €^
u a Ushi sn^ powiier.
'^ 6. Sbsquiox-
IDK OF Chro-
mium.
7. Oxide of
Cobalt.
Not ehaased.
OFT : Not eban «:ed .
KFI: It is reduced to
metal, hot does not fuse:
the mass is attracted hy the|or,
raasCTiet, and, by frIctioD.
assumes metallic lustre.
OFl : On pUtinani win
Bolable to a dark yelloviah
brown scIms, vhim onoool-
in^ beeomee opsqno and
yellow.
RFl; The glass beeomer
opaque and icreen on eool-
ing On Ch it eannot be
reduced to metal; the t^
pa&ws iuto the Ch, and the
oxide remains behind as a
irreen p«)wJer.
on : On platlnitm wire ■
rer^' small qnantitjr is dia-
K)lved to a transMrmt
masn nf a pale reddi^n onl-
whieh en eooUnj; b>
loumes p'ay
8. Oxide'' OF
Copper.
OFT: Fuses to a black
xlubule. wlilch becomes re
•luce<l where It is ia contact
with the Ch.
RFI: Reduced to metal
at a temperature below thtr
ineltln;e point of copper
When the heat is increased
It uLlobule of metaliio cop-
per Is obtained.
KKl : On Ch redueed to
]Srajr magnetic powder.
OFl: On platinum wire
soluble to a limpil glass of
^nreen color; on oooling It
lieoomes opaque and white.
RFi: On Oh eonljr re-
duced to metal, whieh whoo
the temperature is tnflB<
oiently hUh f ites to one or
tnore globules.
59
TINUED.
With Bx on Platinum Wire
OFl: Colors very iotensively. The
f;l88f*, while hot, is violet, ou cooling;
t a^isames a reddisli tiai^e. When
maeh mao^nese is added, th** ^la^s
1»e<M»ine«i qaite black and opaque:
l>at Uie color can be seen when ihe
fclase. while solt, is flatcened with the
fotoeus.
Rif 1 1 The fclass becomes colorless.
If the color was very dark, the phe-
nomenon IS best observed on Ch with
addition ot tin.
With S Ph on Platinum Wirt.
OFl: <A considerable addition of
man^oese must be ina«lv to produce
a Colored jclass; it then appears,
while hot, brownish violet, ami
reddish violet when cold, but never
opaque. If the flat's contains so
small a quantity of mau^oese that
it appears colorless, an addition of
nitre will produce the cliaracteristle
oolonition .
RPi; Becomes very soon color-
less.
OFl : Dissolved in large quanti-
ties to a limpid 8;liiss waioh. while
hot. appear) yoliow, but oulorleHS on
ooolln.;;. A very lar^^e amount ofldark
acid causes the ^vua to appear dark
yellow, while hot, aud opaline wheo
eoM.
RFl: A hiishly saturatel bea^
beouuies brown and opaque when
•till more acid is present!
OFl I A small quantity colors the
bead violet, while hot; wlien cold
pale reddii«h brown. More oxide
makes the coloration deeper.
RFl : The ^lasd becomes ;;ray and
eloa<iy, or even opaque. With
o«mtinued blowing tlie minute
particles of reduced metal collect
io^ether and the glass bec()ines
colorless. This takes more readily
phioed on 0<i, especially when tin
Madded. The nickel then unites
with (he tin to ft globuie.
OFlt Easily soluble to a limpid
^iass; if but little of the acid is
present it U yell«)wi'*h ^gjc^Qn^ while
hot, but when cold almtist colorless.
On Ch the glass becomes very
, and on cooling assumes a
beautifuljrreen color.
KFl: The glass awumes a very
darn, dirty green color which, on
cooling, heoumes beautiful bright
ii^reen. The same on Ch ; tin deepens
the color a little.
OFl : Soluble to a reddif*h glass
which, on CKiiing, becomes yellow.
A larger addition causes the glass
to appear brownish red, while hot,
and reddish yellow when cold.
RFl: On Platinum wire not
changed. On Ch with tin Itbecames,
at first, gray and opaque; with
continued blowing the nickel
becomes reduced, and the glass clear
again and colorless.
60
TABLE n.— CON-
MttaUic Oxides in
Alphabetical Order.
18. BrNOXIDE
OF Osmium.
19. Protox-
ide OP Palla-
dium.
20. BliNOXIDE
OP Platinum.
On Charcoal alone.
OFI: C«»nverted Into of-
roio aoid, whioli without de-
pnsitin*; a Ot. vuiatilizeo
with ltd peculiar pun^nt
od<»r.
RFl: Ei.'<ny reduced ti>
a d^rk brown and mfUsible
meuiUic powder.
Reduced at a red heat:
but the metallio particle?
are Infusible.
Like Palladium.
Easily reduced to metal-
|lic silver, which unites lu
21. Protox-
ide OP Silver, one or mure globules.
22. Tellu-
Bous Acid.
23. Oxide of
Thallium.
24. BiNOXIDE
OP Tin.
OKI : Fu.«os, and is re
ducad with eflTtirvessenOtt*
The reduced metal becumex
inKtantly vaporized and
Olivers the Ch with teilu-
rnus actd ; the Ct u.-tuaily
liiis a red or dark yellow
ed«:e.
RPl : As in OFI ; the outer
flatne appears bluish g^een
colored.
Volatizos coloring flame
iSreen.
With Carbonate of Soda.
Easily reduced to an In
fusible metallio powder.
Insoluble: TheSd passM
into the Ch,and leaves the
Palladium behind.
Like Palladium.
Instantly reduced. The
S't passes into, the Ch, and
the metal unites to one or
more globules.
OFI : The proto.xide burns,
like tinder, to binoxule.
The binuxide becomes ver^"
Soluble, on platlnam-
wire. to a limpid and color
less «rla.4S, which on coaling
becomes white.
On Ch reduced and rola
tilized, depo-iiling a C( of
teiiurou;) add.
The color of Soda
scures the green color.
ob-
OFI: On platinum wire
luminous and appears, it f«irms with 8d, with eflRBr>
while hot. yellowish, but vescence, an lufusible Com-
assumes <m cuoling a dirty pound
white color. | RFl: On Ch redaoed to
RPl : With a powerful metallio tm^
and continued flame it may
be reduced to metal.
ma fir m etalima
Ji DarbaoHte at Bodi.
Beul onlorleu, aTler auDln^giiy
aount or oxiili
I look volluw
Ul« KXills li
will la l.iit
Klien Diui
the E^Axfl, ,.„.,- „^p^^.^ ^-...
•nd yiilJon. wbea Bold, A utill
Inrser quantity mskei tho eliipj
4>>rk rod. whils hot, and d&rk
yBlln», when eoJd.
KFI: TJiB' Klius heoomcs botllt
prBsn. Treaf-d un Oli ftlth till 11
GccuuiGB, nt nmt. Iiotcra-^n^on, bol
A 8 Ph m FUUiitiin Wirt
A* with OBTbanato of Sods.
. When Bt II uorulnuuliituf
. Einn tho ulaM, iFhlls h-<t,
m'*S"a?ns "m" BrTt "j'i^lo*. t" a
friwnish nnd, Unilly, oulurlcn>. Oa
> Tsry larm nddltion or oxide It
ippeiiiv, whilB liol. dBBu red, honiin-
ng. on cuDllnj, bniwnleh red. then
if n dirty crvea color, and [11111117
Aj wltb Carboonta of Si
OFI : E*Bllr nolnWo
jBllonf gliwa which,
Moum« colurlerD. It
by Djunli
1 Urjar-dJ
bead Id boi
1 tlis gliUB bocomia cloai
t\ I Ai vlth ni. But to o1>.
I a glara wlilcli (ppo^ri yellnv,
U hilt, a hirso addition ul Ui*
le \i required.
FN On Ch Ihe eliv ~
I'lsh nnd cloudy. Tbla
68
TABLE n.— CON-
Metafile OxidM in
Alphabetical Order,
.. 14. SiiBQox-
,C idbofMan-
i'.; GANESB.
OPl : Insoluble. When
the temperature \b roffi*
ciently hi^h both the fe?-
quioxide and th<« peroxide
are converted into a reddish
brown powder.
KFl ; The same effect.
15. Protox-
ide OF Mer-
cury.
16. molybdic
Acid.
On Charcoal alone.
With Carbonate of Soda,
Ir.stantlv reduced and
volatilizea.
0F1: On platinum wire
or foil a very vtnall quan
tity dissolves tn a trans-
parent isreen mass, which
on coolins becomes opaque
and hlui^h screen.
RPl: OnCh it cannot be
reduced to metal ; the 8d
tianses into the Ch and
eaves the protoxide be-
hind.
Heated in a matrass tr*
redncM, it in redueed and
vaporized. The vauorn oon-
denfie in the neck of the
luatraiid and form a metallic
coaling.
OFl : Fuses, becomes
brown, vaporizfS, and dc- OFl : On platinum wire
poMts on the Ch a yellow dissolves with effervcKeence
Ct, which nearest to the.to a limpid glass which,
assay is crystalline.. Onion cooling, becomes milk
cooling the Ct becomes white
white and the crystals ooUl RFI: Fusion with effer'
urless. Ivefcence. The fused mass
RKl: The greater part of is adsorbed by the Ch, and
the assay is absorbed by {part of the acid Is reduoed
the Ch, and may be reduced,io metiil which may be ob-
to metal at a sufficiently tained as a steel-gray pow
\
17. Oxide of
Nickel.
high temperature ; the met-
al ii> in the shape of a gray
powder.
OFl: Not changed.
RPl: On Ch reduced to
metal ; the spongy ma^is
cannot be fused to a glo-
bule, but aitsumes metallic
lustre by irict.on ; it U at-
tracted by the magnet.
der.
OFl: Insoluble.
RFI: Easily reduoed to
metal in the shape of bright
white scales, which are at-
tracted by the magnet.
i^NTJBD.
n Plalinum ITiri.
0P1: Eiflly Bnliihlo tn a. VoipM
rt»« '
RPI: Whan onnUlaIng bat lltt
tItiLniD sold the fiUu becoin
lelLiw, tT).SD mnro. dark yelLiw
\n>wn. A i-Btunileil glnia booom
eDnmel-blae tiy flnialng.
OPI: LlkstiUnlQiuSKl.
RFI ; A Klun. cnntnlnli^x bi
Hum iDnntlo sold, li nntchnnsDi
When uinre.ic hecnrnm i-slluw nni
.on o.wtin!', yeltuBlBh hroirn.
nPU Deh&TBs llke>(ieqiildil(lsor'
Iron Tiio icntn hciid. ithen ~' -
certain pnlnl nf aatunitlon, mi., ...
uiHde libiDk by flniDln^c, On Ch
wlib tin It beonmei dkck yollutt
Tuiadle aold
RP]-. The class, Hbllobnt.appoB
•slur on ooallns.
JFUhS PkmP/alinK
Oi]-.
Ed^Iy diBfolroil tn A limpid
oumea coInrleMcn onollns-
lal^'^JiaittrnJor. "ll !r."i? Ii
ijreSBnt tbo jrliiSS. on (KK-lIng,
womes bruirDi^h rod ; with tin on
.... of iron i>s very comld-
OFh Eiullydlaaolreil ton limpid
nit colorless head, whloh. olisn
I<:b1y . Mtumted, ■ppesri yellow,
nH: vritb llttlo bloving th«
;laM eBpoarK.nhllo hol.nfa dirty
THn onlur. blue un onollnic; "Ha
.Jeep ii,nm. U iron la present, ths
red , ' with (in on (:b Ihe iilau
irun IB conBldcrnblo. i;rcga.
OFl: niMcIrestoi
l<w nbich. on eu
E.'?l'!'¥h™t'l'e" 1
Soluble tn B limpid irlass
64
Table II.— CON-
Mtttdltie Oxidea in
Alpkabtticai itrder.
29. Oxide
Zinc.
On Charcoal alone.
OFl : When heated he-
comes yellow and, on cool-
OFln;;, white a;i;ain. It fuses
nut, hut becutnes very 1am-
Innus.
RPl : Is slowly redaeed ;
the red need metal becomes
rapidly re-oxldixed and the
oxide deposited oa another
part of the Ch.
Wtth Carbonate of Soda,
OFl : Insolnhle.
RFl : On Ch It heoomec
red need . Th e metal vapor-
izes and coats the Ch with
with oxide. With a power-
ful fl&me the ehanioteri»tio
zinc flame is sometunea pro-
duced.
61
TINUED.
With B» on Platinum Wire,
OF1 and RFl: Retlneed, hat not
dissolved: the nieU'tio particle*
«auDot be fused to a j^lubale.
Like Palladiam.
OFl: In part disitolved. and fa
pnrt reduceff. Oi cooling; the trhiss
Deeomea opalescent or milk white,
«ccordini; to the amount of oxide
prttiient.
RKi. The ^;lAsa nt fir^t becomes
fcray, but afterwards limpid and
colorless.
With S Ph on Platinum Wire,
As with Bz.
Like Palladium.
OFl: Imparts to the head a
yuliowiiih niilor. When much uf the
oxide is present the lelas-*. when
cold, is opnlescent and appears
yeli(>wl^'h Ht day-lij^ht, reddish at
candle-ligihl.
RFl: As with Dx.
Oil: Soluble to a limpid and
4Solorie'S ^bis^ which, on (Jh, becomes
gray from reduced metal.
RFl • On Oh becomes at first gray,
afterwards colorless. The Ch
beoomes coated with tellurous acid
Glasfl. Colorless when saturated,
opaque on cuolm;^.
OFl : A very small quantity
dissolves slowly to a limpid anu
odorless i^lass, which remains so
on ooolinjc.
RFl : From a highly saturated
KlaiM a part of the oxide may be
reduced on Cii.
Aa with Borax.
As with Borax.
OFl : As with Borax.
RFl : The ^slass, containing oxide,
suffers no change.
TABLE IL—€ON>
graft g^r aa wuaKgfSrf^.
11
: IKS)]:: iki>:iii<tffftl:
I
I
ill— iiiiM iTliBii. 81..:. wist: mint- :^.:{tn«r3U^.
(BEDtt^lfflC
IfaAMBlHIr
IMl
t^fTimfl WT* ' ^ Tmfmw
I
EARTHS AND THE EARTHS PROPER,
BLOWPIPE.
frith Bx on Platinum JFirt,
mtk S Pk on Platinum fTirt,
* The Carhnnate dissolves with ef-
'forvesoenoe to a lliiapiil «£la^s, whioh
jwhun In a certain ptata of, satura-
itlon « may ^ be i made * opaqae hy
^flamlnic ; ^when still more saturated
Jl heo(>me«i opaque on oooUnX) evea
.Without flamint;. .
*
At with Bonuc.
•
1 1
Like Baryta.
Like Baryta.
•
f
KeadiU' dissolved to a limpid
flass. which becomes opaque by
flamiuz. The Carbonate diiitfulves
with efftfrvei^ence. On a large afidl-
tion of Lime the jsloss crystallize*
on coolini^, but does not become
enamet-white.
Soluble in large quantities to a
limpid glass which, when suffioient
Lime h present, becomes opaque by
flaming. When saturatsd, the glasi
becomes enamel-white on cooling.
It behaves like Lime, but does not
orystallixe so well.
Dlfsolves slowly to a limpid
l^lass. whioh remains so on cooling,
and which cannot be made cloudy
by flaming. A Urge quantity of
Alumina makes the glass cloudy}
on cooling, it assumes a crystalline
•ariisMe.
Readily soluble to a limpid glasSf
winch liecoines opaque hy flaming.
When saturated. It beoomes on cooli
ingenamel-vrhite.
Soluble to a limpid glas.*. which
remams clear under nil circum tiin-
ces. If toil much Alumina is added,
the undissolved portion becomea
translucent.
\
C8
Table m.— CON-
6. Glucina.
7. Yttria.
8. ZiRCONIA
On Ch alone and in tkt
Forcepa.
Not changed.
Not cDaoged.
InfVislhle, hut ntnittio*
vory brilliant li;sht.
WHk Coronate of Soda
on Ch.
lofolublo.
Insoluble.
loflolablo.
TINUED.
65
mth Bx on Platinum Wire.
OFl: Dissolves readily and in
larjce quantity to a limpid j^lafs
irhicti aupeara yellowish white hot;
on cooltnis it is colorless. When
BBUOh of the exile is present the
SlatrS may be made ennmel •white
y flamin*;; and on a still larj^r
addition it becomes enamel white on
eo<din<;.
RPI: The saturated glass becomes
at first sx^y and cloudy, and finally
lUransparent a«;ain. On Ch the
oxide becomes rednced, the metal
raporlses and coats the Ch with
oxide.
WV.k S Ph on Platinum Wire.
As with Borax.
66
TABLE m.— BEHAVIOR OF THE ALKAXINB
BEFORE THE
Or Ck tOone and in the
Foreepa,
JFith Carbonate of Soda
on Ch.
1. B'AKTTA.
Th« ITjdrate ftipes, bolls,
fBtametods and U finally ab-
■orbed by the Ch. - Tho Car-
boiMlt niMi readily to a
tranfiparont Klas.'i, wuich on
oodUqk beoomed enamel-
white. . In the forcepi it col-
ort the outer flame yellow
iihirreen.
' Fuses with Sd to a homo-
geneous mass, which is ab-
sorbed by the Ch.
^ Stron-
TIA.
TlijB Hydrate behares like
hydrate of baryta. The Car-
bunate fuses only at the
•djcet, and iirell:! out
in arborescent ramifications
whioh emit a brilliant Ujcht,
and when heated with the
RKl impart to it a reddish
tinge; shows after cooling
alkaline reaction, in the for-
Mps, colon the outer flame
purple.
Caustic Strontia is insolu
ble. The CarbunaU) mixed
with its own vuluine of Sd
nises into a limpid gia^s,
which becomes enatnol-white
on coolin;;. At a greater
heat the masrf enters into
ebullUitin, and caustic Stron-
tia is formed, which is ab-
sorbed by the Ch.
SlIlMB.
•
Caustic Lime suflbrs no
alteration. The Curitonate
lines carbonic acid, becume^
whiter and more luminous,
and shows alter coullnj; al-
kaline reaction. In the for-
oepa it colon the outer flame
pale red.
Insoluble. The Sd passes
into the Ch and leaves the
Lime unaltered on its bur-
&ce.
^ Magne-
sia.
Uudereoes no alterations.
The Oarnonato becomes cau-
stic and luminous.
It bohares like Lime.
^ XWXINA
1
•
Not chanced-
Torms an inftislble com-
pound, with slight intumes-
cence. The excess of Sd hi
absorbed by the Ch.
TmUED.
69
With Bx on Platinum Wirt.
With SFhon Platinnm Wire,
Soluble In larjj^ qnantitles to a
limpid iclaj», ivhich Ixscomes opaqae
by Uainlog When (ilucina l» pres-
ent in ezcera It becomei enamel
white on cooling.
As with Borax.
Like Gluoina.
Like Qlocina.
Like Glaelna.
Dissolves more slowly than with
Borax.
The BubstDDce to be examined is pulverized, mix*
■willi soda, moistened a little and spread on coal. At
first it should bo heated gently, but after the moisture is
driven off the temperature sliould he raised as high as
possible. It sliould now bo observed, first, vrlioiher Iho
assay effervesces, and fuses with the soda ; or second,
whether it is reduced ; or third, whelher neither one nor
the other occurs, in ivhich case ihc molted soda sinks
.gradually into the coal, and the assay remains unchanged.
I Silicic, titanic, tungstic and molybdic acids effervesce,
k-and fuse with the soda. Silicic and lilanic acids under
■ Ihese circumstances melt to a bend. The foimoronly
gives, (when not too much Foda is employed), a bead
which remains transparent after cooling, while that of
the latter becomes, in cooling, opaque and crystalline.
Tungstic and molybdic acids are absorbed by tbo coal as
tungstate and molybdate of soda. It should also bo no-
ticed hero that salts of baryta and strontia form, when
fused with soda, compounds wliich arc absorbed by the
coal.
All tlie oxides of the noble metals, as well aa the ox-
iJes and acids of molybdenum, tungsten, antimoDrJ
TEST WITH SODA. 71
arsenic, tellurium, copper, quicksilver, bismuth, tin, lead,
zinc, cadmium, nickel, cobalt and iron arc reduced on
coal with soda, when heated by the reducing flame.
Arsenic and quicksilver are instantly volatilized, and
sometimes leave behind a scarcely perceptible deposit on
the coal. Antimony, tellurium, bismuth, lead, thallium,
zinc, cadmium and indium are partially volatilized, and
form on the coal distinct incrustations. The fixed
metals, when thus reduced, are found either melted or
anmelted in the soda, and are best detected by grinding
the part of the coal into which the soda lias sunk in an
agate mortar, and carefully washing off the particles of
coal with water. Those metals which are fusible and
malleable remain in the mortar as flat pieces and scales,
and the infusible s^nd unmalleable as a powder with a
metallic luster. Instead of soda, it is better, according
to Plattner, to use with those oxides which are reduced
with difficulty, oxalate of potassa. Soda is, moreovcfi
employed as a special reagent for detecting manganese,
especially when present in very small quantity. When
a substance containing manganese is fused on platinum
fail in the oxidizing flame with soda, or better with a
mixture of soda and saltpeter, a mass is obtained which
is colored green, or when cold bluish green, by mangar
nate of soda.
8. — Special Tests.
By the methods thus far given for assaying with the
blowpipe, it is not always possible to decido with certainty
apoD all the substances which may ^i^^^T^>aM\.\\.\^^£X!ssx
p
|'2 SPECIAL TESTS,
necessary to undertake for this purpose still further e
peiiments, Tlieso experiments, which have lor their
object the special determination of certain substances, or
serve to coiilirin results previously obtained, are biiefly
given below.
PoTASSA. — The presence of potassa in substances,
whij . besides this contain so much soda or lithia. as to
prevent its reaction on tlic blue flame of the blowpipe,
(seo Test in the Platinum Forceps); can, wlien the
qua.otity is sufficiently large, bo proved bj dissolving in
a bead of borax, colored brownish by oxide of nickel, a
portion of the assay, and observing the color of the bead
when cold. A mora or less distinct bluish tinge denotes
the presence of potassa. Since the reaction depends, of
course, upon the quantity of the assay in the bead, it
must be gradually increased to the required amount.
The bead must bo heated on the platinum wire in the
oxidating flame.
Ltthia. — Si!icat03 which contain only a small quantity
of lithia, as, for instance, many lurmalines and scapohtes,
either do not redden the exterior flame at all or only
very slightly. In this cose it is neseasary to adopt the
method proposed by Tamer, by which even a small
amount of lithia may be detected. Tlia process is as
follows : The silicate is pulverized as finely as possible
and made into a paste with a mixture of one part of
fluor-spar with one and a half parts of bisulphate of
potassa and a little water, and fused on tlie platinum wire
in the blue flame, the color of the exterior flame beinj
refalij not\oo&.. According to ilcrlet, it is <
8PSCIAL TE3IS. 78
necessary in order to be positire ia regard to the reaction
to use two parts of tlie mixture with one part ot the
assaj. If the silicate coutaios a small qaantity of lithia,
the outer flame will be colored red, though not so brightly
as from lithia alone, the color iacliniiig strongly to the
violet of the potassa. If the silicate be free from lithia,
only the violet color of the patasia appears. If it con-
tains soda, it is not always possible to obtain a distinct
reaction from the lithia. K boracic acid be present in
the silicate, as ia turmaliac, the outer fljime exhibits first
a green tinge denoting the presenc3 of jjhe acid, but
afterwards a wine or less intense red from the lithia.
Another method of detecting lithia when mixed with soda
13 said to be to dip the assay, mDistcned with hydrochloric
acid, into melted wax and then heat it in the blue flame,
by which, at the first moment, a red color is produced.
Boracic Acid. — Turner has proposed the following
method of testing for boracic acid in salts and minerals :
The assay is to be pulverized as finely as possible and
made into a paste with water and a flux consisting of
four and a half parts of bisulphate of potassa and one
part of fluor-spar, which is perfectly frqe from boracic
acid, and fused on the platinum wire in the blue flame.
While the mass is fusing fluo-boracic acid is formed
which is driven off and colors the exterior flame a deep
yellowish green, (siskin-grean.) The green color of the
flame continues, however, only so long as fluo-boracic
acid gas is diaengxged. If, therefore, the quantity of
boracic acid be small, strict attention must be given^
SPECIAL TESXS.
i"
^^F^DCe the color lasts only the few Eeconds in -which the
^H nmtQrials of tlie bead are operating on each otbcr. Ac-
^" cording to Mcrlet, it ia often necessary, iii order to obtain
a reliable result, to employ with one part ot the assay
tbreo or four parts of the flux.
Silicic Acid. — This may be most easily detected in
silicates by heating a small splinter or fragment in a bead
of salt of phosphorus, The silicic acid, being nearly
insoluble in tlio salt, is separated from the soluble parts
nnd forms a more or less transparent mass of the form
of the assay nsed, nhieh is called a siliceous skeleton.
SoLPnuRic Acid and Sulphdr. — In sulphates, sul-
phide?, and indeed in all substances containing sulphur,
tha smallest trace even of this element may be detected
by mixing tho assay with two or three parts of soda, or
according to Plattner, wilh the same quantity of oxalate
of potassft, (which is perfectly free from sulphuric acid),
and heating the mixture in the reducing flame on char-
coal. The melted mass, when cold, is laid, with Umt
part of the eo.il into which it has sunk, on a piece of
bright silver and moistened with water. If sulphur be
present and has accordingly formed sulphide of sodium,
there appears sooner or later a. black or brown stain of
Bulphide on the silver. It must, however, be observed
that selenium gives tlie same reaction. Von Kohell gives
the following directions for determining whether the
flutphur in a mineral belongs to a sulphide or to a buI-
pliaie. Tho finely pulverized assay is fused with hydraj^^^
^^m-aif/x)tiissn ia aplalinum spcon before the blowpipe. Tt^^f
%
< SPECIAL TESTS. 76
platinum spoon with its contents is then placed with a
bright piece of silver in a small porcelain dish of water.
If the substance contains a sulphide, the silver is
blackened, but if a sulphate, it remains perfectly bright*
In the latter case, the sulphur must first be proved
present on coal with soda, and, of course, that portion
which is melted in the platinum spoon must not have
been exposed to any reducing influence.
Nitric Acid. — Nitrates heated in a matrass give oflF
first oxygen, and then nitrous acid, which may be
recognized from its yellow color as well as peculiar odor.
Nitrates of potassa and soda deflagrate when heated on
charcoal. A small quantity of nitric acid may be de«
tected in a substance by heating a portion of it in a
matrass with a little more than an equal weight of bi-
sulphate of potassa. The color of tho nitrous acid gas
may be tiaost distinctly seen by looking directly into the
open end of the matrass and thus through as thick a
stratum as possible of the mixed -gases.
Fluorine. — ^When hydrofluoric acid in small quantity
occurs in minerals with any of the heavier metals and a
small quantity of water, it is only necessary, according
to Berzelius, to heat the assay in a glass tube closed at
one end, and into the open end to introduce a strip of
moistened Brazil-wood paper. Hydrofluosilicic acid is
driven oflF by the heat and deposits not far from the assay
a ring cf s'lica, and the Brazil-wood paper is turned
straw-yellow by the action of the resulting hydrofluoric
SPECIAL TESTS.
1
F
^^ncid. This reaction maj be obtained, when as in some
^B luicaa tlio li^drofltLoric acid amounts to no more than
^^Bthrcc-fourtha of one per cent. If ihu sabstance, yhetlier
^^ni uiiierfil or a &1og, exhibits no reaction of hydrofluoric
^^RWtd either on the gla^s or the Brazil-wood pnper, it
^" 'Should, aocording to Berzelius, be treated as folloi
Tho piiIvoriz;d assay is mixed with Bilt of phospliori
wliich has been previously melted on coal and then
Terized, and heated at ono end of an open glass tube,
that tlio current of hot air shall pass over it and ihrougli
tlio tube. Minerals conlaimng no silicic acid, treated in
thia way, give off water and hydrofluoric acid, which
passing through tho tube may lo recognized as well by-
its siifiJcoting odor as by its power of attacking Ihe gloss
which is rendered dim throughout ils entire length,
especially in those places where moisture is deposited.
If a strip of moistened Bmzil-wood paper be held before
the current of air at the upper end of tho lube, it is
turned yellow by ihe hydrofluoric acid. If the siib-
Btanco contain silicic acid, fluoride of silicon J3 given off,
which is, however, decomposed by the water formed hy
the combustion of tho alcohol or oil, and (he silica re-
mains dissolved in it. When the water condensed in tho
tube is evajiorated, tlic silica remains behind and may bo
dietinutly seen. If the lubo be washed with water ami
-dried, tho etching effect of the hydrofluoric acid may be
l»erved on thn gloss. A strip of moistened Brazil-wood
r introduced into the tube at tho beginning of the
lariraent is colored yellow. Since in sue
fuse the Biibstances,
SPECIAL TESTS. 77
happens in using glass tubes tbat the glass becomes so
soft that the blowing must be suspended. To avoid this
di£Bculty, Smithson fastiens to one end of the glass tube
by means of a metallic wire a piece of platinum foil so
that it forms a half-tube or canal outside the glass tube.
The assay is now laid on the foil and the blast so directed
as to drive the products of the ignition into the tube.
The use of the wire may be dispensed with by cutting
down the sides of a strip of foil for two thirds of its
length and then rolling it together and introducing the
other third into the glass tube. This has the advantage
of preventing the assay, during or after the fusion, from
coming in contact with the glass. Plattner always
obtains in this way satisfactory results with both minerals
and slags, whether the fluorine constitute an essential
part of the substance or be present only as an accidental
ingredient. According to Merlet, substances which do
not contain too small a quantity of fluorine may be tested
by heating them, after being finely pulverized, in a mat
rass with equal parts, (according to Berzelius with four
parts), of fused bisulphate of potassa, till sulphuric acid
begins to be set free. The heat, which may be that of a
spirit lamp or of the blowpipe flame, should not be ap-
plied to the bottom of the matrass but to the side, since
otherivise the mass is apt to rise in the tube. The empty
part of the matrass becomes thus lined with silica which
is deposited by the decomposition of fluosilicic acid gas.
The tube may then be cut oflF just above the melted mass,
rinsed with water and dried with bibulous paper. If the
quantity of fluorine be considerable^ tUa vcilla qC tha
78 SFBCIAL TESIS.
taba are etched throagfaoat ; if the quantity be small,
they show only here and there a dim spot This method
is, however, not so good for detecting minute quantities of
hydroflooric acid as that with salt of pho^horus in the
open glass tube.
Chlorine, (Chlorides and Chlorates). — ^Accord-
ing to Berzeliiis, the presence of chlorine in its com-
pounds is detected as follows : A^ bead of salt of phos-
phorus is heated in the oxidizing flame and a sufficient
quantity of oxide of copper added gradually to render
it nearly opaque. A portion of tlie substance to be
tested is attached to the still fluid bead, which is then
heated in the reducing flame. If chlorine be present, the
bead is surrounded by a ^me of a beautiful blue in-
clining to purple, which continues as long as chlorine
remains. A fresh portion of the assay renews the
reaction. No other acid found in minerals, except
bromine, produces a similar flame. A second method,
also given by Berzelius, for detecting chlorine in the
metallic chlorides, which are soluble in water, is to lay
upon a bright piece of silver a little sulphate of iron or
copper, Inoisten with a few drops of water, and then to
place in it a portion of the chloride. The silver becomes
afler a while stained of a deep bronze color. According
to Merlet, the insoluble chlorides may be tested for
chlorine in the same way by first melting them with soda
on the platinum wire so to form soluble chloride of sodium*
Badmine. — ^According to Berzelius, the metallic
SPECIAL TESTS. 79
bromides give with salt of phosphorus and oxide of
copper the same reaction as the chlorides ; but the blue
color imparted to the flame bj bromine inclines not to
purple, but to green, especially on the edges. To dis-
tinguish with certainty the bromides and bromates from
the chlorides and chlorates, it is necessary, according to
Berzelius, to fuse them in a matrass with bisulphate of
potassa. When thus treated, the former give ofiF bromine
and sulphurous acid, (and the latter, chlorine and sul-
phurou3 acid), and fill the matrass with reddish-yellow
vapors which may be distinctly recognized by their of-
fensive odor resembling that of chlorine, notwithstanding
the presence of sulphurous acid. If the quantity of
bromine in the assay is small and the foregoing method
be employed, it is important when the color cannot be
observed from the side of the matrass, to look directly
into it through the thickest possible stratum of gis. If
the assay contain chlorine, this is also given off under
these circumstances, but the yellow color is in small
quantities scarcely perceptible. When iodine is also
pressnt, a mixture of yellow vapors of bromine and violet
vapors of iodine is obtained.
Iodine, (Metallic Iodides and Iodates). — Me-
tallic iodides, according to Berzelius, when tested in the
bead of salt of phosphorus and oxide of copper, commu-
nicate to the exterior flame of the blowpipe a beautiful
deep green color. When fused with bisulphate of potassa
in the matrass, they give off sulphurous acid and iodine
which is partly sublimed and partly fills the tube with
^^^^^^^
80 SPECIAL TESTS.
violet .vapors. To discover a small amount of iodine in
mineral water which has been freed from the greater
part of its chloride of sodium by evaporation, a solution
of starch in boiling water and water saturated with
chlorine is generally employed, an insoluble compound
b^ing thus formed, which possesses a remarkably fine
blue color. Heine uses, with better results, instead of
chloriiio water nitric acid, and tests as follows : Tho
neutral fluid to be examined for iodine is mixed with a
small quantity of a solution of starch in hot water, and
stirred with a glass rod while a few drops of nitric acid
are added. If iodine be present even in very small
quantity, there appears directly an intense blue color.
Magnesia, Columbic Acid, Alumina, Oxides op
Zinc, Tin and Antimony, Titanic Acid, Niobic
Acid, Zirconia. — All these substances, when moist-
ened with a solution of nitrate of cobalt and ignited,
assume certain characteristic colors. The pulverized
assay should be made into a stiff paste with water,
spread on coal and gently heated. After the water is
evaporated a drop of the solution of cobalt is to be
added, which is absorbed by the dry porous mass. This
should then bo gently heated to decompose the nitrate
of cobalt, and afterwards strongly ignited by the oxida-
ting flame. When the assay is perfectly cold, theso
substances exhibit the following colors :
Magnesia, rose red, (not intense) ; Columbic Acid,
similar to magnesia.
AJumma,j beautifal blue, (smalt blue).
SPECIAL TESlS. 81
Oxide of Zinc, beautiful yellowish-green, (siskin
green) ; Oxide of Tin, bluish-green ; Oxide of Anti-
monj, dirty green ; Titanic Acid, yellowish-green, (less
beautiful than oxide of zinc) ; Niobic Acid, dirty green.
Zirconia, dirty violet
The purity of the substances is an important requisite
to the proper production of these colora. Impurities
from other oxides give rise to 'more or less indistinct,
dirty colors ; the presence of the alkalies and of silicic
acid causes, (by their melting with the oxide of cobalt,)
a blue color.
Oxide op Manganese. — Exce^ingly minute quan-
tities of the oxide of manganese — even less than one-
tenth of one per cent. — miy be detested by fusing the
finely pulverized assay in the oxidating flame on plati-
jium foil with two parts of soda and one part of salt-
peter. The fused mass is more or less intensely colored
by the manganate of soda ; when hot, it appears green,
when cold, bluish-green, (turquois-color).
Tellurium. — A test for tellurium, proposed by Ber-
zelius, is to grind the assay with soda and coal, and heat
the mass to fusion in a matrass, and drop upon it when
cold a small quantity of recently boiled water. This
after a little time is colored more or less intensely pur-
plish red from the dissolved telluret of sodium.
Arsenic. — A small quantity of arsenic in a metallic
compound, as for instance, in nickel, cobalt, or any alloy
containing arsenic, can often be detected '^llk «\l&:.v^^<S)^
9f
■■ . SPECIAL TE3T3,
certainty neither in the matrass nor on coal. Plattner
cmp!oj3 for this purpose the foUowiog method: One part,
(50 to 75 milligrams), of the finely pulverized metallic
ipound is heated iu a platinum spoon as hot as possi-
Ig with five or six parts of saltpeter. Tho n^etals are
■fliiia oxidized and arseuiate of potassa formed. The
apoon is then boiled with water in a porcelain vessel till
the melted mass is perfectly dissolved from it. After
the metallic osides havo settled to the bottom the solu-
tion is poured off into a porcelain dish, mixed with a few
drops of sulphuric acid aud evaporated, to drive off all
nitric acid, to dryness, or, if too much sulphuric acid
has been added, till only bisulphate of potassa remains,
which on cooling solidifies. In either case, the mass is
ground in aa agate mortar with about throe parts of ox-
alate of potassa and a small quantity of coal. The
mixture is then put into a matrass, warmed at first gently
to drive off all moisture, which may be removed by
means of a roll of bibulous papsr, and heated to redness.
The arsenic acid is reduced to metallic arsenic, which is
sublimed and deposited in the narrow part of tho mat-
rass. If, when the quantity of arsenic present is very
small, tho sublimate of metallic arsenic is not distinct,
V.io neck of tliQ matrass should be cut off with a file and
the part, in which the sublimate is, heated iu tho flame of
the spirit lamp. If this consist of arsouic, it is vola
tilized and may be detected by the odor.
According to Plattiier's experience, the oxalate of j
tassa. and coal may be advantageously employed t
oiier cases for the deteotioa of iisaenic. Conipod
SfGCIAL TBST3. 884
hh contain arsenic and arsenioua acitla are, wlien
»t€d as aboYe, completely reduced und give a ring of
c ar-enic. Even Bulpliiiret of arsenic, when piil-
BTized with four or fire parts of oxalate of potussa and
: coal, and iha mixttirc heated in a matrass, is
iSpletely decomposed, sulphide of potassium being ■
med and metallic arsenic sublimed. •■
I A similar result is obtained, according to Freaeninitl
I Von Babo, when tbo finely pulverized substance
mtaining arsenic is put into a matrass with six parts of
■ mixturo of equal parts of cyanide of potassium and dry
yds. and heated gradually to redness. It is particularly
joportaQt to the success of these tests that the mixture
B heated be perfectly free fr'om water, since a small
intiiy of this not only causes the mass to swell up and
in tho matrass, but may also easily produce the oxi-
11 of the sublimated araenic. The following method
10 adapted to the detection of a small quantity of
jenie : Tiie finely pulverized substance is ground with
I or six parts of saltpeter and fused in a platinum
. The fused mass is treated with boiling water as
above, and to the solution filtered from the
aidue is added a slight excess of acetic acid. The _
i is then boiled to drive off all the carbonic acid, a
crystal of nitrate of silver laid in tlie solution.
senic be present, it having been oxidized by tho pre^
IS treatment to arsenic acid, forms ai'sciiiate of siln
s easily recogEiized firom its reddish brown coloi;
L Pbosphoros. — Small quantities of phosphoruE, '<k^usS
84 SPECIAL TESTS.
it is impossible to detect bj the test in the platinum
forceps, may be discovered as follows : A mixture is
prepared of one part of saltpeter, three parts of soda and
one of silicic acid. Tlie substance to be tested for
phosphorus is ground i:i an agate mortar with five parts
of the above mixture and the wliole fused in a platinum
spoon. The fused mass is then boiled in water and the
solution poured off from the residuo and treated with a
solution of carbonate of ammonia. By long continued
boiling, the silicic acid which was dissolved in the car-
bonate of soda is precipitated and filtered off. The fil-
tered fluid is rendered slightly sour by acetic acid,
boiled to expel all the carbonic acid, and the phosphorus
then tested for with nitrate of silver as in the preceding
method. The appearance of a yellow precipitate o!
phosphate of silver denotes the presence of phosphorur,
which, if originally present in an unoxidized condition,
has by the above treatment been oxidized to phosphoric
acid.
THE END.
;,N*^
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