A COMPENDIOUS MANUAL
0OF
QUALITATIVE CIHEMICAL ANALYSIS.
BY
CHARMELS W. ELiOT,             Pti AN-K IT STOPlER.,
PROFESSOR OF ANALYTICAL CHEMIISTRY PROFESSOR OF GENERAL AND INDUSAND MIETALLUREGY,             TRIAL CHEMISTRY,
IN THE MXASSACHUSETTS INSTITUTE OF TECHINOLOGY.
NEW  YORK:
D. VAN  NOSTRAND, PUBLISHIER,
23 MURRAY STREET AND 27 WARREN STREET.
1869.




EnOtied according to Act of Congress, in tile yfar 1S68, by
FRANK HI. STORIER AND CHARLES) W. ELIOT,
in thl  Clcrk's Office of the District Court of the District of 1Massachustt.s.




PRE FAOCE.
TuE authors have endeavored to include in this shortl
treatise enough of the theory and practice of cqalitatli've
analysis, " in the wet way," to bring out all the reasoning'
involved in the subject, and to give the student a fir1
hold upon the general principles and nmetlods of the art.
It has been their aim to give only so much of mnechanical detail as is essential to an exact comlprehension of
thle methods, and to success in the actual experimaents.
Hence, the multiplication of different tests or processes,
having essenitially the same object, has been purposely
avoided.  For the same re"son, none of the rare elenments are aliuded to.  Th1e m anual is intended to Pmeet
the wants of the general stundent, to whom  thze study
is chiefly valuable as a neans of mental discipline, and
as a comppact exaLmple of the scientific method of arriving
at truth.  To professional students who wish to make
themselves expert analysts, this little book offers a logiceal
introduction to t1e subject —an outl;ine whLenich is truLStworthy as far as it goes, but'' which mneeds to be filled
ia and enllarged by t he subsequent use of some more
elaborate treatise as a book of reference.  Prof. Johnson,




4                       PREFACE.
of Yale, has supplied this need with his excellent edition
of Fresenius's comprehensive manual.
The authors believe that they have put into the following pages as much of inorganic qualitative analysis as is
useful for training, and also as much as the engineer,
physician, agriculturist, or liberally educated man needs
to know.  The book has been written for the use of
classes in the Institute of Technology, who have already
studied the authors' " ianual of Inorganic Chemistry."
It is simply an implement devised to facilitate the giving
of thorough instruction to large classes in the laboratory.
It is the authors' practice to examine their classes orally
every fout or five exercises, in order to secure close attention to the reasoning of the subject.  WVith this exception, the art is studied exclusively in the laboratory, tools
ill hand.  Fifty laboratory exercises of two hours each
have proved sufficient to give their classes a mastery of
the subject as it is presented in this manual.
It is scarcely necessary to say that this little, work is a
compilation from  well-known authorities, among'vt which
may be particularly mentioned  the works of Galloway,
W5ill, Fresenius, and Northcote & Church.
BOSTON, A P'il, 1869.




TABLE OF CONTENTS.
Page,
n,-roduction.  Qualitative analysis defined.' Scope of this nzanual.
Identifying compounds.  Division of the subject..............          9-12
PARIT  I.
Chaptor I.  Example of the separation of two elements.  Division of
twenty-four metallic elements into seven classes..............   13-26
Chiapter II. Class I, Chlorides insoluble in water and acids. Lead.
Silver.  M.ercury.........................................    26-29
Chapter III.  Class IT.  Sulphides insoluble in water, dilute acids,
and alkalies.  M[ercury.  Lead.  Bismuth.  Copper.  Cadmimon.
The precipitation of Classes II and III.......................   29-37
Chalper IV.  Class III.  Sulphides insoluble in water or dilute acids,
but soluble in alkaline solutions.  Arsenic.  Antimony. Tin.
LGold and Platinum.].......................................   3 8-4
Chapter V. Class IV.  Hydrates  insoluble  in water, ammonia-vwater, and solutions of ammoniumn-salts.  Simultaneous precipitation of some salts which require an acid solvent.  Treatmein t
of the precipitate, produced by ammonia water, with oxalic acid.
Iron. Manganese.  Chromium. Aluminum. Separation of Class
IV from Classes II and III. iThe original condition of iron.  The
use of chloride of ammIonium.  Interference of organic matter..   45-54
Chapter VI. Class V.  Sulphides insoluble in water, and in saline or
alkaline solutions.  langanese.  Zinc. Nickel. Cobalt.  Separation of Class V fromir  Class IV.............................   54-60




6                         TABLE OF  CONTENTS.
Page.
Chapter VII.  Class VI. Carbonates insoluble in water, ammoniawater, and  saline solutions.  Barium.  Strontiu   m.  Calcium.
Separation of Class VI from the preceding classes....6........   61-GG
Chapter VIII. Class VII. Three common metallic elements not
comprised in the preceding classes.  Ml{agnesium. Sodium. Potassium.  Table for the separation of the seven classes of the metallic elements.............................   67-72
Chapter IX. General tests for the non-metallic elements.  The
classes of salts treated of.  General reactions for acids.  lMetallic
elements to be first detected. The bariuml test.  The calcium
test.  The silver test.  Nitrates, chlorates, and acetates.......   72-82
Chapter X. Special tests for the non-metallic elements.  [Effervescence. Carbonates.  Cyanides.  Sllphides. Sulphiites.  Hyposulphites.  Chromates. Arsenites and Arseniates.  Sulphates.
Phosphates.  Oxalates.  Tartrates.  Beorates.  Silicates.  Fluorides.  Chlorides.  Bromides.  Iodides.  Nitrates.  Chlorates.
Acetates....,...........................................          83-97
PABT II.
Preliminary Treatment.  Order of Procedure.  1. Treatment of a
salt, mineral, or other non-metallic body.  2. Treatment of a
metal.  3. Treatment of a liquid.  Husbanding material.......   99-100
Chapter XI. Treatment of a salt, mineral, or other non-metallic
solid... P. Preliminary examination in the dry way.
Closed-tube test. Destruction of organic nmatter.  G ases or
vapors to be recognized.  Sublimates. Reduction test. 1M1etallic
globules....  Dissolving a salt, mineral, or other nonmetallic solid, free from  organic matter.  Dissolving in water.
An aqueous solution.  Dissolving in acids. An acid solution.
Treatment of insoluble substances.  List of such
substances.   Prelimina ry  dry-way  tests.   Fusions.  Treatment of the fused imass. Fusion for alkali-metals. DeflagratiOnl,............................ 100-126
Chapter XIi. Treatment of a pure metal or alloy. Action of nitric
acid on metals.  Gold test.  Platinumi test................... 126-130
Chapter XIII. Preliminary examination of a liquid.  Evaporation
test.  Testing with litmus.  Testing for amnonia............. 130-132




TABLE OF CONTENTS.                              7
PART IIL
Page.
Chapter XIV. Reagents.  Acids. Sulphuretted hydrogen. Ammoniawater. Arnmonium-salts.  Caustic soda. Sodiuml salts. Potassinm  salts. Nitrate of silver. Calcium  salts.  Barium  salts.
Acetate of lead. Lead paper. Sulphate of magnesiun.  Ferric
chloride. Nitrate of cobalt. Sulphate of copper. Protochloride
of tin. Oxide of mercury.  Chloride of mercury. Bichloride
of platinum.  Solution of indigo.  Litmus paper.  Turmeric
paper.  Starch paste. Water............................... 133-145
Chapter XV. Utensils. List of utensils. Reagent Bottles. Testtubes. Test-tube rack. Flasks. Beakers. Funnels. Filtering.
Filter-stand. Porcelain dishes and crucibles. Lamps.  Blastlamps and blowers. Iron-stand. Tripod. Wire-gauze. Triangle.:,Water-bath.  Sand-bath.  Platinum-foil and wvire.  Pincers.
Platinum crucibles. Wash-bottle. Glass tubing. Stirring-rods.
Cutting and cracking glass. Bending and closing glass tubes.
Blowing  bulbs. Caoutchouc.  Corks. Gas-bottle. Self-regulating gas-generator. Mortars. Spatule.                145-186








QUALITATIVE ANALYSIS.
INTRODUCTION.
1. QUALITATVE ANALYSIS, in the widest sense of the
term, is the art of finding out the elements contained in
compound substances. This general definition has important limitations in practice. In the first place, the art,
as commonly taught, applies almost exclusively to mineral, or inorganic, substances, and touches only incidentally
upon the multifarious compounds of carbon with hydrogen, oxygen, nitrogen, and a few other elements, which
form the subject-matter of that branch of chemical science
called organic chemistry. Again, the analysis of gases
constitutes a distinct branch of analysis, requiring methods
and apparatus of its own, and therefore to be most advantageously studied by itself. These deductions made,
there remains the analysis of inorganic solids and liquids,
which is in fact the main subject of qualitative analysis in
the present technical sense of the term.
Of the sixty-five recognized chemical elements, only the
thirty-four most important are embraced in the systematic
course of this manual. ieans of detecting a few other
less common elements are incidentally given; but the elements which are so rare as to be at present of little in



10                IDFENTIFYING COM]POUNDS.            ~ ~ 2, 3
terest except to the professional chemist or mineralogist,
are not alluded to.
2. Some previous knowlecdge of general chemistry is
essential to the successful study of qualitative analysis.
it is assumed  that tile student knows something of the
com mmon elemen-ls and of their nmost important combinations, that he is familiar with the principal laws which
govern chemical chang-es, and that he possesses a certain
skill in the simplest manipulations. The tools and operations employed in qualitative analysis are few and simlple;
but neaitness, meethod in workinT', and a vigilant attention
even to the minutest details, are absolutely essential. As the
various substances used or produced in the operations of
analysis will not be particularly described, the careful
student will keep at hand some text-book on general
chemistry, to which he can constantly refer to refresh his
recollection of the fornmulT and physical and chem~ ica1l
properties of the substances referred to.  It should be
observed that it is often very difficult-in fact, impossible
in the present state of hnowledge-lto express in e-xact
eqTuations the involved or obscure reactions which occur
in comnplec  mixtures d-uring  tlhe operations of analysis.
It is a useful  exercise for students to write ont in' equations the simpler chemical chlanges which occur in analysis; but when the attempt is made to put a com plex
reaction into numerical symbols, the equations are apt
to expcress either more than we know, or less.
3. Al1-houaggh the detection of the elements con'qaineod in
compound substances is the u1timate object of analysis, it
is only by exception that the elements thenmselves are
isolated, and recognized in their uncombined condition.
A.n element is genemrally recolgnized through some familiar




~ 3:IDENTIFYING COMPOUTDI)o           11
cor:npound, whose apparition proves the presence of all
tile elements it contains, just as the presence of any word
rupon this page makes it sur e that the letters with which
it is spelt are imprinted there. If, as the result of a cefinite series of operations upon somle unknovwn body, the
hydrated oxide of iron be produced, no iron having been
added during any stage of the process, the proof of the
presence of iron in the original body is quite as certain as
if the gray metal itself had been extracted from it. If
some well-klnown sulphate, like sulphate of lead, or of
batrium) for example, result from a series of experimentts
upon some unknown mineral, it is certain that the mineral
contained sulphur; provided only that no sulphur has
been introduced in any of the chemical agents to whose
action the mLineral has been subimitted.
The compounds through which the elements are recognized are necessarily bodies of known appearance, deportment, a-nd properties. They are, in fact, bodies of various,
though always definite, composition; oxides, sulphides,
chlorides, sulphates, and many other salts, are thus madc
the means of identifying one or more of the elements
which they contain. The object of the analyst is to bring
out, from the unknown substance, by expediious processes
and unnder conditions which adnit of no doubt as to their
testinmony, these identifying compounds, with whose appearance and qualities he has previously maLde himself acquainted. As he follows the course of experiments laid
down in this manual, the student will gradually acquire,
with the aid of frequent references to a text-book of
general chemistry, that stock of information concerniing
the identifying compounds which must be always ready
for use in his mind, and at the sam-e time he will be
mnade familiar with the character of the methodical iprocesses whlich secure a prompt and sure testimuony to




12               IDENTIFYING COMPOUNDS.                ~ 4
the elementary composition of the substances hle examines.
4. The subject is treated in two parts or divisions, of
wVhich the first contains a systemlatic course of examina~tion for slrbstances in solution, lwhen once that solution
has been made; and the second treats chiefly of the preliminary exalnination of solids and the means of bringing
them into solution.




PART FIRST.
CHAPTER I.
DIVISION OF THE METALLIC EL.EMENTS INTO CLASSES.
5. Examiple of the Separation of two Elemnents. Put a small
crystal of nitrate of silver and a small crystal of sulphate
of copper into a test-tube (~ 155), and dissolve them in
two teaspoonfuls of water, warming the water at the lamp
to facilitate the solution. Add to this solution a few drops
of dilute chlorhydric acid (~ 98). Shake the contents of
the tube violently, wait until the curdy precipitate, which
the acid produces, has separated from the liquid, and then
add one more drop of chlorhydric acid. If this drop produces an additional precipitate, repeat the operation until
the new drop of acid produces no change in the partially
clarified liquid. Then, and not till then, has all the silver
which the original solution contained been precipitated in
the form of chloride of silver, an unemployed balance or
excess of the reagent, chlorhydric acid, remaining in the
clear liquid; this liquid can be readily separated by filtration from the curdy chloride. Shake the contents of
the test-tube, and transfer them as completely as possible
to a filter (~ 160), supported in a very small glass funnel
(~ 159), which has been placed in the mouth of a test-tube.
With the wash-bottle (~ 170) rinse into the filter that
2




14                 THE TEPRM CLASS.                 ~ 6
portion of the precipitate which has adhered to the sides
of the first test-tube.  When the filtrate has drained completely from the precipitate, set the test-tube which has
received it aside. W~ash the precipitate together into the
apex of the filter by means of a wash-bottle with a fine
outlet; and, in order to wash out the soluble sulphate of
copper which adheres to the precipitate, fill the filter full
of water two or three times, throwing away this washwater when it has passed through the filter.
The complete separation of the silver and copper which
were mixed in the original solution is already accomplished; the silver is on the filter in the form of chloride;
the copper is in the clear, bluish filtrate.  This speedy
and effectual separation of the two elements is based upon the fact that chloride of silver is insoluble, while chloride of copper is soluble, in water and acid liquids.
Such differences of solubility are the chief reliance of the
analyst.
6. Definition of the termn " Class." Class I. In this experiment only two elements have been separated. It
might obviously be very difficult, if not impossible, to find
a special reagent for every element, which would always
precipitate that single element and never any other.
Chlorhydric acid, for example, which precipitates silverm so
admirably from any solution containing that element, is
capable of eliminating two other elements under like conditions. The lower chloride of mercury (calomel) is insoluble in water and weak acids.  Chloride of lead is
sparingly soluble in cold water, and is still less soluble in
water acidulated with ehlorhydric acid.  The chlorides of
the other metallic elements are all soluble in water and
acids under the conditions of the analytical process.
There are embraced in the scope of this manual twenty



~ 6                 THE TERM CLASS.                   15
two common elements of the sort ordinarily called metallic, most of which form those oxides relatively poor in
oxygen which are collectively designated as bases. If
chlorhydric acid were added in proper quantity to a solution imagined to contain all these elements, three, and
only three, of the twenty-two elements would be precipitated as chlorides.  After filtration and washing, a mixture of chloride of silver, chloride of lead, and subehloride
of mercury, would remain upon the filter, and all the other
elements would have passed into the filtrate. Silver, lead,
and mercury, the three elements thus separated from the
rest by this well-marked reaction with chlorhydric acid,
constitute a class, the first of several classes into which the
metallic elements are divided for the ends of qualitative
analysis. Each class is characterized by some clear reaction which suffices, when intelligently applied, to separate the members of any one class from  the other classes.
The chemical agent, by means of which this distinctive reaction is exhibited, is called the general reagent of the class.
Thus, chlorhydric acid is the general reagent of the first
class.
This division of the elements into classes renders it unnecessary to find means of separating each individual element from all the others.  In the systematic course of an
analysis, the classes are first sought for and separated;
afterwards each class is treated by itself for the detection
of its individual members.  It is an incidental advantage
of this division of the elements into classes, that, when the
absence of any whole class has been proved by the failure
of its peculiar general reagent to produce a precipitate, it
is unnecessary to search farther for* any member of that
class. Mluch time is thus saved; for it is as easy to prove
the absence of a class as of a single element. The full
treatment of the first class of elements, comprising, as we




16                      CLASSES.                  ~~ 7, 8
have seen, silver, lead, and mercury, is the subject of Chapter II.
7. Erper'eimrent to illustrate the Division of the Metallic
Elements into Classes.  WTe proceed to demonstrate experimentally the chemical facts upon which rests the
division of the other metallic elements into convenient
classes.
Prepare a complex solution, by mixing together in a
small beaker (~ 158) the following solutions, viz.:-a solution of chloride of copper (CuC12) prepared by dissolving a few grains of oxide of copper in chlorhydric acid;
a solution of arsenious acid in chlorhydric acid; a solution of ferrous chloride prepared by dissolving a little fine
iron wire or filings in chlorhydric acid; an aqueous solution of chloride of zinc; an aqueous solution of chloride
of calcium; an aqueous solution of chloride of magnesium; an aqueous solution of chloride of sodium. If the
solutions be all moderately strong', a small teaspoonful of
each solution will be enough.  Dilute the mixture thus
prepared with its own bulk of water. Should any turbidity or precipitate appear, add chlorhydric acid, little by
little, until the solution becomes clear. This solution is
representative; it contains at least one member of each
of the classes of elements which remain to be defined. It
contains no member of the first class, which may be consistently supposed to have been previously precipitated,
as in the foregoing experiment (~ 5), an excess of chlorhydric acid remaining in the liquid.
8. Definition of Classes II and III. Pass a slow current
of sulphydric acid gas (~ 107) from a gas-bottle or generator through the acid liquid in the beaker.  This operation must be performed under a hood.  A dense, dark



~ 8                      CLASSES II AND  III.                              17
colored  precipitate will immediately  appear, and  gradually increase in bulk.  When the gas has flowed continually for five or ten  minutes through  the  liquid, stop  the
stream, stir the liquid well, and blow out the sulphydric
acid which lies in the beaker.  If after the lapse of two or
three  minutes the  liquid  smells distinctly  of sulphydric
acid, it is saturated with  the gas, and  it is sure  that the
reagent has done its work.   If the liquid does not retain
the  characteristic  odor, the  gas must be  again  passed
through it, until saturation is certainly attained.
Pour the contents of the beaker, well stirred up, upon
a  filter, supported  over  a  test-tube  or  second  beaker.
Rinse the  first beaker once with  a teaspoonful of water,
and transfer this rinsing water to  the  filter, allowing  the
filtered liquid  to  mix  with  the  original filtrate.   Label*
this  filtrate  "Filtrate  from   II  and  III"  (classes), and
preserve it for later study.
If any considerable quantity of precipitate has adhered
to the sides of the original beaker, it may be detached and
washed into the filter by means of a sharp jet of water
from  the wash-bottle.  The precipitate, as it lies upon the
filter, must then be washed once or twice with water; the
wash-water is thrown away.  The washed precipitate
consists of a mixture of sulphide of copper (CuS) and ter* The student should at once make it a rule to label every filtrate or precipitate
which he has occasion to set aside, even for a few moments. A bit of paper large
enough to carry a descriptive symbol or abbreviation should be attached to the
vessel which contains the liquid or precipitate. Paper gmmrned on the back is convenient for this use.
This habit, once acquired,will enable the student to carry on simultaneously, without
error or confusion, several operations. He may be throwing down one precipitate,
washing another, filtering a third, and dissolving a fourth, at the same time, and the
four processes may belong to as many different stages of the analysis. There will be
no danger of error, if labels are faithfully used; and a great deal of time will be saved.
The unaided memory is incapable of doing such work with that fell certainty, admitting of no suspicion or after-qualms of doubt, which is alone satisfying, or indeed, admissible, in scientific research,




18                CLASSES II AND III.               ~ 8
sulphide of arsenic (As SA). The fact that these sulphides are precipitated under the conditions of this experiment proves that they are both insoluble in weak acid
liquors. They are also both insoluble in water. But an
important difference between the two sulphides nevertheless exists, a difference which affords a trustworthy means
of separating one from the other.
When the water has drained away from the precipitate,
open the filter upon a plate of glass, and gently scrape
the precipitate off the paper with a spatula of wood or
horn. Place the precipitate in a small porcelain dish (~
162), pour over it enough sulphydrate of sodium solution
(~ 117) to somewhat more than cover it, and heat the
mixture cautiously to boiling, stirring it all the time with
a glass rod. The quantity of sulphydrate of sodium solution to be employed varies, of course, with the bulk of
the precipitate; but in this case two or three teaspoonfuls
will probably suffice. It is very undesirable to use an unnecessarily large quantity of the reagent.  A portion of
the original precipitate remains undissolved; but a portion has passed into solution. Filter the hot liquid again
The black residue on the filter is sulphide of copper,
which is insoluble, not only in water and weak acids, but
also in alkaline liquids.  To the filtrate, collected in a testtube, add gradually chlorhydric acid, until the liquid has
an acid reaction on litmus paper (~ 148). A yellow precipitate of sulphide of arsenic will appear as soon as the
alkaline solvent which kept it in solution is destroyed.
The sulphide of arsenic differs from the sLlphide of copper in that it is soluble in alkaline hydrates and sulphides.
But in this series of experiments copper and arsenic
stand as representatives of classes. The following comm-on elements have sulphides which  are insoluble  in




~ 8                CLASSES II AND III.                19
water, weak acids, and alkaline liquids:-Lead, mercury,
bismuth, cadmium  and copper.  These elements constitute Class II in our system of analysis. The following
elements have sulphides which are insoluble in water and
weak acids, but soluble in alkaline liquids:-Arsenic,
antimony, tin (and the precious metals, gold and platinuml).  These elements constitute Class III.  If all the
elements of both groups had been present, the analytical
process for separating one class from the other would not
have been different from that just executed.
The question may naturally suggest itself, how it happens that lead and mercury are included in Class II when
they were both precipitated in Class I. The chloride of
lead which is thrown down by chlorhydric acid, is not
wholly insoluble in water; hence it happens that the
lead is not completely precipitated in Class I.  That portion of the lead which has escaped precipitation as chloride in Class I, will be thrown down as sulphicle in Class
II, for the sulphide of lead is insoluble in water, weak
acids, and alkalies.  In regard to mercury, it will be remembered that there are two sorts of mercury salts, mercurous salts and mercuric salts.  The mercurous chloride
(calomel) is insoluble in water; but the mercuric chloride (corrosive sublimate) is soluble in water.  If, therefore, mercury be present in the form  of some mercurous
salt, it will be separated as chloride in Class I. If, on the
contrary, it be present in the form of some mercuric salt,
it will be separated in Class II as mercuric sulphide
(HgS), for this sulphide is insoluble in water, weak acids,
and alkaline liquids.  If a mixture of mercurous and
mercuric salts be contained in the original solution, mercury will appear both in Class I and Class II.
The treatment of Class II is fully discussed in Chapter
III.  The separation of Class III and the means of sepa



20                    CLASS IV.                    ~ 9
rating the members of the class, each from the others,
form the subject of Chapter IV.
9. Definition of Class IF. We now return to the study
of the filtrate from Classes II and III. Pour the liquid
into a small evaporating dish, and boil it gently for five
or six minutes, to expel the sulphuretted hydrogen with
which the fluid is still charged. To make sure that all
the gas is expelled, hold a bit of white paper moistened
with a solution of acetate of lead (~ 138) over the boiling
liquid; when the paper remains white, all the sulphuretted hydrogen is gone. Next add to the liquid in the
dish ten or twelve drops of strong nitric acid (~ 99), and
again gently boil the liquid for three or four minutes, in
order that all the iron present may be converted into ferric salts. Then pour the liquid into a test-tube, add to
it about one-third its bulkt of chloride of ammnonium
(~ 112), and finally add ammonia-water (~ 109), little by
little, until the mixture, after being well shaken, smells
decidedly of ammonia. A brownish red precipitate of
hydrated sesquioxide of iron will separate from the liquid.
Ammonia-water precipitates this familiar iron compound,
even in the presence of salts of ammnonium, such as the chloride of ammonium which has been expressly added, and
the nitrate of amnmonium which has been formed during
the neutralization of the acid liquid. Pour the contents
of the test-tube upon a filter, rinse the tube and the precipitate once with a little water, and preserve the whole
filtrate for subsequent operations.
Alumlninum and chromium are precipitated, as iron has
here been, by ammonia-water under the same conditions
and in the same form, namely, as hydrates. These three
elements, therefore, constitute the fourth class, whose
treatment forms the subject of Chapter V. The student




~10                    CLASS v.                    21
may be curious to know why the presence of ammoniumsalts is insisted upon before the elements of this class are
thrown down by ammonia-water.  The ammnonium-salts
have nothing to do with the precipitation of iron, aluminum and chromium; but by their faculty of forming soluble double salts, they prevent the partial precipitation of
certain other elements which are more conveniently dealt
with in classes which are to follow. The amlmonium-salts
keep in solution certain other elements which otherwise
would encumber Class IV.
10. Definition of Class E. We now proceed to the examination of the filtrate from the precipitate of Class IV.
Bring this liquid to boiling in a test-tube (or in a small
flask, if there be much liquid), and add sulphydrate of
ammonium (~ 110), little by little, to the boiling liquid,
as long as a precipitate continues to be formed. To make
sure that the precipitation is complete, shake the hot contents of the test-tube strongly, and then allow the mixture to settle until the upper portion of the liquid becomes
clear. Into this clear portion let fall a drop of sulphydrate of ammonium; when this drop produces no additional precipitate, the precipitation is complete. Filter off
the whitish precipitate of sulphide of zinc, and preserve
the filtrate for further treatment.
The element zinc, representing a new class of elements,
is precipitated under the conditions of the above experiment, because its sulphide, though soluble in dilute acids,
is insoluble in alkaline liquids. The metals manganese,
nickel, and cobalt resemble zinc in this respect, and these
four elements, therefore, form a new class, Class Y, in this
analytical method. The representative sulphide of this
class was not precipitated by the sulphydric acid when
that reagent was employed to throw down the members
2*




22                CLASSES VI AND VII.        ~~ 11, 12
of Classes II and III, because the solution was at that
time acid. Again, it was not precipitated with Class IV
by the ammonia-water, because the sulphydric acid gas,
with which the solution had previously been charged, was
expelled by boiling before the ammonia-water was added.
The complete treatment of Class V forms the subject of
Chapter VI.
11. Definition of Class VI. Add to the filtrate, from
Class V, two or three teaspoonfuls of carbonate of armonium (~ 111), and boil the solution. A white precipitate
of carbonate of calcium will be produced. After boiling,
allow the precipitate to settle until the upper portion of
the liquid is comparatively clear. To this clarified portion add a fresh drop of carbonate of ammonium. If
this drop produce an additional precipitate, more carbonate of ammonium must be added, and the boiling repeated.
To the partially clarified liquid add again a drop of carbonate of ammonium. This process of making sure of
the complete precipitation of the calcium is essentially
the same as that prescribed in precipitating the last class,
and is, indeed, of general application. When the precipitation of the calcium has been proved to be complete,
filter the whole liquid, and receive the filtrate in a small
evaporating dish. Calcium is separated in the form of carbonate under these circumstances, because this carbonate
is almost insoluble in weak alkaline liquids, when an
excess of carbonate of ammonium is present. The allied
elements barium  and strontium  behave in the same
way, so that these three elements, viz., barium, strontium,
and calcium, compose a new class-Class VI, whose complete treatment is set forth in Chapter VII.
12. Definition of Class VI1L  Of the twenty-two metallic
elements, which were to be classified (~ 6), only three




~ 12                 CLASS VII.                   23
remain, viz., magnesium, sodium, and potassium. It is
obvious that these three elements could not have remained
in solution through  all the operations to which the
original liquid has been submitted, unless their chlorides
and sulphides had been soluble in weak acids, and their
oxides, sulphides, and carbonates, soluble in dilute ammonia-water, at least in presence of dilute solutions of
amlmonium-salts. It is a fact that all these compounds of
sodium and potassium  are soluble in water, and in weak
acid, alkaline, and saline solutions; the magnesium
would have been partially precipitated in Classes IV, V,
and VI, but for the presence of ammonium-salts in the
solution. These three elements constitute Class VII.
Evaporate the filtrate from Class VI until it is reduced
to one-half or one-third of its original bulk. Pour a small
part of the evaporated filtrate into a test-tube; add a little
ammonia-water and a teaspoonful of phosphate of sodium
(~ 121), and shake the contents of the tube violently.
Sooner or later a crystalline precipitate will appear. This
peculiar white precipitate of phosphate of magnesium and
ammonium identifies magnesium; but as we have added
a reagent containing sodium, the filtrate is useless for
further examination. The liquid remaining in the evaporating-dish is then evaporated to dryness, and moderately
ignited until fuming ceases. All the ammoniacal salts
which the solution contained will be driven off by this
means, and there will remain a fixed residue, in which are
concentrated all the salts of magnesium  and sodium
which the original solution contained. In this case we
have proved the presence of magnesium; it remains to
indicate briefly the nature of the means used to detect
sodium.
Dissolve the residue in the dish, or a portion of it, in
three or four drops of water. Dip a clean platinum wire




24                    CLASS VII              ~~ 13, 14
(~ 168) into this solution, and introduce this wire into
the colorless flame of a gas or spirit-lamp (~ 163). An
intense yellow coloration of the flame demonstrates the
presence of sodium. A violent coloration would have
proved the presence of potassium.  Magnesium  compounds, when present, have no prejudicial effect on these
characteristic colorations. The means of detecting each
member of this last class in presence of the others will be
found described in Chapter VIII.
13. A condensed statement of the classification illustrated by the foregoing experiments is contained in the
table on the next page. All the common metallic elements are embraced in it. The place of the precious
metals gold and platinum is also indicated. The classification itself would not be essentially different, if all the
rare elements were comprehended in it. The general
subdivisions would be the same, although some of them
would embrace many more particulars.
14. It is essential to success to follow precisely the
prescribed order in applying the various general reagents.
Class I would go down with Class II, were chlorhydric
acid forgotten as the first general reagent. Class II
would be precipitated in part with Class IV and in part
with Class V, if sulphuretted hydrogen should not be used
in its proper place. A large number of the members of
the first five classes would be precipitated as carbonates
with Class VI, were they not previously eliminated by the
systematic application of chlorhydric acid, sulphuretted
hydrogen, ammonia-water, and sulphide of ammonium, in
the precise order and under the exact conditions above
described. It should be noticed that all the general reagents are volatile substances, which can be completely




THE SEVEN CLASSES OF THE METALLIC ELEMENTS.
CLASS I.        CLASS IL            CLASS m:V. CLASS IV.                  CLASS V.   CLASS VI.   CLASS VII.
Precipita-  Precipitated as sul-  Precipitated as sul-   Precipitated  by    Precipita-  Precipita-  Remaining
ted as    phides insoluble in  phides insoluble in   ammonia water,  ted as snl-  ted as car-  elements.
chlorides,  dilute  acids, and  dilute  acids, but   usually  as hy-   phides in-  bonates,          Distinnot  redissolvable  redissolved by al-   drates,              soluble  in              guished by
Ag                                                                                     Ca
byalkaline liquids,  kaline liquids,                           alkaline                  special C
Pb                                                        Fe              uBa,
fuids,                  tests, 
Hg              Pb                   As                   Al                           Sr                      o
Hg                  Sb                   Cr               Zn                       Mg
Bi                  Sn                                    Mn                       Na
[   [together with cerCd                 [Au]                                   Ni                       K
tain salts which reCu                 [Pt]                                   Co
quire an acid solvent.]
ND3
Car




26                     CLASS I.              ~~ 15, 16
removed by an evaporation to dryness followed by a very
moderate ignition.
15. The series of experiments just completed is merely
intended to demonstrate the principles in accordance with
which these twenty-two common elements are classified
for the purposes of qualitative analysis. The general plan
is here sketched. The practical details, essential to success
in the conduct of an actual analysis, will be given hereafter.
CHAPTER II.
CLASS I. CHLORIDES INSOLUBLE IN WATER AND ACIDS.
16. Example of the Precipitation of the lMembers of Class
I. Place in a test-tube five or six drops of a tolerably
concentrated aqueous solution of nitrate of silver, an
equal quantity of a solution of mercurous nitrate, and
two teaspoonfuls of a solution of nitrate of lead.  In
case the solution becomes turbid through the action of
carbonic acid dissolved in the water, pour in one or two
drops of nitric acid to destroy the cloudiness.
Add dilute chlorhydric acid to the solution, drop by
drop, and shake the mixture thoroughly after each addition of the acid, until the fresh portions of the latter
cease to form any precipitate on coming in contact with
the comparatively clear liquor which floats above the insoluble chlorides. Finally add three or four more drops
of the acid to insure the presence of an excess of it in
the solution.




~17                     CLASS I.                    27
17. Analysis of the Mixed Chlorides.  The following
method of separating the chlorides of lead, silver, and
mercury, one from another, depends upon the facts: —st.
That chloride of lead, though but little soluble in cold
water, dissolves readily in boiling water, while chloride of
silver and subchloride of mercury are as good as insoluble
in that liquid. 2d. That chloride of silver is soluble in
ammonia-water; and 3d. That subchloride of mercury is
discolored by ammonia-water without dissolving.
To effect the separation:-Collect the precipitate, produced by chlorhydric acid, upon a filter, allow it to drain,
and rinse it with a few drops of cold water. Place a
clean test-tube beneath the funnel which contains the
filter and precipitate, thrust a glass rod through the apex
of the filter, and wash the precipitate off the filter into
the test-tube by means of a wash-bottle which throws a
fine stream.
Heat the mixture of water and precipitate to boiling,
pour the hot liquor, but not the precipitate, upon a new
filter, and add to the filtrate two or three teaspoonfuls of
dilute sulphuric acid (~ 103). A white cloud of sulphate of lead will be formed in the midst of the  Test
liquid. In case the precipitate contains a large  for
proportion of chloride of lead, it may happen that  Pb'
the hot water will take up so tmuch of it that crystals of
the chloride will separate from the clear aqueous solution
as it becomes cold, or that the liquor will be rendered
cloudy by the deposition of numerous small particles of
the chloride.
After the mixed precipitate of chloride of silver and
subehloride of mercury which was left in the test-tube
has been boiled several times with fresh water, in order
to insure the removal of all the chloride of lead, transfer
the whole precipitate to the filter of the last paragraph,




28                     CLASS I.                   ~ 17
and pour some ammonia-water which has been heated in
another test-tube, directly upon the white precipitate as it
lies on the filter, placing a clean test-tube beneath the
funnel. The chloride of silver, dissolved by the ammoniawater, will pass into the filtrate, while the subehloride of
mercury suffers decomposition, and is converted into an
obscure compound of mercury, chlorine, nitrogen, and
hydrogen, which remains upon the filter in the form of
an insoluble black or gray powder.
To confirm the presence of silver, neutralize the ammoniacal solution with dilute nitric acid (~ 100), and observe that the chloride of silver is reprecipitated.
To confirm the presence of mercury, the metal itself
may be set free by heating the dry residue with carbonate
of sodium (~ 118) in a glass tube. To insure the success
of this experiment, wash into the lowest point of the
filter the whole of the black residue, including those portions which have remained adhering to the sides of the
test-tube.  As soon as the last drops of liquid have
drained from the filter, dry the latter, either in a dish
upon a water-bath, or by spreading it open upon a ring of
the iron stand (~ 165) placed high above a small flame of
the gas-lamp. WThen the precipitate is completely dry,
Test scrape it from the paper, mix it with an equal
for  bulk of carbonate of sodium, previously dried over
lg'  the gas-lamp on platinum foil (~ 168), and transfer
the mixture to the bottom of a glass tube, No. 6 (~ 171),
closed at one end. Then wipe out the inside of the tube
with a tuft of cotton fixed to a wire, or with a twisted strip
of paper, and heat the closed end of the tube for two or
three minutes in the flame of a gas-lamp. A sublimate of
finely divided metallic mercury will form upon the walls
of the tube; the metal will cohere to visible globules
when scratched with a piece of iron wire.




~~ 18, 19     TABLE FOR CLASS I. —CLASS II.             29
18. An outline of the operations described in the foregoing paragraphs may be presented  in tabular form, as
follows:The General Reagent (HCl) of Class I precipitates PbCl2, AgC1
and HgCl.  The precipitate is boiled with water:PbC12 goes into  AgC1 and HgCl remain undissolved. On treatsolution. Con- ing the mixture with ammonia-water,
firm presence of
lead by precipitation of sul-   AgC1 dissolves.   A black compound of merphate of lead.   Confirm  presence  cury remains undissolved.
of silver with nitric  Confirm presence of mercuacid.             ry by isolating the metal.
CHAPTER III.
CLASS II. SULPHIDES INSOLUBLE IN WATER, DILUTE
ACIDS, AND ALKALIES.
19. Example of the Precipitation of the Members of Class
I. Place in a small beaker six or eight drops of a strong
solution of each of the following substances:-Chloride of
mercury (corrosive sublimate), chloride or nitrate of bismuth, of cadmium, and of copper, together with two or
three teaspoonfuls of a cold aqueous solution of chloride
of lead.  Fill the beaker half full of water, and add, drop
by drop, enough strong chlorhydric acid to redissolve the
basic chloride of bismuth which the water precipitates.
Place the beaker beneath a chimney or in a strong
draught of air, and saturate the solution with sulphuretted
hydrogen gas. To determine when enough sulphuretted
hydrogen has been passed through the liquid, remove the




30               ANALYSIS OF CLASS II.            ~ 20
beaker every four or five minutes from the source of the
gas, blow away the gas which lies in the beaker above the
liquid, and stir the latter thoroughly with a glass rod. If
after the lapse of two or three minutes, the liquid still
smells strongly of sulphuretted hydrogen, it is saturated
with the gas and. ready to be filtered. But in case no
persistent odor of sulphuretted hydrogen is observed, the
gas must be passed anew through the liquor until it has
become fully saturated. Since some of the substances
above enumerated are thrown down more quickly by sulphuretted hydrogen than the others, it is absolutely
necessary to employ the reagent in excess in order that
those members of the class which are least easily precipitated may not escape detection.
20. Analysis of the nMixed Sulphides. The following
method of separating the members of Class II depends
upon the facts:-Ist. That mercuric sulphide is insoluble
in dilute nitric acid, while the other sulphides are soluble
therein. 2d. That sulphate of lead is insoluble in acidulated water, while the sulphates of the other members of the
class are soluble. 3d. That hydrate of bismuth is insoluble in ammonia-water, while the hydrates of cadmium and
copper are soluble in that liquid. 4th. That sulphide of
cadmium is soluble, and sulphide of copper insoluble, in
hot dilute sulphuric acid.
To effect the separation:-Collect the precipitated sulphides upon a filter; wash the precipitate thoroughly with
water, in order to completely remove the chlorhydric acid
which adheres to it; make a hole in the filter, and rinse
the precipitate into a small porcelain dish. Carefully decant the water from the precipitate, pour upon the latter four or five times as much dilute nitric acid as would
be sufficient to cover it, and boil the mixture during five




~ 20            SEPARATION OF MERCURTY.              31
mninutes, stirring it constantly with a glass rod, and adding
dilute nitric acid at intervals to replace the liquid which
evaporates.  A heavy dark mass of sulphide of mercury,
mixed with some free sulphur resulting from the decomposition of the other sulphides, will remain undissolved.
Decant the nitric acid solution into a filter, collect the filtrate in a second porcelain dish, and evaporate it nearly
to dryness.
Pour water upon the residue insoluble in nitric acid
which was left in the first dish, to remove the adhering
liquid, and after this wash-water has been decanted, boil
the residue with as nluch aqua regia (~ 101) as will barely cover it. Dilute the acid solution with an equal volnine of w-ater, remove from it, by filtration or otherwise,
any particles of free sulphur which may remain undissolved, and add to it almost, but not quite, enough amnonia-water to neutralize its acidity. Place in the still
slightly acid solution a small bit of bright copper wire,
warm the liquor, and observe that metallic mercury is deposited upon the copper as a white silvery coating.  Test
After the lapse of ten or fifteen minutes, dry the  for
wire upon blotting paper, drop it into a narrow
glass tube which has been sealed at one end, and heat it
at the lamp. Metallic mercury will sublime, and be deposited as a dull mirror upon the cold portions of the
glass. By scratching the sublimate with the point of a
bit of iron wire, the metal may be made to collect into
visible globules.
When the greater part of the free nitric acid has been
driven off from the filtrate which contains the mixed nitrates of lead, bismuth, cadmium and copper, transfer the
residual liquor to a test-tube, mix it with two or three
times its volume of dilute sulphuric acid, and leave the
mixture at rest during fifteen or twenty minutes.  Sul



32         SEPARATION OF LEAD AND BISMIUTI.        ~ 20
phate of lead will be thrown down as a heavy white powder, plainly to be seen in the test-tube, though it would
have been scarcely'visible in the white dish.
To confirm the presence of lead, collect the precipitate
upon a filter, wash it with water, transfer it to a test-tube,
pour upon it two or three times its volume of a solution
of normal chromate of potassium (~ 124), and heat the
mixture to boiling. The white sulphate of lead will be
converted into yellow chromate of lead, without dissolving, and the characteristic color of the latter may be
made manifest by collecting it upon a filter, and washing'
it with water until the excess of chromate of potassium
has been completely removed.
Collect the filtrate from  the sulphate of lead in a small
beaker, and add to it ammonia-water by repeated small
portions, taking care to stir the liquid thoroughly after
each addition of the ammonia, until a strong persistent
odor of the latter is perceptible. The hydrates of copper,
cadmium, and bismuth, will all be thrown down at first,
but the hycrhates of copper and cadmium will redissolve in
the excess of ammonia-water, and hydrate of bism uth will
alone be left as an insoluble precipitate.
To prove that this precipitate contains bismubth -Collect it upon a filter, allow it to drain, and dissolve it in the
smallest possible quantity of strong ehlorhydric acid,
poured drop by drop upon the sides of the filter; careTest fully evaporate the acid solution to the bulk of
for  two or three drops and pour it into a large testA   tube nearly full of water. A dense milky clond of
insoluble basic chloride of bismuth will appear in the
water. Since sulphate of lead is not absolutely insoluble
in water which contains nitric acid, a slight precipitate of
hydrate of lead might be produced on the addition of the
ammonia-water even when no bismuth was present in the




~ 20           SEPARArTION OF CADMlIUM.            33
solution. To prove the presence of bismuth, the oxychloride must always be carefully tested for.
The blue color of the ammoniacal filtrate from the hydrate
of bismuth indicates the presence of copper, and when well
defined is of itself a sufficient proof of the presence of this
element. But in the absence of a marked blue coloration
at this stage, copper should be specially tested for in the
manner described below.
To separate the cadmium from the copper, proceed as
follows:-Transfer the ammoniacal filtrate to a glass flask,
heat it to boiling, and drop into the boiling liquid sulphydrate of ammonium as long as a precipitate continues to
be formed. In order to be sure that the precipitation is
complete, remove the flask from the lamp at intervals,
shake it strongly, and allow its contents to settle, so that
a comparatively clear liquid may appear at the top, and
into this clear liquid pour a drop of the sulphydrate.
As a general rule, the operations of boiling and agitating tend to increase the coherency of precipitates, and
to render them in some sense granular, so that they separate completely from the liquid in which they form, leaving it clear and susceptible of rapid filtration.
Collect the precipitate upon a filter, rinse it once
or twice with water, and allow it to drain; then open
the filter on a plate of glass, scrape the precipitate off
the paper and put it in a porcelain dish.  Prepare a
dilute sulphuric acid by mixing 1 part by measure of
the strong acid (~ 103), with 5 parts of water. Cover
the precipitate in the dish liberally with this dilute
acid, and heat the mixture until it actually boils; then
pour the boiling liquor upon a filter, and collect the
clear filtrate in a beaker. Sulphide of cadmium  alone
will dissolve in hot dilute acid of the prescribed strength,
the black sulphide of copper remaining intact.




34          TESTS FOR CADMIUM AND COPPER.         ~ 21
To prove the presence of cadmium, pass sulphuretted
Test hydrogen gas into the acid filtrate, and observe
for  that the liquor immediately becomes cloudy from
Id  the presence of minute particles of sulphide of
cadmium of characteristic yellow color. After some time
this precipitate will collect at the bottom of the liquid.
To prove the presence of copper, in case no blue coloration was visible in the filtrate from the hydrate of bismuth,
transfer the black precipitate, insoluble in dilute sulphuric acid, to an evaporating dish, dissolve it in a few drops
of boiling, concentrated nitric acid, remove and wash the
the spongy mass of sulphur which is set free, neutralize
the nitric acid with ammonia-water, acidify the solution
with acetic acid (~ 105), transfer it to a test-tube, and add
one or two drops of a solution of ferrocyanide of potasTest sium (~ 125). A peculiar reddish-brown precipifor  tate of ferrocyanide of copper will fall in case
Cu. much copper be present, and even when the proportion of copper in the solution is extremely small, a light
brownish-red cloudiness will be produced.
In the absence of copper, yellow sulphide of cadmium
would at once be thrown clown by the sulphydrate of ammonium, when this reagent is added to the filtrate from
the oxide of bismuth; and no further evidence of tlhe presence of cadmium would be required.
21. The operations above described may be presented
in tabular form, as follows:



~ 22                   TABLE FOR CLASS IL                          35
The General Reagent (H2S) of Class II precipitates HgS, PbS, Bi2S3,
ClS, and CuS (as well as members of Class III, which are subsequently
separated by solution in sulphydrate of sodium). The precipitate is boiled
with nitric acid:A residue of   The nitrates of Pb, Bi, Cd, and Cu go into solution. On
HgS, plus S, adding dilute sulphuric acid to the concentrated solution:remains.
Confirm presence of mer-   PbS04, is    The sulphates of Bi, Cd, and Cu remain
cury  with  thrown down. in solution. On adding an excess of amcopper wire.  Confirm  the  monia-water: —
presence of
Pb by converting     Hydrate of   Compounds of Cd and of Cu
PbSO4  into  Bismuth  is remain in solution. Throw
PbCrO4.      thrown down. down CdS and CuS with
Confirm Biby  (H-4) I-IS, and boil with diprecipitating  lute sulphuric acid:the oxychloride.
CdSO4 goes CuS remains
into solution. undissolved.
Confirm pres- Confirm presence of Cd by  ence of Cu by
precipitation  testing with
of CdS.       ferrocyanide
of potassium.
22. The method of Separating Class I froz  Class II has
already been particularly described in ~ 6.  It should be
observed, however, that even if no  member of Class I
were present in the mixture to be analyzed, it would still
be necessary to acidulate the liquid with chlorhydric acid,
before passing the  sulphuretted  hydrogen, in  order to
prevent the precipitation of members of Classes IV and V,
and to secure the complete precipitation of the members
of Class III.
The  liquid  should  be watched  attentively  when  the
stream   of sulphnretted  hydrogen  first begins  to  flow
through it, since useful inferences may often be drawn
from  the various phenomena which present themselves.
a.  Thus,  the formation  of a white precipitate which




36         SEPARATION OF CLASSES II AND III.      ~ 22
afterward changes to yellow, orange, brownish-red, and
finally to black, as the liquid gradually becomes saturated
with the gas, indicates the presence of mercuric chloride.
The white precipitate at first formed is a compound of
chloride and sulphide of mercury (HgCl,; 2HgS), but by
the action of successive portions of sulphuretted hydrogen, the composition and appearance of the precipitate is
changed, until it has been completely converted into
black sulphide of mercury.
b. If the precipitate is of a dull red color at first, afterward changing to black, the probable presence of lead is
indicated; for sulphuretted hydrogen throws down from
solutions which contain much free chlorhydric acid a red
compound of chloride of lead and sulphide of lead, which
is afterward decomposed, with formation of the black sulphide, when the solution becomes saturated with the gas.
c. A decided bright yellow precipitate would indicate
the presence of cadmium, arsenic, or tin; of these three,
cadmium is distinguished by the fact that its sulphide remains undissolved when the precipitate is treated with
sulphydrate of sodium to separiate the members of Class
III.
But even from solutions which contain no members of
Classes II or III, yellowish-white or milky-white precipitates of free sulphur are often thrown down; for sulphuretted hydrogen is easily decomposed, with deposition of sulphur, by a variety of oxidizing agents, such as
nitric, chromic, and chloric acids, and solutions of ferric
salts and of free chlorine. If the solution under examination contained much nitric acid, sulphuretted hydrogen
would have to be passed through it for a long time to destroy the acid, before the liquid could be saturated with
the gas. In this case the sulphur separates as a tenacious
mass of dirty yellow color; but in most instances, notably




~ 22           PRECIPITATION OF SULPIUR.             37
when the solution contains a ferric salt, the sulphur is
precipitated in the form of exceedingly mlinute particles,
which inpart to the solution a peculiar milkiness or opalescence. These particles are so fine that they pass through
the pores of filter paper; they cannot be completely removed by filtration.
If the original solution contains a chromate, its yellow
or reddish-yellow color will be changed to green by the
action of sulphuretted hydrogen; for the chromate is
reduced to the condition of sesquichloride of chromium:2MCr04+10HC1l+3H2  s  2CrC6+3S+2''Cl2+812-.
The sulphur is set free in the form of the minute white
particles above described, and remains suspended in the
green liquid, looking not unlike a green precipitate.
A white precipitate of sulphur would be thrown clown
even before the passage of sulphuretted hydrogen, in case
the original solution contained a hyposulphite; for this
class of salts is decomposed, with evolution of sulphurous
acid and deposition of sulphur, on the addition of the
general reagent (HC1) of Class I. Some sulphides also
are decomposed by chlorhydric acid, with deposition of
sulphur.  A gelatinous white precipitate of hydrated
silicic acid might also be formed at this stage in certain
circumstances, as will be explained hereafter (~~ 67, 80, a).
d. The immediate formation of a black precipitate indicates the presence of copper or bismuth, and it is to be
observed that either of these black precipitates would obscure the colors of the other sulphides of the class, and
conceal them if present.
e. If no precipitate appears even when the liquid has
become saturated with the gas, the absence of every
member of Classes II and III is, of course, to be inferred.
3




38                     CLASS I.L                  ~ 23
CHAPTER IV.
CLASS III. SULFIIDES INSOLUBLE IN WAVATER OR DILUTE
ACIDS, BUT SOLUBLE IN ALKALINE SOLUTIONS.
23. E xample of the Precipitation of the Mrembers of Class
[II. Place ill a small beaker six or eight drops of strong
solutions of the chlorides of arsenic, antimony, and tin.
Pour in enough dilute chlorhydric acid to half fill the
beaker, and, if need be, a sufficient number of drops of
strong chlorhydric acid to dissolve any cloud of basic
chloride of antimony which may appear in the liquor.
Pass sulph-uretted hydrogen gas through the solution,
in the manner described in ~ 19, until the odor of the gas
persists. Then collect the precipitated sulphides upon a
filter, and rinse the precipitate once or twice with water.
In the analysis of any complex solution of unknown
composition which might contain one or all of the members of Class III, the sulphides of this class would, of
course, all be thrown down at the same time as those of
Class II.  (Compare ~~ 8, 21.) It will be. well, therefore,
for the sake of illustration, for the student to dissolve the
present precipitate in sulphydrate of sodium, in order
that he may begin the treatment of Class III at the precise point at which this class would be encountered in an
actual analysis-namllely, with the sulphides of the class
in alkaline solution. To this end, allow the washed precipitate to drain, spread out the filter upon a plate of
glass, scrape the precipitate from the paper with a small
spatula of platinum, horn, or wood, and transfer it to a
porcelain dish. Pour upon the precipitate two or three
times as much of a solution of sulphydrate of sodium as




~ 24             ANALYSIS OF CLASS III.            39
would be sufficient to cover it, and boil the mixture very
cautiously, so as to avoid spattering. The precipitate
will soon dissolve, and no solid matter will be left suspended in the solution, except a few fibres of the filter
paper. It is such a solution as this which in an actual
analysis is examined for members of Class III.
Pour the alkaline solution into a beaker, and stir into
it, little by little, dilute chlorhydric acid until the liquid
exhibits an acid reaction. The sulphides of arsenic, antimony and tin, are re-precipitated, as such, together with
a quantity of sulphur derived from the decomposition of
the sulphydrate of sodium.
24. Analysis of the Mlixed Suiphides. The method here
given of separating arsenic, antimony and tin, depends:Ist. Upon the solubility of sulphide of arsenic in a dilute
aqueous solution of carbonate of ammonium, ancl the insolubility, or very slight solubility of the sulphides of antimony and tin in that liquid; 2d. Upon the oxidation of
the sulphides of antimony and tin by fusion with nitrate of
sodium; 3d. Upon the reduction of the compounds thus
formed to the metallic state by zinc; 4th. Upon the solubility of tin in chlorhydric acid.
To effect the separation:-Collect upon a filter the precipitate produced by acidifying the sulphydrate of sodium
solution, wash it with water to remove the acid and the
chloride of sodium which adhere to it, and allow it to
drain. Spread out the filter in a small porcelain dish,
and cover its contents with a dilute aqueous solution of
carbonate of ammonium-obtained by dissolving 1 part
of the solid carbonate in 12 parts of water, or by mixing
one volume of the strong solution (~ 111) employed as
the general reagent of Class VI, with two volumes of
water-and stir the mixture. After the lapse of four or




40              SEPARATION OF ARSENIC.            ~ 24
five minutes, pour the carbonate of ammonium solution
upon a new filter, collect the filtrate in a beaker, and stir
into it successive drops of dilute chlorhydric acid —taking care to add no more than a single drop of the acid at
any one time —until carbonic acid ceases to escape, and
the liquid exhibits a strong acid reaction when tested
with litmus paper. A bright-yellow precipitate of sulphide
of arsenic will separate immediately from the acid liquor,
in case much arsenic is present; or a yellow cloudiness
will appear at first, if the quantity of arsenic in the solution be minute. In the latter case the mixture must be
left at rest for some hours, in order that distinct yellow
flocks of the sulphide may collect at the bottom  of the
vessel.
To confirm the presence of arsenic:-Collect the precipitated sulphide upon a filter, dry it thoroughly at a gentle
heat, scrape it from the paper, place it in a narrow glass
tube which has been blown to a bulb at one end (see ~
175), and cover it with five or six times its bulk of a perfectly dry mixture of equal parts of carbonate of sodiumn
Test  and cyanide of potassium  (~ 127). The bulb of
for  the tube must be large enough to hold twice as
As. much of the mixture as is really to be placed in it,
in order that there may be room for the mass to swell
when it is heated and fused. After the bulb has been
charged, wipe out the inside of the tube with a tuft of cotton fixed to a wire, or with a twisted strip of paper, and
heat the contents of the bulb during two or three minutes
in the flame of a gas-lamp. A dark, lustrous ring of metallic arsenic will be deposited upon the cold walls of the
tube.
The mixed precipitate of sulphide of antimony and su. —
phide of tin, insoluble in carbonate of ammonium, is
treated as follows:-Scrape and wash all the precipitate




~ 24              ANTIMONY AND TIN.                41
off the paper into the dish, and add a teaspoonful of
strong nitric acid. Evaporate the mixture to the bulk of
a teaspoonful without heeding the mass of sulphur which
separates; then add to it two or three teaspoonfuls of a
strong solution of nitrate of sodium (~ 120), and evaporate the mixture to dryness with constant stirring. Heat
the dry mass until it fuses. When the dish has become
cold, fill it half full of cold water; when the water has
softened the cake of fused salts, stir the contents of the
dish, break up the lumps, and finally filter the insoluble
tin and antimony compounds from the soluble nitrates
which the water has taken up. This insoluble residue
must next be placed in a porcelain dish in contact with
a slip of clean, smooth, platinum  foil, and heated with
a little chlorhydric acid. Water is then added, and a
small fragment of zinc is put into the liquid. Tin and
antimony will be reduced to the metallic state by the
zinc. It is found that a part of the reduced anti-  Test
mony attaches itself firmly to the platinum  foil,  for
producing a very characteristic black stain upon   Sb.
the bright surface of the foil. Tin produces no such effect. As soon as the hydrogen has ceased, or nearly
ceased, to escape from the liquid, the solution, which consists of chloride of zinc, is carefully poured off. The residue,
together with the remnant of zinc if any tin adhere to it,
is warmed with strong chlorhydric acid, in which the tin
dissolves. Pour off this solution of protochloride of tin,
and add to it two or three drops of a solution of Test
mercuric chloride (corrosive sublimate) (~ 145).  for
A white or gray precipitate of mercurous chloride  Ill
(calomel), often mixed with gray metallic mercury will be
thrown down, for:2HgC12+SlSnlC122HgCl+-SnC1,; and
2HgCl+SlnC1  =2 Hg- +SnCl4.




42                   TABLE OF CLASS III.                  ~ 25
To prove that the precipitate really contains calomel,
decant the supernatant liquid, cover the precipitate with
ammonia-water, and heat the mixture to boiling (compare
p. 28).
The black stain upon platinum is a trustworthy indication of the presence of antimony; but a verification of its
presence may be readily obtained by the following process:-Wash the residue from the tin solution thoroughly
by decantation, and warm it for a quarter of an hour with
a solution of tartaric acid (~ 106), adding a few drops of
nitric acid towards the close of the digestion.  Care must
be taken not to heat any part of the dish so hot as to burn
or blacken the tartaric acid.
Antimony dissolves in this tartaric acid solution; its
presence may be proved by passing sulphuretted hydrogen through the decanted solution. An orange-red-colored
precipitate of sulphide of antimony will be sooner or later
thrown down.
25. An outline of the foregoing operations may be represented in tabular form, as follows:The General Reagent (H2S) of Class III precipitates As2S3,
Sb2S3, and SnS or SnS2, [AnuS.3 and PtS2].  (As well as the
members of Class II, fronl which Class III is separated by solution in sulphydrate of sodium and reprecipitation with an acid.)
Digest the precipitate, thrown down by acid from the sulphydrate
of sodium solution, in a weak solution of carbonate of ammonium:
As2S3 dissolves and    Sb2S3, SSn and SnS2 [AuS2:  and PtS.2],
may be reprecipitated  remain undissolved. Treat with HNO;3
by neutralizing  the  fuse with NaNO3; treat fused salts with
solution  with  HC1. RH0.
Confirm  presence of   Reduce the insoluble residue with zinc
As by reducing As.S:j  and dilute acid in presence of platinum
with Na2CO3- KCN.  foil. Sb is deposited on the foil. Treat
metallic residue with HC1. Sn dissolves;
its presence is proved by HgC12. Sb is
then dissolved in tartaric acid, and reprecipitated as orange Sb2 S.




~ 25       ALTERNATE METHOD FOR CLASS III.         43
Under some circumstances, acids fail to reprecipitate
completely the sulphides which are dissolved in sulphydrate of sodium. This difficulty is particularly likely to
occur when tin is present. It may be avoided by modifying the above process, as follows: add strong nitric
acid to the sulphydrate of sodiurn solution to acid reaction,
and without regard to the precipitate which separates,
evaporate the acid mixture to the bulk of one or two
teaspoonfuls. Then add three or four teaspoon-fuls of
a strong solution of nitrate of sodium, evaporate to
dryness with constant stirring, and heat the mass until
it fuses. Let the dish cool, and then soak the fused salts
in three or four teaspoonfuls of cold water, until they
soften and in part dissolve. Break up the lumps, stir repeatedly, and finally filter. Arseniate of sodium, together
with some nitrate and sulphate of sodium, passes into solution, while the antimony and tin are to be found in the
insoluble residue. This residue is examined for these two
metals precisely as above described (~ 24, p. 41).
The aqueous solution is tested for arsenic as follows:
Acidulate the solution faintly with nitric acid, and warm
it; then add a few drops of a prepared. solution of sulphate of magnesium and chloride of ammonium   Test
(~ 139), and set the mixture aside for twelve  for
hours. The formation of a white, crystalline precipitate of arseniate of ammonium  and magnesiumn is
evidence of the presence of arsenic. Any precipitate
supposed to contain arsenic or antimony may be further
examined by converting the arsenic or antimony into a
hydrogen compound, by the method known as IMarsh's
test (see the authors' 1Manual of Inorganic Chelmistry,
pp. 259, 270). This method is applicable to the detection
of very minute quantities of arsenic or antimony.
In the case of mixtures containing gold and  platinumn
(see ~ 13), as well as arsenic, antimony, and tin, the




44         SEPARATION OF CLASSES II AND III.    ~ 26
gold and platinum would remain with the tin, without
interfering in any way with the separation or detection of
either member of the class. Since the sulphides of gold
and platinum  are both black, while those of arsenic and
tin are yellow or brown, and that of antimony is orange,
the presence of any considerable quantity of either of the
precious metals would be indicated by the black color of
the class-precipitate. There are excellent special tests
both for gold and platinum, by which these elements may
be detected even in the presence of all the other metals.
Hence it is most convenient to make special search for
them in the original substance, by methods to be described hereafter (~ 92 b), whenever the preliminary examination has given reason to suspect the presence of
either of them.
26. The Method of Separating Class II fromwn Class II1
has been sufficiently described in ~~ 8, 23. Attention
should be paid to the color of the precipitate produced
when the sulphydrate of sodium  solution is acidified,
although the color of this precipitate is obscured by the
whitish mass of sulphur derived from the decomposition
of the sulphydrate of sodium itself.
An orange-colored precipitate indicates the presence of
antimony;
A bright yellow precipitate, the presence of arsenic;
A dull yellow precipitate, white at first, the presence of
bisulphide of tin; and
A dark brown precipitate, the presence of protosulphide
of tin.
A black precipitate might indicate the presence of gold
or platinum, or might be due to the presence of the
sulphide of mercury or of copper; for both these sulphides are somewhat soluble in sulphydrate of sodium in
presence of the sulphides of Class III.  (Compare ~ 43.)




~ 27                  CLASS IV.                  45
Gold and platinum must be specially sought for according
to the methods set forth in ~ 92 b.
These colorations are valuable only in so far as they
afford evidence of the presence of some one member of
the class; they by no means prove the absence of the
other members.
C IH A P T E  1  V.
CLASS IV. HYDRATES INSOLUBLE IN WATER, AMMONIAWATER, AND SOLUTIONS OF AMMONIUM-SALTS.
27. The leading fact upon which the separation of this
class is based is the insolubility of the hydrates of iron,
aluminum  and chromium  in ammonia-water, even in
presence of solutions of ammonium-salts. But these
three hydrates are not the only substances which are
liable to be precipitated in an actual analysis when ammonia-water is added in excess to a solution previously
acid. There are a number of salts, soluble in acids, but
not in water or in weak alkaline liquids, which are thrown
down as salts, without change, when their acid solvent is
destroyed.
It is clear that it is needless to provide in this place
against the presence of such salts of elements belonging
to Classes I, II, and III. Those elements are already
eliminated when the fourth class is taken in hand. But
if there are any salts of elements belonging to the fourth
and higher classes which can only be kept in solution by
a free acid, they will be precipitated without change in
consequence of the neutralization of their solvent by the
ammonia-water added to precipitate the three hydrates




46                ANALYSIS OF CLASS IV.         ~~ 28, 29
above mentioned.  Such salts are the  phosphates of
several members of Classes IV, VI, and VTII, besides a
number of oxalates, borates, silicates, and fluorides, which
occur so seldom that they need not be particularly considered in an elementary. treatise.  Beside the phosphates,
several chromites and aluminates of members of Classes
VI and VII are insoluble in ammonia-water, and are often
thrown down wholly or in part along with the legitimate
members of Class IV. Manganese also (a member of
Class V) is frequently precipitated in combination with
members of Class IV in the form of chromite, ferrite or
aluminate of manganese.  The general scheme for the exanination of Class IV necessarily provides for the detection of all the members of the class in the possible presence of these extraneous substances.
28.  Examp3le of the Precipitation with Ammonia-water.
Pour into a beaker six or eight drops of aqueous solutions of sulphate of manganese, common  alull, and
chrome-alMum,   and two or three drops of a solution of
sulphate of iron (copperas).  Dissolve in a few drops of
strong boiling ehlorhyd.ric acid as much. bone-ash as could
be held on half a pea, and add the solution to those already placed in the beaker.
Fill the beaker about one-third full of water, heat the
mixture to boiling, and add to it two or three drops of
strong nitric acid to convert the iron into sesquioxide.
Then add, little by little, aminmonia-water to the boiling
liquor until a distinct odor of aniiuonia is perceptible
after the mixture has been thoroughly stirred.
29.  Analysis of the Mixed Precipitate.  The following
method of detecting iron, chlromium-, alunminum  (and
manganese) in the mixed precipitate which: mIay contain




~ 29            ANALYSIS OF CLASS IV.             47
all of them, together with phosphates and other compounds of barium, strontium, calcium  and magnesium,
depends: —lst, Upon the sparing solubility of the oxalates of barium, strontium, calcium and magnesium  in
water acidulated with oxalic acid, and upon the ready
solubility of ferric oxide and the oxides of chromium,
aluminum and manganese in that liquid. 2d, Upon the
fact that Prussian blue is formed when a solution of ferrocyanide of potassium is added to the solution of a ferric
salt. 3d, Upon the conversion of the oxide of manganese,
chromium, or aluminum  into manganate, chromate, or
aluminate of sodium (or potassium), when fused with a
mixture of carbonate of sodium and saltpetre; and the
facts that manganate of sodium has a peculiar green, and
chromate of sodium a peculiar yellow color. 4th, That
chromate of lead is thrown clown as a bright yellow powder whlen the solution of the chromate of an alkali-metal
is added to one of acetate of lead. 5th, That hydrate of
aluminum may be isolated in the state of a peculiar flocculent precipitate.
The details of the treatment of the precipitate produced by ammonia-water, are as follows:-Collect the'
precipitate upon a filter, wash it two or three times with
water, transfer it with a spatula to a porcelain dish, pour
into the dish twice as much of an aqueous solution of
oxalic acid (~ 104) as would be sufficient to cover the precipitate, and boil the mixture during four or five minutes,
taking care to add, little by little, water enough to replace
that lost by evaporation. At last pour into the boiling
solution half its own volume of water, allow the mixture
to become cold, collect upon a filter the insoluble oxalates
(of members of Classes VI and VII) which have been
deposited, wash them  thoroughly with water, dry the
filter and its contents, and preserve them for future examination in connection with Class VI. (See ~ 39.)




48                 TEST FOR IRON.               ~ 29
Transfer a small portion of the filtrate to a test-tube,
mix with a few drops of dilute sulphuric acid, and add a
drop of a solution of ferrocyanide of potassium.  The
liquid will immediately become colored with Prussian
blue.
Evaporate the rest of the filtrate to dryness in a porcelain dish, taking care to stir the liquid constantly, so that
none of the material shall be thrown out of the dish and
lost by tumultuous boiling, and ignite the residue to destroy the oxalic acid. Take out a few grains of the residue, boil them in a little strong chlorhydric acid, then
dilute with water, and add a drop or two of ferrocyanide
of potassium to the solution. A blue precipitate falls,
Test which is a somewhat more emphatic proof of the
for  presence of iron than the blue coloration above'  described. In case much iron be present, the
blue color may be too deep to be recognized until a large
quantity of water has been poured into the tube. When
the dish has become cold, cover the residue with two or
three times its bulk of a dry mixture of equal parts of
carbonate of sodium and nitrate of potassium  (~ 128).
Rub the materials together strongly with the finger,
transfer the mixture to a piece of platinum foil, and fuse
it thoroughly in a strong oxidizing blow-pipe flame (~ 167).
In case the quantity of material be large, it may be fused
in a platinum crucible at the blast-lamp, or upon the foil,
as before, in several successive portions.
If only a manganese compound, and no chromium, had
been fused upon the foil, the cold mass would have exhibited the peculiar bluish-green color of manganate of
sodium. If only chromium had been present, the bright
yellow color of chromate of sodium  would have been
clearly perceived. But from mixtures of the manganate
and chromate of sodium, in various proportions, different




~ 29           MANGANESE AND CHIRO.MIUlA.          49
shades of green, brown-green, or yellow-green, will result.
Wlhen iron is present, the red color of its oxide may obscure the colors clue to manganese and chromium.
Place the platinum foil in a porcelain dish, cover it with
water, and boil the latter until all the soluble matter has
been dissolved from the foil. Take out the clean foil, and
throw the contents of the dish upon a filter. The insoluble
oxides of iron and manganese remain upon the filter, while
the chromate and aluminate of sodium pass into the filtrate, which is colored yellow by the chromium salt.
WVash the insoluble residue with water, allow it to
drain, and then fuse a small quLantity of it with twice its
bulk of a mixture of carbonate of sodiumn and nitrate of
potassium  upon platinum foil in the oxidizing blow-pipe
flame.  The peculiar bluish-green coloration of Test
manganate of sodium will appear in the fused  for
mass, as soon as it has become cold, particularly at Mitt
the edges and thinner portions. In thus testing for manganese, it is well to incline the foil, so that portions of
the thoroughly melted mass may flow  away from  the
centre of the mixture into thin sheets, in order that the
color of the manganate may be exhibited in its purity.
Return now to the filtrate from this insoluble residue.
Divide it into two portions. Carefully add acetic acid,
drop by drop, to one portion of the filtrate until the
liquor exhibits an acid reaction, and then add to it two or
three drops of a solution of acetate of lead  Test
(~ 137). An insoluble precipitate of chromate  for
of lead will be immediately thrown down, exhib- Cr.
iting a bright yellow color if the reagents be all pure.
But if, as often happens, the carbonate of sodium, employed as a flux, was contaminated with sulphate of
sodium, the yellow color of the precipitate will tend towards white, in proportion to the amount of sulphate of




50            SEPARrATION OF ALUMINUAM.         ~ 29
lead which has gone down together with the chromate.
A pure white precipitate would be no indication of chromium, but only of a sulphate in the  reagents.
Acidulate the other portion of the aqueous solution of
the fused sodium compounds with dilute chlorhydric acid,
add ammonia-water to slight alkaline reaction, warm the
mixture and leave it at rest for at least half an hour, or,
better, over night. After the lapse of some time, a characteristic, gelatinous, colorless agglomeration of particles
of hydrate of aluminum will appear at the top or bottom of
the liquid. It should be said, that flocks of hydrate of
aluminum, when diffused through a liquid, are almost
transparent enough to elude observation.
W7hen an acid solution, containinng much aluminum, is
mixed with ammonia-water and warmed, a copious precipitate of hydrate of aluminum will appear immediately,
and will often remain floating for some time upon the
surface of the solution by virtue of bubbles of air entangled in it. But since it is not easy to convert the
whole of the alumina in the original precipitate into
soluble aluminiate of sodium, by fusion with carbonate of
sodium in the method above described, the quantity of
the hydrate to be thrown down at the final test is often
very small, and considerable time must be allowed, in
order that every particle of it may separate from the solution, and all the particles collect into a single mass.
To confirm the presence of aluminum, collect the hydrate in the point of a small filter and allow it to drain.
Cut away the superfluous paper, place that portion of the
filter to which the precipitate is attached upon a piece of
Test charcoal, and heat it intensely in the blow-pipe
for  flame. Moisten the residue with a drop of a soA. lution of nitrate of cobalt, and again ignite it
strongly. The unfused compound of aluminum, cobalt




~g 30, 31           TABLE FOR CLASS IV..51
and oxygen, left upon the coal, will exhibit a deep sky-blue
color, when allowed to cool.  This reaction is useful in distinguishing the hydrate of aluminum from that of glucinum,
an element somewhat similar to aluminum though far less
abundant.  Hydrate of glucinum when ignited with nitrate
of cobalt does not yield a pure blue compound, but only a
gray mass.
30. An outline of the foregoing operations  may be
tabulated as follows:The General Reagent ([NH4]HO, mixed with NH4C1) of Class
IV precipitates the hydrates of Fe, Cr, and Al, together with Mn
(as a chromite, ferrite or aluminate), and various phosphates and
other compounds of Fe, Cr, Al, Ba, Sr, Ca, and Mg. Boil the
precipitate in a solution of oxalic acid:Oxalates    Oxalates of Fe, Al, Cr, and Mn go into solution.
of Ba, Sr, Test a small portion of the solution for Fe with ferCa, and Mg rocyanide of potassium. Evaporate the remainder
separate  in to dryness and ignite. Test again for Fe. Mix the
the form of residue with dry Na2CO:3 and KNO3, fuse upon plaa powder,  tinumr foil, and treat with boiling water:which is collected for future examin- Test the   Divide the solution into two portions:ation in con- insoluble
nection with  residue
Class VI.    for Mn.  Yellow color of Acidulate a portion of
aqueous solu-  the solution with HC1,
tion  indicates and add (NH4)HO:Cr. Confirm Cr Colorlessflocculent preby precipitation  cipitate proves presence
of PbCrO4.      of Al.
31. Separation of Class ITVfrom Class II.  The methods
of eliminating Classes 1, II, and III from mixtures which
contain members of these classes as well as of Class IV,
have already been described in ~~ 6 and 8.
It is essential to the success of the operation that all




52             FERROUS AND FERRIC SALTS.           ~ 31
the sulphuretted hydrogen in the filtrate from Classes II
and III be expelled, and that any iron which may be contained in the solution be converted to the state of a ferric
salt, before the genDerl reagent (NH4-,HO) of Class IV is
added to the liquid. For sulphuirettecl hydrogen precipitates all the members of Classes IV and V from alkaline solutions, and the filtrate now in question is, of
course, made alkaline, when ammonia-water is added to
it. The iron must be oxidized, because ferrous hydrate
is somewhat soluble in ammoninum-salts, and could not,
therefore, be precipitated completely by ammonia-water
from the acid filtrate from Classes II and III.
No matter wbat the condition of the iron may have
been in the original solution, it is reduced to the state of
ferrous salt by sulphuretted hydrogen. The filtrate from
the precipitate produced by sulphuretted hydrogen (the
general reagent of Classes II and III) should, therefore,
be placed in a porcelain dish, and boiled, until the steam
from it ceases to blacken lead paper (~ 138). After the
sulphuretted hydrogen has been expelled, three or four
drops of strong nitric acid must be added to the liquid,
and the mixture boiled for a moment longer to oxidize
the iron. If much iron be present, the liquid will turn
yellow.
To determine whether the iron in the substance subjected to analysis was originally in the state of a ferric or
a ferrous salt, test a small quantity of the original solution with a drop of ferricyanide of potassium  (~ 126).
The formation of Prussian blue proves the presence of a
ferrous salt. Another small portion of the original solution, tested with a drop of ferrocyanide of potassium,
would yield Prussian blue in case the solution contained
a ferric salt. In applying either of these tests, the blue
coloration, indicative of iron, is alone to be looked for;




~ 31                  CLASS IV.                    53
no notice need be taken of other colorations, or of precipitates formed by the action of the ferri- or ferro-cyanide upon the various metallic salts which the solution may
contain.  The possibility that a ferrous salt may have
been changed into a ferric salt during the process of
getting the original substance, if a solid, into solution,
must not be lost sight of.
After the iron has been oxidized, a small quantity of a
solution of chloride of ammonium is added to the boiling
liquid, and finally ammonia-water, little by little, with
constant stirring, until a persistent odor of ammonia is
perceptible. A large excess of ammonia must be carefully
avoided, for hydrate of aluminum, being somewhat soluble
in ammonia-water, might be kept in solution, to the disturbance of the analysis of Classes VI and VII.
It will be remembered that the object of using chloride
of ammonium is to hold in solution magnesium (of Class
VII) and the members of Class V. A considerable quantity of the ammonium-salt will, of course, be formed in
any event by the action of the ammonia-water upon the
chlorhydric acid in the solution, but it is best always to
add a further portion of the chloride, as a precautionary
measure.
The following inferences may be drawn from the color
of the precipitate produced by ammonia-water:A gelatinous white precipitate indicates aluminum  or
phosphate of calcium.
A grayish-green or grayish-blue precipitate indicates
chromium.
A reddish-brown precipitate indicates iron.
If no precipitate is produced by the ammonia-water, all
the members of Class IV are absent, and the solution may
at once be tested with sulphydrate of ammonium, the
general reagent of Class V.




54                      CLASS V.                   ~ 32
Wlhen the solution contains much chromium, a small
portion of this element is apt to remain dissolved at
first in the excess of ammlonia-water, and to color the
solution pink; but by continuing to boil the solution, the
color may be made to disappear, and the whole of the
chromnium  thrown down.  Care must be taken to replace,
by smaall portions, the water driven off by boiling, lest
some of the members of Class V be rendered insoluble.
It is to be observed that the legitimate rnembers of
Class IV cannot be completely precipitated by ammoniawater from  solutions which contain non-volatile organic
substances, like albumen, sugar, starch, and so forth, or
organic acids (such as tartaric, citric, oxalic, or even in
some cases acetic acid) which form soluble double salts by
uniting simultaneously with the ammlonium  and one or
more of the members of the class. The treatment of
substances containing org anic matter will be explained
hereafter. (~ 76, I.)
CHAPTER YI.
CLASS V. SULPIHIDES INSOLUBLE IN WATER AND IN
SALINE OR ALKALINE SOLUTIONS.
32. EvraLple of the Precipitation of the Members of Class
V. Place in a small glass flask six or eight drops of stroing
aqueous solutions of the sulphates, nitrates, or chlorides
of cobalt, nickel, mlanganese and zinc. Add to the mixture five or six teaspoonfuls of a solution of chloride of
animonium, twice as much water, and ammonia-water to
alkaline reaction.
HIeat the mixture to boiling, and add sulphydrate of




~ 33              ANALYSIS OF CLASS V.                55
ammoniumn to the boiling solution, drop by drop, with
frequent agitation, as long' as a precipitate continues to
be formed.  (Comnpare p. 33.)  In the present case there
are special reasons why the precipitate should be boiled
and shaken, in order to mnake it compact; for the sulphides of Class Y, when loose and fiocculent, are not
only easily acted upon by the air ancd by dilute acids, but
are peculiarly liable to pass through the pores of filterpaper and yield muddy filtrates.
At the best, these sulphides oxidize rapidly when moist,
with formation of soluble sulphates which are liable to
pass through the filters and contaminate the filtrates.
The analysis of the sulphides should therefore be proceeded with immediately after the precipitation with sulphydrate of ammonium, and should be conducted in such
manner that no precipitate of a sulphide shall ever be
left moist upon a filter more than half an hour.
33. Analysi.s of the Mixed Satlphides.  The detection of
the several members of Class V depends, Ist, Upon the
almost complete insolubility of the sulphides of cobaltand nickel in cold dilute chlorhydric acid, and the ready
solubility of the sulphides of manganese and zinc in that
liquid.  2d, Upon the solubility of hydrate of zinc, and
the insolubility of hydrate of manganese, in a solution of
caustic soda. 3d, Upon the insolubility of sulphide of
zinc in alkaline solutions. 4th, Upon the peculiar colors
imparted to borax glass by compounds of cobalt and
nickel dissolved in the glass; and upon certain other special tests to be described directly.
To effect the separation:-Collect the precipitate upon
a filter, and rinse it once or twice with water; spread
open the filter in a porcelain dish, and cover it with cold
dilute chlorhydric acid.  Scarcely any of the sulphide of




56                ANALYSIS OF CMASS V.               ~ 33
cobalt, or of nickel, will go into solution, while the sulphides of manganese and zinc will be completely decomposed, and dissolved as chlorides.
Filter the chllorhydric acid solution, pour the filtrate
into a porcelain dish, anld boil it, until strips of moistened
lead paper held in the steam no longer indicate the presence of sulphuretted hydrogen; then transfer the liquid
to a beaker or test-tube, and add caustic soda  (~ 116)
to it in slight excess.  A whitish gelatinous precipitate of
hydrate of manganese, insoluble in caustic soda, will be
thrown down, together with small portions of the hydrates
of cobalt and nickel (partieu7larly the latter), resulting
from the partial decomposition of the sulphides of these
metals by the eliorhydaric acid, while the hydrate of zinc
at first precipitated redissolves completely in the excess
of soda. It is to be observed that precipitation should
never be effected in a porcelain dish, since a white or
transparent precipitate is scarcely visible in a white and
opaque dish.
To prove the presence of manganese, collect the precipitate upon a filter, allow it to drain, and fuse a simall
portion of it with a mixture of carbonate of sodciun and
nitrate of potassium upon pl;atinumn foil in the oxicdizing
blow-pipe flame, as directed on p. 49.
Through the alkaline filtrate pass sulphuraetted hydrogen gas.  Sulphide of zinc will be thro-wn down as white
or dirty-white floculent p:reeipita-e.
To confirm the presence of zinc:-Collect the precipitate produced by sulphuret-ted hydrogen upon a filter
and allow to drain; transfer it to a porcelain dish, dissolve it in dilute ehlorhydric acid, and evaporate the solution almost to dryness on a water-bath (~ 166). Dissolve
the residue in a few drops of water, and without heediing
the milkiness which the presence of particles of free




~ 33           ZINC, NICIEL, AND COBALT.          57
sulphur nmay produce in it, pour this liquid into a testtube containing two or three teaspoonfuls of a solution
of normal chromate of potassium previously heated to
boiling. A peculiar yellow, somewhat flocculent Test
precipitate of basic chromate of zinc will be  for
formed in the boiling liquid, and will soon sub-  ll"'
side to the bottom of the tube. The red color of the
supernatant fluid is due to the formation of bichromate
of potassium.
It is to be observed that in the analysis of mixtures
which contain no manganese, the precipitate of hydrate
of cobalt or of nickel, produced by the caustic soda, is
usually small and sometimes hardly perceptible; but, no
matter how minute the precipitate may be, it must always
be carefully removed by filtration before testing the solution for zinc with sulphuretted hydrogen.
The black residue, insoluble in dilute chlorhydric acid,
is washed with water and tested for cobalt and nickel, by
heating successive small portions of it in a bead (~ 84,
c.) of borax (~ 119) in the oxidizing' blow-pipe  Tests
flame. If cobalt alone were present, a bright,  for
pure blue color would be imparted to the bead. Co &  -.
On the other hand, if the precipitate was composed solely
of sulphide of nickel, the borax glass would assume a
peculiar reddish-brown color. Mixtures of the two sulphides yield beads of various tints, according to the proportions of nickel and cobalt contained in them. By
adding the precipitate to the borax by repeated small
portions, and fusing the bead anew after each addition, it
is often possible to obtain first the characteristic color of
one of the elements and afterwards tolerably well defined
indications of the other.
The blue color of cobalt can usually be made manifest,
even in presence of much nickel, by heating the borax




58              SEPARATION OF NICKEL.             ~ 33
bead in the reducing blow-pipe flame (~ 167).  In the
reducing flame the reddish-brown color imparted by
nickel changes to gray, while the cobalt blue remains
unnaltered.
In any event, one of the two metals will be detected by
the blow-pipe test, and the subsequent operations can be
limited to searching for the other.
To prove the presence of nickel, boil the black residue
with a few drops of aqua regia in the porcelain dish, and
evaporate the solution almost, but not quite, to dryness.
Add to the residual acid liquor, little by little, a strong
solution of cyanide of potassium, until the reaction of the
solution becomes decidedly alkaline, and boil the mixture
for five minutes, taking care to add water by small portions to fully replace that lost by evaporation. The
cyanides of nickel and cobalt, at first thrown clown, both
redissolve easily in an excess of cyanide of potassium;
but while the cyanide of nickel undergoes no change
when the mixture is boiled, the cyanide of cobalt is all
converted into cobalticyanide of potassium, and from solutions of this compound, cyanide of cobalt is not precipitated on the addition of acids.
As soon as the liquid has become cold, pour dilute sulphuric acid into it, without heeding any precipitate which
may have formed during the evaporation, until a drop of
the mixture turns blue litmus-paper red. Transfer the
acidulated liquor to a large test-tube, fill the latter with
water, shake the mixture well, and allow it to stand durTest ing eighteen or twenty-four hours. The soluble
for  compound of cyanide of nickel and cyanide of
i'  potassium is decomposed by the sulphuric acid,
and the cyanide of nickel precipitated in the form of a
light, dirty greenish-yellow powder, which slowly subsides to the bottom of the tube.




~ 34             SEPARATION OF COBALT.              59
Sometimes a dark layer of dirt, derived from impuarities
in the reagents, is deposited above or below the str'atum
of cyanide of nickel, but it seldom happens that thle characteristic color of the latter is materially obscured by
this contamlnation. At other tiines, when the operations
have been performed carelessly, and the reagents have
been employed in uncldue cquantities, crystals of sulphate
of potassium will separate in the tube; but they can
readily be removed by dissolving them in water.
To confirm the presence of cobalt in case of doubt:Dissolve the black residue in a few ldrops of hot aqua
regia, evaporate the solution nearly to dryness, pour into
the residual solution two or three times its own volume
of a solution of nitrite of potassium (~ 129), and add to
the mixture concentrated acetic acid, until the reaction
of the liquid is strongly acid. Transfer the mix- Test
ture to a test-tube, and leave it at rest during   for
eighteen or twenty-four hours. A beautiful, yel- Ca
low crystalline precipitate of the double nitrite of cobalt
and potassium will be deposited sooner or later, according to the proportion of cobalt which the solution contained.
On adding caustic soda to the filtrate from the yellow
cobalt precipitate, hydrate of nickel would be thrown
down if it were present, and the presence of nickel might
be confirmed by testing this precipitate with borax in the
oxidizing blow-pipe flame.
34. An outline of the foregoing operations may be
tabulated as follows:



60                 TABLE FOR CLASS V.                  ~ 35
The General Reafgent ([N4]IIHS) of Class V precipitates CoS,
NiS, T1MnS, and ZnS. Treat the precipitate with dilute HOC1:CoS and NiS I MknCl, and ZnCl2 go into solution. IBoil, to exremain undis- pel H2S, and add NaHO:solved.
Test for Co
and Ni with   Hydrate of manganese   Hydrna,3te of zinc goes
borax  glass, is precipitated, together into solution. Add H12S
and, if need with traces of the hy- to throw down ZnS.
be, with KCN  drates of Co and Ni.    Confirm  presence of
or KiNO2.      Prove presence of Mln zinc by precipitation of
by the blow-pipe test.   the chromate.
35. Separation of Class   fBrom Class I. After Classes
1, II, III, and IV  have been removed iz the manner
already described (~~ 9, 31), add a single drop of sulphydrate of ammonium of good quality (~ 110) to the filtrate
from  Class IV. If no precipitate is produced, none of
the memnbers of Class V can be present, and the solution
may be immediately tested with carbonate of anmlaonium,
the general reagent of Class VI.
If the first drop of the suiphydrate produces a precipitate, transfer the mlixture to a small flask, heat it until it
actually boils, and add more of the sulphydrate, with the
precautions enjoined on p. 55 to complete the precipitation.
In case the precipitate produced by sulphydrate of
ammonium be white, the presence of zinc is indicated.
If it be flesh-colored or yellowish-white, and become
brown by oxidation when exposed to the air, the presence
of manganese is to be inferred.
In case the precipitate is black, either cobalt or nickel,
or both these elements, are present.  Both of them must
be sought for, whenever the precipitate exhibits any tinge
of black at the moment of its formation.




~~ 36, 37               CLASS VI.                     61
CHAPTER VII.
CLASS VI. CARBONATES INSOLUBLE IN WATER, AMXXONIAWATER, AND SALINE SOLUTIONS.
36. Exarmple of the Preeiitation of thfie Members of Class
VI. Place in a test-tube six or eight drops of strong
aqueous solutions of the chlorides or nitrates of barium,
strontium, and calcium. Add to the mixture two or three
teaspoonfuls of a solution of chloride of ammonium,
enough ammonia-water to produe an alkaline reaction,
and finally a solution of carbonate of ammonium, drop
by drop, as long as any precipitate continues to be produced by fresh portions of this reagent. To determine
this last point, heat the mixture to boiling at intervals,
and after boiling allow- it to settle, until a sufficient quantity of comparatively clear liquid has collected at the top
of the mixture to permit the application of the test
37. Analysis of the  Mixed Carbonates. The separation
of barium, strontium  and calcium, one from the other,
depends:-lst, Upon the insolubility of chromiate of
barium  in dilute acetic acid, and the solubility of the
chromates of strontium and calcium in that liquid. 2nd,
Upon the fact that sulphate of strontium. is almost absolutely insoluble in acidulated water, while sulphate of calcium, though rather sparingly soluble in water, is still
sufficiently soluble to be kept in solution.  (See ~ 123.)
Collect the precipitate upon a filter, wash it two or
three times with water, taking care to collect the precipitate at the apex of the filter, and dissolve it in acetic
acid. The acid may be poured into the filter as it rests
4




62                 TEST FOR BARIUM.                ~ 37
in the funnel, but only a moderate quantity should be used,
and the filtrate should be poured back upon the filter,
until the acid is saturated. Finally rinse the filter with
a little water from  a wash-bottle with small orifice,
collect the wash-water with the filtrate, and shake the
mixture.
Pour a small portion of the acetic acid solution into a
test-tube, and add to it a drop of a solution of normal
chromate of potassium. A pale yellow precipitate falls
Test when barium  is present, as in this instance; for
for  chromate of barium  is well nigh insoluble in
B~ a.acetic acid, especially in presence of saline solutions. In order to separate the whole of the barium, pour
the contents of the test-tube into the reserved portion of
the acetic acid solution, heat the mixture to boiling, and
add to it chromate of potassium, until no more precipitate
falls and the supernatant liquor appears distinctly colored,
after having been well shaken and allowed to settle.
Filter the mixture, and proceed to examine the filtrate
for strontium and calcium.
If no barium had been present, no precipitate would
hlave been produced by chromate of potassium  in the
small portion of liquid first tested, and it would have been
unnecessary to mix this reagent with the rest of the acetic
acid solution  Trouble would thus be saved, as will appear below.
It sometimes happens that chromate of barium is precipitated in the form of powder so fine that some particles
of it pass through the pores of the paper and contaminate
the filtrate. Now, in order to detect strontium  and calcium, it is absolutely necessary that this filtrate, although
of a bright yellow color, should be perfectly transparent
and free from suspended particles of the barium salt. If
then the filtrate is at all t'ubid, it must be poured back




~ 37       TESTS FOR STRONTIUM AND CALCIUM.        63
repeatedly into the filter, and again collected in clean
tubes, until the last trace of cloudiness has disappeared.
To the filtrate from the chromate of barium add ammonia-water to alkaline reaction, and carbonate of ammonium as long as a precipitate falls. Heat the mixture
to boiling for a moment, collect the precipitate upon a
small filter, and wash it with water, until all the chromate
of potassium has been removed, and the wash-water runs
colorless from the filter.
Dissolve the precipitate in the smallest possible quantity
of acetic acid, and mix it with three or four times its
volume of a solution of sulphate of potassium (~ 123),
made of such strength that, though capable of throwing
down sulphate of strontium, it cannot precipitate sulphate
of calcium. Allow the mixture to stand at rest Tests
for two hours or more, in order that the white  for
powder of sulphate of strontium  may separate Sr. & Ca.
completely. Then filter, and to the filtrate add ammoniawater to alkaline reaction, and half a teaspoonful of a solution of oxalate of ammonium (~ 113). A white precipitate of oxalate of calcium will be immediately thrown
down.
Since sulphate of strontium is somewhat soluble in a
solution of chromate of potassium, the filtrate from
chromate of barium cannot be examined directly for
strontium  by means of sulphate of potassium.  The
strontium and calcium are consequently reprecipitated as
carbonates, in order that the excess of chromate of potassium may be washed away. The operation serves also to
collect the strontium and calcium out of the mass of liquid
in which they have become diffused, and to concentrate
them to a small bulk.
It should be observed that, when the proportion of




64                 TABLE FOR CLASS VI.           ~~ 38, 39
strontium  or calcium  in a mixture is small, it often
happens that the precipitate, produced by carbonate of
ammonium in the filtrate from chromate of barium, is held
in suspension, and concealed so completely in the yellow
liquor, that an unpractised eye can hardly detect the fact
that the liquid has become cloudy. That a precipitate has
really been formed in such cases is easily discovered by
throwing a portion of the mixture upon a filter, and comparing the clear filtrate thus obtained with that portion
of the mixture which has been left unfiltered.
38. An outline of the foregoing operations may be
presented in tabular form, as follows:The General Reagent ([NH,4]2CO3) of Class VI, precipitates the
carbonates of Ba, Sr, and Ca. Dissolve in dilate acetic acid, and
add K2CrO4:BaCrO4   SrCrO4 and CaCrO4 remain in solution.  Add
is thrown (NH4)2C03 and (NH4)HO.  Collect and wash the
down as precipitate, and dissolve it in acetic acid. Add dilute
a yellow K2S04:
powder.
SrS04 is   CaS04 remains in solution. Add oxalate
thrown of ammonium, to precipitate oxalate of caldown.   cium.
39. Separation of Class VI from  the Preceding Classes.
After Classes I, II, III, IV and V have been separated in
the manner already described (~~ 6 to 10), there will still
always remain to be examined the filtrate from Class V,
and sometimes a precipitate (~ 29) composed of oxalates
of barium, strontium, calcium  and magnesium,-in case
any  salt of these  elements, insoluble  in  ammoniawater, has been thrown down with  the members of
Class IV.




~ 39           SEPARATION OF CLASS VI.           65
If such a precipitate has been obtained in the analysis
of Class IV, the oxalic acid contained in it must now be
destroyed, the remainder of the precipitate brought into
solution, and this solution added to the filtrate firom
Class V, before proceeding to precipitate the members of
Class VI. To this end, ignite the dry precipitate carefully
upon platinum foil-by several successive portions if the
precipitate is large, —taking care that none of the powder
is left sticking to the paper or lost by dropping it from
the foil. At a moderate heat the oxalates suffer decomposition, and only carbonates or oxides are left upon the
foil. Place the foil and the residue in a small porcelain
dish, and dissolve the residue in boiling dilute chlorhydric
acid. Add a few drops of chloride of ammonium to the
solution, neutralize the acid with ammonia-water, pour
the liquid upon a small filter and add the filtrate to that
obtained from Class V. Then add a solution of carbonate
of ammonium to the mixture, and boil it in the manner
described in ~ 36.
If there be no precipitate of the oxalates from Class IV,
the filtrate from Class V will, of course, be treated directly
with carbonate of ammonium, care being taken to add
only a drop or two of the reagent, at first, to ascertain
whether any of the members of Class VI are really contained in the solution.
The solution to which the general reagent carbonate of
ammonium is added, must contain chloride of ammonium,
to prevent the precipitation of magnesium as a carbonate,
and also ammonia-water, to hinder the decomposition of
the carbonates of barium, strontium and calcium, by the
boiling chloride of ammoniumn. But since the excess of
ammonia-water and the chloride of ammonium, added
to the solution before the separation of Class IV, are still




66              SEPARATION OF CLASS VI.           ~ 39
contained in it, no new quantity of either of them need
here be added.
It is to be remembered, in this connection, that the
carbonates of barium, strontium  and calcium, are all
slightly soluble in a solution of chloride of ammonium,
and that no precipitate whatever is produced when carbonate of ammonium is added to a weak solution of either
of the members of Class VI, in case a large quantity
of chloride of ammonium  has been previously mixed
with it.
In a solution containing traces of barium or strontium
these elements might fail to be detected, in case the chlorhydric acid employed in the process of separating Classes
I and II was contaminated with sulphuric acid, or in case
the original liquid contained nitric acid to oxidize a portion of the sulphur of the sulphuretted hydrogen employed
to precipitate Class II, or even if the nitric acid, employed
to oxidize iron in the filtrate fronm Classes II and III,
were added before the sulphuretted hydrogen had been
expelled. All danger could be avoided, however, by using
pure chlorhydric acid to precipitate Class I, and expelling
the nitric acid from the filtrate by evaporating the latter
to dryness upon a water-bath, covering the residue with
pure concentrated chlorhydric acid, again evaporating
until the mixture became dry, and finally dissolving in
acidulated wate3r.




~~ 40, 41            CLASS VII.                 6
CHAPTER VIII.
CLASS VI. —INCLUDES THE REMAINING COMMON ELEMENTS NOT COMPRISED IN THE PRECEDING CLASSES, NAMELY: MAGNESIUM, SODIUM AND POTASSIUM.
40. The detection of the Several Members of Class VII
depends:-ist, Upon the insolubility of a double phosphate of magnesium and alnmonium, and the solubility of
the phosphates of potassium and of sodium; and 2d, Upon
the facts that compounds of sodium and potassium impart
peculiar colorations to non-luminous flames, like those of
alcohol and of a mixture of coal-gas and air.
Prepare a mixture of ten or twelve drops of strong
solutions of almnost any one of the salts of magnesium,
sodium and potassium, and add to the mixture an equal
bulk of chloride of ammonium. Pour a quarter of the
mixture into a test-tube and the remainder into a small
porcelain dish. Add to the contents of the test-tube two
or three drops of a solution of diphosphate of sodium
(~ 121), and as much ammonia-water, and shake the cold
mixture at frequent intervals during one or two hours.
A crystalline, white precipitate of phosphate of  Test
magnesium and ammonium will appear after a  for
longer or shorter interval, according as the original solution was more or less dilute.
41. Evaporate the contents of the porcelain dish to
dryness, ignite the residue until the chloride of ammonium
has been completely expelled-a point which will be indicated by the cessation of fuming-allow the dish to
cool, and pour into it three or four drops of water.




68          TESTS FOR SODIUM AND POTASSIUM.       ~ 41
Carefully clean the loop on a piece of platinnm  wire by
washing it repeatedly with water, and finally holding it in
the lamp flame until the last traces of sodium compounds
are burned off, and it ceases to color the flame. W~ithout
touching the loop with the fingers, dip it into the aqueous
solution in the dish, and again hold it in the flame. A
Test  bright yellow color will be imparted to the flame
for  by the sodium contained in the mixture; but the
NM. color peculiar to potassium compounds will be invisible, since the yellow color of the sodium' overpowers
and conceals it. Dip the loop a second time in the solution, and again hold it in the lamp flame; but this time
look at the flame through a piece of deep-blue cobalt
glass. This cobalt glass is the ordinary blue glass used
for stained glass windows; it is essential that the glass
should be of moderate thickness, and colored blue
Test  throughout, not simply "flashed" with blue.  The
for  characteristic violet color imparted to flame by
Ad  potassium compounds will now be visible, for the
blue glass shuts off completely the yellow sodiul  light,
while it permits the free passage of the violet rays.
Since traces of compounds of sodium and potassium
are to be found almost everywhere, it is sometimes difficult to determine by the foregoing tests whether the
substance under examination contains one or other of
these elements as an essential ingredient, or merely as an
accidental impurity. It is always possible, however, to
separate the sodium  or the potassium  from  the other
members of the class, and to decide, by actual inspection
of the isolated compounds, whether one or both of these
substances is contained in really appreciable quantity in
the substance subjected to analysis. If only potassium is
sought for, filter the aqueous solution, last mentioned,
through a very small filter, add to the filtrate a drop or




~ 41           REMOVALT Or MAGNESIUM.            69
two of chlorhydric acid and several drops of a solution of
bichloride of platinum (~ 146). A yellow crystalline precipitate of chloroplatinate of potassium will separate after
some time. Since chloride of ammonium would produce
a similar precipitate, it is, of course, essential that the ammoniacal salt should be expelled by ignition before potassium can be tested for.
In case sodium, or both sodium and potassium, be
sought for, the magnesium must first be got rid of. To
this end, moisten the dry residue, which contains the
chlorides of magnesium, of potassium  and of sodium,.
with a drop or two of water, mix it thoroughly with an
equal bulk of red oxide of mercury, and ignite the mixture until fuming ceases. The chloride of magnesium
will be changed to oxide, while the easily volatile chloride
of mercury escapes:MgC12-+HgO=MgOH —     geCl2~
The ignition should be effected beneath a chimney, or
in a draught of air powerful enough to carry away the
poisonous fumes of the corrosive sublimate.  Boil the
ignited residue with a small quantity of water; separate
the insoluble oxide of magnesium, together with the
excess of oxide of mercury, by filtration; evaporate the
filtrate to a small bulk; throw down the potassium as
chloroplatinate, collect the latter upon a filter, and from
the filtrate remove the excess of chloride of platinum by
means of sulpliuretted hydrogen. Filter off the sulphide
of platinum, and evaporate the filtrate to dryness to obtain the chloride of sodium. Or, instead of employing
sulphuretted hydrogen, evaporate the filtrate from chloroplatinate of potassium in a watch glass, at a gentle heat,
until the liquid begins to become dry at its edges, and
4*




70             ISOLATION OF CLASS VII.       ~~ 42, 43
then examine it with a magnifying glass. Characteristic
crystals of chloroplatinate of sodium will be seen in the
form  of long, slender prisms or needles of yellow color.
42. The Isolation of Class VII, by the removal of the
preceding classes, has been described in ~ 12. Care must
always be taken to concentrate the whole of the filtrate
from Class VI by evaporation, before testing a portion of
it for magnesium; and time enough must be allowed for
the magnesium precipitate to crystallize. The remainder
of the filtrate from  Class VI must be evaporated to
dryness and ignited, before testing for sodium and potassium, in order that the flame reactions of these elements
may not be concealed or obscured by the vapors of ammonium-salts, or the combustion of particles of organic
matter derived from the various reagents which have been
added in the course of the analysis.
43. An outline of the methods employed for separating the several classes is presented in tabular form on
the opposite page. The method of separating Class III
from Class II must be slightly modified when mercury is
present in the form of a mercuric salt. Sulphydrate of
ammonium should in that case be substituted for sulphydrate of sodium; because the sulphide of mercury is
rather soluble in sulphydrate of sodium. The presence
of mercury will generally be made known during the
preliminary examination (~ 76, III, c.).  Sulphide of
copper also is somewhat soluble in the sulphydrates of
sodium  and ammonium, in presence of the sulphides of
Class III; but enough of this sulphide will always
remain undissolved to insure the detection of copper in
Class II.
Since sulphydrate of ammonium often fails to dissolve




TABLE FOR THE SEPARATION OF THE SEVEN CLASSES OF THE METALLIC ELEMENTS.                             A
Add an excess of dilute HIC1 to the solution to be examined.
Saturate the filtrate with H2S.
a- S?.Boil the precipitate   Boil the filtrate, to expel H2S, and add HN03, to oxidize Fe. Then add
CDg c-    with NaHS.       NH4C1 and a slight excess of NH4HO.
r. To the alkaline   A precip-  To the filtrate add a drop of NH4FHS.
r filtrate add an  itate indi- 
Pb.    excess of HC1.  cates
IAg                                     A precip-  To the filtrate add a drop of (N]H4)2CO3.            o
CHg   D       -                     itate indi- 
A precipitate    Fe       cates
HS Eg   indicates       Cr                   A precip-   Evaporate the residual liquor to a      m
(See   Pb                      Al         Co      itate indi-  small bulk, and test a portion of it for
~ 17.)  Bi        As          3CaO,        Ni      cates       Mg (see ~ 40).
Cd        Sb           P205        Mn                    Evaporate the rest of the solution to
Cu        Sn            etc.       Zn          Ba      dryness; ignite and test for Na and K
[Au                                  Sr      (see ~ 41).
(See       Pt]       (See ~ 29.)  (See ~ 33.)  Ca
~20.)
(See ~~ 24, 43.)                      (See ~ 37.)




72             NON-MIETALLIC ELEMENTS.           ~ 44
sulphide of tin, it is not, in general, so fit a solvent for
the sulphides of Class III as sulphydrate of sodium.
CHAPTEIR IX.
GENERAL TESTS FOR THE NON-METALLIC ELEMENTS.
44. The following common elements remain to be
considered:-Sulphur, nitrogen, phosphorus, carbon,
boron, silicon, chlorine, bromine, iodine, fluorine, oxygen,
hydrogen. It is obvious that oxygen and hydrogen eannot be directly sought for by any analytical process conducted in the wet way. These elements are added to the
original matter in the water which is used as a solventThe presence of these elements is either inferred from
the other results of the analysis, or forms the object of
direct inquiry in the prelirminary treatment-that important
part of every analysis which forms the main subject of
Part II. The remaining elements all belong to that class
vaguely described as non-metallic; they unite with oxygen,
hydrogen, or both these elements, to form what are commonly called acids.
As the metallic elements are recognized through familiar compounds, oxides, chlorides, sulphides, or other,
so these non-metallic elements are identified by working
out of the unknown mixture their characteristic compounds.  These compounds are generally salts.  But
there is one marked difference between the search for the
metallic and the search for the non-metallic elements in
the wet way. In connection with the determination of a
metallic element, no question usually arises except the
fundamental one of its presence or absence in a given




~ 44           METAL FIRST SOUGHT FOR.            73
solution.  The sodium in the three different salts, sulphate, sulphite and hyposulphite of sodium, for example,
is detected in one and the same method; but, when the
other elements of these salts are sought for, three different reactions will occur, according to the varying nature
of the ingredients other than sodium. A sulphate in
solution gives one set of reactions, a sulphite another,
and a hyposulphite a third. It is important to do more
than  determine  the mere presence of sulphur and
oxygen. We want to know whether the sodium salt be a
sulphate, sulphite, or hyposulphite. Analogous questions
arise with regard to other non-metallic elements; there
is chlorine both in chlorides and chlorates, and carbon
both in carbonates and oxalates. Arsenic, too, may be
present in the form of arsenite or arseniate, and these
two different kinds of salts exhibit many quite dissimilar
reactions.
The examination into the nature of the other ingredients of any compound is invariably subsequent to the
determination of the metallic element or elements by the
method detailed in the preceding chapters. In the language of the dualistic theory, when the base has been
found, the acid is sought for. By whatever words the
object of the analyst be described, the process itself is in
general as follows:-The analyst tries to identify each
class of salts by precipitating, or otherwise making manifest, some familiar member of that class. Thus he identifies sulphates by precipitating sulphate of barium, chlorides by precipitating chloride of silver, carbonates by
throwing down carbonate of calcium, and so forth. The
practically important inquiry is, how to find means of
identifying each of the principal classes or kinds of salts.
The word " class " or " kind " of salts is used in this connection as a collective name for all the salts from which




74                 GENERAL REACTIONS.               ~ 44
the same acid may be derived, or which, in dualistic language, "contain" the same acid: thus all sulphates constitute one class or kind, all carbonates another, and so
forth.  The following common classes of salts are those
for which more or less perfect means of recognition will
be given in this chapter:-Sulphates, sulphites, hyposulphites, sulphides, arseniates, arsenites, phosphates, carbonates, oxalates, tartrates, borates, silicates, chromates,
fluorides, chlorides, bromides, iodides, cyanides, nitrates,
chlorates, acetates.
-No system of successive testing and elimination, analogous to that already described for the metallic elements,
has been devised for the non-metallic constituents of
salts. There are, indeed, certain so called general reagents
for acids; but these reagents are chiefly useful to show
the simultaneous presence or absence of members of
several classes of salts, and hardly help towards the identification of any individual class, except in cases of the
simplest sort in which only a single class of salts is represented.
The knowledge of the metallic element or elements
present, previously gained, is usually a great help in the
determination of the other constituents. A single example will illustrate sufficiently for our present purpose this
important principle, which is of very wide application in
qualitative analysis.  Suppose calcium to have been found
in an aqueous solution of various salts; it is directly to be
inferred with great confidence, though not with entire certainty, for example, that there is no sulphate, phosphate,
silicate, carbonate, oxalate, or tartrate in the original
liquid, since these calcium  salts are insoluble in water;
that, in short, the greater number of the classes of salts
above enumerated are absent. The list of salts excluded
by the demonstrated presence of calcium would be very




~ 45               THE BARIUM TEST.                 75
long. So it is in greater or less degree with many other
metallic elements. It is, indeed, no easy matter to make
a solution containing even one representative of the seven
classes into which the metallic elements have been
divided, because each of these elements, except sodium
and potassium, present in solution excludes one or more
whole classes of salts. By attending to the just inferences to be drawn from the quality of the metallic elements, much time will be saved, and the want of a
systematic procedure in searching for the non-metallic
elements will be little felt. The presence of the arsenites
and arseniates, of chromates, sulphides, sulphites, and
hyposulphites will ordinarily be revealed in the course of
the search for the metallic element.
Before giving the special tests by which the abovementioned classes of salts are identified, we proceed to
describe certain general tests which are of value, particularly when they give negative results.
45.  The Barium  Test. When a solution of chloride
(or nitrate) of barium is added in suitable quantity to a
neutral or slightly alkaline solution containing representatives of any or all of the following classes of salts, precipitation usually occurs, for all these salts of barium are
insoluble in water and alkaline liquids, if no ammoniumsalts be present:
Sulphates,        Arseniates,       Tartrates,
Sulphites,        Arsenites,        Borates,
Hyposulphites,    Carbonates,       Silicates,
Phosphates,       Oxalates,         Chromates,
Fluorides.
If the chloride (or nitrate) of barium fail to produce a
precipitate under the prescribed conditions, the complete




76                THE BARIUM TEST.                ~ 46
absence of all the above thirteen classes of salts is at once
demonstrated, provided that no ammonium-salts be contained in the original solution.
43. Illustration of the Barium Test. Prepare in a testtube a solution containing at once sulphate, phosphate,
and carbonate of sodium; a very small bit of each salt
will be sufficient.  The solution will be found to be
alkaline to litmus paper. Add to it chloride of barium
(~ 135), little by little, until a fresh addition of the reagent no longer produces an additional precipitate. The
white precipitate consists of sulphate, phosphate and carbonate of barium. All the thirteen barium salts which
are liable to precipitation under these circumstances are
white, with the single exception of chromate of barium.
The yellow color of the chromate of barium (~ 36) distinguishes this one precipitate from all the rest. If this
color is well marked, the presence of a chromate in the
original solution (which must also have been yellow) may
be inferred with certainty. In all other cases, however,
the precipitate is white, as in the present experiment.
The next question is, can anything further be learned
from this white precipitate?
Add to the contents of the test-tube dilute chlorhydric
acid, until the liquid has a decidedly acid reaction to
litmus paper. An effervescence indicates the escape of
carbonic acid, displaced by the less volatile chlorhydrie
acid. The bulky precipitate which the chloride of barium
produced will in part disappear, but a portion of it
remains undissolved. Filter the contents of the tube.
The particles of precipitated sulphate of barium are so
very fine that they often pass through the pores of the
paper, necessitating repeated filtration through the same
filter. To the filtrate add ammonia-water until the liquid




~ 46              THE BARIUM TEST.                 77
has an alkaline reaction. A precipitate will reappear.
Of all the barium salts which may be precipitated under
these circumstances, only one, the sulphate of barium,
is insoluble in chlorhydric and other strong acids.  A
separation of sulphur from a hyposulphite will not be
mistaken for a barium precipitate (~ 22, p. 37). The
fact that any of the original precipitate remains undissolved by the chlorhydric acid demonstrates the presence
of a sulphate. The portion of the original precipitate
which dissolved in the acid, and was reprecipitated by
ammonia, consisted in this particular experiment of phosphate of barium; but in an actual analysis the possible
salts represented would be so numerous as to make the
indication of but little value.
If ammonia-water should cause no reprecipitation in
the acid liquid which was filtered from the original precipitate, it must not be inferred that the acid of course
dissolved nothing. The borate, oxalate, arseniate, arsenite, tartrate and fluoride of barium  are all moderately
soluble in solutions of ammoniacal salts, and may not be
precipitated on the addition of ammonia. Of course, if
the original solution contained ammonium-salts, these
six barium salts, if present in small quantity only, might
fail to be precipitated. In fact, all the thirteen abovementioned barium salts, except the sulphate, are more or
less soluble in solutions of ammonium-salts, so that whenever these ammonium-salts are known to be present,
there is really but one perfectly satisfactory indication
with chloride of barium. The presence of a sulphate is
revealed by it with certainty, but the results of the other
tests must be received with some distrust. If the original
solution be acid, it is necessary to neutralize it with ammonia-water before the chloride of barium  is added.
Sometimes a precipitate is produced by the ammonia



78                 THE CALCIUM TEST.               ~ 47
water so added; in that case it is necessary to filter and
proceed with the filtrate, although the ammonia-water
may have thrown down salts of several of the classes
above named, such as phosphates, oxalates, and fluorides.
Even if the ammonia-water produce no precipitate, the
testing is then performed under the disadvantage of the
presence of ammonium-salts.
If the original solution contained silver or lead salts,
or mercurous salts, it would be impossible to use chloride
of barium and chlorhydric acid as reagents; they would
throw  down the chlorides of those metals. Nitrate of
barium (~ 136) and dilute nitric acid must then be used.
The acids added to the precipitate formed by the barium
salt must be always dilute acids. Chloride and nitrate of
barium are themselves insoluble in concentrated chlorhydric and nitric acids, and if a strong acid were used as a
solvent, the reagent salt might itself separate fi-om the
liquid.
47. The Calcium  Test. Chloride (or nitrate) of calcium
precipitates the same classes of salts as chloride (or
nitrate) of barium, with the single exception of the chromates. When sulphates and all ammoniacal salts are absent,
or present only in minute quantities, something may be
learned by testing a neutral or slightly alkaline solution
supposed to contain representatives of some of the other
classes of salts enumerated in ~ 45, with chloride or
nitrate of calcium. The calcium salts liable to precipitation under these circumstances are all soluble in acetic
acid, except the oxalate and the fluoride.  The precipitate
produced by the calcium reagent is, therefore, treated
with acetic acid; if it completely redissolves, oxalates and
fluorides are most probably absent. The presence of notable quantities of ammonium-salts renders this test of




~~ 48, 49           THE SILVER TEST.                  79
uncertain value; because the fluoride and many other
salts of calcium are soluble in solutions of amnmoniumsalts. Since sulphate of calcium is sparingly soluble in
water and acetic acid, the presence of a sulphate, causing
precipitation of sulphatue of calcium, obscures the reaction for oxalates and fluorides.  Nitrate of calcium must
be used instead of the chloride whenever silver or lead
salts, or mercurous salts, are present in the solution under
examination.
48. Illustration of the Calcium  Test.  Prepare in a
test-tube  an  aqueous solution  of phosphate, oxalate
and tartrate of sodium.  A very small quantity of each
salt will be enough. The solution will be neutral or
faintly alkaline. Add to this solution a solution of chloride of calcium  (~ 134) until the precipitation is complete.  Collect the white precipitate upon a filter, and,
when drained, transfer it to a test-tube and treat it with
acetic acid. The phosphate and tartrate of calcium will
redissolve, but the oxalate remains untouched. To verify
this result, and identify each one of the sodium salts present in the original solution, special tests, to be hereafter
described, must be resorted to.
49. The Silver Test. Nitrate of silver produces a precipitate in neutral or acid solutions with all chlorides,
bro-mides, iodides and cyanides, and in neutral solutions
with most of the classes of salts enumerated in ~ 45. In
order to obtain the most comprehensive negative conclusion in the case that nitrate of silver produces no precipitate, it is necessary to operate upon a neutral solution.
If the Qriginal solution be neutral, the nitrate of silver
may be immediately added to a portion of it. If no precipitate appear after the lapse of several minutes, neither




80.THE SILVER TEST.                ~ 49
chlorides, bromides, iodides, cyanides, sulphicldes, phosphates, arseniates, arsenites, chromates, silicates, oxalates,
nor tartrates can be present.  If the original solution
contained any considerable quantity of a borate, the
borate of silver would be precipitated under these conditions; but a small proportion of some borate might escape precipitation. If the original solution be acid to
test paper, add nitrate of silver to a portion of it in a testtube, and then pour in upon the liquid some dilute ammonia-water, so gently that the two liquids do not mix at
once. At some layer near the junction of the two dissimilar liquids, the fluid must be neutral. If at that layer
no precipitate or cloud appear, the twelve kinds of salts
above enumerated are absent. If the original solution is
alkaline, dilute nitric acid is to be added in precisely the
same manner as the ammonia-water in the opposite case.
The neutral layer between the two liquids is attentively
observed, and the absence of any film or cloud therein
justifies the same sweeping conclusion as that above given.. If any precipitate is produced by nitrate of silver, its
color is to be observed, for some conclusions may often
be drawn from this color. Chloride, bromide, cyanide,
oxalate, tartrate, silicate, and borate of silver are white;
iodide, phosphate, carbonate and arsenite of silver are
yellow; arseniate of silver is brownish-red; chromate of
silver is purplish-red; sulphide of silver is black. When
the silver precipitate is white, black, or of some obscure,
indecisive color, the operations in the wet way at this
stage should be directed to proving or disproving the
presence of chlorides, bromides, iodides, cyanides and
sulphides.  To this end the portion of the original solution which has been already tested with nitrate of silver,
should be made decidedly acid with dilute nitric acid. Of
all the silver salts which can be precipitated on the addi



~ 50                THE SILVER TEST.                  81
tion of nitrate of silver, only the chloride, bromide, iodide,
cyanide and sulphide can resist dilute nitric acid. If
the precipitate once formed redissolves completely in
nitric acid, no chloride, bromide, iodide, cyanide, or sulphide was present in the original solution. If, on the
contrary, a residue remain, one or more of these kinds of
salts must have been represented in the original solution.
If the residue be black or blackish, the presence of a sulphide is to be inferred; if it be white or'whitish, the absence of sulphides and the presence of a chloride, bromide, or cyanide is to be inferred; if it be distinctly yellowish, an iodide is probably present.  An experiment
will best illustrate the most appropriate treatment of a
silver precipitate insoluble in nitric acid.
50. Illustration of the Silver Test. Prepare in a testtube a weak solution of chloride of sodium, iodide of
potassium, cyanide of potassium, and phosphate of sodium. Add nitrate of silver (~ 131) to this slightly alkaline solution, until the precipitation is complete. The
dense precipitate is yellowish-white. Pour dilute nitric
acid into the mixture, until the solution is strongly acid;
shake up the contents of the tube thoroughly, and after
the lapse of several minutes collect the insoluble precipitate on a filter, and receive the filtered liquid in a testtube. If the filtrate be neutralized again with ammonia,
a yellow precipitate of phosphate of silver will reappear.
The precipitate on the filter is then thoroughly washed to
free it from the superfluous nitrate of silver. Wash the
precipitate into a clean test-tube, decant the water from
above it, pour over it ammonia-water, and gently heat the
mixture. The silver precipitate will visibly diminish in
bulk, but a yellowish portion remains undissolved. Filter
again, and neutralize the filtrate with nitric acid; a white




82          NITRATES, CHLORATES, ACETATES.         ~ 51
precipitate will fall. This experiment proves that a portion, but not all, of the mixed silver salts which are insoluble in nitric acid, are soluble in ammonia-water.  The
fact is that the chloride, cyanide and bronmide of silver dissolve in ammonia-water, the latter with difficulty, while
the iodide is insoluble in that reagent.
Special tests, hereafter to be described, are applied in
order to confirm the presence of iodine, and to detect
each and all of the three substances which are liable to
be confounded in the white precipitate just mentioned.
Cyanide of mercury does not give a precipitate with
nitrate of silver. When mercury has been detected in
the substance under examination, cyanogen  must be
sought for in other ways (~ 55) than this.
When the liquid under examination contains a ferrous
salt, protochloride of tin, or any other active reducing
agent, metallic silver is liable to be precipitated as a dark,
heavy powder. The examination for the metallic element
will generally have revealed the presence of any such
agent.
51. Nitrates, Chlorates, and Acetates. It is quite clear
that no method of precipitation whatever will apply to
nitrates, chlorates, and acetates, since these kinds of salts
are all soluble in water. No insoluble nitrate, chlorate,
or acetate is known. Special tests must be resorted to
for these three classes of salts.




~~ 52, 53          SPECIAL TESTS.                  83
CHAPTER X.
SPECIAL TESTS FOR THE NON-METALLIC ELEMENTS.
52., We now proceed to indicate the most available
special tests for the non-metallic elements and their commonest compounds.  It is noteworthy that the nonmetallic elements enter into composition under various
forms, which produce with one and the same metallic
element various salts. Thus within the narrow range of
this treatise, sulphur is to be sought in sulphides, sulphates, sulphites and hyposulphites; carbon in cyanides,
acetates, carbonates, oxalates and tartrates, and arsenic in
arsenites and arseniates. The various classes of salts will
be taken up successively. It should be premised that
these special tests are sometimes applied to the original
solution, before the precipitation with chloride of barium
and nitrate of silver, and sometimes during or after these
more general testings. In the first case the student is
seeking guidance in the application of the more comprehensive tests; in the latter case he is trying to confirm
results already almost sure.
53. Effervescence. WThen a solution containing a carbonate, cyanide, sulphide, sulphite, or hyposulphite, or a
mixture of representatives of some or all of these kinds
of salts, is treated with chlorhydric acid and then warmed,
an evolution of gas occurs with more or less effervescence.
The gases evolved are all colorless; but they all have very
characteristic odors except carbonic acid, the gas which




84                   CARBONATES.                  ~ 51
escapes from  a carbonate.  A cyanide gives off the
pungent odor of cyanhydric acid. A sulphide yields sulphuretted hydrogen of familiar presence. Sulphurous
acid escapes from sulphites and hyposulphites alike; but
in the latter case a deposition of sulphur makes the liquid
turbid. If only one of these gases were present, the effervescence and the smell would identify it; but when mixtures are to be dealt with, further means of identification
are necessary.
54.  Carbonates. To prove the presence of carbonic
acid gas, when effervescence has occurred, add chlorhydric acid, little by little, to the effervescing solution,
until the acid is decidedly in excess; meanwhile keep the
mouth of the test-tube loosely closed with the thumb to
promote the accumulation of the gas evolved. When the
tube is supposed to be full, carefully decant the gas into
a second test-tube containing a teaspoonful of lime-water
(~ 133), taking care not to allow any of the liquid to pass
over with the gas. Mix the lime-water and the gas in the
second test-tube by thorough shaking. A white precipitate
of carbonate of calcium will be produced, if the gas tested
is, or contains, carbonic acid.
If the effervescence is slight, and the quantity of gas
evolved seems too small to be decanted in this way, dip the
end of a dark-colored glass rod into lime-water, and
thrust the moistened end into the test-tube, bringing it
close to the surface of the fluid. If the gas be carbonic
acid, the lime-water adhering to the rod will become
visibly turbid.
The student who desires to see the working of this test
before having occasion to apply it in an actual analysis,
can operate upon a morsel of carbonate of sodium dissolved in a little water.




~ ~ 55, 56       CYANIDES-SULPHIDES.                85
55.  Cyanides. When the smell of the gas which
escapes from the solution under examination (~ 53), or
the qualities of the precipitate with nitrate of silver
(~~ 49, 50), give occasion to suspect the presence of a
cyanide, the following confirmatory test may be resorted
to:-Add to the solution supposed to contain free cyanhydric acid, or an alkaline cyanide, a few drops of a solution containing both a ferrous and a ferric salt (a solution
of ferrous sulphate which has been exposed to the air, for
example), and a small quantity of caustic sodalt solution.
If cyanogen is present, a bluish green precipitate forms,
which consists of a mixture of Prussian-blue and the
hydrates of iron. Warm the liquid, and add to it an
excess of chlorhydric acid. The hydrates of iron dissolve,
but the Prussian-blue remains undissolved.
If only a very small quantity of cyanogen be present,
the liquid  simply appears green  after the  addition
of chlorhydric acid, and it is only after long standing
that a trifling blue precipitate separates from it.
This test may be well illustrated by means of a small
particle of cyanide of potassium dissolved in a teaspoonful of water.
To detect cyanogen in cyanide of mercury, it is necessary to precipitate the mercury as sulphide, by means of
sulphuretted hydrogen, and to identify the free cyanhydric acid in the filtered or decanted fluid.
56. Sulphides. Many sulphides give off sulphuretted
hydrogen when heated with chlorhydric acid.  If the
quantity of gas is so small that its odor is imperceptible,
the lead-paper test (~ 31) should be applied.
When sulphides are dissolved in nitric acid or aquaregia, their sulphur is partly separated in a free state and
partly converted into sulphuric acid. The free sulphur is
5




86             SUJLPHITES-HYPOSULPHITES.       ~~ 57-59
identified by its color and texture, and by its behavior
when burnt. The sulphuric acid in the liquid is detected
in the usual manner (~ ~ 45, 46).
57. Sulphites. All the sulphites evolve sulphurous acid,
without any deposition of sulphur, when treated with
chlorhydric acid. The very sharp odor of this gas is
enough to identify it.
As has been before stated, nitrate of silver produces in
solutions of sulphites a white precipitate; but this precipitate blackens when the liquid is boiled, on account of
the reduction of silver.
When the sulphites are heated with strong nitric acid,
or other powerful oxidizing agent, they are converted into
sulphates without precipitation of sulphur.  The sulphates so produced may be identified in the usual way
(~~ 45, 46).
58. BZ/yposulphiles. The hyposulphites disengage sulphurouns acid and deposit sulphur when warmed with
chlorhydric acid. This decomposition is not immediate
if the solution be dilute.
The precipitate produced in the solution of a hyposulphite by nitrate of silver, dissolves again readily in an
excess of the hyposulphite.  On standing, the precipitate
of hyposulphite of silver turns black spontaneously, being
decomposed into sulphide of silver and sulphuric acid.
Heating produces this effect almost immediately.
Hyposulphite of socium is a good salt from which to
get the above reactions of hyposulphites.
59. During the examination for the metallic elements,
chromium and arsenic are detected, and the analyst generally obtai_.s pretty certain evidence concerning the




~~ 60, 61 CHROMATES-ARSENITES AND ARSENIATES.        87
actual condition in which these elements enter into the
substance under examination, whether as chromate or
salt of chromium, as arsenite or arseniate; for a chromate is reduced with change of color (~ 22), and sulphide
of arsenic is thrown down immediately from an arsenite,
but only after long contact with sulphuretted hydrogen
from an arseniate. To confirm the indications then obtained, the following tests are used.
60.  Chromates. WVhen acetate of lead (~ 137) is added
to a neutral solution of a chromate, yellow chromate of
lead separates, insoluble in acetic acid, but soluble in
caustic soda.
As has been before stated, the purplish-red color of
chromate of silver (~ 49), and the yellow color of chromate of barium  (~ 46), are valuable indications of the
presence of a chromate.
A solution of normal chromate of potassium is the best
substance from which to obtain for the first time the reactions of chromates.
61. Arsenites and Arseniates. Though sure of the presence of arsenic, the analyst is often left in doubt which
of these two classes of arsenic compounds he has to deal
with. Discriminating tests are necessary.
A neutral solution of an arsenite yields with nitrate of
silver a yellow precipitate of arsenite of silver. A neutral
solution of an arseniate gives with the same reagent a
brownish-red precipitate of arseniate of silver. Both
these precipitates are readily soluble in dilute nitric acid
and in ammonia, and they are by no means insoluble in
nitrate of ammonium.  If solutions containing free arsenious or arsenic acid are to be tested, they must first be
cautiously neutralized with the least possible quantity of
a:izmonia-water.




88              SULPHATES-PHOSPHATES.          ~~ 62, 63
The above tests are generally sufficient, but circumstances may arise in which they would be inapplicable.
The following tests afford further means of discrimination:If to a solution of arsenious acid or an arsenite, caustic
soda be first added in excess, and then five or six drops
of a dilute solution of sulphate of copper, a clear bluish
liquid is obtained, which, upon boiling, deposits a red
precipitate of dinoxide of copper (Cu20), while soluble
arseniate of sodium is simultaneously produced, and remains in the solution. This test is good as a means of
distinguishing between arsenites and arseniates when no
organic matters are contained in the solution under examination.  The qualification is necessary, because grapesugar and many other organic substances exercise a like
reducing action on copper salts.
If a solution of arsenic acid, or of an arseniate soluble
in water, be added to a clear mixture of sulphate of magnesium, chloride  of ammonium  and  anymmonia-water
(~ 139), a crystalline precipitate of arseniate of magnesium
and almmonium will separate, after an interval which is
short in proportion to the concentration of the arsenic
solution.
62. Sulphates. The chloride of barium  test (~~ 45,
46) is all-sufficient for the detection of sulphates.  The
operator should make sure that the chlorhydric acid
itself contains no sulphuric acid, that an excess of acid is
really present, and that the solution is tolerably dilute.
Concentrated acids and strong solutions of many salts
impair the delicacy of the reaction.
63. Phosphates.  When  the previous steps of the
analysis have proved that the phosphates present in the




~ 63                  PHOSPHATES.                   89
solution under examination are soluble in ammoniacal
liquids, and that no arsenic acid or arseniates are present,
the following test will satisfactorily identify a phosphate
or free phosphoric acid:Add to the solution to be tested a clear mixture of sulphate of magnesium, chloride of ammonium  and aminonia-water (~ 139). When a phosphate or free phosphoric
acid is present, a white, crystalline precipitate of phosphate of magnesium  and ammonium  is formed, even in
very dilute solutions.  Stirring and shaking promote its
separation.  The precipitate dissolves readily in acids.
When arsenic acid or arseniates are present in the
original mixture, this test for phosphates can still be applied, if all the arsenic be previously removed by precipitation as sulphide (~ 23). The magnesium  mixture can
be used in the filtrate from the sulphide of arsenic.
The preceding test can only be applied when the phosphate present is soluble in ammoniacal solutions. The following test is of much more general application; it can be
used in presence of arsenic acid, and is applicable to
either neutral or acid solutions of phosphates; it is also
extremely delicate.
WVhen two or three dclropsof a neutral or acid solution
of a phosphate (even of iron, aluminum, barium, strontium, calcium or magnesium [compare ~ 27]), are poured
into a test-tube containing four or five teaspoonfuls of a
solution of molybdate of ammonium in nitric acid (~ 115),
there is formed in the cold a pale-yellow precipitate which
is apt to gather upon the sides and bottom  of the tube.
If the precipitate does not appear in a few minutes, a few
drops more of the solution to be tested may be added.
This precipitate is soluble in an excess of phosphoric and
other acids; and certain organic substances also prevent
its formation. A yellow coloration of the liquid merely




90               OXALATES-TARITRATES.          ~~ 64, 65
is not enough to prove beyond question the presence of a
phosphate; a precipitate must be waited for. The yellow
precipitate can be easily recognized, even in dark-colored
liquids, when it has settled.  The solution to be tested
must not be heated, nor must it be more than bloodwarm.
Phosphate of sodium is the best substance on which to
try the test for phosphates.
64. Oxalates. The precipitation of white, finely divided oxalate of calcium, by all soluble calcium  salts, from
solutions of oxalates or oxalic acid, has been already described (~ 48). Even the solution of sulphate of calcium
gives this reaction with oxalates.
If oxalic acid, or an oxalate in the dry state, be heated
in a test-tube with an excess of concentrated sulphuric
acid, a mixture of carbonic oxide and carbonic acid is set
free with effervescence; the carbonic acid may be identified by the lime-water test; and if the quantity operated
upon is considerable, the carbonic oxide may be inflamed
at the mouth of the tube.
65.  Tartrates. Tartaric acid and the tartrates, when
heated in the dry state char, and emit a very characteristic odor which somewhat resembles that of burnt sugar.
This is the only class of salts, among all those within the
scope of this treatise, which exhibit this carbonization
by heat. Strong sulphuric acid blackens tartaric acid
and the tartrates.
To confirm  the presence of tartaric acid, or a tartrate,
in any liquid supposed to contain it, a concentrated solution of acetate of potassium  is added to the liquid, and
the mixture violently shaken. The precipitate, when one
forms, is a difficultly soluble acid tartrate of potassium.




~ 66                   BORATEIS.                    91
The addition of an equal volume of alcohol increases
the delicacy of the reaction.  The more concentrated
the solution to be tested, the better. To prepare the
required solution of acetate of potassium at the moment
of use, rub together in a dish half a teaspoonful of carbonate of potassium  and as many drops of acetic acid
as will dissolve three-quarters of the carbonate; throw
the mixture on a small moistened filter and use the
filtrate.
Tartaric acid is a good substance from which to get
these reactions.
66. Borates. To confirm the presence of a borate,
strong sulphuric acid is mixed with the dry substance
under examination in quantity sufficient to make a thin
paste, and an equal bulk of alcohol is added to the
mixture.  The alcohol is then kindled.  Boracic acid
imparts to the alcohol flame a yellowish-green color.
The test is made more delicate by stirring the mixture,
and by repeatedly extinguishing and rekindling the
flame. Copper salts impart a somewhat similar color to
the flame; but this metal, if present, may be got rid of
by sulphuretted hydrogen before testing for boracic
acid.
If a solution of boracic acid, or of a colorless borate,
is mixed with chlorhydric acid to slight but distinct acid
reaction, and a slip of turmeric paper (~ 149) is dipped
half way into the liquid and then dried at 100  C., the
dipped half shows a peculiar red tint.  This test is delicate, but there are a few other solutions which impart,
not the same, but somewhat similar tints to turmeric
paper.
The reactions of borates may be obtained with a fragment of borax.




92                SILICATES-FLUORIDES.          ~~ 67, 68
67.  Silicates.  The silicates of sodium and potassium
are the only silicates which are soluble in water. The
solutions of these alkaline silicates are decomposed by all
acids.  If chlorhydric acid is added gTadually to a strong
solution of an alkaline silicate, the greater part of the
silicic acid separates as a gelatinouts hydrate.  As a rule,
the amore dilute the fluid, the more silicie acid remains in
solution.
If the solution of an  alkaline silictate, mixed  with
ehlorhydric or nitric acid in excess, be evaporated to
dryness, silicie acid separates; if the dry mass be ignited
and then treated vwith dilute chlorhydric or nitric acid,
the whole of the silicic acid remains insoluble in the free
state, as a gritty, whitish powder,, while the other substances dissolvee.
A solution of chloride of aimconiumr produces a gelatinous precipitate in strong and moderately dilute solutions of the alkaline silicates.  This precipitat.e is hydratecl silicie acid containing alkali.
A solution of waterglass is the best substance in which
to stucdy the reactions of the silicates of the alkali-metals.
63.  Flutorides.  If a finely pulverized fluoride is heated in a small leaden capsule or platinum crucible with
concentrated sulphuric acid, fluorhydric  acid is disengaged.
Coat with wax the convex face of a watch-glass large
enough to cover the capsule, by heating the glass cautiously, and spreading a small bit of wax evenly over it
while the glass is hot.  Trace some lines or letters
throu ogh the wax with a pointed instrument of wood or
horn. Fill the hollow of the glass with cold water, and
cover with it the capsule which contains the fluoride mixture.  Heat the capsule gently for half an hour or an




~ 69                  CHLORIDES.                    93
hour. Then remove the watch-glass, dry it, heat it cautiously to melt the wax, and wipe it with a bit of paper.
The lines or letters traced throug'h the wax will be found
etched into the glass. A barely perceptible etching is
made more visible by breathing upon the glass. If much
silicic acid is present, this reaction fails.
When a fluoride, naturally combined or artificially
mixed with  silica, is heated  with  strong sulphuric
acid, fluoride of silicon is evolved.  This reaction is
available as a test for fluorine.
A mixture of the supposed fluoride and fine dry sand
is heated in a short, dry test-tube, with concentrated sulphuric acid. A drop of water, caught in the loop of a
clean platinum wire, is held in the mouth of the test-tube.
This drop of water becomes merely dim, quite opaque, or
almost solid with silicic acid, according to the quantity of
fluoride of silicon evolved from the mixture. The gaseous
fluoride of silicon shows white fumes when it comes in
contact with moist air. If a considerable quantity of
fluoride of silicon be evolved from  the mixture tested, it
can be decanted into another test-tube, and there shaken
up with water. If the substance to be tested for fluorine
is known to contain silica, it is, of course, unnecessary to
add sand to it. This method applies to all fluorides decomposable by hot sulphuric acid. It is evident that this
test reversed can be applied to the detection of silica.
Fluoride of calcium (fluor-spar) is a good material
from which to obtain these two tests for fluorine.
69.  Chlorides. The following confirmatory test is applied to chlorides in the dry state:WThen a chloride, in powder, is heated in a test-tube
with black oxide of manganese and strong sulphuric
acid, chlorine gas is evolved; this gas is recognized by
5*




94                   BROMIDES.                  ~ 70
its odor, greenish-yellow color, and reaction with iodostarch paper. The gas evolved by a chloride gives no
colored reaction with starch alone; but when a moistened
slip of paper, on which a mixture of starch paste and
iodide of potassium (~ 130) has been spread, is held in
an atmosphere or current of chlorine, the paper is colored
blue in consequence of the liberation of iodine which the
chlorine effects. The yellow color of the gas is best seen
by looking lengthwise through the tube.
70. Bromides. The confirmatory tests for bromides
depend upon the setting free of bromine itself.
Hot nitric acid liberates the bromine from all bromides
except those of silver and mercury. In solutions, the
free bromine produces a yellow coloration; when set free
from solid bromides, the brownish-yellow vapors of broimine condense into a liquid upon the cold walls of the
tube.
WVhen bromides, in powder, are heated in a test-tube
with black oxide of manganese and strong sulphuric acid,
brownish-red vapors of bromine are evolved. If chlorides are also present, the bromine will be mixed with
chlorine.
To identify bromine and distinguish it from chlorine,
moistened starch is brought into contact with the free
bromine. A yellow or orange-yellow coloration of the
starch marks the presence of bromine. To apply this
test, thrust a rod smeared with starch-paste into the tube
which contains the bromine vapors; or, when greater
delicacy is requisite, perform the experiment which is
expected to liberate bromine in a very small beaker, and
cover this beaker with a watch-glass to whose under-side
is attached a bit of paper moistened with starch-paste
and sprinkled with dry starch.




~~ 71, 72         IODIDES-NITRATES.               95.
Bromide of potassium is a good substance with which
to study the tests for bromine.
71. Iodides. When an iodide, in the solid form or in
solution, is heated with strong nitric acid, iodine is liberated and sublimes in violet vapors.
Free iodine in vapor is recognized by the deep blue
color which it imparts to starch-paste. Vapors may be
tested by bringing into contact with them a glass rod
smeared with thin starch-paste, or a slip-of white paper
on which the paste has been spread.
The best method of detecting iodine in a solution is
to add a few drops of thin, clear starch-paste to the
liquid, and then set free the iodine by means of nitrite
of potassium (~ 129), as follows:-The cold fluid to be
tested is acidulated with dilute chlorhydric or sulphuric
acid, after the addition of the starch-paste, and a drop or
two of a concentrated solution of nitrite of potassium is
then added. A dark blue color will be instantly produced. It is essential that the liquid should be kept cool,
for the blue coloration is destroyed by heat.
Like chlorine and bromine, iodine is liberated by heating an iodide with black oxide of manganese and sulphuric acid. The iodine so liberated is readily distinguished
by the above tests.
The student can try all these tests for iodine with a
small crystal of iodide of potassium.
72. Nitrates.  To confirm the presence of a nitrate,
one or both of the two following tests may be used:If the solution of a nitrate is mixed with an equal
volume of strong sulphuric acid, the mixture cooled in
cold water, and a concentrated solution of ferrous sulphate then cautiously added to it in such a way that the




96                    CHLORATES.                   ~ 73
two fluids do not mix, the stratum  of contact shows a
purple or reddish color, which changes to a brown. If
the fluids are then mixed, a clear, brownish-purple liquid
is obtained.  The color fades on heating. Another way
of performing the same test is to drop a crystal of copperas into the cold mixture of nitrate and sulphuric acid.
There forms around the crystal a dark halo, which disappears with a kind of effervescence on the application
of heat. It is, of course, essential that the sulphuric
acid employed for this test should be so free from nitric
and hyponitric acids, as not itself to give this reaction
with ferrous sulphate.
Boil some chlorhydric acid in a test-tube, add to it one
or two drops of a dilute solution of sulphindigotic acid
(~ 147), and continue the boiling a moment. If the
chlorhydric acid is sufficiently free from chlorine, the resulting liquor will be of a faint blue color. If a nitrate,
either solid or in solution, be added to this liquid, and
the mixture be again boiled, the liquid will be decolorized. This reaction is delicate; but there are some other
substances, especially free chlorine, which have a like
bleaching effect.
Nitrate of potassium is a suitable material on which to
illustrate the tests for nitrates.
73.  Chlorates.  The preliminary examination gives
warning of the presence of chlorates.
When a few particles of a chlorate in the solid form
are covered with two or three times as much strong sulphuric acid, and the mixture is gently warmed, the liquid
becomes intensely yellow, and a greenish-yellow irritating
gas of peculiar odor (hypochloric acid, C102) is evolved,
which explodes with violence at a moderate heat. After
this decomposition, the gas evolved has the characteristic




~ 74                   ACETATES.                    97
odor of chlorine.  The quantity of chlorate operated
upon should be very small.
The solution of a chlorate decolorizes indigo-solution
precisely like the solution of a nitrate, under like conditions (~ 72).
A chlorate is converted by ignition into chloride, from
a solution of which nitrate of silver precipitates the
chlorine.
Chlorate of potassium  illustrates very well the reactions of chlorates.
74. Acetates. When acetates are moderately heated
with strong sulphuric acid, hydrated acetic acid distils
from the mixture, and may be recognized by its pungent
odor.
When an acetate is heated with alcohol and sulphuric
acid in equal volumes, acetic ether is formed. The agreeable odor of -this ether is highly characteristic.
Hot concentrated sulphuric acid produces no blackening with an acetate.
When a few drops of a solution of ferric chloride
(~ 140) are added to a solution of a neutral acetate, or to
a solution of an acetate previously neutralized  with
ammonia, the liquid acquires a dark red color, because of
the formation of ferric acetate. If the liquid contain an
excess of the acetate, a basic acetate of iron is precipitated in yellow flocks upon boiling, and the fluid finally
becomes colorless.








PARiT SECOND.
PRELIMINARY TREATMENT.
THE ORDER OF PROCEDURE.
75. The substance to be examined may be either solid
or liquid. We shall consider first the preliminary treatment of a solid; afterwards that of a liquid. The solid
may be a metallic substance, that is, a pure metal or an
alloy, or it may be a salt, mineral, or other non-metallic
body. The method of procedure differs in the two cases.
WTe shall describe first the treatment of a salt, mineral,
or other non-metallic substance. The two following
observations, however, apply to all cases. The student
should, in the first place, learn as much as possible from
the external properties of the substance to be analyzed,
from its color, consistency, and odor, if it is a liquid;
from its color, texture, odor, lustre, hardness, gravity, and
crystalline or amorphous structure, if it is a solid. By
attentively observing the characteristics or individual
peculiarities of every substance which passes through his
hands, the student will soon learn to recognize many substances at sight,-by far the quickest and easiest way of
identifying them. Secondly, since the original substance
must be several times reverted to in order to complete O.n




100               CLOSED-TUBE TEST.             ~ 76
analysis, the student should husband his stock of the
substance to be analyzed, never employing the whole of
it for any single course of experiment. It is well also to
reserve a portion for unforeseen contingencies.
CHAPTER XI.
TREATMENT OF A SALT, MINERAL, OR OTHER NONMETALLIC SOLID.
A. PRELIMINARY EXAMINATION IN THE DRY WAY.'76. Closed-tube Test. Prepare a hard glass tube No. 4
(~ 171), about 3 inches long, and closed at one endcl. Let
fall into this tube a minute fragment of the solid, or a
little of its powder. If the substance be used in powder,
wipe out the tube with a tuft of cotton on a wire, in order
that the interior walls of the tube may be clean to receive
a sublimate. Heat the substance at the end of the tube,
at first gently in the lamp, but finally intensely in tile
blow-pipe flame. The following are the most noteworthy
reactions with the inferences to be drawn from them; it
not unfrequently happens that a single substance gives
several of these reactions:I.  The substance blackens, and gases or vapors are
evolved. These vapors often have a disagreeable smell,
sometimes like that of burnt sugar, paper, or feathers.
Sometimes they condense in tarry droplets; water also
condenses on the cold part of the tube. These appearalnces indicate the presence of organic substances.
Now, the presence of fixed organic matter interferes




~ 76               CLOSED-TUBE TEST.               101
with the detection of many substances, and it must be
destroyed before the analysis can be proceeded with. A
portion of the original substance, sufficient for the regular
course of examination for the metallic elements, is ignited
in a porcelain crucible, with free access of air, or on platinum foil, if the presence of no metal be suspected, until
all the carbon is burnt out of it. This ignition is best
performed on successive small portions rather than on a
large mass at once.
It is obvious that some inorganic volatile matters may
be lost during this ignition.  Furthermore, some substances, especially alumina and chromic and ferric oxides,
are made very insoluble by ignition.  Exceptionally,
therefore, the following process, which is not liable to
these objections, is employed:-The substance in powder,
paste, or concentrated solution, is heated in an evaporating-dish, with strong nitric acid, to a temperature just
below boiling. To this hot mixture chlorate of potassium,
in small bits, is added gradually, until the organic matter
is all destroyed. The solution is then evaporated to dryness on a water-bath; the dry residue is moistened with
strong chlorhydric acid, the mixture diluted with water,
warmed and filtered, if there be any residue. The filtrate
is fit for the regular course of analysis, except that potassium, having been added, must not be tested for in this
liquid. The residue, if any, must be examined for the
insoluble chlorides of Class I. This process is simply a
combustion at a low temperature.
Simple blackening is not proof of the presence of organic bodies.  Some salts of copper and cobalt, for example, blacken through the formation of a black oxide.
WVhen organic matter is shown to be present, the
student should look particularly for acetic (~ 74)'and tartaric (~ 65) acids; but he will not forget that there are




102               CLOSED-TUBE TEST.              ~ 76
hundreds of organic acids which are not comprehended
in the plan of this treatise.
II. The substance does not carbonize, but vapors or
gases escape from it. The most important are:a. Aqueous vapor, which condenses in the upper part
of the tube. Test this water with litmus paper; if it is
alkaline, ammonia may be suspected; if acid, some volatile acid (H2SO4, IC1I, HBr, HI, H-IF1, HN3, &c).
b. Oxygen, recognized by its relighting a glowing
match. This gas indicates nitrates, chlorates, and peroxides. If the heated substance fuses, and a small fragment of charcoal thrown in is energetically consumed,
the presence of a nitrate or chlorate may be assumed.
c. Hyponitric acid, recognized by the brownish-red
color of the fumes. It results from the decomposition of
nitrates.
d. Sulphurous acid, recognized by its odor. It not unfrequently results from the decomposition of sulphates,
sulphites, and sulphides.
e. Carbonic acid, derived from decomposable carbonates, and to be recognized by lime-water (~ 54).
f.  Cyanogen, derived from  decomposable cyanides,
and to be recognized by its odor, and the blue flame with
which it burns when there is enough of it to be lighted.
g. Sulphydric acid gas, derived from moist sulphides
and to be known by its smell.
h. Ammonia, resulting sometimes from the decomposition of ammoniacal salts.




~ 76              CLOSED-TUBE TEST.               103
III. A sublimate forms beyond the heated portion of
the tube. The whole of the substance may volatilize.
The following are the commnonest sublimates:a. Sulphur, which sublimes in reddish drops. The
sublimate becomes solid and yellow, or yellowish-brown,
on cooling.
b. Ammonium-salts give white sublimates.  Test a
separate small portion of the original substance for the
salts of ammoniTum, by mixing it in a small test-tube with
an equal bulk of slaked lime and a few drops of water,
and heating the mixture. Ammonia, when evolved, may
be recognized by its smell, and by the white fume produced when a rod, moistened with a mixture of equal
parts of strong chlorhydric acid and water, is held above
the mouth of the tube. Unless the original solid is obvionsly inalterable by heat, it should be invariably tested
in this way for ammonium-salts.
c. Metallic mercury and some of its compounds. The
metal sublimes in metallic droplets. The two chlorides
of mercury give sublimates which are white when cold.
The red iodide of mercury gives a yellow sublimate. The
sulphide of mercury gives a dull black sublimate.
d. Arsenic and some of its compoudnls. Metallic arsenic
gives a black sublimate of metallic lustre. Arsenious
acid gives a white sublimate, which looks crystalline
under a magnifying lens. The sulphides of arsenic give
sublimates which are brownish-red while hot, but reddishyellow to red when cold. These sublimnates look not unlike that of pure sulphur.
e. Teroxide of antimony first fuses to a yellow liquid,
and lthen gives a white sublimate, composed of needlelike crystals.




104                REDUCTION TEST.               ~ 77
f. Oxalic acid gives a white, crystalline sublimate,
with dense fumes in the tube.
The inferences to be drawn from this simple preliminary
experiment are of very unequal value. Thus the detection of organic matter is of the first importance, because,
as has been seen, such matters must be got rid of before
the analysis can be proceeded with. Again, nitrates and
chlorates should be detected with a good degree of certainty by their reactions in the closed tube. Thirdly, the
presence, or entire absence, of ammonium-salts should be
put beyond doubt at this first stage of the examination.
Fourthly, the presence of mercury, or of mercurous salts,
determines the choice of the acid solvent in favor of
nitric acid, in case water will not dissolve the substance
under examination (~ 81), and the presence of mercuric
salts renders necessary the substitution of sulphydrate of
ammonium for sulphydrate of sodium as the solvent for
the sulphides of Class III (~ 43). Accordingly, it is useful
to get information of the presence of mercury or its compounds at this early stage of the examination. As to the
other appearances, they give information which may be
convenient, but is never essential for the safe conduct of
the regular course of analysis. They have been described
because they may occur with or instead of the really important reactions.'77. Reduction Test. Mix a little of the powder of the
substance under examination (the bulk of a hemp-seed)
with an equal quantity of carbonate of sodium, and
make the mixture into a pasty ball with a small drop of
water.  Select a piece of dry, well-burned, soft-wood
charcoal, and cut out of it a rectangular block about 6
inches long, 1~ in. wide, and I to 4 in. thick, having its




~ 77             METALLIC GLOBULES.             105
fiat, smooth surface (6 in. by 1 in.) at right angles to the
rings of growth in the tree. It is this surface which is
always to be used. A good piece of charcoal may be
made to serve for many assays, by filing off the used surface and exposing a new one. At a quarter to half an
inch from the end of such a piece of charcoal, scoop out
with a penknife a little cavity of the size of half a pea.
Place the prepared pellet in this cavity, and expose it for
several consezcutive minutes to the reducing flame of the
blow-pipe (~ 167).
Under these conditions, vapors of characteristic odor
or appearance may be evolved; some of them  will be
mentioned below. The two objects, however, to which
attention is specially to be directed are the residue in the
cavity and the incrustation on the charcoal outside of the
cavity.
The following metals may be found as fused metallic
globules in the cavity; lead, silver, and gold are reduced
with ease, even by an inexperienced operator; tin and
copper with some difficulty:a. Gold -a yellow, malleable globule, produced without incrustation.
b. Copper-a red, malleable globule, produced without
incrustation.
c. Tin-a bright, white, malleable globule. An incrustation is simultaneously produced, which
is faint yellow when hot, and white when
cold; it immediately surrounds the globule.
d. Lead-a very fusible and very malleable globule.
A yellow incrustation is simultaneously produced.
e. Silver-a brilliant, white, malleable globule, produced without incrustation.




106              METALLIC GLOBULES.             ~ 77
Two other common metals, bismuth and antimony,
may be reduced to gray metallic globules; but these
globules are brittle, and are not liable to be confounded
with the malleable globules just described.  Bismuth
gives a yellow incrustation which resembles that of lead.
Coiammon charcoal is itself very apt to show a grayish
incrustation of ash round about the heated assay; this
incrustation remains unaltered or increases, when directly
exposed to the flame. The student should test each piece
of charcoal before the blow-pipe flame, in order that he
may not imagine a deposit of ash to be an incrustation
derived from the substance under examination.
If a distinct globule has been obtained, it must be
picked out with a pair of jewellers' tweezers, and pounded
on some smooth and hard body to test its malleability.
If it is malleable, replace it upon the charcoal at an unused spot, and heat it strongly with the oxidizing flame.
Gold and silver globules fuse, but maintain their brilliancy
and give no incrustation; this proof distinguishes a
genuine gold globule from a yellow globule composed of
an alloy of copper and some white metal. A yellow
globule composed of oxidizable metals tarnishes instantly
in the oxidizing flame. A tin globule fuses, but its bright
surface is instantly tarnished, and a white incrustation of
binoxide of tin is produced which cannot be driven off by
either flame. A lead globule is rapidly converted into
litharge, a yellow incrustation being produced, which
volatilizes with a bluish color when touched with the
reducing flame. A copper globule is blackened by the
formation of oxide of copper, and the blow-pipe flame is
tinged with green.
Certain other phenomena may manifest themselves
during the experiment for the reduction of malleable
metallic globules. Sulphur, ammonium-salts in general,




~ 77              METALLIC GLOBULES.              107
the chlorides, bromides, iodides, and sulphides of sodium
and potassium, the chlorides of lead, bismuth, tin and
copper, metallic mercury, arsenic, antimony and zinc, and
many compounds of these four elements, are liable to pass
off in vapors, which are often in part deposited upon the
coal at a greater or less distance from  the hot assay
according to their volatility. With the exception of sulphur, these sublimates are white, but when deposited in
a thin film upon the black coal they have a gray or blue
appearance.  During the production  of the arsenic
sublimate a peculiar odor is evolved; this sublimate
being very volatile is only deposited at a considerable
distance from the assay. The incrustation produced by
zinc is distinctly yellow while hot, but turns white on
cooling; it settles near the assay and is driven away again
with difficulty.
These phenomena are all of secondary importance; the
main object of the experiment is the reduction of the five
malleable metals above enumerated. We may thus obtain
knowledge of the presence of gold (for a confirmatory
test, see ~ 92, b), a metal not included in our scheme of
analysis in the wet way. Tin generally gives warning of
its presence during this experiment; and this warning is
of use, because it is inconvenient to apply nitric acid as a
solvent to a substance containing tin, since this reagent
converts tin into the very insoluble binoxide of tin.
The detection of copper at this stage is of little advantage.  The most important fact deducible from
the reduction-test is the presence of either silver or
lead.
In dissolving an unknown substance which proves to
be insoluble in water, it is customary to try, as the second
solvent, chlorhydric  acid.   The chlorides of silver
and  lead  being insoluble, or difficultly soluble, this




108               DISSOLvING IN WATER.          ~~ 78, 79
acid should not be used as a solvent when either
of these two metals is present. Nitric acid must be used
instead.
B. DISSOLVING A SALT, MINERAL, OR OTHER NON-METALLIC
SOLID, FREE FROM ORGANIC MATTER.
78, iBefore a solid substance can be submitted to the
systematic course of analysis, it must be brought into solution.  There is no universal solvent.  Different substances require different solvents.  The four solvents
employed in qualitative analysis for salts, minerals, and
other non-metallic solids, are water, chlorhydric acid,
nitric acid, and aqua-regia; and these four liquids are
invariably to be tried in the precise order in which they
here stand. Water is always to be tried first; to whatever resists water, strong chlorhydric acid is applied; if
chlorhydric acid fails to dissolve the solid completely, or
is unsuitable, for reasons disclosed in the preliminary
examination as just explained, nitric acid is tried, and
after nitric acid, aqua-regia as the last resort.  A solid
substance should invariably be reduced to a very fine
powder, before being submitted to the action of solvents
(~ 180).
79. Dissolving in wvater. About half a thimbleful of
the powdered substance is boiled with ten times as much
water in a test-tube.  If an effervescence occurs, as is
possible with mixtures containing an acid salt (yeastpowders, for example), the gas evolved should be carefully
tested (~~ 53-58). If the substance dissolves completely,
the solution is ready for analysis.  When undissolved
powder remains in the tube after protracted boiling, filter
a few drops of the liquid, and evaporate a drop or two of




~ 80              AN AQUEOUS SOLUTION.                 109
the filtrate to dryness on clean platinum foil, at as low a
heat as possible.  If there be no residue on the foil, or if
t.he residue be scarcely appreciable, the substance is practically insoluble in water, and acids must be tried as
solvents.  But if, on the contrary, a tolerable residue remains on the foil, decant the liquid in the tube into the
filter, and boil the powder again with water.  Persevere
with this treatmnent until it is evident that a part of the
powder is insoluble in water.  The insoluble residue in
the test-tube is thrown upon the filter; the clear liquids
which have passed through the filter, collected together
and concentrated by evaporation if of unreasonable bulk,
are ready for the regular course of analysis.  In this
case, and in the still more favorable case in which all the
substance has dissolved in water, it is a simple aqueous
solution which is subimitted to analysis.
80.  An aqueous solution.  If the student is assired
thllat the unknown substance is a simple salt, he may draw
some trustworthy inferences from  the fact that the substance dissolves in water.  Of the salts which fall within
the scope of this manual, the following are practically
soluble in water:
1.  A11 salts of sodium, and all of potassium  and ammonium.  except their double platinum-chlorides.
2   All nitrates, chlorates,:and acetates.
3. Chlorides, bromides, and iodidles, except those of;silver  and nmercury.  (ercuric  chloride is
soluble, The lead sals are difficultly soluble.)
4.  Sulphates, except those of barium,,strontium, and
leadc
a_




110           TESTING AN A(QUEOJS SOLUTION             ~ 80
5. IMany hyposulphites.
6.  The sulphi.de  of sodium, potassium, allllonium,
mnagnesium, barium, strontilum, and calcium.
7.  A few cyanides, oxalates, tartrates, and chromates,
besides those of the alkali-metals already mentioned.
It is obvious that any element of the thirty-six considered in this treatise, may be present in an aqueous
solution; but it is also evident from the above list, that a
great number of salts are absolutely excluded because of
their inso!ubility in water.
If, on the contrlary, there is no certainty that the substance under examination is not a complex artificial mixture, no safe conclusions can be drawn from  the fact that
a part of it, or the whole of it, dissolves in water.
Test the solution with litlmus paper.  The solution is
either neutral, acid, or alkaline.
Neutral.  The normal salts of most of the metals have
an acid reaction.  Sodium, potassium, barium, strontium,
calcilum, magnesium, manganese, and silver are the only
metallic elements which form  salts whose solutions are
neutral. Add to two or three drops of the solution a drop
or two of carbonate of sodium.  If a precipitate forms,
any of the above-mentioned elements may be present; but
if no precipitation  ensues, only sodium and potassium can
be present.
Acid.  The acidity may be cavused by a normnal salt
having an acid reaction, or by an acid salt.  Neither carbonates nor sulphides can be present ill an aqueous solution with an acid reaction.
Alcaline. The alkalinity may be due to the hydrates,
sulphides, cyanides, or carbonates, of the metals belong



~ s0          TESTING AN AQUEOUS'SOLUTION.          111
ing to Classes VI and VII; to the presence of a borate,
silicate, phosphate, arseniate, or aluminate of sodiuml  or
apotassium; to free ammonia, or carbonate of ammnonium.
If the alkalinity proceed from  an alkaline sulphide, the
metals whose sulphides are insoluble in water, and alkaline
sulphides, must be absent.  If it is clue to the presence
of the hydrates or carbonates of the metals of Classes
VI and VII, a very large number of substances are excluded.  If it proceed from  ammonia or carbonate of
aulmoniul, all, substances precipitable by these reagents
are abseint.
Au. allkaline solution may obviously contain some subst;ance, soluble in an alkaline solvent like caustic soda or
sulphydlrate of ammonium, but liable to immediate precipitation whlen this solvent is destroyed by the addition
of chlorhydric acid at the first step of the analysis.  Thus
any sulpbide of Class III dissolved in caustic soda, or an
alkaline sulphide, or colmpounds of alkaline hydrates with
tihe hydrates of aluminuml, zinc or chromiuml, would be
precipitated when the alkaline solvent was neutralized.
Chloride of silver dissolved in aammonia-water would be
thrown down by any acid added in excess.  Again, the
alkaline solution of a silicate of sodium  or potassium,
whlen neutralized with acid, yields a very gelatinous,
whitish precipitate of hydratedl silicic acid. From a very
concentrated solution of a borate, boracic acid separates
in colorless, shining, fiat crystals, when the solutioln is
acidified wit;h chlorhydric acid; but the boracic acid thus
separated dissolves when the solution is diluted.
In view of these possibilities, an alkaline aqueous solation should be carefully neutralized with nitric acid, as a
pwreliruinary mneasure, before chlorhydric acid is added to
it. Effervescen e should be wateched for, and if it occurs,
studied as directed in ~~ 53 —58.  Several diffferent cases




112                DISSOLVING IN ACIDS.              ~ 81
of precipitation may be distinguished, requiring somewhat different treatment.
a. If the characteristic gelatinous precipitate of silicic
acid appears, the acidulated solution must be evaporated
to dryness and ignited.  The silicic acid is thus rendered
insoluble.  The ignited residue is digested with dilute
nitric acid and filtered.  The filtrate is ready for the
usual course of analysis.  The insoluble residue is silicic
acid.
b. If the glistening, colorless plates of boracic acid
appear, dilution with warm  water will cause them  to
redissolve.
c. If a precipitate appear on neutralization, whose
color or texture proves that it is neither silicic nor boracic
acid, but some substance insoluble in water and dilute
acids, thrown down in consequence of the destruction of
its alkaline solvent, the liquid is made slightly acid, and
then filtered. The filtrate is ready for the usual course
of analysis. The precipitate, rinsed with a little water, is
reserved for further treatment; it is not properly a substance soluble in water, and it must be brought into
solution by other methods, hereafter to be described.
Sometimes a precipitate forms on exact neutralization of
an alkaline fluid, which redissolves when the acid is
added in excess.
81. Dissolving in acids.  The substance which water
has failed to dissolve, either in whole or in part, is next
boiled in a small dish with three or four times its bulk of
concentrated chlorhydric acid, unless the taube-test (~ 76)
or the reduction-test (~ 77) has proved the presence of
silver, lead, or mercury; in which case nitric acid is the




~ 81              DISSOLVING IN ACIDS.               113
first acid to be tried. (See the next paragraph.) If an
effervescence occur, the escaping gas is to be tested, as
described in ~~ 53-58. After boiling the powdered substance with the strong acid, dilute the fluid with twice its
bulk of water, and repeat the boiling if any residue
remain undissolved.  The acid is diluted because, though
the substance to be dissolved is best attacked in the first
instance by strong acid, the salts formed by the action of
the concentrated acid are more likely to dissolve readily
in a dilute than in a strong acid.  Not a few  salts
which  scarcely dissolve in strong  acids, are  readily
soluble in the same acids when diluted.  If the whole of
the substance finally dissolves, the solution still farther
diluted is ready for the transmission of sulphurettecl
hydrogen (~ 22), for it is of course unnecessary to examine it for members of Class I. If, on the contrary, an
undissolved residue remain in the tube, ascertain if anything has dissolved, by carefully evaporating two or three
drops of the fluid to dryness on platinum  foil.  Should
an appreciable residue, in excess of that given by two or
three drops of the acid employed, remain upon the foil,
separate the liquid in the tube from  the undissolvecd
substance by decantation or filtration.  Reserve the solution, labelling it " HC1 Sol."
Rinse the undissolved powder with water, and then
boil it in an evaporating dish with three or four times its
bulk of strong nitric acid. If the original substance
contained silver, lead, or a mercurous salt, chlorhydric
acid will not have been used, and it will be the residue
from the aqueous solution, which is now to be boiled with
nitric acid. In this case, effervescence is to be watched
for. If the substance dissolves completely in the strong
acid, or dissolves, with the exception of a light yellow
mass of sulphur, which often separates from a sulphide,




114                 AN ACID SOLUTION.                ~ 82
evaporate the liquid to a very s-mall bulk to drive off the
free acid, dilute the evaporated solution with several tiinmes
its bulk of water, separate the sulphur, if necessary, by
filtration, and reserve the solution, labelling it " HNO3
Sol."  If the substance does not completely dissolve in
the strong acid, dilute the fluid with twice its bulk of
water, and repeat the boiling.  If the dilute nitric acid
effects complete solution, reserve the solution, labelling it
as before, "1HNO3 Sol."  If neither the strong nor the
diluted nitric acid effects the complete solution of the
substance, ascertain if anything has dissolved in the
dilute acid by the usual test on platinum  foil.  If an
appreciable residue remain on the foil, separate the undissolved solid in the dish from the liquid by decantation
or filtration, and reserve the solution.
Boil the powder, which has resisted both acids taken
singly, with aqua-regia.  If it dissolves completely, evaporate the solution to a very small bulk, dilute the evaporated solution largely with water, and reserve it for
analysis, labelling it "Aq. reg. Sol."  It is useless to look
for members of Class I in such a- solution.  If, on the
contrary, it does not completely dissolve after protracted
boiling, test the liquor to see if anything has dissolved.
If an appreciable residue remains on the foil, dilute
the acid fluid, filter it, reserve the solution labelled as
before, and wash  the undissolved residue thoroughly
with water, to prepare it for fur-ther treatment (~ 83).
82. An acid solution.  Of the three linds of acid
solutions here described, any one, any two, or all three,
may be obtained from a single mixture of different solids.
There is an advantage in knowing that a part of a complex mixture is soluble in water, a part in chlorhydric
acid, a part in nitric acid, and a part only in aqua-regia;




~ 82              TESTING ACID SOLUTIONS.               115
because this knowledge may enable the student, when hoe
has found out all the elements of the mixture, to make a
more probable gness at the mann-mer of theiir combination
in the original mixture than he would otnerwise be able
to.  But it is quite unnecessary to keep the three kinds
of acid solution apart, when all three have been obtained,
and to analyze them  separately.  On the contrary, all
three should be mixed togetbher, and analyzed in one
course of testing.  It must only be borne in mind that
when lead, silver, or mercurous salts are present, the
nitric acidl solution of the residue from the aqueous solution will give a precipitate of the insoluble chlorides of
Class I, on being mixed with a chlorhydrie acid or aquaregia solution.
The student must be careful to use no more acid than
is absolutely essential.  Nitric acid, particularly, is very
objectionable; because, wh. en free, it reacts upon sulplh!uretted hydrogen with mutual deconiposition, s-lpp1i'hur beinig
set free.
Sometimes a strongly acid solution becomes turbid.
when  merely diluted with water.   This p'lleomenon
points to the preseince of bisniu;th or antimony.  The
turtybid4ity will disappear ag'ain on the acLdition of chlorhyd'Lic acid.
Certain silicates, whlen boiled  ithj conceO ntrated acids,
are decomposed, and gelatinous silicic acid. is separated.
This happens but rarely, however, in the rapid processes
01 qualitative  analysis;  and if it shLoul  happen, it is not
likely to lead the student into error.  A residue insoluble
in all acids will remain; this residue is, or contaiins, free
silicic acid.
It must not be supposed tal't it is comz1on l to try all
four solvents oni one aiid the same substance.  7T~ater ancl
chl] orhydric acid are the cominion solvents; nitric acid




116          SUBSTANCES INSOLUBLE IN ACIDS.         ~ 83
and aqna-regia are, actually, but seldom resorted to as
solvents, except for metals (~ 92). It would require
some ingenuity to devise an artificial mixture which
would put to the test all the capabilities of the abovedescribed method of bringing solids into solution in
water and acids.  Such mixtures are not met with in
ordinary experience.  It is the object of any imethod of
analysis to meet real problems, not artificial complications
which may be imagined, but which do not occur in fact.
C. TIEATMENT OF INSOLUBLE SUBSTANCES.
83. The substances of common occurrence which are
practically insoluble in water and acids are:The sulphates of barium, strontium, and lead.
Chloride of silver.
The anhydrous sesquioxides of aluminum, chromium,
and iron, either native or the result of an intense ignition.
Chrome-iron-ore, a native mlineral.
Somne aluminates.
Binoxide of tin, native, or the result of ignition.
Silica and many silicates.
F'luoride of calcium (fluor-spar).
Besides the substances included in this list, sulph-ur
and carbon, or graphite, should, perhaps, be mnentioned,
because they are insoluble; but they will have been detected during the preliminary blow-pipe examination, and
their presence allowed for. Bromide, iodide and cyanide
of silver, are decomlposed by boiling with aqua-regia, and
converted into the chloride, so that these substances
never appear in their proper form in the final insoluble
residue.




~ 84         SUBSTANCES INSOLUBLE IN ACIDS.        117
84. Substances which resist solution in liquids are
generally liquifiecd by the action of fluxes at a high temperature; they are fused in contact with some powerful
decomposing agent, like the carbonate or acid sulphate
of an alkali-metal, or the hydrate or carbonate of an
alkaline-earth metal. Certain preliminary experiments
should precede the fusion.
The insoluble powder is first examined carefully (with
the help of a lens, if convenient), to ascertain if it is a
homogeneous substance of the same color throughout, or
a mixture composed of dissimilar, variously-colored particles. The following blow-pipe experiments sometimes
give decisive indications, particularly with homogeneous
substances:a. The reduction-test (~ 77) is repeated with great
care, looking especially for silver, lead, and tin, and applying to the globule, if any is obtained, the test for distinguishing between these three white metals.  This test has
already been applied to the original substance; but if
this substance was a complex mixture containing soluble
ingredients, it is quite possible that the test should give
a more satisfactory result, now that all substances soluble
in water and acids have been removed, than it yielded
before. If any reducible metal is detected, it is necessary to use a porcelain crucible for the fusion which it
may be desirable to make (~ 85), in order to convert the
insoluble substance into a more manageable form. A
platinum  crucible, which is employed for most fusions,
cannot be used with safety when the substance to be
fused contains any reducible metal; for many of the
alloys of platinum are readily fusible.
Sometimes, when the substance under examination contains but a small proportion of metal, some metal may
6*




118          SUBSTANCEs INSOLUBLE IN ACIDS.         ~ 84
be redluced during the blow-pipe experiment on charcoal,
but the detached particles may not run together into a
single conspicuous globule.  Since a mistake as to the
presence of a reducible metal may involve the destlruction of a platinum  crucible, it is best, in doubtful cases,
to operate in a more delicate fashion.  To ascertainl, beyond question, whethser any reduced metal has been separated in this experiment, moisten the ca-vity in the charcoal with water after the fusion has been finished, cuAt the
charcoal out for a little distance, both aroundi and below
the cavity, and transfer the contents of the cavity ancd
the scraps of charcoal to an agate or porcelain mortar.
Pulverize the whole mass, and then carefully wash away
the powdered charcoal, and all the lighter portion of the
mixture.  Any malleable metal that may have been reduced remains in the mortar in little flattened grains or
spangles, in which the peculiar color and lustre of the
metal or alloy are generally visible.  Sometimes mentallic
streaks are produced on the mortar or pestle by little
particles of metal ground between them.  The student
must not mistake glistening particles of wet charcoal
sticking to the mortar or pestle for metallic spangles.
b. Prepare another pellet of a mixture of equal parts
of the insoluble powder and carbonate of sodiuon, addinga little charcoal powder to the paste. Fuse this mixture
upon charcoal in the redcucing flame of the blow-pipe.
Scoop out the fused] mass and the surrounding charcotal
with a penklnife, place thle dry mass upon a bright surface
of silver (coin or foil), and wet it with a drop of water.
If a brown stain be produced on the silver, it is evidence
of the presence of sulphidce of sodium in the fused mass.
This sulphide results from the reductioon of a sulphate,
and is evidence of the presence of a sulphate in the sub



~ 84         SUBSTANCECiS INSOLUBLE IN ACIDS.        119
stance tested.  The odor of sulphz-uretted hydrogen is
ofteln perceptible when the fused nmass is roi'stene. The
silver' coin or foil }may be replaced by a piece of leadpaper, if care be taken not to mistake'he mnere dirtying
of the paper for a stain of sulphide.  It is obvious that
the carbonate of sodium used in this test nust be so free
from silphate of sodium as not itself to give tlis reaction
on silver, after fusion on charcoal.  Since coal-gas invariably contains traces of sulphur compounds, this test
cannot be performed with a gas-flame.
c. Mfake the loop on the end of the bit of platinun
*wire (~ 168) white-hot in the blow-pipe flame, and thrust
it white-hot into sonme powdered borax; a quantity of
borax will adhere to the hot wire; reheat the loop in the
oxidizing flame; the borax will puff up at first, and then
fuse to a transparent glass. If enough borax to form a
solid, transparent bead within the loop does not adhere
to the hot wire the first time, the hot loop may be dipped
a second time into the powdered borax.
W~hen a transparent glass has been formed within the
loop of the platinum wire, touch the bead of glass while
it is hot and soft to a few  particles of the insoluble
powder, and reheat the bead with the adhering powder
in the oxidizing flame.  If the substance dissolves slowly
in the borax, and the bead has a fine yellowish-green
color when cold, chromium is probably present.  Rteheat
the bead in the reducing flame.  If it presents a bright
green color both when hot and cold, there is no doubt of
the presence of chrolninm.
It sometimes happens, when too nmuch of the substance 
to be tested has been added, that the borax bead becomes
so dark-colored as to be practically opaque.  It may then
be flattened, while soft, by sudden pressure betiveen any




120          SUBSTANCES INSOLUBLE IN ACIDS.        ~ 84
smooth metallic surfaces, like the flat parts of jewellers'
tweezers. If the flattening makes the color of the boraxglass visible, nothing more is necessary; but if the glass
is still too dark, all the glass outside the loop of platinum
may be broken off by gentle hammering, and the remaining glass may be reheated and largely diluted by the
addition of more borax.
It is convenient to be informed of the presence of
chromium, because chromic oxide and chrome-iron-ore
are substances which it is particularly difficult to decompose effectually by fusion. In presence of chromlium, no
other bead reaction which can be anticipated under the
circumstances will give a decisive result; but in the absence of chromiun, the presence of iron may be determined. A suitable quantity of oxide of iron causes the
borax-bead, heated in the oxidizing flame, to look red
when hot and yellow when cold. In the reducing flame
the iron bead becomes greenish, or light brownish-green.
d. The test for fluorine (~ 68) should be applied
to the original substance, if it has not already been
done.
When all the above-mentioned tests (a-d) give negative
results, the simplification of the problem  is very conspicuous; the substances which may be present are reduced to alumina and some aluminates, silica and silicates.
Ag'ain, when some of the preliminary tests give affirmative results, the evidence may be almost conclusive, if the
substcance under examination be evidently homogeneous.
Thus chloride of silver, sulphate of lead, chromic or ferric oxide, binoxide of tin, or fluoride of calcium, may be
satisfactorily identified.
There are two methods of changing insoluble subst1nces into maore manageable forms by the application of




~~ 85, 86             FUSIONS.                  121
heat, with sufficient exactness for the purposes of the
qualitative analyst,-the method by fusion, and the
method by deflagration.
85. Fusions. Mix the fine powder of the insoluble
substance with about four parts by weight of dry carbonate of sodium in powder. Both powders must be as fine
as they can be made, and they must be intimately mixed.
Keep the mixture at a bright red heat, in a platinum
crucible (a porcelain crucible if a reducible metal has
been found in the substance, and fusion is for any reason
preferred to deflagration), until the mass has been
brought to a state of quiet fusion (~ 164). Place the hot
platinum crucible, when withdrawn from the lamp or fire,
on a cold block, or thick plate of iron, and let it cool.
When the crucible has been cooled in this way, the fused
mass can generally be removed from the crucible in an
unbroken lump. Soak the lump in boiling water until
everything is dissolved which is soluble in water. If the
mass cannot be detached from the crucible, the crucible
and its contents must be soaked in boiling water.
When the green borax bead, and the dark color of the
insoluble powder, point to the presence of chrome-ironore, a mixture of two parts, by weight, of carbonate of
sodium with two parts, by weight, of nitre, may be substituted for the four parts of carbonate of sodium alone.
86. Treatment of the fused mass. The aqueous solution of the fused mass is filtered from the residue insoluble in water. Small portions of it are to be tested
separately at this stage of the process, for sulphate, chromate, chloride and fluoride of sodium, either of which
salts (besides others not regarded for the moment) may
result from the decomposition of the insoluble substance,




122               TESTING AFTERi FUSION.             ~ 86
and be found in the aqueous solution.  A chromate colors
the solution yellow.
a. Acidify a small portion witflh chlorhydric acid, and
test for sulphates with chloride of barium  (~ 62).  The
student must learn by trial how much sulphate, if any,
his carbonate of sodium contains.
b. Acidify another small portion with acetic acid, and
apply the acetate of lead test for chromates (~ 60). In
presence of sulphuric acid this test will be obscured, but
not rendered wholly useless (~ 29, p. 49).
c.  Acidify a third portion with nitric acid, and apply
the nitrate of silver test for chlorine (~ 69).  The student must first prove that his carbonate of sodium contains no chlorine.
d. A  fourth portion, having been concentrated by
evaporation in a porcelain dish, and again cooled, is acidified with chlorhydric acid, and then left at rest until tlhe
carbonic acid has escaped.  It is then supersaturated
with ammonia, heated, and filtered while hot.  The filtrate is collected in a bottle; chloride of calcium  is iminediately added to it; the bottle is closed and allowed
to stand at rest.  If the original substance contained a
fluoride, the fluorine will have combined with sodium
during the fusion, and fluoride of sodium will be contained in the aqueous solution.  The carbonic acid having been expelled, and all substances precipitable by
ammonia having been removed, the chloride of calcium
will throw clown the fluoride of calcium. If a precipitate
separates from the liquid in the bottle after some time, it
is collected in a sum'all filter, dried and examined for fluorine by the method of ~ 68.




~ 8I       FUSION WITHL BISULPEATE OF SODIUM.         123
The rest of the aqueous solution is acidifled wvitl chiorhydric acid, evaporated to dryness and  ignited; the
residue tihus obtained is boiled with dilute chlorhydric
aeid.  If the dilute acid fails to dcissolve the residue coipletely, the insoluble portion consists of silicic acid.  The
solution is reserved.
That portion of the original fused mass whlich boiling
water did not dissolve, and which was filtered froml  the
aqueous solution, is next dissolved in acid-c-hlorhydrie
acid, if silver and lead be absent; nitric acid, if either of
these metals be present —a-nd the solution so obtained,
mixed with the reserved solution of the last paragraph,
is examined in the usual way for the metallic elements
(~ 43), except;, of course, sodium (ancl sometimes potassium), which has been added in the flux.
If a portioll of the fused mass resist both water anld
acids, the insoluble portion may consist of separated
silicic acid, or of some of the original substance  ndclecomnposed by the fusion.  In the latter case, another and
nmore prolonged fusion is the only effectual remnedy, althlough it may often happen thllt a pa rtial decoimposition
of the insoluble substance will enable the analyst to
recognize all the elements which it contains.
87. Fusion wclith Acid Sul77hate of Sodimc.a.    The following nmethod may be tried to advantage -upon ferric
oxside, chromic oxide, or chrome-iron-ore, and some very
refractory silicates.  Heat the insoluble substance with
thlree or four timles its bulk of acid sulphate of sodiumn
(~ 122), in a platin-uim crucible, until the suilpate melts;
then nmaintain it in the liquid state for half an hour.
This operation should be perfor med under a hood.  The
fused ml:ass is treated essentially as before (~ 86), allownice being made for the different nature of the flux.




124            rUSION-TEST rFO  ALIALtES.      ~~ 88, 89
88$$. Silicates are by far the commonest of insoluble
salbstances. A great variety of metallic elements occur
in insoluble silicious minerals, so that the possible contents of the acid solution of ~ 86 are very various. When
silicic acid has been found in the aqueous solution of
~ 86, the acid solution also should be evaporated to dryness, after it has been once made, and the residue should
be ignited; the residual mass is again treated with dilute
chlorhydric acid. Silicic acid is again left behind in this
process; and the subsequent examination goes on the
better for this preliminary removal of silica, which, if left
in solution, might create confusion by appearing as a
precipitate at almost any stage of the analysis.
Many silicates contain sodium  and potassium.  When
the presence or absence of these alkali-metals is to be
determined, it is evident that the pulverized silicate must
not be fused with carbonate of sodium, but with some
decomposing flux free from alkali.
89. Fusion with Carbonate of Calcium and Chloride of
Ammonium.  An intimate mixture is prepared of one
part of the silicate, six parts of pure precipitated carbonate of calcium, and three-fourths part of pulverized
chloride of ammonium.  This mixture is heated to bright
redness in a platinum crucible for tihirty or forty minutes.
The crucible, with its contents (which should be in a coherent, sintered, but not thoroughly fused condition), is
then placed in a beaker, and soaked for half an hour in
water kept near the boiling point. The contents of the
beaker are then filtered. The filtrate, containing caustic
lime, chloride of calcium, and all the sodium and potassium of the original silicate as chlorides, is treated with
a little ammonia-water, and with carbonate of ammoniuw'
in slight excess; the liquid is heated to boiling and




~ 90        DECOMPOSITION BY DEFLAGRATION.         125
filtered.  This second filtrate is evaporated to dryness,
and gently ignited to expel the ammonium salts. The
residue is dissolved in a little water; one or two drops
of carbonate of ammonium, and a drop of oxalate of
ammllonium, are then added; the mixture is again heated
and filtered; this third filtrate is evaporated to dryness
and ignited; the ignited residue, if there be any, consists
of the chlorides of sodium  and potassium, or of one of
these two salts.  This residue is examined according
to ~ 41.
90. Deflagration. The method of fusion just described
involves the use of a platinum or porcelain crucible, and
demands the heat of a blast-lamp, or strong coal fire.
Neither crucibles, lamps, nor fires are necessary in the
method of defiagration, which applies the heat inside the
mass to be fused. This decomposition by deflagration is
performed as follows:-One part, by weight, of the insoluble powder is intimately mixed with two parts of dry
carbonate of sodium, two parts of fine and pure charcoal
powder, and twelve parts of powdered nitre.  The mixture is put in a thin porcelain dish, or clean iron tray;
the dish, or little tray, is placed under a hood, or in the
open air, and a lighted match is applied to the centre of
the heap. The deflagration is completed in two or three
seconds, and a well-fused mass remains. This mass is
detached from the cooled dish or tray, and boiled with
water in a beaker; it is generally very porous, and is
therefore readily disintegrated by stirring it in the hot
water with a glass rod. The soluble portion will all be
extracted in a very few minutes.  The residue left by
water is treated with acid precisely as described in ~ 86.
The aqueous and acid solutions of the deflagrated substance are submitted to the same operations as the cor



I2G        PRVEIIMINAJRY TREA'TMENT OF METALS.     ~ 91
responding solutions of substances fused in crucibles
(~ 86). A little charcoal is generally left unclissolved by
the acid, and with it any of the substance which. mnay
have escaped decomposition. The mixture of one part,
by weight, of powdered charcoal, and six parts of nitre,
may be kept ready mixed for effecting the fusion of insoluble substances.
The advantages of this process are that it is quick,
requires only cheap and common tools, and may be
applied to substances containing reducible mnetals, as well
as to any others. It is, of course, inapplicable when
sodium and potassium  are to be sought for in silicates.
Chrome-iron-or'e cannot be decomposed in this way. The
insoluble sulphates, chloride of silver, binoxide of tin,
fluorspar, glass, and many natural silicates, may be very
well treated by this method, in spite of its apparent
roughness.
CHAPTER XII.
TREATMi.ENT OF A PURE METAL OR ALLOY.
91..  The elements which are now used in the arts in
the metallic state, and which therefore may come into the
hands of the analyst as metals, either pure or alloyed,
are silver, lead, mercury, bismutth, cadmium, copper,
arsenic, antimony, tin, gold, platinum, aluminum, iron,
zinc, nickel, and magnesium. These metals can all be
brought into solution and detected in the wet way with
ease and certainty.  It is therefore not worth while to
submn-it a metal, or metallic alloy, to preliminary blowpipe
tests, although at need mercury antd  arsenic can be
readily detected by the closed-tube test (~ 76), and many




~ 92        ACeTION OF NITRIC ACID ON MEATALS.      127
thers, by exposing thlem  on charcoal to the reducing
and oxidizing flame (coupare ~ 77, p. 106).
A portion of the metal or alloy to be examlined should
first be reduced to as fine a state of division as possible.
If it is brittle, it can be powdered; if soft, shavings can
be eut from  it; if tough and hard, it can perhaps be
fused, and shaken into powder while melted, or granulated by beingo poured from  a height into cold water.
Filings should be the last resort, because of the possibility of foreign admixture of iron.
92. Action of  Titric Acid on the AMetals.  A  small
quantity of the divided metal or alloy, about the equivalent of a pea in bulk, is placed in a flask, covered with
concentrarted nitric acid, and heated gently under a hood
or in the open air for half an hour.
If complete solution ensues, gold, platinum, tinl, ancl  antimnony are probably altogether absent; they can only be
present inl very millnute proportion.  Ally of the other
nmetals above enumerated may be present.   Transfer thle
acid solution to a porcelain dish, and evaporate it almost
to dryness; dilute the evaporated liquid with five or six
times its bulk of water, and proceed with the analysis in
the usual way (~ 43).  If the solution becomes turbid on
the addition of water, bismluth is doubtless present.  In
this case enough acid must be restored to the solution to
clarify it.  Mercury, if present, will be dissolved to mercuric nitrate.
If a residue remains undissolved, add a little nlore acid,
to lmake sure that the acid is incapable of further action;
and when this point is settled, test a drop or two of the
clear liquid on1 platinum  foil, to ascertain if anytihing has
entlered into solution.  If the nitric acid has effected a
partial solution of the original metal, evaporate the liquid




128                 TEST FOR GOLD.                 ~ 92
nearly to dryness, dilate the evaporated mixture with
water, filter, and submit the filtrate to the usual course of
analysis.  The residue is thoroughly washed with water,
to prepare it for further treatment.  Three different cases
may occur, readily distinguishable by the mere appearance of the residue.
a. The insoluble substance is non-metallic and white.
In this case tin and antimony may be present, but gold
and platinum  are probably absent.  The white residue
may contain the insoluble oxides of tin and antimony, or
either of them. These elements are to be detected by
the methods of ~ 24, or by the method described just
below (first part of c).
b. The insoluble substance is metallic, as evidenced by
its lustre, if it is in visible fragments, or by the weight
and gray or black color of its powder, if it is in a fine
state of division.  Such a residue must be either gold or
platinum (or some of the rare platinum-like metals which
lie without the range of this manual). The residue is
dissolved in aqua-regia, and evaporated to a very small
bulk.
Test for Gold. A portion of this evaporated liquid is
diluted with ten times its bulk of water, anad poured into
a beaker which is placed on a sheet of white paper. A
small quantity of a solution of protochloride of tin
(~ 143) is tinged yellow by the addition of a few drops
of solution of sesquichloride of iron (~ 140), and then
considerably diluted. A glass rod is dipped, first into
this tin solution, and then into the solution to be tested
Test  for gold. If even a trace of the precious metal
for  be present, a blue or purple streak will be obAU. served in the track of the rod. If the quantity
of gold be more considerable, a pink tinge will be im



~ 92              TEST FOR PLATINUM.              129
parted to the solution, or a purplish precipitate will be
produced by a sufficient quantity of the tin-solution.
This " purple-of-Cassius" test is applicable to very acid
solutions.
Test for Platinum. To another undiluted portion of
the cooled aqua-regia solution, a cold concentrated solution of chloride of ammonium is added. The formation
of a yellow, crystalline precipitate of chloroplatinate of
Test ammonium  indicates the presence of platinum
for  (or of some rare platinum-like metal). By adding
Ots a little alcohol to the liquid, the test is made
more delicate. In a difficult case, the aqua-regia solution
might be evaporated to dryness with chloride of ammonium, and the residue treated with weak alcohol and
water, which would dissolve all the ingredients except
the chiloroplatinate.  Upon ignition chloroplatinate of
ammlonium leaves spongy platinum behind.
c. The insoluble residue contains both a white powder
and a metallic substance. It must then be examined for
antimony, tin, gold, and platinum. The following directions presuppose the presence of all four metals-a very
rare case.
The residue is placed in a porcelain dish in contact
with a slip of clean, smooth, platinum  foil, and heated
with a little chlorhydric acid. Water is then added, and
a small fragment of zinc is put into the liquid. Tin
and antimony will be reduced to the metallic state by the
zinc, and are detected by the method of ~ 24, p. 41. Gold
and platinum have been from  the first in the metallic
state, and do not interfere with the processes for detecting tin and antimony. When the antimony has been
extracted by tartaric acid, the platinum foil is taken out
of the porcelain dish, and the metallic residue from the




130       PRELIMINARY EXAteJINATION OF LIQUIDS.      ~ 93
tairtaric acid solution is thoroughly washed by decantatoi-, dissolved in aqua-regia, and tested for gold and plati:numn, as just described in ~ 92 b.
CIHIAPT EIt XIIIo
PEELIMINARY EXAMINATION OF A LIQUID.
83.  Evcporation Test.  The first step in the examnifna
tion of an unknown liquid is to evaporate a few drops at
a gentle heat on platinum foil. Attention should be paid
to the smell of the escaping vapors in order to ascertain
if the solvent be water or some other fluid, like alcohol,
ether, benzine, or a strong acid.  If no appreciable resicdue remlaill, the fluid is probably pure water, or solme
other volatile liquid; or it is possible that the liquic is
some very dilute solution, like a spring water, which
needs extreme concentration before the solid substances
dissolved in it can be detected.  When a residue remains
on the foil, the heat is increased, first, to ascertain if the
dissolved substances are wholly volatile, in which case
only compounds of ammomnilm, mercury, arsenic and
antimony, ca  be present; and, secondly, to ascertain if
tlhere be any organic matter in the liquid.  Carbonization
or charring, with the attendant phenomena (~ 76, I),
occurs when fixed organic matter is present.  If organic
matter is discovered, it must be destroyed by the second
method of ~ 76, I, before the analysis can be proceeded
with. A volatile organic solvent can, of course, be got
rid of by a simple evaporation to dryness.




~~ 94-96            TEST FOR AMDIONIA.                  131
94.  Testizg with Litm- s.  The next step is to test the
solution withl litmus-paper.
a. If it is nieutral, and tihe solvent is water, consult
~ so.
b.  If it is acid, the acidity may be due to a normal
salt having an acid reaction, or to an acid salt, or to free
acid.  No general inferences can be drawn from  the acid
reaction, except that carbonates and sulphides are absent.
If dilution of the acid  fluid  produces  turbidity, the
presence of antinnony or bismuth may be inferred.
c.  If it is alkaline, consult ~ 80 (Allcaline).
95.  By evaporating a' portion of the original solution
to dryness, the dissolved solid is obtained.  This solid
may be subjected to the whole of the prelimninary treatment prescribed for a salt, mineral, or other non-metallic
solid (~~ 76, 77); bnt inasmuch as the main object of all
prelinmindary treatment of a solid is to learn how to get it
into solution with the least difficulty, it is seldom  worth
while for the analyst to make a solid out of a soluLtion,
and thus foreg'o the acvantage of having the solution. already made to his hand.
86.  Testing for Ammonia.  A  small portion  of the
original solution nmust always be tested for ammonium
salts, by heating it in a test-tube with an equal b-lk of
slaked lime.  The gas is recognized by its smell and its
reaction with chlorhydric acid (~ 76).




132               TECHNICAL DETAILSo
The means of identifying and isolating the rare elements, the methods by which  minute traces of one
substance may be deetected when hidden in proportionally large quantities of other substances, as when the
impurities of chemicals and drugs are exhibited, and the
processes to be employed in special cases of peculiar difficulty, such as the analysis of complex insoluble minerals,
or the detection of mineral poisons in masses of organic
matter, must be studied in complete treatises upon chemical analysis, or in works specially devoted to these
technical matters.  Such details, however valuable to
the professional analyst, or expert, would not be in
harmony with the plan of this manual.




PART THIRD.
C IH APTER XIY.
REAG:ENTS.
[** Those reagents in the following list which are marked with the
double asterisk are rarely employed; a single small bottle of each
of them in the laboratory will be enough for many students.]
97. Chlorhydric Acid (Concentrated). The strong common acid prepared by chemical manufacturers, though
usually far from pure, will answer for most of the purposes of this manual. It must, however, be continually
borne in mind that the commercial acid is usually contaminated with sulphuric acid, and very often with traces
of arsenic and iron. These impurities may be present in
sufficient quantity to render the acid unfit for use when
these very substances are to be tested for in the mixture
to be analyzed.
The yellow color of the commercial acid, though often
attributed to iron, is really clue for the most part to the
presence of a peculiar organic compound which is soluble
in the strong acid.
Pure acid may be prepared by distilling a mixture of
fused chloride of sodium and sulphuric acid, and collect7




134:                  REAGENTS.            ~~ 98-102
ing the gas in water (see the anthors' Manual of Inorganic Chemistry, Exp. 49).
If in any experiment doubts arise concerning the character of a reagent, a quantity of it, somewhat larger than
that which has been mixed with the substance under examination, should be tested by itself, and the reaction
compared with that exhibited in the doubtful case. If the
result of this trial is unsatisfactory, the experiment must
be repeated with reagents which are known to be pure.
98.  Chlorhydric Acid (Dilute). Mix 1 volume of the
common concentrated acid, or-where special purity is
required-of the pure strong acid, with 4 volumes of
water.
99. Nitric Acid (Concentrated).  Use the colorless
commercial acid of 1.38 or 1.40 specific gravity. Strong
nitric acid of tolerable purity can usually be obtained
from the dealers in coarse chemicals. An acid, which
when diluted with five parts of water gives no decided
cloudiness with either nitrate of silver or nitrate of barium, is good enough for most uses in qualitative
analysis.
100. Nitric Acid (Dilute). Mix 1 volume of the strong
acid with 5 volumes of water.
101.  Aqua-regia should be prepared only in small
quantities, at the moment of use, by mixing in a test-tube
one volume of strong nitric acid, with three or four times
as much strong chlorhydric acid.
102. Sulphuric Acid (Concentrated). The oil of vitriol
of commerce will usually be found pure enough for the
purposes of this manual.




~~ 103-108            REAGENTS.                   135
103. Sulphuric Acid (Dilute) is prepared by gradually
adding 1 part of the concentrated acid to 4 parts of
water contained in a beaker or porcelain dish; the mixture must be constantly stirred with a glass rod. WThen
the mixing is finished, the liquid is left at rest until all
the sulphate of lead which has separated from the strong
acid has settled to the bottom; the clear liquid is then
decanted into bottles.
104. Oxalic Acid. Dissolve 1 part, by weight, of the
commercial crystals in 20 parts of water.
105. Acetic Acid. The ordinary commercial acid.
106.  Tartaric Acid should be kept in the state of powder, since solutions of it slowly decompose. For use, dissolve a small portion of the powder in two or three times
its volume of hot water.
107. Sulphuretted Hydrogen Gas (Sulphydric Acid) is
prepared, as needed, by acting upon fragments of sulphide of iron with dilute sulphuric acid in the apparatus
described in ~~ 178, 179. The apparatus should always
be placed either in the open air, or in a strong draught
beneath a chimney.
108. Sulphuretted Hydrogen Water. Pass sulphuretted
hydrogen gas into a bottle of water until the water can
absorb no more. To determine when the absorption is
complete, close the mouth of the bottle tightly with the
thumb, and shake the liquid. If the water is saturated,
a small portion of the gas will be set free by the agitation,
and a slight outward pressure against the thumb will be
felt. If the water is not fully saturated, the agitation




136                  REAGENTS.            ~~ 109, 110
will enable it to absorb the gas which lay in the upper
part of the bottle, and a partial vacuum will be created,
so that an inward pressure will be felt.
Since sulphuretted hydrogen water soon decomposes
when exposed to the air, it should always be kept in
tightly closed bottles; and no very large quantity of it
should be prepared at once. A good way of keeping the
solution is, to fill a number of small phials with the fresh
liquid, cork them tightly, and invert them in water, so
that their necks shall always be immersed and protected
from the atmosphere.
At the moment of using this reagent, its quality should
always be proved by smelling of it, or by adding a drop or
two of the liquid to a drop of acetate of lead.
109.  Ammonia- Water.  Commercial aqua-ammonime
may usually be obtained pure enough for the purposes of
this manual. Dilute 1 volume of the strong liquor with
3 volumes of water. Ammonia-water should be free
from carbonic acid; when diluted, as above, it ought not to
yield any precipitate when tested with lime-water.
110. Sulphydrate of Ammonium. Pass sulphuretted
hydrogen gas through ammonia-water, diluted as described in ~ 109, until a portion of the liquid yields no precipitate when tested with a drop of a solution of sulphate
of magnesium.
Since sulphydrate of ammonium decomposes after a
while, when exposed to the air, it is not advisable to prepare it in large quantities. In case any doubt arises as
to the quality of the reagent, add some of it to a drop of
acetate of lead. Unless a dense, black precipitate of
sulphide of lead is immediately thrown down, the sulphydrate is worthless.




~~ 111-116            REAGENTS.                   137
111. Carbonate of Ammonium. Dissolve 1 part, by
weight, of the commercial salt in 4 parts of water, and
add to the mixture 1 part of strong ammonia-water.
112.  Chloride of Ammnonium.  Dissolve 1 part, by
weight, of the crystallized commercial salt in 10 parts of
water.
113. Oxalate of Ammonium. Dissolve 1 part, by weight,
of the salt in 24 parts of water.
114. Nitrate of Ammonium. The commercial salt,
kept as dry as possible, in the form of small crystals.
115. ** Molybdate of Anzmonium. Digest 1 part, by
weight, of molybdic acid for some hours in 4 or 5 parts of
strong ammonia-water, and mix the clear solution with 12
or 15 parts of strong nitric acid; or dissolve 1 part of
molybdate of ammonium in 3 or 4 parts of weak ammonia-water, and mix the liquid with 12 or 15 parts of
nitric acid, as before.
116.  Caustic Soda. Place 1 part, by weight, of the
best commercial caustic soda in a large stoppered bottle;
pour upon it 8 or 9 parts of water, and shake the bottle
at intervals, until the whole of the soda has dissolved.
Leave the bottle at rest until the liquid has become clear,
and finally transfer the solution, with a siphon, to the
small bottles in which it is to be kept for use. The solution thus prepared, though pure enough for the uses prescribed in this manual, is really far from pure. It would
be unfit for use in a delicate research, because it is usually
contaminated with chloride, sulphate and carbonate of
sodium, and is liable to contain traces of aluminate,




138                  REAGENTS.            ~~ 117, 118
phosphate, and silicate of sodium. Since some nitrate of
sodium is added to it in the process of manufacture, the
soda is liable to be contaminated with this salt and the
products of its decomposition, including ammonia. This
last impurity is liable to be given off when the solution is
boiled.
Caustic potash, as prepared for surgeons' use, may be
substituted for caustic soda whenever it can be more
readily obtained. The potash should be dissolved in
about 10 parts of water.
Since solutions of the caustic alkalies act upon glass
rather easily, especially when its outer surface or C" fireglaze " has once been removed, it often happens, when the
soda solution is kept in glass-stoppered bottles, that the
stoppers become immovably cemented to the glass by the
silicate of sodium which forms in their necks. This difficulty may be avoided by wiping the necks of the bottles
dry after any of the solution has been poured from them;
but it will usually be found more convenient to replace
the glass stoppers with plugs of vulcanized caoutchouc,
or, better still, with small glass stoppers, over the bodies
of which short pieces of caoutchouc tubing have been
stretched.
117.  Sulphydrate of Sodium.  Dissolve 1 part, by
weight, of commercial sulphide of sodium in 8 parts of
water. Sulphide of potassium is not an available substitute for sulphide of sodium.
118. Carbonate of Sodium. The anhydrous salt of commerce will answer for most uses. It should not contain
much sulphate of sodium. For those cases in which the
use of carbonate of sodium, free from any contamination
of sulphate, is prescribed, the salt may be prepared by




~~ 119-124            REAGENTS.                   139
washing a pound or two of bicarbonate of sodium  repeatedly upon a filter, with small quantities of ice-cold
water, until the original quantity is reduced to a fifth or
a sixth of its bulk.
119. Biborate of Sodium. Common borax, powdered.
120. Nitrate of Sodium. Select a white, clean sample
of the commercial salt, and dissolve 1 part, by weight, in
3 parts of water.
121.  Dip hosphate of Sodium.  Dissolve 1 part, by
weight, of " common phosphate of soda" in 10 parts of
water.
122. ** Acid Sulphate of Sodium. Heat a mixture of
16 parts, by weight, of Glauber's salt, and 5 parts of concentrated sulphuric acid, in a platinum  vessel, until a
portion of the melted mass becomes distinctly solid when
taken up on a glass rod. Then allow the mixture to become cold; remove the cold lump from  the platinum
vessel, and break it into fragments. Keep the coarse
powder in a tight, glass-stoppered bottle.
123. Sulphate of Potassium. Dissolve one part, by
weight, of the crystallized salt in 200 parts of water.  A
solution of this strength contains the same proportional
quantity of sulphuric acid as is contained in a saturated
aqueous solution of sulphate of calcium. Hence it cannot precipitate the latter when added to solutions of the
soluble calcium salts.
124.  Chromate of Potassium.  (The normal or "neutral" yellow chromate.)  Dissolve 1 part, by weight, of
the salt in 8 parts of water.




140                    REAGENTS.            ~~ 125-129
125..Ferrocyanidc of Potassium.  (Yellow Prussiate of
Potash.)  Dissolve I part, by weight, of the commercial
salt in 12 parts of water.
126. ** Ferricyanide of Potassium.  (Red P'russiate of
Potash.)  Since the aqueous solution of this salt undergoes decomposition, with formation of some ferrocyanide,
when kept for any length of time, the salt should be kept
for use in the form  of powder. The commercial salt is
pure enough for analytical purposes. A minute fragment
of it may be dissolved in water at the moment of use.
127. ** Cyanide of Potassium.  The better sorts of
the commercial article are pure enough for analytical
purposes. It should be kept in the solid form, in a
tightly stoppered bottle. When the solution is required,
dissolve 1 part of the salt in 4 parts of cold water.
128. Nitrate of Potassium.  Refined saltpetre may be
employed. It should be kept in the state of powder.
129. ** Nitrite of Potassium.  Weigh out 8 parts of
concentrated nitric acid, mix it with an equal weight of
water, and place the mixture in a glass flask provided
with a perforated cork and gas delivery-tube.  The flask
should be so large that the mixture only half fills it.
Throw into the liquid two parts of starch, in lumps, and
heat the mixture until red fumes of nitrous and hyponitric acids begin to be given off; then remove the lamp
lest the action become too violent. Conduct the fumes
into a bottle containing 5 parts of potash-lye of 1.27 sp.
gr., until the latter is saturated. Then filter the saturated liquid, and evaporate it to dryness.  For use,
dissolve 1 part of the dry salt in 2 parts of water.




~~ 130133             REAGENTS.                   141
The nitrite of potassium  bought of dealers in fine
chemicals is often unfit for the uses prescribed in this
manual; it can readily be made good, however, by dissolving it in water, in the proportion above given, and
saturating the solution with nitrous fumes.
130. ** Iodide of Potassium and Starch Pap2ers. Dissolve a gramme of pure iodide of potassium  (free from
iodate) in 200 cubic centimetres of water. Heat the
solution moderately in a porcelain dish, and stir into it
ten grammes of starch which has been reduced to the
consistence of cream by rubbing it in a mortar with a
small quantity of water. Stir the mixture until it gelatinizes, taking care not -to burn the starch, then allow the
paste to cool, and spread it thinly upon one side of white
glazed paper with a wooden spatula. Dry the paper, cut
it into strips as large as the little finger and preserve it
in stoppered bottles kept carefully closed.
131. Nitrate of Silver. Dissolve 1 part, by weight, of
the commercial crystals in 20 parts of water.
132. Slaked Lime. Mix common quicklime with half
its weight of water. Keep the powder in bottles with
tight stoppers.
133. ** Lime Water. Place a handful of slaked lime
in a large bottle, pour in enough water to almost fill the
bottle, cork the latter tightly, and shake it at intervals
during several days. Decant the clear liquid into smaller
bottles for use. Refill the large supply-bottle with water,
and again shake it at intervals.
134.  Chloride of Calcium. Stir powdered white marble into dilute chlorhydric acid until the acid is saturated,
7*




142                   REAGENTS.            ~~ 135-139
and dilute 1 part of the concentrated solution with 5
parts of water.
135.  Chloride of Barium. Dissolve 1 part, by weight,
of the commercial salt in 10 parts of water.
136. ** Nitrate of Barium. Dissolve 1 part, by weight,
of the commercial salt in 15 parts of water.
137. Acetate of Lead. Dissolve 1 part, by weight, of
"sugar of lead " in 10 parts of water.
138. Lead-paper. VTet strips of white paper in a solution of acetate of lead, or better, in a solution of subacetate of lead, and dry them in air which is free from sulphuretted hydrogen. Cut the dried paper into slips as
large as the little finger, and keep the slips in tightly
stoppered bottles. Or, paper may be slightly moistened
with a solution of acetate of lead at the moment of use.
139. Sulphate of Magnesium and Chloride of Ammonium.
Dissolve 24.6 grammes of Epsom salt and 33 grammes of
commercial chloride of ammonium  in water, add some
ammonia-water to the solution and dilute the liquor to
the volume of a litre. If less than a litre of the reagent
is required, the weights above given may, of course, be
reduced in any desired proportion. Filter the solution to
separate any precipitate of ferric hydrate or other insoluble matters which may have been present as impurities
in the components of the mixture, and preserve the clear
liquid.
From a solution thus prepared no hydrate of magnesium can be precipitated by ammonia-water; herein consists the advantage of the mixture as a test for phosphoric and arsenic acids.




~~ 140-146             REAGENTS.                   143
140. ** Ferric Chloride. This solution is prepared by
passing chlprine gas through a saturated solution of iron
tacks in chlorhydric acid, until a drop of the fluid no
longer produces a blue precipitate in a solution of ferricyanide of potassium. The solution is then heated to
expel the excess of chlorine.
141. ** Nitrate of Cobalt. Dissolve 1 part, by weight,
of the crystallized salt in 10 parts of water..142. ** Sulphate of Copper.  Dissolve 1 part, by
weight, of the crystallized salt (blue vitriol) in 10 parts
of water.
143. ** Protochloride of Tin. This solution is prepared
by boiling scraps of tin with strong chlorhydric acid
until hydrogen ceases to be evolved. The tin must be in
excess. The solution is diluted with four times its bulk
of water acidulated with ehlorhydric acid, and filtered, if
necessary. The clear liquid must be kept in a tightly
closed bottle containing some bits of tin.
144. ** Bed Oxide of Iercury.  The  commercial
oxide. It should leave no residue when heated upon
platinum foil.
145. -** Chloride of Mercury. Dissolve I part of "corrosive sublimate" in 16 parts of water.
146. ** Bichloride of Platinum. Cut a small quantity
of worn-out platinum foil into very fine pieces and boil
them in a porcelain dish, with successive small portions of
aqua-regia (~ 101), until all the metal has been dissolved.
Collect the several portions of aqua-regia, partially satu



144                   REAGENTS.            ~~ 1z17-150
rated with platinum, in another dish, and evaporate the
liquid to dryness on a water bath. Dissolve the residue
in 10 parts of water for use.
147. ** "Solution of Indigo" (Suiphindigotic Acid).
Pour 5 parts (5 grammes will be ample) of fuming sulphuric acid into a beaker, place the latter in a dish of
water to keep it cool, and stir into the acid, little by
little, 1 part of finely powdered indigo. When all the
indigo has been added to the acid, leave the mixture at
rest for 48 hours; then pour it into 20 times its own
volume of water, filter the mixture, and preserve the filtrate for use.
148. Litmus Paper. Heat 1 part, by weight, of commercial litmus with 6 parts of water, upon a water bath
for several hours, taking care to replace the water which
evaporates.  Filter, divide the filtrate into two equal
portions, and stir one-half repeatedly with a glass rod
dipped in very dilute nitric acid, until the color appears
distinctly red.  Pour the blue and red halves into a
porcelain dish, and stir the mixture.  Draw  strips of
fine unsized paper through the liquid, and hang them on
cords to dry. The color of the paper thus obtained is
not blue, but bluish-violet. It turns blue when touched
with an alkali, and red when exposed to acids, and may
be used indifferently as a test for either acids or alkalies.
149.  Turmeric Paper. Digest 1 part, by weight, of
bruised turmeric in 6 parts of warm spirits of wine.
Filter the tincture and steep in it narrow strips of white
paper. The dried paper should have a fine yellow color.
150. Starch Paste should be prepared, when wanted for
use, by boiling 30 cubic centimetres of water in a porce



~~ 151, 152            UTENSILS.                   145
lain dish, and stirring into it half a gramine of starch
which has previously been reduced to the consistence of
cream  by rubbing it in a mortar with a few drops of
water.
151.  TTWater. Clean rain-water will serve well enough
for most of the purposes of this manual. In granitic
regions the water of many lakes, brooks, and ponds also,
is nearly pure. Pure water may be obtained by melting
blocks of compact ice, or by distilling ordinary water in
glass or copper retorts and rejecting the first portions
of the distillate.  It should yield no precipitate when
tested with chloride of barium and nitrate of silver.
CHAPTER XV.
UTENSILS.
152. The implements required by the  student of
qualitative analysis are few and simple. Besides bottles
for the reagents enumerated in the foregoing list, and a
few small phials for the preservation of samples of salts
and mixtures to be analyzed, there will be needed:A dozen test-tubes,       A gas-bottle for generating
A wooden test-tube rack,    sulphuretted hydrogen,
A test-tube brush,        A  common jewellers' blowA nest of small beakers,    pipe,
2 or 3 glass stirring-rods,  A pair of small iron pincers
3 small glass fuannels,     (jewellers' tweezers),
1 small glass flask,      A piece of platinum foil,
1 wash-bottle,            A bit of platinum wire,




146               REAGENT BOTTLES.              ~ 153
2 small evaporating dishes, A few packages of cut filters
1 porcelain crucible,      or a quire of filter paper,
1 triangle of iron wire,   A few corks or caoutchouc
An iron ring-stand,        stoppers,
A filter-stand,          A piece of blue cobalt glass
A lamp,                  (see ~ 41).
153. Reagent Bottles. The bottles in which reagents are
kept should be of cylindrical shape, and rather high
than wide. They should be closed with glass stoppers
which fit accurately, but are not very finely ground. The
stoppers should have upright (not mushroom-shaped)
heads. Most of the liquid reagents may be conveniently
kept in narrow-mouthed bottles of the capacity of 6 fluid
ounces; but to avoid the necessity of frequently refilling
the bottles, it is well to keep the solutions most commonly
employed-namely, dilute chlorhydric and nitric acids,
caustic soda, ammonia-water, chloride of ammonium, and
carbonate of ammronium —in 8-ounce bottles. Care must
be taken in this case to choose bottles of such shape that
they can be readily grasped between the thumb and
fingers.
For the reagents which are to be kept in the dry state,
wide-mouthed bottles of the capacity of 2 or 3 ounces
should be chosen.
Reagent bottles should always be made "e extra-heavy,"
since, from constant use, they are exposed to many blows.
The lustrous " flint-glass bottles " of American or English
make are ill suited for the preservation of liquid reagents;
for such glass is easily attacked by many chemical agents,
and is therefore likely to render the reagents impure.
German bottles are usually to be preferred. They are
made of glass free from lead, have round shoulders and
well-ground stoppers, and are often numbered both upon




~ 154             REAGENT BOTTLES.              147
the bottle and the stopper, so that the proper place of the
latter can always be discovered. French bottles, though
made of good glass and sold at a low price, have usually
such square shoulders that it is well nigh impossible to
empty them completely, and often difficult to pour out a\
liquid from them drop by drop. Their stoppers, moreover, are usually too finely ground, and are hence constantly liable to stick fast.
Each reagent bottle should be kept in a particular
place on shelves before the operator and convenient to
his hand. Whenever a reagent is to be used, the bottle
which contains it should be grasped in the right hand;
the stopper should be taken out by pinching it between
the first and second, or third and fourth, fingers of the
left hand, or by pressing it between the little finger
and palm of that hand.  In either case, the bottle is
withdrawn from the stopper, and not the stopper from
the bottle. Neither bottle nor stopper should be put
upon the table; the stopper should be held in the left
hand as long as the bottle is open. When the reagent
has been poured out, the bottle is immediately closed,
and returned to its own place upon the shelf. If these
apparently trifling particulars are scrupulously attended
to, no stopper can ever be misplaced, or soiled by
contact with liquids or dirt on the table; and the
bottle will always be found in its proper place when
instinctively reached for. Moreover, the label on the
bottle cannot be injured by drops of the reagent, since
the liquid must necessarily be poured from the back, or
blank, side of the bottle.
154. When a stopper sticks tightly in the neck of a
bottle, it may sometimes be loosened by pressing it first
upon one side, and then upon the other, with the thumb




148                 TEST-TUBES.                ~ 155
of the right hand, while the fingers of that hand grip the
bottle, and the bottle is held still with the left hand. Or
the neck of the bottle may be immersed in hot water for
a minute or two, to expand the glass outside the stopper.
The stopper can then usually be taken out without
trouble. The hot water may be conveniently applied by
pouring a slow stream of it from a wash-bottle upon the
neck of the bottle. Another way is to heat the neck of
the bottle over a very small flame of the gas or alcohol
lamp. No matter how the glass is heated, the bottle
must be constantly turned round and round, in order
that each side of the neck may be equally exposed to the
heat, and the risk of cracking the bottle so be lessened.
155. Test-tubes are little cylinders of thin glass with
round thin bottoms and lips slightly flared. Their length
may be from five to seven inches, and their diameter from
one-half to three-fourths of an inch; they should never
be so wide that the open end cannot be closed by the ball
of the thumb.
Test-tubes are used for heating small quantities of
liquid over the gas or spirit-lamp; they may generally be
held by the upper end in the fingers without inconvenience; but in case they become too hot to be held in
this way, a strip of thick folded paper may be nipped
round the tube, and grasped between the thumb and forefinger just outside the tube.
Two precautions are invariably to be observed in heating test-tubes:-lst. The outside of the tube must be
wiped perfectly dry; and 2nd. The tube must be moved
in and out of the flame for a minute or two when first
heated. It should be rolled to and fro also to a slight
extent between the thumb and forefinger, in order that
each side of it may be equally exposed to the flame. A




~~ 156, 157            FLASKS.                    149
drop of water on the outside of the tube keeps one spot
cooler than the rest. The tube breaks, because its parts,
being unequally heated, expand unequally, and tear apart.
When a liquid is boiling actively in a test-tube, it sometimes happens that portions of the hot liquid are projected out of the tube with some force; the tube should
therefore always be held in an inclined position, and the
operator should be careful not to direct it towards himself, or towards any other person in his neighborhood.
Test-tubes are cleaned by the aid of cylindrical brushes,
made of bristles caught between twisted wires, like those
used for cleaning lamp-chimneys; the brushes should
have a round end of bristles.
156.  Test-tube Bach. Test-tubes are kept in a wooden
rack, such as is represented in Figure 1. When in use,
the tubes stand upright in the
holes of the rack; but clean tubes      Fig. 1.
are inverted upon the pegs behind 
the holes, in order that they may
be kept free from  dust, and that    Iliu _
the last portions of wash-water c~   ~ 
may drain away from them after
washing.  The rack should be
large enough to hold a dozen tubes,
157..Flaslcs.  Small Berlin flasks, of two or three
ounces capacity, are well suited for the purposes of qualitative analysis. These German flasks are tough, capable
of withstanding sudden changes of temperature, and
durable, although their bottoms and sides have all the
requisite thinness. When a liquid is to be boiled in a
flask, the flask should be placed upon a support of wiregauze (~ 165), and sufficiently inclined, to prevent any




150                   FILTERING.           ~~ 158-160
particles of the liquid from being thrown out of the neck
by the movement of ebullition.
As with test-tubes, and all other glass or porcelain vessels, of whatever form, the outside of a flask must be
wiped perfectly dry before exposing it to the lamp. The
flame should be moved about also beneath the flask, at
first, in order that the temperature of the latter may be
raised equally and not too rapidly.
158. Beakers are thin, flat-bottomed tumblers, with a
slightly flaring rim. They are bought in sets or nests.
A nest in which the largest-sized beaker has a capacity of
about 6 ounces will be sufficient for the requirements of
this work.
159. Glass Funnels should be thin and light, and
should be about 2 or 2.5 inches in diameter. Their sides
should incline at an angle of 60~. The wider the throat
of the funnel the better.
160. Filtering. Paper filters are employed in qualitative analysis to separate precipitates from the liquids in
which they have been formed. A good filtering-paper
must be porous enough to filter rapidly, and yet sufficiently close in texture to retain the finest powders; and
it must also be strong enough to bear, when wet, the
pressure of the liquid which is poured upon it. Filterpaper should never contain any gypsum or other soluble
material, and should leave only a small proportion of
ash when burned. White or light-gray paper is to be
preferred to colored, since it more commonly fulfils these
requirements.
Filtering-paper is commonly sold in sheets, which may
be cut into circles of any desired diameters for use, ac



~ 160                  FILTERS.                   151
cording to the various scales of operation and quantities
of liquids to be filtered. Or packages of "cut-filters"
may be procured ready-made from the dealers in chemical
wares.
As a general rule, small filters should be employed in
analytical operations; the mixture to be filtered should
be poured, by small successive portions, upon a filter no
larger than is needed to hold the whole of the solid
matter which is to be collected. Filters about three
inches in diameter are well suited for most of the analytical operations described in this work, though there
are many cases where smaller filters are required, and a
few instances in which filters as large as four inches in
diameter might be necessary.
There are two ready methods of preparing filters for
use. According to the first method, shown in Fig. 2, a
circle of paper is folded
Fig. 2.    over on its own diameter,    Fig. 3.
v      and the senmicircle thus obtained is folded once upon
itself into the form  of a
quadrant; the paper thus
folded is opened so that
three  thicknesses  shall
come upon one side, and
one thickness upon the
other, as shown in the upper half of Fig. 2; the filter is
then placed in a glass funnel, the angle of which should
be precisely that of the opened paper, viz., 60~. The
paper may be so folded as to fit a funnel whose angle is
more or less than 60~; but this is the most advantageous
angle, and funnels should be selected with reference to
their correctness in this respect.
In the second method of folding filters, the circle of




152                  FILTER-STAND.                ~ 161
paper is doubled once upon itself, as before, into the form
of a semicircle, and a fold equal to one quarter of this
semicircle is turned down on each side of the paper.
Each of the quarter semicircles is then folded back upon
itself, as shown in the lower half of Fig. 3; the filter is
opened, without disturbing  the folded portions, and
placed in the funnel. Filtration can be rapidly effected
with this kind of filters, for the projecting folds keep
open passages between the filter and the funnel, and thus
facilitate the passage of the liquid. That portion of the
circle of paper, which must necessarily be folded up in
order to give the requisite conical form to a paper filter,
retards filtration in the first manner of folding, but helps
it in the second.
A filter should always be moistened with water after it
has been placed in the funnel, in order that the fibres of
the paper may be swollen and the size of its pores diminished, before any of the matter to be filtered can pass
into them.
Coarse and rapid filtration —as in the preparation of
reagents-can be effected with paper filters of large
size, or with cloth bags; also by plugging the neck of a
funnel or leg of a siphon loosely with tow or cotton. If
a very acid or very caustic liquid, which would destroy
paper, cotton, tow, or wool, is to be filtered, the best substances wherewith to plug the neck of the funnel are
asbestos and gun-cotton, neither of which is attacked by
such corrosive liquids.
161. Filter-Stand.  Filters less than two inches in
diameter may be placed directly in the mouth of a
test-tube without need of even a funnel to support them;
and in general the funnel which holds a filter may be
thrust directly into the mouth of a test-tube whenever




~ 162           DISHES AND CRUCIBLES.             153
the quantity of liquid to be filtered is small, if only an
ample exit be provided for the air in the    Fig. 4.
tube, in the manner shown with the bottle
of Fig. 4.
But when the quantity of liquid to be
filtered is comparatively large, or the operations to which the filtrate is to be subjected
require that it should be collected in a
beaker or porcelain dish, the funnel should
have an independent support.  The iron
ring-stand, described in ~ 165, may be used
for this purpose in case of need; but wooden stands of
the form represented in Fig. 5, adapted expressly for
holding funnels, are very convenient and not expensive.
The horizontal bar which holds the funnel may be fixed
at any height on the vertical square rod by means of a
wedged-shaped key, whose form is shown in the figure.
A fine-grained wood, which does not swell or shrink
much, is desirable for filter-stands.
Fig. 5.          In general, care should be
taken that the lower end of
the funnel touch the side or
edge of the vessel into which
the filtrate descends, in order
that the liquid may not fall in
drops, but run quietly without splashing.
162. Porcelain Dishes and
Crucibles. Small open dishes
which will bear heat without
cracking, are much used for
boiling and evaporating liquids. The best evaporating-dishes are those made of




154:             DISHES AND CRUCIBLES.          ~ 162
Berlin porcelain, glazed both inside and out, and provided with a little lip projecting beyond the rim. The
dishes made of Meissen porcelain are not glazed on the
outside, and are not so durable as those of Berlin manufacture; but they are much cheaper, and with proper
care last a long time.
The small Berlin dishes, Nos. " 00," "0," and "1," are
well suited for all the requirements of this work. They
will generally bear an evaporation to dryness and subsequent ignition over the open flame of a gas lamp-as
when ammonium salts are expelled from Class VII (~ 41)
-but it is well to protect the dish somewhat by placing
it upon a piece of wire-gauze, rather than to support it
upon a simple triangle. The Meissen dishes do not so
well endure an open flame. The cheaper kinds of evaporating dishes, made of "semi-porcelain," should never
be subjected to this severe treatment; they are, for that
matter, unfit for use in qualitative analysis.
Very thin, highly glazed porcelain crucibles, with glazed
covers, are made both at Berlin and at Meissen near
Dresden. In general the Meissen crucibles are thinner
than the Berlin, but the Berlin crucibles are somewhat
less liable to crack; both kinds are glazed inside and
out, except on the outside of the bottom. The Berlin,
Nos. " 00" and "0," respectively 1 1-4 and 1 1-2 inches
in diameter, are best suited for the purposes of this
manual. As the covers are much less liable to be broken
than the crucibles, it is adveatageous to buy more crucibles than covers, whenever it is possible so to do. Porcelain crucibles are supported over the lamp on an iron
wire triangle; they must always be gradually heated, and
never brought suddenly in contact with any cold substance while they are hot.




~ 163                  LAMPS.                    155
163. Lamps. The common spirit-lamp will
be understood without description, from the   Fig. 6.
figure (Fig. 6). When not actually lighted,
the wick must be kept covered with the glass
cap; for if the wick were exposed to the air,
the alcohol in the spirit upon it would evaporate faster than the water, and the cotton
would soon become water-soaked and incapaable of being lighted.
Whenever gas can be obtained, gas-lamps are greatly
to be preferred to the best spirit-lamps. For all ordinary
uses, the gas-lamp known as Bunsen's burner may be employed. The cheapest and best construction of the lamp
may be learned from the following description with the
accompanying figures.  (Fig.
Fig. ~i       7.) The single casting  of
brass a b comprises the tube b
through which the gas enters,
and the block a from which
the gas escapes by two or
three fine vertical holes passXd    b    I)       ing through  the screw  d,
afelqri/)~_ >      and issuing from  the upper
face of d, as shown at e. The
length of the tube b is 4.5 c.
im., and its outside diameter
varies from 0.5 c. m. at the outer end to 1 c. m, at the
junction with the block a. The outside diameter of the
block a is 1.6 c. m., and its outside height without the
screws is 1.8 c. m. By the screw c, the piece a b is attached to the iron foot g, which may be 6 c. m. in diameter. By the screw d, the brass tube f is attached to the
casting a b. The diameter of the face e, and therefore the
internal diameter of the tube f, should be 8 m. m. The




156           BLAST LAMPS AND BLOWERS.           ~ 164
length of the tube f is 9 c. cm. Through the wall of this
tube, four holes 5 m. m. in diameter, are to be cut at such
a height that the bottom of each hole will come 1 m. m.
above the face e when the tube is screwed upon a b.
These holes are of course opposite each other in pairs.
The finished lamp is also shown in the figure. To the
tube b a caoutchouc tube of 5 to 7 m. in. internal diamneter is attached; this flexible tube should be about 1 m.
long, and its other extremity should be connected with
the gas-cock through the intervention of a short piece of
brass gas-pipe screwed into the cock.
In cases where a very small flame is required, as, for
example, in evaporating small quantities of liquid, a piece
of wire-gauze somewhat larger than the opening of the
tube f should be laid across the top of the tube, and its
projecting edges pressed down tightly against the side of
the tube, before the lamp is lighted. In default of this
precaution, the flame of a BunFig. 8.        sen's burner, when small and
exposed to currents of air, is
liable to pass down the tube,
and ignite the gas at d.
164. Blast-lamps and Blouwers. Though well suited for
all the ordinary operations of
the  laboratory, the  lamps
b I    Ad ~ above described are incapable
of yielding a very intense heat.
Hence, when the contents of a
a                    platinum  crucible are to be
fused or intensely heated, a
blast-lamp will be found useful. The best form is that sold under the name of Bun



~ 161         BLAST LAMPS AND BLOWTERS.             157
sen's Gas Blowpipe. Its construction and the method of
using it may be learned from the accompanying figure;
a b is the pipe through which the gas enters, c is the tube
for the blast of air; the relation of the air-tube to the external gas tube is shown at d; there is an outer sliding tube
by which the form and volume of the flame can be regulated.
If gas is not to be had, a lamp burning oil or naphtha
may be employed. Figure 9 represents a common tin,
glass-blower's lamp, suitable for
burning oil. A large wick is            Fig. 9.
essential, whether oil or naphtha be the combustible.  
For every blast-lamp a blowing machine of some sort is
necessary.  To supply a constant blast it is essential that the bellows be of that construction called double. Figures 10 and 11 represent two
forms of blowpipe-table; their height is that of an
ordinary table, from  which dimension the other proportions may be inferred. A small double-acting bellows is
made (formerly used by dentists), which is available at
any table by the help of a caoutchouc tube to conduct the
blast to the jet. These bellows are
too small to give a steady flame of      Fig. 10.
large size, but will, nevertheless,
answer for most of tie glass-blow-  
ing necessary in the execution of            1
the experiments described in this
manual.
Where an abundant supply of
water is at command, the following
blowing apparatus is very convenient: A tin pipe a b (Fig. 12),
about 1 metre long and 13 11. m.




158            BLAST LAMPS AND BLOWERS.            ~ 164
in diameter, has two smaller pipes, 12 to 16 c. m. long,
soldered into it; these small pipes are 8 m. m. in diameter; one, c d, is inserted at right angles 12 c. ln. fron
the end, the other, ef, 2.5 c. m. lower, -at an angle of 45~.
The lower end of the tube passes through the cork of a
Fig. 11.                          Fig. 12.
wide-mouthed  ten-litre bottle, extending rather more
than half way down.  Two glass tubes also pass through
the cork of the bot[tle-a short small tube g, No. 4, (~ 171)
which should reach some 16 c. m. above the cork, but
should not project into the bottle, and a larger tube ih,
No. 2, extending to the bottom of the bottle. The outer
end of the tube /i bends over, and is connected by
caoutchone tubing with a straight tube of eqcal diameter.




~ 164s            I-IATINGI CORUCIBLES.             159
This last arrangement fornms the siphon. To the tube g
a caoutchouc tube, g i, is attached to convey the blast to
any desired point. To produce a blast, the water-cock is
connectecl with the tube c d by means of a caoutchouc
tube. When the water is turned on, the caoutehoue tube
g i is closed for a moment with the thumb and finger.
This starts the water through the siphon, and iminediately a continuous and powerful blast of air rushes out
through the tube g i, and may be carried directly to the
blow-pipe. The siphon must be capable of carrying off a
larger stream of water than that which is allowed to enter,
so that there shall never be more than 3 or 4 c. m1. of
water in the bottle. By regulating the water-cock, the
proper supply of water may be determined.
The same apparatus may be used as an aspirator. W7hen
the instrument is to be used to draw air through any apparatus, the upper end of the tube a b is closed with a cork,
and the tube e f is connecte   with the apparatus through
which the current of air is to be drawn. The force of
the current of air is to a certain degree affected by the
size of the tiuLbe a b; to diminish the effective calibre of
this tube, in case a gentle current of air is required, a
glass rod as long as the tube may be passed down the
tube through a cork inserted at a. The samle apparatus
nay thus be made to produce a gentle or a powerful current of air.
In cefault of a blast-lamp, jplatintnm  crucibles may
readily be ignited in a fire of coke or anthracite.  To this
end, place the tightly covered platinum  crucible in a
somewhat larger crucible of refractory clay-or Hessian'wvare, and pack the space between the two crucibles
tightly with calcined magnesia, so that the platinum may
nowlhere conme in contact with the clay. Cover t1he coarse
crucible, and place it, with its contents, in the coal fire,




160                HEATING CIRUCIBLES.            ~ 161
inll such a manner that it may be gradually heated; finally,
imbeci the crucible in the glowing coals and urge the
draught of the furnace for half an hour. The degree of
heat to which the contents of the platinum crucible may
be exposed in this way in an efficient fire, is really far
greater than that of the blast-lamps above described; but
the lamps are more convenient than the fire.
The effect of a simple Bunsen's bburner nay be greatly
increased without the use of any blower, by surrounding
its flame with a cylinder of fire-clay, 3 inches in diameter
by 4 or 5 inches high, and having, walls at least - of an
inch thick. The crucible, or other body to be heated,
is hung' in the middle of this chimney, and is thus
exposed not only to the direct heat of the flame, but
also to the radiant heat from  the clay walls which surround it.
Where no gas is to be
Fig. 13,          had, an  alcohol lamp
-with circular wick, of
some one of the nmnerous forms sold under the
nlame of Berzelius's Argand Spirit La-mnp (Fig.
13), will be found useful.;__p' __              These arg'and lamps are
1usually mounted  on z
j _ laimp-stand provided with
three brass rings; but
the  fiLtinogs  of  these
lamps are all made slender, in order not to carry
off too much heat. When
it is necessary to heat hea-vy vessels, other supports must
be used.




~~ 165, 166    IRON-STAND —WATER-BATH.              161
165. Iron-stand, Tripod, Wire-gauze, and Triangle. To
support vessels over the gas-lamp, an iron-stand is used,
conllsisting of a stout vertical rod fastened into a heavy,
cast-iron foot, and three iron rings of graduated sizes
secured to the vertical rod with binding screws; all the
rings may be slipped off the rod, or any ring may be
adjusted at any convenient elevation. The general arrangement is not unlike that of the stand which makes
part of the Berzelius lamp (Fig. 13), although simpler
and cheaper. As a general rule, it is not best to apply
the direct klame of the lamp to glass and porcelain vessels; hence a piece of iron wire-gauze of medium fineness
is stretched loosely over the largest ring, and bent downwards a little for the reception of round-bottomed vessels.
On this gauze flasks and porcelain dishes are usually
supported. Crucibles, or dishes, too small for the smallest
ring belonging to the stand, are conveniently supported
on an equilateral triangle made of three pieces of soft
iron wire twisted tog-ether at the apices; this triangle is
laid on one of the rings of the stand. An iron tripodthat is, a stout ring supported on three legs-may often
be used instead of the stand above described, but it is not
so generally useful because of the difficulty of adjusting it at various heights; with a sufficiency of wooden
blocks wherewith to raise the lamp or the tripod as occasion may require, it may be made available.
166.  Waler-bath and Sand-bath. It is often necessary
to evaporate solutions, or to dry precipitates at a moderate temperature which can permanently be kept below a
certain known limit. Thus, when an aqueous solution is
to be quietly evaporated without spitting or jumping, the
temperature of the solution must never be suffered to rise
above the boiling point of water, nor even quite to reach




162                   WATE-BATH.                  ~ 166
this point. This quiet evaporation is best effected by the
use of a water-bath —a copper cup whose
Fi'g. 1~4. top is made of concentric rings of different diameters, to adapt it to dishes of
chi p     various size (Fig. 14). This cup, twothirds full of water, is supported on the
Q  iron-stand over the laimp, aznd the dish
containing the solation to be evaporated
is placed on that one of the several rings
which will permit the greater part of the dish to sink into
the copper cup. The steam rising firom the water impinges
upon the bottom of the dish, and brings the liquid within
it to a temperature which insures the evaporation of the
water, but will not cause any actual ebullition.  The
water in the copper cup must never be allowed to boil
away. Wherever a constant supply of steam is at hand,
as in buildings warmed by steam, the copper cup above
described may be converted into a steam-bath, by attaching it to a steam-pipe by means of a small tube provided
with a stop-cock.
A cheap but serviceable water-bath may be made from
a quart milk-can, oil-can, tea-canister, or any similarly
shlaped tin vessel, by inserting t'he stem  of a glass funnel
into the neck of the can through a well-fitting cork. In
this funnel the dish contaiDning the liquor to be evaporated
rests. The can contains the water, which is to be kept
just boiling.  On account of the shape of the funnel,
dishes of various sizes can be used with the same apparatus.
When a gradual ancd equable heat, higher than can be
obtained upon the water-bath, is required, a sand-bath
will sometimes be found useful. A cheap and convenient
sand-bath may be imade by beating a disk of thlin sheetiron, aboaLt four inches in diamleter, into the form of a




~ 167                 BLOW-PIPE.                   163
saucer or shallow pan, and placing within it a small quatntity of dry sand. The dish or flask to be heated is imbedded in the sand, and the apparatus placed upon a
ring of the iron-stand over a gas-lamp.
67. Blo0w-p pe. The cheapest and best form of mouth
blow-pipe for chemical purposes is a tube of tin-plate,
about 18 c. in. long, 2 c. m. broad
at one end, and tapering to 0.7 c.       Fig. 15.
m. at the other (Fig. 15); the
broad end is closed, and a little...._.
above this closed end a small
cylindrical tube of brass about 5
c. m. lon-g is soldered in at right
angles; this brass tube is slightly
conical at the end, and carries a
small nozzle or tip, which may be
made either of brass or platinum. 
The tip should be drilled out of a solid piece of metal,
and should not be fastened upon the brass-tube with a
screw. A trumpet-shaped mouth-piece of horn or boxwood is a convenient, thoucgh1 by no means essential addition to this blow-pipe.
The blow-pipe may be used with a candle, with gas, or
with any hand-lamp proper for burning oil, petroleum, or
any of the so-called burning fluids, provided that the
form of the lamp below the wick-holder is such as to permit the close approach of the object to be heated to the
side of the wick. WVhen a lamp is used, a wick about 1.2
c. m. long and 0.5 c. m. broad is more convenient than a
round or narrow wick; a wick of this sort, though hardly
so wide, is used in some of the open burning-fluid (naphtha) lamps now in common use. The wick-holder should
be filed off on its longer dimension a little obliquely, and




164                  BLOw-PIPE.                ~ 167
the wick cut parallel to the holder, in order that the blowpipe flame may be directed downwards when necessary
(Fig. 16). A gas flame suitable for the blow-pipe is
readily obtained by slipping a narrow brass-tube, open at
both ends, into the tubef of Bunsen's burner.  (See Fig.
7.) This blow-pipe-tube must be long enough to close
the air apertures in the tube f, and should be pinched
together and filed off obliquely on top, as shown in Fig.
16; it may usually be obtained with the burner from
dealers in chemical ware.
To use the miouth blow-pipe, place the open end of the
tin tube between the lips, or, if the pipe is provided with
a mouth-piece, press the trumpet-shaped mouth-piece
against the lips; fill the mouth with air till the cheeks
are widely distended, and insert the tip in the flame of a
lamp or candle; close the communication between the
lungs and the mouth, and force a current of air through
the tube by squeezing the air in the mouth with the
muscles of the cheeks, breathing, in the meantime, regularly and quietly through the nostrils. The knack of
blowing a steady stream for several minutes at a time is
readily acquired by a little practice. It will be at once
observed that the appearance of the flame varies considerably, according to the strength of the blast and the position of the jet with reference to the wick.
FWhen the jet of the
Fig. 16.      sblow-pipe is inserted
into the middle of a
candle-flame, or  is
placed in the lamp-` —z-:  flame in the position
shown in Fig. 16, and
a strong blast is forced
throug'h the tube, a




~ 167       OXIDIZING AND NEDUCING FLAME.          165
long, blue cone of flame, a b, is produced, beyond and
outside of which stretches a more or less colored outer
cone towards c. The point of greatest heat in this
flame is at the point of the inner blue cone, because
the combustible gases are there supplied with just the
Lquantity of oxygen necessary to consume them, but
between this point and  the extremity of the flame
the  comabustion  is concentrated  and  intense.  The
greater part of the flame thus produced is oxidizing
ill its effect, and this flamie is technically called the oxidizingflame. From the point a of the inner blue cone, the
heat of the flame diminishes in both directions, towards b
on the one hand, and towards c on the other; most substances require the temperature to be found between a
anc c. Oxidation takes place most rapidly at, or just beyond, the point c of the flame, provided that the temperature at this point is high enough for the special substance
to be heated.
A flame of precisely the opposite chemical effect may be
produced with the blow-pipe.  To obtain a good 1reduzcing
flame, it is necessary to place the tip of the blow-pipe, not
within, but just outside of the flame, and to blow rather
over than through the middle of the flame (Fig. 17). In
this manner the flame is less altered in its general character than in the former
case, the chief part con-           Fig 17
sisting of a large, lumfinous cone, containing a quantity of free
carbon in a state of
intense  ignition, and
just in the condition for
taking up oxygen. This
flame is, therefore, reo:




166            PLATIJNUM FOIL AND WIRE.           ~ 168
dacing in its effect, and is technically called the redulcing
flame. The substance which is to be reclueed by exposur e- to this flame, should be completely covered up by
the luminous cone, so that contact with the air may be
entirely avoided. It is to be observed that, whereas to
produce an effective oxidizing flame a strong blast of air
is desirable, to get a good reducing flame the operator
should blow gently, with only enoulgh force to divert the
lamp-flame.
Substances to be heated in the blow-pipe flame are
supported, sometimes on charcoal, and sometimes on
platinum foil or wire, or in platinum  spoons or forceps.
Charcoal is especially suitable for a support in experiments of reduction.
163. Platinum foil and wire.  Piceers.  A piece of
platinum foil about 1, inches long and 1 inch wide will
be sufficient. The foil should be at least so thick that it
does not crinkle when wiped; and it is more economical
to get foil -which is too thick thlan too thin, for it requires
frequent cleaning. To keep foil in good order it should
be frequently scoured with fine moist sand, and in case
the foil becomes wrinkled it may be burnished by placing
it upon the bottom  of an inverted agate or porcelain
mortar and rubbing it strongly with thle pestle.
A bit of platinum  wire, not stouter than the wire of a
small pin and about 3 inches long, will last a long time
with careful usage. It may be cleaned by long-continued
boiling in water. A small loop about as large as this 0,
should be bent at each endc of the wire.
~When platinum foil is to be heated it may be held at
one end with a pair of the small steel pincers known as
jewellers' tweezers. A piece of platinum  wire, as long as
the one above described, can be held in the fingers with



~~ 169, 170 PLATINUM CRUCIBLES-WASH-BOTTLE.          167
out inconvenience, for platinum  is, comparatively speaking, a bad conductor of heat. Pieces of wire too short
to be held may be made serviceable by thrusting one end
of the wire into the end of a glass rod or closed tube
which has been softened in the blow-pipe flame.
169. Platinum  Grucibles.  For several of the operations of quantitative analysis as now practised, platinum
crucibles are indispensable, and though not absolutely
necessary for the profitable study of qualitative analysis,
one of these vessels will offten be found convenient by
the student of the elements of analysis.  It will be well,
therefore, for the student who proposes to continue his
chemical studies beyond qualitative analysis, to procure
a platinum crucible once for all. A crucible of the capacity of about 20 cubic centimetres will be large enough
for most uses; it should be cylindrical rather than flaring,
and should be provided with a loose cover in the form of
a shallow dish.
No other metal, and no mixture of substances from
which a metal can be reduced, must ever be heated in a
platinum  crucible, or upon platinum foil or wire, for
platinum forms alloys with other metals which are much
more fuasible than itself. If once alloyed with a baser metal,
the platinum ceases to be applicable to its peculiar uses.
Platinum may be cleaned by boiling it in either nitric
or chlorhydric acid, by fusing acid sulphate of sodium
upon it, or by scouring it with fine sand.  Aqua-regia
and chlorine-water dissolve  platinum; the sulphides,
cyanides, and hydrates of sodium  and potassium, when
fused in platinum vessels, slowly attack the metal.
170.  Wash-bottle.  A  wash-bottle is a flask with a
uniformly thin bottom, closed with a sound cork or caout



168                 GLASS TUBING.               ~ 171
ehouc stopper through which pass two glass tubes, as
shown in Fig. 18.
The outer end of the loncger tube is drawn
Fig. 18.  to a moderately fine point. A short bend
near the bottom  of this longer tube, in the
same plane and direction as the upper bend,
is of some use, because it enables the operator
to empty the flask more completely by inclining it. By blowing into the short tube,
a stream of water will be driven out of the
long tube with  considerable force.  This
force with which the stream  is projected
\  _/ Sadapts the apparatus to removing precipitates from the sides of vessels as well as to
washing them  on filters. For use in analytical operations, it is often convenient to attach a caoutchouc tube
12 or 15 c. m. long to the tube through which the air is
blown; this flexible tube should be provided with a glass
mouth-piece, consisting of a bit of glass tubing about 3
c. m. long. As the wash-bottle is often filled with hot or
even boiling water, it may be improved by binding about
its neck a ring of cork, or winding the neck closely with
smooth cord. It may then be handled without inconvenience when hot.
The method of making a wash-bottle is described in
the following paragraphs.
171. Glass Tubing. Two qualities of glass tubing are
lused in chemical experiments: that which softens readily
in the flame of a gas or spirit-lamp, and that which fuses
with extreme difficulty in the flame of the blast-lamp.
These two qualities are distinguished by the terms soft
anld hard glass. Soft glass is to be preferred for all uses
except the intense heating, or ignition, of dry substances.




~~ 172, 173   CUTTING AND CRACKING GLASS.            169
[Fig. 19 represents the common sizes of glass tubing, both
hard and soft, and shows also the proper thickness of the
glass walls for each size. The numbers ranging fromn 4
to 8 are best suited for use in qualitative analysis.
Fig. 19.
8  7   6   5   4       3        2          1
172.  Stirring Rods.  Cut a short stick of glass rod,
No. 8 or 7, into pieces four or five inches long (see the
next paragraph), and round the sharp ends by fusion in
the blow-pipe-flame.
173.  Cutting, and craclcing glass.  Glass tubing and
glass rod must generally be cut to the length required
for any particular apparatus.  A sharp triangular file is
used for this purpose.  The stick of tubing, or rod, to be
cut is laid upon a table, and a deep scratch is made with
the file at the place where the fracture is to be made.
The stick is then grasped with the two hands, one on
each side of the mark, while the thumbs are brought together just at the scratch.  By pushing with the thumbs
and pulling in the opposite direction with the fingers, the
stick is broken squarely at the scratch, just as a stick of
candy or dry twig may be broken.  The sharp edges of
the fracture should invariably be made smooth, either
with a wet file, or by softening the end of the tube or
rod in the lamp (~ 174).  Tubes or rods of sizes four
to eight inclusive may readily be cut in this manner; the
larger sizes are divided with more difficulty, and it is




170           CUTTING AND CRACKING GLASS.            ~ 173
often necessary to make the file-mark both long and
cdeep.  An even fracture is not always
Fig. 20.   to be obtained with large tubes.  The
lower ends of glass funnels, and those
ends of gas delivery-tulbes which enter
the bottle or flask in which the gas is
generated, should be filed off or ground
off on a grindstone, obliquely (Fig. 20),
to facilitate the dropping of liquids from such extremities.
In ordcer to cut glass plates, the glazier's diamoncl must
be resorted to.  For the cutting of exceedingly thin
glass tubes, and of other glass ware, like flasks, retorts,
andl bottles, still other means are resorted to, based upon
the sudden and unequal application of heat.  The process
divides itself into two parts,-the producing of a crack in
the required place, and the subsequent guiding of this
crack in the desired direction.  To produce a crack, a
scratch must be made with the file, and to this scratch a
pointed bit of red-hot charcoal, or the jet of flame produced by the mouth blow-pipe, or a very fine gas-flame,
or a red-hot glass-rod, or iron wi-re, may be applied.
If the heat does not produce a crack, a wet stick or
file may be touched upon the hot spot.  Upon any
part of a glass surface except the edge, it is not possible to control perfectly the direction andcl extent of
this first crack; at an edge a small crack may  be
started  with  tolerable  certainty by carrying the  file
nzark entirely over the edge.  To guide the crack thus
started, a pointed bit of charcoal or slow-match may
be used.  The hot point must be kept on the glass
from 1 c. mn. to 0.5 c. m. in advance of the point of
the crack.  The cr"ack will follow the hot point, and mnay
therefore be carried in any desired direction.  By turan



~ 174      BENDING AND CLOSING GLASS TUBES.          171
ing and blowing' upon the coal or slow-imatch, the point
may be kept sufficiently hot.  Whenever the place of
experiment is supplied with common illuminating gas, a
very small jet of burning gas may be advantageously
substituted  for the hot coal or slow-match. To obtain
such a sharp jet, a piece of hard glass tube, No. 5, 10 c.
m. long, and drawn to a very fine point (~ 174), should
be placed in the caoutchouc tube, which ordinarily delivers the gas to the gas-lamp, and the gas should be
lig-hted at the fine extremity.  The burning jet should
hLave a fine point, and should not exceed 1.5 c. mn. in
length. By a judicious use of these simple tools, broken
tubes, beakers, flasks, retorts, and bottles may often be
made to yield very useful articles of apparatus.  [No sharp
edges should be allowed to remain upon glass apparaitus.
The cadurability of the apparatus itself, and of the corks
ancd caoutchouc stoppers and tubing used with it, will be
miuch greater, if all sharp edges are removed with the
file, or still better, rounded in the lamp.
174. Bentding and closing glass tubes. Taubing of sizes
folur to eight inclusive, can generally be worked in the
comumon gas or spirit-lamp; for larger tubes the blastlamp is necessary (~ 164).  Glass tubing must not be
introduced suddenly into the hottest part of the flame,
lest it crack. Neither should a hot tube be taken from
the flame and laid at once upon a cold surface.  Gradual
heating and gradual cooling are alike necessary, ancd are
the more essential the thicker the glass; very thin glass
will sometimes bear the most sudden changes of temperature, but thick glass and glass of uneven thickness
absolutely require slow heating and anneatling.  Whoen
the end of a-tube is to be heated, as in rounding sharp
edges, more care is required in consequence of the great




172        BENDING AND CLOSING GLASS TUBES.     ~ 17i
facility with which cracks start at an edge. A tube
should, therefore, always be brought first into the current
of hot air beyond the actual flame of the gas or spiritlamp, and there thoroughly warnmed, before it is introduced into the flame itself. If a blast-lamp is employed,
the tube may be warmed in the smoky flame, before the
blast is turned on, and may subsequently be-annealed in
the same manner; the deposited soot will be burnt off in
the first instance, and in the last, may be wiped off when
the tube is cold. In heating a tube, whether for bending,
drawing, or closing, the tube must be constantly turned
between the fingers, and also moved a little to the right
and left, in order that it may be uniformly heated all
roundc, and that the temperature of the neighboring
parts may be duly raised. If a tube, or rod, is to be
heated at any part but an end, it should be held between
the thumb and first two fingers of each hand in suclh a
manner that the hands shall be below the tube or rod,
with the palms upward, while the lamp-flame is between
the hands. When the end of a tube or rod is to be
heated, it is best to begin by warming the tube or rod
about 2 c. m. froml the end, and from thence to proceed
slowly to the end.
The best glass will not be blackened or discolored
during heating. Blackening occurs in glass which, like
ordinary flint glass, contains oxide of lead as an ingredient. Glass containing much of this oxide is not well
adapted for chemical uses. The blackening may sometimes be removed by putting the glass in the upper or
outer part of the flame, where the reducing gases are
consumed, and the air has the best access to the glass.
The blackening may be altogether avoided by always
keeping the glass in the oxidizing part of the flame.
Glass begins to soften ancl bend below a visible red




~ 174       ENDING AND CLOSING GLASS TUBES.      173
heat. The condition of the glass is judged of as much
by the fingers as the eye; the hands feel the yielding of
the glass, either to bending, pushing, or pulling, better
than the eye can see the change of color or form. It may
be bent as soon as it is hot enough to yield in the
hands, but can be drawn out only when much hotter
than this. Glass tubing, however, should not be bent at
too low a temperature; the curves made at too low a
heat are apt to be flattened, of unequal thickness on the
convex and concave sides, and brittle.
In bending tubing to make gas-delivery tubes and the
like, attention should be paid to the following points:
ist, the glass should be equally hot on all sides; 2d, it
should not be twisted, pulled out, or pushed together
during the heating; 3d, the bore of the tube at the bend
should be kept round, and not altered in size; 4th, if two
or more bends be made in the same piece of tubing
(Fig. 21, a), they should all be in the same plane, so that
the finished tube will lie flat upon the level table..When a tube or rod is to be bent
Fig. 31.    or drawn close to its extremity, a
temporary handle may be attached
to it by softening the end of the
tube or rod, and pressing against
the soft glass a fragment of glass
tube, which will adhere strongly to the softened end.
The handle may subsequently be removed by a slight
blow, or by the aid of a file. If a considerable bend is
to be made, so that the angle between the arms will be
very small or nothing, as in a siphon, for example, the
curvature cannot be well produced at one place in the
tube, but should be made by heating, progressively,
several centimetres of the tube, and bending continuously from one end of the heated portion to the other




174         BENDING AND CLOSING GLASS TUBES.       ~ 174
(Fig. 21, b).  Smal1 and thick tube mnay be bent more
sharply than large or thin tube.
In order to draw a glass tube down to a fillner bore, it is
simply necessary to thoroughly soften on all sides one or
two centimetres' length of the tube, and then takinSg the
glass friom the flame, pull the parts asunder by a cautious
movement of tile hands.  The larger the heated portion
of glass, the longer will be the trlbe thsus formred.  Its
leng'th and fineness also increase withi the rapidity of motion of the hands. If it is desirable that the finer tube
should have thicker walls in proportiol to its bore than
t;he original tube, it is only necessary to keep the heated
portion soft for two or three minuntes before drawing out
the tube, pressing the parts slightly together the while.
By this process the glass will be thickened at the hot
ring.
To obtain a tube closed at one end, it is best to take a
piece of tubing, open at both ends, and long enouglh to
make two closed tubes.  In the mliddle of the tube a ring
of glass, narrow as possible, nmust be made trlorounghly
soft. The hands are then separated a little, to cause a
contraction in diameter at the hot
and soft part.  The point of the           Fig. 22.
flianre must now be directed, not  -.
upon the narrowest part of the tube,
but upon what is to be the bottomr of
the closed tube.  This point is indiated by the line a in Fig. 22. By withdrawing the right
l hand, the narrow part of the tube is attenuated, and fillally
nelted off, leaving  both halves of the original tube
closed at one end, but not of the same fornm; the righthandcl half is drawn out into a lolng point, the other is
more roundly closed.  It is not possible to close handsoreely the two pieces at once.  The tube is seldom per



~ 175               BLOWING BULBS.                   175
feetly finished by the operation; a superfluous knob of
glass generally remain-s upon the end.  If small, it may
be got rid of by heating- the whole end of the tube, and
blowing moderately wfith the mouth into the open end.
Thle knob, being' hotteor, and thereforo softer than any
other part, yields to thle pressurie fromn within, spreads
out and disappears.  If the krnob is large, it may be cut
off with scissors while red hot, or drawn off by sticking
to it a frag'ment of tube, and then softening' the glass
above the junction.  The same process nmay be applied
to the too pointed end of the right-hand half of the
original tube, or to any misshapen result of an unsuccessful attempt to close a tube, or to any bit of tube which is
too short to make two closed tubes. W~hen the closed
end of a tube is too thin, it may be strengthened by
keeping the whole end at a red heat for two or three
minutes, turning the tube constantly between the fingers.
It may be said in general of all the preceding operations
before the lamp, that success depends on keeping the.
tube to be heated in constant rotation, in order to secure
a uniform temperature on all sides of the tube.
175.  Blovwing Bulbs. Bulb-tubes, like the one represenlted in Fig. 23, are employed for reducing substances
capable of forming sublimates upon the cold walls of the
tube. They are readily made
Figr. 23.:romn bits of tubing, in the
flame of Bunsen's burner, or
in  the  common  blow-pipe
flame.
If the bulb desircld is larg'e
in proportion to the size of
the tube on which it is to be made, the walls of the tube
must be thicokened by rotation in the flame before the




178                BLOWING BULBS.              ~ 175
bulb can be blown. The thickened portion of the glass is
then to be heated to a cherry-red, suddenly withdravwn
from  the flame, and expanded while hot by steadily
blowing, or rather pressing, air into the tube with the
mouth; the tube must be constantly turned on its axis,
not only while in the flame, but also while the bulb is
being' blown. If too strong or too sudden a pressure be
exerted with the mouth, the bulb will be extremely thin,
and quite useless. By watching the expanding glass, the
proper moment for arresting the pressure may usually be
determined. If the bulb obtained be not large enough,
it may be reheated and enlarged by blowing into it again,
provided that a sufficient thickness of glass remain.
If a bulb is to be blown in the middle of a piece of
tubing, the thickening is effected by gently pressing the
ends of the tube together while the glass is red-hot in
the place where the bulb is to be; if a large bulb is to be
placed at thle end of a tube, this end is first closed, and
then suitably thickened by pressing the hot glass up
with a piece of metal until enough has been accumulated
at the end.
It is sometimes necessary to make a hole in the side of
a tube or other thin glass apparatus. This lmay be done
by directing a pointed flame from the blast-lamp upon
the place where the hole is to be, until a small spot is
red-hot, and then blowing forcibly into one end of the
tube while the other end is closed by the finger; at the
hot spot the glass is blown out into a thin bubble, which
bursts or may be easily broken off, leaving an aperture in
the side of the tube.
It is hoped that these few directions will enable the
attentive student to perform, sufficiently well, all the
manipulations with glass tubes which the experiments
described in this manual require. Much practice will




~ 176                CAOUTCHOUC.                   177
alone give a perfect mastery of the details of glassblowing.
178.   aoutcchouc. Vulcanized caoutchouce is a most
useful substance in the laboratory, on account of its elasticity, and because it resists so well most of the corrosive
substances with which the chemist deals. It is used in
three forms: (1) in tubing of various diameters comparable with the sizes of glass tubing; (2) in stoppers of
various sizes, to replace corks; (3) in sheets. Caoutchouc tubing may be used to conduct all gases and liquids
which do not corrode its substance, provided that the
pressure under which the gas or liquid flows be not
greater, or their temperature higher, than the texture of
the tubing can endure. The flexibility of the tubing is
a very obvious advantage in a great variety of cases.
Short pieces of such tubing, a few centimetres in length,
are much used, under the name of connectors, to make
flexible joints in apparatus of which glass tubing forms
part; flexible joints add greatly to the durability of such
apparatus, because long glass tubes bent at several angles
and connected with heavy objects, like globes, bottles or
flasks full of liquid, are almost certain to break, even with
the most careful usage; gas-delivery tubes, and all considerable lengths of glass tubing, should invariably be
divided at one or more places, and the pieces joined again
with caoutchouc connectors. The ends of glass tubing
to be thus connected should be squarely cut, and then
rounded in the lamp, in order that no sharp edges may
cut the caoutchouc; the internal diameter of the caoutchouc tube must be a little smaller than the external diamneter of the glass tubes; the slipping on of the connector is facilitated by wetting the glass. In some cases




178                   CAOUTCIIOUC.                 ~ 176
of delicate quantitative manipulations, in which the tightest possible joints must be secured, the eaontchouc connector is bound on to the glass tube witrh a silk or smooth
linen strirg; the string is passed as tightly as possible
twice rounmd the connector, and tied wNith a square knot;
the string shoulid be moisteined in order to prevent it fioma
slippingr- while the knot is tying.
Caoutchouc stoppers of good quality are mnuc  more
durable than corks, and are in every respect to be preferred. The German stoppers are of excellent shap1 e and
quality; the American, being chiefly intended for wine
bottles, are apzt to be too conical.  Caoutchouc stoppers
can be bored like corks (see the next section) by means
of suitable cutters, andl glass tubes can be fitted into the
holes thus made with a tightness unattainable with corks.
German stoppers m1acy be boughtL already provideCd with
one, two, and t lee holes. It is not well to lay in a large
stock of caoutchouc stoppers; for, though they last a long
time whlen in constant use, they not infreq-uently deteriorate NA7when kept in store, beconinog  hard aind somewhat
brittle with age. These stoppers must not be confounded
with the very inferior caps whicll were in use a few years
ago.
Pieces of thin sheet caoutchouc are very conveniently
used for mahking tight joints between  large tubes of two
different sizes, or between the neck of a flask, or bottle,
and a large tvbe which enters it, or between the neck of
a retort and the receiver into which it enteLrs. A suficiently broad and lonog piece of sheet cao-utchoula  is considerably stretched, wrapped tightly over the glass parts
adjoining the aperture to be closed, and secured in place
by a string woulnd closely about it ani tied with a square
knot.




~ 177                    corKas.                      179
177.  Co0r,c.. It is often very di'ficult to obtain sound,
elastic corks, of fine grain and of size suitable for large
flasks and wide-mouthed bottles.  On this account, bottles
with mouths not too large to be closed with a cork cuL
across the grain should be chosen for chemical uses in
preference to bottles which require large corks or bungs
cut with the grain, and therefore offering continuous
channels for the passage of gases, or even liquicds.  The
kinds sold as chaampnagne corks and as satin coreks for
phials, are suitable for chemical use.  The best corks generally need to be softened before using; this softening
may be effected by rolling the cork under a board upon
the table, or undcler the foot upon the clean floor, or by
gently squeezing it on all sides with the well-klnown tool
expressly adapted for this purpose, and thence called a
cork-squeezer; steamin' also softens the hardest corks.
Corks must often be cut with cleanness and precision;
a sharp, thin knife, such as shoemakers use, is desirable
for this purpose.  Wihen a cork has been pared dlown to
reduce its diameter, a flat file may be employed in finishing; the file must be fine enough to leave a snmooth surf ace
upon the cork; in filing a cork, a cylindrical, rather than
a conical, form should be aimed at.
In boring holes through corks to receive glass tubes, a
hollow cylinder of sheet brass sharpened at one end is a
very convenient tool.  Fig. 24 represents a set of such
little cylinders of graduated sizes, slipping one within
the other into a very compact form; a stout wire, of the
same leng'th as the cylinders, accompanies the set, and
serves a double purposet-passed transversely throu'gh
two holes in the cap which terminates each cylinder, it
gives the hand a better grasp of the tool while penetrating the cork; and when the hole is made, the wire thrust
through ann opening in the top of the cap expels the little




180         PUTTING TUBES THROUGH CORIKS.       ~ 177
cylinder of cork which else would remain in the cutting
cylinder of brass. That cutter, whose diameter is next
below that of the glass tube to be inserted in the cork, is
alwTays to be selected, and if the hole it makes is too
small, a round file must be used to enlarge the aperture;
the round file, also, often comes in
Fig. 24.   play to smooth the rough sides of a
hole made by a dull cork-borer. A
pair of small calipers is a very conveJ~   11        nient, though by no means essential,
d —+ C = l     tool in determining which size of
cutter to employ. A flask which presents sharp or rough edges at the
mouth can seldom be tightly corked,
for the cork cannot be introduced into the neck without being cut or
roughened; such sharp edges must be
rounded in the lamp.  In thrusting
glass tubes throug'h bored corks, the
following directions are to be observed:  (1.) The end of
the tube must not present a sharp edge capable of cutting
the cork.  (2.) The tube should be grasped very close to
the cork, in order to escape cutting the hand which holcds
the cork, should the tube break; by observing this precaution, the chief cause of breakage, viz., irregular
lateral pressure, will be at the same time avoided.  (3.)
A funnel-tube must never be held by the funnel in driving
it through a cork, nor a bent tube grasped at the bend,
unless the bend comes immediately above the cork.  (4.)
If the tube goes very hard through the cork, the application of a little soap and water will facilitate its passage;
but if soap is used, the tube can seldom be withdrawn
from the cork after the latter has become dry.  (5.) The
tube lmust not be pushed straight into the cork, but




~ 178               GAS-BOTTLE.                  181
screwed in, as it were, with a slow rotary as well as onward motion. Joints made with corks should always be
tested before the apparatus is used, by blowing into the
apparatus, andl at the same time stopping up all legitimate
outlets. Any leakage is revealed by the disappearance of
the pressure created. To the same end, air may be
sucked out of an apparatus and its tightness proved by
the permanence of the partial vacuum. To attempt to
use a leaky cork is generally to waste time and labor, and
to insure the failure of the experiment.
178. Gas-bottle. Fig. 25 represents a gas-bottle fitted
for evolving sulphuretted hydrogen, carbonic acid, and
other gases which can be prepared        ig. 25.
without heat. A straight glass tube
the caoutchouc connector at the right
to carry the gas into the solution to
be tested.. The neck of the bottle
should be rather narrow, since it is
difficult to obtain tight stoppers for
bottles with wide mouths, but must
nevertheless be wide enough to admit
a cork, or better a caoutchouc stopper, capable of carrying both the delivery and the thistle tubes.
To prepare, for example, sulphuretted hydrogen gas,
put a tablespoonful of fragments of sulphide of iron in
the bottom of the bottle, replace the cork with its tubes,
and press, or rather twist, it tightly into the neck of the
bottle; pour in enough water through the thistle-tube to
seal the lower end of that tube, and finally as much concentrated sulphuric acid as would be equal to a tenth or
a twelfth of the volume of the water.
9




182          SELF-REGULiTING GENERIATOR.        ~ 179
At the start it is well thus to mix strong acid with the
water in the bottle, for the heat generated by the union
of the two liquids serves to warnm the apparatus, and to
facilitate the decomposition of the sulphide of iron; but
it must be remembered that strong sulphuric acid is by
itself  nufit for generating sulphurettecl  hydrogen, and
that the evolution of gas would be checked if much of it
were added. When the flow of gas ceases, pour a small
portion of dilute su-lphuric acid into the thistle-tube, and
repeat this operation as often as may be necessaxy to
maintain a constant stream  of gas. Dilute acid fit for
this purpose may be prepared by mixing 1 volume of
strong sulphuric acid with 14 volumes of water; the
water should be well stirred and the acid poured into it
in a fine strearm.
In precipitating the members of Classes II and IIl
wvith sulphuretted hydrogen, the gas delivery-tube should
not dip deeper tlan about an inch beneath the surface of
the liquid in the beaker. A rapid current of gas is useless and wasteful. The best method of operating is to
pour dilute sulphuric. acid into the thistle-tube in such
quantity that the bubbles of gas may: follow one another
slowly enough to be counted without effort.
179.  Self-regulating  Gas-yenerator.  An  apparatus
which is always ready to deliver a constant stream of
sulphuretted hydrogen, and yet does not generate the
gas except when it is immediately wanted for use, is a
great convenience in an active laboratory.  The same remark applies to the two gases, hydrogen  and carbonic
acid, which are likewise used in considerable quantities
in quantitative analysis, and which can. be conveniently
generated in precisely the same form of apparatus which
is advantageous for sulphuretted hydrogen..  Such a




179         SEALF-REGULATING GENERATOR.              183
generator may be made of divers dimensions.  The foll-owing directions, with the accomFig. 26.
panying  figure  (Fig. 26), will
enable the student to construct
1an apparatus of convenient size.
Procure a glass cylinder, 20 or
25 c. n. in diameter, and 30 or
35 c. m. high; ribbed candy jars
are sometimes to be had of about
this size; procurle also a sto;ut         2 =
tllbublated bell-glass, 10 or 12 c. m.
wTide, and 5 or 7 c. m. shorter
than the cylinder.  Get a baskset
of sheet-lead, 7.5 c. in. deep, and 
2.5 c. in. narrower than the bellglass, and bore a number of small
holes in the sides and bottomi of this basket.  Cast a
circular plate of lead, 7 in. in. tick, and of a diameter
4 c. In. larger than that of the glass cylinder; on what is
intended for its under side, solder three equidistant
leaden strips, or a continuous ring of lead, to keep the
plate in proper position as a cover for the cylinder.  Fit
tightly to each endl of a good brass gas-cock a piece of
brass  tube 8 c. m. long, 1.5 to 2 c. m. wide, and stout in
metal.  Perf'orate the centre of the leaden plate, so that
one of these tubes will snugly pass through the orifice,
and secure it by solder, leaving 5 c. in. of the tube -projecting' below the plate.  Attach to the lower end of this
tube a stout hook on which to hangt the leaden basket.
By means of a sound cork and common sealing-wax, or a
cement made of oil mixed with red and white lead, fasten
this tube into the tubulature of the bell-glass air-tight,
and so firmly that the joint will bear a weiglht of several
uounds.  Ha1ng  the basket by means of copper wire




184                   MORTARS.                  ~ 180
within the bell, 5 c. m. above the bottom of the latter.
To the tube which extends above the stop-cock attach by
a good cork the neck of a tubulated receiver, of 100 or
150 c. c. capacity, the interior of which has been loosely
stuffed with cotton. Into the second tubulature of the
receiver fit tightly the delivery-tube carrying a caoutchouc
connector; into this connector can be fitted a tube
adapted to convey the gas in any desired direction.
When many persons use the same generator, each person
must bring his own tube.
To charge the apparatus, fill the cylinder with dilute
acid to within 10 or 12 c. m. of the top; fill the basket
with fragments of sulphide of iron; hang the basket in
the bell, and put the bell-glass full of air into its place,
with the stop-cock closed. On opening the cock, the
weight of the acid expels the air from the bell, the acid
comes in contact with the solid in the basket, and a steady
supply of gas is generated until either the acid is saturated or the solid dissolved; if the cock be closed, the
gas accumulates in the bell, and pushes the acid below
the basket, so that all action ceases. In cold weather,
the apparatus must be kept in a warm place. For generating sulphuretted hydrogen, sulpharic acid, diluted
with fourteen parts of water, is used; for hydrogen, zinc
and sulphuric acid, diluted with four or five parts of
water; while for carbonic acid, chalk and muriatic acid,
diluted with two or three parts of water, should be
taken.
180.  iortars.  Whenever the substance to be analyzed occurs in the form of large pieces or coarse powder,
it should, as a general rule, be pulverized by mechanical
means before subjecting it to the action of solvents.
Mortars of iron, steel, agate, or porcelain are used for




~ 180                  MORTARS.                      185
this purpose, accordcing to the chartacter of the substance
to be powdered.
An iron mortar is useful for coarse work, and for effecting the first rough breaking up of substanees which are
subsequently powdered in the agate or porcelain mortar.
If there be any risk of fragments being thrown out of
the mortar, it should be coverel with a cloth or piece of
stiff paper, having a hole in the middle through which
the pestle may be passed.  Instead of the common iron
mnortar, a small steel mortar, of the kind called diamond
mortars by dealers in chemzical ware, may be used for
crushing rminerals.  Pieces of stone, minerals, and lumps
of brittle metals may be safely broklen into fragments
suitable for the mortar by wrapping thenm in strong paper,
laying them so enclosed upon an anvil, and striking them
with a heavy hammuer. The paper envelope retains the
broken particles, which might otherwise fly about in a
dangerous manner, and be lost.
The best porcelain mortars are those known by the name
of Weclgewood-ware, but there are many cheaper substitutes.  Porcelain mortars will not bear sharp and heavy
blows; they are intended rather for grinding or triturating saline substances than for hammering; tflme pestle
may either be formed of one piece of porcelain, or a piece
of porcelain cemented to a wooden handle; the latter is
the less desirable form  of pestle.  UInglazed porcelain
mortars are to be preferred. In selecting mortars, the
following points should be attended to: 1st, the mortar
should not be porous; it ought not to absorb strong acids
or any colored fluid, even if such liquids be allowed to
stand for hours in the mortar  2d, it should be very hard,
and its pestle should be of the same ha'rdness; 3d, it
should be sound; 4th, it should have a lip, for the co'lvenience of pouring out liquids and file powders.  As a




186                   SPATUL.                   ~ 181
rule, porcelain mortars will not endure sudden changes
of temperature. They may be cleaned by rubbing in
them a little sand soaked in nitric or sulphuric acid, or,
if acids are not appropriate, in caustic soda.
Agate mortars are only intended for trituration; a blow
would break them. They are exceedingly hard and impermeable. The material is so precious and so hard to
work, that agate mortars are always small. The pestles
are generally inconveniently short, a difficulty which may
be remedied by fitting the agate pestle into a wooden
handle.
In all grinding operations in mortars, whether of porcelain or agate, it is expedient to put only a small quantity of the substance to be powdered into the mortar at
once. The operation of powdering will be facilitated by
sifting the matter as fast as it is powdered, returning to
the mortar the particles which are too large to pass
through the sieve.
181. Spatulce. For transferring substances in powder,
or in small grains or crystals, from one vessel to another,
spatulh and scoops, made of horn or bone, are convenient
tools. A coarse bone paper-knife makes a good spatula
for laboratory use. Cards, free from glaze and enamel,
are excellent substitutes for spatulae.




INDEX.
ACETATE OF LEAD, as reagent, 142.    Arsenic acid, tests for, 87.
Acetates, tests for, 97.                 Arsenious acid, how  distinguished
Acid solutions, 110, 114.                              from arsenic acid, 88.
Alkaline solutions, 110.                             as a sublimate, 103.
Aluminates, precipitated with Class                  tests for, 87.
IV, 46.                              Arsenites, tests for, 87.
Aluminum, confirmatory test for, 50.  Ash of charcoal, 106.
a member of Class IV,
20, 45.                   BARIUM, a member of Class VI, 22, d1.
precipitated as hydrate,             precipitated as carbonate, 22,
20, 50.                              61.
presence of indicated, 53.           precipitated as chromate, 62.
Ammonia-water, as reagent, 136.                  salts soluble in ammoniacal
Ammonium  salts, testing for, 103,                 solutions, 77.
131.                        Barium-test for certain  classes  of
Antimony, confirmatory test for, 42.                salts, 75.
converted into an insolu-   Beakers, 150.
ble oxide by  11NO3,   Biborate of sodium, as reagent, 139.
128.                      Bichloride of platinum, as reagent,
see sulphide of.                   how prepared, 143.
globule, brittle, 106.      Bismuth, confirmatory test for, 32.
a memlber of Class III, 19,          globule, brittle, 106.
39.                                a member of Class II, 19, 29.
oxide  of, dissolved  by             precipitated as hydrate, 32.
tartaric acid, 42.                      "        " sulphide, 19.
precipitated as sulphide,               30.
19, 38, 42.                        presence of indicated, 37.
presence of indicated, 41,   Blast-lamps, 156.
45.                       Blowers, 156.
teroxide of, as a subli-   Blowing bulbs, 171.
mate, 103.                Blowpipe, 163.
Aqua-regia, how prepared, 134.                   how to use, 164.
its use as a solvent, 114.           lamp, 163.
Arseniates, test for, 87.                Boracic acid, precipitated from  an
Arsenic, confirmatory tests for, 40, 43.            alkaline solution, 111.
a member of Class III,                tests for, 91.
19, 39.                   Borates, tests for, 91.
presence of indicated, 36,  Borax-bead, how to dilute, 120.
45.                v                           make, 119.
see snlphide of.            Bottles, how to handle, 147.
separation as sulphide,19,   Bromides, tests for, 79, 94.
38.                       Bromine, tests for, 94.
as a sublimate, 103.        Bunsen's burner, 155.




188                                INDEX.
CADMIUM1, a member of Class II, 19,  Chromium gives a green borax-beads
29.                                     119.
precipitated as sulphide, 19,           precipitated as hydrate, 20,
29.                                     45.
presence of indicated, 36.              presence of indicated, 53.
Cadmium, separation of, 33.             Class, term defined, 14.
Calcium, a memlber of Class VI, 22, 61.  Class I, defined, 15.
precipitated as carbonate, 22,          how to precipitate, 26.
61.                          Class I, defined, 19.
precipitated as oxalate, 63.            how to precipitate, 29.
Calcium-test, for certain classes of  Class III, defined, 19,
salts, 78.                            how to dissolve the sulphides
Caoutchouc stoppers, 178.                          in NalS, 38.
tubing, 177.                   Class IIT, precipitation of, 38.
Carbonate of ammonium, as reagent,  Class IV, defined, 20.
137.                                      how  to precipitate, 46, 52,
Carbonate of sodium, as reagent, how               53.
purified, 138.                            salts precipitated with, 45.
Carbonates, test for, 84.                        treatment  of with  oxalic
Carbonic acid, tests for, 84.                      acid, 47.
Caustic soda solution, how prepared   Class V, defined, 21,
and kept, 137.                            how to precipitate, 54, 60.
Charcoal for blow-pipe use, 104.        Class VI, defined, 22.
Chlorates, tests for, 96.                        how to precipitate, 61, 64.
Chloride of ammionium, as reagent,  Class VII, defined, 22.
137.                                  how isolated, 22, 70.
uses of, 21, 53, 65.           Clay chimney for Bunsen's burner,
Chloride of barium as reagent, 142.            160.
Chloride of calcium, as reagent, how   Closed-tube test, 100.
prepared, 141.                    Cobalt, a member of Class V, 21, 559
Chloride of lead, solubility of, 27.             blowpipe test for, 57.
Chloride of mercury, as reagent, 143.            confirmatory test for, 59.
Chloride of silver soluble in amluionia-         precipitated as sulphide, 21,
water, 28..               55.
Chlorides, tests for, 7, 93.                     presence of indicated, 60.
Chlorhydric acid, as reagenlt, 133.     Copper, a mel-mber of Class II, 18, 20.
its application as a solvent,           confirmatory test for, 34.
108.                                  gives blue solutions, 33.
pure, when needed, 66.                  gollule described, 105, 106.
Chlorine, tests for, 79, 93.                     precipitated as sullphide, 19
Chromate of lead, a test for chro-                29.
minum, 49.                            presence of indicated, 37.
Chromate of potassium, as reagent,  Cork-cutters, 180.
139.                         Corks, 179.
Chromates, barium test for, 76.                 to force tubes throufh, 180.
reduction of by II"2S, 37, 87.  Cyanide of mercury, to detect cyanotests for, 87.                            gen in, 85.
Chrome-iron-ore, hard to decompose,  Cyanide of potassium, as reagent,
120, 121, 126.                      140.
Chromic-oxide, hard to decompose,  Cvanides, tests for, 80, 82, 85.
1207  Cyjanogen, tests for, 82, 85.
Chromites, precipitated  with Class
IV, 46.                      DEFLAGCRATION, 125.
Chro.ium, a  member of Class IV,  Diphosphate of sodiunm, as reagent,
20 45.                            13).
detected as chromate of  Dissolving0 inl acids, 112.
sudimn, 4i8                           in water:, 108.




INDEX.                                189
EFFERVESCENCE, what it indicates,   Iron, to be converted into ferric salt,
83.                                            52.
Elements, identified by compounds,   Iron, a member of Class IV, 20, 45.
10.                                          precipitated as hydrate, 20,
Elements, 34 treated of, 9.                        45.
Etching glass, a test for fluorine, 92.          presence of indicated, 53.
Evaporating test, applied to a liquid,           Prussian-blue test for, 48.
130.                                         reaction in borax bead, 120.
Iron stand, 161.
FErRI- and FERRO-CYANIDES of potassium, as reagents, 140.   LABELLING, importance of, 17.
Filtering, 150.                          Lamps, 155.
Filter-stand, 152.                       Lead, belongs to two classes, 19.
1Flasks, 149.                                    see chloride of.
Fluoride of silicon, a test for fluorine         globule described, 105, 106.
and silicon, 93.             Lead a member of Class I, 15, 27.
Fluorides, tests for, 92.                          "    "   "  II, 19, 29.
Fluorine,'"       92.                         paper, how prepared, 142.
Fluorine, to be sought in an insoluble           precipitated as sulphide, 19,
mineral, 120,                            29.
Folding filters, 151.                            precipitation of as chloride,
Funnels, 150.                                      26.
Fused minerals, how treated, 121.                precipitation of as sulphate,
Fusion with acid sulphate of sodium,                27, 32.
123.                                  presence of indicated, 36.
with CaC03 and NH4C1, 124.              the sulphate changed to chrowith  carbonate of sodium,                 mate, 32.
121.                          Lime-water, as reagent, 141.
Fusions in platinum crucibles, 159.     Liquids to be tested with litmus, 131.
Litmus paper, how prepared, 144.
GAS-BOTTLE, 181.
Gas-generator, self-regulating, 182.   MAGNE;SIUm, as member of Class VII,
General reagent, defined, 15.                      23, 67.
General reagents for acids, 74.         Magnesium, precipitated as phosphate
General reagents, to be used in a cer-             of Mg and (NH i), 23, 67.
tain order, 24.                       separation as oxide, 69.
Glass, bending  and closing tubes,  Manganate of sodium, 49.
171.                         Manganese, confirmatory test for, 56.
cutting and cracking it, 169.           green mianganate  test for,
tubing, 168, 169.                         49;
Gold globule, described, 105, 106.               precipitated with  Class IV,
insoluble in HNO3, 128.                       46.
a member of Class III, 19, 43.             precipitation of, as hydrate,
presence of indicated, 44.                    56.
purple of Cassius test for, 128.            presence of indicated, 60.
Mercurous chloride, reaction with amIIYDROGEN, its presence inferred, 72.              monlia-water, 28.
lHyponitric acid, 102.                  Mercury, belongs to two classes, 19.
HIyposulphites, tests for, 86.                   compounds  as  sublimates,
103.
TNDIGO SOLUTION, how prepared, 144.              a member of Class I, 15, 28.
Insoluble substances, 116.                   "      " "            II, 19, 29.
Iodides, tests for, 95,                          precipitation as subchloride,
Iodine, tests for, 95.                             26.
Iodo-starch paper, 141.,                         presence of indicated, 35.
Iron, discrimination between ferrous             reduction of the metal in a
and ferric salts, 52.                   closed tube, 28.




190                                INDEX.
Mercury, reduction of the metal on   PINCEnRs, 166.
copper, 31.                  Platinum, a member of Class III, 19,
separation as sulphide, 19, 29.           43.
as a sublimate, 103.                    crucibles, 167.
Metallic elements, 7 classes of, 25, 71.         foil, 166.
globules described, 105.                insoluble in HNO0,  123.
globules tested in oxidizing            presenrce of indicated, 44.
flame, 106.                           test for, 129.
Metals, action of HNOs on, 127.                 wire, 166,
used in the arts, 126.          Phosphate of calcium, presence of inMolybdate of amlrmonium, a test for                dicated, 53.
phosphates, 89.              Phosphates, precipitated with  Class
lolybdate of ainmonium, as reagent,                IV, 46.
how prepared, 137.                Phosphates, tests for, 88.
Mortars, 184.                           Phosphoric acid, tests for, 88.
Porcelain crucibles, 153.
NEUrrTRAL SOLUTIONS, 110.                        dishes, 153.
Nickel, blowpipe test for, 57.          Potassium, precipitated as cldoroplaa melmbner of Class V, 21, 54.             tinate, 69.
precipitated as cyanide, 58.           flame-test for, 68.
"      sulphide, 21, 54.            a member of Class VII, 22,
NTickel, presence of indicated, 60.                67.
lNitrate of ammonium, as reagent, 137.  Precipitates  compacted  by  bol ing
Nitrate of barium, as reagent, 142.                and siakltin, 33, 55.
when used, 78.               Preliminary examination of a liquid,
Nitrate of cobalt, as reagent, 143.                130.
Nitrazte of potassium, as reagent, 140.  Preliminary treatment, 99.
Nitrate of silver, as reargent, 141.             of a purel  metal or alloy,
Nitrates, tests for, 95.                           126.
Nitric acid, action on metals, 127.     Protochloride of tin, how to make,
dilute, as reagent, 134.                 143.
howv- expelled, 66.            Prussian blue, a test for iron, 48,
strong, as reagent, 134.        Pulverizing, 185.
tests for, 95.
when  to bie used as a sol-  QUALITATIVE ANALYSIS defined, 9.
vent, 113.
Nitrite of potassiumn, as reagent, how   REAGENT T30TTrES, 14G6.
prepared, 140.                    Reajgents,  33-145.
Non-metallic elements, how detected,  Reducing blowpipe flame, 165.
72.                         RIeduction test, 104.
how  to perform with deliORGAINIC {MATTER, detection of, 100.               cacy, 118.
how destroyed, 101.         Reduction test, to be applied to inOrganic sublstances hinder the pre-                soluble substanles, 117,
cipitation of Class IV, 54.,
Oxalate of ammonium, as reagent,  SALTS1 kinds of considered, 74.
137.                                       soluble in water, 109.
Oxalates converted into carbonates,   Sand-bath, 161.
65.                               Separation of two elements, 13.
tests for, 90.                  Sesquichloride of iron, ho1w to make,
Oxalic acid as a sublimate, 104,                   143.
as reagent, 135.               Silicates, alkaline, decomrposed  by
tests for, 90.                            acids, 92.
Oxide of nmercury, as reagent, 143.              decomposed by chloride of
Oxidizing blowppe flame, 164, 165.                 amnmonium, 92.
Oxygen, how reco-nized, 102.            Silicates, the comlmonest of insoluits presence inferred, 72.                bl substances, 124,




INDEX.                                191
Silicic acid, precipitated from  an a!-   Sulphites, tests for, 83.
kaline solution, 112.        Sulphur, as a sublimate, 103.
Silver, a member of Class I, 15, 26.   Sulphuretted hydrogen, decomposed
globule described, 105, 106.               by oxidizing agents, 36.
precipitated   by   reducing            how prepared, 135, 181, 182.
agents, 82.                           how to elmploy it, 29, 35.
precipitation as chloride, 26.          necessity of expelling, 51, 66.
salts, insoluble in dilute ni-  Sulphuretted  hydrogen water, how
tric acid, 80.                          prepared and kept, 135.
salts, sundry colors of, 80.    Sulphuric acid, as reagent, 134, 135.
see chloride of.               Sulphuric acid, tests for, 88.
Silver-t-est. for  certain  classes  of  Snlphurous acid, 102.
salts, 79.                   Sulphur, precipitation of, 30, 37.
Slaked lime, as reagent, 141.           Sulphydrate of ammoninin, as reaSodium, crystallization of chlloropla-             gent, 136.
tinate, 69.                  Sulphydrate of sodium, as reagent,
Sodium,  fiame-test for, 68.                       138.
a mlember of Class VII, 22, 67.
Solvents, the order of use, 108.        Table for Class I, 29.
Spatulh, 186.                                           II, 35.
Special tests for non-metallic ele-                     III, 42.
ments, 83.                                    IV, 51.
Starch paste, how prepared,  144.                        V, 60.
Starch-test for bromine, 94.                             VI, 64.
iodine, 95.                      the separation of the 7 classes
Stirring-rods, 169.                                of metallic elements, 71.
Stoppers, stuck, how to loosen, 147.   Table of the seven classes of metallic
Stroutium, a member of Class VI,                    elements, 25.
22, 61.                      Tartaric acid, as reagent, 135.
precipitated as carbonate, 22,           tests for, 90.
61.                          Tartrates, tests for, 90.
as sulphate, 63.   Test-tsube rack, 149.
Sublimates on cha-rcoal while reducing   Test-tubes, 148.
metals, 106,                 Tin, a member of Class III, 19, 38.
Sulphate of copper, as reagent, 143.             confirmatory test for, 41.
Sulphate of magnesium, as reagent,               converted into an insoluble
how mixed, 142.                          oxide by HINO:, 128.
Sulphate of magnesium, a test for  Tin globule, described, 105, 106.
phosphates and arseniates,            presence of indicated, 36, 41,
88, 89.                               reduction of the  nmetal by
Sulphate of sodium, acid, how  pre-                 zinc, 41.
pared, 139.                   Tin, see sulphide of.
Sulphates, barium  test for, 77.'Triangle, 161.
howN to detect, 88.             Turmeric paper, how to prepare, 144.
insoluble, reduced  to  sulphides, 118.                 UTENSILs, list of, 145.
Sulphate of potassium, as reagent,
lhow prepared, o39.          WATErP, 145.
Sulphide of antimony, oxidation of  Water-bath, 161.
by nitrate of sodium, 41.    WVash-bottle, 167,
Sulphide of arsenic, soluble in car-   Wire-gauze, 161.
bonate of ammoniumn, 39.
Sulphide of tin, oxidation of, by ni-   ZINC, a member of Class V, 21, 54.
trate of sodium, 41.                  precipitated as chromnate, 56,
Sulphides, tests for, 85.                        precipitated as sulphide, 21,
Sulphides of arsenic, as sublimates,                54, 56.
103.                                  presence of indicated, 60.








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"S It is the best work on Drawing that we have ever seen, and isespecially a text-book
of Geometrical Drawing for the use of Mechanics and Schools. No young MIechanic, such
as a Machinist, Engineer, Cabinet-Maker, Millwright or Carpenter, should be without it."
— Scientific American.
" One of the most comprehensive works of the kind ever published, and cannot but
possess great value to builders. The style is at once elegant and substantial. 9' —Pennsylancia Inquirer.
"We think this the best work on this subject, which is saying very much; as much attention has been given to the science of Drawing. There is nothing in the range of drawing that cannot be found in this book, and which is not well explained."-0hio Teacher.' Whatever is said is rendered perfectly intelligible by remarkably well-executed diagrams on steel, leaving nothing for mere vague supposition; and the addition bf an introduction to isometrical drawing, linear perspective, and the projection of shadows, winding
up with a useful index to technical terms."-Glasgow Mechanics' Journal.
t- The British Government has authorized the use of this book in their schools of art
at Somerset House, London, and throughout the Kingdom.
1INIIFIE  (Win.)   Geometrical Drawing.  Abridged from
the Octavo edition, for the use of Schools.   Illustrated
with +8 steel plates.   Fifth  edition, 1 vol. I2mo, half
roan..................................                 1.50
It is well adapted as a text-book of drawing to be used in our High SchooLs and
Academies where this useful branch of the fine arts has been hitherto too much neglected."-Boston Journal.




TD VAgN NOSTRANn'S PUBLICATIONS.
PIERCE (Prof. Benj.) System of Analytical Mechanics.
Physical and Celestial Mechanics, by Benjamin Pierce,
Perkins Professor of Astronomy and Mathematics in
Harvard University, and Consulting Astronomer of the
American Ephemeris and Nautical Almanac. Developed
in four systems of Analytical Mechanics, Celestial Mechanics, Potential Physics, and Analytic Morphology.
i vol. 4to, cloth.oe....... o................... $   o. cio
"I have re-examined the memoirs of the great geometers, and have striven to consolidate their latest researches and their most exalted forms of thought into a consistent and
uniform treatise. If I have hereby succeeded in opening to the students of my country a
readier access to these choice jewels of intellect; if their brilliancy is not impaired in this
attempt to reset them; if, in their own constellation, they illustrate each other, and concentrate a stronger light upon the names of their discoverers; and, still more, if any gem
which I may have presumed to add is not wholly lustreless in the co lection, —I shall feel
that my work has not been in vain."-E'tractfrom the Preface.
PLYDIPTON.  The Blow-Pipe; a System of Instruction in
its Practical Use, being a Graduated Course of Analysis for the Use of Students and all those engaged in the
Examination of Metallic Combinations. Second edition, with an appendix and a copious index. By Geo.
VW. Plympton, of the Polytechnic Institute, Brooklyn.
1 vol. 12mO, cloth.....   o.............o  o     o o e    2.o
P00K   (S. M.)  Method  of Comparing  the  Lines  and
Draughting Vessels Propelled by Sail or Steam. Including  a chapter on Laying  off on  the  Mould-Loft
Floor.   By  Samuel M. Pook, Naval. Constructor.   I
vol. 8vo, with illustrations, cloth.................   5.00
"#Few men have had better opportunity to study the marine architecture of the past
and present than Constructor Pook; and that the theories he has deduced from that study
are correct ones, the fine ships built under his supervision at the government yards bear
witness. The book will be of interest to every shipwright who looks higher than to the
mere swinging of an axe."-Chronicle, Portsmouth, N. I.
ROGERS (H. D.)   Geology of Pennsylvania.  A  complete
Scientific Treatise on the Coal Formations.  By Henry
D. Rogers, Geologist. - 3 vols. 4to, plates and maps.
Boards.........................  30o. o
a




D. VAN NOSTBRAND'S PUBLICATIONS.
RUSSELL  (J. Scott). The Modern System  of Naval Archi~
tecture for Commerce and War,  In Three Parts. Part
x, Naval Design. Part 2, Practical Ship-Building. Part
3, Steam  Navigation. I vol. folio, 27 in. x 20 in., 724
pp. text, and 2 vols. plates, 165 in all, and engraved on
copper, varying in size from folio double elephant, 27
in. x 20 in. to 27 in. x go in., and are drawn to a
practical working scale.  In Portfolio.............. $6o.  00
In  half Russia, 3 volsO.,.................... 105.o00
SHAFFNER  (T. P.)   Telegraph  Manual~.  A  complete
History and  Description  of the  Semaphoric, Electric,
and  Magnetic Telegraphs of Europe, Asia, and Africa,
with 625 illustrations. By Tal. P. Shaffner, of Kentucky.   New  edition.   i vol. 8vo, cloth, 850 pp....   6. 5
SILVERSE   ITH  (Julius).  A  Practical Hand-Book for Miners, Metallurgists, and  Assayers, comprising  the  most
recent improvements in  the disintegration, amalgama
tion, smelting, and parting of the Precious Ores, with a
Comprehensive Digest of the Mining Laws. Greatl.
augumented, revised, and corrected.   By Julius Silversmith.   Fourth  edition.  Profusely illustrated.   x vol.
12Zmo, cloth.......................   0       o........   3. o    00
"'The Practical Hand-Book for Miners, Metallurgists, and Assayers,' by Mr. Julius
Silversmith, a writer well known in connection with mining enterprises, forms a useful
contribution to the scientific literature of the country. It will be found of equal value to
those engaged in mining, either as actual workers, or as owners or shareholders in mialing
property. It gives a brief resume of the geology of metals, quite sufficient for practical
purposes, and evidently gathered from the best authorities. It treats of mining in all its
branches, for ores and native metals, classifying the several kinds of veins and deposits,
and herein exhibits the modes in use in the exploration of mines, tunnels, shafts, adits,
galleries, &c., and the timbering of mines  This part of the book, as indeed most
branches treated, is profusely illustrated by cuts, which must assist the ready comprehension of the matter discussed. A summary of the chemistry and metallurgical treatment of metals follows, and after giving descriptions, accompanied by engravings, of a
large number of the new processes and inventions for treating ores, especially those of tho
precious metals, the book concludes with an exposition of the mining laws of the Pacifle
States and Territories."-New York Herald.
SILVER DISTRICTS OF NEVADA.  8vo, with map,
paper...................................... e o oe                3 




D. VAN NOSTRAND'S PUBLICATIONS.
SIEDBERG. A  Synopsis of British Gas Lighting, comprising the essence of the London 7ournal of Gas Lightiz:g,
from  1849 to 1868.  Arranged and executed by James
R. Smedberg, C. E., Engineer of the  San  Francisco
Gas Works.   Issued only to  subscribers.    4to, cloth.
(Ready soon.)...............................o                    5 oo00
SPBERICAL ASTRONOIIYo. By F, Brunnow, Ph. Dr.
Translated  by  the Author from  the Second  German
edition.   I vol. 8vo, cloth......................   6.50
STILLMlAN  (Paul)o    Steam  Engine Indicator, and the Improved Manometer Steam  and Vacuum  Gauges-their
Utility  and  Application.   By  Paul Stillman.            New
edition.   I vol. I2mo, flexible cloth.............    l.oo
" The purpose of this useful volume is to bring to the notice of the numerous class of
those interested in the building and the use of steam engines, the economy and safety attending the use of the instrument therein described. Tho Manometer has been long used-the
inventor is Watt in a cruder form; and the forms herein described are patented by the
author, The language of the author, the diagrams, and the scientific mode of treatment,
recommend the book to the careful consideration of all who have engines in their care."'
Boston Post.
S3WEET (S. H.)   Special Report on Coal; showing its Distribution, Classification, and cost delivered over different
routes to various points in  the State of New  York, and
the principal cities on  the Atlantic  Coast.  By S. H.
Sweet.  With maps, 1 vol. 8vo, cloth............. 3. 00
ST:EWART (W. M.) The lMineral Resources of the Pacific
States and Territories. By Hon. W. M. Stewart. 8vo,
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WALKER  (W. H.)   Screw  Propulsion.  Notes on Screw
Propulsion, its Rise and  History.   By  Capt. W. H.
Walker, U. S. Navy.   I vol. 8vo, cloth..........                    75
"After thoroughly demonstrating the efficiency of the screw, Mr. Walker proceeds to
point out the various other points to be attended to in order to secure an efficient man-ofwar, and eulogizes throughout the readiness of the British Admiralty to test every novetty calculated to give satisfactory results.      C *   * * Commander Walker's book contains an immlense amount of concise practical data, and every item of information recorded fully proves that the various points bearing ripon it have been well considered
previously to expressing an opinion."-Londonli.ning Journal.




D. VAN NOSTRAND'S PUBLICATIONS.
WARD (J. H.) Steam for the Million. A popular Treatise on Steam  and its Application to the useful Arts, especially to Navigation.  By J. H. Ward, Commander
U. S. Navy.  New  and  revised edition.   a vol. 8vo,
cloth..  o..................  0.......   oo...o  o.......  $ 1. o
WEIBAOC   (Julius).   Principles of the Mechanics of Machinery and Engineering.  By Dr. Julius Weisbach, of
Freiburg.  Translated  from  the last German  edition.
(In press.)...................................
WHILDNB:  (J. K.)  On the Strength of Materials used in
Engineering Construction,  By J. K.'Whilden.   x vol.
2mo cloth   O     D O.................................   2. o3
"We find in this work tables of the tensile strength of timber, metals, stones, wire,
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metals, and stone to crushing; experiments on brick-work; strength of pillars, collapse of
tube; experiments on punching and shearing; the transverse strength of materials; beams
of uniform strength; table of coefficients of timber, stone, and iron; relative strength of
weight in cast-iron, transverse strength of alloys; experiments on wrought and cast-iron
beams; lattice girders, trussed cast-iron girders; deflection of beams; torsional strength
and torsional elasticity."-American Artisan.
WHITNEY  (J. P.)  Colorado, in the  United  States  of
America. Schedule of Ores contributed by sundry
persons to the Paris Universal Exposition of I 867, with
some Information about the Region and its Resourceso
By J. P. Whitney, of Boston, Commissioner from   the
Territory.  Pamphlet 8vo, with maps. London, 1867.                   25
Silver Mining Regions of Colorado, with some account of the different processes now being introduced
for working the Gold Ores of that Territory.  By J. P.
Whitney.      2mo, paper..............,,......               25
WILLIAi  SOA  (R. S.)  On the Use of the Barometer on
Surveys and  Reconnaissances.  Part I. Meteorology in
its connection with HFypsometry.   Part It. Barometric
Hypsometry.  By  R. S. Williamson, Bvt. Lieut-Col.
U. S. A., Major Corps of Engineers.  WVith Illustrative Tables and  Engravings.   Paper No.  i5, Professional. Papers, Corps of Engineers.   1 vol. 4to, cloth. 15. oo
9




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BOEBLING  (J. A.)   Long  and  Short Span  Railway
Bridges.   By John A. Roebling, C. E.  Illustrated
with large copperplate engravings of plans and views.
In press....................................
C LAR.KE  (T. C.)   Description  of the  Iron  Railway
Bridge over the 1Mississippi River, at Quincy, Illinois.   By Thomas Curtis Clarke, Chief Engineer.
Illustrated with  27 lithographed  plans.   I vol. 8vo,
cloth...................................... o   $7.50
TURIER  (P.)   A  Treatise  on  Roll-Turning  for the
manufacture  of Iron.   By Peter Tunner.  Translated and adapted by John B. Pearse, of the Pennsylvania  Steel Works, with  numerous  engravings
and wood-cuts.   Ian press................ 0 0..
IES'.i & WOOi D  (B. F.) Engineering Precedents for Steam
Machinery.  Arranged  in  the most practical and
useful  manner  for  Engineers.   By B. F. Isherwood, Civil Engineer, U. S. Navy.  With  illustrations.  Two volumes in one.   8vo, cloth.........  2.50
EBABUEiR   AN.  Treatise on the Metallurgy of Iron, containing outlines of the History of Iron Manufacture,
methods of Assay, and  analysis of Iron  Ores, processes of manufacture  of Iron and Steel, etc., etc.
By  H. Bauerman.   First American  edition.  Revised and enlarged, with an appendix on the Martin
Process for making Steel, from  the report of Abram
S. Hewitt.  Illustrated with numerous wood engravings.  I2mo, cloth..........................   2. 50
"This is an important addition to the stock of technical works published in this
country. It embodies the latest facts, discoveries, and processes connected with the
manufacture of iron and steel, and should be in the hands of every person interested in
the subject, as well as in all technical and scientific libraries."-Scientiftc Anzerican.
rEPET.  Manual of Inorganic  Chemistry  for Students.
By the late Dudley Peet, M. D.  Revised and  enlarged by Isaac Lewis Peet, A. M.     8imo, cloth...            75
10




1. VAN NOSTRAND S PUBLICATIONS.
BUCG-ET.  Treatise on Optics: or, Light and Sight, theoretically and practically treated; with the application to Fine Art and Industrial Pursuits.  By E.
Nugent.  With one hundred and three illustrations.
211102M     cloth.................  OO............... $2.00
" This book is of a practical rather than a theoretical kind, and is designed to afford
accurate and complete information to all interested in applications of the science.-.lound
Table.
BITUANOW.  Spherical Astronomy.  By F. Braunnow,
Ph. Dr.  Translated by the Author from the Second
German edition.  I vol., 8vo, cloth.............  6. 50
GLYNI7q (J.)  Treatise on the Power of Water, as applied
to drive Flour Mills, and to give motion to Turbines and other Hydrostatic Engines.  By Joseph
Glynn.  Third edition, revised and enlarged, with
numerous illustrations.  x2mo, cloth............ 1.25
ZRI'E.T TREATISE ON OILE DEPO3ITS.  By Bernhard Von Cotta.  Translated from  the Second German edition by Frederick Prime, Jr., Mining Engineer, and revised by the Author.  With numerous
illustrations.  I press.................... 
HUM BER.      A Handy Book for the Calculation of Strains
in Girders and similar Structures, and their Strength,
consisting of FormulSe and corresponding Diagrams,
with numerous details for practical application.  By
William HIumber.   i2mo, fully illustrated, clothh..   2.50
GILLM ORE.  Engineer and Artillery Operations against
Charleston, 1863.   By Major-General Q. A. Gillmore.   With 76 lithographic plates.  8vo, cloth... io.oo
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D. VAN NOSTRAND'S PUBLICATIONS,
MEILITARY AND POLITICAL LIFE OF THE ETlPEROR NAAPOLEON. By Baron de Jomini, General-inChief and Aid-de-Camp to the Emperor of Russia.
Translated from  the French, with Notes by H. W.
Halleck, LL. D., Major-General U. S. Army. 4 vols.
royal 8vo, with an Atlas of 6o IMaps and Plans,
cloth...................................... $2 5. oo
Half calf or morocco...................... 35.oo
Half russia..................... 37. 50
TREATISE ON GRAN D HILITARY OPERATIONS.
Illustrated by a Critical and Military History of the
Wars of Frederick the Great. With a Summary of
the most important principles of the Art of War. By
Baron de Jomini.  Illustrated by Maps and Plans.
Translated from the French By Col. S. B. Holabird,
A. D. C., U. S. Army.  In 2 vols. 8vo, and Atlas,
cloth....................................oo.  I 5    oo
Half calf or half morocco................  I oo00
Half russia..0.......................   2 2.50
CAVALRY: ITS HISTORY, IA iAGEA             I ENT, AND
USES IN WAR..  By J. Roemer, LL. D., late an
Officer of Cavalry in the Service of the Netherlands.
Elegantly illustrated, with 12 7 fine wood engravings.
In one large octavo volume, beautifully printed on
tinted paper.  Cloth..........................  6.00oo
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ELEMi ENTS OF  MIILITARY  ART AND  HISTORY.
By Edward de la Barre Duparcq, Chef de Bataillon
of Engineers in the Army of France, and Professor
of the Military Art in the Imperial School of St. Cyr.
Translated by Brigadier-General George W. Cullum,
U. S. A., Chief of the Staff of BMajor-General H. WV.
Halleck, General-in-Chief U. S. Army. I vol. 8vo,
cloth......................................  5.oo
12