| By Author | [ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | Other Symbols ] |
| By Title | [ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | Other Symbols ] |
| By Language |
|
Download this book: [ ASCII | HTML | PDF ] Look for this book on Amazon Tweet |
Title: A System of Instruction in the Practical Use of the Blowpipe - Being A Graduated Course Of Analysis For The Use Of Students And All Those Engaged In The Examination Of Metallic Combinations
Author: Anonymous
Language: English
As this book started as an ASCII text book there are no pictures available.
*** Start of this LibraryBlog Digital Book "A System of Instruction in the Practical Use of the Blowpipe - Being A Graduated Course Of Analysis For The Use Of Students And All Those Engaged In The Examination Of Metallic Combinations" ***
A
SYSTEM OF INSTRUCTION
IN
THE PRACTICAL USE
OF
THE BLOWPIPE.
BEING A GRADUATED COURSE OF ANALYSIS FOR THE USE OF STUDENTS
AND ALL THOSE ENGAGED IN THE EXAMINATION OF METALLIC
COMBINATIONS.
NEW YORK:
H. BAILLIÈRE, 290 BROADWAY,
AND 219 REGENT STREET, LONDON.
PARIS: J.B. BAILLIÈRE ET FILS, RUE HAUTEFEUILLE.
MADRID: C. BAILLY-BAILLIÈRE, CALLE DEL PRINCIPE.
1858.
* * * * *
ENTERED according to Act of Congress, in the year 1858, by
C.E. BAILLIÈRE,
In the Clerk's Office of the District Court of the United States,
for the Southern District of New York.
W.H. TINSON, Printer and Stereotyper, 43 Centre Street.
* * * * *
TABLE OF CONTENTS.
PART I.
Preface, 7
The Use of the Blowpipe, 9
Utensils--The Blowpipe, 12
The Oil Lamp, 22
The Spirit Lamp, 23
Charcoal Support, 24
Platinum Supports, 26
Iron Spoons, 28
Glass Tubes, 28
Other Apparatus necessary, 31
THE REAGENTS, 34
Reagents of General Use, 34
Carbonate of Soda, 34
Hydrate of Baryta, 35
Bi-sulphate of Potassa, 35
Oxalate of Potassa, 36
Cyanide of Potassium, 36
Nitrate of Potassa, 37
Borax, 38
Microcosmic Salt, 39
Nitrate of Cobalt, 40
Tin, 41
Silica, 42
Test Papers, 42
ESPECIAL REAGENTS, 43
Boracic Acid, 43
Fluorspar, 43
Oxalate of Nickel, 43
Oxide of Copper, 43
Antimoniate of Potassa, 44
Silver Foil, 44
Nitroprusside of Sodium, 44
PART II.
Initiatory Analysis, 47
Examination with the Glass Bulb, 47
" in the Open Tube, 52
" upon Charcoal, 55
" in the Platinum Forceps, 61
" in the Borax Bead, 69
" in Microcosmic Salt, 72
Table I.--Colors of Beads of Borax and Microcosmic Salt, 75
Table II.--Behavior of Metallic Oxydes with Borax and
Microcosmic Salt, 85
Examinations with Carbonate of Soda, 103
PART III.
Special Reactions, 109
A.--METALLIC OXIDES:
First Group.--The Alkalies: Potassa, Soda, Ammonia, and Lithia, 110
Second Group.--The Alkaline Earths: Baryta, Strontia, Lime,
and Magnesia, 115
Third Group.--The Earths: Alumina, Glucina, Yttria, Thorina,
and Zirconia, 121
Fourth Group.--Cerium, Lanthanium, Didymium, Columbium,
Niobium, Pelopium, Titanium, Uranium, Vanadium, Chromium,
Manganese, 124
Fifth Group.--Iron, Cobalt, Nickel, 135
Sixth Group.--Zinc, Cadmium, Antimony, Tellurium, 140
Seventh Group.--Lead, Bismuth, Tin, 149
Eighth Group.--Mercury, Arsenic, 157
Ninth Group.--Copper, Silver, Gold, 161
Tenth Group.--Molybdenum, Osmium, 165
Eleventh Group.--Platinum, Palladium, Iridium, Rhodium,
Ruthenium, 167
Non-Metallic Substances, 168
Tabular Statement of the Reactions of Minerals before
the Blowpipe, 178
Carbon and Organic Minerals, 181
Potassa, 184
Soda, 186
Baryta and Strontia, 190
Lime, 192
Magnesia, 196
Alumina, 200
Silicates, 204
Uranium, 212
Iron, 214
Manganese, 222
Nickel and Cobalt, 226
Zinc, 232
Bismuth, 234
Lead, 238
Copper, 248
Antimony, 256
Arsenic, 260
Mercury, 262
Silver, 264
* * * * *
PREFACE.
It is believed the arrangement of the present work is superior to that
of many of its predecessors, as a vehicle for the facilitation of the
student's progress. While it does not pretend to any other rank than
as an introduction to the larger works, it is hoped that the
arrangement of its matter is such that the beginner may more readily
comprehend the entire subject of Blowpipe Analysis than if he were to
begin his studies by the perusal of the more copious works of
Berzelius and Plattner.
When the student shall have gone through these pages, and repeated the
various reactions described, then he will be fully prepared to enter
upon the study of the larger works. To progress through them will then
be but a comparatively easy task.
The arrangement of this little work has been such as the author and
his friends have considered the best that could be devised for the
purpose of facilitating the progress of the student. Whether we have
succeeded is left for the public to decide. The author is indebted to
several of his friends for valuable contributions and suggestions.
S.
CINCINNATI, _June, 1857_.
* * * * *
THE BLOWPIPE.
* * * * *
Part First.
THE USE OF THE BLOWPIPE.
Perhaps during the last fifty years, no department of chemistry has
been so enriched as that relating to analysis by means of the
Blowpipe.
Through the unwearied exertions of men of science, the use of this
instrument has arrived to such a degree of perfection, that we have a
right to term its use, "Analysis in the _dry_ way," in contradistinction
to analysis "in the _wet_ way." The manipulations are so simple and
expeditious, and the results so clear and characteristic, that the
Blowpipe analysis not only verifies and completes the results of
analysis in the wet way, but it gives in many cases direct evidences
of the presence or absence of many substances, which would not be
otherwise detected, but through a troublesome and tedious process,
involving both prolixity and time; for instance, the detection of
manganese in minerals.
Many substances have to go through Blowpipe manipulations before they
can be submitted to an analysis in the wet way. The apparatus and
reagents employed are compendious and small in number, so that they
can be carried easily while on scientific excursions, a considerable
advantage for mineralogists and metallurgists.
The principal operations with the Blowpipe may be explained briefly as
follows:
(_a._) By _Ignition_ is meant the exposure of a substance to such a
degree of heat, that it glows or emits light, or becomes red-hot. Its
greatest value is in the separation of a volatile substance from one
less volatile, or one which is entirely fixed at the temperature of
the flame. In this case we only take cognizance of the latter or fixed
substance, although in many instances we make use of ignition for the
purpose of changing the conditions of a substance, for example, the
sesquioxide of chromium (Cr^{2}O^{3}) in its insoluble modification;
and as a preliminary examination for the purpose of ascertaining
whether the subject of inquiry be a combination of an organic or
inorganic nature.
The apparatus used for this purpose are crucibles of platinum or
silver, platinum foil, a platinum spoon, platinum wire or tongs,
charcoal, glass tubes, and iron spoons.
(_b._) _Sublimation_ is that process by which we convert a solid
substance into vapor by means of a strong heat. These vapors are
condensed by refrigeration into the solid form. It may be termed a
distillation of a solid substance. Sublimation is of great consequence
in the detection of many substances; for instance, arsenic, antimony,
mercury, etc.
The apparatus used for the purposes of sublimation consist of glass
tubes closed at one end.
(_c._) _Fusion._--Many substances when exposed to a certain degree of
heat lose their solid form, and are converted into a liquid. Those
substances which do not become converted into the liquid state by
heat, are said to be infusible. It is a convenient classification to
arrange substances into those which are fusible with difficulty, and
those which are easily fusible. Very often we resort to fusion for the
purpose of decomposing a substance, or to cause it to enter into
other combinations, by which means it is the more readily detected. If
insoluble substances are fused with others more fusible (reagents) for
the purpose of causing a combination which is soluble in water and
acids, the operation is termed _unclosing_. These substances are
particularly the silicates and the sulphates of the alkaline earths.
The usual reagents resorted to for this purpose are carbonate of soda
(NaO, CO^{2}), carbonate of potash (KO, CO^{2}), or still better, a
mixture of the two in equal parts. In some cases we use the hydrate of
barytes (BaO, HO) and the bisulphate of potash (KO, 2SO^{3}). The
platinum spoon is generally used for this manipulation.
Substances are exposed to fusion for the purpose of getting a new
combination which has such distinctive characteristics that we can
class it under a certain group; or for the purpose of ascertaining at
once what the substance may be. The reagents used for this purpose are
borax (NaO, 2BrO^{3}) and the microcosmic salt (NaO, NH^{4}O, PO^{5},
HO). Charcoal and the platinum wire are used as supports for this kind
of operation.
(_d._) _Oxidation._--The chemical combination of any substance with
oxygen is termed _oxidation_, and the products are termed _oxides_. As
these oxides have qualities differing from those which are
non-oxidized, it therefore frequently becomes necessary to convert
substances into oxides; or, if they are such, of a lower degree, to
convert them into a higher degree of oxidation. These different states
of oxidation frequently present characteristic marks of identity
sufficient to enable us to draw conclusions in relation to the
substance under examination. For instance, the oxidation of manganese,
of arsenic, etc. The conditions necessary for oxidation, are high
temperature and the free admission of air to the substance.
If the oxidation is effected through the addition of a substance
containing oxygen (for instance, the nitrate or chlorate of potash)
and the heating is accompanied by a lively deflagration and crackling
noise, it is termed _detonation_. By this process we frequently
effect the oxidation of a substance, and thus we prove the presence or
the absence of a certain class of substances. For instance, if we
detonate (as it is termed by the German chemists) the sulphide of
antimony, or the sulphide of arsenic with nitrate of potash, we get
the nitrate of antimony, or the nitrate of arsenic. The salts of
nitric or chloric acid are determined by fusing them with the cyanide
of potassium, because the salts of these acids detonate.
(_e._) _Reduction._--If we deprive an oxidized substance of its
oxygen, we term the process _reduction_. This is effected by fusing
the substance under examination with another which possesses a greater
affinity for oxygen. The agents used for reduction are hydrogen,
charcoal, soda, cyanide of potassium, etc. Substances generally, when
in the unoxidized state, have such characteristic qualities, that they
cannot very readily be mistaken for others. For this reason, reduction
is a very excellent expedient for the purpose of discerning and
classifying many substances.
B. UTENSILS.
We shall give here a brief description of the most necessary apparatus
used for analysis in the dry way, and of their use.
_The Blowpipe_ is a small instrument, made generally out of brass,
silver, or German silver, and was principally used in earlier times
for the purpose of soldering small pieces of metals together. It is
generally made in the form of a tube, bent at a right angle, but
without a sharp corner. The largest one is about seven inches long,
and the smallest about two inches. The latter one terminates with a
small point, with a small orifice. The first use of the blowpipe that
we have recorded is that of a Swedish mining officer, who used it in
the year 1738 for chemical purposes, but we have the most meagre
accounts of his operations. In 1758 another Swedish mining officer, by
the name of Cronstedt, published his "Use of the Blowpipe in
Chemistry and Mineralogy," translated into English, in 1770, by Van
Engestroem. Bergman extended its use, and after him Ghan and the
venerable Berzelius (1821). The blowpipe most generally used in
chemical examinations is composed of the following parts: (_Fig._ 1.)
A is a little reservoir made air-tight by grinding the part B into it.
This reservoir serves the purpose of retaining the moisture with which
the air from the mouth is charged. A small conical tube is fitted to
this reservoir. This tube terminates in a fine orifice. As this small
point is liable to get clogged up with soot, etc., it is better that
it should be made of platinum, so that it may be ignited. Two of these
platinum tubes should be supplied, differing in the size of the
orifice, by which a stronger or lighter current of flame may be
projected from it. Metals, such as brass or German silver, are very
liable to become dirty through oxidation, and when placed between the
lips are liable to impart a disagreeable taste. To avoid this, the top
of the tube must be supplied with a mouthpiece of ivory or horn C. The
blowpipe here represented is the one used by Ghan, and approved by
Berzelius. The trumpet mouthpiece was adopted by Plattner; it is
pressed upon the lips while blowing, which is less tiresome than
holding the mouthpiece between the lips, although many prefer the
latter mode.
[Illustration: Fig. 1]
Dr. Black's blowpipe is as good an instrument and cheaper. It
consists of two tubes, soldered at a right angle; the larger one, into
which the air is blown, is of sufficient capacity to serve as a
reservoir.
A chemist can, with a blowpipe and a piece of charcoal, determine many
substances without any reagents, thus enabling him, even when
travelling, to make useful investigations with means which are always
at his disposal. There are pocket blowpipes as portable as a pencil
case, such as Wollaston's and Mitscherlich's; these are objectionable
for continued use as their construction requires the use of a metallic
mouthpiece. Mr. Casamajor, of New York, has made one lately which has
an ivory mouthpiece, and which, when in use, is like Dr. Black's.
[Illustration: Fig. 2]
The length of the blowpipe is generally seven or eight inches, but
this depends very much upon the visual angle of the operators. A
short-sighted person, of course, would require an instrument of less
length than would suit a far-sighted person.
The purpose required of the blowpipe is to introduce a fine current of
air into the flame of a candle or lamp, by which a higher degree of
heat is induced, and consequently combustion is more rapidly
accomplished.
By inspecting the flame of a candle burning under usual circumstances,
we perceive at the bottom of the flame a portion which is of a light
blue color (_a b_), _Fig._ 2, which gradually diminishes in size
as it recedes from the wick, and disappears when it reaches the
perpendicular side of the flame. In the midst of the flame there is a
dark nucleus with a conical form (_c_). This is enveloped by the
illuminating portion of the flame (_d_). At the exterior edge of the
part _d_ we perceive a thin, scarcely visible veil, _a, e, e_, which
is broader near the apex of the flame. The action of the burning
candle may be thus explained. The radiant heat from the flame melts
the tallow or wax, which then passes up into the texture of the wick
by capillary attraction until it reaches the glowing wick, where the
heat decomposes the combustible matter into carbonated hydrogen
(C^{4}H^{4}), and into carbonic oxide (CO).
While these gases are rising in hot condition, the air comes in
contact with them and effects their combustion. The dark portion, _c_,
of the flame is where the carbon and gases have not a sufficiency of
air for their thorough combustion; but gradually they become mixed
with air, although not then sufficient for complete combustion. The
hydrogen is first oxidized or burnt, and then the carbon is attacked
by the air, although particles of carbon are separated, and it is
these, in a state of intense ignition, which produce the illumination.
By bringing any oxidizable substance into this portion of the flame,
it oxidizes very quickly in consequence of the high temperature and
the free access of air. For that reason this part of the flame is
termed the oxidizing flame, while the illuminating portion, by its
tendency to abstract oxygen for the purpose of complete combustion,
easily reduces oxidated substances brought into it, and it is,
therefore, called the flame of reduction. In the oxidizing flame, on
the contrary, all the carbon which exists in the interior of the flame
is oxidized into carbonic acid (CO^{2}) and carbonic oxide (CO), while
the blue color of the cone of the flame is caused by the complete
combustion of the carbonic oxide. These two portions of the flame--the
oxidizing and the reducing--are the principal agents of blowpipe
analysis.
If we introduce a fine current of air into a flame, we notice the
following: The air strikes first the dark nucleus, and forcing the
gases beyond it, mixes with them, by which oxygen is mingled freely
with them. This effects the complete combustion of the gases at a
certain distance from the point of the blowpipe. At this place the
flame has the highest temperature, forming there the point of a blue
cone. The illuminated or reducing portion of the flame is enveloped
outside and inside by a very hot flame, whereby its own temperature is
so much increased that in this reduction-flame many substances will
undergo fusion which would prove perfectly refractory in a common
flame. The exterior scarcely visible part loses its form, is
diminished, and pressed more to a point, by which its heating power is
greatly increased.
_The Blast of Air._--By using the blowpipe for chemical purposes, the
effect intended to be produced is an uninterrupted steady stream of
air for many minutes together, if necessary, without an instant's
cessation. Therefore, the blowing can only be effected with the
muscles of the cheeks, and not by the exertion of the lungs. It is
only by this means that a steady constant stream of air can be kept
up, while the lungs will not be injured by the deprival of air. The
details of the proper manner of using the blowpipe are really more
difficult to describe than to acquire by practice; therefore the pupil
is requested to apply himself at once to its practice, by which he
will soon learn to produce a steady current of air, and to distinguish
the different flames from each other. We would simply say that the
tongue must be applied to the roof of the mouth, so as to interrupt
the communication between the passage of the nostrils and the mouth.
The operator now fills his mouth with air, which is to be passed
through the pipe by compressing the muscles of the cheeks, while he
breathes through the nostrils, and uses the palate as a valve. When
the mouth becomes nearly empty, it is replenished by the lungs in an
instant, while the tongue is momentarily withdrawn from the roof of
the mouth. The stream of air can be continued for a long time, without
the least fatigue or injury to the lungs. The easiest way for the
student to accustom himself to the use of the blowpipe, is first to
learn to fill the mouth with air, and while the lips are kept firmly
closed to breathe freely through the nostrils. Having effected this
much, he may introduce the mouthpiece of the blowpipe between his
lips. By inflating the cheeks, and breathing through the nostrils, he
will soon learn to use the instrument without the least fatigue. The
air is forced through the tube against the flame by the action of the
muscles of the cheeks, while he continues to breathe without
interruption through the nostrils. Having become acquainted with this
process, it only requires some practice to produce a steady jet of
flame. A defect in the nature of the combustible used, as bad oil,
such as fish oil, or oil thickened by long standing or by dirt, dirty
cotton wick, or an untrimmed one, or a dirty wickholder, or a want of
steadiness of the hand that holds the blowpipe, will prevent a steady
jet of flame. But frequently the fault lies in the orifice of the jet,
or too small a hole, or its partial stoppage by dirt, which will
prevent a steady jet of air, and lead to difficulty. With a good
blowpipe the air projects the entire flame, forming a horizontal, blue
cone of flame, which converges to a point at about an inch from the
wick, with a larger, longer, and more luminous flame enveloping it,
and terminating to a point beyond that of the blue flame.
To produce an efficient flame of oxidation, put the point of the
blowpipe into the flame about one third the diameter of the wick, and
about one twelfth of an inch above it. This, however, depends upon
the size of the flame used. Blow strong enough to keep the flame
straight and horizontal, using the largest orifice for the purpose.
Upon examining the flame thus produced, we will observe a long, blue
flame, _a b_, Fig. 3, which letters correspond with the same letters
in Fig. 2. But this flame has changed its form, and contains all the
combustible gases. It forms now a thin, blue cone, which converges to
a point about an inch from the wick. This point of the flame possesses
the highest intensity of temperature, for there the combustion of the
gases is the most complete. In the original flame, the hottest part
forms the external envelope, but here it is compressed more into a
point, forming the cone of the blue flame, and likewise an envelope of
flame surrounding the blue one, extending beyond it from _a_ to _c_,
and presenting a light bluish or brownish color. The external flame
has the highest temperature at _d_, but this decreases from _d_ to
_c_.
[Illustration: Fig. 3]
If there is a very high temperature, the oxidation is not effected so
readily in many cases, unless the substance is removed a little from
the flame; but if the heat be not too high, it is readily oxidized in
the flame, or near its cone. If the current of air is blown too
freely or violently into the flame, more air is forced there than is
sufficient to consume the gases. This superfluous air only acts
detrimentally, by cooling the flame.
In general the operation proceeds best when the substance is kept at a
dull red heat. The blue cone must be kept free from straggling rays of
the yellow or reduction flame. If the analysis be effected on
charcoal, the blast should not be too strong, as a part of the coal
would be converted into carbonic oxide, which would act
antagonistically to the oxidation. The oxidation flame requires a
steady current of air, for the purpose of keeping the blue cone
constantly of the same length. For the purpose of acquiring practice,
the following may be done: Melt a little molybdenic acid with some
borax, upon a platinum wire, about the sixteenth of an inch from the
point of the blue cone. In the pure oxidation flame, a clear yellowish
glass is formed; but as soon as the reduction flame reaches it, or the
point of the blue cone touches it, the color of the bead changes to a
brown, which, finally, after a little longer blowing, becomes quite
dark, and loses its transparency. The cause of this is, that the
molybdenic acid is very easily reduced to a lower degree of oxidation,
or to the oxide of molybdenum. The flame of oxidation will again
convert this oxide into the acid, and this conversion is a good test
of the progress of the student in the use of the blowpipe. In cases
where we have to separate a more oxidizable substance from a less one,
we use with success the blue cone, particularly if we wish to
determine whether a substance has the quality, when submitted to heat
in the blue cone, of coloring the external flame.
A good _reduction_ flame can be obtained by the use of a small orifice
at the point of the blowpipe. In order to produce such a flame, hold
the point of the blowpipe higher above the wick, while the nozzle must
not enter the flame so far as in the production of the oxidation
flame. The point of the blowpipe should only touch the flame, while
the current of air blown into it must be stronger than into the
oxidation flame. If we project a stream, in the manner mentioned, into
the flame, from the smaller side of the wick to the middle, we shall
perceive the flame changed to a long, narrow, luminous cone, _a b_,
Fig. 4, the end _a_ of which is enveloped by the same dimly visible
blueish colored portion of the flame _a, c_, which we perceive in the
original flame, with its point at _c_. The portion close above the
wick, presenting the dull appearance, is occasioned by the rising
gases which have not supplied to them enough oxygen to consume them
entirely. The hydrogen is consumed, while the carbon is separated in a
state of bright ignition, and forms the internal flame.
[Illustration: Fig. 4]
Directly above the wick, the combustion of the gases is least
complete, and forms there likewise, as is the case in the free flame,
a dark blue nucleus _d_.
If the oxide of a metal is brought into the luminous portion of the
flame produced as above, so that the flame envelopes the substance
perfectly, the access of air is prevented. The partially consumed
gases have now a strong affinity for oxygen, under the influence of
the intense heat of that part of the flame. The substance is thus
deprived of a part, or the whole, of its oxygen, and becomes _reduced_
according to the strength of the affinity which the substance itself
has for oxygen. If the reduction of a substance is undertaken on
platinum, by fusion with a flux, and if the oxide is difficult to
reduce, the reduction will be completely effected only in the luminous
part of the flame. But if a substance be reduced on charcoal, the
reduction will take place in the blue part of the flame, as long as
the access of air is cut off; but it is the luminous part of the flame
which really possesses the greatest reducing power.
The following should be observed in order to procure a good reduction
flame:
The wick should not be too long, that it may make a smoke, nor
too short, otherwise the flame will be too small to produce a
heat strong enough for reduction.
The wick must be free from all loose threads, and from
charcoal.
The blast should be continued for a considerable time without
intermission, otherwise reduction cannot be effected.
For the purpose of acquiring practice, the student may fuse the oxide
of manganese with borax, upon a platinum wire, in the oxidation flame,
when a violet-red glass will be obtained; or if too much of the oxide
be used, a glass of a dark color and opaque will be obtained. By
submitting this glass to the reduction flame, it will become colorless
in correspondence to the perfection with which the flame is produced.
Or a piece of tin may be fused upon charcoal, and kept in that state
for a considerable time, while it presents the appearance of a bright
metal on the surface. This will require dexterity in the operator;
for, if the oxidation flame should chance to touch the bright metal
only for a moment, it is coated with an infusible oxide.
COMBUSTION.--Any flame of sufficient size can be used for blowpipe
operations. It may be either the flame of a candle of tallow or wax,
or the flame of a lamp. The flame of a wax candle, or of an oil lamp
is most generally used. Sometimes a lamp is used filled with a
solution of spirits of turpentine in strong alcohol. If a candle is
used, it is well to cut the wick off short, and to bend the wick a
little toward the substance experimented upon. But candles are not the
best for blowpipe operations, as the radiant heat, reflecting from the
substance upon the wax or tallow, will cause it to melt and run down
the side of the candle; while again, candles do not give heat enough.
The lamp is much the most desirable. The subjoined figure, from
Berzelius, is perhaps the best form of lamp. It is made of japanned
tin-plate, about four inches in length, and has the form and
arrangement represented in Fig. 5. K is the lamp, fastened on the
stand, S, by a screw, C, and is movable upwards or downwards, as
represented in the figure. The posterior end of the lamp may be about
one inch square, and at its anterior end, E, about three-quarters of
an inch square. The under side of this box may be round, as seen in
the figure. The oil is poured into the orifice, A, which has a cap
screwed over it. C' is a wickholder for a flat lamp-wick. _a_ is a
socket containing the wick, which, when not in use, is secured from
dirt by the cap. The figures B and _a'_ give the forms of the cap and
socket. The best combustible for this lamp is the refined rape-seed
oil, or pure sweet oil. When this lamp is in use, there must be no
loose threads, or no charcoal on the wick, or these will produce a
smoky flame. The wick, likewise, should not be pulled up too high, as
the same smoky flame would be produced.
[Illustration: Fig. 5]
THE SPIRIT-LAMP.--This is a short, strong glass lamp, with a cap, B,
Fig. 6, fitted to it by grinding, to prevent the evaporation of the
alcohol. The neck _a_ contains a tube C, made of silver, or of tin
plate, and which contains the wick. Brass would not answer so well
for this tube, as the spirits would oxidize it, and thus impart color
to the flame. The wickholder must cover the edge of the neck, but not
fit tight within the tube, otherwise, by its expansion, it will break
the glass. It is not necessary that alcohol, very highly rectified,
should be burnt in this lamp, although if too much diluted with water,
enough heat will not be given out. Alcohol of specific gravity 0.84 to
0.86 is the best.
[Illustration: Fig. 6]
This lamp is generally resorted to by blowpipe analysts, for the
purpose of experiments in glass apparatus, as the oily combustibles
will coat the glass with soot. Some substances, when exposed to the
dark part of the flame, become reduced and, _in statu nascendi_,
evaporated; but by passing through the external part of the flame,
they become oxidized again, and impart a color to the flame. The
spirit flame is the most efficient one for the examination of
substances the nature of which we wish to ascertain through color
imparted to the flame, as that of the spirit-lamp being colorless, is,
consequently, most easily and thoroughly recognized by the slightest
tinge imparted to it.
It is necessary that in operating with such minute quantities of
substances as are used in blowpipe analysis, that they should have
some appropriate support. In order that no false results may ensue, it
is necessary that the supports should be of such a nature that they
will not form a chemical combination with the substance while it is
exposed to fusion or ignition. Appropriate supports for the different
blowpipe experiments are charcoal, platinum instruments, and glass
tubes.
(_a._) _Charcoal._--The value of charcoal as a support may be stated
as follows:
1. The charcoal is infusible, and being a poor conductor of
heat, a substance can be exposed to a higher degree of heat
upon it than upon any other substance.
2. It is very porous, and therefore allows easily fusible
substances (such as alkalies and fluxes) to pass into it,
while other substances less fusible, such as metals, to remain
unabsorbed.
3. It has likewise a great reducing power.
The best kind of charcoal is that of pinewood, linden, willow, or
alderwood, or any other soft wood. Coal from the firwood sparkles too
freely, while that of the hard woods contains too much iron in its
ashes. Smooth pieces, free from bark and knots, should be selected. It
should be thoroughly burnt, and the annual rings or growths should be
as close together as possible.
If the charcoal is in masses, it should be sawed into pieces about six
inches in length by about two inches broad, but so that the
year-growths run perpendicular to the broadest side, as the other
sides, by their unequal structure, burn unevenly.
That the substance under examination may not be carried off by the
blast, small conical concavities should be cut in the broad side of
the charcoal, between the year-growths, with a conical tube of tin
plate about two or three inches long, and one quarter of an inch at
one end, and half an inch at the other. These edges are made sharp
with a file. The widest end of this charcoal borer is used for the
purpose of making cavities for cupellation.
In places where the proper kind of charcoal is difficult to procure,
it is economical to cut common charcoal into pieces about an inch
broad, and the third of an inch thick. In each of these little pieces
small cavities should be cut with the small end of the borer. When
these pieces of charcoal are required for use, they must be fastened
to a narrow slip of tin plate, one end of which is bent into the form
of a hook, under which the plate of charcoal is pushed.
In general, we use the charcoal support where we wish to reduce
metallic oxides, to prevent oxidation, or to test the fusibility of a
substance. There is another point to which we would direct the
student. Those metals which are volatile in the reduction flame,
appear as oxides in the oxidation flame. These oxides make sublimates
upon the charcoal close in the vicinity of the substance, or where it
rested, and by their peculiar color indicate pretty correctly the
species of minerals experimented upon.
(_b._) _Platinum Supports._--The metal platinum is infusible in the
blowpipe flame, and is such a poor conductor of heat that a strip of
it may be held close to that portion of it which is red hot without
the least inconvenience to the fingers. It is necessary that the
student should be cognizant of those substances which would not be
appropriate to experiment upon if placed on platinum. Metals should
not be treated upon platinum apparatus, nor should the easily
reducible oxides, sulphides, nor chlorides, as these substances will
combine with the platinum, and thus render it unfit for further use in
analysis.
(_c._) _Platinum Wire._--As the color of the flame cannot be well
discerned when the substance is supported upon charcoal, in
consequence of the latter furnishing false colors, by its own
reflection, to the substances under examination, we use platinum wire
for that purpose, when we wish to examine those substances which give
indications by the peculiar color which they impart to fluxes. The
wire should be about as thick as No. 16 or 18 wire, or about 0.4
millimetre, and cut into pieces about from two and a half to three
inches in length. The end of each piece is crooked. In order that
these pieces should remain clear of dirt, and ready for use, they
should be kept in a glass of water. To use them, we dip the wetted
hooked end into the powdered flux (borax or microcosmic salt) some of
which will adhere, when we fuse it in the flame of the blowpipe to a
bead. This bead hanging in the hook, must be clear and colorless.
Should there not adhere a sufficient quantity of the flux in the first
trial to form a bead sufficiently large, the hook must be dipped a
second time in the flux and again submitted to the blowpipe flame. To
fix the substance to be examined to the bead, it is necessary, while
the latter is hot, to dip it in the powdered substance. If the hook is
cold, we moisten the powder a little, and then dip the hook into it,
and then expose it to the oxidation flame, by keeping it exposed to a
regular blast until the substance and the flux are fused together, and
no further alteration is produced by the flame.
The platinum wire can be used except where reduction to the metallic
state is required. Every reduction and oxidation experiment, if the
results are to be known by the color of the fluxes, should be effected
upon platinum wire. At the termination of the experiment or
investigation, if it be one, to, clean the wire, place it in water,
which will dissolve the bead.
(_d._) _Platinum Foil._--For the heating or fusing of a substance,
whereby its reduction would be avoided, we use platinum foil as a
support. This foil should be of the thickness of good writing paper,
and from two and a half to three inches long, by about half an inch
broad, and as even and smooth as possible. If it should become injured
by long use, cut the injured end off, and if it should prove too short
to be held with the fingers, a pair of forceps may be used to grasp
it, or it may be placed on a piece of charcoal.
(_e._) _Platinum Spoon._--When we require to fuse substances with the
acid sulphate of potash, or to oxidize them by detonation with nitrate
of potash, whereby we wish to preserve the oxide produced, we
generally use a little spoon of platinum, about from nine to fifteen
millimetres[1] in diameter, and shaped as represented in Fig. 7. The
handle of this spoon is likewise of platinum, and should fit into a
piece of cork, or be held with the forceps.
[1] The French millimetre is about the twenty-fifth part of an
English inch.
[Illustration: Fig. 7.]
(_f._) _Platinum Forceps or Tongs._--We frequently are necessitated to
examine small splinters of metals or minerals directly in the blowpipe
flame. These pieces of metallic substances are held with the forceps
or tongs represented as in Fig. 8, where _ac_ is formed of steel, and
_aa_ are platinum bars inserted between the steel plates. At _bb_ are
knobs which by pressure so separate the platinum bars _aa_, that any
small substance can be inserted between them.
[Illustration: Fig. 8.]
(_g._) _Iron Spoons._--For a preliminary examination iron spoons are
desirable. They may be made of sheet iron, about one-third of an inch
in diameter, and are very useful in many examinations where the use of
platinum would not be desirable.
(_h._) _Glass Tubes._--For the separation and recognition of volatile
substances before the blowpipe flame, we use glass tubes. These should
be about one-eighth of an inch in diameter, and cut into pieces about
five or six inches in length. These tubes should have both ends open.
Tubes are of great value in the examination of volatile substances
which require oxidizing or roasting, and heating with free access of
air. Also to ascertain whether a substance under examination will
sublimate volatile matter of a certain appearance. Such substances are
selenium, sulphur, arsenic, antimony, and tellurium. These substances
condense on a cool part of the tube, and they present characteristic
appearances, or they may be recognized by their peculiar smell. These
tubes must be made of the best kind of glass, white and difficult of
fusion, and entirely free from lead. The substance to be examined must
be put in the tube near one end, and exposed to the flame of the
blowpipe. The end containing the substance must be held lower than the
other end, and must be moved a little over the spirit-lamp before a
draught of air is produced through the tube. It is a good plan to have
a number of these tubes on hand. After having used a tube we cut off
that end of it which contained the substance, with a file, and clean
it from the sublimate, either by heating it over the spirit-lamp, or
with a piece of paper wound around a wire. It sometimes happens that
the substance falls out of the tube before it becomes sufficiently
melted to adhere to the glass. To obviate this, we bend the tube not
far from the end, at an obtuse angle, and place the substance in the
angle, whereby the tube may be lowered as much as necessary. Fig. 9
will give the student a comprehension of the processes described, and
of the manner of bending the tubes.
[Illustration: Fig. 9.]
(_i._) _Glass Tubes closed at one End._--If we wish to expose volatile
substances to heat, with the exclusion of air as much as possible, or
to ascertain the contents of water, or other volatile fluids, or for
the purpose of heating substances which will decrepitate, we use glass
tubes closed at one end. These tubes must be about one-eighth of an
inch wide, and from two to three inches in length. They should be made
of white glass, difficult of fusion, and free from lead. They should
be closed at one end, as figured in the margin, Fig. 10.
[Illustration: Fig. 10.]
When a substance is to be examined for the purpose of ascertaining
whether it contains combustible matter, as sulphur or arsenic, and
where we wish to avoid oxidation, we use these tubes without extending
the closed end, in order that there may be as little air admitted as
possible, as is represented in tube B. But when a substance to be
examined is to be tested for water, or other incombustible volatile
matters, we employ tubes with little bulbs blown at one end, such as
represented at tube A. Here there is room for a circulation of air at
the bottom of the tube, by which the volatile matter rises more
easily. In some cases, it is necessary to draw the closed end out to a
fine point, as in the tubes C and D. Either one or the other of these
tubes is employed, depending upon the nature of the substance used.
The sublimates condense at the upper part of the tube _a_, and can be
there examined and recognized. These tubes, before being used, must be
thoroughly dried and cleaned. In experimenting with them, they should
not be exposed at once to the hottest part of the flame, but should be
submitted to the heat gradually. If the substance is of such a nature
that it will sublime at a low heat, the tube should be held more
horizontal, while a higher heat is attained by bringing the tube to a
more vertical position.
VARIOUS APPARATUS NECESSARY.
_Edulcorator or Washing Bottle._--Take a glass bottle of the capacity
of about twelve ounces, and close the mouth of it very tight with a
cork, through which a short glass tube is fitted airtight. The
external end of this tube is drawn out to a point, with a very fine
orifice. The bottle should be filled about half full of water. By
blowing air into the bottle through the tube, and then turning it
downwards, the compressed air will expel a fine stream of water
through the fine orifice with considerable force. We use this washing
bottle, Fig. 11, for the purpose of rinsing the small particles of
coal from the reduced metals.
[Illustration: Fig. 11.]
_Agate Mortar and Pestle._--This mortar is used for the purpose of
pulverizing hard substances, and for mixing fluxes. As this mortar
will not yield to abrasion, there is no danger of any foreign matter
becoming mixed with the substance pulverized in it. It should be
cleaned after use with pumice stone. Steel mortars are very useful for
the pulverization of hard bodies; but for all those substances which
require great care in their analysis, and which can be obtained in
very minute quantity, the agate mortar alone should be used.
A _hammer_ made of steel is necessary. This should have the edge
square.
A small _anvil_, polished on the surface, is also required. It is
frequently used to test the malleability of metals.
A _knife_, for the purpose of ascertaining the hardness of minerals.
The student should also be provided with several three-edged files,
and likewise with some flat ones.
A _microscope_, an instrument with two lenses, or with such a
combination of lenses, that they may be used double or single, is
frequently necessary for the examination of blowpipe experiments, or
the reaction of the fluxes. Common lenses, howsoever cheap they may
be, are certainly not recommended. A microscope with achromatic lenses
can now be purchased so cheap that there is no longer any necessity of
procuring one with the common lens. Besides, there is no reliability
whatever to be placed in the revelations of the common lens; while on
the contrary, the deceptive appearances which minute objects assume
beneath such lenses are more injurious than otherwise. A small cheap
set of magnifying glasses are all that is required for the purpose of
blowpipe analysis, Fig. 12.
[Illustration: Fig. 12.]
A small _magnet_ should be kept on hand, for the purpose of testing
reduced metals.
_Nippers_, for the purpose of breaking off pieces of minerals for
analysis, without injuring the entire piece, are indispensable, Fig
13.
[Illustration: Fig. 13.]
A pair of _scissors_ is required to trim the wick of the and for the
trimming of the edge of platinum foil.
A small _spatula_ should be kept for the purpose of mixing substances
with fluxes.
THE REAGENTS.
Those substances which possess the property of acting upon other
substances, in such a characteristic manner that they can be
recognized, either by their color, or by their effervescence, or by
the peculiar precipitation produced, are termed _reagents_. The
phenomena thus produced is termed _reaction_. We use those reagents,
or _tests_, for the purpose of ascertaining the presence or the
absence of certain substances, through the peculiar phenomena produced
when brought in contact with them.
The number of reagents employed in blowpipe analysis is not great, and
therefore we shall here give a brief description of their preparation
and use. It is indispensably necessary that they should be chemically
pure, as every admixture of a foreign substance would only produce a
false result. Some of them have a strong affinity for water, or are
deliquescent, and consequently absorb it greedily from the air. These
must be kept in glass bottles, with glass stoppers, fitted air-tight
by grinding.
A. REAGENTS OF GENERAL USE.
1. _Carbonate of Soda._--(NaO, CO^{2}) Wash the bicarbonate of soda
(NaO, 2CO^{2}) upon a filter, with cold water, until the filtrate
ceases to give, after neutralization with diluted nitric acid
(NO^{5}), a precipitate with nitrate of baryta, (BaO, NO^{5}), or
nitrate of silver, (AgO, NO^{5}). That left upon the filter we make
red hot in a platinum, silver, or porcelain dish. One atom of carbonic
acid is expelled, and the residue is carbonate of soda.
A solution of soda must not be changed by the addition of sulphide of
ammonium. And when neutralized with hydrochloric acid, and evaporated
to dryness, and again dissolved in water, there must be no residue
left.
Carbonate of soda is an excellent agent in reduction, in consequence
of its easy fusibility, whereby it causes the close contact of the
oxides with the charcoal support, so that the blowpipe flame can reach
every part of the substance under examination.
For the decomposition and determination of insoluble substances,
particularly the silicates, carbonate of soda is indispensable. But
for the latter purpose, we use with advantage a mixture of ten parts
of soda and thirteen parts of dry carbonate of potash, which mixture
fuses more easily than the carbonate of soda alone.
2. _Hydrate of Baryta_ (BaO, HO).--This salt is used sometimes for the
detection of alkalies in silicates. Mix one part of the substance with
about four parts of the hydrate of baryta, and expose it to the
blowpipe flame. The hydrate of baryta combines with the silicic acid,
and forms the super-basic silicate of baryta, while the oxides become
free. The fused mass must be dissolved in hydrochloric acid, which
converts the oxides into chlorides. Evaporate to dryness, and dissolve
the residue in water. The silicic acid remains insoluble.
The hydrate of baryta is prepared by mixing six parts of finely
powdered heavy-spar (BaO, SO_{3}) with one part of charcoal and one
and a half parts of wheat flour, and exposing this mixture in a
Hessian crucible with a cover to a strong and continuous red heat. The
cooled chocolate-brown mass must be boiled with twenty parts of water,
and, while boiling, there must be added the oxide of copper in
sufficient quantity, or until the liquid will not impart a black color
to a solution of acetate of lead (PbO, [=]A). The liquid must be
filtered while hot, and as it cools the hydrate of baryta appears in
crystals. These crystals must be washed with a little cold water, and
then heated at a low temperature in a porcelain dish until the crystal
water is expelled. The hydrate of baryta melts by a low red heat
without losing its water of hydration.
3. _Bisulphate of Potassa_ (KO, 2SO^{3}).--At a red heat the half of
the sulphuric acid of this salt becomes free, and thus separates and
expels volatile substances, by which we can recognize lithium, boracic
acid, nitric acid, fluoric acid, bromine, iodine, chlorine; or it
decomposes and reveals some other compounds, as, for instance, the
salts of the titanic, tantalic and tungstic acids. The bisulphate of
potash is also used for the purpose of converting a substance into
sulphate, or to free it at once from certain constituents. These
sulphates are dissolved in water, by which we are enabled to effect
the separation of its various constituents.
PREPARATION.--Two parts of coarsely powdered sulphate of potash are
placed in a porcelain crucible, and one part of pure sulphuric acid is
poured over it. Expose this to heat over the spirit-lamp, until the
whole becomes a clear liquid. The cooled mass must be of a pure white
color, and may be got out of the crucible by inverting it. It must be
kept in a fine powder.
4. _Oxalate of Potassa_ (KO, [=]O).--Dissolve bioxalate of potash in
water, and neutralize with carbonate of potash. Evaporate the solution
at a low heat to dryness, stirring constantly towards the close of the
operation. The dry residue is to be kept in the form of a powder.
The oxalate of potash, at a low red heat, eliminates a considerable
quantity of carbonic oxide, which, having a strong affinity for
oxygen, with which it forms carbonic acid, it is therefore a powerful
agent of reduction. It is in many cases preferable to carbonate of
soda.
5. _Cyanide of Potassium_ (Cy, K).--In the dry method of analysis,
this salt is one of the most efficient agents for the reduction of
metallic oxides. It separates not only the metals from their oxygen
compounds, but likewise from their sulphur compounds, while it is
converted through the action of the oxygen into carbonate of potash,
or, in the latter case, combines with the sulphur and forms the
sulphureted cyanide of potassium. This separation is facilitated by
its easy fusibility. But in many cases it melts too freely, and
therefore it is better to mix it, for blowpipe analysis, with an equal
quantity of soda. This mixture has great powers of reduction, and it
is easily absorbed by the charcoal, while the globules of reduced
metal are visible in the greatest purity.
PREPARATION.--Deprive the ferrocyanide of potassium (2KCy + FeCy) of
its water by heating it over the spirit-lamp in a porcelain dish. Mix
eight parts of this anhydrous salt with three parts of dry carbonate
of potash, and fuse the mixture by a low red heat in a Hessian, or
still better, in an iron crucible with a cover, until the mass flows
quiet and clear, and a sample taken up with an iron spatula appears
perfectly white. Pour the clear mass out into a china or porcelain
dish or an iron plate, but with caution that the fine iron particles
which have settled to the bottom, do not mix with it. The white fused
mass must be powdered, and kept from the air. The cyanide of potassium
thus prepared, contains some of the cyanate of potassa, but the
admixture does not deteriorate it for blowpipe use. It must be
perfectly white, free from iron, charcoal, and sulphide of potassium.
The solution of it in water must give a white precipitate with a
solution of lead, and when neutralized with hydrochloric acid, and
evaporated to dryness, it must not give an insoluble residue by
dissolving it again in water.
6. _Nitrate of Potassa, Saltpetre_ (KO, NO^{5}).--Saturate boiling
water with commercial saltpetre, filter while hot in a beaker glass,
which is to be placed in cold water, and stir while the solution is
cooling. The greater part of the saltpetre will crystallize in very
fine crystals. Place these crystals upon a filter, and wash them with
a little cold water, until a solution of nitrate of silver ceases to
exhibit any reaction upon the filtrate. These crystals must be dried
and powdered.
Saltpetre, when heated with substances easy of oxidation, yields its
oxygen quite readily, and is, therefore, a powerful means of
oxidation. In blowpipe analysis, we use it particularly to convert
sulphides (as those of arsenic, antimony, &c.) into oxides and acids.
We furthermore use saltpetre for the purpose of producing a complete
oxidation of small quantities of metallic oxides, which oxidize with
difficulty in the oxidation flame, so that the color of the bead, in
its highest state of oxidation, shall be visible, as for instance,
manganese dissolved in the microcosmic salt.
7. _Biborate of soda, borax_--(NaO + 2BO^{3}).--Commercial borax is
seldom pure enough for a reagent. A solution of borax must not give a
precipitate with carbonate of potassa; or, after the addition of
dilute nitric acid, it must remain clear upon the addition of nitrate
of silver, or nitrate of baryta. Or a small piece of the dry salt,
fused upon a platinum wire, must give a clear and uncolored glass, as
well in the oxidation flame as in the reduction flame. If these tests
indicate a foreign admixture, the borax must be purified by
re-crystallization. These crystals are washed upon a filter, dried,
and heated, to expel the crystal water, or until the mass ceases to
swell up, and it is reduced to powder.
Boracic acid is incombustible, and has a strong affinity for oxides
when fused with them; therefore, it not only directly combines with
oxides, but it expels, by fusion, all other volatile acids from their
salts. Furthermore, boracic acid promotes the oxidation of metals and
sulphur, and induces haloid compounds, in the oxidation flame, to
combine with the rising oxides. Borates thus made, melt generally by
themselves; but admixed with borate of soda, they fuse much more
readily, give a clear bead. Borax acts either as a flux, or through
the formation of double salts.
In borax, we have the action of free boracic acid, as well as borate
of soda, and for that reason it is an excellent reagent for blowpipe
analysis.
All experiments in which borax is employed should be effected upon
platinum wire. The hook of the wire should be heated red hot, and then
dipped into the powdered borax. This should be exposed to the
oxidation flame, when it will be fused to a bead, which adheres to the
hook. This should be then dipped into the powdered substance, which
will adhere to it if it is hot; but if the bead is cool, it must be
previously moistened. Expose this bead to the oxidation flame until it
ceases to change, then allow it to cool, when it should be exposed to
the reduction flame. Look for the following in the oxidation flame:
(1.) Whether the heated substance is fused to a clear bead or
not, and whether the bead remains transparent after cooling. The
beads of some substances, for instance those of the alkaline
earths, are clear while hot; but upon cooling, are milk-white and
enamelled. Some substances give a clear bead when heated and when
cold, but appear enamelled when heated intermittingly or with a
flame which changes often from oxidation to reduction, or with an
unsteady flame produced by too strong a blast. The reason is an
incomplete fusion, while from the basic borate compound a part of
the base is separated. As the boracic acid is capable of
dissolving more in the heat, a bead will be clear while hot,
enamelled when cold, as a part in the latter instance will become
separated.
(2.) Whether the substance dissolves easily or not, and whether
it intumesces from arising gases.
(3.) Whether the bead, when exposed to the oxidation flame,
exhibits any color, and whether the color remains after the bead
shall have cooled, or whether the color fades.
(4.) Whether the bead exhibits any other reaction in the
reduction flame.
The bead should not be overcharged with the substance under
examination, or it will become colored so deeply as not to present any
transparency, or the color light enough to discern its hue.
8. _Microcosmic Salt--Phosphate of Soda and Ammonia_--(NaO, NH^{4}O +
PO^{5}).--Dissolve six parts of phosphate of soda (2NaO, HO, PO^{5}),
and one part of pure chloride of Ammonium (NH^{4}Cl.), in two parts of
boiling water, and allow it to cool. The greatest part of the formed
double salt crystallizes, while the mother-liquid contains chloride of
sodium, and some of the double salt. The crystals must be dissolved in
as little boiling water as possible, and re-crystallized. These
crystals must be dried and powdered.
When this double salt is heated, the water and the ammonia escape,
while the incombustible residue has a composition similar to borax,
viz., a free acid and an easily fusible salt. The effect of it is,
therefore, similar to the borax. The free phosphoric acid expels,
likewise, most other acids from their combinations, and combines with
metallic oxides.
For supports, the platinum wire may be used, but the hook must be
smaller than when borax is used, or the bead will not adhere. As for
all the other experiments with this salt, the microscosmic salt is
used the same as borax.
9. _Nitrate of Cobalt._--(CoO, NO^{5}).--This salt can be prepared by
dissolving pure oxide of cobalt in diluted nitric acid, and
evaporating to dryness with a low heat. The dry residue should be
dissolved in ten parts of water, and filtered. The filtrate is now
ready for use, and should be kept in a bottle with a glass stopper. If
the pure oxide of cobalt cannot be procured, then it may be prepared
by mixing two parts of finely powdered _glance of cobalt_ with four
parts of saltpetre, and one part of dry carbonate of potassa with one
part of water free from carbonate of soda. This mixture should be
added in successive portions into a red-hot Hessian crucible, and the
heat continued until the mass is fused, or at least greatly diminished
in volume. The cooled mass must be triturated with hot water, and then
heated with hydrochloric acid until it is dissolved and forms a dark
green solution, which generally presents a gelatinous appearance,
occasioned by separated silica. The solution is to be evaporated to
dryness, the dry residue moistened with hydrochloric acid, boiled with
water, filtered and neutralized while hot with carbonate of ammonia,
until it ceases to give an acid reaction with test-paper. This must
now be filtered again, and carbonate of potassa added to the filtrate
as long as a precipitate is produced. This precipitate is brought upon
a filter and washed thoroughly, and then dissolved in diluted nitric
acid. This is evaporated to dryness, and one part of it is dissolved
in ten parts of water for use.
The oxide of cobalt combines, with strong heat in the oxidation flame,
with various earths and infusible metallic oxides, and thus produces
peculiarly colored compounds, and is therefore used for their
detection; (alumina, magnesia, oxide of zinc, oxide of tin, etc.) Some
of the powdered substance is heated upon charcoal in the flame of
oxidation, and moistened with a drop of the solution of the nitrate of
cobalt, when the oxidation flame is thrown upon it. Alumina gives a
pure blue color, the oxide of zinc a bright green, magnesia a light
red, and the oxide of tin a bluish-green color; but the latter is only
distinctly visible after cooling.
The dropping bottle, is the most useful apparatus for the purpose of
getting small quantities of fluid. It is composed of a glass tube,
drawn out to a point, with a small orifice. This tube passes through
the cork of the bottle. By pressing in the cork into the neck of the
bottle, the air within will be compressed, and the liquid will rise in
the tube. If now we draw the cork out, with the tube filled with the
fluid, and pressing the finger upon the upper orifice, the fluid can
be forced out in the smallest quantity, even to a fraction of a drop.
10. _Tin._--This metal is used in the form of foil, cut into strips
about half an inch wide. Tin is very susceptible of oxidation, and
therefore deprives oxidized substances of their oxygen very quickly,
when heated in contact with them. It is employed in blowpipe analysis,
for the purpose of producing in glass beads a lower degree of
oxidation, particularly if the substance under examination contains
only a small portion of such oxide. These oxides give a characteristic
color to the bead, and thus are detected. The bead is heated upon
charcoal in the reduction flame, with a small portion of the tin,
whereby some of the tin is melted and mixes with the bead. The bead
should be reduced quickly in the reduction flame, for by continuing
the blast too great a while, the oxide of tin separates the other
oxides in the reduced or metallic state, while we only require that
they shall only be converted into a sub-oxide, in order that its
peculiar color may be recognized in the bead. The addition of too much
tin causes the bead to present an unclean appearance, and prevents
the required reaction.
11. _Silica_ (SiO^{3}).--This acid does not even expel carbonic acid
in the wet way, but in a glowing heat it expels the strongest volatile
acids. In blowpipe analysis, we use it fused with carbonate of soda to
a bead, as a test for sulphuric acid, and in some cases for phosphoric
acid. Also with carbonate of soda and borax, for the purpose of
separating tin from copper.
Finely powdered quartz will answer these purposes. If it cannot be
procured, take well washed white sand and mix it with two parts of
carbonate of soda and two parts of carbonate of potassa. Melt the
materials together, pound up the cooled mass, dissolve in hot water,
filter, add to the filtrate hydrochloric acid, and evaporate to
dryness. Moisten the dry residue with hydrochloric acid, and boil in
water. The silica remains insoluble. It should be washed well, dried,
and heated, and then reduced to powder.
12. TEST-PAPERS.--(_a._) _Blue, Litmus Paper._--Dissolve one part of
litmus in six or eight parts of water, and filter. Divide the filtrate
into two parts. In one of the parts neutralize the free alkali by
stirring it with a glass rod dipped in diluted sulphuric acid, until
the fluid appears slightly red. Then mix the two parts together, and
draw slips of unsized paper, free from alkali, such as fine filtering
paper. Hang these strips on a line to dry, in the shade and free from
floating dust. If the litmus solution is too light, it will not give
sufficient characteristic indications, and if too dark it is not
sensitive enough. The blue color of the paper should be changed to
red, when brought in contact with a solution containing the minutest
trace of free acid; but it should be recollected that the neutral
salts of the heavy metals produce the same change.
(_b._) _Red Litmus Paper._--The preparation of the red litmus paper is
similar to the above, the acid being added until a red color is
obtained. Reddened litmus paper is a very sensitive reagent for free
alkalies, the carbonates of the alkalies, alkaline earths, sulphides
of the alkalies and of the alkaline earths, and alkaline salts with
weak acids, such as boracic acid. These substances restore the
original blue color of the litmus.
(_c._) _Logwood Paper._--Take bruised logwood, boil it in water,
filter, and proceed as above. Logwood paper is a very delicate test
for free alkalies, which impart a violet tint to it. It is sometimes
used to detect hydrofluoric acid, which changes its color to yellow.
All the test-papers are to be cut into narrow strips, and preserved in
closely stopped vials. The especial employment of the test-papers we
shall allude to in another place.
B. ESPECIAL REAGENTS.
13. _Fused Boracic Acid_ (BO^{3}).--The commercial article is
sufficiently pure for blowpipe analysis. It is employed in some cases
to detect phosphoric acid, and also minute traces of copper in lead
compounds.
14. _Fluorspar_ (CaFl^{2}).--This substance should be pounded fine and
strongly heated. Fluorspar is often mixed with boracic acid, which
renders it unfit for analytical purposes. Such an admixture can be
detected if it be mixed with bisulphate of potassa, and exposed upon
platinum wire to the interior or blue flame. It is soon fused, the
boracic acid is reduced and evaporated, and by passing through the
external flame it is reoxidized, and colors the flame green. We use
fluorspar mixed with bisulphate of potassa as a test for lithia and
boracic acid in complicated compounds.
15. _Oxalate of Nickel_ (NiO, [=]O).--It is prepared by dissolving the
pure oxide of nickel in diluted hydrochloric acid. Evaporate to
dryness, dissolve in water, and precipitate with oxalate of ammonia.
The precipitate must be washed with caution upon a filter, and then
dried. It is employed in blowpipe analysis to detect salts of potassa
in the presence of sodium and lithium.
16. _Oxide of Copper_ (CuO).--Pure metallic copper is dissolved in
nitric acid. The solution is evaporated in a porcelain dish to
dryness, and gradually heated over a spirit-lamp, until the blue color
of the salt has disappeared and the mass presents a uniform black
color. The oxide of copper so prepared must be powdered, and preserved
in a vial. It serves to detect, in complicated compounds, minute
traces of chlorine.
17. _Antimoniate of Potassa_ (KO, SbO^{6}).--Mix four parts of the
bruised metal of antimony, with nine parts of saltpetre. Throw this
mixture, in small portions, into a red-hot Hessian crucible, and keep
it at a glowing heat for awhile after all the mixture is added. Boil
the cooled mass with water, and dry the residue. Take two parts of
this, and mix it with one part of dry carbonate of potassa, and expose
this to a red heat for about half an hour. Then wash the mass in cold
water, and boil the residue in water; filter, evaporate the filtrate
to dryness, and then, with a strong heat, render it free of water.
Powder it while it is warm, and preserve it in closed vials. It is
used for the detection of small quantities of charcoal in compound
substances, as it shares its oxygen with the carbonaceous matter, the
antimony becomes separated, and carbonate of potassa is produced,
which restores red litmus paper to blue, and effervesces with acids.
18. _Silver Foil._--A small piece of silver foil is used for the
purpose of detecting sulphur and the sulphides of the metals, which
impart a dark stain to it. If no silver foil is at hand, strips of
filtering paper, impregnated with acetate of lead, will answer in many
cases.
19. _Nitroprusside of Sodium_ (Fe^{2}Cy^{5}, NO^{5}, 2Na).--This is a
very delicate test for sulphur, and was discovered by Dr. Playfair.
This test has lately been examined with considerable ability by Prof.
J.W. Bailey, of West Point. If any sulphate or sulphide is heated by
the blowpipe upon charcoal with the carbonate of soda, and the fused
mass is placed on a watch-glass, with a little water, and a small
piece of the nitroprusside of sodium is added, there will be produced
a splendid purple color. This color, or reaction, will be produced
from any substance containing sulphur, such as the parings of the
nails, hair, albumen, etc. In regard to these latter substances, the
carbonate of soda should be mixed with a little starch, which will
prevent the loss of any of the sulphur by oxidation. Coil a piece of
hair around a platinum wire, moisten it, and dip it into a mixture of
carbonate of soda, to which a little starch has been added, and then
heat it with the blowpipe, when the fused mass will give with the
nitroprusside of sodium the characteristic purple reaction, indicative
of the presence of sulphur. With the proper delicacy of manipulation,
a piece of hair, half an inch in length, will give distinct
indications of sulphur.
_Preparation._--The nitroprussides of sodium and potassium (for either
salt will give the above reactions), are prepared as follows: One atom
(422 grains) of pulverized ferrocyanide of potassium is mixed with
five atoms of commercial nitric acid, diluted with an equal quantity
of water. One-fifth of this quantity (one atom) of the acid is
sufficient to transfer the ferrocyanide into nitroprusside; but the
use of a larger quantity is found to give the best results. The acid
is poured all at once upon the ferrocyanide, the cold produced by the
mixing being sufficient to moderate the action. The mixture first
assumes a milky appearance, but after a little while, the salt
dissolves, forming a coffee-colored solution, and gases are disengaged
in abundance. When the salt is completely dissolved, the solution is
found to contain ferrocyanide (red prussiate) of potassium, mixed with
nitroprusside and nitrate of the same base. It is then immediately
decanted into a large flask, and heated over the water-bath. It
continues to evolve gas, and after awhile, no longer yields a dark
blue precipitate with ferrous salts, but a dark green or slate-colored
precipitate. It is then removed from the fire, and left to
crystallize, whereupon it yields a large quantity of crystals of
nitre, and more or less oxamide. The strongly-colored mother liquid is
then neutralized with carbonate of potash or soda, according to the
salt to be prepared, and the solution is boiled, whereupon it
generally deposits a green or brown precipitate, which must be
separated by filtration. The liquid then contains nothing but
nitroprusside and nitrate of potash or soda. The nitrates being the
least soluble, are first crystallized, and the remaining liquid, on
farther evaporation, yields crystals of the nitroprusside. The sodium
salt crystallizes most easily.--(PLAYFAIR.)
As some substances, particularly in complicated compounds, are not
detected with sufficient nicety in the dry way of analysis, it will
often be necessary to resort to the wet way. It is therefore necessary
to have prepared the reagents required for such testing, as every
person, before he can become an expert blowpipe analyst, must be
acquainted with the characteristic tests as applied in the wet way.
* * * * *
Part II.
INITIATORY ANALYSIS.
Qualitative analysis refers to those examinations which relate simply
to the presence or the absence of certain substances, irrespective of
their quantities. But before we take cognizance of special
examinations, it would facilitate the progress of the student to pass
through a course of Initiatory Exercises. These at once lead into the
special analysis of all those substances susceptible of examination by
the blowpipe. The Initiatory Analysis is best studied by adopting the
following arrangement:
1. EXAMINATIONS WITH THE GLASS BULB.
The glass of which the bulb is made should be entirely free from lead,
otherwise fictitious results will ensue. If the bulb be of flint
glass, then by heating it, there is a slightly iridescent film caused
upon the surface of the glass, which may easily be mistaken for
arsenic. Besides, this kind of glass is easily fusible in the
oxidating flame of the blowpipe, while, in the reducing flame, its
ready decomposition would preclude its use entirely. The tube should
be composed of the potash or hard Bohemian glass, should be perfectly
white, and very thin, or the heat will crack it.
The tube should be perfectly clean, which can be easily attained by
wrapping a clean cotton rag around a small stick, and inserting it in
the tube. Before using the tube, see also that it is perfectly dry.
The quantity of the substance put into the tube for examination should
be small. From one to three grains is quite sufficient, as a general
rule, but circumstances vary the quantity. The sides of the tube
should not catch any of the substance as it is being placed at the
bottom of the tube, or into the bulb. If any of the powder, however,
should adhere, it should be pushed down with a roll of clean paper, or
the clean cotton rag referred to above.
In submitting the tube to the flame, it should be heated at first very
gently, the heat being increased until the glass begins to soften,
when the observations of what is ensuing within it may be made.
If the substance be of an organic nature, a peculiar empyreumatic odor
will be given off. If the substance chars, then it may be inferred
that it is of an organic nature. The matters which are given off and
cause the empyreumatic odor, are a peculiar oil, ammonia, carbonic
acid, acetic acid, water, cyanogen, and frequently other compounds. If
a piece of paper is heated in the bulb, a dark colored oil condenses
upon the sides of the tube, which has a strong empyreumatic odor. A
piece of litmus paper indicates that this oil is acid, as it is
quickly changed to red by contact with it. A black residue is now left
in the tube, and upon examination we will find that it is charcoal.
If, instead of the paper, a piece of animal substance is placed in
the bulb, the reddened litmus paper will be converted into its
original blue color, while charcoal will be left at the bottom of the
tube.
A changing of the substance, however, to a dark color, should not be
accepted as an invariable indication of charcoal, as some inorganic
bodies thus change color, but the dark substance will not be likely to
be mistaken for charcoal. By igniting the suspected substance with
nitrate of potassa, it can quickly be ascertained whether it is
organic or not, for if the latter, the vivid deflagration will
indicate it.
If the substance contains water, it will condense upon the cold
portion of the tube, and may be there examined as to whether it is
acid or alkaline. If the former, the matter under examination is,
perhaps, vegetable; if the latter, it is of an animal nature. The
water may be that fluid absorbed, or it may form a portion of its
constitution,
If the substance contain _sulphur_, the sublimate upon the cold part
of the tube may be recognized by its characteristic appearance,
especially if the substance should be a sulphide of tin, copper,
antimony, or iron. The hyposulphites, and several other sulphides,
also give off sulphur when heated. The volatile metals, mercury and
arsenic, will, however, sublime without undergoing decomposition. As
the sulphide of arsenic may be mistaken, from its color and
appearance, for sulphur, it must be examined especially for the
purpose of determining that point.
_Selenium_ will likewise sublime by heat as does sulphur. This is the
case if selenides are present. Selenium gives off the smell of decayed
horse-radish.
When the persalts are heated they are reduced to protosalts, with the
elimination of a part of their acid. This will be indicated by the
blue litmus paper.
If some of the neutral salts containing a volatile acid be present,
they will become decomposed. For instance, the red nitrous acid water
of the nitrates will indicate the decomposition of the salt,
especially if it be the nitrate of a metallic oxide.
If there is an odor of sulphur, then it is quite probable, if no free
sulphur be present, that a hyposulphite is decomposed.
If an oxalate be present, it is decomposed with the evolution of
carbonic oxide, which may be inflamed at the mouth of the tube; but
there are oxalates that give off carbonic acid gas, which, of course,
will not burn. A cyanide will become decomposed and eliminate nitrogen
gas, while the residue is charred. Some cyanides are, however, not
thus decomposed, as the dry cyanides of the earths and alkalies.
There are several oxides of metals which will sublime, and may be thus
examined in the tube. _Arsenious acid_ sublimes with great ease in
minute octohedral crystals. The oxides of tellurium and antimony will
sublime, the latter in minute glittering needles.
There are several metals which will sublime, and may be examined in
the cold portion of the tube. _Mercury_ condenses upon the tube in
minute globules. These often do not present the metallic appearance
until they are disturbed with a glass rod, when they attract each
other, and adhere as small globules. Place in the tube about a grain
of red precipitate of the drug stores and apply heat, when the oxide
will become decomposed, its oxygen will escape while the vaporized
mercury will condense upon the cold portion of the tube, and may there
be examined with a magnifying glass.
_Arsenic_, when vaporized, may be known by its peculiar alliaceous
odor. Arsenic is vaporized from its metallic state, and likewise from
its alloys. Several compounds which contain arsenic will also sublime,
such as the arsenical cobalt. Place in the bulb a small piece of
arsenical cobalt or "fly-stone," and apply heat. The sulphide of
arsenic will first rise, but soon the arsenic will adhere to the sides
of the tube.
The metals tellurium and cadmium are susceptible of solution, but the
heat required is a high one. This is best done upon charcoal.
The _perchloride of mercury_ sublimes undecomposed in the bulb,
previously undergoing fusion.
The _protochloride of mercury_ likewise sublimes, but it does not
undergo fusion first, as is the case with the corrosive sublimate.
The _ammoniacal salts_ all are susceptible of sublimation, which they
do without leaving a residue. There are, however, several which
contain fixed acids, which latter are left in the bulb. This is
particularly the case with the phosphates and borates. A piece of red
litmus paper will readily detect the escaping ammonia, while its odor
will indicate its presence with great certainty. The halogen compounds
of mercury, we should have mentioned, also sublime, the red iodide
giving a yellow sublimate.
The bulb is also a convenient little instrument for the purpose of
heating those substances which phosphoresce, and likewise those salts
that decrepitate.
Should the above reactions not be readily discerned, it should not be
considered as an indication that the substances are not present, for
they are frequently expelled in such combinations that the above
reactions will not take place. This is often the case with sulphur,
selenium, arsenic, and tellurium. It frequently happens, likewise,
that these substances are in such combinations that heat alone will
not sublime them; or else two or more of them may arise together, and
thus complicate the sublimate, so that the eye cannot readily detect
either substance. Sometimes sulphur and arsenic will coat the tube
with a metal-like appearance, which is deceptive. This coating
presents a metallic lustre at its lower portion, but changing, as it
progresses upward, to a dark brown, light brown, orange or yellow;
this sublimate being due to combinations of arsenic and sulphur, which
compounds are volatilized at a lower temperature than metallic
arsenic.
If certain reagents are mixed with many substances, changes are
effected which would not ensue with heat alone. _Formiate of soda_
possesses the property of readily reducing metallic oxides. When this
salt is heated, it gives off a quantity of carbonic oxide gas. This
gas, when in the presence of a metallic oxide, easily reduces the
metal, by withdrawing its oxygen from it, and being changed into
carbonic oxide. If a little fly-stone is mixed with some formiate of
soda, and heated in the bulb, the arsenic is reduced, volatilized, and
condenses in the cool portion of the tube. By this method, the
smallest portion of a grain of the arsenical compound may be thus
examined with the greatest readiness. If the residue is now washed, by
which the soda is got rid of, the metallic arsenic may be obtained in
small spangles. If the compound examined be the sulphide of antimony,
the one-thousandth part can be readily detected, and hence this method
is admirably adapted to the examination of medicinal antimonial
compounds. The arsenites of silver and copper are reduced by the
formiate of soda to their metals, mixed with metallic arsenic. The
mercurial salts are all reduced with the metal plainly visible as a
bright silvery ring on the cool portion of the tube. The chloride and
nitrate of silver are completely reduced, and may be obtained after
working out the soda, as bright metallic spangles. The salts of
antimony and zinc are thus reduced; also the sulphate of cadmium. The
sublimate of the latter, although in appearance not unlike that of
arsenic, can easily be distinguished by its brighter color. It is, in
fact, the rich yellow of this sublimate which has led artists to adopt
it as one of their most valued pigments.
2. EXAMINATIONS IN THE OPEN TUBE.
The substance to be operated upon should be placed in the tube, about
half an inch from the end, and the flame applied at first very
cautiously, increasing gradually to the required temperature. The
tube, in all these _roasting_ operations, as they are termed, should
be held in an inclined position. The nearer perpendicular the tube is
held, the stronger is the draught of air that passes through it. If
but little heat is required in the open tube operation, the
spirit-lamp is the best method of applying the heat. But if a greater
temperature is required, then recourse must be had to the blowpipe.
Upon the angle of inclination of the tube depends the amount of air
that passes through it, and therefore, the rapidity of the draught
may be easily regulated at the will of the operator. The inclination
of the tube may, as a general rule, be about the angle represented in
Fig. 14.
[Illustration Fig. 14.]
The length of the tube must be about six inches, so that the portion
upon which the substance rested in a previous examination may be cut
off. The portion of the tube left will answer for several similar
operations.
When the substance is under examination, we should devote our
attention to the nature of the sublimates, and to that of the _odors_
of the gases. If sulphur be in the substance experimented upon, the
characteristic odor of sulphurous acid gas will readily indicate the
sulphur. If metallic sulphides, for instance, are experimented upon,
the sulphurous acid gas eliminated will readily reveal their presence.
As it is a property of this gas to bleach, a piece of Brazil-wood test
paper should be held in the mouth of the tube, when its loss of color
will indicate the presence of the sulphurous acid. It often happens,
too, that a slight deposition of sulphur will be observed upon the
cool portion of the tube. This is particularly the case with those
sulphides, which yield sublimates of sulphur when heated in the bulb.
_Selenium_ undergoes but slight oxidation, but it becomes readily
volatilized, and may be observed on the cool portion of the tube. At
the same time the nose, if applied close to the end of the tube, will
detect the characteristic odor of rotten horse-radish. Arsenic also
gives its peculiar alliaceous odor, which is so characteristic that it
can be easily detected. A few of the arsenides produce this odor. The
_sublimates_ should be carefully observed, as they indicate often with
great certainty the presence of certain substances; for instance, that
of arsenic. The sublimate, in this case, presents itself as the
arsenious acid, or the metallic arsenic itself. If it be the former,
it may be discerned by aid of the magnifying glass as beautiful
glittering octohedral crystals. If the latter, the metallic lustre
will reveal it.
But it will be observed that while some of the arsenides are sublimed
at a comparatively low temperature, others require a very high one.
_Antimony_ gives a white sublimate when its salts are roasted, as the
sulphide, or the antimonides themselves, or the oxide of this metal.
This white sublimate is not antimonious acid, but there is mixed with
it the oxide of antimony with which the acid is sublimed. As is the
case with arsenious acid, the antimonious acid may, by dexterous
heating, be driven from one portion of the tube to another.
_Tellurium_, or its acid and oxide, may be got as a sublimate in the
tube. The tellurious acid, unlike the arsenious and antimonious acids,
cannot be driven from one portion of the tube to another, but, on the
contrary, it fuses into small clear globules, visible to the naked eye
sometimes, but quite so with the aid of the magnifying glass.
_Lead_, or its chloride, sublimes like tellurium, and, like that
substance, fuses into globules or drops.
_Bismuth_, or its sulphide, sublimes into an orange or brownish
globules, when it is melted, as directed above, for tellurium. The
color of the bismuth and lead oxides are somewhat similar, although
that of the latter is paler.
If any mineral containing _fluorine_, is fused, first with the
microcosmic salt bead, then put into the tube, and the flame of the
blowpipe be directed _into_ the tube upon the bead, hydrofluoric acid
is disengaged and attacks the inside of the tube. The fluoride of
calcium, or fluorspar, may be used for this experiment.
During the roasting, a brisk current of air should be allowed to pass
through the tube, whereby unoxidized matter may be prevented from
volatilization, and the clogging up of the substance under examination
be prevented.
3. EXAMINATIONS UPON CHARCOAL.
In making examinations upon charcoal, it is quite necessary that the
student should make himself familiar with the different and
characteristic appearances of the deposits upon the charcoal. In this
case I have found the advice given by Dr. Sherer to be the best; that
is, to begin with the examination of the pure materials first, until
the eye becomes familiarized with the appearances of their
incrustations upon charcoal.
The greater part of the metals fuse when submitted to the heat of the
blowpipe, and if exposed to the outer flame, they oxidize. These
metals, termed the noble metals, do not oxidize, but they fuse. The
metals platinum, iridium, rhodium, osmium and palladium do not fuse.
The metal osmium, if exposed to the flame of oxidation, fuses and is
finally dissipated as osmic acid. In the latter flame, the salts of
the noble metals are reduced to the metallic state, and the charcoal
is covered with the bright metal.
We shall give a brief description of the appearance of the principal
elementary bodies upon being fused with charcoal. This plan is that
deemed the most conducive to the progress of the student, by
Berzelius, Plattner, and Sherer. Experience has taught us that this
method is the most efficient that could have been devised as an
initiatory exercise for the student, ere he commences a more concise
and methodical method of analysis. In these reactions upon charcoal,
we shall follow nearly the language of Plattner and Sherer.
SELENIUM is not difficult of fusion, and gives off brown fumes in
either the oxidation or reduction flame. The deposit upon the charcoal
is of a steel-grey color, with a slightly metallic lustre. The deposit
however that fuses outside of this steel-grey one is of a dull violet
color, shading off to a light brown. Under the flame of oxidation this
deposit is easily driven from one portion of the charcoal to another,
while the application of the reducing flame volatilizes it with the
evolution of a beautiful blue light. The characteristic odor of
decayed horse-radish distinguishes the volatilization of this metal.
TELLURIUM.--This metal fuses with the greatest readiness, and is
reduced to vapor under both flames with fumes, and coats the charcoal
with a deposit of tellurous acid. This deposit is white near the
centre, and is of a dark yellow near the edges. It may be driven from
place to place by the flame of oxidation, while that of reduction
volatilizes it with a green flame. If there be a mixture of selenium
present, then the color of the flame is bluish-green.
ARSENIC.--This metal is volatilized without fusing, and covers the
charcoal both in the oxidizing and reducing flames with a deposit of
arsenious acid. This coating is white in the centre, and grey towards
the edges, and is found some distance from the assay. By the most
gentle application of the flame, it is immediately volatilized, and if
touched for a moment with the reducing flame, it disappears, tinging
the flame pale blue. During volatilization a strong garlic odor is
distinctly perceptible, very characteristic of arsenic, and by which
its presence in any compound may be immediately recognized.
ANTIMONY.--This metal fuses readily, and coats the charcoal under both
flames with antimonious acid. This incrustation is of a white color
where thick, but of a bluish tint where it is thin, and is found
nearer to the assay than that of arsenic. When greatly heated by the
flame of oxidation, it is driven from place to place without coloring
the flame, but when volatilized by the flame of reduction, it tinges
the flame blue. As antimonious acid is not so volatile as arsenious
acid, they may thus be easily distinguished from one another.
When metallic antimony is fused upon charcoal, and the metallic bead
raised to a red heat, if the blast be suspended, the fluid bead
remains for some time at this temperature, giving off opaque white
fumes, which are at first deposited on the surrounding charcoal, and
then upon the bead itself, covering it with white, pearly crystals.
The phenomenon is dependent upon the fact, that the heated button of
antimony, in absorbing oxygen from the air, developes sufficient heat
to maintain the metal in a fluid state, until it becomes entirely
covered with crystals of antimonious acid so formed.
BISMUTH.--This metal fuses with ease, and under both flames covers the
charcoal with a coating of oxide, which, while hot, is of an
orange-yellow color, and after cooling, of a lemon-yellow color,
passing, at the edges, into a bluish white. This white coating
consists of the carbonate of bismuth. The sublimate from bismuth is
formed at a less distance from the assay than is the case with
antimony. It may be driven from place to place by the application of
either flame; but in so doing, the oxide is first reduced by the
heated charcoal, and the metallic bismuth so formed is volatilized and
reoxidized. The flame is uncolored.
LEAD.--This metal readily fuses under either flame, and incrusts the
charcoal with oxide at about the same distance from the assay as is
the case with bismuth. The oxide is, while hot, of a dark lemon-yellow
color, but upon cooling, becomes of a sulphur yellow. The carbonate
which is formed upon the charcoal, beyond the oxide, is of a
bluish-white color. If the yellow incrustation of the oxide be heated
with the flame of oxidation, it disappears, undergoing changes similar
to those of bismuth above mentioned. Under the flame of reduction,
it, however, disappears, tinging the flame blue.
CADMIUM.--This metal fuses with ease, and, in the flame of oxidation,
takes fire, and burns with a deep yellow color, giving off brown
fumes, which coat the charcoal, to within a small distance of the
assay, with oxide of cadmium. This coating exhibits its characteristic
reddish-brown color most clearly when cold. Where the coating is very
thin, it passes to an orange color. As oxide of cadmium is easily
reduced, and the metal very volatile, the coating of oxide may be
driven from place to place by the application of either flame, to
neither of which does it impart any color. Around the deposit of
oxide, the charcoal has occasionally a variegated tarnish.
ZINC.--This metal fuses with ease, and takes fire in the flame of
oxidation, burning with a brilliant greenish-white light, and forming
thick white fumes of oxide of zinc, which coat the charcoal round the
assay. This coating is yellow while hot, but when perfectly cooled,
becomes white. If heated with the flame of oxidation, it shines
brilliantly, but is not volatilized, since the heated charcoal is,
under these circumstances, insufficient to effect its reduction. Even
under the reducing flame, it disappears very slowly.
TIN.--This metal fuses readily, and, in the flame of oxidation,
becomes covered with oxide, which, by a strong blast, may be easily
blown off. In the reducing flame, the fused metal assumes a white
surface, and the charcoal becomes covered with oxide. This oxide is of
a pale yellow color while hot, and is quite brilliant when the flame
of oxidation is directed upon it. After cooling, it becomes white. It
is found immediately around the assay, and cannot be volatilized by
the application of either flame.
MOLYBDENUM.--This metal, in powder, is infusible before the blowpipe.
If heated in the outer flame, it becomes gradually oxidized, and
incrusts the charcoal, at a small distance from the assay, with
molybdic acid, which, near the assay, forms transparent crystalline
scales, and is elsewhere deposited as a fine powder. The incrustation,
while hot, is of a yellow color, but becomes white after cooling. It
may be volatilized by heating with either flame, and leaves the
surface of the charcoal, when perfectly cooled, of a dark-red copper
color, with a metallic lustre, due to the oxide of molybdenum, which
has been formed by the reducing action of the charcoal upon the
molybdic acid. In the reducing flame, metallic molybdenum remains
unchanged.
SILVER.--This metal, when fused alone, and kept in this state for some
time, under a strong oxidizing flame, covers the charcoal with a thin
film of dark reddish-brown oxide. If the silver be alloyed with lead,
a yellow incrustation of the oxide of that metal is first formed, and
afterwards, as the silver becomes more pure, a dark red deposit is
formed on the charcoal beyond. If the silver contains a small quantity
of antimony, a white incrustation of antimonious acid is formed, which
becomes red on the surface if the blast be continued. And if lead and
antimony are both present in the silver, after the greater part of
these metals have been volatilized, a beautiful crimson incrustation
is produced upon the charcoal. This result is sometimes obtained in
fusing rich silver ores on charcoal.
SULPHIDES, CHLORIDES, IODIDES, AND BROMIDES.
In blowpipe experiments, it rarely occurs that we have to deal with
pure metals, which, if not absolutely non-volatile, are recognized by
the incrustation they form upon charcoal. Some compound substances,
when heated upon charcoal, form white incrustations, resembling that
formed by antimony, and which, when heated, may, in like manner, be
driven from place to place. Among these are certain sulphides, as
sulphide of potassium, and sulphide of sodium, which are formed by the
action of the reducing flame upon the sulphates of potassa and soda,
and are, when volatilized, reconverted into those sulphates, and as
such deposited on the charcoal. No incrustation is, however, formed,
until the whole of the alkaline sulphate has been absorbed into the
charcoal, and has parted with its oxygen. As sulphide of potassium is
more volatile than sulphide of sodium, an incrustation is formed from
the former sooner than from the latter of these salts, and is
considerably thicker in the former case. If the potash incrustation be
touched with the reducing flame, it disappears with a violet-colored
flame; and if a soda incrustation be treated in like manner, an
orange-yellow flame is produced.
Sulphide of lithium, formed by heating the sulphate in the reducing
flame, is volatilized in similar manner by a strong blast, although
less readily than the sulphide of sodium. It affords a greyish white
film, which disappears with a crimson flame when submitted to the
reducing flame.
Besides the above, the sulphides of bismuth and lead give, when heated
in either flame, two different incrustations, of which the more
volatile is of a white color, and consists in the one case of sulphate
of lead, and in the other of sulphate of bismuth. If either of these
be heated under the reducing flame, it disappears in the former case
with a bluish flame, in the latter unaccompanied by any visible flame.
The incrustation formed nearest to the assay consists of the oxide of
lead or bismuth, and is easily recognized by its color when hot and
after cooling. There are many other metallic sulphides, which, when
heated by the blowpipe flame, cover the charcoal with a white
incrustation, as sulphide of antimony, sulphide of zinc, and sulphide
of tin. In all these cases, however, the incrustation consists of the
metallic oxide alone, and either volatilizes or remains unchanged,
when submitted to the oxidizing flame.
Of the metallic chlorides there are many which, when heated on
charcoal with the blowpipe flame, are volatilized and redeposited as a
white incrustation. Among these are the chlorides of potassium,
sodium, and lithium, which volatilize and cover the charcoal
immediately around the assay with a thin white film, after they have
been fused and absorbed into the charcoal, chloride of potassium forms
the thickest deposit, and chloride of lithium the thinnest, the
latter being moreover of a greyish-white color. The chlorides of
ammonium, mercury, and antimony volatilize without fusing.
The chlorides of zinc, cadmium, lead, bismuth, and tin first fuse and
then cover the charcoal with two different incrustations, one of which
is a white volatile chloride, and the other a less volatile oxide of
the metal.
Some of the incrustations formed by metallic chlorides disappear with
a colored flame when heated with the reducing flame; thus chloride of
potassium affords a violet flame, chloride of sodium an orange one,
chloride of lithium a crimson flame, and chloride of lead a blue one.
The other metals mentioned above volatilize without coloring the
flame.
The chloride of copper fuses and colors the flame of a beautiful blue.
Moreover, if a continuous blast be directed upon the salt, a part of
it is driven off in the form of white fumes which smell strongly of
chlorine, and the charcoal is covered with incrustations of three
different colors. That which is formed nearest to the assay is of a
dark grey color, the next, a dark yellow passing into brown, and the
most distant of a bluish white color. If this incrustation be heated
under the reducing flame, it disappears with a blue flame.
Metallic iodides and bromides behave upon charcoal in a similar manner
to the chlorides. Those principally deserving of mention are the
bromides and iodides of potassium and sodium. These fuse upon
charcoal, are absorbed into its pores, and volatilize in the form of
white fumes, which are deposited upon the charcoal at some distance
from the assay. When the saline films so formed are submitted to the
reducing flame, they disappear, coloring the flame in the same manner
as the corresponding chlorides.
4. EXAMINATIONS IN THE PLATINUM FORCEPS.
Before the student attempts to make an examination in the platinum
forceps or tongs, he should first ascertain whether or not it will
act upon the platinum. If the substance to be examined shall act
chemically upon the platinum, then it should be examined on the
charcoal, and the color of the flame ascertained as rigidly as
possible. The following list of substances produce the color attached
to them.
A. VIOLET.
Potash, and all its compounds, with the exception of the phosphate
and the borate, tinge the color of the flame violet.
B. BLUE.
Chloride of copper, Intense blue.
Lead, Pale clear blue.
Bromide of copper, Bluish green.
Antimony, Bluish green.
Selenium, Blue.
Arsenic, English green.
C. GREEN.
Ammonia, Dark green.
Boracic acid, Dark green.
Copper, Dark green.
Tellurium, Dark green.
Zinc, Light green.
Baryta Apple green.
Phosphoric acid, Pale green.
Molybdic acid, Apple green.
Telluric acid, Light green.
D. YELLOW.
Soda, Intense yellow.
Water, Feeble yellow.
E. RED.
Strontia, Intense crimson.
Lithia, Purplish red.
Potash, Violet red.
Lime, Purplish red.
The student may often be deceived in regard to the colors: for
instance, if a small splinter of almost any mineral be held at the
point of the flame of oxidation, it will impart a very slight yellow
to the flame. This is caused, doubtless, by the water contained in the
mineral. If the piece of platinum wire is used, and it should be wet
with the saliva, as is frequently done by the student, then the small
quantity of soda existing in that fluid will color the flame of a
light yellow hue.
A. THE VIOLET COLOR.
The salts of potash, with the exception of the borate and the
phosphate, color the flame of a rich violet hue. This color is best
discovered in the outer flame of the blowpipe, as is the case with all
the other colors. The flame should be a small one, with a lamp having
a small wick, while the orifice of the blowpipe must be quite small.
These experiments should likewise be made in a dark room, so that the
colors may be discerned with the greatest ease. In investigating with
potash for the discernment of color, it should be borne in mind that
the least quantity of soda will entirely destroy the violet color of
the potash, by the substitution of its own strong yellow color. If
there be not more than the two hundredth part of soda, the violet
reaction of the potash will be destroyed. This is likewise the case
with the presence of lithia, for its peculiar red color will destroy
the violet of the potash. Therefore in making investigations with the
silicates which contain potash, the violet color of the latter can
only be discerned when they are free from soda and lithia.
B. THE BLUE COLOR.
(_a._) _The Chloride of Copper._--Any of the chlorides produce a blue
color in the blowpipe flame, or any salt which contains chlorine will
show the blue tint, as the color in this case is referable to the
chlorine itself. There are, however, some chlorides which, in
consequence of the peculiar reactions of their bases, will not produce
the blue color, although in these cases the blue of the chlorine will
be very likely to blend itself with the color produced by the base.
The chloride of copper communicates an intense blue to the flame, when
fused on the platinum wire. If the heat be continued until the
chlorine is driven off, then the greenish hue of the oxide of copper
will be discerned.
(_b._) _Lead._--Metallic lead communicates to the flame a pale blue
color. The oxide reacts in the same manner. The lead-salts, whose
acids do not interfere with the color, impart also a fine blue to the
flame, either in the platina forceps, or the crooked wire.
(_c._) _Bromide of Copper._--This salt colors the flame of a
bluish-green color, but when the bromine is driven off, then we have
the green of the oxide of copper.
(_d._) _Antimony._--This metal imparts a blue color to the blowpipe
flame, but if the metal is in too small a quantity, then the color is
a brilliant white. If antimony is fused on charcoal, the fused metal
gives a blue color. The white sublimate which surrounds the fused
metal, being subjected to the flame of oxidation, disappears from the
charcoal with a bluish-green color.
(_e._) _Selenium._--If fused in the flame of oxidation, it imparts to
the flame a deep blue color. The incrustation upon charcoal gives to
the flame the same rich color.
(_f._) _Arsenic._--The arseniates and metallic arsenic itself impart
to the blowpipe flame a fine blue color, provided that there is no
other body present which may have a tendency to color the flame with
its characteristic hue. The sublimate of arsenious acid which
surrounds the assay, will give the same blue flame, when dissipated by
the oxidation flame. The platinum forceps will answer for the
exhibition of the color of arsenic, even though the salts be
arseniates, whose bases possess the property of imparting their
peculiar color to the flame, such as the arseniate of lime.
C. THE GREEN COLOR.
(_a._) _Ammonia._--The salts of ammonia, when heated before the
blowpipe, and just upon the point of disappearing, impart to the flame
a feeble though dark green color. This color, however, can only be
discerned in a dark room.
(_b._) _Boracic Acid._--If any one of the borates is mixed with two
parts of a flux composed of one part of pulverized fluorspar, and four
and a half parts of bisulphate of potash, and after being melted, is
put upon the coil of a platinum wire, and held at the point of the
blue flame, soon after fusion takes place a dark green color is
discerned, but it is not of long duration. The above process is that
recommended by Dr. Turner. The green color of the borates may be
readily seen by dipping them, previously moistened with sulphuric
acid, into the upper part of the blue flame, when the color can be
readily discerned. If soda be present, then the rich green of the
boracic acid is marred by the yellow of the soda. Borax, or the
biborate of soda (NaO, 2BO_{3}) may be used for this latter reaction,
but if it be moistened with sulphuric acid, the green of the boracic
acid can then be seen. If the borates, or minerals which contain
boracic acid, are fused on charcoal with carbonate of potash, then
moistened with sulphuric acid and alcohol, then the bright green of
the boracic acid is produced, even if the mineral contains but a
minute portion of the boracic acid.
(_c._) _Copper_. Nearly all the ores of copper and its salts, give a
bright green color to the blowpipe flame. Metallic copper likewise
colors the flame green, being first oxidized. If iodine, chlorine, and
bromine are present, the flame is considerably modified, but the
former at least intensifies the color. Many ores containing copper
also color the flame green, but the internal portion is of a bright
blue color if the compound contains lead, the latter color being due
to the lead. The native sulphide and carbonate of copper should be
moistened with sulphuric acid, while the former should be previously
roasted. If hydrochloric acid is used for moistening the salts, then
the rich green given by that moistened with the sulphuric acid is
changed to a blue, being thus modified by the chlorine of the acid.
Silicates containing copper, if heated in the flame in the platinum
forceps, impart a rich green color to the outer flame. In fact, if any
substance containing copper be submitted to the blowpipe flame, it
will tinge it green, provided there be no other substance present to
impart its own color to the flame, and thus modify or mar that of the
copper.
(_d._) _Tellurium._--If the flame of reduction is directed upon the
oxide of tellurium placed upon charcoal, a green color is imparted to
it. If the telluric acid be placed upon platinum wire in the reduction
flame, the oxidation flame is colored green. Or if the sublimate be
dissipated by the flame of oxidation, it gives a green color. If
selenium be present, the green color is changed to a blue.
(_e._) _Zinc._--The oxide of zinc, when strongly heated, gives a blue
flame. This is especially the case in the reducing flame. The flame is
a small one, however, and not very characteristic, as with certain
preparations of zinc the blue color is changed to a bright white. The
soluble salts of zinc give no blue color.
(_f._) _Baryta._--The soluble salts of baryta, moistened, and then
submitted to the reduction flame, produce a green color. The salt
should be moistened, when the color will be strongly marked in the
outer flame. The insoluble salts do not produce so vivid a color as
the soluble salts, and they are brighter when they have previously
been moistened. The carbonate does not give a strong color, but the
acetate does, so long as it is not allowed to turn to a carbonate. The
chloride, when fused on the platinum wire, in the point of the
reduction flame, imparts a fine green color to the oxidation flame.
This tint changes finally to a faint dirty green color. The sulphate
of baryta colors the flame green when heated at the point of the
reduction flame. But neither the sulphate, carbonate, nor, in fact,
any other salt of baryta, gives such a fine green color as the
chloride. The presence of lime does interfere with the reaction of
baryta, but still does not destroy its color.
(_g._) _Phosphoric Acid._--The phosphates give a green color to the
oxidation flame, especially when they are moistened with sulphuric
acid. This is best shown with the platinum forceps. The green of
phosphoric, or the phosphates, is much less intense than that of the
borates or boracic acid, but yet the reaction is a certain one, and is
susceptible of considerable delicacy, either with the forceps, or
still better upon platinum wire. Sulphuric acid is a great aid to the
development of the color, especially if other salts be present which
would be liable to hide the color of the phosphoric acid. In this
reaction with phosphates, the water should be expelled from them
previous to melting them with sulphuric acid. They should likewise be
pulverized. Should soda be present it will only exhibit its peculiar
color after the phosphoric acid shall have been expelled; therefore,
the green color of the phosphoric acid should be looked for
immediately upon submitting the phosphate to heat.
(_h._) _Molybdic Acid._--If this acid or the oxide of molybdenum be
exposed upon a platinum wire to the point of the reduction flame, a
bright green color is communicated to the flame of oxidation. Take a
small piece of the native sulphide of molybdenum, and expose it in the
platinum tongs to the flame referred to above, when the green color
characteristic of this metal will be exhibited.
(_i._) _Telluric Acid._--If the flame of reduction is directed upon a
small piece of the oxide of tellurium placed upon charcoal, a bright
green color is produced. Or if telluric acid be submitted to the
reduction flame upon the loop of a platinum wire, it communicates to
the outer flame the bright green of tellurium. If the sublimate found
upon the charcoal in the first experiment be submitted to the blowpipe
flame, the green color of tellurium is produced while the sublimate is
volatilized. If selenium be present the green color is changed to a
deep blue one.
D. YELLOW.
The salts of soda all give a bright yellow color when heated in the
platinum loop in the reduction flame. This color is very persistent,
and will destroy the color of almost any other substance. Every
mineral of which soda is a constituent, give this bright orange-yellow
reaction. Even the silicate of soda itself imparts to the flame of
oxidation the characteristic yellow of soda.
E. RED.
(_a._) _Strontia._--Moisten a small piece of the chloride of
strontium, put it in the platinum forceps and submit it to the flame
of reduction, when the outer flame will become colored of an intense
red. If the salt of strontia should be a soluble one, the reaction is
of a deeper color than if an insoluble salt is used, while the color
is of a deeper crimson if the salt is moistened. If the salt be a
soluble one, it should be moistened and dipped into the flame, while
if it be an insoluble salt, it should be kept dry and exposed beyond
the point of the flame. The carbonate of strontia should be moistened
with hydrochloric acid instead of water, by which its color similates
that of the chloride of strontium when moistened with water. In
consequence of the decided red color which strontia communicates to
flame, it is used by pyrotechnists for the purpose of making their
"crimson fire."
(_b._) _Lithia._--The color of the flame of lithia is slightly
inclined to purple. The chloride, when placed in the platinum loop,
gives to the outer flame a bright red color, sometimes with a slight
tinge of purple. Potash does not prevent this reaction, although it
may modify it to violet; but the decided color of soda changes the red
of lithia to an orange color. If much soda be present, the color of
the lithia is lost entirely. The color of the chloride of lithium may
be distinctly produced before the point of the blue flame, and its
durability may be the means of determining it from that of lithium,
as the latter, under the same conditions, is quite evanescent. The
minerals which contain lithia, frequently contain soda, and thus the
latter destroys the color of the former.
(_c._) _Potash._--The salts of potash, if the acid does not interfere,
give a purplish-red color before the blowpipe; but as the color is
more discernibly a purple, we have classed it under that color.
(_d._) _Lime._--The color of the flame of lime does not greatly differ
from that of strontia, with the exception that it is not so decided.
Arragonite and calcareous spar, moistened with hydrochloric acid, and
tried as directed for strontia, produce a red light, not unlike that
of strontia. The chloride of calcium gives a red tinge, but not nearly
so decided as the chloride of strontium. The carbonate of lime will
produce a yellowish flame for a while, until the carbonic acid is
driven off, when the red color of the lime may be discerned.
If the borate or phosphate of lime be used, the green color of the
acids predominates over the red of the lime. Baryta also destroys the
red color of the lime, by mixing its green color with it. There is but
one silicate of lime which colors the flame red, it is the variety
termed tabular spar.
5. EXAMINATIONS IN THE BORAX BEAD.
In order to examine a substance in borax, the loop of the platinum
wire should, after being thoroughly cleaned, and heated to redness, be
quickly dipped into the powdered borax, and then quickly transferred
to the flame of oxidation, and there fused. If the bead is not large
enough to fill the loop of the wire, it must be subjected again to the
same process. By examining the bead, both when hot and cold, by
holding it up against the light, it can be soon ascertained whether it
is free from dirt by the transparency, or the want of it, of the bead.
In order to make the examination of a substance, the bead should be
melted and pressed against it, when enough will adhere to answer the
purpose. This powder should then be fused in the oxidation flame until
it mixes with, and is thoroughly dissolved by the borax bead.
The principal objects to be determined now are: the color of the borax
bead, both when heated and when cooled; also the rapidity with which
the substance dissolves in the bead, and if any gas is eliminated.
If the color of the bead is the object desired, the quantity of the
substance employed must be very small, else the bead will be so deeply
colored, as in some cases to appear almost opaque, as, for instance,
in that of cobalt. Should this be the case, then, while the bead is
still red hot, it should be pressed flat with the forceps; or it may,
while soft, be pulled out to a thin thread, whereby the color can be
distinctly discovered.
Some bodies, when heated in the borax bead, present a clear bead both
while hot and cold; but if the bead be heated with the intermittent
flame, or in the flame of reduction, it becomes opalescent, opaque or
milk-white. The alkaline earths are instances of this kind of
reaction, also glucina oxide of cerium, tantalic and titanic acids,
yttria and zirconia. But if a small portion of silica should be
present, then the bead becomes clear. This is likewise the case with
some silicates, provided there be not too large a quantity present,
that is: over the quantity necessary to saturate the borax, for, in
that case, the bead will be opaque when cool.
If the bead be heated on charcoal, a small tube or cavity must be
scooped out of the charcoal, the bead placed in it, and the flame of
reduction played upon it. When the bead is perfectly fused, it is
taken up between the platinum forceps and pressed flat, so that the
color may be the more readily discerned. This quick cooling also
prevents the protoxides, if there be any present, from passing into a
higher degree of oxidation.
The bead should first be submitted to the oxidation flame, and any
reaction carefully observed. Then the bead should be submitted to the
flame of reduction. It must be observed that the platinum forceps
should not be used when there is danger of a metallic oxide being
reduced, as in this case the metal would alloy with the platinum and
spoil the forceps. In this case charcoal should be used for the
support. If, however, there be oxides present which are not reduced by
the borax, then the platinum loop may be used. Tin is frequently used
for the purpose of enabling the bead to acquire a color for an oxide
in the reducing flame, by its affinity for oxygen. The oxide, thus
being reduced to a lower degree of oxidation, imparts its peculiar
tinge to the bead as it cools.
The arsenides and sulphides, before being examined, should be roasted,
and then heated with the borax bead. The arsenic of the former, it
should be observed, will act on the glass tube in which the
sublimation is proceeding, if the glass should contain lead.
It should be recollected that earths, metallic oxides, and metallic
acids are soluble in borax, except those of the easily reducible
metals, such as platinum or gold, or of mercury, which too readily
vaporize. Also the metallic sulphides, after the sulphur has been
driven off. Also the salts of metals, after their acids are driven off
by heat. Also the nitrates and carbonates, after their acids are
driven off during the fusion. Also the salts of the halogens, such as
the chlorides, iodides, bromides, etc., of the metals. Also the
silicates, but with great tardiness. Also the phosphates and borates
that fuse in the bead without suffering decomposition. The metallic
sulphides are insoluble in borax, and many of the metals in the pure
state.
There are many substances which give clear beads with borax both while
hot and cold, but which, upon being heated with the intermittent
oxidation flame, become enamelled and opaque. The intermittent flame
may be readily attained, not by varying the force of the air from the
mouth, but by raising and depressing the bead before the point of the
steady oxidating flame. The addition of a little nitrate of potash
will often greatly facilitate the production of a color, as it
oxidizes the metal. The hot bead should be pressed upon a small
crystal of the nitrate, when the bead swells, intumesces, and the
color is manifested in the surface of the bead,
6. EXAMINATIONS IN MICROCOSMIC SALT.
Microcosmic salt is a better flux for many metallic oxides than borax,
as the colors are exhibited in it with more strength and character.
Microcosmic salt is the phosphate of soda and ammonia. When it is
ignited it passes into the biphosphate of soda, the ammonia being
driven off. This biphosphate of soda possesses an excess of phosphoric
acid, and thus has the property of dissolving a great number of
substances, in fact almost any one, with the exception of silica. If
the substances treated with this salt consist of sulphides or
arsenides, the bead must be heated on charcoal. But if the substance
experimented upon consists of earthly ingredients or metallic oxides,
the platinum wire is the best. If the latter is used a few additional
turns should be given to the wire in consequence of the greater
fluidity of the bead over that of borax. The microcosmic salt bead
possesses the advantage over that of borax, that the colors of many
substances are better discerned in it, and that it separates the
acids, the more volatile ones being dissipated, while the fixed ones
combine with a portion of the base equally with the phosphoric acid,
or else do not combine at all, but float about in the bead, as is the
case particularly with silicic acid. Many of the silicates give with
borax a clear bead, while they form with microcosmic salt an
opalescent one.
It frequently happens, that if a metallic oxide will not give its
peculiar color in one of the flames, that it will in the other, as the
difference in degree with which the metal is oxidized often determines
the color. If the bead is heated in the reducing flame, it is well
that it should be cooled rapidly to prevent a reoxidation. Reduction
is much facilitated by the employment of metallic tin, whereby the
protoxide or the reduced metal may be obtained in a comparatively
brief time.
The following tables, taken from Plattner and Sherer, will present the
reactions of the metallic oxides, and some of the metallic acids, in
such a clear light, that the student cannot very easily be led astray,
if he gives the least attention to them. It frequently happens that a
tabular statement of reactions will impress facts upon the memory when
long detailed descriptions will fail to do so. It is for this purpose
that we subjoin the following excellent tables.
* * * * *
TABLE I.
A. BORAX.
1. Oxydizing flame.
2. Reducing "
B. MICROCOSMIC SALT.
1. Oxydizing flame.
2. Reducing "
A. BORAX
1. Oxydizing flame
--------------------------------------------------------------------------
Color of Bead.
--+-----------------------------------------------------------------------
| Substances which produce this color
+--------------------------------------+--------------------------------
| in the hot bead. | in the cold bead.
--+--------------------------------------+--------------------------------
Colorless
-----------------------------------------+--------------------------------
| Silica \ | Silica
| Alumina \ | Alumina _
| Oxide of Tin | | Oxide of Tin \
| Telluric Acid | | Telluric Acid \
| Baryta | | Baryta \
| Strontia | | Strontia |
| Lime | | Lime |
| Magnesia | | Magnesia |
| Glucina | In all | Glucina |
| Yttria } proportions. | Yttria |
| Zirconia | | Zirconia |
| Thoria | | Thoria |With
| Oxide of Lanthanum | | Oxide of Lanthanum |intermittent
| | | " " Silver }flame
| Tantalic Acid | | Tantalic Acid |opaque
| Niobic " | | Niobic " |white.
| Pelopic " / | Pelopic " |
| Titanic " _/ | Titanic " |
| _ | |
| Tungstic " \ In small | Tungstic " |
| Molybdic " \ quantity | Molybdic " |
| Oxide of Zinc | only. | Oxide of Zinc /
| " " Cadmium } | " " Cadmium_/
| " " Lead | In large | " " Lead
| " " Bismuth / quantity | " " Bismuth
| " " Antimony / yellow. | " " Antimony
--+-----------+--------------------------+--------------------------------
Yellow, orange-red and reddish-brown.
--+-----------+--------------------------+--------------------------------
| _ |
| Titanic Acid, yellow \ |
| Tungstic Acid, yellow \ |
| Molybdic Acid, dark yellow|when in |
| Oxide of Zinc, pale-yellow|large |
| Oxide of Cadmium, }quantity. |
| pale-yellow |Otherwise |
| Oxide of Lead, yellow |colorless.|
| Oxide of Bismuth, orange / |
| Oxide of Antimony, yellow/ |
| Oxide of Cerium, red | Oxide of Cerium with interm.
| Oxide of Iron, dark red | flame opaque white.
| Oxide of Uranium, red | Oxide of Iron, yellow
| Oxide of Silver | Oxide of Uranium with interm.
| | flame opaque yellow.
| | Oxide of Silver in large
| | proportion, with interm.
| | flame yellow.
| Vanadic Acid, yellow | Vanadic Acid, yellow.
| Oxide of Chromium, dark-red | Oxide of Nickel,
| | reddish-brown.
| | Oxide of Manganese, red to
| | violet.
--+--------------------------------------+--------------------------------
Violet or Amethyst.
--+--------------------------------------+--------------------------------
| Oxide of Nickel |
| " " Manganese | Oxide of Didymium.
| " " Didymium |
--+--------------------------------------+--------------------------------
Blue.
--+--------------------------------------+--------------------------------
| Oxide of Cobalt | Oxide of Cobalt.
| | " Copper, blue to
| | greenish-blue.
--+--------------------------------------+--------------------------------
Green.
--+--------------------------------------+--------------------------------
| Oxide of Copper | Oxide of Chromium, with
| | yellowish tinge.
--+--------------------------------------+--------------------------------
A. BORAX
2. Reducing flame
--+--------------------------------------+--------------------------------
Color of Bead.
--+-----------------------------------------------------------------------
| Substances which produce this color
+--------------------------------------+--------------------------------
| in the hot bead. | in the cold bead.
--+--------------------------------------+--------------------------------
Colorless
--+--------------------------------------+--------------------------------
| Silica | Silica
| Alumina | Alumina
| Oxide of Tin | Oxide of Tin _
| Baryta | Baryta \
| Strontia | Strontia \
| Lime | Lime |
| Magnesia | Magnesia |With
| Glucina | Glucina |intermittent
| Yttria | Yttria }flame
| Zirconia | Zirconia |opaque-white.
| Thoria | Thoria only when |
| | saturated |
| Oxide of Lanthanum | Oxide of Lanthanum |
| " " Cerium | " " Cerium /
| Tantalic Acid | Tantalic Acid _/
| Oxide of Didymium | Oxide of Didymium
| " " Manganese | " " Manganese
| _ | _
| Niobic Acid \ In small | Niobic Acid \ In small
| Pelopic " } proportions. | Pelopic " } proportions.
| _/ | _/
| _ | _
| Oxide of Silver \ | Oxide of Silver \ After
| " " Zinc \ After long | " " Zinc \ long
| " " Cadmium | continued | " " Cadmium | continued
| " " Lead } blowing. | " " Lead } blowing.
| " " Bismuth | Otherwise | " " Bismuth | Otherwise
| " " Antimony| grey. | " " Antimony | grey.
| " " Nickel / | " " Nickel /
| Telluric Acid _/ | Telluric Acid _/
--+--------------------------------------+--------------------------------
Yellow to brown.
--+--------------------------------------+--------------------------------
| Titanic Acid | Titanic Acid.
| Tungstic " | Tungstic "
| Molybdic " | Molybdic "
| Vanadic " |
--+--------------------------------------+--------------------------------
Blue.
--+--------------------------------------+--------------------------------
| Oxide of Cobalt. | Oxide of Cobalt.
| | Titanic Acid with intermittent
| | flame opaque-blue.
--+--------------------------------------+--------------------------------
Green.
--+--------------------------------------+--------------------------------
| Oxide of Iron | Oxide of Iron, bottle-green.
| " " Uranium | Oxide of Uranium, bottle-
| " " Chromium | green.
| | Oxide of Chromium, emerald-
| | green.
| | Vanadic Acid, emerald-green.
--+--------------------------------------+--------------------------------
Opaque-grey. (The opacity generally becomes distinct during cooling.)
--+--------------------------------------+--------------------------------
| _ |
| Oxide of Silver \ | Oxide of Silver._
| " " Zinc \ After | " " Zinc \ After
| " " Cadmium | short | " " Cadmium \short
| " " Lead } blowing. | " " Lead |blowing.
| " " Bismuth | Otherwise | " " Bismuth }Otherwise
| " " Antimony| colorless. | " " Antimony |colorless.
| " " Nickel / | " " Nickel /
| Telluric Acid _/ | Telluric Acid _/
| _ | _
| Niobic Acid \ After long | Niobic Acid\ After long
| Pelopic " | continued blowing | Pelopic " | continued
| } and in | } blowing and
| | considerable | | in considerable
| _/ proportion. | _/ proportion.
| |
--+--------------------------------------+--------------------------------
Opaque red and reddish-brown.
--+--------------------------------------+--------------------------------
| Oxide of Copper | Oxide of Copper.
--+--------------------------------------+--------------------------------
B. MICROCOSMIC SALT.
1. Oxydizing flame.
--+--------------------------------------+--------------------------------
Color of Bead.
--+-----------------------------------------------------------------------
| Substances which produce this color
+--------------------------------------+--------------------------------
| in the hot bead. | in the cold bead.
--+--------------------------------------+--------------------------------
Colorless
--+--------------------------------------+--------------------------------
| _ |
| Silica (only \ | Silica
| slightly soluble)\ |
| Alumina | | Alumina
| Oxide of Tin | | Oxide of Tin _
| Telluric Acid | | Telluric Acid \
| Baryta | | Baryta \
| Strontia | | Strontia |With
| Lime | In all | Lime |intermittent
| Magnesia } proportions. | Magnesia }flame
| Glucina | | Glucina |opaque
| Yttria | | Yttria |white.
| Zirconia | | Zirconia |
| Thoria | | Thoria /
| Oxide of Lanthanum | | Oxide of Lanthanum/
| | | " " Cerium
| Niobic Acid / | Niobic Acid
| Pelopic " _/ | Pelopic "
| Tantalic " | Tantalic "
| Titanic " | Titanic "
| Tungstic " _ | Tungstic "
| Oxide of Zinc \ In small | Oxide of Zinc
| " " Cadmium \ quantity only. | " " Cadmium
| " " Lead } In large | " " Lead
| " " Bismuth | quantity | " " Bismuth
| " " Antimony / yellow. | " " Antimony
| _/ |
--+--------------------------------------+--------------------------------
Yellow, orange, red and brown.
--+--------------------------------------+--------------------------------
| Tantalic Acid _ |
| Titanic " \ |
| Tungstic " | |
| Oxide of Zinc | In large |
| " " Cadmium } quantity. |
| " " Lead | |
| " " Bismuth | |
| " " Antimony _/ |
| " " Silver | Oxide of Silver.
| " " Cerium |
| " " Iron | Oxide of Iron.
| " " Nickel | " " Nickel.
| " " Uranium | " " Uranium,
| | yellowish-green.
| Vanadic Acid | Vanadic Acid.
| Oxide of Chromium |
--+--------------------------------------+--------------------------------
Violet or Amethyst.
--+--------------------------------------+--------------------------------
| Oxide of Manganese | Oxide of Manganese.
| " " Didymium | " " Didymium.
--+--------------------------------------+--------------------------------
Blue.
--+--------------------------------------+--------------------------------
| Oxide of Cobalt | Oxide of Cobalt
| | Oxide of Copper, to
| | greenish-blue.
--+--------------------------------------+--------------------------------
Green.
--+--------------------------------------+--------------------------------
| Molybdic Acid, yellowish-green | Molybdic Acid, yellowish-green.
| Oxide of Copper | Oxide of Uranium,
| | yellowish-green.
| | Oxide of Chromium,
| | emerald-green.
--+--------------------------------------+--------------------------------
B. MICROCOSMIC SALT.
2. Reducing flame.
--+--------------------------------------+--------------------------------
Color of Bead.
--+-----------------------------------------------------------------------
| Substances which produce this color
+--------------------------------------+---------------------------------
| in the hot bead. | in the cold bead.
--+--------------------------------------+--------------------------------
Colorless
--+--------------------------------------+--------------------------------
| Silica (only slightly soluble) | Silica (only slightly soluble).
| Alumina | Alumina.
| Oxide of Tin | Oxide of Tin. _
| Baryta | Baryta \
| Strontia | Strontia \
| Lime | Lime |
| Magnesia | Magnesia |With an
| Glucina | Glucina }intermittent
| Yttria | Yttria |flame
| Zirconia | Zirconia |opaque-
| Thoria | Thoria only when |white.
| | saturated /
| Oxide of Lanthanum | Oxide of Lanthanum/
| " " Cerium | " " Cerium.
| " " Didymium | " " Didymium.
| " " Manganese | " " Manganese.
| Tantalic Acid _ | Tantalic Acid.
| Oxide of Silver \ | Oxide of Silver _
| " " Zinc \ | " " Zinc \ After
| " " Cadmium | After long | " " Cadmium \ long
| " " Lead } continued | " " Lead | continued
| " " Bismuth | blowing. | " " Bismuth } blowing.
| " " Antimony | Otherwise grey. | " " Antimony | Otherwise
| " " Nickel / | " " Nickel / grey.
| Telluric Acid _/ | Telluric Acid _/
--+--------------------------------------+--------------------------------
Yellow, red, and brown.
--+--------------------------------------+--------------------------------
| Oxide of Iron, red | Oxide of Iron.
| Titanic Acid, yellow |
| Pelopic Acid, brown | Pelopic Acid.
| Ferruginous Titanic Acid, blood red | Ferruginous Titanic Acid.
| " Niobic " " | " Niobic "
| " Pelopic " " | " Pelopic "
| " Tungstic " " | " Tungstic "
| Vanadic Acid, brownish |
| Oxide of Chromium, reddish |
--+--------------------------------------+--------------------------------
Violet or Amethyst.
--+--------------------------------------+--------------------------------
| Niobic Acid in large proportion | Niobic Acid in large proportion.
| | Titanic Acid.
--+--------------------------------------+--------------------------------
Blue.
--+--------------------------------------+--------------------------------
| Oxide of Cobalt | Oxide of Cobalt.
| Tungstic Acid | Tungstic Acid.
| Niobic Acid in very large proportion.| Niobic Acid in very large
| | proportion.
--+--------------------------------------+--------------------------------
Green.
--+--------------------------------------+--------------------------------
| Oxide of Uranium | Oxide of Uranium.
| Molybdic Acid | Molybdic Acid.
| | Vanadic "
| | Oxide of Chromium.
--+--------------------------------------+--------------------------------
Opaque-grey. (The opacity generally becomes distinct during cooling.)
--+--------------------------------------+--------------------------------
| Oxide of Silver | Oxide of Silver.
| " " Zinc | " " Zinc.
| " " Cadmium | " " Cadmium.
| " " Lead | " " Lead.
| " " Bismuth | " " Bismuth.
| " " Antimony | " " Antimony.
| " " Nickel | " " Nickel.
| Telluric Acid | Telluric Acid.
--+--------------------------------------+--------------------------------
Opaque-red and reddish brown.
--+--------------------------------------+--------------------------------
| Oxide of Copper | Oxide of Copper.
--+--------------------------------------+--------------------------------
* * * * *
TABLE II.
Metallic Oxides
1. Oxide of Cerium, C^{2}O^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Dissolves into a red or dark yellow glass (similar to that
produced by iron). During cooling, the color diminishes in the
intensity and becomes finally yellow. If much oxide be dissolved,
an opaque bead may be obtained with an intermittent flame, and a
still larger quantity renders it opaque spontaneously.
in the reducing flame.
The color of the bead becomes paler, so that a bead, which is
yellow in the oxidizing flame, is rendered colorless. With a
large quantity of oxide the bead becomes white and crystalline
on cooling.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
As with borax. During the process of cooling the color entirely
disappears.
in the reducing flame.
Both, when hot and cold, the bead is colorless, by which
character oxide of cerium may be distinguished from oxide of
iron. The glass remains clear even when containing a large
quantity of the oxide.
* * * * *
2. Oxide of Lanthanum, LaO.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Dissolves into a colorless glass, which, when sufficient oxide
is present, may be rendered opaque with an intermittent flame,
and becomes so spontaneously on cooling, when a still larger
amount is dissolved.
in the reducing flame.
As in the oxidizing flame.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
As with borax.
in the reducing flame.
No reaction.
* * * * *
3. Oxide of Didymium, DO.
Behavior with Borax on Platinum wire
in the oxidizing flame:
Dissolves to a clear dark amethystine glass.
in the reducing flame.
No reaction.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
As with borax.
in the reducing flame.
No reaction.
* * * * *
4. Oxide of Manganese, Mn^{2}O^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Affords an intense amethyst color, which on cooling becomes
violet. A large quantity of the oxide produces an apparently
black bead, which however, if pressed flat, is seen to be
transparent.
in the reducing flame.
The colored bead becomes colorless. With a large amount of the
oxide, this reaction is best obtained upon charcoal, and is
facilitated by the addition of tin foil.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
With a considerable quantity of oxide an amethyst color is
obtained, but never so dark as in borax. With but little oxide a
colorless bead is obtained, in which, however, the
amethyst-color may be brought out by adding a little nitre.
While the bead is kept fused, it froths and gives off bubbles of
gas.
in the reducing flame.
The colored bead immediately loses its color, either on platinum
wire or on charcoal. After the reduction the fluid bead remains
still.
* * * * *
5. Oxide of Iron, Fe^{2}O^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
With a small proportion of oxide, the glass is of a yellow
color, while warm, and colorless when cold; with a larger
proportion, red, while warm, and yellow, when cold; and with a
still larger amount, dark-red, while warm, and dark-yellow, when
cold.
in the reducing flame.
Treated alone on platinum wire, the glass becomes of a
bottle-green color (F^{3}O^{4}), and if touched with tin, it
becomes of a pale sea-green. On charcoal with tin, it assumes at
first a bottle-green color, which by continued blowing changes
to a sea-green (FeO).
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
With a certain amount of oxide, the glass is of a yellowish-red
color, which on cooling changes to yellow, then green, and
finally becomes colorless. With a large addition of oxide, the
color is, when warm, dark red, and passes, while cooling, into
brownish-red, dark green, and finally brownish-red. During the
cooling process, the colors change more rapidly than with borax.
in the reducing flame.
With a small proportion of oxide there is no reaction. With a
larger amount the bead is red, while warm, and becomes on
cooling successively yellow, green, and russet. With the
addition of tin the glass becomes, during cooling, first green
and then colorless.
* * * * *
6. Oxide of Cobalt, CoO.
Behavior with Borax on Platinum wire
in the oxidizing flame:
Colors the glass of an intense smalt blue both whilst hot and
when cold. When much oxide is present, the color is so deep as
to appear black.
in the reducing flame:
As in the oxidizing flame.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
As with borax, but less intensively colored. During cooling the
color becomes somewhat paler.
in the reducing flame.
As in the oxidizing flames.
* * * * *
7. Oxide of Nickel, NiO.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Colors intensely. A small amount of oxide affords a glass which,
while warm, is violet, and becomes of a pale reddish-brown on
cooling. A larger addition produces a dark violet color in the
warm and reddish-brown in the cold bead.
in the reducing flame.
The oxide is reduced and the metallic particles give the bead a
turbid grey appearance. If the blast be continued the metallic
particles fall together without fusing, and the glass becomes
colorless. This reaction is readily obtained with tin upon
charcoal, and the reduced nickel fuses to a bead with the tin.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Dissolves into a reddish glass which becomes yellow on cooling.
With a large addition of the oxide, the glass is brownish while
hot, and orange when cold.
in the reducing flame.
On platinum wire the nickeliferous bead undergoes no change.
Treated with tin upon charcoal, it becomes at first opaque and
grey, and after long continued blowing the reduced nickel forms
a bead, and the glass remains colorless.
* * * * *
8. Oxide of Zinc, ZnO.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Dissolves easily into a clear colorless glass, which, when much
oxide is present, may be rendered opaque and flocculent by an
intermittent flame, and becomes so spontaneously with a still
larger addition. When a considerable quantity is dissolved, a
glass is obtained which is pale yellow, while hot, and colorless
when cold.
in the reducing flame.
On platinum wire the saturated glass becomes at first opaque and
grey, but by a sustained blast is again rendered clear. On
charcoal the oxide is gradually reduced; the metal is
volatilized and in crusts the charcoal with oxide.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
As with borax.
in the reducing flame.
As with borax.
* * * * *
9. Oxide of Cadmium, CdO.
Behavior with Borax on Platinum wire
in the oxidizing flame.
When in very large proportion, dissolves to a clear yellow
glass, which becomes nearly colorless on cooling. When the oxide
is present in any considerable quantity, the glass can be
rendered opaque with an intermittent flame, and, with a larger
addition, it becomes so spontaneously on cooling.
in the reducing flame.
Upon charcoal ebullition takes place and the oxide is reduced.
The metallic cadmium is volatilized and incrusts the charcoal
with its characteristic deep yellow oxide.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
When in very large proportion dissolves to a clear glass, having
a yellow tinge, while hot, which disappears on cooling, and when
perfectly saturated, becomes milk-white.
in the reducing flame.
On charcoal the oxide is slowly and imperfectly reduced. The
reduced metal forms the characteristic incrustation on the
charcoal, but the is thin and does not exhibit its color clearly
until quite cold. The addition of tin hastens the reaction.
* * * * *
10. Oxide of Lead, PbO.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Dissolves readily to a clear yellow glass, which loses its color
upon cooling, and when containing much oxide can be rendered
dull under an intermittent flame. With a still larger addition
of oxide it becomes opaline yellow on cooling.
in the reducing flame.
The plumbiferous glass spreads out on charcoal, becomes turbid,
bubbles up, until the whole of the oxide is reduced, when it
again becomes clear. It is, however, difficult to bring the lead
together into a bead.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
As with borax, but a larger addition of oxide, required to
produce a yellow color in the warm bead.
in the reducing flame.
On charcoal the plumbiferous glass becomes grey and dull. With
an over dose of oxide a part is volatilized and forms an
incrustation on the charcoal beyond the bead. The addition of
tin does not render the glass opaque, but somewhat more dull and
grey than in its absence.
* * * * *
11. Oxide of Tin, SnO^{2}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
In small quantity dissolves slowly into a clear colorless glass,
which, when cold, remains clear, and cannot be rendered opaque
with an intermittent flame. If a saturated bead, which has been
allowed to cool, be reheated to incipient redness, it loses its
rounded form and exhibits imperfect crystallization.
in the reducing flame.
A glass containing but little oxide undergoes no change. If much
of the latter be present, a part may be reduced upon charcoal.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
In small quantity dissolves very slowly to a colorless glass,
which remains clear on cooling.
in the reducing flame.
The glass undergoes no change, either on charcoal or platinum wire.
* * * * *
12. Oxide of Bismuth, BiO^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Dissolves readily to a clear glass which with a small amount of
the oxide is yellow, while warm, and becomes colorless on
cooling. With a larger addition, the glass is, in the hot state,
of a deep orange color, which changes to yellow and finally
becomes opaline in process of cooling.
in the reducing flame.
A glass becomes at first grey and turbid, then begins to
effervesce, which action continues during the reduction of the
oxide, and it finally becomes perfectly clear. If tin be added,
the glass becomes at first grey from the reduced bismuth, but,
when the metal is collected into a bead, the glass is again
clear and colorless.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Dissolves in small quantity to a clear colorless glass. A larger
addition affords a glass which, while warm, is yellow, and
becomes colorless on cooling. When in sufficient proportion the
glass may be rendered opaque under an intermittent flame, and a
still larger addition of oxide renders the bead spontaneously
opaque on cooling.
in the reducing flame.
On charcoal, and especially with the addition of tin, the glass
remains colorless and clear, while warm, but becomes on cooling
of a dark grey color and opaque.
* * * * *
13. Oxide of Uranium, U^{2}O^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Behaves similarly to oxide of iron, with the exception that the
color of the former is somewhat paler. When sufficiently
saturated, the glass may be rendered of an opaque yellow by an
intermittent flame.
in the reducing flame.
Affords the same color as the oxide of iron. The green glass
obtained in this flame, if sufficiently saturated, can be
rendered black by an intermittent flame, but it has under these
circumstances no enameline appearance. On charcoal, with the
addition of tin, the glass takes a dark green color.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Dissolves to a clear yellow glass, which assumes a
yellowish-green color on cooling.
in the reducing flame.
The glass assumes a beautiful green color, which becomes more
brilliant as the bead cools. The addition of tin upon charcoal
produces no further change.
* * * * *
14. Oxide of Copper, CuO.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Produces an intense coloration. If in small quantity, the glass
is green, while warm, and becomes blue on cooling. If in large
proportion, the green color is so intense as to appear black.
When cool, this becomes paler, and changes to a greenish blue.
in the reducing flame.
If not too saturated, the cupriferous glass soon becomes nearly
colorless, but immediately on solidifying assumes a red color
and becomes opaque. By long continued blowing on charcoal, the
copper in the bead is reduced and separates out as a small
metallic bead, leaving the glass colorless. With the addition of
tin, the glass becomes of an opaque dull-red on cooling.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
With an equal proportion of oxide, this salt is not so strongly
colored as borax. A small amount imparts a green color in the
warm and a blue in the cold. With a very large addition of
oxide, the glass is opaque in the hot state, and after cooling
of a greenish-blue.
in the reducing flame.
A tolerably saturated glass assumes a dark green color under a
good flame, and on cooling becomes of an opaque brick-red, the
moment it solidifies. A glass containing but a small proportion
of the oxide becomes equally red and opaque on cooling, if
treated with tin upon charcoal.
* * * * *
15. Oxide of Mercury, HgO.
Behavior with Borax on Platinum wire
in the oxidizing flame.
No reaction.
in the reducing flame.
No reaction.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
No reaction.
in the reducing flame.
No reaction.
* * * * *
16. Oxide of Silver, AgO.
Behavior with Borax on Platinum wire
in the oxidizing flame.
The oxide is partly dissolved and partly reduced. In small
quantity, it colors the glass yellow while warm, the color
disappearing on cooling. In larger quantity, the glass is yellow
while warm, but during cooling becomes paler to a certain point,
and then again deeper. If reheated slightly, the glass becomes
opalescent.
in the reducing flame.
On charcoal the argentiferous glass becomes at first grey from
the reduced metal, but afterwards, when the silver is collected
into a bead, it becomes clear and colorless.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Both the oxide and the metal afford a yellowish glass, which,
when containing much oxide becomes opaline, exhibiting a yellow
color by daylight and a red one by artificial light.
in the reducing flame.
As in borax.
* * * * *
17. Oxide of Platinum, PtO^{2}.
18. Oxide of Palladium, PdO^{2}.
19. Oxide of Rhodium, R^{2}O^{3}.
20. Oxide of Iridium, Ir^{2}O^{3}.
21. Oxide of Ruthenium, Ru^{2}O^{9}.
22. Oxide of Osmium OsO^{2}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Are reduced without being dissolved. The reduced metal, being
infusible, cannot however be collected into a bead.
in the reducing flame.
As in the oxidizing flame.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
As in borax.
in the reducing flame.
As in borax.
* * * * *
23. Oxide of Gold, Au^{2}O^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Is reduced without being dissolved and can be collected into a
bead on charcoal.
in the reducing flame.
As in the oxidizing flame.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
As in borax.
in the reducing flame.
As in borax.
* * * * *
24. Titanic Acid, TiO^{2}
Behavior with Borax on Platinum wire
in the oxidizing flame.
Dissolves readily to a clear glass which, when but little acid
is present, is colorless, but when in larger proportion, yellow,
and, on cooling, colorless. When sufficiently saturated, it may
be rendered opaque with an intermittent flame, and with a still
larger addition of the acid becomes so spontaneously on cooling.
in the reducing flame.
In small proportion, it renders the glass yellow in larger
quantity dark-yellow or brown. A saturated bead assumes a
blue enamel-like appearance under an intermittent flame.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Dissolves readily to a clear glass, which, when sufficiently
saturated, is yellow white hot, and becomes colorless on
cooling.
in the reducing flame.
The glass obtained in the oxidizing glame becomes yellow in the
hot state, but on cooling assumes a beautiful violet color. If
too saturated, this color is so deep as to appear opaque, but is
not enameline. If the titanic acid contains iron, the glass
becomes on cooling of a brownish-yellow or red color. The
addition of tin neutralizes the iron, and the glass then becomes
violet.
* * * * *
25. Tantalic Acid, TaO^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Dissolves readily to a clear colorless glass, which, when
sufficiently saturated, may be rendered opaque with an
intermittent flame, and with a larger addition of the acid
becomes spontaneously enameline on cooling.
in the reducing flame.
As in the oxidizing flame.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Dissolves readily to a clear glass, which, when it contains a
large proportion of the acid, is yellow while warm, but becomes
colorless on cooling.
in the reducing flame.
The glass obtained in the oxidizing flame undergoes no change,
nor does it, according to _H. Rose_, alter by the addition of
sulphate of iron.
* * * * *
26. Niobic Acid, Ni^{2}O{3}
Behavior with Borax on Platinum wire
in the oxidizing flame.
Behaves in a similar manner to tantalic acid, but the glass
requires a very large dose of the acid to render it opaque under
an intermittent flame. With an increased amount of the acid, the
glass is clear and yellow, while warm, but becomes on cooling
turbid, and when quite cold is white.
in the reducing flame.
The glass obtained in the oxidizing flame and which has become
opalescent on cooling, is rendered clear in the reducing flame.
With a larger addition of the acid, it becomes dull, and of a
bluish-grey color on cooling, and a still larger amount of
renders it opaque and bluish grey.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Dissolves in large quantities to a clear colorless glass.
in the reducing flame.
If the acid be not present in too large a proportion, the glass
remains unchanged. An additional amount of the acid renders it
violet, and a still larger quantity affords a beautiful pure
blue color, similar to that produced by tungstic acid. If to
such a bead some sulphate of iron be added, the glass becomes
blood-red. The addition of peroxide of iron renders the glass
deep yellow while warm, the color becomes paler on cooling.
* * * * *
27. Pelopic Acid, Pp^{2}O^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Behaves similarly to the preceding.
in the reducing flame.
A bead containing sufficient of the acid to render it
spontaneously opaque on cooling, has a greyish color.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Dissolves even in large quantity to a colorless glass.
in the reducing flame.
With sufficient dose of the acid, the bead becomes brown with a
violet tinge. This reaction is readily obtained upon charcoal.
Sulphate of iron renders the bead blood-red.
* * * * *
28. Oxide of Antimony, SbO^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Even when in large proportion, dissolves to a clear glass, which
is yellow when warm, but almost entirely loses its color on
cooling. On charcoal, the antimonious acid may be almost
expelled, so that tin produces no further change.
in the reducing flame.
A bead, that has only been treated for a short time in the
oxidizing flame, when submitted to the reducing flame becomes
grey and turbid from the reduced antimony. This soon volatizes
and the glass again becomes clear. The addition of tin renders
the glass ash-grey or black, according to the amount of oxide it
contains.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Dissolves with ebullition to a glass of a pale yellow color
while warm.
in the reducing flame.
On charcoal, the saturated glass becomes at first dull, but as
soon as the reduced antimony is volatilized, it again becomes
clear. With tin, the glass is at first rendered grey by the
reduced antimony, but by continued blowing is restored to
clearness. Even when the glass contains but little oxide, tin
produces this reaction.
* * * * *
29. Tungstic Acid, WO^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Dissolves readily to a clear colorless glass. In large
proportion it renders the borax yellow, while warm, and with a
still greater addition the bead may be made opaque with an
intermittent flame. If more be then added, this reaction takes
place spontaneously.
in the reducing flame.
When the oxide is present in small quantity, the glass undergoes
no change. With a larger proportion, the glass is deep yellow
while warm, and yellowish-brown when cold. This reaction takes
place upon charcoal, with a small quantity of the acid. Tin
produces a dark coloration, when the acid is not present in too
great a quantity.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Dissolves to a clear glass, which, when saturated, is yellow in
the hot state.
in the reducing flame.
The glass is of a pure blue. If the tungstic acid contain iron,
the glass becomes blood-red on cooling, similar to titanic acid.
In this case, tin restores the blue color, or, if iron be in
considerable quantity, renders it green.
* * * * *
30. Molydbic Acid, MO^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Dissolves readily and in large quantity. When but little is
dissolved, the glass is yellow while hot and colorless when
cold. When in larger quantity yellow while warm and opaline when
cold, and a further addition of acid renders it yellow when
warm, the color, on cooling, changing first to a pale enamel
blue, and then to an enamel white.
in the reducing flame.
The glass, which has been treated in the oxidizing flame,
becomes, when the acid is not present in too large a quantity,
brown, and when in large quantity, perfectly opaque. In a
strong flame, oxide of molybdenum is formed which is visible in
the yellow glass in the form of black flakes. If the glass
appear opaque, it should be flattened with the forceps.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Dissolves to a clear glass, which, when sufficient acid is
present, is of a yellowish-green color when warm, and becomes
nearly colorless on cooling. On charcoal, the glass becomes
dark, and when cool has a beautiful green color.
in the reducing flame.
The glass becomes of a bottle-green color, which on cooling,
changes to a brilliant green, similar to that produced by oxide
of chromium. The reaction on charcoal is precisely similar. Tin
renders the color somewhat darker.
* * * * *
31. Vanadic Acid, VaO^{8}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Dissolves to a clear glass, which is colorless when only a small
quantity of acid is present, and yellow when containing a larger
proportion.
in the reducing flame.
The yellow color of the glass changes to a brown when warm and a
chrome-green on cooling.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
As with borax.
in the reducing flame.
As with borax.
* * * * *
32. Oxide of Chromium, Cr^{2}O^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Affords an intense color, but dissolves slowly. A small
proportion colors the glass yellow when warm, and yellowish
green when cold; a larger addition produces a dark red color
when warm, which, on cooling, becomes yellow and finally a
brilliant green with a tinge of yellow.
in the reducing flame.
A small quantity of the oxide renders the glass beautifully
green both when warm and when cold. A larger addition changes it
to a darker emerald green. Tin produces no change in the color.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
Dissolves to a clear glass which has a pink tinge while warm,
but on cooling becomes dusky green, and finally brilliantly
green.
in the reducing flame.
As in the oxidizing flame, except that the colors are somewhat
darker. Tin produces no further change.
* * * * *
33. Arsenious Acid, AsO^{3}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
No reaction.
in the reducing flame.
No reaction.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
No reaction.
in the reducing flame.
No reaction.
* * * * *
34. Tellurous Acid, TeO^{2}.
Behavior with Borax on Platinum wire
in the oxidizing flame.
Dissolves to a clear colorless glass which, when treated on
charcoal, becomes grey and dull from particles of reduced
tellurium.
in the reducing flame.
As in the oxidizing flame.
Behavior with Mic. Salt on Platinum wire
in the oxidizing flame.
As with borax.
in the reducing flame.
As with borax.
* * * * *
7. EXAMINATIONS WITH CARBONATE OF SODA.
The carbonate of soda is pulverized and then kneaded to a paste with
water; the substance to be examined, in fine powder, is also mixed
with it. A small portion of this paste is placed on the charcoal, and
gradually heated until the moisture is expelled, when the heat is
brought to the fusion of the bead, or as high as it can be raised.
Several phenomena will take place, which must be closely observed.
Notice whether the substance fuses with the bead, and if so, whether
there is intumescence or not. Or, whether the substance undergoes
reduction; or, whether neither of these reactions takes place, and, on
the contrary, the soda sinks into the charcoal, leaving the substance
intact upon its surface. If intumescence takes place, the presence of
either tartaric acid, molybdic acid, silicic, or tungstic acid, is
indicated. The silicic acid will fuse into a bead, which becomes clear
when it is cold. Titanic acid will fuse into the bead, but may be
easily distinguished from the silicic acid by the bead remaining
opaque when cold.
Strontia and baryta will flow into the charcoal, but lime will not.
The molybdic and tungstic acids combine with the soda, forming the
respective salts. These salts are absorbed by the charcoal. If too
great a quantity of soda is used, the bead will be quite likely to
become opaque upon cooling, while, if too small a quantity of soda is
used, a portion of the substance will remain undissolved. These can be
equally avoided by either the addition of soda, or the substance
experimented upon, as may be required.
As silica and titanic acid are the only two substances that produce a
clear bead, the student, if he gets a clear bead, may almost conclude
that he is experimenting with silica, titanic acid being a rare
substance. When soda is heated with silica, a slight effervescence
will be the first phenomenon noticed. This is the escape of the
carbonic acid of the carbonate of soda, while the silicic acid takes
its place, forming a glass with the soda. As titanic acid will not
act in the same manner as silica, it can be easily distinguished by
its bead not being perfectly pellucid. If the bead with which silica
is fused should be tinted of a hyacinth or yellow color, this may be
attributed to the presence of a small quantity of sulphur or a
sulphate, and this sometimes happens from the fact of the flux
containing sulphate of soda. The following metals, when exposed with
carbonate of soda to the reducing flame, are wholly or partially
reduced, viz. the oxides of all the noble metals, the oxides and acids
of tungsten, molybdenum, arsenic, antimony, mercury, copper,
tellurium, zinc, lead, bismuth, tin, cadmium, iron, nickel, and
cobalt. Mercury and arsenic, as soon as they are reduced, are
dissipated, while tellurium, bismuth, lead, antimony, cadmium, and
zinc, are only partially volatilized, and, therefore, form sublimates
on the charcoal. Those metals which are difficult of reduction should
be fused with oxalate of potassa, instead of the carbonate of soda.
The carbonic oxide formed from the combustion of the acid of this salt
is very efficient in the reduction of these metals. Carbonate of soda
is very efficient for the detection of minute quantities of manganese.
The mixture of the carbonate of soda with a small addition of nitrate
of potassa, and the mineral containing manganese, must be fused on
platinum foil. The fused mass, when cooled, presents a fine blue
color.
* * * * *
1. The following minerals, according to Griffin, produce beads with
soda, but do not fuse when heated alone: quartz, agalmatolyte,
dioptase, hisingerite, sideroschilosite, leucite, rutile,
pyrophyllite, wolckonskoite.
2. The following minerals produce only slags with soda: allophane,
cymophane, polymignite, æschynite, oerstedtite, titaniferous iron,
tantalite, oxides of iron, yttro-tantalite, oxides of manganese,
peroxide of tin (is reduced), hydrate of alumina, hydrate of magnesia,
spinel, gahnite, worthite, carbonate of zinc, pechuran, zircon,
thorite, andalusite, staurolite, gehlenite, chlorite spar, chrome
ochre, uwarowite, chromate of iron, carbonates of the earths,
carbonates of the metallic oxides, basic phosphate of yttria, do. of
alumina, do. of lime, persulphate of iron, sulphate of alumina,
aluminite, alumstone, fluoride of cerium, yttrocerite, topaz,
corundum, pleonaste, chondrodite.
3. The following minerals produce beads with a small quantity of soda,
but produce slags if too much soda is added: phenakite, pierosmine,
olivine, cerite, cyanite, talc, gadolinite, lithium-tourmaline.
* * * * *
1. The following minerals, when fused alone, produce beads. Of these
minerals the following produce beads with soda: the zeolites,
spodumene, soda-spodumene, labrador, scapolite, sodalite (Greenland),
elæolite, mica from primitive lime-stone, black talc, acmite,
krokidolite, lievrite, cronstedtite, garnet, cerine, helvine,
gadolinite, boracic acid, hydroboracite, tincal, boracite, datholite,
botryolite, axinite, lapis lazuli, eudialyte, pyrosmalite, cryolite.
2. The following minerals produce beads with a small quantity of soda,
but if too much is added they produce slags: okenite, pectolite, red
silicate of manganese, black hydro-silicate of manganese, idocrase,
manganesian garnets, orthite, pyrorthite, sordawalite, sodalite,
fluorspar.
3. The following minerals produce a slag with soda: brevicite,
amphodelite, chlorite, fahlunite, pyrope, soap-stone (Cornish) red
dichroite, pyrargillite, black potash tourmaline, wolfram,
pharmacolite, scorodite, arseniate of iron, tetraphyline, hetepozite,
uranite, phosphate of iron, do. of strontia, do. of magnesia,
polyhalite, hauyne.
4. The following metals are reduced by soda: tungstate of lead,
molybdate of lead, vanadate of lead, chromate of lead, vauquelinite,
cobalt bloom, nickel ochre, phosphate of copper, sulphate of lead,
chloride of lead, and chloride of silver.
* * * * *
The following minerals fuse on the edges alone, when heated in the
blowpipe flame:
1. The following produce beads with soda: steatite, meerschaum,
felspar, albite, petalite, nepheline, anorthite, emerald, euclase,
turquois, sodalite (Vesuvius).
2. The following minerals produce beads with a small quantity of
soda, but with the addition of more produce slags: tabular spar,
diallage, hypersthene, epidote, zoisite.
3. The following minerals produce slags only with soda:
stilpnosiderite, plombgomme, serpentine, silicate of manganese (from
Piedmont), mica from granite, pimelite, pinite, blue dichroite,
sphenc, karpholite, pyrochlore, tungstate of lime, green soda
tourmaline, lazulite, heavy spar, gypsum.
* * * * *
The reactions of substances, when fused with soda in the flame of
oxidation may be of use to the student. A few of them are therefore
given. Silica gives a clear glass.
The oxide of tellurium and telluric acid gives a clear bead when it is
hot, but white after it is cooled.
Titanic acid gives a yellow bead when hot.
The oxide of chromium gives also a clear yellow glass when hot, but is
opaque when cold.
Molybdic acid gives a clear bead when hot, but is turbid and white
after cooling.
The oxides and acids of antimony give a clear and colorless bead while
hot, and white after cooling.
Vanadic acid is absorbed by the charcoal, although it is not reduced.
Tungstic acid gives a dark yellow clear bead while hot, but is opaque
and yellow when cold.
The oxides of manganese give to the soda bead a fine characteristic
green color. This is the case with a very small quantity. This
reaction is best exhibited on platinum foil.
Oxide of cobalt gives to the bead while hot a red color, which, upon
being cooled, becomes grey.
The oxide of copper gives a clear green bead while hot.
The oxide of lead gives a clear colorless bead while hot, which
becomes, upon cooling, of a dirty yellow color and opaque.
* * * * *
The following metals, when they are fused with soda on charcoal, in
the flame of reduction, produce volatile oxides, and leave an
incrustation around the assay, viz. bismuth, zinc, lead, cadmium,
antimony, selenium, tellurium, and arsenic.
_Bismuth_, under the reduction flame, yields small particles of metal,
which are brittle and easily crushed. The incrustation is of a flesh
color, or orange, when hot, but gets lighter as it cools. The
sublimate may be driven about the charcoal from place to place, by
either flame, but is finally dissipated. While antimony and tellurium,
in the act of dissipation, give color to the flame, bismuth does not,
and may thus be distinguished from them.
_Zinc_ deposits an incrustation about the assay, which is yellow while
hot, but fades to white when cold. The reduction flame dissipates this
deposit, but not that of oxidation. All the zinc minerals deposit the
oxide incrustation about the assay, which, when moistened with a
solution of cobalt and heated, changes to green.
_Lead_ is very easily reduced, in small particles, and may be easily
distinguished by its flattening under the hammer, unlike bismuth. It
leaves an incrustation around the assay resembling that of bismuth, in
the color of it, and in the peculiar manner in which it lies around
the assay.
_Cadmium_ deposits a dull reddish incrustation around the assay.
Either of the flames dissipate the sublimate with the greatest
readiness.
_Antimony_ reduces with readiness. At the same time it yields
considerable vapor, and deposits an incrustation around the assay.
This deposit can be driven about on the charcoal by either of the
flames. The flame of reduction, however, produces the light blue color
of the antimony.
_Selenium_ is deposited on the charcoal as a grey metallic-looking
sublimate, but sometimes appearing purple or blue. If the reduction
flame is directed on this deposit, it is dissipated with a blue light.
_Tellurium_ is deposited on the charcoal as a white sublimate,
sometimes changing at the margin to an orange or red color. The
oxidation flame drives the deposit over the charcoal, while the
reduction-flame dissipates it with a greenish color.
_Arsenic_ is vaporized rapidly, while there is deposited around the
assay a white incrustation of arsenious acid. This deposit will extend
to some distance from the assay, and is readily volatilized, the
reducing flame producing the characteristic alliaceous color.
* * * * *
The following metals, or their compounds, are reduced when fused with
soda on charcoal, in the flame of reduction. They are reduced to
metallic particles, but give no incrustation, viz. nickel, cobalt,
iron, tin, copper, gold, silver, platinum, tungsten, and molybdenum.
The particles of iron, nickel, and cobalt, it should be borne in mind,
are attracted by the magnet.
The following substances are neither fused nor reduced in soda, viz.
alumina, magnesia, lime, baryta, strontia, the oxide of uranium, the
oxides of cerium, zirconia, tantalic acid, thorina, glucina, and
yttria. Neither are the alkalies, as they sink into the charcoal. The
carbonates of the earths, strontia, and baryta fuse.
* * * * *
Part III
SPECIAL REACTIONS; OR, THE BEHAVIOR OF SUBSTANCES BEFORE THE BLOWPIPE.
Analytical chemistry may be termed the art of converting the unknown
constituents of substances, by means of certain operations, into new
combinations which we recognize through the physical and chemical
properties which they manifest.
It is, therefore, indispensably necessary, not only to be cognizant of
the peculiar conditions by which these operations can be effected, but
it is absolutely necessary to be acquainted with the forms and
combinations of the resulting product, and with every modification
which may be produced by altering the conditions of the analysis.
We shall first give the behavior of simple substances before the
blowpipe; and the student should study this part thoroughly, by
repeating each reaction, so that he can acquire a knowledge of the
color, form, and physical properties in general, of the resulting
combination. There is nothing, perhaps, which will contribute more
readily to the progress of the pupil, than thorough practice with the
reactions recommended in this part of the work, for when once the
student shall have acquired a practical eye in the discernment of the
peculiar appearances of substances after they have undergone the
decompositions produced by the strong heat of the blowpipe flame,
together with the reactions incident to these changes, then he will
have greatly progressed in his study, and the rest will be
comparatively simple.
A. METALLIC OXIDES.
GROUP FIRST.--THE ALKALIES: POTASSA, SODA, AMMONIA, AND LITHIA.
The alkalies, in their pure, or carbonated state, render reddened
litmus paper blue. This is likewise the case with the sulphides of the
alkalies. The neutral salts of the alkalies, formed with the strong
acids, do not change litmus paper, but the salts formed with the weak
acids, render the red litmus paper blue; for instance, the alkaline
salts with boracic acid. Fused with borax, soda, or microcosmic salt,
they give a clear bead. The alkalies and their salts melt at a low red
heat. The alkalies cannot be reduced to the metallic state before the
blowpipe. They are not volatile when red hot, except the alkali
ammonia, but they are volatile at a white heat.
(_a._) _Potassa._(KO).--It is not found free, but in combination with
inorganic and organic acids, as well in the animal as in the vegetable
organism, as in the mineral kingdom. In the pure, or anhydrous state,
or as the carbonate, potassa absorbs moisture, and becomes fluid, or
is deliquescent, as it is termed. By exposing potassa, or its easily
fusible salts (except the phosphate or borate), upon platinum wire, to
the point of the blue flame, there is communicated to the external
flame a violet color, in consequence of a reduction and reoxidation.
This color, though characteristic of all the potassa compounds, is
scarcely visible with the phosphate or borate salts of that alkali.
The admixture of a very little soda (1/300th) destroys the color
imparted by the potassa, while the flame assumes a yellow color,
characteristic of the soda. The presence of lithia changes the violet
color of the potash into red. The silicates of potassa must exist in
pretty large proportion before they can be detected by the violet
color of the flame, and those minerals must melt easily at the edges.
The presence of a little soda in these instances conceals the reaction
in the potassa entirely.
If alcohol is poured over potassa compounds which are powdered, and
then set on fire, the external flame appears violet-colored,
particularly when stirred with a glass rod, and when the alcohol is
really consumed. The presence of soda in lithia will, in this case
likewise, hide by their own characteristic color, that of the potassa.
The salts of potassa are absorbed when fused upon charcoal. The
sulphur, bromine, chlorine, and iodine compounds of potassa give a
white, but easily volatile sublimate upon the charcoal, around the
place where the fused substance reposed. This white sublimate
manifests itself only when the substance is melted and absorbed within
the charcoal, and ceases to be visible as soon as it is submitted to
the reducing flame, while the external flame is colored violet;
sulphate of potassa, for instance, is reduced by the glowing charcoal
into the sulphide. This latter is somewhat volatile, but by passing
through the oxidation flame, it is again oxidized into the sulphate.
This, being less volatile, sublimes upon the charcoal, but by exposing
it again to the flame of reduction, it is reduced and carried off to
be again oxidized by its passage through the oxidation flame.
Potassa and its compounds give, with soda, borax or microcosmic salt,
as well when hot as cold, colorless beads, unless the acid associated
with the alkali should itself produce a color. When borax is fused
with some pure boracic acid, and sufficient of the oxide of nickel is
added, so that the beads appear of a brown color after being cooled,
and then the bead thus produced fused with the substance suspected to
contain potassa, in the oxidation flame, the brown color is changed to
blue. The presence of the other alkalies does not prevent this
reaction. As it is not possible to detect potassa compounds with
unerring certainty by the blowpipe flame, the the wet method should
be resorted to for the purpose of confirming it.
The _silicates of potassa_ must be prepared as follows, for analytical
purposes by the wet way. Mix one part of the finely powdered substance
with two parts of soda (free from potassa), and one part of borax.
Fuse the mixture upon charcoal in the oxidation flame to a clear,
transparent bead. This is to be exposed again with the pincers to the
oxidation flame, to burn off the adhering coal particles. Then
pulverize and dissolve in hydrochloric acid to separate the silica;
evaporate to dryness, dissolve the residue in water, with the
admixture of a little alcohol, and test the filtrate with chloride of
platinum for potassa.
(_b._) _Soda_ (NaO).--This is one of the most abundant substances,
although seldom found free, but combined with chlorine or some other
less abundant compound. Soda, its hydrate and salts manifest in
general the same properties as their respective potash compounds; but
the salts of soda mostly contain crystal water, which leaves the salts
if they are exposed to the air, and the salts effervesce.
By exposing soda or its compounds upon a platinum wire to the blue
flame, a reddish-yellow color is communicated to the external flame,
which appears as a long brilliant stream and considerably increased in
volume. The presence of potash does not prevent this reaction of soda.
If there is too large a quantity of potash, the flame near to the
substance is violet-colored, but the edge of the flame exhibits the
characteristic tint of the soda. The presence of lithia changes the
yellow color to a shade of red.
When alcohol is poured over powdered soda compounds and lighted, the
flame exhibits a reddish-yellow color, particularly if the alcohol is
stirred up with a glass rod, or if the alcohol is nearly consumed.
Fused upon charcoal, soda compounds are absorbed by the coal. The
sulphide, chloride, iodide, and bromide of soda yield a white
sublimate around the spot where the substance is laid, but this
sublimate is not so copious as that of the potash compounds, and
disappears when touched with the reduction flame, communicating a
yellow color to the external flame. The presence of soda in compounds
must likewise be confined by reactions in the wet way.
(_c._) _Ammonia_ (NH^{4}O).--In the fused state, and at the usual
temperature, ammonia is a pungent gas, and exerts a reaction upon
litmus paper similar to potash and soda. Ammonium is considered by
chemists as a metal, from the nature of its behavior with other
substances. It has not been isolated, but its existence is now
generally conceded by all chemists. The ammonia salts are volatile,
and many of them sublimate without being decomposed.
The salts of ammonia, on being heated in the point of the blue flame,
produce a feeble green color in the external flame, just previous to
their being converted into vapor. But this color is scarcely visible,
and presents nothing characteristic. When the ammonia salts are mixed
with the carbonate of soda, and heated in a glass tube closed at one
end, carbonate of ammonia is sublimed, which can be readily recognized
by its penetrating smell of spirits of hartshorn.
This sublimate will render blue a slip of red litmus paper. This can
be easily done by moistening the litmus paper, and then inserting the
end of it in the tube. By holding a glass rod, moistened with dilute
hydrochloric acid, over the mouth of the tube, a white vapor is
instantly rendered visible (sal ammoniac).
(_d._) _Lithia_ (LiO).--In the pure state, lithia is white and
crystalline, not easily soluble in water, and does not absorb
moisture. It changes red litmus to blue, and at a low red heat it
melts. Lithia or its salts, exposed to the point of the blue flame,
communicates a red color to the external or oxidation flame, in
consequence of a reduction, sublimation, and re-oxidation of the
lithia. An admixture of potash communicates to this flame a
reddish-violet color, and the presence of soda that of a yellowish-red
or orange. If the soda, however, is in too great proportion, then its
intense yellow hides the red of the lithia. In the latter case the
substance under test must be only imperfectly fused in the oxidation
flame, and then dipped in wax or tallow. By exposing it now to the
reduction flame, the red color imparted to the external flame by the
lithia becomes visible, even if a considerable quantity of soda be
present. A particular phenomenon appears with the phosphate of lithia,
viz., the phosphoric acid itself possesses the property of
communicating to the flame a bluish-green color. By its combination
with lithia it still exhibits its characteristic color, while the
latter presents likewise its peculiar tint. Then we perceive a green
flame in the centre of the flame, while the red color of lithia
surrounds it.
The _silicates_, which contain only a little lithia, produce only a
slight hue in the flame, and often none at all. We have to mix one
part of the silicate with two parts of a mixture composed of one part
of fluorspar and one and a half parts of bisulphate of potassa.
Moisten the mass with water so that the mass will adhere, and then
melt it upon a platinum wire in the reduction flame, when that of
oxidation will present the red color of lithia.
The _Borates of lithia_ produce at first a green color, but it soon
yields to the red of lithia. When alcohol is poured over lithia or its
compounds, and inflamed, it burns with a deep red color, particularly
if the fluid is stirred up with a glass rod, or when the alcohol is
nearly consumed. This color presents the same modifications as the
corresponding ones communicated to the blowpipe as mentioned above.
The salts of lithia are absorbed by charcoal when fused upon it. The
sulphide, bromide, iodide, and chloride of lithia produce upon the
charcoal a greyish-white sublimate, although not so copiously as the
corresponding compounds of potash and soda. This sublimate disappears
when touched by the reduction flame, while the oxidation flame gives
the characteristic color of lithia.
SECOND GROUP.--THE ALKALINE EARTHS, BARYTA, STRONTIA, LIME, AND
MAGNESIA.
In the pure state, the alkaline earths are caustic, cause red litmus
paper to become blue, and are more or less soluble in water. Their
sulphides are also soluble. The carbonates and phosphates of the
alkaline earths are insoluble in water. By igniting the carbonates,
their carbonic acid is expelled, and the alkaline earths are left in
the caustic state. The alkaline earths are not volatile, and their
organic salts are converted, by ignition, into carbonates.
(_a._) _Baryta._ (BaO).--This alkaline earth does not occur free in
nature, but combined with acids, particularly with carbonic and
sulphuric acids. In the pure state, baryta is of a greyish-white
color, presents an earthy appearance, and is easily powdered. When
sparingly moistened with water, it slakes, becomes heated, and forms a
dry, white powder. With still more water it forms a crystalline mass,
the hydrate of baryta, which is completely soluble in hot water. Pure
baryta is infusible; the hydrate fuses at a red heat, without the loss
of its hydratic water; if caustic baryta is exposed for too great a
length of time to the flame, it absorbs water, originated by the
combustion, and becomes a hydrate, when it will melt. Salts of baryta,
formed with most acids, are insoluble in water; for instance, the
salts with sulphuric, carbonic, arsenic, phosphoric, and boracic
acids. The salts of baryta, soluble in water, are decomposed by
ignition, except the chloride.
Carbonate of baryta loses its carbonic acid at a red heat, becomes
caustic, and colors red litmus paper blue.
By exposing baryta or its compounds upon a platinum wire, or a
splinter of the substance held with the platinum tongs, to the point
of the blue flame, a pale apple-green color is communicated to the
external flame. This color appears at first very pale, but soon
becomes more intense. This color is most visible if the substance is
operated with in small quantities. The chloride of barium produces the
deepest color. This color is less intense if the carbonate or sulphate
is used. The presence of strontia, lime, or magnesia, does not
suppress the reaction of the baryta, unless they greatly predominate.
When alcohol is poured over baryta or its salts, and inflamed, a
feeble green color is communicated to the flame, but this color should
not be considered a characteristic of the salt.
Baryta and its compounds give, when fused with carbonate of soda upon
platinum foil, a clear bead. Fused with soda upon charcoal, it is
absorbed. The sulphate fuses at first to a clear bead, which soon
spreads, and is absorbed and converted while boiling into a hepatic
mass. If this mass is taken out, placed upon a piece of polished
silver and moistened with a little water, a black spot of sulphide of
silver is left after washing off the mass with water.
Borax dissolves baryta and its compounds with a hissing noise, as well
in the flame of oxidation as in that of reduction. There is formed a
clear bead which, with a certain degree of saturation, is clear when
cold, but appears milk-white when overcharged, and of an opal, enamel
appearance, when heated intermittingly, or with a vacillating flame,
that changes frequently from the oxidating to the reducing flame.
Baryta and its compounds produce the same reactions with microcosmic
salt.
Baryta and its compounds fuse when exposed to ignition in the
oxidizing flame. Moistened with the solution of nitrate of cobalt, and
heated in the oxidation flame, it presents a bead, colored from
brick-red to brown, according to the quantity used. This color
disappears when cold, and the bead falls to a pale grey powder after
being exposed awhile to the air. When heated again, the color does not
appear until fusion is effected. If carbonate of soda is fused upon
platinum wire with so much of the sesquioxide of manganese that a
green bead is produced, this bead, when fused with a sufficient
quantity of baryta, or its compounds, after cooling, will appear of a
bluish-green, or light blue color.
(_b._) _Strontia_ (SrO).--Strontia and its compounds are analogous to
the respective ones of baryta. The hydrate of strontia has the same
properties as the hydrate of baryta, except that it is less soluble in
water. The carbonate of strontia fuses a little at a red heat, swells,
and bubbles up like cauliflower. This produces, in the blowpipe flame,
an intense and splendid light, and now produces an alkaline reaction
upon red litmus paper. The sulphate of strontia melts in the oxidation
flame upon platinum foil, or upon charcoal, to a milk-white globule.
This fuses upon charcoal, spreads and is reduced to the sulphide,
which is absorbed by the charcoal. It now produces the same reactions
upon polished silver as the sulphate of baryta under the same
conditions. By exposing strontia and its compounds upon platinum wire,
or as a splinter with the platinum tongs, to the point of the blue
flame, the external flame appears of an intense crimson color. The
deepest red color is produced by the chloride of strontium,
particularly at the first moment of applying the heat. After the salt
is fused, the red color ceases to be visible in the flame, by which it
is distinguished from the chloride of lithium. The carbonate of
strontia swells up and produces a splendid white light, while the
external flame is colored of a fine purple-red. The color produced by
the sulphate of strontia is less intense. The presence of baryta
destroys the reaction of the strontia, the flame presenting the light
green color of the baryta.
If alcohol is poured over powdered strontia and inflamed, the flame
appears purple or deep crimson, particularly if the fluid is stirred
with a glass rod, and when the alcohol is nearly consumed.
The insoluble salts of strontia do not produce a very intense color.
Baryta does not prevent the reaction of the soluble salts of strontia,
unless it exists greatly in excess. In the presence of baryta,
strontia can be detected by the following process: mix some of the
substance under examination with some pure graphite and water, by
grinding in an agate mortar. Place the mixture upon charcoal, and
expose it for a while to the reduction flame. The substance becomes
reduced to sulphide of barium and sulphide of strontium, when it
should be dissolved in hydrochloric acid. The solution should be
evaporated to dryness, redissolved in a little water, and enough
alcohol added that a spirit of 80 per cent. is produced. Inflame the
spirit, and if strontia is present, the flame is tinged of a red
color. This color can be discerned more distinctly by moistening some
cotton with this spirit and inflaming it.
If strontia or its compounds are fused with a green bead of carbonate
of soda and sesquioxide of manganese, as described under the head of
baryta, a bead of a brown, brownish-green, or dark grey color is
produced. Carbonate of soda does not dissolve pure strontia. The
carbonate and sulphate of strontia melt with soda upon platinum foil
to a bead, which is milk-white when cold, but fused upon charcoal they
are absorbed. Strontia or its compounds produce with borax, or
microcosmic salt, the same reactions as baryta. When they are
moistened with nitrate of cobalt, and ignited in the oxidizing flame,
a black, or grey infusible mass is produced.
(_c._) _Lime, Oxide of Calcium _(CaO).--Lime does not occur free in
nature, but in combination with acids, chiefly the carbonic and
sulphuric. The phosphate occurs principally in bones. The hydrate and
the salts of lime are in their properties similar to those of the two
preceding alkaline earths. In the pure state, the oxide of calcium is
white; it slakes, produces a high temperature, and falls into a white
powder when sprinkled with a little water. It is now a hydrate, and
has greatly increased in volume. The hydrate of lime is far less
soluble in water than either those of baryta or strontia, and is less
soluble in hot water than in cold. Lime, its hydrate and sulphide of
calcium, have a strong alkaline reaction upon red litmus paper. Lime
and its hydrate are infusible, but produce at a strong red heat a very
intense and splendid white light, while the hydrate loses its water.
The carbonate of lime is also infusible, but at a red heat the
carbonic acid is expelled, and the residue becomes caustic, appears
whiter, and produces an intenser light. The sulphate of lime melts
with difficulty, and presents the appearance of an enamelled mass when
cold. By heating it upon charcoal it fuses in the reducing flame, and
is reduced to a sulphide. This has a strong hepatic odor, and exerts
an alkaline reaction upon red litmus paper. By exposing lime, or its
compounds, upon platinum wire--or as a small splinter of the mineral
in the platinum tongs--to the point of the blue flame, a purple color,
similar to that of lithia and strontia, is communicated to the
external flame, but this color is not so intense as that produced by
strontia, and appears mixed with a slight tinge of yellow. This color
is most intense with the chloride of calcium, while the carbonate of
lime produces at first a yellowish color, which becomes red, after the
expulsion of the carbonic acid. Sulphate of lime produces the same
color, but not so intense. Among the silicates of lime only the
tablespar (3CaO, 2SiO^{3}) produces a red color. Fluorspar (CaFl)
produces a red as intense as pure lime, and fuses into a bead.
Phosphate and borate of lime produce a green flame which is only
characteristic of their acids. The presence of baryta communicates a
green color to the flame. The presence of soda produces only a yellow
color in the external flame.
If alcohol is poured over lime or its compounds and inflamed, a red
color is communicated to the flame. The presence of baryta or soda
prevents this reaction. Lime and its compounds do not dissolve much by
fusion with carbonate of soda. If this fusion is effected on charcoal,
the carbonate of soda is absorbed and the lime remains as a
half-globular infusible mass on the charcoal. This is what
distinguishes lime from baryta and strontia, and is a good method of
separating the former from the latter. Lime and its compounds fuse
with borax in the oxidizing and reducing flames to a clear bead, which
remains clear when cold, but when overcharged with an excess or heated
intermittingly, the bead appears, when cold, crystalline and uneven,
and is not so milk-white as the bead of baryta or strontia, produced
under the same circumstances. The carbonate of lime is dissolved with
a peculiar hissing noise. Microcosmic salt dissolves a large quantity
of lime into a clear bead, which is milky when cold. When the bead has
been overcharged with lime, by a less excess, or by an intermittent
flame, we will perceive in the bead, when cold, fine crystals in the
form of needles. Lime and its compounds form by ignition with nitrate
of cobalt, a black or greyish-black infusible mass.
(_d._) _Magnesia_ (MgO).--Magnesia occurs in nature in several
minerals. It exists in considerable quantity combined with carbonic,
sulphuric, phosphoric, and silicic acids, etc. Magnesia and its
hydrate are white and very voluminous, scarcely soluble in hot or cold
water, and restores moistened red litmus paper to its original blue
color. Magnesia and its hydrate are infusible, the latter losing its
water by ignition. The carbonate of magnesia is infusible, loses its
carbonic acid at a red heat, and shrinks a little. It now exerts upon
red litmus paper an alkaline reaction. The sulphate of magnesia, at a
red heat, loses its water and sulphuric acid, is entirely infusible,
and gives now an alkaline reaction. The artificial Astrachanit (NaO,
SO^{3} + MgO, SO^{3} + 4HO) fuses easily. When fused on charcoal, the
greater part of the sulphate of soda is absorbed, and there remains an
infusible mass.
Magnesia and its compounds do not produce any color in the external
flame, when heated in the point of the blue flame. The most of the
magnesia minerals yield some water when heated in a glass tube closed
at one end.
Magnesia, in the pure state, or as the hydrate, does not fuse with
soda. Some of its compounds are infusible likewise with soda, and
swell up slightly, while others of them melt with soda to a slightly
opaque mass. Some few (such as the borate of magnesia) give a clear
bead with soda, though it becomes slightly turbid by cooling when
saturated with magnesia, and crystallizes in large facets.
Magnesia and its compounds give beads with borax and microcosmic salt
similar to those of lime. By igniting magnesia or its compounds very
strongly in the oxidizing flame, moistening with nitrate of cobalt,
and re-igniting in the oxidation flame, they present, after a
continued blowing, a pale flesh-color, which is more visible when
cold. It is indispensable that the magnesia compounds should be
completely white and free of colored substances, or the color referred
to cannot be discerned. In general the reactions of magnesia before
the blowpipe are not sufficient, and it will be necessary to confirm
its presence or absence by aid of reagents applied in the wet way.
THIRD GROUP.--THE EARTHS, ALUMINA, GLUCINA, YTTRIA, THORINA, AND
ZIRCONIA.
The substances of this group are distinguished from the preceding by
their insolubility in water, in their pure or hydrated state--that
they have no alkaline reaction upon litmus paper, nor form salts with
carbonic acid. The earths are not volatile, and, in the pure state,
are infusible. They cannot be reduced to the metallic state before the
blowpipe. The organic salts are destroyed by ignition, while the
earths are left in the pure state, mixed with charcoal, from the
organic acids. The most of their neutral salts are insoluble in water;
the soluble neutral salts change blue litmus paper to red, and lose
their acids when ignited.
(_a._) _Alumina_ (Al^{2}O^{3}).--This earth is one of our most common
minerals. It occurs free in nature in many minerals, as sapphire,
etc.; or in combination with sulphuric acid, phosphoric acid, and
fluorine, and chiefly silicates. Pure alumina is a white crystalline
powder, or yellowish-white, and amorphous when produced by drying the
hydrate, separated chemically from its salts. Alumina is quite
unalterable in the fire; the hydrate, however, losing its water at a
low red heat. The neutral salts of alumina, with most acids, are
insoluble in water. Those soluble in it have an acid reaction upon
litmus paper, changing the blue into red.
The sulphates of alumina eliminate water when heated in a glass tube
closed at one end. By ignition, sulphurous acid (SO^{2}) is given off,
which can be recognized by its smell, and by its acid reaction upon
blue litmus paper, when a small strip of it moistened is brought
within the orifice of the tube; an infusible residue is left in the
tube.
The greater part of the alumina compounds give off water with heat;
the most of them are also infusible, except a few phosphates and
silicates.
Pure alumina does not fuse with carbonate of soda. The sulphates, when
exposed upon charcoal with soda to the reducing flame, leave a hepatic
residue. The phosphates melt with a little soda, with a hissing noise,
to a semi-transparent mass, but they are infusible with the addition
of soda, and give only a tough mass. This is the case, likewise, with
the silicates of alumina. Fluoride of aluminium melts with carbonate
of soda to a clear bead, spreads by cooling, and appears then
milk-white. Borax dissolves the alumina compounds slowly in the
oxidizing and reducing flames to a clear bead, which is also clear
when cold, or heated intermittingly with a vacillating flame. The bead
is turbid, as well in the heat as the cold, when an excess of alumina
is present. When the alumina compound is added to excess in the
powdered form, the bead appears crystalline upon cooling, and melts
again with great difficulty.
Alumina and its compounds are slowly dissolved in the microcosmic salt
to a bead, clear in both flames, and when hot or cold. When alumina is
added to excess, the undissolved portion appears semi-transparent.
Alumina melts with bisulphate of potash into a mass soluble in water.
When the powdered alumina compounds are strongly ignited in the
oxidizing flame, then moistened with nitrate of cobalt, and re-ignited
in the oxidizing flame, an infusible mass is left, which appears, when
cooled, of an intense blue color. The presence of colored metallic
oxides, in considerable quantity, will alter or suppress this
reaction. The silicates of the alkalies produce, in a very strong
heat, or continued heat, with nitrate of cobalt, a pale blue color.
The blue color produced by alumina is only distinctly visible by
daylight; by candle-light it appears of a dirty violet color.
(_b._) _Glucina._ (G^{2}O^{3}).--Glucina only occurs in a few rare
minerals, in combination with silica and alumina. It is white and
insoluble in the pure state, and its properties generally are similar
to those of alumina. The most of its compounds are infusible, and
yield water by distillation. Carbonate of soda does not dissolve
glucina by ignition. Silicate of glucina melts with carbonate of soda
to a colorless globule. Borax and microcosmic salt dissolve glucina
and its compounds to a colorless bead which, when overcharged with
glucina, or heated with the intermittent flame appears, after cooling,
turbid or milk-white. Glucina yields, by ignition with nitrate of
cobalt, a black, or dark grey infusible mass.
(_c._) _Yttria_ (YO) occurs only in a few rare minerals, and usually
in company with terbium and erbium. Its reactions before the blowpipe
are similar to the preceding, but for its detection in compounds it
will be necessary to resort to analysis in the wet way.
(_d._) _Zirconia_ (Zr^{2}O^{3}).--This substance resembles alumina in
appearance, though it occurs only in a few rare minerals. It is in the
pure state infusible, and at a red heat produces such a splendid and
vivid white light that the eyes can scarcely endure it. Its other
reactions before the blowpipe are analogous to glucina. Microcosmic
salt does not dissolve so much zirconia as glucina, and is more prone
to give a turbid bead. Zirconia yields with nitrate of cobalt, when
ignited, an infusible black mass. To recognize zirconia in compounds
we must resort to fluid analysis.
(_e._) _Thorina_ (ThO).--This is the rarest among the rare minerals.
In the pure state it is white and infusible, and will not melt with
the carbonate of soda. Borax dissolves thorina slowly to a colorless,
transparent bead, which will remain so when heated with the
intermittent flame. If overcharged with the thorina, the bead
presents, on cooling, a milky hue. Microcosmic salt dissolves the
thorina very tardily. By ignition with nitrate of cobalt, thorina is
converted into an infusible black mass,
CLASS II.
FOURTH GROUP. CERIUM, LANTHANIUM, DIDYMIUM, COLUMBIUM, NIOBIUM,
PELOPIUM, TITANIUM, URANIUM, VANADIUM, CHROMIUM, MANGANESE.
The substances of this group cannot be reduced to the metallic state,
neither by heating them _per se_, nor by fusing them with reagents.
They give by fusion with borax or microcosmic salt, colored beads,
while the preceding groups give colorless beads.
(_a._) _Cerium_ (Ce).--This metal occurs in the oxidated state in a
few rare minerals, and is associated with lanthanium and didymium,
combined with fluorine, phosphoric acid, carbonic acid, silica, etc.
When reduced artificially, it forms a grey metallic powder.
(_a._) _Protoxide of Cerium_ (CeO).--It exists in the pure state as
the hydrate, and is of a white color. It soon oxidizes and becomes
yellow, when placed in contact with the air. When heated in the
oxidation flame, it is converted into the sesquioxide, and then is
changed into light brick-red color. In the oxidation flame it is
dissolved by borax into a clear bead, which appears of an orange or
red while hot, but becomes yellow upon cooling. When highly saturated
with the metal, or when heated with a fluctuating flame, the bead
appears enamelled as when cold. In the reduction flame it is dissolved
by borax to a clear yellow bead, which is colorless when cold. If too
much of the metal exists in the bead, it then appears enamelled when
cooled.
Microcosmic salt dissolves it, in the oxidation flame, to a clear
bead, which is colored dark yellow or orange, but loses its color when
cold. In the reduction flame the bead is colorless when either hot or
cold. Even if highly saturated with the metal, the bead remains
colorless when cold. By fusing it with carbonate of soda upon charcoal
in the reduction flame, the soda is absorbed by the charcoal, while
the protoxide of the metal remains as a light grey powder.
(_B._) _Sesquioxide of Cerium_ (Ce^{2}O^{3}).--This oxide, in the pure
state, is a red powder. When heated with hydrochloric acid, it
produces chlorine gas, and is dissolved to a salt of the protoxide. It
is not affected by either the flame of oxidation or of reduction; when
fused with borax or microcosmic salt, it acts like the protoxide. It
does not fuse with soda upon charcoal. In the reduction flame it is
reduced to the protoxide, which remains of a light grey color, while
the soda is absorbed by the charcoal.
(_b._) _Lanthanium_ (La.)--This metal is invariably associated with
cerium. It presents, in its metallic state, a dark grey powder, which
by compression acquires the metallic lustre.
The _oxide of lanthanium_ (LaO) is white, and its salts are colorless.
Heated upon charcoal, it does not change either in the oxidation flame
or that of reduction. With borax, in the flame of oxidation or
reduction, it gives a clear colorless bead. This bead, if saturated,
and when hot, presents a yellow appearance, but is clouded or
enamelled when cold. With microcosmic salt the same appearance is
indicated. It does not fuse with carbonate of soda, but the soda is
absorbed by the charcoal, while the oxide remains of a grey color.
(_c._) _Didymium_ (D).--This metal occurs only in combination with the
preceding ones, and it is therefore, like them, a rare one.
_Oxide of Didymium_ (DO).--This oxide is of a brown color, while its
salts present a reddish-violet or amethyst color. The oxide is
infusible in the oxidation flame, and in that of reduction it loses
its brown color and changes to grey. With borax in the oxidation
flame, it fuses to a clear dark red or violet bead, which retains its
clearness when highly saturated with the oxide, or if heated with a
fluctuating flame.
The reactions with microcosmic salt are the same as with borax.
It does not melt with carbonate of soda upon charcoal, but the oxide
remains with a grey color, while the soda is absorbed by the charcoal.
(_d._) _Columbium,_ (_Tantalum_--Ta).--This rare metal occurs quite
sparingly in the minerals _tantalite_, _yttrotantalite_, etc., as
columbic acid. In the metallic state, it presents the appearance of a
black powder, which, when compressed, exhibits the metallic lustre.
When heated in the air it is oxidized into columbic acid, and is only
soluble in hydrofluoric acid, yielding hydrogen. It is oxidized by
fusion with carbonate of soda or potash.
_Columbic Acid_ (Ta^{2}O^{3}) is a white powder, and is infusible.
When heated in the flame of oxidation or reduction, it appears of a
light yellow while hot, but becomes colorless when cold. With borax,
in the flames of oxidation and reduction, it fuses to a clear bead,
which appears by a certain degree of saturation, of a yellow color so
long as it continues hot, but becomes colorless when cold. If
overcharged, or heated with an intermittent flame, it presents an
enamel white when cool.
It melts with microcosmic salt quite readily in both of the flames, to
a clear bead, which appears, if a considerable quantity of columbic
acid be present, of a yellow color while hot, but colorless when cold,
and does not become clouded if the intermittent flame be applied to
it.
With carbonate of soda it fuses with effervescence to a bead which
spreads over the charcoal. Melted with more soda, it becomes absorbed
by the charcoal.
It yields, moistened with a solution of nitrate of cobalt, and exposed
to the oxidation flame after continued blowing, an infusible mass,
presenting while hot a light grey color, but after being cooled that
of a light red, similar to the color presented by magnesia under the
same circumstances. But if there be some alkali mixed with it, a
fusion at the edges will be manifest, and it will yield by cooling a
bluish-black mass.
(_e._) _Niobium_ (Ni).--This metal occurs as niobic acid in columbite
(tantalite). Niobic acid is in its properties similar to columbic
acid. It is white and infusible. By heating it either in the flames of
reduction or oxidation, it presents as long as it continues hot, a
greenish-yellow color, but becomes white when cool. Borax dissolves it
in the oxidation flame quite readily to a clear bead, which, with a
considerable quantity of niobic acid, is yellow when hot, but
transparent and colorless when cold. A saturated bead is clear when
either hot or cold, but becomes opaque when heated intermittingly.
In the flame of reduction, borax is capable of dissolving more of the
niobic acid, so that a bead overcharged and opaque in the oxidation
flame appears quite clear when heated in the flame of reduction. A
bead overcharged in the flame of reduction, appears by cooling dim and
bluish-grey.
Microcosmic salt dissolves in the flame of oxidation a great quantity
of it to a clear bead, which is yellow while hot, but colorless when
cold.
In the flame of reduction, and in presence of a considerable quantity
of niobic acid, the bead appears while hot of a light dirty blue
color, and when cold, of a violet hue; but by the addition of more
niobic acid, the bead, when hot, is of a dirty dark blue color, and
when cold, of a transparent blue. In the presence of the oxides of
iron, the bead is, while hot, of a brownish-red color, but changing
when cool to a dark yellow.
This acid fuses with an equal quantity of carbonate of soda upon
charcoal, to a bead which spreads very quickly, and is then infusible.
When fused with still more soda, it is absorbed.
When moistened with nitrate of cobalt, and heated in the flame of
oxidation, it yields an infusible mass which appears grey when hot,
and dirty green when cold; but if the heat has been too strong, it is
fused a little at the edges, which present a dark bluish-grey color.
_Pelopium_ (Pe).--This metal occurs as an acid in the mineral
columbite (tantalite), and is very similar to the two preceding
metals.
(_f._) _Pelopic Acid_ (PeO^{3}).--This acid is white, and appears
yellow when heated, but resumes its white color when cold. Borax
dissolves it in the oxidation flame to a clear colorless bead, which
appears, when overcharged and heated intermittingly, enamel-white when
cold. This is likewise the case in the flame of reduction, but when
overcharged the color is light grey, when the bead is cooled.
Microcosmic salt dissolves it in the flame of oxidation, to a clear
yellow bead, which loses its color when cold. In the reduction flame,
when the bead is highly saturated, a violet-brown color is produced.
In presence of the oxides of iron, the reactions are like those of
niobic acid. With carbonate of soda, the reactions are similar to
those of niobic acid. By heating with nitrate of cobalt, it yields a
light grey infusible mass.
(_g._) _Titanium_ (Ti).--This metal occurs occasionally in the slags
of iron works, in the metallic state, as small cubical crystals of a
red color. It is a very hard metal, and very infusible. Titanic acid
occurs in nature crystallized in _anatase_, _arkansite_, _brookite_,
and _rutile_. Titanium is harder than agate, entirely infusible, and
loses only a little of its lustre, which can be regained by fusion
with borax. It does not melt with carbonate of soda, borax, or
microcosmic salt, and is insoluble in every acid except the
hydrofluoric. By ignition with saltpetre it is converted into titanic
acid, which combines with the potassium, forming the titanate of
potassium.
_Titanic Acid_ (TiO^{2}) is white, insoluble, and, when heated, it
appears yellow while hot, but resumes upon cooling its white color.
Borax dissolves it in the oxidation flame to a clear yellow bead,
which when cool is colorless. When overcharged, or heated with the
intermitting flame, it is enamel-white after being cooled. In the
reduction flame, the bead appears yellow, if the acid exists in small
quantity, but if more be added, then it is of an orange, or dark
yellow, or even brown. The saturated bead, when heated intermittingly,
appears when cold of an enamelled blue. By addition of the acid, and
by heating the bead on charcoal in the reduction flame, it becomes
dark yellow while hot, but dark blue, or black and opaque when cold.
This bead appears, when heated intermittingly, of a light blue, and
when cold, enamelled.
Microcosmic salt fuses with it in the oxidation flame to a clear
colorless bead, which appears yellow only in the presence of a
quantity of titanic acid, though by cooling it loses its color. In the
reduction flame this bead exhibits a yellow color when hot, but is red
while cooling, and when cold of a beautiful bluish-violet. If the bead
is overcharged, the color becomes so dark that the bead appears
opaque, though not presenting an enamel appearance. By heating the
bead again in the oxidation flame the color disappears. The addition
of some tin promotes the reduction. If the titanic acid contains oxide
of iron, or if some is added, the bead appears, when cold,
brownish-yellow, or brownish-red.
By fusion with carbonate of soda, titanic acid is dissolved with
effervescence to a clear dark yellow bead, which crystallizes by
cooling, whereby so much heat is eliminated, that the bead, at the
instant of its crystallization, glows with great brightness. A
reduction to a metal cannot, however, be effected. By ignition with a
solution of nitrate of cobalt in the oxidation flame, it yields an
infusible yellowish-green mass.
(_h._) _Uranium_ (U).--This rare metal occurs in the form of protoxide
along with other oxides, in the mineral _pitch-blende_; as peroxide in
_uranite_ and _uran-mica_, associated with phosphoric acid and lime.
In the metallic state it presents the appearance of a dark grey mass,
which is infusible, and remains unchanged when under water, or when
exposed to dry air, but, when heated in the oxidation flame, it
becomes oxidized, with lively sparkling, to a dark green mass,
composed of the protoxide and peroxide.
The _protoxide of uranium_ (UO) is black, uncrystalline, or forms a
brown powder. When exposed to heat it is converted partially into
peroxide, when it has a dark green color.
The _peroxide of uranium_ (U^{2}O^{3}) is of an orange color, while
its hydrate is of a fine yellow color, and in the form of a powder.
The salts are yellow.
By heating it in the oxidation flame, it acquires a dark green color,
and is partly reduced to protoxide. In the reduction flame it presents
a black appearance, and is there completely reduced to protoxide.
Borax dissolves it in the oxidation flame to a clear dark yellow bead,
which is colorless when cold, if the metal is not present in great
quantity. If more of the metal, or peroxide, be added, the bead
changes to orange when hot, and light yellow when cold. When heated
with the intermittent flame, it requires a large quantity of the
peroxide to produce an enamel appearance in the cooled bead.
In the flame of reduction the bead becomes of a dirty green color,
being partly reduced to protoxide, and appears, with a certain degree
of saturation, black, when heated intermittingly, but never enamelled.
The bead appears on charcoal, and with the addition of tin, of a dark
green color.
It fuses with microcosmic salt in the oxidation flame to a clear
yellow bead, which is greenish-yellow when cold. In the reduction
flame it produces a beautiful green bead, which increases when cold.
When fused upon charcoal with the addition of tin, its color is
darker. Carbonate of soda does not dissolve it, although with a very
small portion of soda it gives indications of fusion, but with still
more of the soda it forms a yellow, or light-brown mass, which is
absorbed by the charcoal, but it is not reduced to the metallic state.
(_i._) _Vanadium_ (V).--This very rare mineral is found in small
quantity in iron-ores, in Sweden, and as vanadic acid in a few rare
minerals. The metal presents the appearance of an iron-grey powder,
and sometimes that of a silver-white mass. It is not oxidized either
by air or water, and is infusible.
_Vanadic Acid_ (VO^{3}) fuses upon platinum foil to a deep orange
liquid, which becomes crystalline after cooling. When fused upon
charcoal, one part of it is absorbed, while the rest remains upon the
charcoal and is reduced to protoxide similar in appearance to
graphite.
A small portion of it fuses with borax in the oxidation flame to a
clear colorless bead, which appears, with the addition of more vanadic
acid, of a yellow color, but changes to green when cold.
In the reduction flame the bead is brown while hot, but changes, upon
cooling, to a beautiful sapphire-green. At the moment of
crystallization, and at a degree of heat by which at daylight no
glowing of the heated mass is visible it begins to glow again. The
glow spreads from the periphery to the centre of the mass, and is
caused by the heat liberated by the sudden crystallization of the
mass. It now exhibits an orange color, and is composed of needle
crystals in a compact mass.
Microcosmic salt and vanadic acid fuse in the oxidation flame to a
dark yellow bead which, upon cooling, loses much of its color.
In the reduction flame the bead is brown while hot, but, upon cooling,
acquires a beautiful green color.
Vanadic acid fuses with carbonate of soda upon charcoal, and is
absorbed.
(_k._) _Chromium_ (Cr) occurs in the metallic state only in a very
small quantity in meteoric iron, but is frequently found in union with
oxygen, as oxide in chrome iron ore, and as chromic acid in some lead
ores.
In the metallic state it is of a light grey color, with but little
metallic lustre, very hard, and not very fusible. Acids do not act
upon it, except the hydrofluoric; fused with nitre, it forms chromate
of potassa. It is unaltered in the blowpipe flame.
_Sesquioxide of Chromium_ (Cr^{2}O^{3}).--This oxide forms black
crystals of great hardness, and is sometimes seen as a green powder.
Its hydrate (Cr^{2}O^{3} + 6HO) is of a bluish-grey color. It forms
with acids two classes of isomeric salts, some of which are of a
green color, and the others violet-red or amethyst. The neutral and
soluble salts have an acid reaction upon blue litmus paper, and are
decomposed by ignition.
Sesquioxide of chromium in the oxidation and reduction flames is
unchangable. When exposed to heat, the hydrate loses its water, and
gives a peculiarly beautiful flame. In the oxidation flame borax
dissolves the sesquioxide of chromium slowly to a yellow bead (chromic
acid) which is yellowish green when cold. Upon the addition of more of
the oxide, the bead is dark red while hot, but changes to green as it
becomes cold.
In the reduction flame the bead is of a beautiful green color, both
while hot and when cold. It is here distinguished from vanadic acid,
which gives a brownish or yellow bead while hot.
With microcosmic salt it fuses in the oxidation flame to a clear
yellow bead, which appears, as it cools, of a dirty-green, color, but
upon being cool is of a fine green color. If there be a superabundance
of the oxide, so that the microcosmic salt cannot dissolve it, the
bead swells up, and is converted into a foamy mass, in consequence of
the development of gases.
In the reduction flame it fuses to a fine green bead. The addition of
a little tin renders the green still deeper.
Sesquioxide of chromium fuses with carbonate of soda upon platinum
foil to a brown or yellow bead, which, upon cooling, appears of a
lighter color and transparent (chromate of sodium).
When fused with soda upon charcoal, the soda is absorbed, and the
green oxide is left upon it, but is never reduced to the metallic
state.
_Chromic Acid_ (CrO^{3}) crystallizes in the form of deep ruby red
needles. It is decomposed into sesquioxide and oxygen when heated.
This decomposition is attended with a very lively emission of light,
but this is not the case if the chromic acid has been attained by the
coöperation of an aqueous solution, unless the reduction is effected
in the vapor of ammonia. Before the blowpipe chromic acid produces the
same reactions as the sesquioxide.
(_l._) _Manganese_ (Mn).--This metal occurs in considerable abundance,
principally as oxides, less frequently as salts, and sometimes in
combination with sulphur and arsenic. It is found in plants, and
passes with them into the animal body. In the metallic state, it is
found frequently in cast iron and steel. It is a hard, brittle metal,
fusible with difficulty, and of a light grey color. It tarnishes upon
exposure to the air and under water, and falls into a powder.
_Protoxide of Manganese_ exists as a green powder; as hydrate
separated by caustic alkalies, it is white, but oxidizes very speedily
upon exposure to the air. The protoxide is the base of the salts of
manganese. These salts, which are soluble in water, are decomposed
when heated in the presence of the air--except the sulphate (MnO,
SO^{3}), but if the latter is exposed to ignition for awhile, it then
ceases to be soluble in water, or at least only sparingly so.
_Sesquioxide of Manganese_ (Mn^{2}O^{3}) Occurs very sparingly in
nature as small black crystals (_Braunite_) which give, when ground, a
brown powder. When prepared by chemical process, it is in the form of
a black powder. The hydrate occurs sometimes in nature as black
crystals (_manganite_). By digestion with acids, it is dissolved into
salts of the protoxide. With hydrochloric acid, it yields chlorine.
The _prot-sesquioxide of manganese_ (MnO + Mn^{2}O^{3}) occurs
sometimes in black _crystals_ (_hausmannite_). Prepared artificially,
it is in the form of a brown powder.
_Peroxide of Manganese_ (MnO^{2}) occurs in considerable abundance as
a soft black amorphous mass, or crystallized as pyrolusite, also
reniform and fibrous. It is deprived of a part of its oxygen when
exposed to ignition. It eliminates a considerable quantity of chlorine
from hydrochloric acid, and is thereby converted into chloride of
manganese (ClMn).
Most of the manganese compounds which occur in nature yield water when
heated in a glass tube closed at one end. The sesquioxide and peroxide
give out oxygen when strongly heated, which can be readily detected by
the increased glow which it causes, if a piece of lighted wood or
paper is brought to the mouth of the tube. The residue left in the
tube is a brown mass (MnO + Mn^{2}O^{3}).
When exposed to ignition with free access of air, all manganese oxides
are converted into (MnO + Mn^{2}O^{3}), but without fusion. Such, at
least, is the statement of some of the German chemists, although it
will admit perhaps of further investigation.
Manganese oxides fuse with borax in the oxidation flame to a clear and
intensely colored bead, of a violet hue while hot, but changing to red
as it cools. If a considerable quantity of the oxide is added, the
bead acquires a color so dark as to become opaque. If such be the
case, we have to press it flat, by which its proper color will become
manifest.
In the reduction flame the bead is colorless. A very dark colored bead
must be fused upon charcoal with the addition of some tin. The bead
must be cooled very suddenly, for if it cools too slowly, it then has
time to oxidize again. This may be effected by pushing it off the
platinum wire, or the charcoal, and pressing it flat with the forceps.
The oxides of manganese fuse with microcosmic salt in the oxidation
flame, to a clear brownish-violet bead, which appears reddish-violet
while cooling. This bead does not become opaque when overcharged with
manganese. As long as it is kept in fusion a continued boiling or
effervescence takes place, produced by the expulsion of oxygen, in
consequence of the fact that the microcosmic salt cannot dissolve much
sesquioxide, while the rest is reduced to protoxide, is re-oxidated,
and instantly again reduced. If the manganese is present in such a
minute quantity as not to perceptibly tinge the bead, the color may be
made to appear by the contact of a crystal of nitre while hot. The
bead foams up upon the addition of the nitre, and the foam appears,
after cooling, of a rose-red or violet color. In the reduction flame
the bead sometimes becomes colorless.
The oxides of manganese fuse with carbonate of soda upon platinum
foil or wire, to a clear green bead, which appears bluish-green and
partially opaque when cold (manganate of soda NaO + MnO^{3}). A very
minute trace of manganese will produce this green color. The oxides of
manganese cannot be reduced upon charcoal with carbonate of soda
before the blowpipe. The soda is absorbed, and (MnO + Mn^{2}O^{3}) is
left.
GROUP FIFTH.--IRON, COBALT, NICKEL.
The oxides of this group are reduced to the metallic state when fused
with carbonate of soda upon charcoal in the reduction flame. Metals
when thus reduced form powders, are not fusible or volatile in the
blowpipe flame, but they are attracted by the magnet.
Furthermore, these oxides are not dissolved by carbonate of soda in
the oxidation flame, but they produce colored beads with borax and
microcosmic salt.
(_a._) _Iron._--It occurs in great abundance in nature. It is found in
several places in America in the metallic state, and it likewise
occurs in the same state in meteors. It occurs chiefly as the oxide
(red hematite, brown hematite, magnetic oxide, etc.), and frequently
in combination with sulphur. Iron also forms a constituent of the
blood.
Metallic iron is of a grey color, and presents the metallic lustre
vividly when polished. It is very ductile, malleable, and tenacious.
It is very hard at common temperatures, but soft and yielding at a red
heat.
In dry and cold air, iron does not oxidize, but when the air is dry
and moist, it oxidizes rapidly. This likewise takes place with great
rapidity when the metal is heated to redness. When submitted to a
white heat iron burns with brilliant scintillations.
_Protoxide of Iron_ (FeO).--This oxide does not occur pure in nature,
but in union with the peroxide of iron and other substances. It
presents the form of a black powder, and has some metallic lustre, is
brittle, and fuses at a high temperature to a vitreous looking mass.
It is attracted by the magnet, and of course is susceptible of
becoming magnetic itself. It forms with water a hydrate, but this
passes so rapidly into a state of higher oxidation, that it is
difficult to keep it in the pure state.
_Magnetic Oxide of Iron_ (FeO + Fe^{2}O^{3}).--This peculiar oxide is
of a dark color, and is magnetic, so that tacks or small nails adhere
to it when brought in contact with it. It is the variety of the oxide
termed "loadstone." It is found frequently crystallized in octahedrons
in Scandinavia and other places. Magnetic oxide of iron is produced
when red-hot iron is hammered.
_Sesquioxide of Iron_ (Fe^{2}O^{3}).--This oxide is found native in
great abundance as red hematite and specular iron, crystallized in the
rhombic form. In the crystalline state it is of a blackish-grey color,
and possessed of the metallic lustre. When powdered, it forms a
brownish-red mass. When artificially prepared, it presents the
appearance of a blood-red powder. It is not magnetic, and has less
affinity for acids than the protoxide. Its hydrate is found native as
brown hematite.
By exposing the peroxide of iron to the oxidation flame, it is not
acted upon, but in the reduction flame it becomes reduced to the
magnetic oxide.
The oxides of iron are dissolved by borax in the oxidation flame to a
clear dark-yellow or dark-red bead, which appears lighter while
cooling, and yellowish when cold. In the presence of a very small
quantity of iron, the bead appears colorless when cold. If the iron is
increased, the bead is opaque while cooling, and of a dirty
dark-yellow color when cold. In the reduction flame, and fused upon
platinum wire, the bead appears dark green (FeO + Fe^{2}O^{3}). By the
addition of some tin, and fused upon charcoal, the bead appears
bluish-green, or not unlike that of sulphate of iron.
Microcosmic salt dissolves the oxides of iron in the oxidation flame
to a clear bead, which, by the addition of a considerable quantity of
iron, becomes of an orange color while hot, but gets lighter while
cooling, presenting finally a greenish hue, and gradually becoming
lighter, till, when cold, it is colorless. If the iron is increased,
the hot bead presents a dark red color, but while cooling a
brownish-red, which changes to a dirty-green, and, when cold, to a
brownish-red color. The decrease of the color during the transition
from the hot to the cold state is still greater in the bead formed by
the microcosmic salt.
In the reduction flame no change is visible if the quantity of iron be
small. By the addition of more iron, the hot bead appears red, and
while cooling, changes to yellow, then green, and, when cold, is of a
dull red. By fusing the bead on charcoal with a small addition of tin,
it exhibits, while cooling, a bluish-green color, but, when cold, is
colorless.
The oxides of iron are not dissolved in the oxidation flame by fusion
with carbonate of soda. By ignition with soda upon charcoal in the
reduction flame, they are absorbed and reduced to the metallic state.
Cut out this portion of the charcoal; grind it with the addition of
some water in an agate mortar, for the purpose of washing off the
carbon particles, when the iron will remain as a grey magnetic powder.
(_b._) _Cobalt_ (Co) occurs in combination with arsenic and sulphur,
and associated with nickel and iron. It is found occasionally in
combination with selenium, and there are a traces of it in meteoric
iron. In the metallic state it is of a light, reddish-grey color,
rather brittle, and only fusible at a strong white heat; at common
temperatures it is unalterable by air or water. At a red heat, it
oxidizes slowly and decomposes water; at a white heat it burns with a
red flame. Cobalt is soluble in dilute sulphuric or hydrochloric acid
by the aid of heat, whereby hydrogen is eliminated. These solutions
have a fine red color.
_Protoxide of Cobalt_ (CoO).--It is an olive-green powder, but, by
exposure to the air, it becomes gradually brown. Its hydrate is a rich
red powder. The solution of its salts is red, but the aqueous solution
is often blue.
When heated in the oxidation flame, the protoxide is converted into
the black proto-sesquioxide (CoO + Co^{2}O^{3}). In the reduction
flame it shrinks and is reduced without fusion to the metallic state.
It is now attracted by the magnet and acquires lustre by compression.
Borax dissolves it in the oxidation flame, and produces a clear,
intensely colored blue bead, which remains transparent and of the same
beautiful blue when cold. This blue is likewise manifest even if the
bead be heated intermittingly. If the cobalt exists in considerable
quantity, the color of the bead is so intense as to appear almost
black.
This reaction of cobalt is so characteristic and sensitive that it can
detect a minute trace.
With microcosmic salt the same reaction is exhibited, but not so
sensitive, nor is the bead so intensely colored when cold as that with
borax.
By fusion with carbonate of soda upon a platinum wire, with a very
small portion of cobalt, a bright red colored mass is produced which
appears grey, or slightly green when cold. By fusion upon platinum
foil the fused portion floats down from the sides, and the foil is
coated around the undissolved part, with a thin, dark-red sublimate.
When fused upon charcoal, and in the reduction flame, it is reduced
with soda to a grey powder, which is attracted by the magnet, and
exhibits the metallic lustre by compression.
_Sesquioxide of Cobalt_ (Co^{2}O^{3}).--It is a dark brown powder. Its
hydrate (2HO + Co^{2}O^{3}) is a brown powder. It is soluble only in
acetic acid as the acetate of the sesquioxide. All other acids
dissolve its salts to protoxide, the hydrochloric acid producing
chloric gas. By ignition in the oxidation flame, it is converted into
the proto-sesquioxide (CoO + Co^{2}O^{3}) and produces with reagents
before the blowpipe the same reactions as the protoxide.
(_c._) _Nickel_ (Ni).--This metal occurs invariably associated with
cobalt, and in analogous combinations, chiefly as the arsenical
nickel. In the metallic state it is greyish, silver-white, has a high
lustre, is hard, and malleable both cold and hot. At common
temperatures, it is unalterable either in dry or moist air. When
ignited, it tarnishes. It is easily dissolved by nitric acid, but very
slowly by dilute sulphuric or hydrochloric acid, producing hydrogen.
_Protoxide of Nickel _(NiO).--It is in the form of small greyish-black
octahedrons, or a dark, greenish-grey powder. Its hydrate is a green
powder. Both are unalterable in the air, and are soluble in nitric,
sulphuric, and hydrochloric acids, to a green liquid. The protoxide is
the base of the salts of nickel, which in the anhydrous state are
yellow, and when hydrated are green. The soluble neutral salts change
blue litmus paper to red. By ignition in the oxidation flame,
protoxide of nickel is unaltered. In the reduction flame and upon
charcoal, it becomes reduced, and forms a grey adherent powder, which
is infusible, and presents the metallic lustre by compression, and is
magnetic. Borax dissolves it in the oxidation flame very readily to a
clear bead, of a reddish-violet or dark yellow color, but yellow or
light red when cold. If there is but a small quantity of the oxide
present, it is colorless. If more of the oxide be present, the bead is
opaque and dark brown, and appears, while cooling, transparent and
dark red. By the addition of a salt of potassa (the nitrate or
carbonate) a blue or a dark purple colored bead is produced. The borax
bead, in the reduction flame, is grey, turbid, or completely opaque
from the reduced metallic particles. After a continued blast, the bead
becomes colorless, although the particles are not fused. If the nickel
contains cobalt, it will now be visible with its peculiar blue color.
Upon charcoal, and by the addition of some tin, the reduction of the
oxide of nickel is easily effected, while the reduced nickel fuses
with the tin.
The oxide of nickel is dissolved by microcosmic salt in the oxidation
flame to a clear bead, which appears reddish while hot, but yellow and
sometimes colorless when cooling. If a considerable quantity of nickel
be present the heated bead is of a brown color, but orange when
cooled. In the reduction flame, and upon platinum wire, the color of
the bead is orange when cold; but upon charcoal, and with the addition
of a little tin, the bead appears grey and opaque. After being
submitted to the blowpipe flame all the nickel is reduced, and the
bead becomes colorless.
Carbonate of soda does not affect it in the oxidation flame, but in
the reduction flame and upon charcoal, it is absorbed and reduced, and
remains, after washing off the carbon, as a white metallic powder,
which is infusible, and has a greater attraction for the magnet than
iron.
_Sesquioxide of Nickel_ (Ni^{2}O^{3}).--It is in the form of a black
powder, and does not combine with other substances, unless it is
reduced to the protoxide. It exhibits before the blowpipe the same
behavior as the protoxide.
GROUP SIXTH.--ZINC, CADMIUM, ANTIMONY, TELLURIUM.
The substances of this group can be reduced upon charcoal by fusion
with carbonate of soda, but the reduced metals are volatilized, and
cover the charcoal with sublimates.
(_a._) _Zinc_ (Zn).--This metal is found in considerable abundance,
but never occurs in the pure metallic state, but in combination with
other substances, chiefly as sulphide in zinc blende, as carbonate in
calamine, and as the silicate in the kieselzinc ore; also, with
sulphuric acid, the "vitriol of zinc."
Zinc is of a bluish-white color and metallic lustre, is crystalline
and brittle when heated 400°F., but malleable and ductile between 200°
and 300°. It will not oxidize in dry air, but tarnishes if exposed to
air containing moisture, first becomes grey, and then passes into the
white carbonate. It decomposes in water at a glowing heat. It is
dissolved by diluted acids, while hydrogen is eliminated. It melts at
about 775°, and distills when exposed to a white heat in a close
vessel. When heated over 1000° in the open air, it takes fire, and
burns with a bluish-white light, and with a thick white smoke of oxide
of zinc.
_Oxide of Zinc_ (ZnO).--In the pure state, oxide of zinc is a white
powder, infusible, and not volatile. It is readily soluble in acids
after being heated strongly. Its soluble neutral salts, when dissolved
in water, change blue litmus paper to red. Its salts, with organic
acids, are decomposed by ignition, and the carbonate of zinc remains.
The oxide of zinc turns yellow by being ignited in the oxidation
flame, but it is only visible by daylight; this color changes to white
when cold. It does not melt, but produces a strong light, and it is
not volatile.
It disappears gradually in the flame of reduction, while a white smoke
sublimates upon the charcoal. This sublimate is yellow while hot, but
changes to white when cold. The cause of this is, that the oxide is
reduced, is volatilized, and re-oxidized, by going through the
external flame in the form of a metallic vapor.
Borax dissolves oxide of zinc in the flame of oxidation easily to a
clear bead, which is yellow while hot, and colorless when cold. The
bead becomes, by the addition of more oxide, enamelled, while cooling.
If the bead is heated with the intermittent flame, it is milk-white
when cold. When heated in the flame of reduction upon platinum wire,
the bead at first appears opaque, and of a greyish color, but becomes
clear again after a continued blast.
When heated upon charcoal in the reduction flame, it is reduced to a
metal; but, at the same moment, is volatilized, and sublimes as oxide
of zinc upon the charcoal, about one line's distance from the assay.
This is likewise the case with the microcosmic salt, except that it is
more easily volatilized in the reduction flame.
Carbonate of soda does not dissolve the oxide of zinc in the flame of
oxidation. In the reduction flame and upon charcoal, the oxide of zinc
is reduced to the metallic state, and is volatilized with a white
vapor of the zinc oxide, which sublimes on the charcoal and exhibits a
yellow color while hot, and which changes to white when cold. By a
strong heat the reduced zinc burns with a white flame.
Moistened with a solution of cobalt oxide, and heated strongly in the
flame of oxidation, zinc oxide becomes of a yellowish-green color
while hot, and changes to a beautiful green color when cold.
(_b._) _Cadmium_ (Cd).--This is one of the rare metals. It occurs in
combination with sulphur in _greenockite_, and in some ores of zinc.
It was detected first in the year 1818, and presents itself as a
tin-white metal of great lustre, and susceptible of a fine polish. It
has a fibrous structure, crystallizes easily in regular octahedrons,
presenting often the peculiar arborescent appearance of the fern. It
is soft, but harder and more tenacious than tin; it can be bent,
filed, and easily cut: it imparts to paper a color like that of lead.
It is very malleable and ductile, and can be hammered into thin
leaves. It is easily fused, and melts before it glows (450°). At a
temperature not much over the boiling point of mercury, it begins to
boil, and distills, the vapor of the metal possessing no peculiar
odor. It is unalterable in the air for a long time, but at length it
tarnishes and presents a greyish-white, half metallic color. This
metal easily takes fire when heated in the air, and burns with a
brownish-yellow vapor, while it deposits a yellow sublimate upon
surrounding bodies. It is easily soluble in acids with the escape of
hydrogen, the solutions being colorless. Its salts, soluble in water,
are decomposed by ignition in free air. Its soluble neutral salts
change blue litmus paper to red. The salts, insoluble in water, are
readily dissolved in acids.
_Oxide of Cadmium_ (CdO).--This oxide is of a dark orange color. It
does not melt, and is not volatile, not even at a very high
temperature. Its hydrate is white, loses in the heat its hydratic
water, and absorbs carbonic acid from the air when it is kept in open
vessels.
Cadmium oxide is unaltered when exposed upon platinum wire in the
flame of oxidation. When heated upon charcoal in the flame of
reduction it disappears in a very short time, while the charcoal is
coated with a dark orange or yellow powder, the color of which is more
visible after it is cooled. The portions of this sublimate furthest
from the assay present a visible iridescent appearance. This reaction
of cadmium is so characteristic and sensitive that minerals (for
instance, calamine, carbonate of zinc) which contains from one to five
per cent. of carbonate of cadmium, will give a dark yellowish ring of
cadmium oxide, a little distance from the assay, after being exposed
for a few moments to the flame of reduction. This sublimate is more
visible when cold, and is produced some time previous to the reduction
of the zinc oxide. If a vapor of the latter should appear, it
indicates that it has been exposed too great a length of time to the
flame.
Borax dissolves a considerable quantity of cadmium oxide upon a
platinum wire to a clear yellow bead, which, when cold, is almost
colorless. If the bead is nearly saturated with the cadmium oxide, it
appears milk-white when intermittingly heated. If the bead is
completely saturated, it retains its opalescent appearance. Upon
charcoal, and in the flame of reduction, the bead intumesces, the
cadmium oxide becomes reduced to metal; this becomes volatilized and
re-oxidized, and sublimes upon the charcoal as the yellow cadmium
oxide.
In the oxidation flame, microcosmic salt dissolves a large quantity of
it to a clear bead, which, when highly saturated and while hot, is
yellowish colored, but colorless when cold. By complete saturation,
the bead is enamel-white when cold.
Upon charcoal, in the flame of reduction, the bead is slowly and only
partially reduced, a scanty sublimate being produced on the charcoal.
The addition of tin promotes the reduction.
Carbonate of soda does not dissolve cadmium oxide in the oxidation
flame. In the reduction flame, upon charcoal, it is reduced to metal,
and is volatilized to a red-brown or dark, red sublimate of cadmium
oxide upon the charcoal, at a little distance from the assay the
charcoal presenting the characteristic iridescent appearance. This
reaction is still more sensitive if the cadmium oxide is heated _per
se_ in the reduction flame.
_Antimony_ (Sb).--This metal is found in almost every country. It
principally occurs as the tersulphide (SbS^{3}), either pure or
combined with other sulphides, particularly with basic sulphides.
Sometimes it occurs as the pure metal, and rarer in a state of
oxidation as an antimonious acid and as the oxysulphide.
In the pure state, antimony has a silver-white color, with much
lustre, and presents a crystalline structure. The commercial and
impure metal is of a tin-white color, and may frequently be split in
parallel strata. It is brittle and easily pulverized. It melts at a
low red heat (810°), is volatilized at a white heat, and can be
distilled. At common temperatures it is not affected by the air. At a
glowing heat it takes fire, and burns with a white flame, and with
white fumes, forming volatile antimonious acid. Common acids oxidize
antimony, but dissolve it slightly. It is soluble in aqua regia
(nitro-hydrochloric acid).
_Sesquioxide of Antimony_ (Sb^{2}O^{3}).--In the pure state this oxide
is a white powder, is fusible at a dull red heat to a yellow liquid,
which, after cooling, is greyish-white and crystalline. If it is
heated excluded from the air, it can be volatilized completely; it
sublimes in bright crystals having the form of needles. It occurs
sometimes in nature as white and very bright crystals. It takes fire
when heated in the open air, and burns with a white vapor to
antimonious acid. It fuses with the ter-sulphide of antimony to a red
bead. It is distinguished from the other oxides of antimony by the
readiness with which it is reduced to the metallic state upon
charcoal, and by its easy fusibility and volatility.
The sesquioxide is the base of some salts--for instance, the tartar
emetic. It is not soluble in nitric acid, but is soluble in
hydrochloric acid. This solution becomes milky by the addition of
water. A part of the salts of the sesquioxide of antimony are
decomposed by ignition. The haloid salts are easily volatilized,
without decomposition. Its soluble neutral salts change blue litmus
paper to red, and are converted, by admixture of water, into
insoluble basic and soluble acid salts.
Antimonious acid (antimoniate of sesquioxide of antimony, Sb^{2}O^{3}
+ Sb^{2}O^{5}) is of a white color, but, when heated, of a light
yellow color, but changes to white again when cold. It is infusible
and unaltered by heat. It forms a white hydrate, and both are
insoluble in water and nitric acid. It is partly soluble in
hydrochloric acid, with the application of heat. The addition of water
causes a precipitate in this solution.
_Antimonic Acid _(Sb^{2}O^{5}).--In the pure state this acid is a
light yellow-colored powder. Its hydrate is white, and is insoluble in
water and nitric acid. It is sparingly soluble in hot concentrated
hydrochloric acid. It forms salts with every base, some of which are
insoluble, and others sparingly so. Notwithstanding that antimonic
acid is insoluble in water, it expels the carbonic acid from the
solutions of the carbonates of the alkalies. Antimonic acid and its
hydrate changes moistened blue litmus paper to red.
_Behavior of Antimony and its Oxides before the Blowpipe._
_Metallic Antimony_ fuses easily upon charcoal. When heated to
glowing, and then removed from the flame, it continues to glow for
awhile, and produces a thick white smoke. The vapor crystallizes
gradually, and coats the assay with small crystals which iridesce like
mother of pearl (sesquioxide of antimony). It is not volatile at the
temperature of melted glass. Ignited in an open glass tube, it burns
slowly with a white vapor, which condenses upon the cool part of the
tube, and exhibits some indications of crystallization. This vapor
consists of the sesquioxide, and can be driven by heat from one place
to another, without leaving a residue. If the metallic antimony
contains sulphide of antimony, there is a corresponding portion of
antimonious acid produced, which remains as a white sublimate after
the sesquioxide is removed.
_Sesquioxide of antimony_ melts easily, and sublimes as a white vapor.
It may be prepared by precipitating and drying. When heated, it takes
fire previous to melting, glows like tinder, and is converted into
antimonious acid, which is now infusible. When heated upon charcoal in
the flame of reduction, it is reduced to the metallic state, and
partly volatilized. A white vapor sublimates upon the charcoal, while
the external flame exhibits a greenish-blue color. Antimonious acid is
infusible, produces a strong light, and is diminished in volume when
heated in the external flame, during which time a dense white vapor
sublimes upon the charcoal. It is not, however, in this manner reduced
to the metallic state like the sesquioxide.
_Antimonic acid_, when first heated, becomes white, and is converted
into antimonious acid. Hydrated antimonic acid, which is originally
white, appears at first yellow while giving off water, and then
becomes white again, while oxygen is expelled, and it is converted
into antimonious acid.
The oxides of antimony produce, with blowpipe reagents, the following
reactions: borax dissolves oxides of antimony in the oxidation flame
in considerable quantity to a clear bead, which is yellow while hot,
but colorless when cold. If the bead is saturated, a part of the oxide
is volatilized as a white vapor. Upon charcoal, in the oxidation
flame, it is completely volatilized, and the charcoal is covered with
a white sublimate. Heated upon charcoal in the reducing flame, the
bead is of a greyish color, and partially, if not wholly opaque, from
the presence of reduced metallic particles. A continued heat will
volatilize them, and the bead becomes clear. The addition of tin
promotes the reduction.
Microcosmic salt dissolves the compounds of antimony in the flame of
oxidation with intumescence, to a clear light-yellow colored bead,
which when cold is colorless. Heated upon charcoal in the reduction
flame, the bead is first turbid, but soon becomes transparent. The
addition of tin renders the bead greyish while cooling, but a
continued blast renders it transparent. Soda dissolves the compounds
of antimony upon platinum wire in the oxidation flame, to a clear
colorless bead, which is white when cold.
Upon charcoal, both in the oxidation and reduction flames, the
antimony compounds are readily reduced to the metal, which is
immediately volatilized, and produces a white incrustation of oxide of
antimony upon the charcoal. If the antimony compounds are heated upon
charcoal in the flame of reduction, with a mixture of carbonate of
soda and cyanide of potassium (KCy), there are produced small globules
of metallic antimony. At the same time, a part of the reduced metal is
volatilized (this continues after the assay is removed from the flame)
and re-oxidized. A white incrustation appears upon the charcoal, and
the metallic globules are covered with small white crystals. If this
white sublimate upon the charcoal is moistened with a solution of
cobalt-oxide, and exposed to the reduction flame, a part of it is
volatilized, while the other part passes into higher oxidation, and
remains, after cooling, of a dirty dark-green color.
(_d._) _Tellurium_ (Te).--This is one of the rare metals. It occurs
very seldom in the metallic state, but often with bismuth, lead,
silver, and gold. Tellurium, in the pure state, is silver-white, very
bright, of a foliated or lamellar structure, brittle, and easily
triturated. It is inclined to crystallize. It is soluble in
concentrated sulphuric acid without oxidation. The solution is of a
fine purple color, and gives a precipitate with the addition of water.
_Tellurium in the Metallic form._--By the aid of heat it is oxidized
in sulphuric acid, a portion of the oxygen of the acid oxidizing the
metal, while sulphurous acid gas escapes. This solution is colorless,
and is tellurous acid, dissolved in sulphuric acid. It melts at a low
red heat, and volatilizes at a higher temperature. If tellurium is
heated with free access of air, it takes fire, and burns with a blue
color, the flame being greenish at the edges, while a thick white
vapor escapes, which has a feeble acidulous odor.
_Tellurous Acid_ (TeO^{2}) is of a fine, granulous, crystalline or
white earthy mass, which is partly soluble in water. The solution has
a strong metallic taste, and an acid reaction upon litmus paper.
Heated in a tube closed at one end until it begins to glow, it fuses
to a yellow liquid which is colorless, crystalline, and opaque when
cold. Beads of it remain usually transparent like glass. Heated upon
platinum wire in the flame of oxidation, it melts, and is volatilized
as a white vapor. When heated upon charcoal in the oxidation flame, it
melts, and is reduced to the metallic state, but volatilizes and a
sublimate of white tellurous acid is formed upon the charcoal. The
edge of this deposit is usually red or dark-yellow.
Heated upon charcoal in the flame of reduction, it is rapidly reduced,
the external flame exhibiting a bluish-green color.
Borax dissolves it in the oxidation flame upon platinum wire to a
clear colorless bead which turns grey when heated upon charcoal,
through the presence of reduced metallic particles. Upon charcoal, in
the reduction flame, the bead is grey, caused by the reduced metal.
After a continued blast, tellurium is completely volatilized, and the
bead appears clear again, while a white sublimate is deposited upon
the charcoal.
With microcosmic salt, the same reactions are produced.
With carbonate of soda, tellurous acid fuses upon platinum wire to a
clear colorless bead, which is white when cold. Upon charcoal it is
reduced, and forms _tellur-sodium_, which is absorbed by the charcoal,
and metallic tellurium, which is volatilized, and deposits upon the
charcoal a white incrustation (tellurous acid).
If tellurous acid, finely powdered charcoal, and carbonate of soda are
mixed together, and the mixture be well ignited in a closed tube,
until fusion is effected, and a few drops of boiled water are brought
into the tube, they are colored purple, indicating the presence of
_tellur-sodium._
_Telluric Acid _(TeO^{3}) forms six-sided prismatic crystals. It has
not an acid, but rather a metallic taste. It changes blue litmus paper
to red; is slowly soluble in water, and rather sparingly. Exposed to
a high temperature, but not until glowing, the crystalline acid loses
its water, and acquires an orange color, but still it preserves its
crystalline form, although no longer soluble in water, and is in fact
so much changed in its properties as to present the instance of an
isomeric modification.
If telluric acid is heated gently in a closed tube, it loses water and
turns yellow. Heated still more strongly, it becomes milk-white,
oxygen is expelled, and it is converted into tellurous acid. The
presence of oxygen can be recognized by the more lively combustion
which an ignited splinter of wood undergoes when held in it. Telluric
acid produces the same reactions with the blowpipe reagents as
tellurous acid.
SEVENTH GROUP.--LEAD, BISMUTH, TIN.
The oxides of these metals are also reduced to the metallic state by
fusion with soda upon charcoal in the flame of reduction, but they are
volatilized only after a continued blast, and a sublimate is thrown
upon the charcoal.
(_a._) _Lead_ (Pb).--This metal occurs in considerable quantity in
nature, chiefly as galena or lead-glance (sulphide of lead). Likewise,
but more rarely, as a carbonate; also as a sulphate, and sometimes
combined with other acids and metals.
In the metallic state, lead is of a bluish-grey color, high lustre,
and sp. gr. 11.4. It is soft, and communicates a stain to paper. It is
malleable, ductile, but has very little tenacity. It melts at about
612°. Exposed to the air it soon tarnishes, being covered with a grey
matter, which some regard as a suboxide (Pb^{2}O), and others as
simply a mixture of lead and protoxide. At a glowing heat it is
oxidized to a protoxide, and at a white heat it is volatilized. It is
insoluble in most acids. It is, however, soluble in nitric acid, but
without decomposing water.
(_L._) _Protoxide of Lead_ (PbO).--It is an orange-colored powder,
which melts at a glowing temperature, and forms a lamellar mass after
cooling. Protoxide of lead absorbs oxygen from the atmosphere while
melting, which is given off again by cooling. Being exposed for a
longer while to the air, it absorbs carbonic acid and water, and
becomes white on the surface. It is soluble in nitric acid and caustic
alkalies. It forms with most acids insoluble salts. It is slightly
soluble in pure water, but not in water which contains alkaline salts.
This hydrate is white.
([beta].) _Red Oxide of Lead_ (PbO^{2}, PbO).--It forms a puce-colored
powder. It is insoluble in caustic alkalies. Hydrochloric acid
dissolves it and forms a yellow liquid, which is soon decomposed into
chloride of lead and chlorine. It is reduced by ignition to the
protoxide.
([gamma].) _Peroxide of Lead _(PbO^{2}).--It is a dark-brown powder.
It yields with hydrochloric acid the chloride of lead and chlorine
gas. When heated it liberates oxygen, and is reduced to the protoxide.
Lead combinations give the following reactions before the blowpipe:
Metallic lead tarnishes when heated in the oxidation flame, and is
instantly covered with a grey matter, consisting of the protoxide and
the metal. It fuses quickly, and is then covered with a
yellowish-brown protoxide until all the lead is converted into the
protoxide, which melts to a yellow liquid. In the reduction flame and
upon charcoal, it is volatilized, while the charcoal becomes covered
with a yellow sublimate of oxide. A little distance from the assay,
this sublimate appears white (carbonate of lead). Protoxide of lead
melts in the flame of oxidation to a beautiful dark yellow bead. In
the flame of reduction, and upon charcoal, it is reduced with
intumescence to metallic lead, which is volatilized by a continued
blast, and sublimates on charcoal, as mentioned above.
Red oxide of lead turns black when heated in the glass tube closed at
one end, and liberates oxygen, which is easily detected by the
introduction of an ignited splinter, when a more lively combustion of
the wood proves the presence of uncombined oxygen. The red oxide in
this case is reduced to the protoxide. Heated upon platinum foil, it
first turns black, is reduced to the protoxide, and melts into a dark
yellow liquid. In the reduction flame, upon charcoal, it is reduced to
the metal with intumescence. After a continued blast, a yellow
sublimate of protoxide is produced upon the charcoal, and at a little
distance off, around this sublimate, a white one of carbonate of lead
is produced. This sublimate disappears when touched by the flame of
reduction, while it communicates an azure blue-tinge to the external
flame. This is likewise the case with the peroxide of lead.
The different oxides of lead produce with the blowpipe reagents the
same reactions.
_Borax_ dissolves lead compounds with the greatest readiness upon
platinum wire in the oxidation flame to a transparent bead, which is
yellow when hot, but colorless after being cooled. With the addition
of more of the lead oxide, it becomes opalescent. When heated by the
intermittent flame, and with still more of the oxide, it acquires a
yellow enamel after cooling. Heated upon charcoal, in the flame of
reduction, the bead spreads and becomes opaque. After a continued
blast, all the oxide is reduced with effervescence to metallic lead,
which melts and runs towards the edges of the bead, while the bead
again becomes transparent.
_Microcosmic Salt_ dissolves oxides of lead upon platinum wire in the
flame of oxidation easily to a clear, colorless bead, which appears,
when highly saturated, yellow while hot. A saturated bead becomes
enamel-like after cooling. The bead appears in the flame of reduction,
and upon charcoal, of a greyish color and dull. By the addition of
more oxide, a yellow sublimate of protoxide is produced upon the
charcoal. By the addition of tin, the bead appears of a darker grey,
but it is never quite opaque.
_Carbonate of Soda_ dissolves oxide of lead in the flame of oxidation
upon platinum wire quite readily to a transparent bead, which becomes
yellow when cooling, and is opaque. Upon charcoal in the flame of
reduction, it is rapidly reduced to metallic lead, which yields,
after a continued blast, a yellow sublimate of oxide upon the
charcoal.
(_b._) _Bismuth_ (Bi).--This metal occurs mostly in the metallic
state, and less frequently as the sulphide. In the pure metallic
state, it is of a reddish-white color and great lustre. It
crystallizes in cubes. It is brittle, and may be readily pulverized.
It melts at 476°, and is volatilized at a white heat. It is soluble in
nitric acid, and forms the nitrate of bismuth.
([alpha].) _Oxide of Bismuth _(Bi^{2}O^{3}).--This oxide is a light
yellow powder, fusible at a red heat, insoluble in caustic potash and
ammonia. It is the base of the salts of bismuth. Its hydrate is white,
and easily soluble in acids. The addition of water causes these
solutions to become milky, because they are decomposed into a soluble
acidulous and an insoluble basic salt of bismuth.
([beta].) _Peroxide of Bismuth_ (BiO^{2}) is a dark-colored powder,
completely soluble in boiling nitric acid, and yielding oxygen;
produces, with hydrochloric acid, chlorine gas. It can be heated up to
the temperature of 620° without being decomposed; but, exposed to a
temperature of 630° it yields oxygen. Mixed with combustible
substances, it glows with brightness.
([gamma].) _Bismuthic Acid _(Bi^{2}O^{5}) is a brown powder similar to
the peroxide, but is converted by boiling nitric acid into a green,
scarcely soluble substance (Bi^{2}O^{3}, Bi^{2}O^{5}). Its hydrate is
of a red color.
BLOWPIPE REACTIONS.--Metallic bismuth is converted, when exposed upon
platinum wire to the flame of oxidation, into a dark brown oxide,
which turns light yellow while cooling. It is slowly volatilized when
heated, and a yellow sublimate of oxide is produced upon the charcoal.
Oxide of bismuth melts upon platinum foil in the flame of oxidation
very easily into a dark-brown liquid, which changes to a light yellow
while cooling. By too strong a heat, it is reduced and penetrates the
platinum foil.
Upon charcoal, in the flame of oxidation and of reduction, it is
reduced to metallic bismuth, which melts into one or more globules.
By a continued blast they are slowly volatilized, and produce a yellow
sublimate of oxide upon the charcoal, beyond which a white sublimate
of carbonate of bismuth is visible. These sublimates disappear in the
flame of reduction, but without communicating any color to it.
_Borax_ dissolves oxide of bismuth upon platinum wire, in the flame of
oxidation, easily to a clear yellow bead, which appears colorless
after cooling. By the addition of more oxide, the hot bead becomes
orange. It turns more yellow while cooling, and when cool is
opalescent. Upon charcoal in the flame of reduction, the bead becomes
turbid and greyish colored. The oxide is reduced with intumescence to
the metallic state, and the bead becomes clear again. The addition of
tin promotes the reduction.
_Microcosmic Salt_ dissolves oxide of bismuth upon platinum wire, in
the flame of oxidation, to a yellow bead, which becomes colorless
after cooling. By the addition of more oxide, the bead is
yellowish-brown while hot, and colorless after cooling, but not quite
transparent. This bead becomes enamelled when heated by the
intermittent flame; also, by the addition of still more of the oxide,
after it is cooled.
Upon charcoal, in the flame of reduction, and particularly with the
addition of tin, the bead is colorless and transparent while hot, but
while cooling becomes of a dark-gray color and opaque.
Oxide of bismuth is reduced, by fusion with carbonate of soda, as well
in the oxidating as in the reducing flame, instantly to metallic
bismuth.
As the above mentioned higher oxides of bismuth are converted by
ignition into oxide of the metal and free oxygen, they have the same
behavior before the blowpipe.
As bismuth occurs mostly in the metallic form, it is necessary to know
how to distinguish it from metals similar to it. Its brittleness
distinguishes it from lead, zinc and tin, as they are readily
flattened by a stroke of the hammer, while bismuth is broken to
pieces. Bismuth, in this latter respect, might perhaps be mistaken
for antimony or tellurium; but, by the following examination, it is
easy to separate bismuth from antimony or tellurium.
1. Neither bismuth nor antimony sublimates when heated in a glass tube
closed at one end. At a temperature which is about to fuse the glass,
tellurium yields a small quantity of a white vapor (some tellurium is
oxidized to tellurous acid by the oxygen of the air in the tube).
After that, a grey metallic sublimate settles on the sides of the
tube.
2. Heated in an open tube, antimony yields a white vapor, which coats
the inside of the glass tube, and can be driven by heat from one part
of the tube to another without leaving a residue. The metallic globule
is covered with a considerable quantity of fused oxide. Tellurium
produces, under the same circumstances, an intense vapor, and deposits
on the glass a white powder, which melts by heat into globules that
run over the glass. The metallic globules are covered by fused,
transparent, and nearly colorless oxide, which becomes white while
cooling. By a high temperature, and with little access of air,
metallic tellurium sublimes with the deposition of a grey powder.
Bismuth produces, under similar treatment, scarcely any vapor, unless
it is combined with sulphur. The metal is enveloped by fused oxide of
a dark yellow color, which appears light yellow after being cooled. It
acts upon the glass, and dissolves it.
3. Upon charcoal, exposed to the blowpipe flame, the three metals are
volatilized, and yield a sublimate upon the charcoal. That of antimony
is white, while those of bismuth and tellurium are dark yellow. By
exposing them to the flame of reduction, the sublimate of tellurium
disappears and communicates an intense green color to the flame. The
antimony incrustation gives a feeble greenish-blue color, while the
sublimate of bismuth gives no perceptible color in the light. It is,
however, worthy of notice that if the operation takes place in the
dark, a very pale blue flame will be seen with the bismuth.
(_c._) _Tin_ (Sn).--This metal does not occur in nature in the
metallic state, very seldom in the sulphide, but chiefly in the oxide
(tinstone). In the metallic state it is silver-white, possesses a very
high lustre, is soft (but harder than lead), ductile, but has not much
tenacity, and it is very malleable. The metal when it is cast gives a
peculiar creaking noise when twisted or bent, which proceeds from the
crystalline structure of the metal. This crystallization is quite
clearly manifested by attacking the surface of the metal, or that of
tin plate, with acids.
Tin is very slightly tarnished by exposure to the air. It fuses at
442°, and becomes grey, being a mixture of the oxide and the metal. At
a high temperature even, tin is but little subject to pass off as
vapor. It is soluble in aqua regia, and with the liberation of
hydrogen, in hot sulphuric and hydrochloric acids, and in cold dilute
nitric acid, without decomposing water, or the production of a gas,
while nitrate of tin and nitrate of ammonia are formed. Concentrated
nitric acid converts tin into insoluble tin acids.
([alpha].) _Protoxide of Tin_ (SnO) is a dark-grey powder. Its hydrate
is white, and is soluble in caustic alkalies. When this solution is
heated, anhydrous crystalline black protoxide is separated. The
soluble neutral salts of tin-protoxide are decomposed by the addition
of water, and converted into acid soluble, and basic insoluble salts.
When protoxide of tin is ignited with free access of air, it takes
fire and is converted with considerable intensity into the acids,
producing white vapors. This is likewise the case if it is touched by
a spark of fire from steel. The hydrate of the protoxide of tin can be
ignited by the flame of a candle, and glows like tinder.
([beta].) _Sesquioxide of Tin_ (Sn^{2}O^{3}) is a greyish-brown
powder. Its hydrate is white, with a yellow tinge. It is soluble in
aqua ammonia and in hydrochloric acid; this solution forms with
solution of gold the "purple of Cassius."
([gamma].) _Stannic Acid_ (peroxide, SnO^{2}).--This acid occurs in
nature crystallized in quadro-octahedrons, of a brown or an intense
black color, and of great hardness (tinstone). Artificially prepared,
it is a white or yellowish-white powder. It exists in two distinct or
isomeric modifications, one of which is insoluble in acids (natural
tin-acid) while the other (tin-acid prepared in the wet way) is
soluble in acids. By ignition the soluble acid is converted into the
insoluble. Both modifications form hydrates.
_Reactions before the Blowpipe._--Metallic tin melts easily. It is
covered in the flame of oxidation into a yellowish-white oxide, which
is carried off sometimes by the stream of air which propels the flame.
In the reduction flame, and upon charcoal, melting tin retains its
metallic lustre, while a thin sublimate is produced upon the charcoal.
This sublimate is light-yellow while hot, and gives a strong light in
the flame of oxidation, and turns white while cooling. This sublimate
is found near to the metal, and cannot be volatilized in the oxidation
flame. In the flame of reduction it is reduced to metallic tin.
Sometimes this incrustation is so imperceptible that it can scarcely
be distinguished from the ashes of the charcoal. If such be the case,
moisten it with a solution of cobalt, and expose it to the flame of
oxidation, when the sublimate will exhibit, after cooling, a
bluish-green color.
Protoxide of tin takes fire in the flame of oxidation, and burns with
flame and some white vapor into tin acid, or stannic acid. In a strong
and continued reduction flame, it may be reduced to metal, when the
same sublimate above mentioned is visible. The sesquioxide of tin
behaves as the above.
Stannic acid, heated in the flame of oxidation, does not melt and is
not volatilized, but produces a strong light, and appears yellowish
while hot, but changing as it cools to a dirty-yellow white color. In
a strong and continued flame of reduction, it may be reduced likewise
to the metallic state, with the production of the same sublimate as
the above.
_Borax_ dissolves tin compounds in the flame of oxidation, and upon
platinum wire, very tardily, and in small quantity, to a transparent
colorless bead, which remains clear after cooling, and also when
heated intermittingly. But if a saturated bead, after being completely
cool, is exposed again to the flame of oxidation, at a low red heat,
the bead while cooling is opaque, loses its globular form, and
exhibits an indistinct crystallization. This is the case too in the
flame of reduction, but if the bead is highly saturated, a part of the
oxide is reduced.
_Microcosmic Salt_ dissolves the oxides in the flame of reduction very
tardily in a small quantity to a transparent colorless bead, which
remains clear while cooling. If to this bead sesquioxide of iron is
added in proper proportion, the sesquioxide loses its property of
coloring the bead, but of course an excess of the iron salt will
communicate to the bead its own characteristic color. In the flame of
reduction no further alteration is visible.
Tin-oxides combine with carbonate of soda, in the flame of oxidation
upon platinum wire, with intumescence to a bulky and confused mass,
which is insoluble in more soda. Upon charcoal, in the reduction
flame, it is easily reduced to a metallic globule. Certain compounds
of tin-oxides, particularly if they contain tantalum, are by fusion
with carbonate of soda reduced with difficulty; but by the addition of
some borax, the reduction to the metallic state is easily effected.
Tin-oxides exposed to the oxidation flame, then moistened with a
solution of cobalt, and exposed again to the flame of oxidation, will
exhibit, after having completely cooled, a bluish-green color.
EIGHTH GROUP.--MERCURY, ARSENIC.
These two metals are volatilized at a temperature lower than that of a
red heat, and produce, therefore, no reactions with borax and
microcosmic salt. Their oxides are easily reduced to the metallic
state.
(_a._) _Mercury_ (Hg).--This metal occurs in nature chiefly combined
with sulphur as a bisulphide.
It occurs still more rarely in the metallic form, or combined with
silver, selenium, or chlorine.
Mercury, in the metallic state, has a strong lustre, and is liquid at
ordinary temperatures, whereby it is distinguished from any other
metal. It freezes at 40° and boils at 620°, but it evaporates at
common temperatures. Pure mercury is unalterable. Upon being exposed
to the air, it tarnishes only by admixture with other metals, turns
grey on the surface, and loses its lustre. It is soluble in cold
nitric acid and in concentrated hot sulphuric acid, but not in
hydrochloric acid.
([chi].) _Protoxide of Mercury_ (Hg^{2}O).--It is a black powder,
which is decomposed by ignition into metallic mercury and oxygen. By
digestion with certain acids, and particularly with caustic alkalies,
it is converted into metallic mercury and peroxide. Some neutral salts
of the protoxide are only partly soluble in water, as they are
converted into basic insoluble and acid soluble salts.
Protoxide of mercury is completely insoluble in hydrochloric acid. Its
neutral salts change blue litmus paper to red.
([beta].) _Peroxide of Mercury_ (HgO).--This oxide exists in two
allotropic modifications. One is of a brick-red color, and the other
is orange. Being exposed to heat, they turn black, but regain their
respective colors upon cooling. They are decomposed at a high
temperature into metallic mercury and oxygen. They yield with acids
their own peculiar salts.
Mercury, in the metallic form, can never be mistaken for any other
metal in consequence of its fluid condition at ordinary temperatures.
Exposed to the blowpipe flame, it is instantly volatilized. This is
also the case with it when combined with other metals. The oxides of
mercury are, in the oxidation and reduction flames, instantly reduced
and volatilized. They do not produce any alteration with fluxes, as
they are volatilized before the bead melts. Heated with carbonate of
soda in a glass tube closed at one end, they are reduced to metallic
mercury, which is volatilized, and condenses upon a cool portion of
the tube as a grey powder. By cautious knocking against the tube, or
by rubbing with a glass rod, this sublimate can be brought together
into one globule of metallic mercury. Compounds of mercury can be most
completely reduced by a mixture of neutral oxalate of potassa and
cyanide of potassium. If the substance under examination contains such
a small quantity of mercury that it cannot be distinguished by
volatilization, a strip of gold leaf may be attached to an iron wire,
and introduced during the experiment in the glass tube. The smallest
trace of mercury will whiten the gold leaf in spots.
(_b._) _Arsenic_ (As).--This metal occurs in considerable quantity in
nature, chiefly combined with sulphur or metals.
Arsenic, in the metallic state, is of a whitish-grey color, high
lustre, and is crystalline, of a foliated structure, and is so brittle
that it can be pulverized. It does not melt, but is volatilized at
356°. Its vapor has a strong alliaceous odor. Arsenic sublimes in
irregular crystals. By exposure to the air it soon tarnishes, and is
coated black. Being mixed with nitrate of potassa and inflamed, it
detonates with vehemence. Mixed with carbonate of potassa, it is
inflamed by a stroke of the hammer, and detonates violently.
Heated in oxygen gas, it is inflamed, and burns with a pale blue flame
to arsenious acid.
([beta].) _Arsenious Acid_ (AsO^{3}).--This acid crystallizes in
octahedrons, or, when fused, forms a colorless glass, which finally
becomes opaque and enamel-like, or forms a white powder. It sublimes
without change or decomposition. When heated for a longer while below
the temperature of sublimation, it melts into a transparent,
colorless, tough glass. The opaque acid is sparingly soluble in cold
water, and still more soluble in hot water. It is converted, by
continued boiling, into the transparent acid, which is much more
soluble in water. Arsenious acid is easily dissolved by caustic
potassa. It is also soluble in hydrochloric acid. This acid occurs
associated with antimonious acid, protoxide of tin, protoxide of lead,
and oxide of copper. It occurs likewise in very small quantity in
ferruginous mineral springs.
([gamma].)_Arsenic Acid_ (AsO^{5}) is a white mass, which readily
absorbs moisture and dissolves. It will not volatilize at a low red
heat, nor will it decompose. Exposed to a strong heat, it is
decomposed, yielding oxygen, and passing into arsenious acid.
_Reactions before the Blowpipe._
Metallic arsenic, heated in a glass tube closed at one end, yields a
black sublimate of a metallic lustre, and at the same time gives out
the characteristic alliaceous odor. This is the case too with alloys
of arsenic, if there is a maximum quantity of arsenic present.
When heated in a glass tube open at both ends, metallic arsenic is
oxidized to arsenious acid, which appears as a white crystalline
sublimate on the sides of the glass tube. This deposit will occur at
some distance from the assay, in consequence of the great volatility
of the arsenic. The sublimate can be driven from one place upon the
tube to another, by a very low heat. Alloys of arsenic are converted
into basic arseniates of metal oxides, while surplus arsenic is
converted into arsenious acid, which sublimes on the tube. If too much
arsenic is used for this experiment, a dark-brown incrustation will
sublime upon the sides of the tube which will give an alliaceous
smell. If this sublimate should be deposited near the assay, then it
resembles the white sublimate of arsenious acid.
Heated upon charcoal, metallic arsenic is volatilized before it melts,
and incrusts the charcoal in the flame of oxidation as a white deposit
of arsenious acid. This sublimate appears sometimes of a greyish
color, and takes place at some distance from the assay. When heated
slightly with the blowpipe flame, this sublimate is instantly driven
away, and being heated rapidly in the reduction flame, it disappears
with a light blue tinge, while the usual alliaceous or garlic smell
may be discerned.
Arsenious acid sublimes in both glass tubes very readily, as a white
crystalline sublimate. These crystals appear to be regular octahedrons
when observed under the microscope. Upon charcoal it instantly
volatilizes, and when heated, the characteristic garlic smell may be
observed.
Arsenic acid yields, heated strongly in a glass tube closed at one
end, oxygen and arsenious acid, the latter of which sublimes in the
cool portions of the tube. Compounds of arsenic produce, in
consequence of their volatility, no reactions with fluxes. Being
heated upon charcoal with carbonate of soda, they are reduced to
metallic arsenic which may be detected by the alliaceous odor peculiar
to all the arsenic compounds when volatilized.
NINTH GROUP.--COPPER, SILVER, GOLD.
These metals are not volatile, neither are their oxides. They are
reduced to the metallic state, by fusion with carbonate of soda, when
they melt to a metallic grain. The oxides of silver and gold are
reduced _per se_ to the metallic state by ignition. In the reduction
of the oxides of this group, no sublimate is visible upon the
charcoal.
(_a._) _Copper_ (Cu).--This metal occurs in the metallic state, also
as the protoxide, and as oxides combined with acids in different salts
(carbonate of copper as malachite, etc.) The sulphide of copper is the
principal ore of copper occurring in nature. In the metallic state,
copper is of a red color, has great lustre and tenacity, is ductile
and malleable, and crystallizes in octahedrons and cubes. It melts at
a bright red heat, is more difficult than silver to fuse, but fuses
more readily than gold. It absorbs oxygen while melting. There arises
from its surface a fine dust of metallic globules, which are covered
with the protoxide. The surface of the metal is likewise covered with
the protoxide. Copper exposed to moist air tarnishes, and is
converted into hydratic carbonate of copper. When ignited in the open
air, it is soon covered with the brownish-red protoxide.
([chi].) _Protoxide of Copper_ (Cu^{2}O).--This oxide occurs in
nature, crystallized in octahedrons of a ruby-red color, of a lamellar
structure, and transparent. Artificially prepared, it forms a powder
of the same color. It is decomposed by dilute acids into salts of
peroxide and metal. It is converted by ignition, with free access of
air, into peroxide.
([beta].) _Oxide of Copper_ (CuO).--This oxide is a dark-brown or
black powder. It is dissolved by acids, with a blue or green-colored
solution. It is soluble in aqua ammonia, and the solution is of a dark
blue color.
_Reactions before the Blowpipe._--Oxide of copper exposed upon
platinum wire to the inmost flame (the blue flame), communicates to
the external flame a green color. Heated upon charcoal in the
oxidation flame, it melts to a black ball, soon spreads over the
charcoal, and is partially reduced.
Exposed to the reduction flame, at a temperature which will not melt
copper, it is reduced with a bright metallic lustre, but as soon as
the blast ceases, the surface of the metal becomes oxidized, and
appears dark brown or black. If the temperature is continued still
higher, it melts to a metallic grain.
_Borax_ dissolves the oxide of copper in the flame of oxidation to a
clear green-colored bead, even if the quantity of oxide be quite
small, but by cooling, the bead becomes blue. In the flame of
reduction upon platinum wire, the bead soon becomes colorless, but
while cooling presents a red color (protoxide of copper). This bead is
opaque, but, if too much of the oxide is added, a part of it is
reduced to metal, which is visible by breaking the metallic grain.
Upon charcoal, the oxide is reduced to the metal, and the bead appears
colorless after cooling. With the addition of some tin, the bead
becomes brownish-red and opaque after cooling.
_Microcosmic Salt_ dissolves oxide of copper in the flame of oxidation
to a green bead, not so intensely colored as the borax bead. In the
reduction flame the bead, if pretty well saturated, becomes dark-green
while hot, and brownish-red when cool, opaque and enamel-like. If the
oxide is so little that no reaction is visible, by the addition of
some tin, the bead appears colorless while hot, and dark brownish-red
and opaque when cold.
_Carbonate of Soda_ dissolves oxide of copper in the oxidation flame
upon platinum wire, to a clear, green bead, which loses its color when
cooling, and becomes opaque.
Upon charcoal, it is reduced to the metal, the soda is absorbed by the
charcoal, and the metallic particles melt with sufficient heat to a
grain.
(_b._) _Silver_ (Ag).--This metal occurs in nature in the metallic
state, and in combination with other metals, particularly with lead.
It also occurs as the sulphide in several mines. It crystallizes in
cubes and octahedrons; is of a pure white color, great lustre, is very
malleable and ductile, and is softer than copper, but harder than
gold. It is not oxidizable, neither at common temperatures nor at
those which are considerably higher. It is soluble in dilute nitric
acid, and in boiling concentrated sulphuric acid.
([chi].) _Protoxide of Silver_ (Ag^{2}O).--It is a black powder. It is
converted by acids and ammonia into oxide and metal.
([beta].) _Oxide of Silver_ (AgO).--It is a greyish-brown or black
powder, and is the base of the silver salts. With aqua ammonia, it is
converted into the black, fulminating silver.
([gamma].) _Superoxide or Binoxide of Silver_ (AgO^{2}).--This oxide
occurs in black needles or octahedral crystals of great metallic
lustre. It is dissolved by the oxygen acids with the disengagement of
oxygen gas.
_Behavior before the Blowpipe._--When exposed to the flames of
oxidation and reduction, the oxides of silver are instantly reduced to
the metallic state.
_Borax_ dissolves silver-oxides upon platinum wire in the oxidation
flame but partially, while the other portion is reduced, the bead
appearing opalescent after cooling, in correspondence to the degree of
saturation. The bead becomes grey in the flame of reduction, the
reduced silver melting to a grain, and the bead is rendered clear and
colorless again.
_Microcosmic Salt_ dissolves oxides of silver in the flame of
oxidation upon platinum wire to a transparent yellowish bead, which
presents, when much of the oxide is present, an opalescent appearance.
In the flame of reduction, the reaction is analogous to that of borax.
By fusion with carbonate of soda in the oxidation and reduction
flames, the silver oxides are instantly reduced to metallic silver,
which fuses into one or more grains.
(_c._) _Gold_ (Au).--This metal occurs mostly in the metallic state,
but frequently mixed with ores, and with other metals. Gold
crystallizes in cubes and octahedrons, is of a beautiful yellow color,
great lustre, and is the most malleable and ductile of all the metals.
It melts at a higher temperature than copper, gives a green colored
light when fused, and contracts greatly when cooling. It does not
oxidize at ordinary temperatures, nor when heated much above them. It
is soluble in nitro-hydrochloric acid (_aqua regia_).
([chi].) _Protoxide of Gold_ (Au^{2}O).--This oxide is a dark violet
colored powder which is converted by a temperature of 540° into
metallic gold and oxygen. It is only soluble in aqua regia. Treated
with hydrochloric acid, it yields the chloride of gold and the metal.
With aqua ammonia, it yields the fulminating gold, which is a blue
mass and very explosive.
([chi].) _Peroxide of Gold_ (Au^{2}O^{3}).--This oxide is an
olive-green or dark brown powder, containing variable quantities of
water. Decomposed at 530°, it yields metallic gold and oxygen.
_Reactions before the Blowpipe._--Oxides of gold are reduced, in both
the oxidation and reduction flames, to the metal, which fuses to
grains.
_Borax_ does not dissolve it, but it is reduced to the metallic state
in this flux in either flame. The reduced metal fuses upon charcoal to
a grain.
_Microcosmic Salt_ presents the same reactions as borax.
When fused with soda, upon charcoal, the soda is absorbed, and the
gold remains as a metallic grain.
TENTH GROUP.--MOLYBDENUM, OSMIUM.
These metals are not volatile, and are infusible before the blowpipe;
but some of their oxides are volatile, and can be reduced to an
infusible metallic powder.
(_a._) _Molybdenum_ (Mo) occurs in the metallic state; also combined
with sulphur, or as molybdic acid combined with lead. It is a white,
brittle metal, and is unaltered by exposure to the air. When heated
until it begins to glow, it is converted into a brown oxide. Heated at
a continued dull red heat, it turns blue. At a higher temperature, it
is oxidized to molybdic acid, when it glimmers and smokes, and is
converted into crystallized molybdic acid upon the surface.
([chi].) _Protoxide of Molybdenum_ (MoO).--This oxide is a black
powder.
([chi].) _Deutoxide of Molybdenum_ (MoO^{2}).--This oxide is a dark
copper-colored crystalline powder.
_Reactions before the Blowpipe._--Metallic molybdenum, its protoxide
and binoxide, are converted in the oxidation flame into molybdic acid.
This acid fuses in the flame of oxidation to a brown liquid, which
spreads, volatilizes, and sublimes upon the charcoal as a yellow
powder, which appears crystalline in the vicinity of the assay. This
sublimate becomes white after cooling. Beyond this sublimate there is
visible a thin and not volatile ore of binoxide, after cooling; this
is of a dark copper-red color, and presenting a metallic lustre.
Heated in a glass tube, closed at one end, it melts to a brown mass,
vaporizes and sublimates to a white powder upon a cool portion of the
tube. Immediately above the assay, yellow crystals are visible; these
crystals are colorless after cooling, and the fused mass becomes light
yellow-colored and crystalline.
Upon platinum foil, in the flame of oxidation, it melts and vaporizes,
and becomes light yellow and crystalline after cooling. In the
reduction flame it becomes blue, and brown-colored if the heat is
increased.
Upon charcoal, in the reduction flame, it is absorbed by the charcoal;
and, with an increase of the temperature, it is reduced to the metal,
which remains as a grey powder after washing off the particles of
charcoal.
_Borax_ dissolves it, in the oxidation flame, upon platinum wire
easily, and in great quantity, to a clear yellow, which becomes
colorless while cooling. By the addition of more of the molybdenic
acid the bead is dark yellow, or red while hot, and opalescent when
cold. In the reduction flame, the color of the bead is changed to
brown and transparent. By the addition of more of the acid, it becomes
opaque.
_Microcosmic Salt_ dissolves it in the oxidation flame, upon platinum
wire, to a clear, yellowish-green bead, which becomes colorless after
cooling. In the reduction flame the bead is very dark and opaque, but
becomes of a bright green after cooling. This is the case likewise
upon charcoal.
_Carbonate of Soda_ dissolves it upon platinum wire in the oxidation
flame with intumescence, to a clear bead, which appears milk-white
after cooling. Upon charcoal the soda and the molybdic acid are
absorbed, the latter is reduced to the metallic state, the metal
remaining as a grey powder after washing off the particles of
charcoal. When molybdic acid, or any other oxide of this metal, is
exposed upon platinum wire, or with platinum tongs, to the point of
the blue flame, a yellowish-green color is communicated to the
external flame. If also any of the compounds of molybdenum are mixed
in the form of a powder with concentrated sulphuric acid and alcohol,
and the latter inflamed, the flame of the alcohol appears colored
green.
(_c._) _Osmium_ (Os).--This metal occurs associated with platinum. It
is of a bluish-grey color, and is very brittle. Ignited in the open
air, it is oxidized to volatile osmic acid, which is possessed of a
pungent smell, and affects the eyes. It communicates a bright white
color to the flame of alcohol. Osmium oxide (OsO^{2}) is converted in
the oxidation flame to osmic acid, which is volatilized with a
peculiar smell, leaving a sublimate.
In the reduction flame it is reduced to a dark-brown infusible
metallic powder. It produces no reactions with fluxes. Carbonate of
soda reduces it upon charcoal to an infusible metallic powder, which
appears, after washing off the particles of charcoal, of a dark-brown
color.
ELEVENTH GROUP.--PLATINUM, PALLADIUM, IRIDIUM, RHODIUM, RUTHENIUM.
These metals are infusible before the blowpipe. They are not volatile,
nor are they oxidizable. Their oxides are, in both flames, reduced to
a metallic and infusible powder. They give no reactions with fluxes,
but are separated in the metallic form. These metals are generally
found associated together in the native platinum, also with traces of
copper, lead, and iron.
The metal palladium is found native, associated with iridium and
platinum. This metal generally occurs in greatest quantity in Brazil.
The metal rhodium is found along with platinum, but in very small
quantities.
Iridium occurs in nature associated with osmium, gold, and platinum,
in the mines of Russia. Its great hardness has rendered it desirable
for the points of gold pens. In South America this metal is found
native, associated with platinum and osmium. The latter metal,
associated with platinum and iridium, has been found in South America.
As these metals will not oxidize or dissolve, they cannot be separated
from each other by the blowpipe with the reagents peculiar to that
species of analysis. It is true that colors may be discerned in the
beads, but these tints proceed from the presence of small traces of
copper, iron, etc.
The ore of osmium and iridium can be decomposed, and the former
recognized by its fetid odor. This metal, strongly ignited in a glass
tube with nitrate of potash, is converted to the oxide of osmium,
which gives an odor not unlike the chloride of sulphur.
As the metals of this group are very rare ones, especially the last
four ones, we shall not devote an especial division to each of them.
For a more detailed statement of their reactions, the student is
referred to the large works upon blowpipe analysis.
CLASS III.
NON-METALLIC SUBSTANCES.
1. _Water_--2. _Nitric Acid_--3. _Carbon_--4. _Phosphorus_
--5. _Sulphur_--6. _Boron_--7. _Silicon_--8. _Chlorine_
--9. _Bromine_--10. _Iodine_--11. _Fluorine_--12. _Cyanogen_
--13. _Selenium_.
(1.) _Water_ (HO).--Pure distilled water is composed of one volume of
oxygen, and two volumes of hydrogen gases; or, by weight, of one part
of hydrogen to eight parts of oxygen gases. Water is never found pure
in nature, but possessing great solvent properties, it always is found
with variable proportions of those substances it is most liable to
meet with, dissolved in it. Thus it derives various designations
depending upon the nature of the substance it may hold in solution, as
lime-water, etc.
In taking cognizance of water in relation to blowpipe analysis, we
regard it only as existing in minerals. The examination for water is
generally performed thus: the substance may be placed in a dry tube,
and then submitted to heat over a spirit-lamp. If the water exists in
the mineral mechanically it will soon be driven off, but if it exists
chemically combined, the heat will fail to drive it off, or if it
does, it will only partially effect it. The water will condense upon
the cool portions of the tube, where it can be readily discerned. If
the water exists chemically combined, a much stronger heat must be
applied in order to separate it.
Many substances may be perhaps mistaken for water by the beginner,
such as the volatile acids, etc.
(2.) _Nitric Acid_ (NO^{5}).--Nitric acid occurs in nature in potash
and soda saltpetre. These salts are generally impure, containing lime,
as the sulphate, carbonate and nitrate, and also iron in small
quantity. The soda saltpetre generally contains a quantity of the
chloride of sodium. The salts containing nitric acid deflagrate when
heated on charcoal. Substances containing nitric acid may be heated in
a glass tube closed at one end, by which the characteristic red fumes
of nitrous acid are eliminated. If the acid be in too minute a
quantity to be thus distinguished, a portion of the substance may be
intimately mixed with some bisulphate of potash, and treated as above.
The sulphuric acid of the bisulphate combines with the base, and
liberates the nitric acid, while the tube contains the nitrous acid
gas.
The nitrate of potassa, when heated in a glass tube, fuses to a clear
glass, but gives off no water. When fused on platinum wire, it
communicates to the external flame the characteristic violet color.
When fused and ignited on charcoal, its surface becomes frothy,
indicating the nitric acid.
(3.) _Carbon_ (C).--Carbon is found in nature in the pure crystallized
state as the diamond. It occurs likewise in several allotropic states
as graphite, plumbago, charcoal, anthracite, etc. It exists in large
quantities combined with oxygen as carbonic acid.
The diamond, although combustible, requires too high a heat for its
combustion to enable us to burn it with the blowpipe. When excluded
from the air, it may be heated to whiteness without undergoing fusion,
but with the free access of air it burns at a temperature of 703° C,
and is converted into carbonic acid. If mixed with nitre, the potassa
retains the carbonic acid, and the carbon may be thus easily
estimated. If a mineral containing carbonic acid is heated, the gas
escapes with effervescence, or a strong mineral acid as the
hydrochloric will expel the acid with the characteristic
effervescence.
(4.) _Phosphorus, Phosphoric Acid _(PO^{6}).--This acid occurs in a
variety of minerals, associated with yttria, copper, uranium, iron,
lead, manganese, etc. Phosphoric acid may be detected in minerals by
pursuing the following process: dip a small piece of the mineral in
sulphuric acid, and place it in the platinum tongs: this is heated at
the point of the blue flame, when the outer flame will become colored
of a greenish-blue hue. This color will not be mistaken for those of
boracic acid, copper, or baryta. Some of the phosphoric minerals, when
heated in the inner flame, will color the outer flame green.
If alumina be present with the phosphoric acid, the following wet
method should be adopted for the detection of the latter: the
substance should be powdered in the agate mortar with a mixture of six
parts of soda, and one and a half parts of silica. The entire mass
should now be placed on charcoal, and melted in the flame of
oxidation. The residue should be treated with boiling water, which
dissolves the phosphate and the excess of carbonate of soda, while the
silicate of alumina, with some of the soda, is left. The clear liquor
is now treated with acetic acid, and heated over the spirit-lamp, and
a small portion of crystallized nitrate of silver added; a
lemon-yellow precipitate of phosphate of silver is quickly developed.
Previous to the addition of the nitrate, the liquor should be well
heated; otherwise, a white precipitate of dipyrophosphate of silver
will be produced.
If the examination be of any of the metallic phosphides, the
substances should be powdered in the agate mortar, and fused with
nitrate of potassa on the platinum wire; the fused mass should be
treated with soda in the same manner as any substance containing
phosphoric acid. The metal and the phosphorus are oxidized, while the
phosphate of potassa is fused, and the metallic oxide separates.
(5.) _Sulphur_ (S).--Sulphur is found native in crystals It is
frequently found associated with lime, iron, silica, carbon, etc., and
combined extensively with metals.
The principal acid of sulphur (the sulphuric, SO^{3}) occurs combined
with the earths, the alkalies, and the metallic oxides. Native sulphur
is recognized, when heated upon charcoal, by its odor (sulphurous
acid) and the blue color of its flame. The compounds of sulphur may be
detected by several methods. If the substance is heated in a glass
tube, closed at one end, the yellow sublimate of sulphur will subside
upon the cool portions of the tube; if the substance should also
contain arsenic, the sublimate will present itself as a light brown
incrustation, consisting of the sulphide of arsenic.
If the assay is heated in the open glass tube, sulphurous acid will
thus be generated; but, if the gas is too little to be detected by the
smell, a strip of moistened litmus paper will indicate the presence of
the acid.
The assay will give off sulphurous fumes if heated in the flame of
oxidation.
If the powdered substance is fused with two parts of soda, and one
part of borax, upon charcoal, the sulphide of sodium is formed. This
salt, if moistened and applied to a polished silver surface, will
blacken it. The borax serves no other purpose than to prevent the
absorption of the formed sulphide of sodium by the charcoal. As
selenium will blacken silver in the manner above indicated, the
presence of this substance should be first ascertained, by heating the
assay; when, if it be present, the characteristic horse-radish odor
will reveal the fact.
Sulphuric acid may be detected by fusing the substance with two parts
of soda, and one part of borax, on charcoal, in the flame of
reduction; the mass must now be wetted with water, and placed in
contact with a surface of bright silver; when, if sulphuric acid be
present, the silver will become blackened.
Or the substance may be fused with silicate of soda in the flame of
reduction. In this case, the soda combines with a portion of the
sulphuric acid, which is then reduced to the sulphide, while the bead
becomes of an orange or red color, depending upon the amount of the
sulphuric acid present. If the assay should, however, be colored, then
the previous treatment should be resorted to.
(6.) _Boron, Boracic Acid_ (BO^{3}).--This acid occurs in nature in
several minerals combined with various bases, such as magnesia, lime,
soda, alumina, etc. Combined with water, this acid exists in nature as
the native boracic acid; this acid gives with test paper prepared from
Brazil wood, when moistened with water, a characteristic reaction, for
the paper becomes completely bleached. An alcohol solution turns
curcuma test paper brown. Heated on charcoal, it fuses to a clear
bead; but, if the sulphate of lime be present, the bead becomes opaque
upon cooling.
The following reaction is a certain one: the substance is pulverized
and mixed with a flux of four and a half parts of bisulphate of
potassa, and one part of pulverized fluoride of calcium. The whole is
made into a paste with water, and the assay is placed on the platinum
wire, and submitted to the point of the blue flame. While the assay is
melting, fluoboric gas is disengaged, which tinges the outer flame
green. If but a small portion of boracic acid is present, the color
will be quite evanescent.
(7.) _Silica, Silicic Acid_ (SiO^{3}).--This acid exists in the
greatest plenty, forming no inconsiderable portion of the solid part
of this earth. It exists nearly pure in crystallized quartz,
chalcedony, cornelian, flint, etc., the coloring ingredients of these
minerals being generally iron or manganese.
With _microcosmic salt_, silica forms a bead in the flame of oxidation
which, while hot, is clear, while the separated silica floats in it. A
platinum wire is generally used for the purpose, the end of it being
first dipped in the salt which is fused into a bead, after which the
silica must be added, and then the bead submitted to the flame of
oxidation.
The silicates dissolve in soda but partially, and then with
effervescence. If the oxygen of the acid be twice that of the base, a
clear bead will be obtained that will retain its transparency when
cold. If the soda be added in small quantity, the bead will then be
opaque. In the first instance, a part of the base which separates is
re-dissolved, and, therefore, the transparency of the glass; but, if
too large a quantity of the soda is added, the separation of the base
is sufficient to render the assay infusible.
(8.) _Chlorine_ (Cl).--Chlorine exists in nature always in
combination, as the chlorides of sodium, potassium, calcium, ammonium,
magnesia, silver, mercury, lead, copper, etc.
The chlorine existing in metallic chlorides may be detected as
follows: the wet way may be accomplished in the following manner. If
the substance is insoluble, it must be melted with soda to render it
soluble; if it be already soluble it must be dissolved in pure water,
and nitrate of silver added, when the one ten-thousandth part of
chlorine will manifest its presence by imparting a milky hue to the
fluid.
By the blowpipe, chlorine may be detected in the following manner:
Oxide of copper is dissolved in microcosmic salt on the platinum wire
in the flame of oxidation, and a clear bead is obtained. The substance
containing the chlorine is now added, and heat is applied. The assay
will soon be enveloped by a blue or purplish flame. As none of the
acids that occur in the mineral kingdom give this reaction, chlorine
cannot be confounded with them, for those which impart a color to the
flame, when mixed with a copper salt, will not do so when tested in
the microcosmic salt bead as above indicated.
If the assay is soluble in water, the following method may be
followed: a small quantity of sulphate of copper or iron is dissolved;
a few drops of the solution is placed upon a bright surface of silver,
and the metallic chloride added; when, if chlorine is present, the
silver is blackened. If the chloride is insoluble in water, it must be
rendered soluble by fusion upon a platinum wire with soda, and then
treated as above.[2]
[2] Plattner.
(9.) _Bromine_ (Br).--The bromide of magnesium and sodium exists in
many salt springs, and it is from these that the bromine of commerce
is obtained. The metallic bromides give the same reactions on silver
with the microcosmic bead and copper salt as the metallic chlorides.
The purplish color which, however, characterizes the chlorides, is
more inclined to greenish with the bromides. If the substance be
placed in a flask or glass tube, and fused with bisulphate of potassa,
over the spirit-lamp, sulphurous gas and bromine will be eliminated.
Bromine will be readily detected by its yellow color and its smell.
Bromine may be readily detected by passing a current of chlorine
through the fluid, after which ether is added and the whole is
agitated. The ether rises to the top, carrying with it the bromine in
solution; after being withdrawn, this ether is mixed with potassa, by
which the bromide and bromate of potassa are formed. The solution is
evaporated to dryness, the residue is fused in a platinum vessel, the
bromate is decomposed, while the bromide remains; this must be
distilled with sulphuric acid and the binoxide of manganese. A red or
brown vapor will then appear, indicating the presence of bromine; this
vapor will color starch paste--which may be put in the receiver on
purpose--of a deep orange color.
If, to a solution containing a bromide, concentrated sulphuric or
nitric acid be added, the bromine is liberated and colors the solution
yellow or red. The hypochlorites act in the same manner. The bromine
salts are coming into use extensively in photography, in consequence
of their greater sensitiveness to the action of light than the
chlorides alone.
(10.) _Iodine_ (I).--This element occurs in salt-springs, generally
combined with sodium; it also exists in rock-salt; it has likewise
been found in sea-water, also in a mineral from Mexico, in combination
with silver, and in one from Silesia, in combination with zinc. As
sea-water contains iodine, we would consequently expect to find it
existing in the sea-weeds, and it is generally from the ashes of these
that it is obtained in commerce.
When the metallic iodides are fused with the microcosmic salt and
copper, as previously indicated, they impart a green color to the
flame. This color cannot be mistaken for the color imparted to the
flame by copper alone. When the metallic iodides are fused in a glass
tube, closed at one end, with the bisulphate of potassa, the vapor of
iodine is liberated, and may be recognized by its characteristic
color. Those mineral waters containing iodine can be treated the same
as for bromine, as previously indicated, while the violet-colored
vapor of the iodine can be easily discerned. The nitrate of silver is
the best test for iodine, the yellow color of the iodide of silver
being not easily mistaken, while its almost insolubility in ammonia
will confirm its identity. The chloride of silver, on the contrary,
dissolves in ammonia with the greatest facility.
The reactions of iodine are similar to those of bromine with
concentrated sulphuric acid and binoxide of manganese, and with nitric
acid: The iodine is released and, if the quantity be not too great,
colors the liquid brown. If there be a considerable quantity of iodine
present, it is precipitated as a dark colored powder. Either of these,
when heated, gives out the violet-color of the iodine.
With starch paste free iodine combines, producing a deep blue
compound. If, however, the iodine be in very minute quantity, the
color, instead of being blue, will be light violet or rose color.
If to a solution of the sulphate of copper, to which a small portion
of sulphurous acid has been added, a liquid containing iodine and
bromine is poured in, a dirty, white precipitate of the subiodide of
copper is produced, and the bromine remains in the solution. The
latter may then be tested for the bromine by strong sulphuric acid.
(11.) _Fluorine_ (Fl).--This element exists combined with sodium,
calcium, lithium, aluminium, magnesium, yttrium, and cerium. Fluorine
also exists in the enamel of the teeth, and in the bones of some
animals. This element has a strong affinity for hydrogen, and,
therefore, we find it frequently in the form of hydrofluoric acid.
Brazil-wood paper is the most delicate test for hydrofluoric acid,
which it tinges of a light yellow color. Phosphoric acid likewise
colors Brazil paper yellow, but as this acid is not volatile at a heat
sufficient to examine hydrofluoric acid, there can be no mistake. If
the substance is supposed to contain this acid, it should be placed on
a slip of glass, and moistened with hydrochloric acid, when the test
paper may be applied, and the characteristic yellow color will
indicate the presence of the fluorine.
As hydrofluoric acid acts upon glass, this property may be used for
its detection. The substance may be put into a glass tube, and
sulphuric acid poured upon it in sufficient quantity to moisten it; a
slight heat applied to the tube will develop the acid, which will act
upon the glass of the tube. If the acid is retained in the mineral by
a feeble affinity, and water be present, a piece of it may be put in
the tube and heated, when the acid gas will be eliminated. The test
paper will indicate its presence, even before it has time to act upon
the glass. If the temperature be too high, fluosilicic acid is
generated, and will form a silicious incrustation upon the cool
portion of the tube.
If the fluorine is too minute to produce either of the above
reactions, then the following process, recommended by Plattner, should
be followed: the assay should be mixed with metaphosphate of soda,
formed by heating the microcosmic salt to dull redness. The mass must
then be placed in an open glass tube, in such a position that there
will be an access of hot air from the flame. Thus aqueous hydrofluoric
acid is formed, which can be recognized by its smell being more
suffocating than chlorine, and also by the etching produced by the
condensation of vapor in the tube. Moist Brazil paper, applied to the
extremity of the tube, will be instantly colored yellow.
Merlet's method for the detection of this acid is the following:[3]
Pulverize the substance for examination, then triturate it to an
impalpable powder, and mix it with an equal part of bisulphate of
potassa. Heat the mass gradually in a moderately wide test-tube. The
judicious application of heat must be strictly observed, for if the
operator first heats the part of the tube where the assay rests, the
whole may be lost on account of the glass being shattered. The
spirit-flame must be first applied to the fore part of the tube, and
then made to recede slowly until it fuses the assay. After the mixture
has been for some time kept in a molten state, the lamp must be
withdrawn, and the part containing the assay severed with a file. The
fore part of the tube must then be well washed, and afterwards dried
with bibulous paper. Should the fluorine contained in the substance be
appreciable, the glass tube, when held up to the light, will be found
to have lost its transparency, and to be very rough to the touch.
[3] Quoted by Plattner.
Great care should be observed not to allow this very corrosive acid to
come into contact with the skin, as an ulcer will be the consequence
that will be extremely difficult to heal.
When hydrofluoric acid comes in contact with any silicious substance,
hydrofluosilicic acid gas is always formed.
(12.) _Selenium_ (Se).--This element occurs in combination with lead
as the selenide, and with copper as the selenide of copper. It exists
also combined with cobalt and lead, as the selenide of these metals;
also as the selenide of lead and mercury.
The smallest trace of selenium may be detected by igniting a small
piece of charcoal in the flame of oxidation, when the peculiar and
unmistakable odor of decayed horse-radish will indicate the presence
of that element. An orange vapor is eliminated if the selenium be
present in any quantity, while there is an incrustation around the
assay of a grey color, with a metallic lustre. This incrustation
frequently presents a reddish-violet color at its exterior edges,
often running into a deep blue. If a substance containing selenium be
placed in a glass tube, closed at one end, and submitted to heat, the
selenium is sublimed, with an orange-colored vapor, and with the
characteristic odor of that substance. Upon the cool portions of the
tube a steel-grey sublimate is deposited, and, beyond that, can be
discerned small crystals of selenic acid. If the mineral be the
seleniferous lead glance, sulphurous acid gas will be given off, and
may be detected by the smell, or by a strip of moistened litmus paper.
If arsenic is present, heating upon charcoal will quickly lead to the
determination of the one from the other.
* * * * *
TABULAR STATEMENT OF THE REACTIONS OF MINERALS BEFORE THE BLOWPIPE.
In PART THIRD of this work, commencing at page 109, the student will
find a sufficiently explicit description of the blowpipe reactions of
those principal substances that would be likely to come beneath his
attention. The following tabular statement of those reactions--which
we take from Scheerer and Blanford's excellent little work upon the
blowpipe--will be of great benefit, as a vehicle for consultation,
when the want of time--or during the hurry of an examination--precludes
the attentive perusal of the more lengthy descriptions in the text.
In the examination of minerals, before the student avails himself of
the aid of the blowpipe, he should not neglect to examine the specimen
rigidly in relation to its physical characters, such as its hardness,
lustre, color, and peculiar crystallization. It is where the
difference of two minerals cannot be distinguished by their physical
appearance, that the aid of the blowpipe comes in most significantly
as an auxiliary. For instance, the two minerals molybdenite and
graphite resemble each other very closely, when examined in regard to
their physical appearance, but the blowpipe will quickly discriminate
them, for if a small piece of the former mineral be placed in the
flame of oxidation, a bright green color will be communicated to the
flame beyond it, while in the latter there will be no color. Thus, in
a very short time, these two minerals can be distinguished from each
other by aid of the blowpipe, while no amount of physical examination
could determine that point. The blowpipe is equally an indispensable
instrument in the determination of certain minerals which may exist in
others as essential or non-essential constituents of them. For
instance, should a minute quantity of manganese be present in a
mineral, it must be fused with twice its bulk of a mixture of two
parts of carbonate of soda, and one part of the nitrate of potassa, in
the flame of oxidation upon platinum foil. The manganate of soda thus
formed will color the fused mass of a bluish-green tint.
Or a slight quantity of arsenic may be discerned by the following
process recommended by Plattner:[4] one grain of the finely pulverized
metal is mixed with six grains of citrate of potassa, and slowly
heated on the platinum spoon. By this means the metals are oxidized,
while the arseniate of potassa is obtained. Then boil the fused mass
in a small quantity of water in a porcelain vessel till all tho
arseniate is dissolved. The metallic oxides are allowed to subside,
and the above solution decanted off into another porcelain vessel. A
few drops of sulphuric acid are added, and the solution boiled to
expel the nitric acid, after which it is evaporated to dryness. In
this operation, the sulphuric acid should be added only in sufficient
quantity to drive off the nitric acid, or, at the utmost, to form a
bisulphate with the excess of potassa. When dry, the salt thus
obtained is pulverized in an agate mortar, and mixed with about three
times its volume of oxalate of potassa, and a little charcoal powder.
The mixture is introduced into a glass bulb having a narrow neck, and
gently warmed over a spirit-lamp in order to drive off the moisture,
which must be absorbed by a piece of blotting-paper in the neck of the
bulb. After a short time, the temperature is increased to a low red
heat, at which the arsenious acid is reduced and the metallic arsenic
sublimed, and which re-condenses in the neck of the bulb. If there
the arsenic be so small in quantity as to exhibit no metallic lustre,
the neck of the bulb may be cut off with a file immediately above the
sublimate, and the latter exposed to the flame of the blowpipe, when
the arsenic is volatilized, and may be recognized by its garlic odor.
[4] Quoted by Scheerer.
If the presence of cadmium is suspected in zinc-blende, it may be
detected by fusing a small piece of the blende upon charcoal in
carbonate of soda. The peculiar bright yellow sublimate of the oxide
of cadmium, if it be present, will not fail to indicate it. This
incrustation can be easily distinguished from that of zinc. Thus, with
the three illustrations we have given, the student will readily
comprehend the great utility of the blowpipe in the examination of
minerals.
Although the following tables were not arranged especially for the
last part of this work, still this arrangement is so good that by
their consultation the student will readily comprehend at a glance
what requires some detail to explain, and we feel no hesitation in
saying that, although they are not very copious, they will not fail to
impart a vast amount of information, if consulted with any degree of
carefulness.
The minerals given are such as are best known to English and American
mineralogists under the names specified. For more detailed reactions
than could be crowded into a table, the student will have to consult
the particular substance as treated in Part Third. If this part is
perused carefully previous to consulting the tables, these will be
found eminently serviceable as a refresher of the memory, and may thus
save much time and trouble.
And, finally, we would certainly recommend the student, after he shall
have gone through our little volume (if he is ambitious of making
himself a thorough blowpipe analyst), to then take up the larger works
of Berzelius and Plattner, for our treatise pretends to nothing more
than a humble introduction to these more copious and scientific works.
* * * * *
Mineral. Diamond
Formula. C
Behavior
in glass-bulb. --
on platinum foil. In fine powder is slowly consumed without
residue in a strong oxidizing Flame.
* * * * *
Mineral. Graphite
Formula. C with some iron silica, etc.
Behavior
in glass-bulb. Generally gives off water.
on platinum foil. Is slowly consumed leaving more or less ash,
principally Fe^{2}O^{3}.
* * * * *
Mineral. Anthracite
Formula. C + x[.H]
Behavior
in glass-bulb. Evolves water.
on platinum foil. Is slowly consumed with the exception of a small
quantity of ash.
* * * * *
Mineral. Wallsend-coal
Formula. C, H, O, S and ash.
Behavior
in glass-bulb. Intumesces and gives off water and tarry matters
which partly condense in bulb, and leave a
porous coke.
on platinum foil. Takes fire under blowpipe flame, and burns with
a smoky flame, depositing much soot and leaving
a porous cinder which burns slowly and leaves a
small ash.
* * * * *
Mineral. Cannel-coal
Formula. C, H, N, O, S and ash.
Behavior
in glass-bulb. As the preceding but gives off more tar.
on platinum foil. Similar to the preceding. If held to the
lamp-flame, takes fire and burns for some
seconds.
* * * * *
Mineral. Brown-coal
Formula. C, H, N, O, S, and ash.
Behavior
in glass-bulb. Gives off much water and tar, and leaves a
porous cinder retaining the form of the original
fragment.
on platinum foil. Burns slowly and without flame, leaving some
ash.
* * * * *
Mineral. Asphaltum
Formula. C + H + O.
Behavior
in glass-bulb. Fuses with ease affording an empyreumatic oil
having an alkaline reaction, and combustible
gasses, and leaves a carbonaceous residue,
which is entirely consumed under the blowpipe
flame, except a little ash.
on platinum foil. Takes fire and burns with a bright flame and a
thick smoke.
* * * * *
Mineral. Elaterite
Formula. C + H.
Behavior
in glass-bulb. Fuses and gives off water having an acid
reaction, naphtha and a tarry fluid, which
chiefly condense in the neck of the bulb, and
leave a light, pulverulent carbonaceous residue.
on platinum foil. Fuses, takes fire, and burns with a smoky flame,
leaving a carbonaceous residue, which under the
blowpipe flame, is quickly consumed, with the
exception of the ashes.
* * * * *
Mineral. Hachettine
Formula. C + H.
Behavior
in glass-bulb. Fuses to a clear colorless liquid, which
solidifies on cooling and has a tallow-like
smell.
on platinum foil. Fuses, takes fire, and burns with a bright flame
until entirely consumed.
* * * * *
Mineral. Ozokerite
Formula. C + H.
Behavior
in glass-bulb. Fuses readily to a clear brown oily fluid, which
solidifies on cooling.
on platinum foil. As the preceding.
* * * * *
Mineral. Amber
Formula. C + H + O.
Behavior
in glass-bulb. Fuses with difficulty, and affords water, an
empyreumatic oil, and succinic acid which
condense in the neck of the bulb leaving a
shining black residue.
on platinum foil. Takes fire and burns with a yellow flame and a
peculiar aromatic odor.
* * * * *
Mineral. Mellite
Formula. [...Al][=M]^{3} + 15[.H]
Behavior
in glass-bulb. Gives off water. If heated to redness, is
carbonized, and gives a slight empyreumatic odor.
on platinum foil. On charcoal burns to a white ash, which moistened
with nitrate of cobalt and heated shows the
alumina reaction.
* * * * *
POTASH.
* * * * *
Mineral. Nitre
Formula. [.K][.....N]
Behavior
(1) in glass-bulb. Fuses readily to a clear liquid and with a
strong heat boils with the evolution of oxygen.
(2) in open tube. --
(3) on charcoal. Deflagrates leaving a saline mass, which is
absorbed into charcoal and gives a sulphur
reaction on silver.
(4) in forceps. On platinum wire fuses and colors the flame
violet more or less modified by lime and soda.
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. --
(8) Special reactions. With bisulphate of potassa in the glass-bulb
evolves nitrous fumes.
* * * * *
Mineral. Polyhalite
Formula. [.K][...S]+[.Mg][...S]+2[.Ca][...S]+2[.H]
Behavior
(1) in glass-bulb. Gives off water.
(2) in open tube. --
(3) on charcoal. Fuses to a reddish bead, which in the reducing
flame solidifies and shrinks to a hollow crust.
(4) in forceps. On platinum wire fuses and colors the flame
yellow from a small quantity of soda.
(5) in borax. Dissolves with ebullition to a clear glass,
which is slightly colored by iron, and when
saturated become opaque on cooling.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses. The alkalies are absorbed by the charcoal
leaving the lime and magnesia infusible on the
surface.
(8) Special reactions. The alkaline mass when laid on silver gives a
sulphur reaction.
* * * * *
SODA.
* * * * *
Mineral. Rock-salt
Formula. NaCl.
Behavior
(1) in glass-bulb. Fuses to a clear liquid
(2) in open tube. --
(3) on charcoal. Fuses, is absorbed by the charcoal and partially
volatilized incrusting the charcoal around.
(4) in forceps. Fuses with great ease and colors the flame
yellow.
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. --
(8) Special reactions. Gives the chlorine reactions.
* * * * *
Mineral. Natron
Formula. [.Na][..C] + 10[.H]
Behavior
(1) in glass-bulb. Fuses, with the evolution of water.
(2) in open tube. --
(3) on charcoal. Fuses, and is absorbed into the pores of the
charcoal.
(4) in forceps. Fuses and behaves as the preceding.
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. --
(8) Special reactions. Dissolves in acid with violent effervescence.
* * * * *
Mineral. Soda-nitre
Formula. [.Na][.....N].
Behavior
(1) in glass-bulb. Fuses and if strongly heated evolves nitrous
fumes.
(2) in open tube.
--
(3) on charcoal.
Deflagrates and is absorbed into the charcoal.
(4) in forceps. Deflagrates on platinum wire, coloring the flame
yellow.
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. --
(8) Special reactions. In a glass-bulb with bisulphate of potassa,
gives the NO^{5}-reaction.
* * * * *
Mineral. Glauber-salt
Formula. [.Na][...S] + 10[.H].
Behavior
(1) in glass-bulb. Fuses and gives off water having a neutral
reaction.
(2) in open tube. --
(3) on charcoal. Fuses, and is absorbed by the charcoal. The
saturated charcoal laid upon silver gives the
sulphur reaction
(4) in forceps. Fuses and colors the flame yellow.
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. --
(8) Special reactions. Gives the SO^{3}-reaction.
* * * * *
Mineral. Glauberite
Formula. [.Na][...S] + [.Ca][...S].
Behavior
(1) in glass-bulb. Decrepitates with the evolution of more or less
water, and when strongly heated fuses to a clear
liquid.
(2) in open tube. --
(3) on charcoal. Fuses to a clear bead, then spreads out; the
soda is absorbed and the lime left on the
surface. Laid on silver, the fused mass gives a
sulphur reaction.
(4) in forceps. Fuses easily to a clear glass, coloring the
flame yellow.
(5) in borax. Fuses easily and gives the lime reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. As alone in charcoal.
(8) Special reactions. As in preceding.
* * * * *
Mineral. Borax
Formula. [.Na][...B]^{2}+10[.H].
Behavior
(1) in glass-bulb. Intumesces with the evolution of water, and
under a strong heat fuses.
(2) in open tube. --
(3) on charcoal. Intumesces and fuses to a clear bead more or
less colored by impurities.
(4) in forceps. As on charcoal.
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. Fuses to a clear bead, which becomes crystalline
on cooling.
(8) Special reactions. Gives the boracic-acid-reaction.
* * * * *
Mineral. Cryolite
Formula. 3NaFl+Al^{2}Fl^{3}.
Behavior
(1) in glass-bulb. Decrepitates slightly and gives a trace of
water.
(2) in open tube. If heated so that the flame be allowed to play
up the tube upon the mineral, flourine is
evolved, which corrodes the interior of the
tube.
(3) on charcoal. Fuses to a limpid bead, which on cooling becomes
a white enamel. If heated for some time, it
bubbles, gives off fluorine and becomes
infusible.
(4) in forceps. Fuses, coloring the flame yellow.
(5) in borax. Dissolves to a clear bead, which is rendered
opaque by a large addition.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses to a clear bead, then spreads out on the
charcoal, the soda is absorbed, and an infusible
mass of alumina remains.
(8) Special reactions. If the alumina residue obtained be moistened
with cobalt solution and heated strongly, it
assumes a beautiful blue color.
* * * * *
BARYTA AND STRONTIA.
* * * * *
Mineral. Heavy-spar
Formula. [.Ba][...S].
Behavior
(1) in glass-bulb. Sometimes decrepitates and gives off more or
less water
(2) in open tube. --
(3) on charcoal. Fuses in the reducing flame.
(4) in forceps. Fuses with difficulty on edges. Colors the outer
flame green. In reducing flame forms BaS, which
fuses readily.
(5) in borax. Gives the baryta-reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses to a clear bead; then spreads out and is
absorbed into the charcoal. The fused mass laid
on silver gives the S-reaction.
(8) Special reactions. If fused with potassa on platinum, gives the
SO^{3}-reaction.
* * * * *
Mineral. Celestine
Formula. [.Sr][...S].
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. Fuses to a milk-white bead.
(4) in forceps. Colors the flame crimson.
(5) in borax. Gives the strontia-reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Similar to the preceding.
(8) Special reactions. Similar to the preceding.
* * * * *
Mineral. Witherite
Formula. [.Ba][..C].
Behavior
(1) in glass-bulb. Decrepitates more or less and evolves Water.
(2) in open tube. --
(3) on charcoal. Fuses, effervesces, and is partially absorbed by
the charcoal.
(4) in forceps. Colors the outer flame intensely green.
(5) in borax. Dissolves with effervescence and gives the
baryta-reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses to a clear bead; then spreads out and
passes into the charcoal.
(8) Special reactions. In dilute HCl dissolves with much effervescence.
* * * * *
Mineral. Strontianite
Formula. [.Sr][..C].
Behavior
(1) in glass-bulb. Becomes opaque.
(2) in open tube. --
(3) on charcoal. As in the forceps.
(4) in forceps. Exfoliates and becomes arborescent. The
filaments glow brilliantly and fuse on the
point. Colors the flame brilliantly crimson.
(5) in borax. Resembles the preceding.
(6) in mic. salt. As in borax.
(7) with carb. soda. As the preceding.
(8) Special reactions. As the preceding.
* * * * *
Mineral. Barytocalcite.
Formula. [.Ba][..C] + [.Ca][..C].
Behavior
(1) in glass-bulb. As in the preceding.
(2) in open tube. --
(3) on charcoal. In powder frits together, but does not fuse.
(4) in forceps. Colors the flame green in the centre and red
towards the point.
(5) in borax. Dissolves with effervescence. In large
quantities gives a semi-crystalline bead.
(6) in mic. salt. As in borax, but the saturated bead is
milk-white.
(7) with carb. soda. Fuses, and is partially absorbed leaving the
lime on the surface.
(8) Special reactions. As witherite.
* * * * *
LIME.
* * * * *
Mineral. Gypsum
Formula. [.Ca][...S] + 2[.H].
Behavior
(1) in glass-bulb. Turns white, giving off water and being
converted into plaster of Paris.
(2) in open tube. --
(3) on charcoal. In the reducing flame forms CaS, which has an
alkaline reaction on test paper, and gives a
sulphur-reaction when laid on silver and
moistened.
(4) in forceps. Fuses with difficulty to a bead, coloring the
flame red.
(5) in borax. Dissolves to a clear bead, which gives the lime-
reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Behaves as lime. The alkaline mass laid on
silver and moistened gives the sulphur-reaction.
(8) Special reactions. Gives the sulphuric-acid reaction.
* * * * *
Mineral. Apatite
{ Cl
Formula. [.Ca]{ -- +3[.Ca]^{3}[.....P]
{ Fl
Behavior
(1) in glass-bulb. Occasionally decrepitates and gives off some
water.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. IV. Previously dipped in SO^{3} colors the flame
green, afterwards red.
(5) in borax. Dissolves easily and when in some quantity gives
an opaline bead.
(6) in mic. salt. Gives the lime-reaction.
(7) with carb. soda. Is infusible. The alkali is absorbed, leaving
the lime on the on the surface of the charcoal.
(8) Special reactions. With microcosmic salt and oxide of copper, gives
the chlorine-reaction. With microcosmic salt in
the open tube evolves fluorine.
* * * * *
Mineral. Pharmacolite
Formula. [.Ca]^{2}[.....As] + 6[.H].
Behavior
(1) in glass-bulb. Gives off water, and emits an arsenical odor.
(2) in open tube. --
(3) on charcoal. Fuses to an opaque bead and emits a strong smell
of arsenic.
(4) in forceps. Fuses to a translucent violet colored bead, the
color being due to cobalt. Colors the flame blue
at first, then faintly red.
(5) in borax. Dissolves readily to a bead strongly colored by
cobalt, which obscures the lime-reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses, and emits As. The alkali is then absorbed
by the charcoal, as in the preceding.
(8) Special reactions. --
* * * * *
Mineral. Calespar
Formula. [.Ca][..C].
Behavior
(1) in glass-bulb. Turns white and sometimes decrepitates. Strongly
heated loses CO^{2} and becomes caustic.
(2) in open tube. --
(3) on charcoal. Turns white, or brown if containing much iron or
manganese and glows brilliantly.
(4) in forceps. Glows brilliantly, coloring the flame red.
Becomes caustic and shows a strong alkaline
reaction.
(5) in borax. Dissolves with evolution of CO^{2} and when pure
gives the lime-reaction. The bead is generally
more or less colored by iron and manganese.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses, and behaves as other lime-salts.
(8) Special reactions. Dissolves with effervescence in cold HCl.
* * * * *
Mineral. Fluorspar
Formula. CaFl
Behavior
(1) in glass-bulb. Phosphoresces with various colors, when heated
in the dark.
(2) in open tube. --
(3) on charcoal. Fuses easily to a clear bead, which becomes opaque
on cooling, then loses fluorine, glows brilliantly
and becomes infusible.
(4) in forceps. As on charcoal. Colors the flame red.
(5) in borax. Gives the lime-reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses to a clear bead, opaque on cooling. With
an addition of the alkali behaves as lime.
(8) Special reactions. With microcosmic salt in open tube gives the
fluorine-reaction.
* * * * *
MAGNESIA.
* * * * *
Mineral. Brucite
Formula. [.Mg][.H].
Behavior
(1) in glass-bulb. Evolves water.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V.
(5) in borax. Behaves as magnesia. Sometimes gives a faint
iron-reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Behaves as magnesia.
(8) Special reactions. With nitrate of cobalt, gives the magnesia
reaction
* * * * *
Mineral. Epsomite
Formula. [.Mg][...S] + 7[.H].
Behavior
(1) in glass-bulb. Evolves water having an acid reaction on test
paper.
(2) in open tube. --
(3) on charcoal. Gives of HO and SO^{3}, shines brilliantly, and
becomes alkaline and caustic.
(4) in forceps. V. As on charcoal.
(5) in borax. Behaves as magnesia.
(6) in mic. salt. As in borax.
(7) with carb. soda. The alkali is absorbed leaving the magnesia
on surface of the charcoal. Gives the
sulphur-reaction on silver.
(8) Special reactions. The magnesian residue obtained on treating with
carbonate of soda (7), assumes a flesh-tint,
when treated with cobalt.
* * * * *
Mineral. Boracite
Formula. [.Mg][...B]^{2} + 2[.Mg][...B].
Behavior
(1) in glass-bulb. Occasionally gives off a trace of water.
(2) in open tube. --
(3) on charcoal. Fuses with intumescence to a white crystalline
bead.
(4) in forceps. I. As on charcoal. Colors the flame green.
(5) in borax. Fuses easily to a clear bead, which is
crystalline, when containing much of the
mineral, and is usually slightly tinted by
iron.
(6) in mic. salt. As in borax.
(7) with carb. soda. With a small quantity of alkali fuses to a clear
bead on cooling. With a larger quantity gives a
clear, uncrystallizable bead.
(8) Special reactions. --
* * * * *
Mineral. Magnesite
Formula. [.Mg][..C].
Behavior
(1) in glass-bulb. Sometimes gives off a small quantity of water.
(2) in open tube. --
(3) on charcoal. Is infusible. With cobalt-solution, assumes a
dusky flesh tint.
(4) in forceps. --
(5) in borax. Behaves as magnesia. Sometimes a slight
iron-reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses to a bead, the soda is then absorbed,
leaving an infusable mass of magnesia.
(8) Special reactions. The magnesian residue obtained by fusing with
carbonate of soda gives the magnesian-reaction
with nitrate of cobalt. Dissolves with
effervescence in warm HCl.
* * * * *
Mineral. Mesitine spar
Formula. ([.Mg][.Fe][.Mn])[..C].
Behavior
(1) in glass-bulb. As magnesite.
(2) in open tube. --
(3) on charcoal. Is infusible. Assumes a deep brown color.
(4) in forceps. V.
(5) in borax. Gives the iron and manganese-reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. As magnesite, but the residual mass has a dark
color from iron and manganese.
(8) Special reactions. Dissolves with effervescense in warm HCl. With
carbonate of soda and nitre gives a
manganese-reaction.
* * * * *
ALUMINA.
* * * * *
Mineral. Sapphire
Corundum
Emery
Formula. [...Al=].
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V.
(5) in borax. In fine powder dissolves slowly to a colorless
glass.
(6) in mic. salt. As in borax.
(7) with carb. soda. --
(8) Special reactions. In fine powder moistened with cobalt-solution
and heated yields a blue color.
* * * * *
Mineral. Websterite
Formula. [...Al][...S] + 9[.H].
Behavior
(1) in glass-bulb. Gives off water, and, when heated to incipient
redness, sulphurous acid.
(2) in open tube. --
(3) on charcoal. Gives off water and SO^{3}, leaving an infusible
mass.
(4) in forceps. V.
(5) in borax. Behaves as alumina.
(6) in mic. salt. As in borax.
(7) with carb. soda. Yields an infusible mass, which laid on silver
and moistened, produces a black stain.
(8) Special reactions. Fused with potassa in platinum has no action on
silver. Cobalt-solution produces the alumina
reaction.
* * * * *
Mineral. Native Alum
Formula. [.R][...S] + [...Al][...S]^{3} + 24[.H].
Behavior
(1) in glass-bulb. Intumesces greatly and gives off much water.
Strongly heated, evolves SO^{3}, which reddens
litmus.
(2) in open tube. --
(3) on charcoal. Intumesces and become infusible.
(4) in forceps. V. Colors the flame violet if a potassa
alum--yellow if soda--be present.
(5) in borax. Dissolves and gives the iron and manganese
reaction, if these oxides be present. Otherwise
the bead is colorless.
(6) in mic. salt. As in borax.
(7) with carb. soda. The alkali is absorbed into the charcoal,
leaving an infusable mass which gives the sulfur
reaction on silver.
(8) Special reactions. If not containing too much iron or manganese
gives an alumina reaction with nitrate of of
cobalt. In other respects as the preceding.
* * * * *
Mineral. Turquoise
Formula. [...Al=]^{2}[.....P] + 5[.H].
Behavior
(1) in glass-bulb. Evolves water, occasionally decrepitates and
turns black.
(2) in open tube. --
(3) on charcoal. Turns brown, but remains infusible.
(4) in forceps. V. As on charcoal. Colors the outer flame green.
(5) in borax. In the oxidizing flame, gives a green bead, due
to copper and iron. In reducing flame, opaque red.
(6) in mic. salt. As in borax.
(7) with carb. soda. Intumesces, then fuses to a semi-clear glass
colored by iron. With more alkali yields an
infusible mass.
(8) Special reactions. Gives the phosphoric-acid reaction.
* * * * *
Mineral. Wavellite
Formula. [Al=]F^{3} + 3([...Al=]^{4}[.....P]^{3} + 18[.H].)
Behavior
(1) in glass-bulb. Evolves water and some fluorine, which attacks
the glass.
(2) in open tube. --
(3) on charcoal. Exfoliates and turns white.
(4) in forceps. V. As on charcoal. Colors the outer flame green,
especially if moistened with SO^{3}.
(5) in borax. As alumina. Generally gives also a slight iron
reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Forms an infusible white mass.
(8) Special reactions. With cobalt-solution on charcoal gives the
alumina reaction.
* * * * *
Mineral. Spinel
Formula. [.R][...Al=].
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V.
(5) in borax. Gives a slight iron reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses partially and forms a porous mass.
(8) Special reactions. With nitrate of cobalt gives the alumina
reaction. With nitre and carbonate of soda a
slight manganese reaction.
* * * * *
SILICATES.
The presence of silica in a mineral can easily be ascertained by
treating a small fragment in a bead of microcosmic salt. The bases
will dissolve out with more or less difficulty in the salt, and the
silica being insoluble will remain suspended in the bead, retaining
the original form of the fragment. In borax, the silicates of lime and
magnesia generally dissolve with considerable ease, but those of
alumina slowly and with difficulty. The silicates of lime are moreover
frequently characterized by intumescence or ebullition, when heated in
the forceps in the blowpipe flame. The minerals presenting this
character are marked in the table. As the most convenient mode of
classifying the silicates for blowpipe examination, the following
arrangement will be adopted:
TABLE I.--ANHYDROUS SILICATES.
TABLE II.--HYDROUS SILICATES.
FUSIBILITY.
I. Readily fusible to a bead.
II. With difficulty fusible to a bead.
III. Readily fusible on the edges.
IV. With difficulty fusible on the edges.
V. Infusible.
a. Afford a fluid bead with carbonate of soda.
b. Afford a fluid bead with but little of that salt, but with a
larger quantity a slaggy mass.
c. Afford a slaggy mass only.
This classification of minerals, according to their fusibility and
their behavior with carbonate of soda, was originally proposed by
_Berzelius_, and a table of the principal oxidized minerals arranged
according to these characters is given in his handbook of the
blowpipe, and thence adopted, with some alterations by _Plattner_, in
the very excellent and detailed work already many times cited. In the
following general table I., the more important silicates only are
included, and in table II. are enumerated in alphabetical order those
which afford characteristic reactions.
TABLE I.
Anhydrous Silicates.
________________________________________________________________________
Fus. alone and with NaC.
Mineral. Formula.
________________________________________________________________________
I.
a. Axinite ([.Ca][.Mg])^{3}([...B][...Si])^{3} +
([...Al=][...Fe=][...Mn=])^{2}([...Si][...B]) Int.
Elaolite ([.K][.Na])^{3}[...Si] + 3[...Al=][...Si] Int.
Garnet [.R]^{3}[...Si] + [.R=][...Si]
Oligoclase [.Na][...Si] + [...Al=][...Si]^{2}
Scapolite ([.Ca][.Na])^{3}[...Si]^{2} + 2[...Al=][...Si] Int.
Spodumene ([.Li][.Na])^{3}[...Si]^{2} + 4[...Al=][...Si]^{2}Int.
b. Asbestos As Hornblende
to II.
Augite ([.Ca][.Mg][.Fe][.Mn])^{3}[...Si]^{2} Int.
some var.
Epidote ([.Ca]Fe)^{3}[...Si] + Int.
to III. 2([...Al][...Fe][...Mn])[...Si]
Hornblende ([.Ca][.Mg][.Fe])^{4} + ([...Si][...Al=])^{3} Int.
some var.
Sodalite [.Na]^{3}[...Si] + 3[...Al=][...Si] + NaCl Int.
to III.
Vesuvian 3([.Ca][.Mg])^{3}[...Si] +
2([...Al=][...Fe=])[...Si] Int.
c. Biaxial Mica [.K][...Si] + 4([...Al=][...Fe=])[...Si]
to III.
Hauyne ([.K][.Na])^{3}[...Si] + 3[...Al=][...Si] +
[.Na][...Si]
Tourmaline ([.R][...R=][...B])^{4}[...Si]^{3} Int.
to V.
II.
a. Labradorite ([.Ca][.Na][.K])[...Si] +
([...Al=][...Fe=])[...Si]
Lepidolite (KNaL)F + ([...Al=][...Fe=])[...Si]^{2}?
Ryacolite [.K][...Si] + [...Al=][...Si]^{2}
Albite [.Na][...Si] + [...Al=][...Si]^{3}
b. Augite [.R]^{3}[...Si]^{2}
some var.
Actinolite ([.Ca][.Mg][.Fe])^{4}[...Si]^{3} Int.
Diopside ([.Ca][.Mg])^{3}[...Si]^{2} |
Humboltilite 2([.Ca][.Mg][.Na][.K])[...Si] +
([...Al=][...Fe=])[...Si]
Sahlite As Augite
Tremolite ([.Ca][.Mg])^{4}[...Si]^{3}
c. Pyrope ([.Ca][.Mg][.Fe])^{3}[...Si] + Al[...Si] +
m[...Cr]?
III.
a. Anorthite ([.Ca][.Mg][.Na][.K])^{3}[...Si] +
3([...Al=][...Fe=])[...Si]
Nepheline ([.Na][.K][.Ca])^{2}[...Si] + 2[...Al=][...Si]
Obsidian [...Si],[...Al=],[...Fe=],[.Fe],[.Ca][.Na][.K] Int.
Orthoclase ([.K][.Na])[...Si] + [...Al=][...Si]^{3}
Petalite ([.Li][.Na])^{3}[...Si]^{4} + 4[...Al=][...Si]^{4}
Pumice [...Si],[...Al=],[.Ca],[.K],[.Na],[.H] Int.
b. Gadolinite ([.Y][.Ce][.La][.Fe][.Ca])^{3}[...Si]
to V.
Nephrite ([.Ca][.Mg][.Fe])^{4}[...Si]^{3}? Int.
Wollastonite [.Ca]^{3}[...Si]^{2} |
c. Iolite ([.Mg][.Fe])^{3}[...Si]^{2} + 3[...Al=][...Si]
IV.
a. Beryl [...Be][...Si]^{2} + [...Al=][...Si]^{2}
b. Diallage ([.Ca][.Mg][.Fe])^{3}([...Si][...Al=])^{2}
Hypersthene ([.Mg][.Fe])^{3}[...Si]^{2} |
c. Fuchsite ([.K]^{5}[...Si])^{2} +
9([...Al=][...Cr=])^{6}[...Si]^{6}
V.
a. Leucite [.K]^{3}[...Si]^{2} + [...Al=][...Si]^{2}
b. Chondrodite ([.Mg],[.Mg]F)^{4}([...Si]SiF^{3})
Olivine ([.Mg][.Fe][.Ca])^{2}[...Si]
c. Andalusite ([...Al=]Fe)^{3}[...Si]^{2}
Chrysoberyl [...Be] + [...Al=]
Kaynite [...Al=]^{3}[...Si]^{2}
Pycnite 6[...Al=]^{3}[...Si]^{2} + (3[...Al=]F^{3} +
2[...Si]F^{3})
Topaz 6[...Al=]^{3}[...Si]^{2} + (3[...Al=]F^{3} +
2[...Si]F^{3})
Zircon [...Zr=][...Si]
Staurolite ([...Al=]Fe)^{2}[...Si]
________________________________________________________________________
Hydrous Silicates.
________________________________________________________________________
Fus. alone and with NaC.
Mineral. Formula.
________________________________________________________________________
I.
a. Analcime [.Na]^{3}[...Si]^{2} + 3[...Al=][...Si]^{2}
+ 6[.H] Int.
Apophyllite ([.K], KF)([...Si], SiF^{3}) + 6[.Ca][...Si] +
15[.H] Int.
Brewsterite ([.Sr][.Ba])[...Si] + [...Al=][...Si]^{3} + 5[.H] Int.
Chabasite ([.Ca],[.Na],[.K])^{3}[...Si] +
3[...Al=][...Si]^{2} + 18[.H] Int.
Lapis Lazuli [...Si],[...S],[...Al=], Fe, [.Ca], [.Na], [.H]
Laumonite [.Ca]^{3}[...Si]^{2} + 3[...Al=][...Si]^{2}
+ 12[.H] Int.
Mesotype ([.Na][.Ca])[...Si] + [...Al=][...Si] + 3[.H] Int.
Natrolite [.Na][...Si] + [...Al=][...Si] + 2[.H] Int.
Prehnite [.Ca]^{2}[...Si] + [...Al=][...Si] + [.H] Int.
Scolezite [.Ca][...Si] + [...Al=][...Si] + 3[.H] Int.
Thomsonite ([.Ca][.Na])^{3}[...Si] + 3[...Al=][...Si]
+ 7[.H] Int.
Datholite 2[.Ca]^{3}[...Si] + [...B]^{3}[...Si]^{2} + 3[.H] Int.
Heulandite [.Ca][...Si] + [...Al=][...Si]^{3} + 5[.H] Int.
Stilbite [.Ca][...Si] + [...Al=][...Si]^{3} + 6[.H] Int.
b. Okenite [.Ca]^{3}[...Si]^{4} + 6[.H] Int.
Pectolite ([.Ca][.Na])^{4}[...Si]^{3} + [.H] Int.
c. Saponite 2[.Mg]^{3}[...Si]^{2} + [...Al=][...Si]
+ 10 or 6[.H]
II.
a. Antrimolite 3([.Ca][.K])[...Si] + 5[...Al=][...Si] +
15[.H]
Harmatome [...Ba][...Si] + [...Al=]S^{2} + 5[.H]
b. Brevicite [.Na][...Si] + [...Al=][...Si] + 2[.H]
Orthite [.R]^{3}[...Si] + [...R=][...Si] + ([.H]?) Int.
III.
c. Pitchstone [...Si],[...Al=], Fe, [.Mg][.Na], [.K][.H]
Talc to V. [.Mg]^{6}[...Si]^{5} + 2[.H]
Chlorite 3([.Mg]Fe)^{3}[...Si] + ([...Al=]Fe)^{2}[...Si]
+ 9[.H]
Pinite [...Si],[...Al=],[.Fe],[.K],[.Mg],[.H]
IV.
a. Steatite [.Mg]^{6}[...Si]^{5} + 4[.H]
c. Gilbertite [...Si],[...Al=],[.Fe],[.Mg],[.H] Int.
Meerschaum [.Mg][...Si] + [.H] |
Serpentine [.Mg]^{9}[...Si]^{4} + 6[.H] |
V.
a. Gismondine ([.Ca][.K])^{2}[...Si] + 2[...Al=][...Si] + 9[.H]
________________________________________________________________________
TABLE II.
_______________________________________________________________________
|
Analcime | If transparent becomes white and opaque when heated,
| but on incipient fusion resumes its transparency and
| then fuses to a clear glass.
|
Andalusite | When powdered and treated with cobalt solution on
| charcoal, assumes a blue color.
|
Apophyllite | Fuses to a frothy white glass.
|
Axinite | Imparts a green color to the blowpipe flame, owing to
| the presence of boracic acid. This reaction is
| especially distinct, if the mineral be previously mixed
| with fluorspar and bisulphate of potassa.
|
Beryl | Sometimes gives a chromium reaction in borax and
| microcosmic salt.
|
Chabasite | Fuses to a white enamel.
|
Chondrodite | Evolves fluorine in the glass tube, both when heated
| alone and with microcosmic salt. It sometimes also
| gives off a trace of water.
|
Chrysoberyl | Is unattacked by carbonate of soda. With nitrate of
| cobalt on charcoal the finely powdered mineral
| assumes a blue color.
|
Datholite | Fuses to a clear glass and colors the flame green.
|
Diallage | Frequently gives off water in small quantity.
|
Fuchsite | Gives the chromium reaction with borax and microcosmic
| salt.
|
Gadolinite | That from Hitteroe, if heated in a partially covered
| platinum spoon to low redness, glows suddenly and
| brilliantly.
|
Hauyne | Affords the sulphur reaction both on charcoal and when
| fused with potassa. It contains both sulphur and
| sulphuric acid.
|
Hypersthene | As Diallage.
|
Kyanite | As Andalusite.
|
Lapis Lazuli | Fuses to a white glass, and when treated with carbonate
| of soda on charcoal, gives the sulphur reaction on
| silver.
|
Laumonite | When strongly heated, exfoliates and curls up.
|
Lepidolite | Colors the blowpipe flame crimson, from lithia; also
| gives the fluorine reaction with microcosmic salt.
|
Leucite | Some varieties, when treated with cobalt solution,
| assume a blue color.
|
Meerschaum | In the glass bulb frequently blackens and evolves an
| empyreumatic odor due to organic matter. When this is
| burnt off, it again becomes white, and if moistened
| with nitrate of cobalt solution and heated, assumes
| a pink color.
|
Okenite | Behaves as Apophyllite.
|
Olivine | Some varieties give off fluorine, when fused with
| microcosmic salt.
|
Pectolite | Similar to Apophyllite.
|
Petalite | Imparts a slight crimson color to the flame, like
| Lepidolite.
|
Prehnite | As Chabasite.
|
Pycnite | Assumes a blue color, when treated with nitrate of
| cobalt. Gives the fluorine reaction with microcosmic
| salt.
|
Pyrope | Gives the chromium reaction with borax and microcosmic
| salt.
|
Scolecite | Similar to Laumonite, but more marked.
|
Scapolite | Occasionally contains a small quantity of lithia, and
| colors the flame red when fused with fluorspar and
| bisulphate of potassa.
|
Sodalite | If mixed with one-fifth its volume of oxide of copper,
| moistened to make the mixture cohere, and a small
| portion placed upon charcoal and heated with the blue
| oxidizing flame, the outer flame will be colored
| intensely blue from chloride of copper.
|
|
Spodumene | When not too strongly heated, colors the blowpipe
| flame red, when more strongly, yellow.
|
Stilbite | As Chabasite.
|
Topaz | When heated, remains clear. Otherwise as Pycnite.
|
Tourmaline | Gives the boracic acid reaction with flourspar and
| bisulphate of potassa.
|
Wollastonite | Colors the blowpipe flame faintly red from lime.
|
Zircon | The colored varieties become white or colorless and
| transparent, when heated. Is only slightly attacked
| by carbonate of soda.
______________|________________________________________________________
* * * * *
URANIUM.
* * * * *
Mineral. Pitchblende
Formula. [.U][...U=] essentially.
Behavior
(1) in glass-bulb. Evolves some water and a small quantity of
sulphur, sulphide of arsenic and metallic
arsenic.
(2) in open tube. Evolves SO^{2} and a white sublimate of
arsenious acid.
(3) on charcoal. Gives off arsenical fumes.
(4) in forceps. III. Colors the flame blue beyond the assay,
owing to the presence of Pb. Sometimes also
green towards the point, due to Cu.
(5) in borax. The roasted mineral affords the uranium
reaction.
(6) in mic. salt. As borax. Also a small residue of silica.
(7) with carb. soda. Infusible. Affords the characteristic Pb
incrustation, and sometimes yields minute
particles of Cu.
(8) Special reactions. --
* * * * *
Mineral. Uranium ochre
Formula.
[...U=][.H]^{2}.
Behavior
(1) in glass-bulb. Evolves water and assumes a red color.
(2) in open tube. --
(3) on charcoal. V. In reducing flame assumes a green color.
(4) in forceps. --
(5) in borax. Gives the uranium reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. --
(8) Special reactions. --
* * * * *
Mineral. Uranite
Formula. ([.Ca] +[...U=]^{2})[.....]P + 8[.H].
Behavior
(1) in glass-bulb. Evolves water and becomes yellow and opaque.
(2) in open tube. --
(3) on charcoal. Fuses with intumescence to a black bead having a
semi-crystalline surface.
(4) in forceps. --
(5) in borax. Gives the uranium reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Forms an infusible yellow slag.
(8) Special reactions. Gives the PO^{5} reaction.
* * * * *
Mineral. Chalcolite
Formula. ([.Cu]+[...U=]^{2})[.....P] + 8[.H].
Behavior
(1) in glass-bulb. As uranite.
(2) in open tube. --
(3) on charcoal. As uranite.
(4) in forceps. As uranite.
(5) in borax. In the oxidizing flame gives a green bead, which
in the reducing flame becomes of an opaque red,
from Cu.
(6) in mic. salt. As in borax.
(7) with carb. soda. In reducing flame yields a metallic bead of Cu.
(8) Special reactions. As uranite.
* * * * *
IRON.
* * * * *
Mineral. Iron pyrites
Formula. FeS^{2}.
Behavior
(1) in glass-bulb. Gives a considerable yellow sublimate of
sulphur, and sometimes sulphide of arsenic. Also
HS.
(2) in open tube. Sulphurous acid and sometimes arsenious acid are
evolved.
(3) on charcoal. Gives off some sulphur, which burns with a blue
flame. Residue fuses to a magnetic bead.
(4) in forceps. --
(5) in borax. The roasted mineral gives a strong iron
reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses to a black mass, which spreads out on
charcoal and gives the sulphur reaction on
silver.
(8) Special reactions. --
* * * * *
Mineral. Magnetic pyrites
Formula.
[,Fe]^{5}[,,,Fe=].
Behavior
(1) in glass-bulb. --
(2) in open tube. Evolves sulphurous acid.
(3) on charcoal. Fuses to a magnetic bead black on the surface,
and with a yellow shining fracture.
(4) in forceps. --
(5) in borax. As iron pyrites.
(6) in mic. salt. As in borax.
(7) with carb. soda. As iron pyrites.
(8) Special reactions. --
* * * * *
Mineral. Mispickel
Formula. FeAs + FeS^{2}.
Behavior
(1) in glass-bulb. A red sublimate of AsS^{2} is first formed and
then a black sublimate of metallic arsenic.
(2) in open tube. Sulphurous and arsenious acids are evolved, the
latter forming a white sublimate.
(3) on charcoal. Gives off much arsenic forming a white
incrustation and fuses to a magnetic globule.
(4) in forceps. --
(5) in borax. As iron pyrites.
(6) in mic. salt. As in borax.
(7) with carb. soda. As iron pyrites.
(8) Special reactions. --
* * * * *
Mineral. Magnetic iron ore
Formula. Fe^{3}O^{4}
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. In the blue flame, fuses on edges and remains
magnetic.
(5) in borax. Gives the iron reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. --
(8) Special reactions. --
* * * * *
Mineral. Specular iron
Red haematite
Formula. Fe^{2}O^{3}
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V. In the blue flame is converted into
Fe^{2}O^{4}, and then behaves as the preceding.
(5) in borax. As magnetic iron ore.
(6) in mic. salt. As in borax.
(7) with carb. soda. --
(8) Special reactions. --
* * * * *
Mineral. Göthite
Formula. [...Fe][.H].
Behavior
(1) in glass-bulb. Evolves water.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. As specular iron.
(5) in borax. As specular iron.
(6) in mic. salt. As in borax.
(7) with carb. soda. --
(8) Special reactions. --
* * * * *
Mineral. Franklinite
Formula. ([.Fe][.Zn][.Mn]) ([...Fe=][...Mn=]).
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. Forms a white incrustation on the charcoal,
which moistened with cobalt solution assumes a
green color.
(4) in forceps. V. In the blue flame fuses on edges and and
becomes magnetic.
(5) in borax. Gives the iron and manganese reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Affords a considerable white incrustation of
ZnO.
(8) Special reactions. Gives a strong manganese reaction with nitre and
carbonate of soda.
* * * * *
Mineral. Ilmenite
Formula. [...Ti=] and [...Fe=].
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V. In reducing flame fuses on edges and becomes
magnetic.
(5) in borax. Gives the iron reaction.
(6) in mic. salt. In oxidizing flame exhibits the iron reaction.
In reducing flame assumes a deep brownish red
color.
(7) with carb. soda. --
(8) Special reactions. --
* * * * *
Mineral. Chromic iron
Formula. [.Fe][...Cr=].
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. As the preceding.
(5) in borax. Dissolves slowly and gives the chromium
reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. On platinum foil with nitre and carbonate of
soda affords a yellow mass of chromate of
potassa.
(8) Special reactions. --
* * * * *
Mineral. Lievrite
Formula. 3([.Fe][.Ca])^{3}[...Si] + 2[...Fe=][...Si].
Behavior
(1) in glass-bulb. Occasionally gives off some water and turns
black.
(2) in open tube. --
(3) on charcoal. Fuses to a black globule, which in the reducing
flame becomes magnetic.
(4) in forceps. I. In reducing flame is magnetic.
(5) in borax. Gives the iron reaction.
(6) in mic. salt. Gives the iron and silica reactions.
(7) with carb. soda. Fuses to a black opaque bead.
(8) Special reactions. Generally gives the manganese reaction with
nitre and carbonate of soda.
* * * * *
Mineral. Chloropal
Formula. [...Fe=][...Si]^{2} + 3[.H].
Behavior
(1) in glass-bulb. Decrepitates more or less, gives off much water
and turns black.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V. Loses color and turns black.
(5) in borax. Gives the iron reaction.
(6) in mic. salt. Gives the iron and silica reaction.
(7) with carb. soda. Fuses to a transparent green glass.
(8) Special reactions. --
* * * * *
Mineral. Green earth
Formula. [...Si],[.Fe],[...Al=],[.Na],[.K],[.H], etc.
Behavior
(1) in glass-bulb. Gives off water and becomes darker in color.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V. In reducing flame fuses on edges and colors
the outer flame yellow ([.Na]) or violet ([.K]).
(5) in borax. As the preceding.
(6) in mic. salt. As the preceding.
(7) with carb. soda. Forms a slaggy mass.
(8) Special reactions. --
* * * * *
Mineral. Siderite
Formula. [.Fe][..C].
Behavior
(1) in glass-bulb. Occasionally decrepitates. Gives off CO^{2} and
turns black and magnetic.
(2) in open tube. --
(3) on charcoal. As in glass bulb.
(4) in forceps. Behaves similarly to the magnetic oxide.
(5) in borax. Gives the iron and manganese reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Behaves as an oxide. With nitre and carbonate of
soda on platinum generally gives the manganese
reaction.
(8) Special reactions. In acid dissolves with effervescense.
* * * * *
Mineral. Copperas
Formula. [.Fe][...S] + 7[.H].
Behavior
(1) in glass-bulb. Gives off water, and, when strongly heated,
SO^{2} and SO^{3}, which reddens litmus paper.
(2) in open tube. Evolves water and SO^{2}, which may be
recognized by its odor.
(3) on charcoal. Loses water and SO^{2}, and is converted into
[...Fe=].
(4) in forceps. Gives off H and SO^{2}, and then behaves as the
magnetic oxide.
(5) in borax. The roasted mineral affords an iron reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Forms sulphide of sodium and oxide of iron. The
former is absorbed into the charcoal, and if cut
out and laid upon silver and moistened gives the
S reaction.
(8) Special reactions. If dissolved in water, and a strip of
silver-foil be introduced into the solution, the
metal remains untarnished.
* * * * *
Mineral. Vivianite
Formula. [.Fe]^{3}[.....P] + 8[.H].
Behavior
(1) in glass-bulb. Gives off water.
(2) in open tube. --
(3) on charcoal. Froths up and then fuses to a grey metallic
bead.
(4) in forceps. As on charcoal. Singes flame green ([.....P]).
(5) in borax. Gives the iron reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. In reducing flame becomes magnetic and fuses to
a black saggy mass.
(8) Special reactions. --
* * * * *
Mineral. Iriphyline
Formula. ([.Fe][.Mn][.Li])^{3}[.....P].
Behavior
(1) in glass-bulb. Gives off water, having an alkaline reaction,
and assumes a metallic lustre resembling
graphite.
(2) in open tube. --
(3) on charcoal. Fuses readily to a black magnetic bead with a
metallic lustre.
(4) in forceps. I. On platinum wire colors the flame crimson
([.Li]) and green ([.....P]), towards the point
fuses to a black magnetic bead.
(5) in borax. Gives the iron and manganese reactions.
(6) in mic. salt. Gives the iron reaction which overpowers that of
the manganese.
(7) with carb. soda. Forms an infusible porous mass, which under
the reducing flame becomes magnetic.
(8) Special reactions. Gives the manganese reaction with nitre and
carbonate of soda on platinum foil.
* * * * *
Mineral. Scorodite
Formula. [...Fe=][.....As] + 4[.H].
Behavior
(1) in glass-bulb. Evolves water.
(2) in open tube. Gives off water and AsO^{3}.
(3) on charcoal. Emits arsenical fume and in the reducing flame
fuses to a magnetic mass having a metallic
lustre.
(4) in forceps. I. As on charcoal. Colors the outer flame
blue.
(5) in borax. The roasted mineral gives an iron reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. As alone on charcoal.
(8) Special reactions. Gives the arsenic reactions.
* * * * *
Mineral. Cube ore
Formula. [.Fe]^{3}[.....As] +
[...Fe=]^{3}[.....As]^{2} + 18[.H].
Behavior
(1) in glass-bulb. Evolves much water.
(2) in open tube. As the preceding.
(3) on charcoal. As the preceding.
(4) in forceps. As the preceding.
(5) in borax. As the preceding.
(6) in mic. salt. As in borax.
(7) with carb. soda. As the preceding.
(8) Special reactions. As the preceding.
* * * * *
MANGANESE.
* * * * *
Mineral. Manganblende
Formula. MnS.
Behavior
(1) in glass-bulb. --
(2) in open tube. Gives off SO^{2} and becomes greyish green on
surface.
(3) on charcoal. Is slowly roasted and converted into oxide.
(4) in forceps. V.
(5) in borax. The roasted mineral gives a strong manganese
reaction.
(6) in mic. salt. In the unroasted state, dissolves with much
ebullition and detonation due to elimination of
sulphide of phosphorus. The bead then exhibits
the characteristic violet color of manganese.
(7) with carb. soda. Forms a slaggy mass, which laid on silver and
moistened, gives the sulphur reaction.
(8) Special reactions. --
* * * * *
Mineral. Pyrolusite
Formula. [..Mn].
Behavior
(1) in glass-bulb. Frequently gives off a small quantity of water
and, when strongly heated, oxygen.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V.
(5) in borax. Gives the manganese reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Forms a slaggy mass.
(8) Special reactions. --
* * * * *
Mineral. Manganite
Formula. [...Mn=][.H].
Behavior
(1) in glass-bulb. Gives off much water.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V. Exfoliates slightly.
(5) in borax. As the preceding.
(6) in mic. salt. As in borax.
(7) with carb. soda. As the preceding.
(8) Special reactions. --
* * * * *
Mineral. Psilomelane
Formula. ([.Ba],[.Ca],[.Mg],[.K]) [..Mn] + [.H].
Behavior
(1) in glass-bulb. Gives off water and, when
strongly heated, oxygen.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V. Colors flame faintly green(Ba) and red
towards the point (Ca).
(5) in borax. As pyrolusite.
(6) in mic. salt. As in borax.
(7) with carb. soda. As pyrolusite.
(8) Special reactions. --
* * * * *
Mineral. Wad
Formula. [..Mn],[.Mn],[.H], also [...Fe=],[...Al=],
[.Ba],[.Cu],[...Pb],[...Si], etc.
Behavior
(1) in glass-bulb. Gives off water.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V. Colors flame variously according to its
composition.
(5) in borax. Gives the manganese reaction, more or less
modified by the presence of other oxides.
(6) in mic. salt. As in borax.
(7) with carb. soda. As pyrolusite.
(8) Special reactions. Various according to composition. When strongly
heated and then moistened has an alkaline
reaction on red litmus paper.
* * * * *
Mineral. Rhodonite
Formula. [.Mn]^{3}[...Si]^{2}.
Behavior
(1) in glass-bulb. Gives off more or less water.
(2) in open tube. --
(3) on charcoal. Under a strong flame fuses to a brown opaque
bead.
(4) in forceps. II. As on charcoal.
(5) in borax. In the oxidizing flame gives the manganese
reaction. In reducing flame the iron reaction.
(6) in mic. salt. As in borax, but leaves an insoluble siliceous
skeleton.
(7) with carb. soda. With a small quantity of the alkali fuses to a
black bead. With a larger quantity forms a slag.
(8) Special reactions. --
* * * * *
Mineral. Diallogite
Formula. [.Mn][..C].
Behavior
(1) in glass-bulb. Frequently decrepitates and gives off more or
less water.
(2) in open tube. --
(3) on charcoal. If strongly heated and moistened has an alkaline
reaction on litmus paper due to the presence of
Ca.
(4) in forceps. V. Frequently colors the flame slightly red.
(5) in borax. Gives the manganese and iron reactions.
(6) in mic. salt. As in borax.
(7) with carb. soda. Forms an infusible slag.
(8) Special reactions. In warm acid dissolves with much effervescence.
* * * * *
Mineral. Triplite
Formula. ([..Mn][.Fe])^{4}[.....P].
Behavior
(1) in glass-bulb. Generally gives off more or less
water.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. I. Colors the outer blowpipe flame green
([.....P]).
(5) in borax. Gives the manganese and iron reactions.
(6) in mic. salt. As in borax.
(7) with carb. soda. Forms an infusible mass.
(8) Special reactions. --
* * * * *
NICKEL AND COBALT.
* * * * *
Mineral. Millerite
Formula. NiS.
Behavior
(1) in glass-bulb. --
(2) in open tube. Evolves SO^{2}.
(3) on charcoal. Fuses with much ebullition to a magnetic bead.
(4) in forceps. --
(5) in borax. The roasted mineral gives a nickel reaction,
slightly modified by small quantities of iron
and copper.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses to a slaggy mass, which on silver gives
the sulphur reaction.
(8) Special reactions. --
* * * * *
Mineral. Coppernickel
Formula. Ni^{2}As.
Behavior
(1) in glass-bulb. Gives off a little AsO^{3}.
(2) in open tube. Gives off much AsO^{3} and some SO^{2} and falls
to powder.
(3) on charcoal. Fuses to a magnetic bead, with the evolution of
arsenic, which colors the flame blue.
(4) in forceps. --
(5) in borax. The arsenical bead obtained by fusing the
mineral on charcoal, if fused upon the same
support with borax successively added and
removed, gives firstly an iron reaction, then
cobalt if present, and lastly nickel.
(6) in mic. salt. If the residual bead which has been treated with
borax be further treated with microcosmic salt,
the nickel reaction will be obtained and
sometimes a slight copper reaction.
(7) with carb. soda. --
(8) Special reactions. Affords a sublimate of metallic arsenic when
treated with cyanide of potassium.
* * * * *
Mineral. Smaltine
Formula. CoAs.
Behavior
(1) in glass-bulb. When strongly heated generally evolves metallic
arsenic.
(2) in open tube. Gives a crystalline sublimate of AsO^{3}. Also
some SO^{2}.
(3) on charcoal. Gives off fumes of arsenic, and fuses to a dark
grey magnetic bead, very brittle, colors flame
blue.
(4) in forceps. --
(5) in borax. As the preceding, but the cobalt being in large
excess requires some time for its perfect
oxidation, before the nickel reaction is
exhibited.
(6) in mic. salt. Gives the cobalt reaction, and after the cobalt
has been, removed that of nickel.
(7) with carb. soda. --
(8) Special reactions. As the preceding.
* * * * *
Mineral. Glance cobalt
Formula. CoS^{2} + CoAs.
Behavior
(1) in glass-bulb. --
(2) in open tube. As the preceding, but gives off more SO^{2}.
(3) on charcoal. Gives off S and As, and fuses to a magnetic
bead. Colors flame blue.
(4) in forceps. --
(5) in borax. Gives a cobalt and slight iron reaction when
treated as the preceding minerals.
(6) in mic. salt. As in borax.
(7) with carb. soda. Gives a sulphur reaction of silver.
(8) Special reactions. As the preceding.
* * * * *
Mineral. Nickel glance
Formula. NiS^{2} + NiAs.
Behavior
(1) in glass-bulb. Decrepitates and gives an orange colored
sublimate of AsS^{2}.
(2) in open tube. As the preceding.
(3) on charcoal. As the preceding.
(4) in forceps. --
(5) in borax. As copper nickel.
(6) in mic. salt. Gives the nickel reaction occasionally somewhat
obscured by cobalt.
(7) with carb. soda. As the preceding.
(8) Special reactions. As copper nickel.
* * * * *
Mineral. Ulmannite
Formula. NiS^{2} + Ni(AsSb)^{2}.
Behavior
(1) in glass-bulb. Gives a slight white sublimate of SbO^{3} and
more or less AsS^{3}.
(2) in open tube. Gives off thick fumes of SbO^{3} and SbO^{5}
with AsO^{3} and SO^{2}.
(3) on charcoal. As glance cobalt, but accompanied by dense fumes
of SbO^{3}.
(4) in forceps. --
(5) in borax. As copper nickel.
(6) in mic. salt. As the preceding.
(7) with carb. soda. As the preceding.
(8) Special reactions. As copper nickel generally, but arsenic is not
always present.
* * * * *
Mineral. Cobalt pyrites
Formula. ([,Co][,Ni][,Fe]) ([,,,Co=][,,,Ni=][,,,Fe=]).
Behavior
(1) in glass-bulb. When strongly heated gives off sulphur and
becomes brown.
(2) in open tube. Gives off much SO^{2} and a small quantity of
AsO^{3}.
(3) on charcoal. In the reducing flame small fragments fuse with
the evolution of sulphur to a magnetic bead
having a bronze colored fracture.
(4) in forceps. --
(5) in borax. In the oxidizing flame on charcoal gives a
violet colored glass. In the reducing flame the
nickel is reduced and may collected in a gold
bead. When the nickel is removed, the glass
exhibits a slight iron reaction while warm.
(6) in mic. salt. As in borax, but the reduction of the nickel is
more difficult than in the latter flux.
(7) with carb. soda. As glance cobalt.
(8) Special reactions. As copper nickel, but the amount of arsenic is
usually very small.
* * * * *
Mineral. Emerald nickel
Formula. [.Ni]^{3}[..C] + 6[.H].
Behavior
(1) in glass-bulb. Gives off much water and turns black.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. --
(5) in borax. Dissolves with much effervescence and gives the
nickel reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Forms a slaggy mass.
(8) Special reactions. In warm dilute HCl dissolves with much
effervescence.
* * * * *
Mineral. Cobalt Bloom
Formula. [.Co]^{3}[.....As] + 8[.H].
Behavior
(1) in glass-bulb. Gives off water.
(2) in open tube. --
(3) on charcoal. Evolves arsenical fumes and in the reducing
flame fuses to a dark grey bead of arsenide of
cobalt.
(4) in forceps. In the point of the blue flame fuses and colors
the outer flame blue (As).
(5) in borax. Gives the cobalt reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. --
(8) Special reactions. Gives off arsenic with cyanide of potassium in
glass tube.
* * * * *
Mineral. Earthy cobalt
Formula. [.Mn],[.Co],[.Cu],[.Fe],[.H], etc.
Behavior
(1) in glass-bulb. Gives off water.
(2) in open tube. --
(3) on charcoal. Emits a slight smell of arsenic, but does not
fuse.
(4) in forceps. Colors the flame blue.
(5) in borax. In oxidizing flame gives the cobalt reaction
which obscures those of [.Mn], [.Cu], etc. In
reducing flame occasionally gives the [.Cu]
reaction.
(6) in mic. salt. As in borax. If a saturated bead be treated on
charcoal with tin in the reducing flame for a
few seconds, the [.Cu] reaction is sometimes
obtained.
(7) with carb. soda. Forms an infusible mass.
(8) Special reactions. With carbonate of soda and nitre on platinum
foil, gives a strong manganese reaction.
* * * * *
ZINC.
* * * * *
Mineral. Zincblende
Formula. ZnS.
Behavior
(1) in glass-bulb. Decrepitates strongly.
(2) in open tube. Evolves SO and becomes white or yellow if
containing iron.
(3) on charcoal. V. In the reducing flame incrusts the charcoal
with ZnO; also with CdO, if that metal be
present.
(4) in forceps. --
(5) in borax. The roasted mineral gives a zinc reaction, and
sometimes a slight iron reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. As alone on charcoal. Moreover colors the flame
blue. The fused alkali gives a S reaction on
silver.
(8) Special reactions. --
* * * * *
Mineral. Red oxide of zinc
Formula. [.Zn].
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. In the reducing flame forms a thin incrustation
of oxide of zinc on the charcoal.
(4) in forceps. V.
(5) in borax. Generally gives a manganese and slight iron
reaction in addition to that of zinc.
(6) in mic. salt. As in borax.
(7) with carb. soda. On charcoal, forms a thick incrustation of ZnO.
(8) Special reactions. With carbonate of soda and nitre on platinum
foil gives manganese reaction.
* * * * *
Mineral. Electric calamine
Formula. 2[.Zn]^{3}[...Si] + 3[.H]
Behavior
(1) in glass-bulb. Gives off water and becomes white and opaque.
(2) in open tube. --
(3) on charcoal. --
(4) in forceps. V.
(5) in borax. Dissolves to a clear glass, which cannot be
rendered opaque by the intermittent flame.
(6) in mic. salt. Dissolves to a clear glass, which becomes opaque
on cooling. Silica remains insoluble.
(7) with carb. soda. With carbonate of soda alone is infusible. With
2 parts of alkali and 1 of borax fuses to a
glass and sets free [.Zn], which incrusts the
charcoal.
(8) Special reactions. --
* * * * *
Mineral. Calamine
Formula. [.Zn][..C].
Behavior
(1) in glass-bulb. Gives off CO^{2} and becomes opaque.
(2) in open tube. --
(3) on charcoal. As the red oxide. Sometimes also gives a lead
incrustation.
(4) in forceps. V.
(5) in borax. Gives a zinc reaction and frequently an iron and
manganese reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Forms a thick incrustation of zinc, sometimes
also of [.Pb] and [.Co].
(8) Special reactions. Dissolves with much effervescence in cold acid.
* * * * *
BISMUTH.
* * * * *
Mineral. Native bismuth
Formula. Bi.
Behavior
(1) in glass-bulb. --
(2) in open tube. Fuses and is converted into a yellow oxide.
(3) on charcoal. Fuses to a bead and incrusts the charcoal with
oxide.
(4) in forceps. --
(5) in borax. The oxide formed upon charcoal gives the bismuth
reactions.
(6) in mic. salt. As in borax.
(7) with carb. soda. --
(8) Special reactions. --
* * * * *
Mineral. Bismuthine
Formula. BiS.
Behavior
(1) in glass-bulb. --
(2) in open tube. Fuses with ebullition and gives of S and SO^{2}.
(3) on charcoal. Fuses with much spirting and in the reducing
flame yields a metallic bead and incrusts the
charcoal with oxide.
(4) in forceps. --
(5) in borax. The oxide obtained upon charcoal gives the
bismuth reactions.
(6) in mic. salt. As in borax.
(7) with carb. soda. As alone on charcoal. The fused alkali gives the
sulphur reaction on silver.
(8) Special reactions. --
* * * * *
Mineral. Bismuthblende
Formula. [...Bi=]^{2}[...Si]^{3}.
Behavior
(1) in glass-bulb. Turns yellow and, when strongly heated, fuses.
(2) in open tube. --
(3) on charcoal. Fuses with ebullition to a brown globule forming
an incrustation of [...Bi=] on the charcoal.
(4) in forceps. I. Fuses with ease to a yellow bead, coloring
the outer flame bluish green, especially if
moistened with HCl. This color is due to
[.....P].
(5) in borax. Gives the bismuth and also an iron reaction.
(6) in mic. salt. As in borax, but leaves a silicious skeleton.
(7) with carb. soda. Fuses to a yellow mass. The bismuth is then
reduced to the metallic state and partially
volatilized, incrusting the charcoal beyond.
(8) Special reactions. --
* * * * *
Mineral. Tetradymite
Formula. Bi, Te, S.
Behavior
(1) in glass-bulb. Occasionally decrepitates and then fuses,
forming a greyish white sublimate immediately
above the mineral fragment.
(2) in open tube. Fuses and gives off white fumes, part of which
pass up the tube and part deposit immediately
above the mineral. This latter if heated fuses
to clear drops (TeO^{3}). The mineral residue
becomes surrounded by fused [...Bi=],
characterized by its yellow color.
(3) on charcoal. Fuses to a metallic bead, colors the outer flame
bluish green (Te and Se) and incrusts the
charcoal around with the orange [...Bi=], beyond
which is a white incrustation partly consisting
of [...Te].
(4) in forceps. --
(5) in borax. The yellow oxide obtained upon charcoal gives
the bismuth reaction, and the white incrustation
of bismuth and telluric acid.
(6) in mic. salt. As in borax.
(7) with carb. soda. In the reducing flame yields a bead of metallic
bismuth, part of which is part of the tellurium
volatilized and incrusts the charcoal around.
(8) Special reactions. The fused alkaline mass gives the sulphur
reaction on silver. Also gives the tellurium
reaction with charcoal and carbonate of soda.
* * * * *
LEAD.
* * * * *
Mineral. Galena
Formula. PbS.
Behavior
(1) in glass-bulb. Generally decrepitates and gives off a small
quantity of sulphur.
(2) in open tube. Gives off SO^{2}, and when strongly heated, a
white sublimate of [.Pb], [.S].
(3) on charcoal. Fuses and is reduced affording a bead of
metallic lead, and forming an incrustation of
PbO on the charcoal. Colors the outer flame
blue.
(4) in forceps. --
(5) in borax. The oxide formed upon charcoal gives the lead
reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. As alone on charcoal. The fused alkali gives a
sulphur reaction on silver.
(8) Special reactions. --
* * * * *
Mineral. Clausthalite
Formula. PbSe.
Behavior
(1) in glass-bulb. Decrepitates slightly.
(2) in open tube. Forms a sublimate of selenium, which is grey
when thickly deposited, and red when thin.
(3) on charcoal. Gives off fumes smelling strongly of selenium
and coloring the flame blue. In the reducing
flame fuses partially and incrusts the charcoal
with Se and PbO. After some time a black
infusible mass alone remains.
(4) in forceps. --
(5) in borax. The infusible residue obtained upon charcoal
gives an iron and sometimes copper and cobalt
reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. With carbonate of soda, oxalate of potash yields
a metallic bead, the fused alkali laid upon
silver and moistened produces a stain similar to
that produced by sulfur.
(8) Special reactions. --
* * * * *
Mineral. Jamesonite
Formula. [,Pb]^{3}[,,,Sb]^{2}.
Behavior
(1) in glass-bulb. Fuses and gives off some sulphur, sulphide of
antimony and antimony which condense in the neck
of the bulb.
(2) in open tube. Fuses and emits dense white fumes of SbO^{3},
which pass off and redden blue litmus paper.
(3) on charcoal. Fuses with great ease evolving much SbO^{3} and
PbO, which incrusts the charcoal around the
mineral. When the fumes have ceased, a small
bead of metallic lead remains.
(4) in forceps. --
(5) in borax. The yellow incrustation formed upon charcoal
gives the reaction of lead, and the white those
of antimony.
(6) in mic. salt. As in borax.
(7) with carb. soda. As alone on charcoal. The fused alkali gives the
sulphur reaction on silver.
(8) Special reactions. --
* * * * *
Mineral. Minium
Formula. Pb^{3}O^{4}.
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. Is reduced first to litharge (PbO) and then to
metallic lead which forms the usual
incrustation.
(4) in forceps. Colors the outer flame blue.
(5) in borax. Gives the lead reactions.
(6) in mic. salt. As in borax.
(7) with carb. soda. As alone on charcoal.
(8) Special reactions. --
* * * * *
Mineral. Mendipite
Formula. PbCl + 2PbO.
Behavior
(1) in glass-bulb. Decrepitates slightly and assumes a yellow
color.
(2) in open tube. --
(3) on charcoal. Fuses readily and is reduced to metallic lead
with the evolution of acid fumes. Forms a white
incrustation of PbCl, and a yellow one of PbO.
(4) in forceps. As the preceding.
(5) in borax. As the preceding.
(6) in mic. salt. As in borax.
(7) with carb. soda. As alone on charcoal.
(8) Special reactions. Gives the chlorine reaction with CuO and
microcosmic salt.
* * * * *
Mineral. Cerusite
Formula. [.Pb][..C].
Behavior
(1) in glass-bulb. Decrepitates, gives off CO^{2}, turns yellow and
fuses.
(2) in open tube. --
(3) on charcoal. Is reduced to metallic lead, incrusting the
charcoal around with PbO.
(4) in forceps. As the preceding.
(5) in borax. Gives the lead reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. As alone on charcoal.
(8) Special reactions. In nitric acid dissolves with much
effervescence.
* * * * *
Mineral. Anglesite
Formula. [.Pb][...S].
Behavior
(1) in glass-bulb. Decrepitates and gives off a small quantity of
water.
(2) in open tube. --
(3) on charcoal. In the oxidizing flame fuses to a clear bead,
which becomes opaque on cooling. In reducing
flame is reduced with much ebullition to a
metallic bead and incrusts the charcoal around
with PbO.
(4) in forceps. As the preceding.
(5) in borax. Gives the lead reaction and occasionally a
slight iron and manganese reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Is reduced yielding a metallic lead bead. The
fused alkaline mass gives a sulphur reaction on
silver.
(8) Special reactions. --
* * * * *
Mineral. Pyromorphite
Formula. PbCl + 3[.Pb]^{3}[.....P].
Behavior
(1) in glass-bulb. Decrepitates, and when strongly heated for some
time, gives a slight white sublimate of PbCl.
(2) in open tube. --
(3) on charcoal. In oxidizing flame fuses to a bead having a
crystalline surface on cooling, and forms a thin
film of PbCl on the charcoal In reducing flame
fuses without reduction and on cooling assumes a
polyhedral form. Incrusts the charcoal slightly
with PbO.
(4) in forceps. Fuses and colors the flame blue.
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. Is reduced yielding a metallic bead and
incrusting the charcoal with PbO.
(8) Special reactions. Gives the chlorine reaction with microcosmic
salt and CuO. Also the phosphoric acid
reactions.
* * * * *
Mineral. Mimetene
Formula. PbCl+ 3[.Pb]^{3}[.....As]
Behavior
(1) in glass-bulb. As the preceding.
(2) in open tube. --
(3) on charcoal. Fuses, but less easily than the preceding, gives
off AsO^{3} and incrusts the charcoal with
PbCl. Finally is reduced to a metallic bead and
forms an incrustation of PbO.
(4) in forceps. As the preceding.
(5) in borax. The oxide formed on charcoal gives the lead
reactions.
(6) in mic. salt. As in borax.
(7) with carb. soda. As the preceding.
(8) Special reactions. Gives the chlorine reaction.
* * * * *
Mineral. Vanadinite
Formula. PbCl + 3[.Pb]^{3}[...V]?
Behavior
(1) in glass-bulb. As pyromorphite.
(2) in open tube. --
(3) on charcoal. The powdered mineral fuses fuses to a black
shining mass, which in the reducing flame
affords a metallic bead. Incrusts the charcoal
first with a white film of PbCl and afterwards
with PbO.
(4) in forceps. As pyromorphite.
(5) in borax. Dissolves readily to a clear glass, which, in
the oxidizing flame, is yellow, while hot, and
colorless when cold. In reducing flame becomes
opaque, and on cooling green.
(6) in mic. salt. In oxidizing flame is yellow while hot, becoming
paler on cooling. In reducing flame brown while
warm, and emerald green when cold.
(7) with carb. soda. On platinum wire fuses to a yellow bead, which
is crystalline on cooling. On charcoal yields a
button of metallic lead.
(8) Special reactions. With microcosmic salt and CuO, gives the chlorine
reaction. If fused in a platinum spoon with from
3 to 4 times its volume of [.K],[...S]^{2} it
forms a fluid yellow mass having an orange color
when cold.
* * * * *
Mineral. Crocoisite
Formula. [.Pb][...Cr].
Behavior
(1) in glass-bulb. Decrepitates violently and assumes a dark color.
(2) in open tube. --
(3) on charcoal. Fuses and detonates yielding Cr^{2}O^{3} and
metallic lead, and forming an incrustation of
PbO on the charcoal.
(4) in forceps. As pyromorphite.
(5) in borax. Dissolves readily and colors the glass yellow
while warm, and green when cold. (See Chromium
reaction.)
(6) in mic. salt. As in borax.
(7) with carb. soda. On platinum foil gives a dark yellow mass, which
becomes paler on cooling. On charcoal yields a
metallic button.
(8) Special reactions. Treated as above with [.K],[...S]^{2} forms a
violet colored mass, which on solidifying
becomes reddish and on cooling pale grey.
* * * * *
Mineral. Molybdate of lead
Formula. [.Pb][...M].
Behavior
(1) in glass-bulb. As the preceding.
(2) in open tube. --
(3) on charcoal. Fuses and is partly absorbed into the charcoal
leaving a globule of metallic lead, which is
partially oxidized and incrusts the charcoal.
(4) in forceps. As pyromorphite.
(5) in borax. Dissolves readily and gives the molybdena
reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Yields metallic lead.
(8) Special reactions. Fused as above with [.K],[...S]^{2} forms a yellow mass,
which becomes white on cooling. If this be
dissolved in water and a piece of zinc
introduced into the solution, the latter becomes
blue.
* * * * *
Mineral. Scheeletine
Formula. [.Pb][...W].
Behavior
(1) in glass-bulb. Decrepitates more or less.
(2) in open tube. --
(3) on charcoal. Fuses to a bead incrusting the charcoal with
PbO. The bead on cooling is crystalline and has
a dark metallic surface.
(4) in forceps. As pyromorphite.
(5) in borax. Dissolves to a clear colorless glass, which in
the reducing flame becomes yellow, and on
cooling grey and opaque.
(6) in mic. salt. Dissolves to a clear colorless glass, which
in the reducing flame assumes a dusky blue
color. After a time becomes opaque.
(7) with carb. soda. As the preceding.
(8) Special reactions. With carbonate of soda and nitre gives the
manganese reaction.
* * * * *
COPPER.
* * * * *
Mineral. Native Copper
Formula. Cu.
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. Fuses to a brilliant metallic bead, which on
cooling becomes covered with a coating of black
oxide.
(4) in forceps. Fuses and colors the outer flame blue.
(5) in borax. In the oxidizing flame dissolves and then gives
the copper reactions.
(6) in mic. salt. As in borax.
(7) with carb. soda. --
(8) Special reactions. --
* * * * *
Mineral. Vitreous Copper
Formula. Cu^{2}S.
Behavior
(1) in glass-bulb. --
(2) in open tube. Evolves SO^{2} and, when pulverized and gently
heated for some time is converted into CuO.
(3) on charcoal. Fuses to a bead, which spirts considerably and
gives off SO^{2}. When pulverized and gently
roasted, is converted into CuO.
(4) in forceps. --
(5) in borax. The roasted mineral gives the copper reaction,
and sometimes also a slight iron-reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. In the reducing flame is decomposed, forming NaS
and metallic copper. If the former be cut out
and laid upon silver, it gives the sulfur
reaction.
(8) Special reactions. --
* * * * *
Mineral. Copper pyrites
Formula. [,Cu=][,,,Fe=].
Behavior
(1) in glass-bulb. Decrepitates, sometimes gives a sublimate of
sulphur and becomes bronze colored on the
surface.
(2) in open tube. Evolves SO^{2} and is finally converted into a
dark red mixture of Fe^{2}O^{3} and CuO.
(3) on charcoal. Fuses readily with much ebullition and is
magnetic on cooling.
(4) in forceps. --
(5) in borax. As the preceding; but when the copper has been
removed by reducing on charcoal, the bead shows
a strong iron color.
(6) in mic. salt. As the preceding, but the color in the oxidizing
flame is green, owing to the presence of iron.
(7) with carb. soda. Yields a bead of metallic copper and some
magnetic oxide of iron which remains on the
charcoal. The fused gives a sulphur reaction on
silver.
(8) Special reactions. --
* * * * *
Mineral. Fahlerz
Formula. ([,Cu=][,Ag][,Fe][,Zn])^{4} ([,,,Sb][,,,As]).
Behavior
(1) in glass-bulb. Sometimes decrepitates, fuses, and when very
strongly heated, gives a red sublimate of
[,,,Sb] with [...Sb], also sometimes a black
sublimate of [,Hg] and occasionally [,,,As].
(2) in open tube. Fuses and gives off thick fumes of SbO^{3} and
SO^{2}, also generally AsO^{3}, leaving a black
infusible residue. If Hg be present, it is
sublimed and condenses in the tube in small
drops.
(3) on charcoal. Fuses to a bead, which fumes strongly and
incrusts the charcoal with SbO^{3}, and
sometimes ZnO, which cannot be volatilized.
Emits a strong smell of arsenic.
(4) in forceps. --
(5) in borax. The residue obtained on charcoal thoroughly
roasted gives a copper reaction, and when the
latter has been removed by reduction upon
charcoal, an iron reaction.
(6) in mic. salt. As in the preceding.
(7) with carb. soda. With this flux and a little borax yields a bead
of metallic copper; on silver, the alkaline mass
gives a sulphur reaction.
(8) Special reactions. If the copper bead obtained by fusing upon
carbonate of soda be cupelled with assay lead, a
silver bead will be obtained. Or if dissolved in
nitric acid and a drop or two of HCl added, a
white precipitate of AgCl will be formed, which
may be collected and reduced with carbonate of
soda upon charcoal.
* * * * *
Mineral. Tennatite
Formula. ([,Cu=][,Fe=])^{4}[,,,As].
Behavior
(1) in glass-bulb. Decrepitates occasionally and gives a red
sublimate of [,,,As].
(2) in open tube. Evolves [..S] and [...As], which condense and
form a white sublimate.
(3) on charcoal. Fuses to a magnetic bead giving of arsenical and
sulphurous fumes.
(4) in forceps. --
(5) in borax. As the preceding.
(6) in mic. salt. As the preceding.
(7) with carb. soda. Yields a copper bead and metallic iron in the
form of a dark grey powder. The fused alkali
gives the sulphur reaction.
(8) Special reactions. --
* * * * *
Mineral. Bournonite
Formula. ([,Pb]^{2}[,Cu=])[,,,Sb].
Behavior
(1) in glass-bulb. Decrepitates giving off sulfur and, when
strongly heated, [,,,Sb] and [...Sb].
(2) in open tube. Evolves thick white fumes of [...Sb],[.....Sb]
and [.Pb][...Sb]. Also [.S].
(3) on charcoal. Fuses readily and incrusts the charcoal with
[...Sb] and [.Pb] leaving a dark colored bead.
(4) in forceps. --
(5) in borax. If the bead obtained on charcoal be fused on
that support in the reducing flame with borax, a
slight iron reaction is obtained, and after a
time a copper reaction.
(6) in mic. salt. As with borax.
(7) with carb. soda. Yields a bead of metallic copper and lead and
incrusts the charcoal with [...Sb] and [.Pb].
The alkaline mass laid on silver and moistened
gives the sulphur reaction.
(8) Special reactions. --
* * * * *
Mineral. Red oxide of copper
Formula. Cu^{2}O
Behavior
(1) in glass-bulb. --
(2) in open tube. Is converted into the black oxide CuO.
(3) on charcoal. In the reducing flame is reduced, forming a
bead of metallic copper.
(4) in forceps. Fuses and colors the the flame emerald
green, or if previously moistened with HCl,
blue.
(5) in borax. Gives the copper reaction.
(6) in mic. salt. As with borax.
(7) with carb. soda. Is reduced to a bead of metallic copper.
(8) Special reactions. --
* * * * *
Mineral. Atacamite
Formula. CuCl + 3[.Cu] + 6[.H].
Behavior
(1) in glass-bulb. Gives off much water, having an acid
reaction, on test paper, and forms a light
grey sublimate of CuCl.
(2) in open tube. --
(3) on charcoal. Fuses, colors the flame blue, forms a brown
and a pale grey incrustation on the
charcoal, and is reduced to metallic copper,
leaving a small quantity of slag.
(4) in forceps. Fuses and colors the outer flame intensely
blue and green towards the point.
(5) in borax. Gives the copper reactions.
(6) in mic. salt. As with borax.
(7) with carb. soda. Is reduced, yielding a bead of metallic
copper.
(8) Special reactions. --
* * * * *
Mineral. Dioptase
Formula. [.Cu]^{3}[...Si]^{2} + 3[.H].
Behavior
(1) in glass-bulb. Gives off water and turns black.
(2) in open tube. --
(3) on charcoal. In the oxidizing flame becomes black. In the
reducing flame red.
(4) in forceps. V. Colors the outer flame intensely green.
(5) in borax. Gives the copper reactions.
(6) in mic. salt. As with borax. The silica remains
undissolved.
(7) with carb. soda. With a small quantity of carbonate of soda
fuses to a bead, which on cooling is opaque
and has a red fracture. With more alkali
forms a slag, containing little beads of
reduced copper.
(8) Special reactions. --
* * * * *
Mineral. Malachite
Formula. [.Cu]^{2}[..C] + [.H].
Behavior
(1) in glass-bulb. Gives off water and turns black.
(2) in open tube. --
(3) on charcoal. Fuses to a bead with a strong flame is
reduced to metallic copper.
(4) in forceps. Fuses and colors the outer flame brilliantly
green.
(5) in borax. Gives the copper reaction.
(6) in mic. salt. As with borax.
(7) with carb. soda. Yields metallic copper.
(8) Special reactions. Dissolves in HCl with much effervescence.
* * * * *
Mineral. Blue vitriol
Formula. [.Cu][...S] + 5[.H].
Behavior
(1) in glass-bulb. Intumesces, gives off water and becomes
white.
(2) in open tube. Strongly heated is decomposed, given off
SO^{2} and being converted into CuO.
(3) on charcoal. As in the glass-bulb. Then fuses, coloring
the outer flame green, and is reduced to
metallic copper and [,Cu=].
(4) in forceps. Fuses and colors the outer flame blue.
(5) in borax. The roasted mineral gives copper reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Yields metallic copper. The alkaline mass
laid on silver gives S reaction.
(8) Special reactions. Gives the sulphuric acid reaction.
* * * * *
Mineral. Libethenite
Formula. [.Cu]^{4}[.....P] + 2[.H].
Behavior
(1) in glass-bulb. Gives off water and turns black.
(2) in open tube. --
(3) on charcoal. Gradually heated, turns black and fuses to a
bead, having a core of metallic copper.
(4) in forceps. Fuses but does not color the flame
distinctly. On cooling is black and
crystalline.
(5) in borax. Gives the copper reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. With much of the alkali is decomposed,
yielding metallic copper. With small
portions successively added first fuses and
then intumesces, fuses with a strong flame,
and is then absorbed into the charcoal,
leaving metallic copper.
(8) Special reactions. Gives the phosphoric acid reaction.
* * * * *
Mineral. Olivenite
Formula. [.Cu]^{4}([.....As][.....P]) + [.H].
Behavior
(1) in glass-bulb. Gives off water.
(2) in open tube. --
(3) on charcoal. Fuses with detonation and the evolution of
arsenical fumes to a brittle regulus, brown
externally and having a white fracture.
(4) in forceps. Fuses and colors the outer flame green. On
cooling has a crystalline surface.
(5) in borax. Gives the copper reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. Is reduced, yielding metallic copper.
(8) Special reactions. Gives the arsenic reactions.
* * * * *
ANTIMONY.
* * * * *
Mineral. Native antimony
Formula. Sb.
Behavior
(1) in glass-bulb. Fuses and, when strongly heated, volatilizes
being redeposited in the tube as a dark grey
sublimate.
(2) in open tube. Fuses and gives off dense white fumes, which
are partly redeposited on the tube.
Sometimes also gives off arsenical fumes in
small quantity.
(3) on charcoal. Fuses and gives off dense white fumes, which
thickly incrust the charcoal and color the
flame blue immediately beyond the assay.
(4) in forceps. --
(5) in borax. The oxide formed upon charcoal gives the
antimony reactions.
(6) in mic. salt. As in borax.
(7) with carb. soda. --
(8) Special reactions. The incrustation on the charcoal, if treated
with nitrate of cobalt assumes the
characteristic green color.
* * * * *
Mineral. Grey antimony
Formula. SbS^{3}.
Behavior
(1) in glass-bulb. Fuses readily and occasionally gives off a
small quantity of sulphur. Strongly heated
forms a brown sublimate of SbS^{3} and
SbO^{3}.
(2) in open tube. Fuses and gives off SO^{2}, which passes off
up the tube, and dense white fumes of
SbO^{3} and SbO^{5} which are partly
deposited in the tube.
(3) on charcoal. Fuses and is partly absorbed by the charcoal
and partly volatilized, incrusting the
charcoal with the characteristic white
oxides. Colors the flame blue.
(4) in forceps. --
(5) in borax. As the preceding.
(6) in mic. salt. As in borax.
(7) with carb. soda. Fuses and is reduced, yielding metallic
antimony, which behaves as the preceding
mineral upon charcoal. The alkaline mass
gives the sulphur reaction.
(8) Special reactions. As the preceding.
* * * * *
Mineral. Antimony blende
Formula. [,,,Sb]^{2} + [...Sb].
Behavior
(1) in glass-bulb. Fuses easily, gives off first SbO^{3} and
afterwards an orange colored sublimate.
Strongly heated, is decomposed and gives a
black sublimate, which becomes brown on
cooling.
(2) in open tube. As the preceding.
(3) on charcoal. As the preceding.
(4) in forceps. --
(5) in borax. As native antimony.
(6) in mic. salt. As in borax.
(7) with carb. soda. As the preceding.
(8) Special reactions. As native antimony.
* * * * *
Mineral. White antimony
Formula. SbO^{3}.
Behavior
(1) in glass-bulb. Is sublimed and recondensed in the neck of
the tube.
(2) in open tube. As in the glass-bulb.
(3) on charcoal. Fuses with the evolution of dense white
fumes, which incrust the surface of the
charcoal. In the reducing flame is partly
reduced, yielding metallic antimony. Colors
flame blue.
(4) in forceps. Fuses and is volatilized, coloring the outer
flame blue.
(5) in borax. Gives the antimony reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. In the reducing flame is reduced, yielding
metallic antimony.
(8) Special reactions. As native antimony.
* * * * *
ARSENIC.
* * * * *
Mineral. Native arsenic
Formula. As.
Behavior
(1) in glass-bulb. Sublimes without fusion and recondenses as a
dark grey metallic sublimate, sometimes
leaving a small residue.
(2) in open tube. If gently heated in a good current of air
passes off as AsO^{3}, which is partly
condensed as a white sublimate in the upper
part of the tube.
(3) on charcoal. Passes off as AsO^{3}, which thinly incrusts
the charcoal beyond the assay.
(4) in forceps. Colors the flame blue.
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. --
(8) Special reactions. --
* * * * *
Mineral. Realgar
Formula. AsS^{2}.
Behavior
(1) in glass-bulb. Fuses, enters into ebullition and is
sublimed as a transparent red sublimate.
(2) in open tube. Gently heated passes off as SO^{2} and
AsO^{3}, the latter of which is redeposited
in the upper part of the tube.
(3) on charcoal. Fuses and passes off as arsenious and
sulphurous acids.
(4) in forceps. Fuses and colors the flame blue.
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. As on charcoal, except that the S combines
with the alkali forming NaS, which on silver
gives the sulphur reaction.
(8) Special reactions. --
* * * * *
Mineral. Orpiment
Formula. AsS^{3}.
Behavior
(1) in glass-bulb. As the preceding, except that the sublimate
is of a dark yellow color when cold.
(2) in open tube. As the preceding.
(3) on charcoal. As the preceding.
(4) in forceps. As the preceding.
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. As the preceding.
(8) Special reactions. --
* * * * *
Mineral. White arsenic
Formula. AsO^{3}.
Behavior
(1) in glass-bulb. Sublimes without fusion and re-condenses in
white crystals.
(2) in open tube. --
(3) on charcoal. Sublimes and is partly recondensed on
charcoal forming a white incrustation.
(4) in forceps. Colors the flame blue.
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. --
(8) Special reactions. Heated with charcoal in a glass-tube sealed
at one end, is reduced and metallic arsenic
sublimes.
* * * * *
MERCURY.
* * * * *
Mineral. Native mercury
Formula. Hg.
Behavior
(1) in glass-bulb. Volatilizes with little or no residue and
recondenses in neck of bulb.
(2) in open tube. --
(3) on charcoal. Is volatilized.
(4) in forceps. --
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. --
(8) Special reactions. --
* * * * *
Mineral. Cinnabar
Formula. HgS.
Behavior
(1) in glass-bulb. Volatilizes sometimes leaving a slight
earthy residue, and re-condenses as a black
sulphide.
(2) in open tube. If gently heated is decomposed into metallic
mercury, which volatilizes and recondenses
in the upper part of the tube, and SO^{2},
which passes off as is easily recognized by
its odor and bleaching properties.
(3) on charcoal. Is volatilized, generally leaving a small
earthy residue.
(4) in forceps. --
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. With carbonate of soda and cyanide of
potassium is decomposed and metallic mercury
volatilized.
(8) Special reactions. When in the preceding experiment the mercury
has been entirely dissipated, the alkaline
residue laid on silver gives a sulphur
reaction.
* * * * *
Mineral. Native amalgam
Formula. AgHg^{2}.
Behavior
(1) in glass-bulb. As native mercury, but leaves a residue of
pure silver.
(2) in open tube. --
(3) on charcoal. The mercury volatilizes leaving the silver,
which fuses to a bead, and, in the oxidizing
flame, incrusts the charcoal with its
characteristic oxide.
(4) in forceps. --
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. --
(8) Special reactions. --
* * * * *
SILVER.
* * * * *
Mineral. Native silver
Formula. Ag.
Behavior
(1) in glass-bulb. --
(2) in open tube. --
(3) on charcoal. Fuses and in a strong oxidizing flame forms
an incrustation of dark brown oxide on the
charcoal. If any antimony be present, it
affords a crimson incrustation.
(4) in forceps. --
(5) in borax. Gives the silver reactions.
(6) in mic. salt. As in borax.
(7) with carb. soda. --
(8) Special reactions. --
* * * * *
Mineral. Antimonial silver
Formula. Ag^{2}Sb.
Behavior
(1) in glass-bulb. --
(2) in open tube. Gives off dense white fumes, which are
partly deposited in the tube.
(3) on charcoal. Fuses, fumes strongly, forming a white
incrustation, and when the antimony is
nearly expelled a crimson one, a nearly pure
silver bead remains.
(4) in forceps. --
(5) in borax. The incrustation formed on charcoal gives an
antimony reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. As alone on charcoal.
(8) Special reactions. --
* * * * *
Mineral. Silver glance
Formula. AgS.
Behavior
(1) in glass-bulb. --
(2) in open tube. Gives off sulphurous acid.
(3) on charcoal. Gives off SO^{2} and is reduced to metallic
silver. If impure, a small quantity of slag
also remains.
(4) in forceps. --
(5) in borax. The residual slag (if any) obtained upon
charcoal gives an iron reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. As alone on charcoal. The alkaline mass gives
a sulphur reaction on polished silver.
(8) Special reactions. --
* * * * *
Mineral. Stephanite
Formula. [,Ag]^{6}[,,,Sb].
Behavior
(1) in glass-bulb. Decrepitates, fuses and gives a slight
sublimate of sulphide of antimony.
(2) in open tube. Fuses and gives off SO^{2} and dense white
antimonial fumes.
(3) on charcoal. Fuses and incrusts the charcoal with
antimonious acid, leaving Ag with some
antimony. If the flame be continued, a red
incrustation is formed and finally a bead of
pure silver remains surrounded by a small
slag.
(4) in forceps. --
(5) in borax. The residual slag obtained on the charcoal
gives an iron and copper reaction.
(6) in mic. salt. As in borax.
(7) with carb. soda. The silver is reduced and the antimony
passes off in dense fumes. The fused alkali
gives the sulphur reaction on silver.
(8) Special reactions. --
* * * * *
Mineral. Pyargyrite
Formula. [,Ag]^{3}[,,,Sb].
Behavior
(1) in glass-bulb. Sometimes decrepitates, fuses readily, and,
when strongly heated, gives a red sublimate
of SbS^{3}.
(2) in open tube. As in the preceding.
(3) on charcoal. Fuses with much spirting and covers the
charcoal with antimonial fumes. When the
residual AgS is heated for some time in the
oxidizing flame, a bead of pure silver is
obtained.
(4) in forceps. --
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. As the preceding.
(8) Special reactions. --
* * * * *
Mineral. Proustite
Formula. [,Ag]^{3}[,,,As].
Behavior
(1) in glass-bulb. Fuses and at a low red heat affords a small
sublimate of AsS^{3}.
(2) in open tube. Gradually heated it gives off AsO^{3} and
SO^{2}. Sometimes also antimony fumes.
(3) on charcoal. As the preceding, except that a large
quantity of AsO^{3} and but little SbO^{3}
are given off.
(4) in forceps. --
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. As stephanite, except that much arsenic is
given off and but little antimony.
(8) Special reactions. --
* * * * *
Mineral. Horn silver
Formula. AgCl.
Behavior
(1) in glass-bulb. Fuses, but undergoes no further change.
(2) in open tube. --
(3) on charcoal. Fuses readily in the oxidizing flame. In the
reducing flame is slowly reduced yielding
metallic silver.
(4) in forceps. --
(5) in borax. --
(6) in mic. salt. --
(7) with carb. soda. Is rapidly reduced to metallic silver.
(8) Special reactions. If cut up into small pieces mixed with oxide
of copper and then heated before the
oxidizing flame upon charcoal, it colors the
flame blue.
THE END.
* * * * *
Transcriber's Notes:
Text italicized in the original book is surrounded by '_'.
This book had many columnar tables, often split across pages. These
have been transformed in data sheets for readability.
The notation ^{#} is used for superscripted numbers, indicating
the composition of the various chemical compounds.
Some of the element symbols were differenced by markings that
were not defined in the book, but are supposed to be valence
markings. These have been transcribed as follows:
'.' or ',' above element symbol [?.Symbol] or [?,Symbol]
'-' above element symbol [=Symbol]
'-' through element symbol [Symbol=]
...
So [...Al] where the original text had Al
_
[=M] where the original text had M
,,,
[,,,Sb] where the original text had Sb
...
[...Fe=] where the original text had Fe, line through the Fe.
*** End of this LibraryBlog Digital Book "A System of Instruction in the Practical Use of the Blowpipe - Being A Graduated Course Of Analysis For The Use Of Students And All Those Engaged In The Examination Of Metallic Combinations" ***
Copyright 2023 LibraryBlog. All rights reserved.