A System of Instruction in the Practical Use of the Blowpipe by Anonymous

A >> Anonymous >> A System of Instruction in the Practical Use of the Blowpipe

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18

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. BAILLIERE, 290 BROADWAY,
AND 219 REGENT STREET, LONDON.

PARIS: J.B. BAILLIERE ET FILS, RUE HAUTEFEUILLE.
MADRID: C. BAILLY-BAILLIERE, CALLE DEL PRINCIPE.
1858.

* * * * *

ENTERED according to Act of Congress, in the year 1858, by
C.E. BAILLIERE,
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_.

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18