PRACTICAL CHEMISTRY.








^utnawn's (Iemetutyrj ^iem'i B       uid
PRACTICAL CHEMISTRY
FOR USE IN
SCIENCE CLASSES AND HIGHER AND MIDDLE
CLASS SCHOOLS
BY
J. HOWARD
HEAD MASTER OF THE ISLINGTON SCHOOL OF SCIENCE AND ART
NEW YORK
G. P. PUTNAM'S SONS
FOURTH AVENUE AND TWENTY-THIRD STREET
1873








CONTENTS.
PAGE
PREFACE,.......    7
HINTS TO STUDENTS,.....      9
CHAPTER I.
Matter and Force-Simple and Compound Matter -Nature
of Forces-Chemical Force or Affinity-Chemical
Action-Chemical Combination and Mechanical Mixture,.                                      13
CHAPTER II.
Weights and Measures-English and Metric Systems-Calculations-Examples,....   19
CHAPTER III.
Apparatus and Preliminary Operations-Glass-workingLamps-The Blow-pipe and its Use-SupportsPneumatic Troughs and Experiments at same-Mercury Trough, &c.,....26
CHAPTER IV.
Operations Continued - Solution-Evaporation-Crystallisation-Filters anid Filtration-Distillation-Sub.
limation,......   36
CHAPTER V.
Action of the Alkali Metals upon Water, Hydrochloric
Acid, and Ammonia,.               43
CHAPTER VI.
Decomposition of Water, Hyd lochloric Acid, and Ammonia,
by the Electric Cull ent-Constituents of these
Liquids-Analysis al.i Synthesis-Elements and
Compounds-Chlorous and Basylous Elements,.  48




6               CONTENTS.
CHAPTER VII.          rPAE
Combination by Volume and Weight-Table of the Elements-Atomicity of the Elements-Compound Radicals-Chemical Nomenclature-Acids, Bases, and
Salts-Chemical Equations,...56
CHAPTER VIII.
Hydrogen,..  65
CHAPTER IX.
Chlorine,.......  73
CHAPTER X.
Hydrochloric Acid,...         79
CHAPTER XI.
Oxygeni-Oxides-Ozone,.....84
CHAPTER XII.
Water and Hydroxyl,.....93
CHAPTER XIII.
Compounds of Chlorine with Oxygen and Hydroxyl,, 100
CHATER XIV.
Boron-Boric Acids-Borax,.... 105
CHAPTER XV.
carbon and its Compounds with Oxygen,... 107
CHAPTER XVI.
Nitrogen - The Atmosphere - Combustion - Flame —The
Blow-pipe,......  113
CHAPTER XVII.
Oxides and Oxy-Acids of Nitrogen,... 118
CHAPTER XVIII.
Ammonia and Ammonic Salts,.          123
CHAPTER XIX.
Sulphur and Sulphides-Sulphuretted Hydrogen,. 125
CHAPTER XX.
Compounds of Sulphur with Oxygen and Hydroxyl-Modes
of Chemical Action,..... 129
LIST OF APPARATUS,.....135




PREFACE.
THE present work has been prepared to supply the want
-frequently felt by many Teachers and Students of
Chemistry, preparing for the examinations of the Science
and Art department-of a method, by which the subject
could be studied, so as to get a sound knowledge of the
elementary facts of the science.
The reports of the eminent men who act as examiners
for the Science and Art department have shown, that
many students who come up for examination are mere
readers, and they rightly decry such a system of cram,
which can only produce nausea instead of that deep interest in the phenomena surrounding us, which would be
produced if science were really studied practically. These
views the author fully appreciates. He has for some
years taught large classes of young men and boys who
have been successful at these examinations, and feels
assured that Chemistry cannot be understood unless
EXPERIMENT go hand-in-hand with Theory-in fact, that
Theory should be built up by the aid of inferences drawn
from the experiments themselves.
In addition to this, the Department have offered to
assist the individual study of Chemistry by Grants to
the Committees towards the expenses of students in a
laboratory, and also in extra payments to the teacher.
These grants, however, can only be obtained by the
student showing at the examinations a good knowledge




8                    PREFACE.
of Practical Chemistry, and it is believed there is very
little chance of getting a first clss without it.
The teacher, and, if possible, every student, should
perform all the experiments described in the book. It
will be found to contain all that are suggested in the
revised syllabus of the subject for the First or Elementary stage, and many others besides.
The author is indebted to the series of Lectures delivered from time to time by Dr Frankland, and also to
his "Lecture Notes on Inorganic Chemistry," for the
method of treating the subject, and for many of the
explanations of Chemical phenomena given throughout
the work. To this work, and to the work on Inorganic
Chemistry in the present series, the author would refer
the reader for further information on the theoretical part
of the subject.
The illustrations in the book are principally from
photographs of the actual apparatus used, kindly taken
by an old pupil. A few from drawings by another friend.
J. HOWARD.
ISLINGTON SCHOOL OF SCIENCE AND ART,
October 1872.




HINTS TO STUDENTS.
CLEANLINESS is of the utmost importance. Never put
away anything dirty. It takes twice the time to cleanse
glass vessels when chemicals have dried on, that it does
if washed directly they are done with. Many a young
student has thrown away bits of dirty apparatus, which
he would have looked upon with pride, had he polished
them before putting them away.
Do everything and arrange everything in order. Never
be in a hurry or flurry. Serious accidents may occur at
times through not keeping cool. Have a place for everything, and put everything in its place. Put all materials
and apparatus to be used on your left hand before commencing, and move them to your right when you have
done with them, keeping the middle of your table or
bench clear for operating or fitting up. Some arrangement of this kind is absolutely necessary.
Do not be wasteful of your materials, although some
of them may be cheap. Pure, and therefore expensive,
niterials will have to be used in the ADVANCED COURSE,
and occasionally in the present, and the habit of carefulness in all things cannot be too soon acquired. Bad
habits, too, are easily contracted, and are difficult to get
rid of, hence as few as possible should be acquired.
Look over all preparations required for an experiment
before you begin to operate, otherwise you may find the
want of something when it is impossible to get it; or




10             HINTS TO STUDENTS.
you may suddenly discover that you want another hand.
It is a good plan, especially for a teacher, to make a list
of all apparatus and materials required for the series of
experiments which are to engage the attention. Satisfy
yourself beforehand WHY you do everything, and never
be content with making a thing merely do, if it is not
done properly.  Badly fitted corks, requiring lutes or
sealing-wax to stop the leaks must not be suffered at any
time-another should be fitted. Many a serious explosion has occurred for want of these precautions.
In all cases, use the simplest form of apparatus for an
experiment. Unnecessary complications are confusing
both to teacher and student.
Take careful notes of all experiments as they proceed,
on paper, or in a rough note-book. Dr Hofmann used
to say, " The scrap of paper well stained with acid is of
much greater value than the half-worked-out, though
clean notes, written down after the experiment has
passed away." The rough notes should be reproduced
in a more finished form in a book kept solely for that
purpose.  The mere copying of scientific facts and
formulae, previously learned in a practical way, is a great
help towards remembering them.
Chemical operations should be carried on, if possible,
in a room set apart for the purpose. It is better to have
it on the ground floor, if possible, as water is more easily
laid on, and waste carried off by drains. It must be
well ventilated, with a flue in which there is a fire burning, or furnished with a ring of gas-jets, to produce an
ascending current. The flue may be furnished with a
hood, under which experiments may be performed where
noxious vapours arise. A series of zinc tubes, about 21
inches diameter, arranged over the benches, about a foot
from the ceiling, with inverted funnel tubes over the gas
lights leading into them, can be arranged to produce an
upward current, and will keep the room clear. These
may be carried into the flue or out-of-doors.
A chamber about 2 feet by 1- feet, with glass doors,




HINTS TO STUDENTS.              11
should be fitted up in every laboratory, however humble,
in connection with the flue, in which experiments with
chlorine and sulphuretted hydrogen can be carried on.
This, however, can be made to lead out of doors also, by
having a Bunsen constantly burning-the waste heat
being used for a sand-bath in which evaporations may
be carried on, if the chamber be divided by a partition.
The principal sink may be either in the laboratory, or
just outside, and should be of glazed stoneware to resist
acids. They cost about seven-and-sixpence, and may be
had of Doulton, Lambeth. Smaller leaden or japanned
iron basins may be let into the benches to carry off
waste.
The room must be furnished with working-benches,
2 feet 6 inches broad, round the walls, and, if necessary,
down the centre. Each student should be allowed 3 feet
6 inches working space, and a nozzle with a stop-cock
should be connected with the gas pipe, for attaching the
flexible tube. Narrow shelves should be fixed along the
walls, over the benches, to hold the bottles containing materials and reagents. Cupboards or shelves may
be put under the benches, and drawers fitted, to hold
the various kinds of apparatus for general use. Each
student should keep his own apparatus in a box, which
should therefore. be large enough to hold all, except such
articles that are not liable to be broken if left out. The
box may be kept under the bench.
Where a room cannot be set apart for the purpose, flat
tables may be laid across the desks in a schoolroom, and
bottles, etc., kept in a cabinet or cupboard. A fire should,
however, be always burning, so that any unpleasant
fumes can be taken to the flue. Water must be at hand
in a trough that can be emptied, or in pails.
Of course, where a regular laboratory can be fitted up,
further and better means can be adopted than are here
suggested; but such arrangements as these will enable
a large amount of work to be done with not over-fastidious students. The cost of such an arrangement. for




12              HINTS TO STUDENTS.
fittings, including gas and drainage, would be about ~1
per' student. The apparatus for general use, such as
pneumatic troughs, dessicating bottles, supports, Herepath's blow-pipes, etc., with the bottles for materials,
would cost from 5s. to 10s. per student extra-each
student being also furnished with such apparatus as recommended in " the Department list."




PRACTICAL CHEMISTRY.
CHAPTER I.
MATTER AND FORCE-SIMPLE AND COMPOUND MATTER-NATURE
OF FORCES - CHEMICAL FORCE OR AFFINITY- CHEMICAL
ACTION-CHEMICAL COMBINATIONAND MECHANICAL MIXTURE.
1. THE Earth, with the animals and plants upon it, consists of a variety of substances to which the term Matter
has been applied. Matter is that which has weight.
Thus it may be proved by a simple experiment with the
air-pump, that air and other gases have weight, and are
therefore matter, although invisible. Matter consists of
minute particles, or molecules (little masses, from dim. of
L. moles, a mass), a term used now to express the smallest portion of a substance that can exist in a separate
state. These molecules are further supposed by the
Chemist to consist of groups of atoms (from Gr. atomosa, not, and temno, to cut), which are indivisible, and
which cannot exist in a separate state.
2. Matter is either Simple or Compound. Substances
that cannot be separated by any known means into two
or more simpler forms of matter, are called Elements or
simple substances. These elements combine together in
certain definite proportions, by weight and volume, to
form Compounds. There are about 62 known elements,
of which about 40 are well known, the rest being chemi



14               PRACTICAL CHEMISTRY.
cal rarities; but there are an infinite number of compounds.
This Matter, whether organic or inorganic, is con —
stantly in motion, either as a whole, or within itself
among its molecules; being subject to certain Forces or
physical agents.   Some of these forces are constantly
acting; others are only brought into play under certain
conditions; and, lastly, one form of force is frequently
convertible into another-as, mechanical force into heat;
heat, if sufficiently intense, into light; mechanical force
and heat into Electricity; Electricity into Magnetism,
and so on.
Each force has its own special characteristics; but it
will only be necessary to mention here those which bear
upon the subject of the present treatise. Thus, if a
stone be let fall, it comes to the earth, and if not resisted,
would reach its centre.   The force which thus pulls it
towards the centre of the earth is an attractive force,
called Gravitation. It is the attraction of mass for mass,
and acts at immense distances, keeping the earth and
other planets in their orbits round the Sun, as well as
causing water to rush over a precipitous rock and form a
roaring cataract, and enabling us to stand firmly upon
the ground.
Experiment 1. Take a piece of ice, its mass is affected bygravity;
its particles are held together by an attractive force called Oohesion. Pound some of it in a mortar, the cohesive force is
loosened by the mechanical force exerted. Put some into a clean
Florence flask, supported on a ring-stand or tripod, and apply
heat by means of a spirit-lamp or Bunsen's burner. The solid ice
melts. The cohesive force being further overcome by the repulsive force of Heat-the molecules being driven farther asunder,
and liquid water being the result. In a short time the water
is converted into steam, which is invisible in the flask, but on
passing out into the colder air, is converted again into watery
vapour-or condenses-as we often see just above the chimney of
a locomotive, or a little way from the spout of a tea-kettle.
3. Cohesion binds the particles of bodies together, Heat
drives them  asunder.   When the cohesive force predominates, we have a solid; when the forces are equal, we




MATTER AND FORCE.                   15
have a liquid; and when heat predominates, we have a
vapour, or gas.
The properties of the ice in the above experiment,
however, remain unaltered; it may be made to assume
these three states over and over again.
Exp. 2. Take a bit of platinum wire about 5 inches long, heat
it in the Bunsen's flame, it becomes red-hot; but on cooling, it
is found to be unchanged.
Exp. 3. Put the wire, or a small fragment, into a test-tube, and
pour upon it some nitro-hydrochloric acid (aqua regia), made by
mixing hydrochloric acid with a few drops of nitric acid, the
platinum dissolves, and a pungent smelling gas is evolved. New
bodies with totally different properties being produced.
The solution, consisting of platinic chloride, may be put into a
small stoppered bottle for future use.
Exp. 4. Heat a piece of magnesium wire or ribbon in the same
manner as the platinum, it burns with a dazzling white light,
and continues to do so when once ignited, giving off a curling
wreath of white smoke, and leaving behind a crumbling white
substance, called oxide of mragnesiumn (the calcined magnesia of
the druggist), totally different in its appearance from the metal.
If the wire be heated in a porcelain crucible, and care be taken
to avoid loss, the resulting compound will be found to weigh
more than the metal. The increase in weight being due to the
oxygen of the air with which it has combined.
The metal is largely used in pyrotechnic displays, and a lamp
has been constructed to burn it for photographic purposes.
4 The Chemical force, or affinity, as it is sometimes
called, has certain special characters of its own, which distinguish its mode of action from that of other forces. Thus:
a. It only acts at inappreciable distances, requiring
bodies to be in actual contact.
Ezp. 5. Rub a glass rod with a piece of silk, or a stick of sealing-wax on the coat-sleeve. Bring it within a few inches of a
suspended lath or a few scraps of blotting paper-attraction takes
place. The electric force thus produced is capable of acting at
distances that can be measured. Not so chemical force.
Exp. 6. Pound some loaf-sugar, and also some potassic chlorate
(Chlorate of Potash); mix them together on a plate, and bring a
glass rod, moistened with strong sulphuric acid, near the mixture
-no effect is produced; but the mixture inflames directly the rod
is brought into actual contact with it. Note the violet flame and
the black mass of carbon left on the plate.




16              PRACTICAL CHEMISTRY.
To bring bodies into actual contact, it is often necessary to resort to solution, fusion, or conversion into the
state of vapour or gas, so.that a certain amount of mobility may be produced among the molecules. Thus we
have two principal methods, the wet and the dry way.
It is not necessary, however, that both substances should
be dissolved or fused-one of them being so is often sufficient.  A solid should be used in small pieces, or in the
state of powder.
Exp. 7. Pour vinegar upon some pieces of chalk in a beaker or
test-tube, a violent effervescence takes place, and a gas is given off
which extinguishes a flaming match.
Ginger-beer and Seidlitz powders, Sherbet, etc., effervescing when water is poured upon them, are instances
of mixtures of two different substances, which do not act
upon one another until solution is effected.
Exv. 8.* Put a few small chips of Phosphorus on a plate and
cover them with Iodine, heat is evolved, and the two substances
give off vapours which enter into combination and inflame, violet
vapours of ter-iodide of phosphorus being produced.
b. The Chemical force always produces a change of
properties; it is a transforming force, and takes place
most energetically between bodies having opposite properties. Numerous instances have already been given,
and the student will constantly observe the phenomena.
c. The Chemical force always acts on definite quantities of different kinds of matter. Thus, when oxygen
combines with hydrogen to form water, 16 grammes,
ounces, or pounds of the former always combine with 2
grammes, ounces, or pounds of the latter to form 18
grammes, ounces, or pounds. The absolute weight of
a body never being altered by this or any otherforce.
Now, it is the province of Chemistry to investigate the
properties of bodies and the changes they undergo when
brought in contact with one another.    This involves
* Phosphorus is highly inflammable, burning at all temperatures
above the freezing point. It must always be kept in, and cut
under water.




MATTER AND FORCE.                 17
Experiment, Observation, Inference; and hence the term
Practical or Experimental Chemistry.
5. Chemical action. The instances already given of the
action of the chemical force, or affinity, show that it
exerts itself in various ways; but the modes of action
will be better understood at a later period.
Some of the differences between mere mechanical mixture and chemical combination will be now alluded to.
Iron, when left exposed to moist air, rusts, a reddishbrown powder being the result, which contains both iron
and oxygen, the latter being obtained from the air.
Zinc, copper, lead, and magnesium also become tarnished;
and the metals potassium and sodium become covered
immediately with a white crust-in all cases definite
compounds being formed, containing a certain weight of
metal in combination with a definite weight of the oxygen of the air.
Heat generally.assists chemical combination.  Thus,
if mercury be kept for several hours near its boiling
point (360~C), in contact with air, it becomes covered with
an orange-coloured film of mercuric oxide, the oxygen of
the air combining with the metal under these circumstances, in the proportion of 16 to 200 by weight, the product
being the sum of the two, as in all other cases. Without heat, the metal would have been unaffected, whilst
the metals platinum and gold, being unaltered by heat,
are called noble metals.
Exp. 9. Bring a red-hot poker, or iron wire, within a few inches
of a small piece of phosphorus, put on a plate, the phosphorus
inflames, and white fumes are given off.
Exp. 10. Mix together some iron filings and powdered sulphur,
this may be done in any proportions-but is only a mixture,
not a chemical compound.
Draw a magnet through the mixture, or shake some of it over
one-the iron filings separate, and the sulphur is left.
Put some of the mixture into a small Cornish crucible, and put
it in the fire, the sulphur melts and the iron combines with it in
certain proportions. Thus, 56 grammes or grains of iron in this
way always combine with 32 grammes or grains of sulphur to form
ferrous sulphide (sulphide of iron). This sulphide of iron is not
B




18               PRACTICAL CHEMISTRY.
attracted by the magnet, and differs in appearance and properties
from both the iron and the sulphur.
Gunpowder is a good instance of a mechanical mixture
-consisting of charcoal, sulphur, and nitre (potassic
nitrate). The nitre may be dissolved out by water, and
the sulphur afterwards by carbonic disulphide (bisulphide
of carbon), the carbon being insoluble. When the powder
is fired, an immense volume of white smoke is produced,
a variety of new compounds being formed-some solid,
others gaseous, and all totally differing in appearance
from the gunpowder itself.
Mixtures may be made in any proportions, but "a
chemical compound always contains the same elements
in the same proportions, however or wherever obtained."
6. Chemical action generally produces a change of temperature.
Exp. 11. Pour some strong nitric acid on zinc in a test-tube,
violent chemical action takes place, the acid is decomposed, giving
off ruddy fumes, and the test-tube becomes too hot for the hand to
bear.
Exp. 12. Put some crystals of sodic sulphate (Glauber's salts)
into a beaker, and add some common hydrochloric acid to them.
If the bulb of a thermometer be plunged into the mixture, the
temperature will be found to suddenly fall. The water locked
up in the crystals like ice being converted into a liquid, abstracts
heat from everything around it.
7. Chemical action generally produces a change of state.
Liquids and gases being converted into solids, or vice
versd.
Exp. 13. Dissolve some baric chloride in a test-tube, and some
sulphuric acid, a white solid separates, or is precipitated.
Exp. 14. Dip a glass rod into hydrochloric acid, and hold it
over an open bottle containing a solution of ammonia, white fumes
are produced, which if in sufficient quantity would produce the
solid ammonio chloride (sal ammoniac).
8. Chemical action often produces a change in colour.
Exp. 15.. Add a solution of potassic iodide to a solution of mercuric chloride (corrosive sublimate), both colourless liquids, a
splendid scarlet precipitate of mercuric iodide will separate.
If potassic iodide be added in excess the precipitate dissolves.




WEIGHTS AND MEASURES.            19
CHAPTER II.
WEIGHTS AND MEASURES.
9. MENTION has been made several times in the previous
chapter of weight and volume. It will be well therefore
before entering on the systematic study of our subject,
that the student should know something about the
weights and measures used in chemical investigations and
calculations.
In England, up to the present time, it has been usual
to speak of pounds, ounces, and grains in weight; of
yards, feet, and inches in length; of square yards, feet,
and inches obtained by squaring the dimensions in linear
measure; and of cubic yards, feet, and inches with the
gallon, quart, and pint, as measures of capacity.
Thus our English standard measure of length is the
yard, obtained by taking j- of the length of the pendulum, which beats seconds in the latitude of London
(= 39-13983). Our standard of capacity is the gallon,
which contains 277,274 cubic inches, being thus related
to the cubic foot or yard which contain respectively 1728
and 46,656 cubic inches. The weight of a gallon of
distilled water at 62~ Fahr. (16-6~C) and 30 inches barometrical pressure divided by 10, gives us the pound
avoirdupois, which is our standard of weight. That is,
a gallon of water weighs 10 lbs., or 70,000 grains. Now,
all this is simple enough, but when we come to the
multiples and fractional parts of the standards, we have
an infinite variety, and the getting up the tables of
weights and measures is a most laborious work to the
young. Add to this the fact of there being two recognised pounds. The avoirdupois, divided into 16 ounces,
and 7000 grains; and the Troy pound, divided into 12
ounces, and 5760 grains, by which we see the lb. av. is
heavier than the lb. Troy, whilst the Troy ounce is
heavier than the ounce avoirdupois; an ounce of tin




20             PRACTICAL CHEMISTRY.
being in fact lighter than an ounce of gold, although a
pound of the former metal is considerably heavier than a
pound of the latter.
In addition to this, the gallon and several other
measures and weights differ considerably in different
parts of the country. To obtain something like uniformity would hence be a great gain, and if this
could be done, much might be said against any radical
change.
But the man. who would understand the truths of
science at the present day must go beyond this. A
foreigner makes some important scientific discovery, or
clears up some obscure point for the student and teacher
who is ever learning.  He gives in the course of his
statements weights and measures that it is impossible to
translate into their English equivalents without much
labour, or recourse to tables which may not be at hand.
Hence half the value of the facts is lost for want. of an
easily convertible system.
For the diffusion of scientific knowledge, then, a universal system of weights and measures would be desirable. It has been proposed to adopt the metric system
used by France and many other European nations; and
legislation has gone so far already in this country, as to
allow of its use side by side with the old system. It
is to be taught also in all schools henceforth receiving
Government aid, and is now being taught far and wide.
Being moreover a decimal system, it is easily learnt.
The foundation of this system is the Metre, first
obtained by measuring an arc of the meridian-or, taking
4   1,o ~-0,Y  of the earth's circumference as the unit of
length. On subjecting this arc to further measurement,
the result was found, however, not to be quite the same as
that first obtained, but this does not matter, as the Standard Metre is now defined to be "the length of a bar of
platinum deposited in the archives of Paris," copies of the
same being deposited with the warden of the standards
in this country,




WEIGHTS AND MEASURES.             21
It stands in relation to our English measure as
follows:1 metre = 39 37079 inches,
or nearly 1 yard 3 inches and 3-eighths.
Taking the metre as the standard of length, the French
use the Greek prefixes deka, hecto, kilo, and myria respectively for the multiples 10, 100, 1000, and 10,000.
To mark the fractional parts  --, - -o-o, the Latin
prefixes deci, centi, and milli. It is therefore a decimal
system, and multiplications and divisions are hence performed by "moving the point to the right or left."  See
examples, page 23, first series.
Passing by Square measure as of little interest to the
student of chemistry, we come to Cubic measure, or
measure of capacity or volume.
Taking a cube with a metre for its side, and taking
Y _1   of such a cube; or, what is the same thing, taking
a cube with a decimetre for its side, we have the cubic
decimetre, to which the term Litre has been applied, and
this is the standard measure of volume or capacity.
In relation to our English measure, the
Cubic inches. Pints.
Litre = 61-027051 = 1-76 or about 1- pints.
The litre wine bottle is now quite common in London.
The same prefixes are used for multiples and fractional
parts, as in the measure of length, thus simplifying the
calculations of the system.
Again, taking a cube with T-o of a metre, or a centimetre for its side, we have the cubic centimetre or
millionth part of a cubic metre. The weight of this
quantity of distilled water at its greatest density
(4~ centigrade) is taken as the standard measure of
weight, and is called the gramme (Anglicised, gram).
In relation to our English weights, the
Grains. Avoir. oz. Troy oz.
Gramme = 15-43  -035'032 or nearly 151 grs.
As in the previous cases, we have decagrams, hectograms, kilograms, and myriagrams; decigrams, centi



22               PRACTICAL CHEMISTRY.
grams, and milligrams.   The gram is about ~, —6-,
of an English ton, the kilogram    about 2- lbs.   The
French use the prefix demi, half, in many cases, as demikilogramme, half a kilogram, a little more than an
English pound.
TABLE OF THE METRIC SYSTEM.
Standard: lThe Metre = 1-0936 yards
LINEAR MEASURE.
Metres.
Decimetre, dmi. Y  or 1  of a. Decametre, dkm.    10
pi..  Hectometre, h 100
Centimetre, cm. -,,'01,,                 m Keilometre, km.  100
KC~ilometre,  km.  1,000
Millimetre, mm. mu,, 001,,J    Myriametre, mrm. 10,000
Square measure or area is omitted as unimportant to the
chemical student.
CUBIC MEASURE, MEASURE OF CAPACITY OR VOLUME.
Standard: the Litre or cubic decimetre = 1*76 pints.
Decilitre, dl.  -' or'1  of a  Decalitre, dkl.  10 litres
Centilitre, c.                  Hectolitre, cl.,,  100 
Millilitre, ml. oo1,,'001,, J  Kilolitre, kl. 1,000,,
Note. — Litre of water = 1 kilogram (2-205 lbs.) A c. c. or millilitre of water
1 gram.
WEIGHT.
Standard: the Gramme = 15'43 grains.
Decigram, dgr. -I- or 1 of a  g Decagram, dkgr. 10 grains
Centigram, cgr. -O,,'01,,   Hectogram, hgr.  100,,
Milligram, mgr.   -,' 001,, J  Kilogram, kgr. 1,000
The quintal is 100,000 grammes, and the French ton a million
grammes.
Note.-A grain (70 of a lb. av. or 570 lb. Troy)='0648 of a gram.
1 lb. avoirdupois ='4536 of a kilogram (about Ilbs.).
Examples of Calculations.  N.B.-To multiply by 10,
100, 1000, etc., move the decimal point one, two, or
three places to the right, adding ciphers if necessary.
Thus 6-75-67-5, 675, 6750.
To divide by 10, 100, 1000, move the decimal point
one, two, or three places to the left, prefixing ciphers if




WEIGHTS AND MEASURES.                  23
necessary.    Thus    759-6876 -   75-96876,    7-596876,
*0759687, etc.
SERIES I.
1. How many metres in 50 kilometres?
Here 50 x 1000 = 50,000 or 50', move point 3 places to
the right, and add three ciphers = 50000 kilom.
2. How many litres in 62-54 kilolitres?
Here 62'54 x 1000 = 62540' litres.  One cipher being
required.
3. How many milligrams in 576 596 decagrams?
Here 576-596 x 10,000, or move point 4 places to right,
requiring one cipher to be added = 5765960' dekagrams.
4. How many kilolitres in 5765960 litres?
Here, fewer being required, 5765960. 1000, or move the
point which falls on the right of the unit 3 places to
the left. Ans. 5765'96 kilolitres.
5. How many decagrams in 7'6467 centigrams?
Here 7'6467   1000, or move the point 3 places to the
left, and as only 1 figure now stands to the left, add 2
ciphers ='0076467 centigrams.
6. How many cubic decimetres in 54786 decilitres?
Here mark the relation of length cubed to capacity. The
cubic decimetre or decimetre cubed, is called a litre.
Hence 54786 - 10 = 5478-6 cubic decimetre or litres.
7. Add together 657-6mm, 760mm, 5.8m, 760cm, 58dkm,
39dcm, and subtract from the result, 64-5 metres.  -6576
Here, put down all in terms of a metre, thus:-  7600
5 8000
7-6000
580 0000
3 9000
598-7176
64'5000
534'2176
As it will be necessary for the student to know how
to compare the weights of a given volume of different
gases, the plan of Dr Hofmann, adopted by Dr Frankland, will be given here, with some calculations to illustrate it.
The weight of a litre of hydrogen gas at the standard
temperature and pressure, i.e., 0~c and 760mm Bar., is




24                PRACTICAL CHEMISTRY.
*0896 of a gram. This Dr Hofmann called the crith,
and the weight of an equal volume of any other gas at
the same temperature and pressure is found by multiplying this by the specific gravity of the gas compared with
hydrogen as unity, the answer being given in criths, or
absolutely by taking so many times *0896 gr.
Thus, oxygen being 16, nitrogen 14, chlorine 35-5 (351),
and air, 14'47 (141 nearly), times the weight of hydrogen; the weight of a litre of any of these gases would be
so many criths, or -0896 x 16, 14, 35-5, and 14'47; or,
1-4336, 1*2544, 3-1808, and 1-296512 grams respectively.
SERIES II.
Examples.
Question 1. A litre of air weighs (at 0~c and 760mm Bar.) 1 2965
grammes. What is the volume occupied by 1 kilogram?
1000
Here-   --- =771-3 litres.
1,2965
i.e., Dividing the weight by the weight of a known volume
gives the volume.
2. Water is 773 times the weight of air. A litre or cubic decimetre of water weighs 1000 grams.  Find, from these data,
the weight of a litre of air.
e000
Here — =1' 2936 grams.
773
3. The mercury in a barometer tube is 760mm high (30 inches
nearly); the area of the tube is 3 sq. c.m.; and the cistern
contains 60 cubic centimetres. What is the cubic contents
of the tube and cistern together? Secondly, What weight
of mercury would be required (sp. gr. of mercury  13'5)?
Answer. 288 c. c.  Weight, 3888 grams=8'6091bs. ch.
4. A cylindrical gas-holder is'45mm high and 7'0686 sq. dm. area.
How manylitres of gaswillit hold? Andhow muchwouldthe
quantity of hydrogen and oxygen gases weigh respectively?
Ans. 31'8087 litres; 2'85 and 45-6 grams.
5. A gas jar is 400mm high and 50mm broad. Required, the
cubic contents. (For areaxsq. diam. by -7854.)
Ans. -7854 of a litre.
6. Another jar is 25cm high and 5cm broad. Required, its capacity in parts of a litre.
Ans.'490875 litres.
7. Two cylindrical gas jars, each 150mm high and 40mm broad.
What volume of gas will the two hold?
Ans. -376992 of a litre.




WEIGHTS AND MEASURES.                25
8. How many criths in 50 litres of hydrogen, oxygen, nitrogen,
air, and chlorine respectively? (See above data.)
Ans. 50, 800, 750, 725, 1775.
It may be useful to add a few facts by way of comparing our present system of weights and measures with the
metric system, with some examples showing the method
of conversion.
The cheap boxes of weights usually sold by instrumentmakers usually contain grains, scruples, and drachms,
apothecaries' weight, which is equivalent to the Troy
weight.  Cheap boxes of gram weights sufficiently exact
for elementary purposes are, however, now to be had.*
Liquid measures are in almost everybody's possession.
These are usually graduated into fluid ounces.      An
imperial pint contains 20 fluid ounces, a fluid ounce of
distilled water weighing exactly 1 ounce avoirdupois, or
437k grains.  Some measures are graduated into cubic
inches. A cubic inch of water weighs 252'458 grains
(nearly 252k). A litre wine bottle is easily obtained for
comparison with our liquid measure.
The imperial pint='5675 of a litre, or 34'66 cub. in.
The imperial gallon = 454 litres.
This quantity of distilled water at 62~ F. weighs 10 lbs. av.
The cubic foot = 28'315 litres or cubic decimetres.
SERIES III.
Examples to be worked out or verified by Experiment.
1. Weigh out 10 grains of sand. Find the number of grams.
2. Weigh out 1 scruple of sand. Find the number of grams.
3. Weigh out 20 grams of zinc, and find how many grains.
4. Measure out 10 fluid oz. of water, and find what part of a
litre it is.
5. Mleasure out 5 fluid oz. of water. How much would it weigh
at 62~ F.?
6. Measure out 1 litre of water. What does it weigh in grams
and grains.
* A shilling box of such weights can be obtained at Maw's, in
Aldersgate Street, London, from 5 milligrams to 10 grams. The
gram weight is only 2 milligrams out.




26               PRACTICAL CHEMISTRY.
7. What is the weight of a pint of water in grams, and its
volume in parts of a litre?
8. What is the weight of a cubic inch of water in grams?
9. How many cubic inches in 3 pints of water? What is the
volume in terms of the metric system?
10. A gas-holder contains 6 gallons of water. How many cubic
feet, and how many litres of gas will it hold.?
Ans.'96275 cubic feet, or 27'26064 litres.
11. What is the weight, in grams, of 2 scruples of potassic
chlorate?
12. What is the weight, in grams and kilograms, of 580 litres
of water?
CHAPTER III.
APPARATUS AND PRELIMINARY OPERATIONS.
10. BEFORE commencing the systematic study of the subject, the student should make himself acquainted with
the apparatus to be used, and the modes of fitting up
certain parts. This can be better done by making and
fitting up as many as possible himself, than by his buying
them ready made and fitted. IHe should not, however,
spend valuable time in making and trying to mend
apparatus that can be easily obtained at the instrumentmaker's for a small sum.
11. Glass-working. —   uch of the apparatus used by
the chemist is made of glass, which, on account of its
plastic nature when hot, enables it to take any form impressed upon it at that time. Glass tubes bent into various shapes are in constant requisition, and the student
should acquire dexterity in making these for himself.
Some of the glass tubing imported from Germany is very
difficult to fuse.*  It is hence called hard glass.  This is
* " Difficultly fusible," as it is termed, not very euphoniouslyand the same of "difficultly soluble." These terms were, however,
used by Faraday and Miller.




APPARATUS AND PRELIMINARY OPERATIONS.      27
only useful for combustion-tubes, which are required to
stand great heat. There is another kind which is more
easily worked; it is readily fused or brought into the
plastic condition, and hence called soft glass-this should
be selected. English tubing is soft, but it contains lead,
which is easily reduced on heating. French glass is also
soft, but the German soft glass is the best for fitting 1up
apparatus. The tube should be of moderate thickness;
if too thin, it bends suddenly when heated; but if too
thick, it is difficult to work.  It
is to be had of various sizes.
These are the most useful.                      O
The best flame for bending X
ordinary tubes is a fish-tail gas
burner, but the flame of a spirit-lamp will do, and a small
tube may even be bent in a candle flame. A fish-tail
burner fitted on a telescope tube with a cast-iron foot, so
that it may be raised to various heights to suit different
persons, is a valuable adjunct to a laboratory for bending
tubes, as the ordinary gas lights are often too high. If
gas be used, the soot deposited may sometimes stain the
glass, if heated too long, but does no injury, and can
generally be wiped off. Heat about an inch of the tube
where it is wished to be bent, holding it with both hands,
and turning it constantly so as to heat it regularly.
When it is found by the pressure of the hands to be soft
and yielding, remove it from the flame, and gently bend
it with the concave part from you, taking care to keelp it
in the same place.  If the concave portion be made too
hot, it is apt to buckle; if, on the other hand, the convex
part be too much heated, the tube is apt to become flattened and contracted in its channel in the course of bending. Of the two, it is better that the convex portion be
made hotter than the other. When finished, tubes should.be annealed by gradually withdrawing them from the
flame, not cooling them suddenly. Never put a hot tube
down on the bench, but support it on some badly conducting material till cold.




28              PRACTICAL CHEMISTRY.
If large tubes are to be bent, a Herepath's blow-pipe
may be used with advantage, the glass being brought
gradually into the outer flame from beyond; or a charcoal fire may be substituted.  Glass begins to soften
before a visible red heat, but the manipulator depends
more upon the touch than the eye.
Small tubes about three or four inches long, for heating
substances over the Bunsen, or blow-pipe flame, are easily
made from a bit of hard combustion tubing by means of
the Herepath, in the following manner:Take a piece of tubing about f. of an inch in diameter,
and double the length of the required tube; heat it in
-the centre, gradually at first, then strongly, and when
quite soft, pull it out suddenly, and you have two tubes.
The little adherent piece is easily removed by the scratch
of a file, and the point fused afresh.
The following extracts are from the late Professor
Faraday's admirable work on Chemical Manipulation.
12. Blowing Bulbs.-"A more delicate operation than
any yet described, and one that requires considerable practice for its performance with even moderate success, is
the blowing of bulbs, and other expansions, either in
the middle or at the end of a tube.
"Facility will be best obtained by practising with a
piece of tube about' nine or ten inches in length, onethird of an inch in diameter externally, and one-tenth of
an inch in internal diameter. The end is first to be
closed, and then about two-thirds of an inch in length of
the closed extremity is to be uniformly heated until so
soft as to bend from side to side by its own weight. The
aperture is immediately to be placed between the lips,
and by means of the mouth, air is to be propelled for the
purpose of expanding the soft glass. This must be done
quickly, but cautiously; and as soon as the eye, which
must be constantly fixed upon the heated end, perceives
enlargement there, the force exerted by the mouth should
be slightly diminished, and the operator should hold himself ready for its instantaneous cessation.  For if the




APPARATUS AND PRELIMINARY OPERATIONS.    29
power which expands the glass at first be continued in
full force, the glass will suddenly burst out into a large
irregular thin bubble of no use (fly to pieces, and forn
the so-called'frost').  This follows as a natural consequence, for every enlargement of the bubble diminishes
its thickness, and consequently, its resistance, and at the
same time increases its internal area, and in that respect
increases the power of the air impelled into it; and if
the enlargement take place quickly, so that the glass has
not time to cool, it cannot but happen that the bubble
should expand to a large size. To avoid this, air should
be thrown in from the mouth only, and not from the
lungs: as the glass expands, the force with which the air
is impelled should be diminished; and the operator
should not endeavour to finish the bulb at once, but
having succeeded in expanding it to such a size that the
internal diameter is five or six times the thickness of the
glass, he should heat it again, and complete the bulb at
a second operation.
" The glass must never be blown whilst in the flame,
but is always to be expanded in the air; as it swells, it
must be turned, and the thinnest parts brought to the
lowest position.
" If an expansion be required in the middle, the tube,
if not closed at one end, must be temporarily closed with
the finger or a cork. The glass is then to be heated
where the bulb is required, and then blown out as before."
The cut ends of tubes should always be fused, so that
they shall not cut the fingers or india-rubber connectors.
Heat gradually, about half-an-inch from the end, and
then the end itself, till the edges begin to glow.
To seal a platinum wire into a glass tube requires
some practice, and is not much wanted by a student at
first. It can be done with platinum, because the rates
of expansion and contraction of that metal are the same
as that of glass.
13. Glass-cutting.-Glass tubes are easilycut, bymaking
a notch with a sharp, three-cornered file, turning the glas




30             PRACTICAL CHEMISTRY.
rather than moving the file. Break, by grasping with
both hands, and bending with the notch away from you,
as you would snap a dry stick. If the tube be large,
carry the file-mark round, and make the notch deeper on
the side farthest from you.
Sometimes the neck of a flask we wish to keep gets
broken. The point of a hot iron passed round the tube
will frequently lead the crack, and the rough edges may
then be fused, as mentioned before. A flask, or retort
neck, may sometimes be cracked round, by tying a string
previously soaked in turpentine round the place, and
then setting fire to it, turning the flask the while.
When burnt out, invert the flask and dip it into water
up to the point; it will generally crack at the place
desired. Glass may be cut with a diamond; but it is
not likely the ordinary student will possess one. A
scratch, however, is of no use with this substance; it
must be cut.
14. Lamps.-Where gas is to be procured, the Bunsen's
Burner is the best source of heat for chemical operations, but
spirit lamps may be substituted where gas is not laid on.
The Bunsen's
burner is supplied  with   a
heavy  cast-iron
foot, into which
Ijj^ d~I-\          iis screwed a small
piece of tube to
connect it with
(i y  Hi<^~  cthe supply-pipe
Fig. 1.             by means of about
2 feet of the
brown or vulcanised india-rubber tubing 3-inch diameter. The burner is screwed to the top of the foot,
and a piece of brass tube is screwed on over this, perforated with a somewhat large hole on each side
of the base, and supplied with a moveable ring to close
the holes, if necessary. The air entering the holes is




APPARATUS AND PRELIMINARY OPERATIONS.     31
mixed with the gas as it issues from the jet, and complete combustion takes place at the top of the tube, a
very hot, non-luminous, smokeless flame being the result.
If the pressure of gas is too small, the air
mixes with the gas in the tube and explodes
it near the jet, without danger. If, however,
the pressure is too great, and it is necessary
to reduce it, the sliding ring may be so moved
as to regulate the supply of air.
If the brass tube of the Bunsen have a
worm at the. top, it may be fitted with a
brass cylinder, having a piece of fine wiregauze at the top, the base being perforated
with holes for the admission of air. This
gives a large, hot, smokeless flame for flasks,  Fig. 2.
and is called a Gauze Burner.
The Rose Burner (a, Fig. 1), to screw on to the top of
the Bunsen, is another arrangement for the same purpose.
The Chimney (b), with star support (c),
is sometimes useful.
15. The Blow-pipe Jet (d) is a piece of
brass tube, flattened at the top, which
drops into the tube of the Bunsen and
gives a thin, luminous flame, to be used
with that instrument.
A spirit-lamp, with circular wick, or
a Berzelius' lamp, in which the spirit
reservoir is at a distance from the flame,
and made to slide up and down the rod
of a ring-stand, should be furnished to
every laboratory where gas cannot be had.  Fig. 3.
16. The Blow-pipe.-Black's form is the best, having a
reservoir for the air at the bottom, which also furnishes
a means for.retaining the moisture (a).  Another form,
made of brass, is very useful for retaining the moisture
in a sphere, midway between the jet and the mouth.
It is shown in Fig. 4, (b).  The sphere is made in




32              PRACTICAL CHEMISTRY.
two pieces. It may be furnished with a bone mouthpiece.
To use the Blow-pipe.-The student must not get the
notion that he is to empty his lungs of air and then gasp
for breath.     He must, in,__    -- I~     ~the first place, inspire and
a              expire through the nose.
Placing the blow-pipe beb)- b. ~ f^   y ~tween his lips, and filling
his mouth with. air from the
Fig. 4.         lungs, he must learn to use
the muscles of the mouth to
regulate and sometimes to supply air to the instrument.
The mouth, in fact, acting the part of a distended bag,
into which the air is taken by mouthfuls, the muscles of
the cheeks and jaws propelling it forward so as to produce
a constant blast. It is not necessary to
_v.  ~    produce a strong current, the smaller
stream being as efficient as a larger
one.
17. Herepath's Gas Blow-pipe.-The
jet, furnished with flexible tube and
mouth-piece for sending the blast of
air, is usually fitted to a Bunsen; gas
Fig. 5.    being supplied by the latter.
18. Supports.-These should not be
selected for show. They are requisite to hold apparatus
in various positions, and substitutes may mostly be made
or fitted up for the occasion.
19. The Retort Stand, having a heavy foot, and furnished with 3 rings, and clips of various sizes for test-tubes
when they have to be heated for some time. Some of
the larger ones are furnished with a screw clamp, lined
with cork, to hold a flask or tube containing mercury.
A very good substitute is made with an iron rod fixed
into a wooden base, with some pieces of thick wire for
rings.
20j The Tripod may sometimes be used as a substitute




APPARATUS AND PRELIMINARY OPERATIONS.    33
for the above. Both are usually furnished with a piece of
wire gauze to lay on the top; a triangle to hold an
evaporating dish, when it may be safely exposed to the
direct flame; and a sand bath.
21. The Lamp Furnace consists of an earthenware cylinder to cover a Bunsen and form a chamber of hot air, and
is a useful addition. It is usually furnished with a dish at
the top, to be used as a water-bath for heating substances
that do not require a temperature above the boiling point of               b
water.                        "          a    b
22. The Table Support consists of a flat table fixed on a
rod which slides up and down a
tube rising from a wooden foot.
The tube is furnished with a
screw, so that the table can be 
fixed at any height.
The wooden crook (a), and
one with 3 pegs (b), fixed into
a ball, are useful, and may be      Fig. 6.
fitted to the same stand.
A few wooden blocks, 3 or 4 inches square, and from
~ an inch to 3 inches high, are handy, and
would in many instances do quite as well
as the more finished support.
23. The Wooden Vice, lined with cork
(Fig. 7), is an almost indispensable requisite.
24. The Pneumatic Trough, for the collection and transfer of gases over water,
is made either of japanned tin plate or
earthenware.  The larger kinds, as in
Fig. 8, have 2 shelves for supporting gas
jars. The small ones have a shelf for
supporting the gas jars, perforated with  Fig. 7.
two holes, having inverted funnels below
them to lead the gas into the jars. (See Fig. 8-a, page 34.)
C




34             PRACTICAL CHEMISTRY.
The stoneware trough, Fig. 9, is furnished with a beehive shelf, for the same purpose as the funnels in that
first named. Glass dishes, for smaller quantities of water,
are useful on the lecture table, on account of their transparency; but the student in the laboratory may substitute
basins instead.
A substitute for a pneumatic trough may be made as
Fig. 8.                    Fig. 8-a.
follows. Take a flower-pot, make a hole in its side, and
place it upside down in a wash-hand basin. Invert the
gas jar (filled with water), over the hole in the bottom
of the pot, and bring the
delivery- tube  through
the hole in   the side.
- =    =~ —-— /  The gas will rise through
the hole in the bottom
Fig. 9.         -into the jar. The student
should  practise  filling
jars with water, inverting them  in the trough, and
then filling them  by means of a glass tube with air
from  his lungs. He may also learn to transfer air
from one jar to another filled with water, by depressing
the jar of air with his right hand till its mouth is just




APPARATUS AND PRELIMINARY OPERATIONS.     35
below the edge of the other, then, gently tilting it, and
allowing bubbles of air to rise into the other jar. Do this
over and over again, till skill is acquired. Ie may also
fill a cylindrical jar with coal gas by means of a flexible
tube, with a piece of glass tube attached to dip just
under the surface of the water. Grease a glass plate,
bring it below the surface of the jar, slide it over the
mouth, raising it out of the water and standing it
upright on the table. Take a lighted taper in the right
hand, and slide off the greased plate with the left, apply
the light, and the gas will inflame without explosion, if care
has been taken not to mix air with it. Air may be mixed
with gas in another jar, and the flame will cause the gas
to explode without injury to the cylinder, as no obstacle
is presented to the expanded gases rushing out. Collect
a jar of coal gas, without admixture with air, and inflame
it while held in the left hand in an inverted position.
(See Fig. 23, page 69.) The gas does not escape, because
it is lighter than air. The student may also transfer a jar
of coal gas, collected at the pneumatic trough, upwards
into an empty jar, held as in Fig. 24, page 69, the gas
rising.through the air and displacing it on account of
its lightness.  Test carefully with a light.  A  slight
explosion will not injure a cylindrical jar of moderate
thickness.
Practice of this kind will be found very useful, and
may be much extended by the teacher and thoughtful
student, and manipulating pow'z' will be gained of great
value in future experiments.
The gas-holder will be described in the chapter on
oxygen.
24-a. The Mercury Trough will perhaps sometimes be
used by the teacher at his lecture; but, on account of the expense of the material, and its liability to loss, one as small
as possible may be selected. One to work with 4 lbs. of
mercury is to be had of Jackson, Barbican. It requires
careful practice to get used to filling tubes and small jars
at the mercury trough, and should first be done with no




36             PRACTICAL CHEMISTRY.
one fidgeting about.  Globules spilt may be run into
one and be swept down by the operator, so that little
loss need be really sustained.  The mercury trough
should, however, always stand in a tray or other vessel
when used.
25. A Wedgewood Pestle and Mortar is required for
pulverising substances so that they may be more freely
attacked by chemical reagents. Very hard substances,
like subphide of iron, should first be reduced to fragments
by wrapping them in paper and striking them a few
blows with a hammer on a stone or anvil.
A selection of sound corks will be necessary. Before
using them, they should be pressed, or put in paper and
rolled under the foot to soften them.
26. Cork-borers consist of 3 or 4 brass tubes, sharpened
at one end, and having a rim at the other, with a hole
through the upper part to admit of a stout wire being
put through to give greater purchase. They may be
sharpened when necessary with a fine file. A rat's tail
rasp andfile, the first for enlarging a hole made by the
cork-borer, and the latter for making it smooth, should
also be possessed by each student.
CHAPTER IV.
OPERATIONS CONTINUED.
THERE are certain operations of constant occurrence in
the Advanced course which it will be well for the beginner to know something about at once, as they occur
occasionally in the First stage, when more important
matters are pressing for attention than the mere operation itself.
27. Solution.-This followsnaturallyafterpulverisation,




OPERATIONS CONTINUED.             37
mentioned at the close of last chapter. It gives greater
mobility to the particles of bodies, preparing them for,
or producing chemical action, sometimes separating a
soluble substance from one that is insoluble. If by dissolving a substance, no alteration of properties is pro —
duced, and on evaporation the solid is again obtained, it
is a Simple solution.  If, on the other hand, chemical
action takes place, the student must know beforehand
the nature of it, as new compounds will be formed. In
a simple solution, the body exists in afree state.
28. Water is the best Solvent, and is always tried first.
Most substances are more soluble in hot than in cold
water, so that if a certain quantity dissolve in cold, more
will dissolve if the water be heated, the substance, however, frequently separating in a crystalline state as the
liquid cools.
29. Salt is equallysolublein hot and cold water, but lime
and magnesia are somewhat less soluble in hot than in
cold.
30. Acids are usually tried next to water; hydrochloric
being preferred because of the solubility of most of its
compounds; then nitric, which has a great tendency to
part with oxygen; and lastly, but rarely, sulphuric.
31. Alcohol comes next as a solvent, and solutions in this
liquid are called tinctures. Methylated Spirit will do in
most cases.
32. If a substance is insoluble, it is tasteless, but it is not
always safe to taste an unknown substance. Loaf sugar
and sugar-of-lead (Plumbic acetate), are similar in appearance, though not in weight, but the latter is poisonous.
If a substance is soluble, and a bit be suspended in water
by a thread, streams of the dissolved substance will be
seen* to descend on account of its greater density.
Solution is generally performed in test-tubes, Jlasks, or
beakers. Flasks are used when much vapour is evolved,
* Owing to its different refractive power. In this way the hot
air rising above a burning gas jet is visible passing through the
denser air.




38              PRACTICAL CHEMISTRY.
and t6 drive off the greater part of the water when a substance has to be evaporated afterwards to dryness. They
should not be put on a table when hot; they may be
supported on wire rings covered with list, or, in one of
the straw rings from the bottom of the covering of a
Florence oil flask.
Beakers are thin cylinders of glass with flat bottoms,
and are sold in nests of 3, 4, or 6 of different sizes.
Being thin, they bear sudden changes of temperature
well, and from their width admit of the stirring-rod being
used with caution. They may be supported on wiregauze, or a sand-bath on a tripod. Be careful to wipe
off the moisture that first condenses on the outside of such
thin vessels, or they will be sure to crack.  Test-tubes
may be held when hot with a band of folded paper passed
round them.
A cold liquid should not be added to another when
boiling, or, if absolutely necessary, only in small quantities at a time, either through a funnel or down a glass
rod previously wetted. On no account must it be poured
down the side of the glass.
If the whole of a liquid is to be driven off, the larger
portion may be evaporated in a flask or beaker, and
the remainder can then be poured into an Evaporating
dish.
33. Evaporating Dishes should not be exposed to the
naked flame, or at all events, the flame must not be
allowed to pass above the line of the liquid, or fracture
will result. They may be supported on wire gauze or a
sand-bath. Towards the end of an evaporation, the
substance becomes pasty and spits. It should then be
watched, and before the last drop or two has evaporated,
tie lamp should be taken away, the heat of the vessel
being sufficient to complete it.
The water-bath may be used for evaporations where
the substance would be injured by a temperature above
the boiling point.
Evaporation is often the first step to crystallisation.




OPERATIONS CONTINUED.                  39
34. Crystallisation often takes place when a substance
passes from the fluid to the solid state, taking up regular forms.   Thus common salt always crystallises in
cubes, chlorate of potash in flat tables; sulphate of zinc
in needles. To facilitate the process, the liquid must
be allowed to evaporate slowly.       Crystals frequently
separate from a hot saturated solution as the liquid cools.
Very slight changes in the physical condition of a liquid
cause crystallisation to begin.  A nucleus, or something
to attach itself to, seems often to start it. Thus if a hot
saturated solution of sodic sulphate (Glauber's salts) be
allowed to remain at rest-in a small flask, crystallisation
does not take place, but the least motion, the touching of
the surface with a glass rod, or the dropping in of a crystal, is sufficient to start it, and crystals dart through the
liquid which becomes a solid mass, the water being retained in the state of ice (water of crystallisation). 
Exp. 1. Dissolve some common alum in a large boiling tube
(large test-tube), heating and adding the substance till no more
will dissolve. Stretch some strings or bits of worsted across a
saucer or other shallow vessel, pour the solution of alum into it,
and put it aside in a warm place. Or, a bit of coke may be
put into the solution. Crystals like double pyramids will form
around it.
Large crystals may be obtained by selecting some of the most
perfect and putting them into a separate vessel containing a
saturated solution of the salt, turning them over daily with a
piece of stick on to a different face, replacing the liquid every few
days by a fresh cold saturated solution, after draining off the
"mother liquid." Substances which crystallise in the same forms,
and are similar in atomic constitution, are said to be isomorphous.
Thus chrome alum, though not the same in composition as
common alum, crystallises in the same form, and very pretty
crystals may be obtained by adding a solution of this substance
to that mentioned in the above experiment.
Some substances crystallise in two forms, and are hence dimor.
phous.  Thus sulphur crystallises from the state of fusion in
needles, but from its solution in bisulphide of carbon in octahedrons.
Substances which do not assume the crystalline state are said
to be amorphous.
85. Filters and Filtration.-Packets of filter paper may




40               PRACTICAL CHEMISTRY.
be purchased of the proper sizes to fit 2" and 3" funnels
(the most useful sizes), which are used to support them.
Stout white blotting-paper may be used, or the filter
paper may be bought in sheets and cut to sizes by means
of circular discs of tin plate or Mohr's filter cutters. To
fix the filter, fold the filter paper in half, then again at
right angles, and open out by leaving three thicknesses
on one side and one on the other, as in a, b, c.
The filter is to be put into
a glass funnel, which should
be made with its sides sloping
at an angle of 600, in order
a      that circular filters may fit
accurately.  The funnel may
be supported on the ring of
a retort stand, or by a triangle
on a tripod over a beaker.
V3  f ~ ^      The end of the      funnel
b          tube should enter or touch
the side of the beaker to prevent splashing.
36. Decantation or pouring off may sometimes be resorted to instead of filtration.
Exp. 2. Mix together some sand and salt.  Fold a piece of
writing paper, and shoot some of the mixture into a dry test-tube.
Half fill with water and shake, the salt will dissolve. Fold a filter
as above directed and put it in a glass funnel, supported by a ring
of the retort stand with a beaker below. Wet the side of the filter
by a stream of water projected from the wash-bottle afterwards
described. Pour the whole of the contents of the test-tube carefully on the filter; the clear liquid called the filtrate which runs
through will contain the salt in solution, which may be tested by
its taste.
Liquids may be poured down a wetted rod into a funnel in the
way previously described.  The student may practise the separation of the constituents of gunpowder as mentioned in Chap.
I.; 6r, at all events, he may dissolve out the nitre and test it.
37. The Wash-Bottle consists of a 30-oz. German
flask, or a Winchester pint will answer very well if
it can be got with a wide mouth.         A   sound cork




OPERATIONS CONTINUED.             41
must be fitted with two tubes bent in the following
manner.   One tube must be bent at an        obtuse
angle, and be just passed through the cork.     The
other must pass through the cork to the bottom of
the flask, and must be bent externally at an acute
angle, and terminate in a jet as in Fig. 10.
The bottle being filled with water, and the mouth
applied to the first tube, air is to be forced in, and the
increased pressure drives the water
up the second tube and out at the
jet. Its use is to wet a filter and 
to wash down particles from   its
sides.  The jet may be attached
by a piece of flexible tubing, so
that it can be turned about at
pleasure, without shifting the position of the bottle.
38. Distillation is not much required in Inorganic Chemistry. It
consists of separating one fluid from
another, the former being more vol-    Fig. 1
atile; or in separating a fluid from a solid, the former
being wanted and the solid not.
It is carried on best in retorts. These should be light
and free from specks or flaws, which are liable to make
them  crack when heat is applied.  If stoppered, the
opening called the tubulature should be in the centre of
the body, so that substances poured in shall not soil
the neck. It frequently happens that more materials
have to be added whilst the operation is proceeding. If
so, the powder should be added gradually, being shot in
from a piece of glazed paper, and if liquid, by means of a
thistle-headed funnel. It is better, however, to stop the
operation to add new materials, and shake or whirl the
retort round, as solid substances are apt to sink to the
bottom. The tube of the retort is generally passed into
a globular receiver made for the purpose, but a clean
flask of any kind will do, so that the neck is wide




42               PRACTICAL CHEMISTRY.
enough to admit the tube of the retort. No cork is needed.
Cold water must either be allowed to drip on the
receiver when distillation is going on, or wet cloths
or blotting-paper must be put on it to condense the
liquid, called the distillate, which comes over.
Exp. 3. Put half a gill of port wine into a 2-oz. retort, and
pass the tube
into a receiver
or Florenceflask
standing in a
basin containingwater,covering the latter
with a wet cloth
or some wetted
blotting-paper.
ElJ    1        //  X     s\\o\m, w e Heat the retort
on a sand-bath,
yvapours   will
pass over and
condense in the
Fig. 11.                receiver, which
by their spirituous taste will be recognised as bra.udy. The residue
in the flask is little more than coloured water. If the distillation
be carried on too long, water will evaporate also, but the spirit
being more volatile, comes over first.
Cognac Brandy is distilled from  the lees or refuse in
the wine manufacture.
39. Clark's Retort and Receiver is handy for distilling
small quantities, and will be mentioned under the head
of nitric acid. (Fig. 40, page 119.)
40. For distilling large quantities the chemist uses a
Liebig's condenser, where the condensing surface is increased by surrounding a long tube by a wide tube containing water, called a water-jacket.
41. Sublimation differs from distillation in the nature of
the product, being a solid, as in the refining of crude
sulphur.   The.materials are melted, and the sulphur
being volatile, is allowed to pass into a cool chamber,
where it oondenses in the form offlowers of sulphur.
Exp. 4. Pit a few grains of iodine into a clean Florence flask and
heat gently; the substance volatilises, violet vapours filling the
flask and cooling on the sides in a crystalline form,




ACTION OF THE ALKALI METALS.            43
CHAPTER V.
ACTION OF THE ALKALI METALS POTASSIUM AND SODIUM ON
WATER, HYDROCHLORIC ACID, AND AMMONIA.
42. Water was called by the ancients one of the elements,
although, doubtless, they did not use the term with
the same meaning as we do now. Let us endeavour to
understand something further about its composition.
On page 14, we learned that it could be converted by
heat into invisible steam: this steam occupies about
1700 times the space of the water that'produced it-but
its molecules, though repelled from each other by the
force of heat, are still water. The intense heat, however,
of a succession of electric sparks passed through steam
separates its molecules into gases, in other words, decomposes the steam. The experiment, however, is somewhat
too difficult for a beginner to perform, and requires an
induction coil.
Some metals have no effect upon water at any temperature, as gold, silver, and platinum; others, as copper,
iron, and tin, decompose it at a red heat; whilst the
metals, potassium and sodium deconmpose it at ordinary
temperatures.
Exp. 1. Get some of the metal potassium, which is prepared
from-wood ashes.  It must be kept in petroleum, as this liquid
contains no oxygen, for which it has a great
affinity. It is soft, and when cut with a knife,
is bluish-white.  Take a bit the size of a pea, _  ii
throw it into a basin or little glass dish contain-  "'
ing water; it will ignite, burning with a 
characteristic violet flame. It will roll over the
surface of the water (being lighter than that
liquid), making a hissing noise, giving off white
fumes, and disappear at last with a slight
explosion. On this account it will be advisable
to have a glass plate at hand to cover the dish, as  Fig. 12,
a piece of the hot metal is sometimes thrown out.
The potassium tears asunder the moceuksl of Water with which




44                 PRACTICAL CHEMISTRY.
it comes in contact, liberates apart of the Hydrogen, which fornmed
one of its constituents, combining with the other part, and the
remaining constituent, to form caustic potash or potassic hydrate.
The latter may be seen as a white streak, dissolving'in the water,
to which it gives a peculiar taste, called alkaline.  A yellow turmeric paper, which is not affected by ordinary water, will be turned
brown upon being dipped into that in which the potassic hydrate is
dissolved. A reddened litmus paper will be turned blue. This is
called a basic or alkaline reaction.
Exp. 2. Take a piece of the metal sodium, it is cheaper than
potassium, being one of the constituents of conmon salt. It is
soft, like potassium, and lighter than water; but its action is not
so violent. Throw a piece upon water, it will roll about, but will
not inflame unless the water be hot, or its motion be arrested by
putting it on a bit of blotting-paper; then it will do so, burning
with a golden yellow flame. Cover with a glass plate before the
flame is extinguished, as in the previous experiment.
C(austic soda, or sodic hydrate, will be formed in the same way
as potassic hydrate was, hydrogen being set free; the same taste
and basic reaction being also produced in this case.
Exp. 3. Fill a small cylinder or large test-tube with water,
cover the mouth with a greased glass plate, and invert it in a
b lsin of water. Wrap a bit of sodium in
fi ie wire gauze, and throw it into water,
(t w; M r     it will sink on account of the weight of the
latter. Bring the cylinder over it, bubbles
of gas will rise and displace the water,
speedily filling the tube.  Cover with the
thumb, or a greased glass plate, and remove
* from the water. The gas is transparent and
calourless, and inflames when a light is
applied, burning with a pale lambent flame.
Fi. 18.    It is hydrogen, which has been liberated
from the water.
Another, and perhaps a better way, is to get about an inch of tin
pipe (such as used by gasfitters). Perforate it with holes, and then
put a bit of sodium into it. Flatten the ends of the pipe to close
them, and drop it into the water. Streams of Hydrogen will rise
fiom the holes where the water comes in contact with the metal.
The sodium decomposes the water, as in the case of the potassium.
Potassium must not be used, as the heat produced by the violent
chemical action would inflame the gas. Care is necessary, even
with sodium.
A pair of brass tongs having a bowl something like a bulletmould, but perforated with holes, is very handy for this experiment, as they can be brought under a cylinder readily, and do




ACTION OF THE ALKALI METALS.              45
not let the sodium escape and take fire, as it sometimes does,
inflaming the hydrogen.  They must be wiped dry if a second
piece of metal has to be used. A
wire-gauze spoon may be inverted 
over a bit of the metal as it
floats on the surface of the water,
and thus be brought under the
cylinder.
Water, however, is not the
only liquid from   which hydrogen can be obtained by
means of the alkali metals,              Fig. 14.
potassium and sodium. Two
liquids, hydrochloric acid and ammonia, having very
opposite properties with regard to their action on testpapers, yield this gas under certain conditions.
43. Hydrochloric acid is a gas, very soluble in water, its
solution being kept in the laboratory under the same
name.   A blue litmus paper is instantly turrned red when
held over the open mouth of a bottle containing it.
44. Ammonia is also a gas, and its solution in water is
kept by the chemist as a common reagent. It has the
property of turning a reddened litmus paper blue and a
turmeric paper brown, and is sometimes called the volatile
alkali, to distinguish it from the fixed alkalies, potash,
and soda.
These two liquids give off their respective gases when
heated, as they are held simply in solution, and are more
volatile than the water in which they are dissolved.
Exp. 4. Fit up a 4-ounce flask with a thistle funnel, and a
delivery-tube bent twice at right angles, as in Fig. 15. The funneltube must go nearly to the bottom of the flask, the delivery-tube
just passing through the cork. The longer leg of the latter must
pass through the cork of a rather wide-mouthed bottle nearly to
the bottom, and from the top of this bottle another elbow-tube is
to be fitted, to which a piece of hard glass tube is to be attached,
or a bulb-tube, if one be at hand.
Pour into the flask (a) a small quantity of strong solution of
commercial hydrochloric acid, and half fill a bottle with pieces
of pumice stone, saturated with strong sulphuric acid (oil
of vitriol). Put a piece of potassium into the bulb of the tube (c).
Heat the hydrochloric acid gently in the flask over a sand-bath




46                PRACTICAL CHEMISTRY.
the gas charged with moisture will pass out into the bottle,
where it will be robbed of its moisture by the sulphuric acid
spread over the large surfaces of pumice (dessicating agent), and
the gas will pass off dry through the bulb-tube (c); or pass the
moist gas through a bent tube containing chloride of calcium as
Fig. 15.
in Fig. 15, the gas will be dried. It will redden a blue litmus paper
held at the open end, and fumes in air, dissolving in its moisture.
Now, heat the potassium in the bulb (c), by means of a spirit
lamp. Chemical action will be set up, and the metal will glow.
The hydrochloric acid gas will be decomposed, one of its constituents-chlorine-combining with the potassium to form potassic
chloride, the other being set free.
Apply a light to the end of the tube; a gas inflames, which
is hydrogen, the other constituent of hydrochloric acid.
Exp. 5. In the same manner, and with the same arrangement
of apparatus, ammonia gas may be proved to contain hydrogen,
the other constituent combining with the metal. The gas obtained
by heating the solution must be dried, however, by passing
it through quick-lime as a dessicating agent, as sulphuric
acid forms a compound with ammonia. Chloride of calcium in
a U tube might be used in both cases for drying the gases instead
of the above. A test-tube containing sodium amalgam-made by
putting bits of the metal into mercury, slightly warmed in an
evaporating dish-may be used instead of potassium in both experiments, and heat need not be applied.
We have seen, therefore, that water, hydrochloric acid,
and ammonia, all contain hydrogen as one of their con



ACTION OF THE ALKALI METALS.         47
stituents, and this has been separated from them by means
of potassium and sodium, which have a great affinity for
the other constituents contained in these compounds. It
is only possible, however, by this means, to separate one
constituent.
We shall, in the next chapter, proceed to show the nature of the other constituents contained in these bodies.
SUMMARY OF CHAPTER V.
Water was called an element by the ancients.
The attraction of cohesion is loosened by heat. The'heat of a series of electric sparks decomposes steam.
Potassium burns with a violet flame. Sodium burns
with a golden yellow flame.
Both metals are soft, and can be cut with a knife. They
are both lighter than water. Take care of sudden burst
of steam. The metals move about on a cushion of steam.
Potassium and sodium tear asunder the molecules of
water, hydrochloric acid, and ammonia-decompose them,
in other words-liberating part of the hydrogen in water,
combining with the other part and the other constituent
to form potassic and sodic hydrates, which dissolve in
the water. These bodies have a basic or alkaline reaction on test-papers, turning turmeric brown and reddened
litmus blue. They give the water a peculiar taste, and
make it slimy to the touch.
Sodium is not so violent in its action as potassium.
Sodium amalgam may be substituted for potassium.
Hydrogen gas can be collected.over water by bringing
a bit of sodium below an inverted vessel filled with water,
the hydrogen replacing that liquid on account of the
greater lightness of the gas.
Hydrogen is a transparent, colourless gas, without
taste or smell. It is inflammable, and burns quietly
down the jar.
Potassic, or sodic chloride or nitride, is formed when
hydrochloric acid or ammonia gas is passed over these
metals heated in a bulb-tube.




48               PRACTICAL CHEMISTRY.
CHAPTER VI.
DECOMPOSITION OF HYDROCHLORIC ACID, WATER, AND AMMONIA,
BY THE ELECTRIC CURRENT-CONSTITUENTS OF THESE LIQUIDS
— ANALYSIS AND SYNTHESIS-ELEMENTS AND COMPOUNDSCHLOROUS AND BASYLOUS ELEMENTS.
45. FOR the experiments in this chapter, it will be necessary to have some means of generating an electric current
by chemical action-that is, we must have some form of
galvanic' battery. Grove's, Bunsen's, or Smee's are the
best.  It is advisable to have four or five cells,* but two
4-inch of Bunsen's or Grove's arrangement will enable the
teacher or student to perform the necessary experiments
on a small scale, if also provided with a few other bits
of apparatus, to be mentioned as we proceed.. One cell
is insufficient to produce electric decomposition, as it is
unable to overcome the resistance a liquid opposes to the
passage of the current.
Exp. 1. a. Get two pieces of platinum foil, and fasten a copper,
or better, a platinum wire to each by making two pin-holes in the
slips, and clamping the wires. Pour some'hydrochloric acid into
a beaker, and having set two cells of your battery in action, connect one slip of platinum with each pole. Dip the plates into the
acid, bubbles of gas will be seen to arise from each of them, and a
pungent, suffocating smell will be experienced. If a moistened
litmus paper be held over the beaker it will be bleached.
b. Wash the plates well, and then dip them into another beaker
containing water. A similar result will take place, bubbles of
gas rising from each plate, but this time there will be no pungent
smell.
c. Thirdly, dip the plates into a beaker containing a strong
solution of ammonia, bubbles of gas will arise also in this instance.
* Five 4-inch cells of Bunsen's arrangement require 14 oz. by
weight, or about 10 fluid oz. (1 a pint), of strong nitric acid
to charge the porous cells; and 1 pint of dilute sulphuric acid
(1 acid to 6 water) to charge outer cells containing amalgamated
zinc plates. The nitric acid should be renewed every third or
fourth time it is used, new dilute sulphuric acid every other time.




DECOMPOSITION BY THE ELECTRIC CURRENT.         49
In all three cases the liquids are decomposed by the
electric current, which passes through the liquid from
plate to plate.
Exp. 2. Get a U or V shaped tube, or make one. Fit it to a
stand by clamping it with a piece of tin or with some plaster of
Paris. Fit two good corks into it, making a small hole through
Fig. 16.
each, and pass the wires attached to the platinum plates used in
the previous experiments through them, so that the plates will
dip into the tubes, as in Fig. 16. Half fill the tube with hydrochloric acid. Put the corks in tightly and connect the wires with
the battery. The gases arising from each plate, as in the previous
experiments, will collect now in the two limbs of the tube separately (of course mixed with air in this arrangement).
When the operation has been going on-say for five minutes -
uncork the tube connected with the negative (-) or zinc end of the
battery, a colourless gas, which inflames when a light is applied,
is found to be present, and will be easily recognised as hydrogen.
Remove the cork from the other limb, in which the plate connected with the positive (+) pole was put, the pungent smell
spoken of before will be perceived.  If a moistened litmus or
turmeric pi-per be held over the tube, it will be bleached; or, if
some solution of sulphate of indigo be previously introduced into
this limb, it will be decolourised. The gas, which has a greenish
yellow colour, is chlorine, and this bleaching property is one of
its chief characteristics.
46. Hence we learn that hydrochloric acid consists of
two gases-hydrogen and chlorine. Exact experiments
moreover show that these gases are liberated from that
liquid in equal volumes. These are, however, somewhat
D




50               PRACTICAL CHEMISTRY.
too advanced to be introduced or described at this stage.
Chlorine is rather soluble in water, hydrogen only to a
very small extent.
In the last chapter it was shown that the metal
potassium  turned out one of the constituents from   hydrochloric acid, water, etc., but the electric current sets
them  both free.  It in fact tears asunder each molecule
of the acid, which consists of an atom of hydrogen combined with an atom of chlorine.
Exp. 3. Get a small voltameter, consisting of a receiver fixed to
a stand, having two
slips of platinum foil
A'  f^  ilL  cemented into the hottom, connectedbycopper wires with two
binding screws.  Fit
it with a cork and deFig. I7.               livery-tube, as in the
&'gll *the apafigure.
Fill the apparatus with water, to which a small quantity of
sulphuric acid has been added, to increase its conducting power.
Send the current from the battery through it; two gases will
stream off at the platinum plates, which may be collected over
water in a soda-water bottle or stout glass tube. The electric current in passing through the water tears its molecules asunder,
and the resulting gases mix together in the bottle.
Cover the mouth with a greased glass plate, and remove the
bottle from the water. Wrap it round with a duster, to protect
the hand in case of fracture.  Remove the greased plate and
get some one to apply a light; a loud explosion will take place,
caused by the rushing together of the atoms of the mixed gases
to form water gas, which speedily condenses to water on the sides
of the bottle.
A substitute for the voltameter above described may be made
by fitting the two platinum plates to a cork in a wide-mouthed
bottle, the cork being also furnished with a delivery tube. If,
however, the current be strong, the exposed platinum is apt to
become red-hot and fire the mixture, blowing out the cork.
Exp.'4. Make some soap:suds in a basin, and let the deliverytube from the voltameter in the last experiment pass into it and
blow some bubbles. Take some of these in the palm of the hand.
Stand away from the voltameter, and apply a light, thi bubbles
will burst with a loud report, but of course will do no injury to
the hand. Or, remove the delivery-tube, and apply a light to the
bubbles in the basin.




DECOMPOSITION BY THE ELECTRIC CURRENT.      51
A small collodion balloon may be filled with the
mixed gases and exploded as it ascends by attaching a
piece of string soaked in strong solution of nitre, with a
bit of lighted gun-cotton at the end.
47. In all these cases chemical combination takesplace,
WATER being formed again from the constituents.
Let us now, as in the case of hydrochloric acid, collect
the two gases separately. This we may do by means of
the same arrangement with a U tube, but it is better
done in the following manner: Get two holes drilled in
the bottom of a glass basin, and cement two pieces of
platinum foil in the bottom, with copper wires attached,
passing through the holes. Two equal-sized test-tubes
are to be inverted over the platinum plates. A very
neat and not expensive instrument of this kind is shown
in Fig. 18. It is also called a voltameter, and is used
for collecting the gases separately.
Exp. 5. Fill the tubes and half fill the basin with water, adding
some sulphuric acid to both to increase the conducting power.
Invert the tubes over the slips of platinum and connect with the
battery. The current in passing from plate to plate will decompose the water, the gas rising in the tube over the plate connected with the negative
pole being double in quan-.
tity to -that which rises
over the plate connected
with the positive pole. 
Stopping  the current
whena small quantity ofgas
has collected, removing the
tube over the negative pole 
by means of a glass plate,
and applying a light, it will
be found to be hydrogen.
Removing the other tube
and plunging a glowing
splinter into the gas, it          Fig. 18.
will be rekindled, with a
slight pop, if the tube have much gas in it. This gas is oxygen,
the other constituent of the water.
48. In this case s.-e not only learn that water consists of
two gases-oxygen and hydrogen —but we find they are




52               PRACTICAL CHEMISTRY.
liberated in the proportion of one volume of the former
to two of the latter.
Exp. 6. Make the same arrangement with a U tube as in
the case of hydrochloric acid. Pour in some strong ammonia
solution, and add cautiously a few drops of sulphuric acid, to increase its conducting power. Connect the plates with the battery;
hydrogen again appears at the negative pole, and may be tested in
the usual manner. On removing the cork from the other tube and
applying a light, it will be extinguished by a small quantity of gas
which has collected there. This gas is nitrogen, the other constituent of ammonia.
49. Exact experiments show that three volumes of
hydrogen are combined with one volume of nitrogen
in ammonia.
We have thus shown by analysis the constitution of
the three compounds-hydrochloric acid, water, and
ammonia, and it now remains for us to prove as far as
possible, by putting the constituents of these substances
together (that is, by synthesis), that these compounds
are formed again.
To do this the following experiments must be performed: fuller particulars for preparing and collecting
the gases will be found on pages 66 and 67.
Exp. 7. Put some zinc clippings into a Woulff's bottle, fitted
with a thistle funnel and delivery tube. Pour on them some
common hydrochloric acid. The acid will be decomposed, the
hydrogen being liberated. Collect a jar of the gas over water at
the pneumatic trough, and cover it with a greased glass plate.
Chlorine may be obtained from hydrochloric acid by
the action of black oxide of manganese, or manganic
dioxide.
Exp. 8. Put into a 4-oz. flask (or Florence flask) some of this
manganic dioxide, and pour on it some hydrochloric acid, carefully
mixing it, so that all the powder shall be wetted and made into
a thin paste. Fit a cork and delivery-tube to the flask, and let
the latter pass to the bottom of ajar as in Fig. 19, the jar being
of the same size as that in the previous Exp.  Cover the jar
with a card having a hole in the middle or a notch at the
side.  Heat the flask  gently over a sand-bath.  Chlorine
gas will come off and lift the air out of the jar on account of its
greater density.  Great care must be taken not to let any
escape into the air, as it is poisonous, unless largely mixed




DECOMPOSITION BY THE ELECTRIC CURRENT.         53
with air (see Chap. IX.). Apply a moistened test-paper to the
mouth of the jar from time to time, and when this is bleached
the jar may be considered full.
Exp. 9. Cover the jar with
a greased plate, and invert
it over the one containing the
hydrogen. Holding the jars
firmly, draw the two plates
from between them. The two
gases will mix together, the
heavier gas descending and the
lighter ascending-diffusing,
as it is called. This may be assisted by turning them up and
down once or twice. The gases, however, only mix, they do not
combine.
Light a spirit lamp, and holding a cylinder in
each hand, bring themf to the flame and separate them
as in Fig. 21. An explosion will take place, and dense
white clouds will be produced, which redden litmus
paper. They consist of hydrochloric acid, showing
conclusively that hydrogen and chlorine are the
only constituents of hydrochloric acid. They combine, moreover, in equal volumes; one volume of
hydrogen combining with one volume of chlorine to
form two volumes of hydrochloric acid gas. The Fig. 20.
relative weights of these vols. being as 1 to 35-5,
chlorine being 35- times the weight of hydrogen. The weight
of the product is the sum of the two.
To prove the composition of water synthetically.
Exp. 10. Take the stout tube (explosion tube) used in a former Exp., or the
soda-water bottle, and fill with water.
Ascertain its measure in fluid ounces or
in any other way. Divide its volume
into three parts, and pour one-third
part of the water into the tube, pasting
a piece of paper or putting an indiarubber band round to mark the height.
Pour in another third of the water, and    Fig. 21.
mark its position by another. band.
One-third of the tube will be left. This is calibrating a tube.
Now, fill the tube with water and invert it in the trough. Fill
it two-thirds with hydrogen and one-third with oxygen, which is to
be prepared thus:
Exp. 11. Take a small test-tube of hard glass. Fit it with a
cork and delivery-tube, and put in it some oxygen mi~xture (see
Chap. XI.). Heat in the Bunsen flame; a colourless gas will




54              PRACTICAL CHEMISTRY.
be given off, which is to be collected in the above tube at the
pneumatic trough.
The explosion tube being now filled with a mixture of ~ hydrogen
and j oxygen, cover it with a greased plate and remove it from
the trough. Bring the open mouth of the tube to the flame of
the spirit lamp, a loud explosion will be the result, and water is
formed. If more or less than i of hydrogen, or more or less than
3 of oxygen be present, the explosion will not be so loud, and
some of the gas in excess will be left free.
Note.-A small test-tube of oxygen may be collected first. The gas will
rekindle a glowing splinter.
50. In this case two volumes of hydrogen combine with
one volume of oxygen to form water.
Exact experiments to be mentioned hereafter prove
also that the two volumes of hydrogen, combining with
one of oxygen, form only two volumes of water vapourthat condensation thus takes place.
The weights of oxygen and hydrogen entering into
combination are as 16 to 2-oxygen being 16 times the
weight of the same volume of hydrogen. The product
of the combination is the sum-18 parts by weight.
51. Now, there is no method known by which hydrogen
can be made to combine directly with nitrogen, so
that the composition of ammonia cannot be proved
SYNTHETICALLY, as in the other two cases. But in
any given quantity of ammonia gas, it is found that for
every 3 parts by weight of hydrogen liberated, there are
14 parts by weight of nitrogen. And, moreover, if
electric sparks be sent through ammonia gas in the sparkstream apparatus, the gas is decomposed, and its volume
becomes doubled. That is, 2 volumes of ammonia gas
become 4 volumes on decomposition; hence we infer that
3 volumes of hydrogen, and 1 volume of nitrogen (weighing 14 compared with hydrogen as unity) are condensed
to two volumes of ammonia gas.
We have in this way become acquainted with certain
elements contained in the three compounds, hydrochloric
acid, water, and ammonia, and have learned by the way
some of their properties. These compounds are types
of many others built upon the same plan.




DECOMPOSITION BY THE ELECTRIC CURRENT.   55
It was found in the electric decomposition of these
compounds, that hydrogen always appeared at the negative pole; on this account it is called an electro-positive
element (oppositely electrified bodies always attracting
each other), the term basylous being sometimes applied.
On the other hand, the elements chlorine, oxygen, and
nitrogen, appeared at the positive pole; and are hence
called electro-negative elements-the term chlorous being
frequently applied to them from the first named.
The elements are therefore sometimes divided into two
groups according to the way they behave when submitted to the electric current.
Thus, the following elements are chlorous or electronegative to the others, which are more or less electropositive or basylous:-Fluorine, chlorine, bromine,
iodine, oxygen, sulphur. Chemical affinity is greatest
between a chlorous and a basylous element, but combination takes place at times between two of the chlorous or
between two of the basylous class. Mercury, for instance,
is chlorous to sodium, but basylous to chlorine; the second
compound is, however, much more stable (not so easily
decomposed) than the first.
Fluorine is more negative than chlorine; chlorine
more negative than bromine; and bromine than iodine.
Hence, if bromine be added to potassic iodide, the iodine
is liberated and potassic bromide formed. If chlorine
be passed into a solution of potassic bromide, bromine is
liberated and potassic chloride formed.  In the same
way oxygen is more negative than sulphur, and so on.
A table of the most common elements will be given
in the next chapter.




56             PRACTICAL CHEMISTRY.
CHAPTER VII.
COMBINATION BY VOLUME AND WEIGHT-TABLE OF THE ELEMENTS
ATOMICITY OF THE ELEMENTS - COMPOUND RADICALS -
CHEMICAL NOMENCLATURE-ACIDS, BASES, AND SALTSCHEMICAL EQUATIONS.
52. As this book is intended to furnish the student principally with the practical details of the subject, the writer
would refer to the numerous works already published for
fuller information on the theoretical part, as space cannot be allotted to both.
Something, however, must be said about the nomenclature used, and the modes of expressing the composition
of bodies, and their reactions upon one another, in order
to avoid too frequent explanation of similar matters.
It has been shown in the previous chapter, by the
electric decomposition of hydrochloric acid, water, and
ammonia, that these bodies were built up of certain elements combined together in certain proportions by volume
and weight. Thus:1 vol. of hydrogen combined with 1 vol. of chlorine forms
2 vols. of hydrochloric acid gas.
2 vols. of hydrogen and 1 vol. of oxygen,-2 vols. of water gas.
3 vols. of hydrogen and 1 vol. of nitrogen, form 2 vols. of
ammonia gas.
Taking the weight of a litre of hydrogen as unity = 1,
a litre of chlorine weighs 35-5 (352), a litre of oxygen
16, and a litre of nitrogen 14 times as much. But as
gases expand by heat and under diminished pressure, and
contract on cooling and under increased pressure, it is
necessary to compare them at the same temperature and
pressure. These weights are called the volume weights
or specific gravities of these gases compared with hydrogen, and the same holds true of others.
Now the weights entering into combination in the
typical compounds taken are:-In hydrochloric acid, 1
of hydrogen to 35 5 of chlorine; in water, 2 of hydrogen
to 16 of oxygen; and in ammonia, 3 of hydrogen to 14
of nitrogen. To these may be added afourth type, which




COMBINATION BY VOLUME AND WEIGHT.      57
consists of 4 parts by weight of hydrogen combined with
12 parts by weight of carbon, forming marsh gas.
The volumes and weights of the elements thus corn
bined form in all cases molecules, which measure the
same as 2 volumes of hydrogen.
Thus chemical combination can be expressed by volume
in cases where the elements can be obtained in the state
of vapour or gas, and in all cases by weight.
Thus, to each element a number has been assigned,
showing its relative weight compared with hydrogen as
unity. This is supposed to be the weight of the " atom,"
and hence the term atomic weight.
It is usual for the chemist to use a set of symbols to
represent the elements-a sort of chemical shorthand, in
fact. The initial letter of the common, or sometimes
that of the Latin name, is used for this purpose. This
symbol also, by remembering or referring to the atomic
weight of the substance, expresses the quantity by weight
of the substance entering into combination. Thus O not
only denotes oxygen, but an atom or 16 parts by weight
of that element; H, an atom or 1 part by weight of hydrogen; C1, an atom of chlorine, or 35-5 parts by weight;
N, an atom, or 14 parts by weight of nitrogen; C, an
atom, or 12 parts by weight of carbon. Two or more
atoms of an element are expressed by a small figure
placed below the symbol on the right, as H2. The symbol
also expresses 1 volume of the elements in the gaseous
state.
When the names of two elements begin with the same
letter, a second is added to that most recently discovered,
as C1. for chlorine, Br. for bromine, Pb. (Lat. plumbun)
for lead; C. standing for carbon, B. for boron, and P.
for phosphorus.
The names of the more important elements are printed
in the following table in the largest type.
The symbols of the elements forming a compound are
written side by side, with small figures as above, if more
than one atom of either element is used, as CH,, Fe208.




TABLE OF MOST IMPORTANT ELEMENTS. 
NON-METALLIC (fIetalloids).                           METALLIC..  ~. ~
Hydrogen,. H'       1   Aluminium,... A1i         27'5  Magnesium,...      Mg"    24.
Chlorine,. C1'     35-5  Antimony (Stibium),  Sbv  122   Manganese,....Mn           55 
Bromine,. Br'     80   Arsenic,...      Asv  75  Mercury (Hydrargyrum), Hg"   200      W
Iodine,..        127   Barium,.. Ba"    137   Nickel,.Niv                  58.8:
Fluorine,. F'     19   Bismuth,...Biv     208   Palladiu,              Pdi' 106'5     G
Oxygen,.    0"     16   Cadmium,...   Cd"  112    Platinum.....Ptiv        197-1 
Boron,.            11   Calcium,..         Ca"    40   Potassium (Kalium),.K'      39 
Carbon,.   C'     12   Chromium,..   Cr     525  Silver (Argentum),..Ag'    108
Silicon,..Si"    28'5  Cobalt,..Co                58-8 Sodium (Natrium),.    Na'    23
Nitrogen,. N       14   Copper (Cuprum),.Cu"      63'5  Strontium,..S...       r"   87'5
Sulphur,. Si     32    Gold (Aurum),..Au"' 1967      Thallium,...     T'    204
Selenium,    Sev   79    Iron,.....Fe             56    Tin (Stannum),..   Sn    118
Phosphorus,  Pv    31    Lead (Plumbum),      Pbiv 207    Zinc,.....          Zn"    65
Lithium,....Li'        7




COMBINATION BY VOLUME AND WEIGHT.  59
E; 0rt~~-HTl~
i    ii _I_  II  II
-   i   -  - -  -
I!   II   II   II,I.           I
II   I    III
I I|IrIII      II
O             -
~I |~      ^




60              PRACTICAL CHEMISTRY.
The symbols of a compound thus written are called its
formula, and represent one molecule. Two or more molecules are shown by a figure on the left of the symbols, as
2HC1, 40H2-the figure multiplying the atoms of all
the elements in the molecule. Thus, in the first instance
given, there would be two atoms of hydrogen and two
atoms of chlorine combined, forming two molecules of
hydrochloric acid; whilst in the second case there would
be four atoms of oxygen, and four times two, or eight
atoms, of hydrogen, representing four molecules of water.
As a means of further illustrating this subject, the
combination by volume to form the typical compounds
before mentioned is given on page 59 here, as represented pictorially by Dr Hofmann.*
The weight of the double volumes (molecules of compound gases) being divided by 2, gives, of course, the single
volume weight of the respective compounds. Thus:H  C1         Volume wt. H  O     Vol. wt.
H  C1       of HCl            Water Gas.
1+ 35'5   36'5          2- +16  18
18'25              - 9;
2           --  2 -    2      2
if N,     Vol. wt.  H          Vol. wt.
11 ~N    of NH              of Marsh Gas.
3+14    17            4+ 12     16
2   =2 =8-5; and --     -        = 8
It will be seen by the examples already adduced, that
the elements C1, O, N, and C have very different powers
of entering into combination with hydrogen, and so
it is with other elements. One atom of C1 can only
combine with one atom of H, whilst an atom of O can
combine with two, N with three, and C with four atoms
of the same element. Hence an atom of 0 is able to
replace, or is equivalent to, two atoms of Cl; an atom of
N to three, and an atom of C to four of chlorine or
hydrogen. And so of other elements: an atom of potas* A series of card-board boxes'can be easily obtained to fit into
one another (a nest), to show this combination by volume, and
the condensation in all cases (but the first) to the double unitvolume.




COMBINATION BY VOLUME AND WEIGHT.            61
sium (K), sodium (Na.), or silver (Ag.), combines with a
single atom  of chlorine to form  KC1, NaC1, or AgClpotassic, sodic, or argentic chlorides; but it requires two
atoms of these metals to combine with one of oxygen to
form  potassic, sodic, or argentic oxides.    Again, the
metals magnesium, bismuth, platinum, and antimony
require two, three, four, and five atoms respectively to
form MgC12, BiCOl, PtCl4, and SbC5, the chlorides of these
metals.
This difference of combining power, the knowledge of
which is so useful to the chemist, is sometimes called
the "atomicity," "equivalence," or "quantivalence" of
the element, which may be defined to be its power of
displacing, or entering into combination with, another
element.
Those elements whose atoms are equivalent to one
atom of hydrogen are called monads; those whose atoms
can replace two atoms of H, dyads; those whose atoms
can replace three, triads; four, tetrads; five, pentads;
and six, hexads;-as in the following table:ATOMICITY OF THE COMMON ELEMENTS.
MONADS.   DYADS.   TRIADS. TETRADS.   PENTADS.  HEXADS.
Hydrogen. Oxygen.   Boron. Carbon.   Nitrogen.  Sulphur.
- ----- ---    --  Silicon.  Phosphorus. Selenium.
Chlorine.  Barium.  Gold.
Bromine.  Strontium.       Tin.      Arsenic.   Chromium.
Iodine.  Calcium.          Aluminium. Antimony.  Manganese.
Fluorine.  Magnesium.      Platinum.  Bismuth.  Iron.
Zinc.            Palladium.   -       Cobalt.
Potassium. Cadmium.        Lead.                Nickel.
Sodium.  Mercury.
Lithium.  Copper.
Thallium.
Silver.
The atomicity of an element is indicated when symbols only are used,
by using dashes, or Roman numerals, on the right of the symbol, as in the
"Table of Most Important Elements."




62             PRACTICAL CHEMISTRY.
The atomicity of elements, and'their modes of combining with others, may also be represented by their
symbols having lines, bonds, or dashes standing out from
them, at the other ends of which the symbols of the combining elements may be written. These are the graphic
formule of Dr Frankland. Thus the atoms of H and C1
would be represented as having one bond, Zn and O with
two, B and Au with three, C and Pt withfour, P and N
withfive, and S with six dashes.
Gold,  - Au-                 \/
Chlorine,  C1-                     Phosphorus,- PZinc,   -Zn -    Carbon, -    -    Sulphur,  -S~~I           /'\
Potassic, magnesic, and auric chlorides would be represented thus:-                      Cl
Cl-K; C1-Mg-C1; Cl-Au-C1
Zincic oxide, Zn = 0
Atoms when isolated unite with other atoms, and form
themselves into molecules. A molecule must have all
its bonds engaged, that is, it cannot combine with any
substance without altering the arrangement of the atoms.
Hence, there must always be an even number of bonds
in the molecule of any element or in any compound.
Some elements with an even number of bonds can
exist as monatomic molecules, their own bonds satisfying
each other, as
Mercury Hg      Zinc -Zn-. and Cadmium Cd
/....     i.... —         /...
The molecules of most elements, however, are diatomic,
that is, are made up of two atoms, as
H-H         C1 —C1      0 = 0    N= N
Oxygen in the state of OZONE has three atoms in its
0-0
molecule, it is triatomic, \0/; phosphorus and arsenic are




COMBINATION BY VOLUME AND WEIGHT.        63
tetratomic; and sulphur is hexatomic, or has six atoms in
its molecule.
A pair of the bonds of an element may
unite together or become latent.  Thus       C
nitrogen, which has five bonds, as in    H- N - t
ammonic chloride (NH4C1), may have three    / \
bonds active and two latent, as in ammonia  H H
gas; or it may have only one active and      H
four latent. Hence the terms " absolute,"     I
"latent," and " active," atomicity.      H- N -H
The bonds always diminish or increase     / 
in pairs. The element having the greatest
number of bonds in a compound is usually placed first, and
is printed in thicktype inthe following pages, asNHa, OH2.
Some elements in compounds group themselves together and act as elements.  These atom groups are
called compound radicals, as hydroxyl.  Ho2 the molecule, and Ho the atom or semi-molecule; as, in sulphuric
or nitric acids, SO2Ho2 and NOHo, the figure on the
right multiplying the group (2 of H and 2 of 0), the
small o being written for quickness, and to show that it
is part of the group. The same atom fixing power belongs to them as to the elements, they are hence monads,
dyads, triads, etc., replacing and displacing one another
just as elements do. Hydroxyl Ho is a monad radical,
whilst the dyad radical zincoxyl is represented by Zno",
with the two dashes to mark its atomicity. Zno", or its
analogues, will replace Ho2 in compounds, or Ko2, etc.
53. Nomenclature.-The names given to the elements
are for the most part arbitrary, but are easily remembered.
In binary compounds, that is those consisting of two
elements, the root of the name of the electro-positive or
basylous element comes first, being made to end in ic,
followed by the root of the chlorous or electro-negative
element, with the ending ide, thus:Sodium and chlorine form Sodic chloride NaCl
Magnesium and oxygen form Magnesie oxide MgO.
The same with sulphides, bromides, iodides, nitrides, etc.




64              PRACTICAL CHEMISTRY.
If there be two compounds of the same elements, that
which has the smaller quantity of the chlorous element
takes thetermination ous to first name, ic beingused forthat
which has the larger quantity of the chlorous element, as
Mercurous chloride, Hg2C1,.  Ferrous sulphide, FeS.
Mercuric chloride,  HgCl2.  Ferric sulphide, Fe2S3.
Sometimes the prefixes hypo (under), and per (for
hyper, more), are used to indicate a smaller or greater
quantity of the chlorous element. In a few instances
prefixes are used, indicating the number of atoms of
each element, as triferric, tetroxide, Fe304, containing
three atoms of iron and four atoms of oxygen.
Anhydrides are binary compounds, containing oxygen,
which are converted into acids on the addition of water.
Sulphurous anhydride, SO, gives sulphurous acid, SOHo,.
Phosphoric anhydride, P205, gives phosphoric acid, POHo3.
54. Acids are compounds containing one or more atoms
of hydrogen, which can be replaced by a metal or metallic
radical, forming two kinds of salts. Examples of such
combinations with metals, oxides, and hydrates, will be
found throughout the book.
Thus, hydrochloric acid or hydric chloride, HC1, when
added to a metal, has its H exchanged for an equivalent
of that metal, forming what has been called a haloid salt,
as sodic, zincic, boric, and platinic chlorides, NaCl, ZnCl2,
BC13, PtCl4, which are binary compounds.
Acids containing oxygen form a class of salts called
oxy-salts, which are ternary compounds, or contain three
elements. Thus, sulphuric acid, S02Ho2, added to zinc,
forms zincic sulphate, SO2Zno", wherethe radical hydroxyl,
Ho2, is exchanged for zincoxyl, Zno".    Those acids
whose names end in ic form salts ending in ate; those
ending in ous form salts ending in ite.
Acids are either monobasic, dibasic, tribasic, or tetrabasic, as they have one or more atoms of replaceable
hydrogen or hydroxyl, the term polybasic being frequently
used for all but the first,




HYDROGEN.                   65
Nitric acid, NOHo (Monobasic), on0ly on  class of salts
N02Nao, N02Ago.
Sulphuric acid, SOHo, (Dibasic), two classes, S02Nao2, or
SO,2Zno"; and SO2Ho-oNao.
Phosphoric acid, POHo, (Tribasic), S three classes, PONao,
PoloNao2, PoHo2Nao.
The use of symbolic and graphic formulae enables the
student to express the changes which take place in
chemical actions by Equations.  Thus, when hydrochloric acid was passed over heated potassium in the
bulb-tube in Exp. 4, Chap. V., the reactions could
be expressed in equations, graphically or symbolically,
thus:Graphic equation: H-C  + K-K=   - C1 + H - H
Hf _0-Cl+    = K      - K l
Symbolic equation: 2HC1 +.K2= 2KC1 + H2
Where the two molecules of HC1, and one molecule or
two atoms of potassium on the left, are represented by the
same number of atoms of the elements on the right of the
sign = which show the change that has taken place.
Abundant instances of chemical equations will be given
throughout the book.
CHAPTER VIII.
HYDROGEN H'.
55. WE shall now take up the study of certain typical elements, and their most important compounds, and for
this purpose we shall commence with the monad element,
hydrogen.
It will be recollected that we obtained this gas from
hydrochloric acid (HC1), water OH2, and ammonia
NH,, which were decomposed by the alkali metals,
E




66               PRACTICAL CHEMISTRY.
potassium  (K), and sodium    (Na), on account of theaffinity of these metals for the other constituent in these
compounds.
Now the metals zinc, iron, and aluminium, have a
great affinity for chlorine, and are able, at ordinary temperatures, to decompose a solution of hydrochloric acid
with evolution of hydrogen.
Exp. 1. Put a few grains of granulated zinc into a test-tube, and
pour some common hydrochloric acid upon it; violent chemical
action will take place, which increases on the addition of water.
Hydrogen will be evolved, and will inflame on a light being applied to the mouth of the tube, whilst zincic chloride will be
formed and dissolve in the water, from which it can be recovered
by evaporation.
Zinc being a dyad,* an atom of the metal replaces two
atoms of hydrogen, thus requiring two atoms of chlorine
to combine with to form zincic chloride, the reactions
being shown by the following equations:Graphic:   -Cl + Zn-Cl- Zn- C1 + H- H
Symbolic: 2 HCl + Zn = Zn C12 + H2
Iron and zinc are scarcely acted upon by concentrated
sulphuric acid (common oil of vitroil), but are violently
attacked when water is added, and dissolve with evolution of hydrogen.
Exp. 2. Pour some strong sulphuric acid on some scraps of zinc
in a test-tube, little or no chemical action will take place. Add
some water, the action will become violent, and hydrogen will be
evolved.
Whenee comes the hydrogen? Not from the zinc certainly, for that is an element; not from the water, for
water is not decomposed by zinc alone. It must therefore have come from the acid.    Now sulphuric acid is
made up of three elements, sulphur, oxygen, and hydrogen; or, according to Dr Frankland's view, of two radicals, SO2 and Ho2 (hydroxyl), its formula being H2 SO4,
* Zinc is also a monatonic molecule, hence the single atom can
be used. Two atoms of all other elements except Zn, Hg, and Cd,
must be used in equations, that is not less than a molecule, or
K2, Na2, H2, etc.




HYDROGEN.                     67
or, according to Dr Frankland's notation, SO2Ho2.   In
the former case, the atom of zinc is supposed to replace
the two atoms ofH, as in the decomposition of hydrochloric
acid.  In the latter, according to Dr Frankland's view,
a new body is formed, zincoxyl (Zno" a dyad radical),
which displaces the two atoms or molecule of hydroxyl
(Ho2) in the sulphuric acid, as in the following equations:0                     0
II                    II
Graphic; 0= S - 0 - H+Zn=       = S - 0
0                     0 - Zn
I                Zincic Sulphate.
Sulphuric Acid.
Symbolic: SO2Ho2 + Zn = S02 Zno" + H2
The water is required to dissolve the zincic sulphate as
fast as it is formed, as this substance covers the metal
directly, and prevents the further decomposition of the
acid before water is added. In the case of iron, the sulphate interferes with the action considerably.
56. Now, let us examine the properties of this gas
more fully.  For this purpose we shall require several
jars, and we may use either HC1 or SO2Ho2, and
Zn or (Fe). Hydrochloric acid is, however, preferable
to sulphuric, and zinc to iron; the hydrogen thus obtained being purer and more rapidly evolved.
Exp. 3. Into a two-necked Woulff's bottle put some granulated
zinc, and just cover it with water. Fit the bottle with a thistleheaded funnel and delivery-tube.  Stop the delivery-tube with
the finger, and blow through the funnel to see if it be air-tight.
If considerable resistance is felt, and the air rushes out violently
from the delivery-tube when the finger is taken away, the fittings
may be considered sound. If, however, the air whistles through
somewhere, the apparatus is not safe, the fault must be found
and rectified before proceeding, and only then may the student proceed safely.
Note.-So many explosions are produced for want of attention to
these points by young chemists, that the author must be excused




68                PRACTICAL CHEMISTRY.
if he has been too prolix. Hydrogen is not an explosive gas, but
it is so if mixed with air.
Fill a pneumatic trough so that the water comes just above
the shelf. Fill the jars with
water in the trough and invert them-taking care they
are quite full, standing two
on the shelves over the holes.
iP InorHave some earthenware trays,
small plates, or saucers ready,
andgreasedglass plates. Arrange the gas generating bottle
so that the delivery-tube can
be brought under the funnels
it — t llhe- air ~.in the shelf, as in the fig.
Have also a small wax taper
Fig. 22g.  B   fixed to a wire ready to light
when wanted.
Pour some hydrochloric acid down the thistle-funnel, air will
rush out of the delivery-tube and displace the water in the bottle.
A violent effervescence will take place, and hydrogen gas mixed
with the air in the bottle will pass over.  Tke first two or three jars
of this mixture must therefore be thrown away.  After a short
time, fill a test-tube with water, invert it over the hole in the
shelf and fill it with gas. Bring it to a light, which should be
burning far enough away from the generating flask. If it inflames
with a pop, air is still mixed with the gas. Try another, and if
necessary, a third test-tube, till the hydrogen burns with a pale,
lambent flame, descending quietly into the tube. Then, and not
till then, collect a jar of the gas, and when full, insert a tray or
plate under it and remove it out of the way, putting another in its
place. The water in the tray will prevent the escape of the gas.
Cover others with greased glass plates.
If necessary, pour some more HC1 into the generating bottle;
but if the zinc be exhausted, the apparatus must be disconnected
to add more, and the gas must be tested again to see if it be
free from admixture with air before collecting in jars.
Having collected several cylinders or jars of the gas,
try the following —
Exp. 4. Place a cylinder of the gas on the table mouth upwards. Invert another jar, holding it with the left hand. Remove
the greased plates from both jars, and after about half-a-minute
bring a lighted taper to the first-the gas will be found to have
escaped. Bring the light to the inverted jar, and the gas will
inflame. Plunge the taper into the gas as in the figure, it will be




HYDROGEN.                       69
extinguished, but can be rekindled at the mouth of the jar.
This can be repeated till the gas is
consumed.
The hydrogen escaped from the
first jar on account of its lightness,          - 
whilst a jar for the same reason
may be kept in an inverted position
for a quarter of an hour before it          \ 
has entirely dispersed.  Its light- 
ness may be further demonstrated 
by the following experiments.
Exp. 5. Take two equal-sized
cylinders, fill one with hydrogen
and hold the other in an inverted
position with the left hand. Care- 
fully raise the jar containing the
gas mouth downwards with the right
hand, bringing it to the mouth of
the other jar. Incline it as in the
figure, and pour the gas upwards; it,    Fig. 23.
will rise on account of its levity
through the air and displace it.
Stand the jar which previously contained the gas on the table, apply a
light, the H. will be found to have
left it, if the experiment has been
well performed.- Bring the light
to the inverted jar, the gas will
inflame with a slight report on account of mixture with air. The jar
being open, no injury is likely to       Fig. 24.
arise.
Explosions are only dangerous when the gases are confined, so that when expanded by heat they cannot easily
get out. Hence bottles are not so good as cylinders for
such experiments, and thin glass vessels should not be
used.
Exp. 6. Have a jar furnished with a stop-cock or fitted with a
cork, through which passes a piece of glass tube which may be
stopped with a cork on the top till wanted. Fill the jar with
gas at a rather deep pneumatic trough, or in a pail of water. Tie
a small balloon, made of goldbeater's skin, on to the tube,. and
having done so, press the jar down in the water, the gas will be
driven in. If there is not sufficient in the jar to fill the balloon,
decant another jar into it.
When the balloon is full, tie the neck just above the tube with a




70               PRACTICAL CHEMISTRY.
long piece of fine twine, and carefully cut it away from the tul)e.
The balloon will ascend on account of the gas being lighter than
air, and remain above till hauled down.
Balloons were formerly filled with hydrogen, but are
now filled with coal gas, which, though heavier than
hydrogen, is lighter than air.
Exp. 7. If a bladder be filled with the gas, and a piece of tobaccopipe be inserted, soap bubbles may be blown with it, and will
ascend; or a piece of flexible tube, with a bit of glass tube at the
end, may be connected with the generating bottle, and answer
the same purpose.
57. Hydrogen    is  the  lightest body   known.     Its
weight, compared with air, being as 1: 14-47.      A litre
of the gas at 0~C and 760mm pressure weighs -0896 of
a gram. A litre of air would weigh nearly 14~ times
as much, or 1'3 grams nearly.
Exp. 8. Inflame another jar of hydrogen, and hold a dry glass
over it while burning; the glass will become covered with moisture. The hydrogen in this case combines with the oxygen of
the air, and forms water.
It is best to dry the gas, however, first, to prove that
water is formed by hydrogen burning in air.
Ecxp. 9. Attach a U-shaped tube, containing lumps of dried
chloride of calcium, to the tube from the generating bottle, and
adapt a piece of glass tube drawn out to a point to the further
limb.  Take   care that the apparatus is sound.  Ascertain
that all air has been driven out of the apparatus by collecting
several test-tubes of the gas and inflaming them at the lamp.
When the hydrogen burns
quietly down the tube,
light the jet; the gas will
burn with a very pale
i  i     flame, giving but little
light.  Hold a dry belljar over it, the sides will
become   covered- with
moisture,  water  being
formed.
BIB _ Gd      f xExp. 10. While the jet
-  is burning in the last
experiment, hold a wide
Fig. s25~       glass tube, about 18 inches
Fig. 25.      long, open at both ends,
over the flame, raising and lowering it at intervals; a musical note
will be produced.  A rapid current of air is drawn in, which




HYDROGEN.                       71
gives rise to a selies of explosions which follow so quickly that a
continuous sound is produced.
58. Hydrogen may be obtained from potassic or sodic
hydrate by the action of zinc. It will be remembered
that, in speaking of the action of potassium on water, it
>vas said that part of the hydrogen was expelled.   The
other part combined with the potassium (K) and oxygen
of the water to form caustic potash (OKH or KHo), thus:
201H2+ K2 = 20KH + H2
Now the hydrogen may be replaced by zinc, but in this
case one atom  of Zn will perform   the function of two
atoms of K. And, as one atom of Zn will displace two
atoms of H, two molecules of OKH must be used.
A body called potassic zinc oxide will be formed, and
dissolve in the water.
Zn + 20KH = ZnKo, + tH
Exp. 11. Make a strong solution of potash or soda (Na Ho), and
put it irito a retort, with some zinc turnings. Heat it to boiling
on a sand-bath; a gas will
be given off which may
be collected over water as
usual. Some steam will
also pass over, but this
will condense.
On applying a light to
the gas collected, it will
inflame-the gas is hydrogen.
Iron, if heated to
redness, decomposes 
water, combining with
the oxygen and liberating  hydrogen.   A
red-hot poker plunged
into water does so.              _ 
Bxp. 12. Adapt a flask,
in which steam can be               Fig. 26. 
generated, to a piece of
hard glass tube, in which some iron filings or borings have
been previously placed.  Fit a delivery-tube to this, connected
with the pneumatic trough. Heat the flask, and as the steam
passes over the iron filings, heat them to redness by a Here




72              PRACTICAL CHEMISTRY.
path's blow-pipe.. The steam will be decomposed, triferric tetroxide,
FeO04, being fornled, and hydrogen liberated. The gas may be collected as usual.
Fe3 + 40H2 = Fe30, + 4H,
A furnace is generally used for this experiment, as in
Fig. 27. Iron nails are put into a piece of gas-pipe, and
the glass tubes are cemented in. Such a furnace can be
easily made for a few shillings, and serves for many experiments. A mixture of coal and coke, or charcoal, may
be used as fuel, and the chimney can be put into the flue
of an ordinary fireplace.
Fig. 27.
The reactions which take place in Exps. 4 and. 5,
Chap. V., will now be understood:
2HC1 + Na2 = 2NaC1 + H,
2NH3 +K2 -- 2KN    + 3H2
SUMMARY.
Hydrogen is an inflammable gas, but it extinguishes
flame. It is transparent, colourless, and without taste
or smell when pure. It is the lightest body known,
standing in relation to air as 1:14'47, or -0693 of its
weight. That is, 14-47 (nearly 141) litres only weigh as
much as one litre of air at the same temperature and
pressure.
On account of its lightness, it may be poured upwards,
and may be collected by upward displacement of air.
Mixed with air or oxygen, it is explosive.  It forms ~ of
the weight of water and - of its volume.  When burnt
ir air or oxygen, water is formed.
It is very slightly soluble in water. It is an electropositive element, appearing at the negative pole, when com



CHLORINE.                    73
pounds containing it are decomposed by the electric current.
It combines with electro-negative elements, as chlorine,
oxygen, nitrogen, and carbon, to form compounds from
which it can be liberated by certain metals. It is also a
necessary constituent of all acids, and of a large number of
other compounds. It is a monad element, two atoms, H,
being replaced by one atom of a dyad element, like zinc.
CHAPTER IX.
CHLORINE C1'.
59. WE have already learned something about the properties of this gas in Chapter VI., having obtained it from
hydrochloric acid by means of the electric current. It is,
in fact, generally obtained from this source in the laboratory on account of its cheapness, the commercial acid
being obtained as a by-product in the manufacture of
carbonate of soda (washing soda) from common salt. It
may indeed be obtained from common salt, NaC1.'
The most simple way, however, of obtaining the gas is
by heating platinic chloride, the metal platinum having
but slight affinity for chlorine.
Exp. 1. Heat a few drops of the solution of platinic chloride in
a test-tube, it will decompose, a greenish-yellow pungent-smelling gas will he evolved, which bleaches a moistened litmus paper
instantly, and the metal platinum will be left in a spongy state.
PtCl4 = Pt + 2C12
Great care must be taken in experiments with chlorine,
as it is a poisonous gas, and if inhaled, unless largely
mixed with air, may produce serious effects. It irritates
and destroys the tissues of the air-tubes of the lungs,
causing violent coughing and oppression of the chest. It




74              PRACTICAL CHEMISTRY.
should not, therefore be allowed to escape into the room;
indeed, all experiments with chlorine are best carried on
under a hood connected with the flue, or where there is
a good current of air. When not being collected, the
delivery-tube should be passed into a jar containing a
solution of sodic hydrate, or milk of lime, either of which
absorbs the gas. It is advisable to have a cloth wetted
with ether or methylated spirit laid on the table, as these
liquids dissolve the gas. Ether may be inhaled also with
advantage should the gas be inhaled by accident, but
brisk exercise in the fresh air is the best restorative in
such cases.
Platinic chloride is too expensive to be used where
jars of the gas are required for experiments. Hydrochloric acid is the best source from which to obtain the
gas in any quantity.
If HC1 be heated with black oxide of manganese (manganic dioxide, MnO2), the latter exchanges its oxygen for
chlorine, manganic chloride (MnCl4) and water being
formed, the two atoms of dyad oxygen being replaced by
four atoms of monad chlorine.   The manganic chloride
formed is a very unstable compound, splittling immediately into manganous chloride (MnCl2), and setting free
half the chlorine. The reactions are therefore best shown
in two stages:
MnO02 + 4HC1 = MnCl4 + 20H2; then
MnC14 = MnCl, + C12
Exp. 2. Fit up a wide-mouthed 8-ounce flask (a Florence flask
will do), with a thistle funnel, and a delivery-tube bent twice
at right angles. Let the longer leg of the tube pass through a
cork fitted air tight into a two-necked* WoulfFs bottle, and just
dip into the water. Fit a delivery-tube to the other neck leading
to the pneumatic trough, as in Fig. 28.
* A three-necked Woulff's bottle may be used in this case, as in
making a solution of hydrochloric acid, explained in next chapter.
A straight tube is fitted to the central neck, dipping into the water,
so that air is admitted if the pressure from the generating flask
diminishes, preventing a backward rush of water. On the other
hand, if the pressure is too great, the water rises in the central
tube. Such an arrangement is called a safety tube.




CHLORINE.                        75
The latter must be filled with water as hot as the hand can bear,
as chlorine is soluble in cold water to the extent of two or three
times its volume.
Put about an ounce of finely-powdered manganic dioxide nto
the flask, pour in enough of the strongest commercial hydrochloric acid, to thoroughly wet the MnO2 by shaking it. Replacs
the cork, and arrange the apparatus, jars being filled with water
and inverted ready in the trough.
Heat the flask over a sand-bath, the chlorine will come off
rapidly, any HC1 that comes over without being decomposed being
dissolved by the water in the Woulff's bottle. Replace the first
Fig. 28.
jar, when full, by another, covering the first with a greased glass
plate, and removing it to the table.
Exap. 3. To show the solubility of chlorine, nearly fill a smallmouthed bottle with the gas, cover with the thumb and shake
well; then put the mouth of the bottle under water and remove
the thumb, more water will rush in, absorbing or dissolving the
gas. Repeat this operation several times, and a solution of the
gas will be obtained, which will do in many cases instead of the
gas itself.
At 60~ water absorbs its own bulk of C1, the solution
being of a pale yellow colour, with an astringent nauseous taste. The solution has the sp. gr. 1 008.
Chlorine being heavier than air, may be collected by
downward displacement.
Exp. 4. Adapt a delivery-tube bent twice at right angles to tle
Woulffs bottle, which must be raised on the table support or or




76               PRACTICAL CHEMISTRY.
blocks, so that the outer limb of the tube shall reach to the bottom
of the bottles or jars. A card with a hole cut in the middle, or
a notch at the side-a little larger than the tube-being put over
the jar. The gas lifts the air out on account of the difference in
density. When a litmus paper is bleached at the opening, the
jar may be considered full.
Of course by this mode there will be a slight admixture with air, but this does not matter for most experiments. The tube when removed from the jar should
be put into one containing a solution of caustic soda, as
before directed, unless others have to be filled.
The gas may be dried by passing it through calcic
chloride or a bottle containing sulphuric acid and pieces
of pumice stone or coke, neither of which combine with
the gas.
60. Chlorine is an electro-negative element, appearing
at the positive pole in the electric decomposition of HIC
and other chlorides. It acts with great intensity upon
electro-positive elements, as in the case of hydrogen
(Chap. VI., Exp. 9), combining with and' frequently
liberating them from their compounds.
Antimony, arsenic, copper, etc., burn in chlorine
spontaneously, forming chlorides.
Exp. 5. Shake some powdered antimony from the tip of a knife
into a tall jar of chlorine. It takes fire as it descends, forming
a white smoke consisting of antimonious chloride, which being
volatile makes the action more violent. Finely powdered metallic
arsenic acts in the same way. The volatilised chlorides must be
avoided, as they are very poisonous. Remove the jar under the
hood, or into a good draught immediately; or, perform the experiment there:
Sb2 + 3 C12 = Sb2C16.Exp. 6. Attach a piece of Dutch metal (imitation gold leaf,
consisting of copper and zinc) to a wire, and put it into a jar
of C1.  It will inflame, forming cupric and zincic chlorides
(CuCI2 and ZnCI2).
Exp. 7. Heat a bit of sodium in a deflagrating spoon and plunge
it into a jar of the gas.  The intense heat will volatilise the
sodic chloride or common salt (NaCl) formed, and vivid combustion will take place. If put in without being heated, it only
becomes covered with a white crust of NaCl.
Exp. 8. Put~a little of the solution of chlorine into an evaporat



CHLORINE.                      77
ing dish and put a bit of sodium in it. The metal will burn,
sodic chloride being formed, which will dissolve in the water
and give it a saline taste.
61. Chlorine combines with chlorous or electro-negative elements, but not so energetically.
Exp. 9. Put a bit of phosphorous into a deflagrating spoon and
plunge it into a jar of chlorine. It will burn spontaneously,
but not so vividly, phosphoric chloride-PC]5-being formed.
Chlorine decomposes such bodies as tallow, wax, and
paraffin, which are rich in carbon and hydrogen, combining with the latter to form  HC1, and liberating the
carbon in a finely divided state.
Exp. 10. Plunge a lighted wax taper, attached to a piece of
wire, passing through a card, as in Fig. 29. It will burn with
a lurid flame, giving off a large quantity of smoke, white fumes
of HC1 being also formed in the jar.
Exp. 11. Steep a piece of blotting paper or rag in turpentine (not French turps). It will burst into flame instantaneously,
dense volumes of smoke being evolved.
C,10H6 + 8 Cl2 = 16 HC1 + 10 C.
A jet of coal gas burns with a red smoky flame in chlorine. A jet
of hydrogen on the other hand burns with a feebly luminous flame,
white fumes of HC1 only being produced. (See Fig 30.)
Fig. 29.                        Fig. 30.
62. Chlorine decomposes colouring- matters which are
obtained from animal or vegetable substances, combining
with part of the hydrogen, forming colourless compounds.
It is thus used for bleaching calico and other fabrics.
Exp. 12. Hold a bunch of violets, a bit of turkey-red cloth, or




78                PRACTICAL CHEMISTRY.
a dry litmus paper, at the mouth of a jar of C1, the colour will
be scarcely affected.  Wet them  and they will be instantly
bleached. The colouring matters contain H, which is withdrawn
by the chlorine, and the oxygen of the air bleaches. A solution
of sulphate of indigo (sulphoindigotic acid) and ordinary writing
ink are bleached by C1, but printer's ink, which contains carbon,
is not. The solution of the gas will do for such experiments.
The use of chlorine and compounds containing it, as
deodorising agents, also depends on the fact that the
hydrogen of decomposing animal and vegetable substances combines with it to form HC1, and the substances become oxidised by the air. All disinfectants
which evolve C1 deodorise by the action of the oxygen
in the air.
Slaked lime or calcic hydrate absorbs chlorine, forming the so-called "chloride of lime," or bleaching powder.
For this purpose the lime is spread on shelves perforated
with holes in a closed chamber, into which torrents of
chlorine are sent by a pipe. The gas is absorbed to the
extent of 30 or 40 per cent., but is rapidly lost on exposure to the air.
See Reactions, in Chap. XIII.
A weak acid-even citric or tartaric-is sufficient to
liberate the chlorine from this compound. Chlorine is
even evolved by the small amount of carbonic acid gas in
the air, but it takes place more rapidly when mixed with
water, particularly if a few drops of any acid are added.
Exp. 13. Put some "chloride of lime " into a beaker, and pour
upon it a few drops of HC1 or vinegar; C1 is evolved rapidly.
Cover with a glass plate to prevent its being inhaled.
Exp. 14. Stamp a pattern on a piece of turkey-red cloth by
dipping a bit of wood into a solution of bleaching powder
("chloride of lime ").  Dip the cloth into water made sour
by some tartaric acid. The colour will be discharged only at
the stamped spots. In this way the white figures on a coloured
ground are produced in coloured handkerchiefs.
It has been seen by Exps. 7 and 8 that common
salt is a chloride of sodium.  Hence the vast stores of
rock-salt form the great natural storehouse of chlorine.
When sulphuric acid is poured upon common salt, both
are decomposed, HC1 being formed. Now, the whole




HYDROCHLORIC ACID.                  79
of the chlorine can be obtained from the HC1 at the
moment of its production (when in the nascent state) by
adding MnO2 thus:
Exp. 15. Add together in a flask 4 parts by weight of NaCI,
1 part of Mn02, 2 of sulphuric acid, and 2 of water.  Heat the
mixture; manganous sulphate, sodic sulphate, and water will
be formed, and the whole of the chlorine will be evolved:2 NaC1 + 2SOHo2 + MnO2 = SO2Mno" + SO2Nao2 +
2 0H2 + C12
Some hydrochloric acid is sure to be carried over,
however, unless the sulphuric acid be added through a
thistle funnel. It can be got rid of by making it pass
through water in a Woulffs bottle.
Question.-How much chlorine by weight (in grams) and by
measure (in cubic centimetres) can I obtain from 1 litre of
HC1, measured at 0~C and 760mm mercurial pressure.
Here 1 litre of HC1 would furnish - litre of Cl*0896 x 35-5'. *  -2-    = 1'5904 grams.
And as 1 litre = a cub. dec. I litre ='5cd or'5 of 1000
= 500 cubic centimetres.
SUMMARY.
Chlorine is 35 5 times the weight of hydrogen, and
35.5
i4 47 or 2-45 times the weight of air.  A litre of the gas
weighs -0896 x 35-5 = 3-1808 grams.
Cold water dissolves its own volume of the gas when
agitated. The gas is of a yellowish-green colour, and is
very pungent and poisonous. It forms salts with the
metals called chlorides. It is a bleaching and disinfecting agent on account of its affinity for hydrogen.  A
solution of the gas acts like the gas itself.
CHAPTER X.
HYDROCHLORIC ACID HC1.
63. THIS is a gas; its solution is known by the same name;
it is also called muriatic acid or spirits of salt, being used
in the laboratory and the arts for a variety of purposes.




80               PRACTICAL CHEMISTRY.
It has already been prepared synthetically by exploding
a mixture of equal volumes of hydrogen and chlorine.
H2 + C12 = 21HC1.
The same reaction takes place when a jet of H      is
burned in C1.
Combination of the gases H and C1 also takes place
slowly in diffused daylight, and immediately with explosion in strong or direct sunlight, or in a light rich in
chemical rays.
Exp. 1. Fill a jar, half with C1 and half with H. Cover it with a
greased glass plate, and put it in the dark, no action takes place.
Remove the jar into the daylight-not in the blaze of the sun;
slow combination takes place, HC1 being formed, which will
redden a blue litmus paper, and not bleach it unless the C1
was in excess. White fumes will appear in the jar if it or the
gas be moist.
If a small glass bulb be filled with the mixed gases, it may
be exploded in the following manner:-For safety put it into
a cigar-box turned on its side. Into a cylindrical jar filled with
nitric oxide (for preparation see Exp. 11, page 121), pour in a
few drops of bisulphide of carbon, or put a small bulb containing that liquid into the jar; shake up and break the bulb, so that
the CS2 may be spread over the sides of the jar. Place the jar
before the open box containing the bulb of mixed H and Cl.
Stand behind the box, and removing the glass plate that covers the
jar, apply a lighted taper; the mixture will burn with a blue
flame rich in chemical rays, which will cause the H and Cl in
the bulb to combine with a loud crack, breaking the glass,
white fumes being produced from the hydrochloric acid gas dissolving in the moisture of the air.
64. Hydrochloric acid is prepared by gently heating
sodic chloride (common salt) with sulphuric acid, diluted
previously with a small quantity of water. The sodic
chloride is decomposed and also the acid, one half the
hydroxyl of the latter being replaced by sodoxyl, forming
hydric sodic sulphate, which dissolves; the other half of
the hydrogen combining with the chlorine of the common
salt.
NaCl + SO2Ho = SO2HoNao + HC1.
Exp. 2. Into an 8-oz. flask fitted with a funnel and deliverytube (or a Florence flask), as in making chlorine, Fig. 28, put three
parts by weight of fused sodic chloride and five of oil of vitriol,




HYDROCHLORIC ACID.                 81
mixed with an equal quantity of water. Heat gently on a sandbath; a colourless gas will come off, which being rather heavier
than air, may be collected by displacement as in the case of chlorine.
It cannot be collected over water on account of its
great solubility, but it may be over mercury, though it
is not advisable, as the gas, which is very irritating to the
eyes, is apt to escape, and the experiment is somewhat
too difficult for a young student to manage.
Exp. 3. Collect two small cylinders of the gas, and into one jar
plunge a lighted taper; it will be extinguished. A blue litmus
paper will be turned red, showing the gas to have acid properties.
Exp. 4. Invert the second jar under  -
water, which may contain a small quantity of infusion of litmus. Remove the
greased plate, and the water will rush
violently up the jar, dissolving the gas  l:
completely, and turning the litmus red.
To perform this experiment well, the gas 
should be dried by passing through a
dessicating bottle containing sulphuric
acid, or through a tube containing chlo- 
ride of calcium (see Fig. 15, p. 46).
Should any be collected over          Fig. 31.
mercury, it must first be dried for
the latter experiment, and then a piece of ice may be
inserted under.the jar, water even in the solid form aborbing the gas.
The following experiment shows the solubility of the
gas in a striking manner:
Exp. 5. Collect a jar of dry HC1 -over mercury, and then pour
some water into the vessel. Raise the jar out of the mercury into
the water-the latter will rush up and fill the jar (Fig. 31).
A glass tube, with a stout bulb at the end, may be
used for showing the solubility of the gas. This being
filled with the dried gas, should be inserted in a little
cup of mercury, which should then be put into a vessel
of water; the tube being raised above the mercury, the
water will rush up with great violence. Water dissolves
480 times its volume of the gas, the solution being
increased by about ~ in bulk, with a specific gravity of
1'2 compared with water.
F




82              PRACTICAL CHEMISTRY.
65. Hydrochloric acid converts certain metals, metallic
oxides, and hydrates, into salts called chlorides. Indeed,
it may be considered as a salt of hydrogen, and is hence
frequently called hydric chloride. The salts derived
from it by the substitution of a metal for hydrogen being
called haloid salts, to distinguish them from those containing oxygen.
Thus, Zn, Fe, Ig, and Al, are dissolved by Hcl,
liberating hydrogen and forming chlorides. And here
the knowledge of atomicity becomes valuable, enabling
the student to know how many atoms of hydrogen can
be replaced by the metal, and hence how many molecules
of the acid are required. The dash on the left of the
symbol for aluminium shows the latent bond.
Mg2" + 4HC1 = 2MgCL, + 2H2'AL"'C1, 
iAl2'" + 6HC1 ='Al"'0Cl + 3H2
The dried gas passed over the metals potassium and
sodium in Chap. V. acted in the same manner (see also
Chaps. VII. and VIII.).
Some metals are but slightly attacked by this acid
when cold, as Pb, Ag, Cu, Bi, Sb, and the metal tin only
with difficulty even in boiling acid..Exp. 6. Put a little cupric oxide (black oxide of copper) into a
test-tube, and pour upon it some strong HC1. Gently heat it, a
green solution of cupric chloride will be the result. The dried
gas may be passed over it in a hard glass tube heated by a Bunsen
flame, with the same result.
CuO + 2HC1 = CuCl2 + OH,
The oxides of zinc and mercury act in a similar
manner.
Exp. 7. Make a solution of sodic or potassic hydrate in a beaker,
and add a solution of HC1 drop by drop to it till it neither turns
a reddened litmus paper blue, nor a blue one red. The solution
will be neutral and have a saline taste. If some of it be evaporated slowly, crystals of sodic or potassic chloride will be formed.
NaHo + HC1 = Na01 + OH,
Baric and calcic chlorides may be prepared from their
corresponding hydrates in the same manner; water being
a secondary product in all cases.
CaHo2 + 2HC1 = CaC]2 + 20H2




HYDROCIILORIC ACID.             83
All chlorides but those of Pb, Ag, and Hg, are soluble
in water, the former of these being soluble in boiling
water, and AgOl in ammonia.
The test for chlorides in solution is argentic nitrate
No2Ago (nitrate of silver).  The strongest solution
contains about 40 per cent. of acid. If this be heated,
the gas is liberated till the density becomes 1 1, when
both acid and water distil over at 106~0 unchanged. A
weaker acid loses water till its density is 1 1 (containing
only about 20 per cent. of gas), and then at 106~C
behaves as above. The strength of a solution can be
tested by the hydrometer.
To prepare a solution of the gas for laboratory purposes, it is passed through a series of three or four Woulff's
bottles half-filled with distilled water. The delivery
tubes must only just touch the surface of the water, as
the gas is absorbed with great avidity, and the bottles
must be furnished with safety tubes. (See preparation of
Chlorine.)
The first bottle retains any sodic chloride or sulphuric
acid that might have been carried over mechanically,
and the water in the other bottles become successively
saturated with the gas.
Cast-iron cylinders lined with fire-clay heated in a
furnace, and earthenware bottles, are used in its preparation on the large scale. The crude acid obtained in this
way is often yellow from the iron of the retorts in the
form of ferric chloride; arsenic, as arsenious chloride, is
also present sometimes from the impure sulphuric acid
used. If SO2Ho2 be present, the addition of a solution
of baric chloride produces a white turbidity (a precipitate
=pp.). Arsenic gives a yellow colouration or pp. with
sulphuretted hydrogen; and the addition of a solution of
ferrocyanide of potassium gives a pp. of prussian blue if
ferric chloride be present.  When pure, the solution
should be perfectly colourless, and give no pp. with the
above reagents.
Hydrochloric, acid is obtained as a by-product in the




84             PRACTICAL CHEMISTRY.
manufacture of carbonate of soda from common salt.
The sodic chloride is put into a reverberatory furnace,
and oil of vitriol is poured upon it through a funnel
opening in the roof. The flames play over a bridge upon
the materials, and in consequence of the great heat
obtained, the whole of the hydrogen of the acid combines with the chlorine, or the whole of the hydroxyl
is exchanged for sodoxyl, forming the neutral sulphate
of soda. In consequence of this, one half the quantity
of acid only has to be used, as in the following equation:
2 NaCI + SO2Ho2 = SO2Nao2 + 2HC1
Formerly, torrents of the gas escaped as a waste product
from the chimneys of the manufactories in the North of
England, poisoning the neighbourhoods where they were
situated.
It is now conveyed into towers filled with coke, down
which a stream of water constantly trickles and dissolves
the gas. The towers are connected with the chimney to
produce a draught. A solution is obtained in this way,
which is used in the preparation of chlorine in the
manufacture of bleaching powder ("chloride of lime ").
See Chap. XIII.
CHAPTER XI.
OXYGEN 0".
66. OXYGEN is a dyad element. It is very abundant
in nature, forming - of the weight of water. It forms
also } of the volume of the atmosphere, the remainder
being principally nitrogen, with which it forms a mechanical mixture.  It forms also about ~ of the solid
crust of the globe, being found as a constituent of such
minerals as lime, quartz, clay, as well as in combination
with various metals as oxides.
It has already been obtained from water by the action
of the electric current (see Chap. VI.). It can also




OXYGEN.                    85
be obtained by chemical means as stated in Exp. 10 of
the present chapter.
It may be abstracted from the air by keeping mercury
near its boiling point for several hours. The red powder
thus obtained when heated to about 400~ C gives up its
oxygen again, so that this is a means of obtaining oxygen
from air. A molecule of HgO (mercuric oxide), or 216
parts by weight, yielding 200 parts by weight of mercury, and 16 of oxygen, which are the relative weights of
the atoms of these elements. Or, to express the decomposition by a molecular equation, so that a molecule of
oxygen should be liberated,
2 HgO = Hg2 + 02
Exp. 1. Heat a small quantity of mercuric oxide in a test-tube or
bit of hard glass in the Bunsen flame. Adapt a delivery-tube
so that the gas may be collected at the pneumatic trough. A
mirror will appear round the side of the tube, which will be found
to consist of globules of metallic mercury, and a colourless gas
will come off which may be collected in a test-tube as usual.
Plunge a glowing splinter into the gas, it will be rekindled.
The gas is oxygen.
Argentic oxide may be used, but it requires greater
heat to decompose it-that of a Herepath's blow-pipe for
instance. Oxygen will be given off and a button of silver
will be left.
2 OAg2 = 2 Ag2 + 02
Both the latter methods are, however, expensive, and
therefore other materials must be resorted to where any
quantity of the gas is required.
The mineral pyrolusite, black or dioxide of manganese,
used in obtaining chlorine from HCI, Chap. IX., gives up
one-third of its oxygen when heated, but the experiment
requires to be done in an iron bottle. Another compound
of manganese and oxygen being produced, similar to that
of iron, by the passage of steam over it as in Exp. 12,
Chap. VIII.  It is called the trimanganic tetroxide.
3 MnO2 = Mn3 04 + 02
If it be heated with sulphuric acid, it gives up one-half
its oxygen, and sulphate of manganese is formed.
MniO + SOlHo2 = SO.Mno" + 02 + OHa




86              PRACTICAL CHEMIISTRY.
Exp. 2. Put a small quantity of dry powdered manganic dioxide
into a test-tube, and pour sufficient strong sulphuric acid on it
to thoroughly wet it. Heat cautiously. Oxygen gas will come off;
which may be tested by a glowing splint.
The salt called potassic chlorate (chlorate of potash) is
the most convenient source of oxygen in the laboratory.
Some of it should be first put into an evaporating dish
and heated. The salt will melt, and the water held in
the crystals will be given up.  It hardens on cooling,
and should then be pulveiised in a mortar.
It may be either used alone, or it may be mixed with
about one-third of its weight
of manganic or cupric oxides
(powdered glass or sand will
do); the gas comes off at a
lower temperature, but is
not quite so pure. The manganic dioxide appears to be
unaltered at the end of the experiment. It seems to attract
more oxygen from the chlorate, with which it cannot howFig. 3~1-a.       ever combine, and thusassists
the repulsive action of heat.
The three atoms of oyygen in the potassic chlorate are
all given off in either case, as one of them  cannot exist
alone, hence two molecules are used in the graphic and
symbolic equations below.
Graphic   K-O-O-O —C1}
Heited    OC0
to o —0)
(OC1
Symbolic (better method) 2 0  = 2 KC1 + 3 O2
(OK
Potassic perchlorate is, however, first formed (see
Chap. XIII.), and this again is decomposed into potassic
chloride and oxygen.




OXYGEN.                      87
(Potassic-Chlorate) 2 Cl02Ko = ClKo + KC1 + 0,
Then Cl03Ko = KC1 + 2 02
Exp. 3. Put some of the mixture (sold as oxygen mixture),
which has been previously dried, into a dry Florence flask fitted
with a delivery-tube for collecting the gas in jars over water in the
pneumatic trough (Fig. 31-a).
The residue left in the flask should be allowed to cool, and
afterwards water should be poured in and agitated. The potassic
chloride will dissolve, and the whole should be thrown on to a
large filter. The filtrate will contain the KC1, which is of no service, but the black residue on the filter MnO2, may be well dried
and used again.
For storing large quantities of
such gases as oxygen and hydrogen a gas-holder is very useful.
One called Pepy's is shown in
Fig. 32. 
It consists of two cylinders, A 
and B, made of zinc, connected
with each other by two tubes. 
One of these, a, passes nearly to 
the bottom of the lower cylin-           a
der, the other b, just through
its upper part.  There is also a
third bent tube c passing out of 
the top of the lower cylinder, 
to which a flexible tube can be
attached. These are all furnished  d
with stopcocks.  A tube passes 
out obliquely from  the bottom
of the lower cylinder, which can
be closed by a screw plug p.  To
use the gas-holder, it is placed
over a sink, or tub, as in Fig. 32.
The plug   is screwed in, the
taps of a, b, and c are opened,        Fig. 32
water is poured into the upper cylinder or funnel A,
and runs down a and b, filling the lower cylinder B, the
air coming out at c, and the height of the water being
shown by the gauge d.




88               PRACTICAL CHEMISTRY.
When the lower cylinder is filled with water, the
stopcocks a, b, and c are closed, and the screw plug taken
out, the water being kept in the cylinder by the pressure
of the atmosphere. The gas delivery-tube is inserted
at p, and the gas rises to the top of B, driving out the
water at p into the tub.
When full of gas, the plug is screwed in, and water
poured into the funnel A.   The stopcock b is opened to
allow water to flow into B to press out the gas. Jars of
gas may be filled at A as in a pneumatic trough by opening the stopcock b, or a flexible tube may be attached to
c. Water must of course be continually poured into A
to keep up the pressure in B, and the latter will be full of
water as shown by d when all the gas has been used.
Havidg collected several jars of the gas either from the
gas-holder or at the pneumatic trough in the usual way,
try the following experiments:Exp. 4. Plunge a piece of small wax taper
stuck on the end of a wire passing through
a card into a jar of oxygen. It will burn
very fiercely till all is consumed. Cover
XHmB  ~ the jar with a glass plate for further examination.
ExI. 5. Wind a piece of wire passed
through a card round a piece of charcoal,
taken from the bark. Heat it to redness
_  in the Bunsen flame, and plunge it into
a wide gas jar; it will burn with beautiful
scintillations, a colourless gas being the
result. Cover this and put it aside for
further examination also.
Fig. 33.       Exp. 6. Put a small piece of sulphur
into a deflagrating spoon run through a
bit of card or attached to a brass flange. Melt the sulphur and
it will inflame. Plunge it into another bell jar of oxygen. It
will burn with a beautiful blue flame, producing a colourless gas
with a pungent odour. Cover and put aside.
Exp. 7. Inflame a small chip of phosphorus in a deflagrating
ladle, and plunge into a bell-jar of oxygen. It will burn brilliantly,
a dense white vapour being formed, which itself takes fire, and
makes the light of dazzling brilliancy. Cover and put aside.
Exp. 8. Make a spiral of very fine iron wire by coiling it round
a pencil. Pass it through a card. Put a bit of German tinder on




OXYGtE.                     89
the end of it and light it, or dip it into melted sulphur. Plunge
it into a bottle of the gas. Beautiful scintillations will be thrown
off, consisting of the iron combined with oxygen, which often fuse
into and crack the glass, hence a little water should be left in the
bottom. A piece of watch-spring, first heated to redness to soften
it, and then plunged in quickly whilst red-hot, may be substituted
for the iron wire.
Exp. 9. Melt a bit of sodium in the deflagrating ladle, which
should first be cleaned and dried. It will take fire, and when
plunged into oxygen, will burn more brilliantly, with an intensely
yellow flame.
Turning to the results of these experiments, we find:
Exps. 4 and 5. A colourless gas in both cases. Test
with a lighted paper, the gas will extinguish it. Pour in
some lime-water to each, it will be turned milky. The
result of burning the taper or charcoal in oxygen was to
produce a gas called carbonic acid gas, CO2, which combines with the lime, and forms chalk or carbonate of lime
(calcic carbonate, COCao").
Exp. 6. Put into this jar a moistened blue litmus
paper, it will be turned red, the gas formed by the combination of sulphur and oxygen having.acid properties.
It is called sulphurous anhydride, SO2.
Exp. 7.. The white vapour will be found to have dissolved in the water on the sides of the jar.  A blue litmus paper in this instance too will be reddened.  The
white substance formed was phosphoric anhydride, P20p,
which, dissolved in water, formed phosphoric acid.
P205 + 30H = 3POHo3
In Exps. 8 and 9, the metals, iron and sodium, combined with oxygen, forming two of a class of solid bodies
without acid properties, called oxides. In the first case,
the triferric tetroxide (magnetic oxide of iron), FeoO4,
and in the second, sodic oxide, Na2O, were produced.
67. Many other metals, when exposed to air or oxygen,
are converted into oxides, or, in other words, rust. Zinc
and iron do so at the ordinary temperature, forming ZnO
and Fe2O, (sesquioxide of iron); copper does so at a red
heat; whilst gold and platinum do not oxidise at the
most intense heat.




90              PRACTICAL CHEMISTRY.
A stream of oxygen from the gas-holder, or a bladder
filled with the gas, in which a tobacco pipe has been
inserted, made to play upon a piece of watch-spring
whilst ignited at the Bunsen flame, gives rise to a
brilliant combustion. Such effects, however, are usually
obtained by the oxyhydrogen blow-pipe, and are more
fitted for the lecture table. A stream of oxygen is
made to mix beforehand with a stream of hydrogen
or coal gas, and the two are burned at a jet, a very
small but very hot flame being the result, in which
case, iron, and even platinum, can be melted, the former
with beautiful scintillations, producing FeO04; the latter,
however, being unchanged on cooling. The mixed gases
made to impinge on a cylinder of lime give rise to the
intense lime-light.
68. Oxygen may be obtained from water, through the
agency of chlorine, on account of the great affinity of
the hydrogen for chlorine.  When steam    and chlorine
are passed through a porcelain tube heated to redness in
a furnace, HCO is formed, and oxygen is set free, as seen
in the annexed figure.
Fig. 34.
Exp. 10. Arrange a flask for generating chlorine, as in Chap. IX.,
Exp. 2. Let the delivery-tube from this pass into the water of
a second flask, in which steam is being generated (Fig. 34).
The moist chlorine should pass through a Woulff's bottle, where
any superfluous water may condense, to prevent the cracking of
the porcelain tube. The hydrogen will combine with the chlorine
in the red-hot tube, and the hydrochloric acid formed will be
absorbed by the water in the pneumatic trough, and the oxygen
may be collected in a receiver.
Oxygen is taken away, or, in other words, de-oxidation




OXYGEN.                      91
or reduction takes place, when a stream of hydrogen from
a generating flask or a gas-holder is passed over heated
cupric oxide. The experiment may be performed by
putting some of the dried CuO in a hard glass tube, and
heating with the Bunsen flame or Herepath's blow-pipe.
The test for oxygen is nitric oxide.
Exp. 11. Pass bubbles of nitric oxide (prepared in the way described in Exp. 12, Chap. XVII.) into oxygen. Red fumes are
produced.
69. Ozone is a modification of oxygen, first discovered
by Schonbein, and so named by him from its odour. The
peculiar smell of the air near an electric machine in
action, or during a thunderstorm, is due to a part of the
oxygen being converted into ozone.     It is condensed
oxygen, three atoms of oxygen being squeezed into the
space of two to form the molecule.
Exp. 12. Put a stick of phosphorus into a bottle containing a
little water, and let it remain for some hours. Ozone will be
produced. Pass a strip of paper through some starch-paste, and
then through a solution of potassic iodide. Dip it into the jar,
the iodine will be set free, and colour the starch-paper blue.
6KI + 0, + 30H2 = 60KH + 312
Exp. 13. Pour some strong sulphuric acid into a beaker containing a solution of permanganate of potash. Oxygen, in the state
of ozone, will be immediately set free. Apply the starch-paper
test, as before.
In the electric decomposition of water, the oxygen is
in the state of ozone, and it may be readily obtained by
the electrolysis of dilute sulphuric acid and chromic acid.
It has also been obtained, by Siemens, by an induction
arrangement.
Ozone is a powerful oxidising agent, silver and mercury are corroded by it at the ordinary temperature,
and so are substances like cork and caoutchouc. It is
insoluble in water, but it is completely absorbed by oil
of turpentine. It is decomposed slowly at 100~0, and
rapidly at 290~C, returning to its former volume.
The starch-test named above is not, however, very reliable, as strong acids act in the same manner:4KI + 4HC1 = 4HI + 4KC1
and 4HI + 02   = 20H2+ 21,




92              PRACTICAL CHEMISTRY.
Hydrochloric and sulphuric acids are generally contained in the air of towns; country air, and especially
that near the sea, has, however, the same effect, liberating
iodine from the iodized starch-paper, and such air cannot
be supposed to contain these gases.
SUMMARY.
Oxygen is colourless, transparent, inodorous, and
tasteless. It is rather more soluble in water than hydrogen, at 0~0 it dissolves about 4 per cent. of the gas.
It is from the oxygen dissolved in water that fishes
obtain the means of aerating their blood. It enters into
combination with a large number of bodies producing
oxidation, in the case of the metals forming a class of
bodies called oxides. It is the source of combustion in
air, of which it forms~ of the volume. It is rather heavier
than air, being as 1'1056 to 1, and 16 times the weight of
H-a litre weighing -0896 x 16, or 1-4436 grams. It is
usually obtained from manganic oxide or chlorate of
potash. The former gives up one-third of its oxygen by
heat alone, and one-half when heated with sulphuric acid.
Potassic chlorate gives up all its oxygen when heated.
It is well for the student to practise himself with calculations on the quantity of materials required to produce a certain volume of gas, to find the weight of such
volumes, and of the secondary products. Examples of
these are given below, and a few others will be given
hereafter.
1. What quantity of oxygen by weight, and also by volume, can
be obtained by the decomposition of 100 grams of potassic chlorate,
Cl12Ko (KC103)?
Here a molecule of KC10 would weigh 39 +355+ 48 (16 x 3)
=122'5, which would furnish 48 parts by weight of oxygen.
Hence, to find how much 100 grams would produce:
As 1225: 100:: 48;
or, 10x48 - 4800 + 122'5 = 39-18 grams.
Now, a litre of oxygen weighs'0896 gram x 16 or 1-4336 grams
Hence, if we divide the weight of oxygen produced by a given




OXYGEN COMPOUNDS.                   93
weight of KC10s, by the weight of a litre, it will give the volume
in litres.
i.e., 39'18 + 1-4336 = 27-32 litres.
2. How much zincic oxide, ZnO, can be obtained by the oxidation of 100 grams of zinc?
Here the atomic weight of zinc being 65, and oxygen 16, the
molecule of ZnO would weigh 65+16, or 81.
Then, as 65:100::81;
or, 81 x 100  8100 + 65 = 124-6 grams.'65
3. A stream of dry hydrogen being passed over 100 grams of
cupric oxide (CuO) heated to redness in a hard glass tube, how
much metallic copper would be left, and what weight of water
would be formed?
CuO + H2 = OH2 + Cu.
That is, a molecule of CuO and a molecule of hydrogen would
produce a molecule of water and leave an atom of Cu-i.e.,
63'5+ 16, or 79'5 CuO and 2H = 16 + 2 (or 18) of water + 63 5 Cu.
Hence as 79'5:100:: 63-5: 79'87 copper.
And as 79-5:100::18: 22-64 water.
4. What weight and volume of carbonic acid gas would be produced by burning 5 grams of carbon in oxygen gas?
In this case, one atom of C weighing 12 combines with two
atoms of 0 weighing 32, producing a molecule of CO2 weighing 44.
This molecule is two volumes. Hence, 1 volume=22; and in
grams, 1 litre would weigh'0896 x 22, or 1-9712 grains. Hence to
find the weight.
As 12:5:: 44, or 5- of 44 = 18'3 grams.
And, as above, 18'3 = 9 3 litres of CO2.
P~9712
CHAPTER XII.
OXYGEN COMPOUNDS WITH HYDROGEN, WATER, AND HYDROXYL.
70. OXYGEN forms two compounds with hydrogen; water,
and hydroxyl, their graphic and symbolic formulse being
given below:
Water, H-O-H or OH2
Hydroxyl, H-O-O-H or O         or Ho  or H202
IOHro       OHO




94               PRACTICAL CHEMISTRY.
71. Water is very widely diffused. It always exists in
the air in an invisible state, and gives the blue appearance to the sky, and becomes visible in the form of
clouds. It forms a constituent of all animal and vegetable substances, and of many minerals. It is also formed
in a variety of chemical processes as a secondary product.
The composition of water was first determined by
Cavendish, who exploded a mixture of two volumes of
hydrogen with one of oxygen in a stout glass tube by
means of the electric spark, watery vapour being the
result, which condensed on the sides of the tube. A
more exact method, by which the resulting volume can
be ascertained, is to enclose a stout tube containing the
mixture in a jacket or outer tube in which the vapour
of boiling analine is conveyed.   This prevents the resulting water gas from condensing, and it is thus found
to contract to two-thirds the original volume.
1 volume of oxygen   or by weight 0 = 16
2 volumes of hydrogen,,      H=   2
= 2 volumes of water gas      OH = 18
Bxp. 1. Fill a eudiometer with mercury, and let it rest on a
caoutchouc pad in a trough of mereury, supporting it by the
wooden vice, Fig. 7, or a clip attached to the retort stand. Introduce 180 c.c. of hydrogen, and afterwards 90 c.c. of oxygen
(never more than about half fill the eudiometer).  Grasp it
firmly by the hand, pressing it down upon the india-rubber pad,
and pass a spark through the mixture by means of an induction
coil or Leyden jar. A flash will pass through the mixture, and
sudden expansion will first take place from the heat produced by
the combination. When cool, the gas will be found to occupy
180 c.c., showing that 3 vols. have contracted to 2. The gas
will, however, soon condense on the sides of the tube, and the
mercury will rise.
hi the bent eudiometer the thumb is held at the open end,
and acts as a buffer.
The composition of water may be determined by taking
any quantity of each gas, as in the following example:
Introduced 8-5 c.c. of oxygen, then 19'9 c.c., or rather
more than double the volume of hydrogen. This gave




OXYGEN COMPOUNDS.               95
28-4 c.c. Exploded and allowed to condense, 2-9 c.c.
remained, which proved to be hydrogen.  Then 28-4 -.
2'9 = 255, of which 1 was O and 2 H.  Hence, 17 c.c.
Fig. 35.
of hydrogen, combined with 8 5 c.c. of oxygen, or in the
proportion of 2 to 1.
From its composition by weight the percentage composition of water can easily be found, thus:
As 18: 100: 2: 1111 of hydrogen.
And 18: 100: 16: 88 99 of oxygen.
Its decomposition by the electric current has been
explained in Chap. VI., and its composition has been
determined also by the experiments in Chaps. V. and VI.
Water is formed when a jet of hydrogen is burnt in
oxygen or in air. It
is also formed with
other products when
tallow, wax, gas, etc.,
are burnt, and also
in the combustion of
coal.
Exp. 2. Bring the
flame of a spirit lamp
under a funnel which
leads into a glass tubei. 
surrounded by another tube containing water (a water jacket),




96               PRACTICAL CHEMISTRY.
Liebig's condenser may be used for the purpose, having a widemouthed test-tube attached to the other end containing a little
lime-water; water will condense in the test-tube, and CO2 will also
be formed, which upon agitation will turn the lime-water milky.
A beaker held over a flame will show the same result, but not
quite so well.
The action of water upon metallic oxides is sometimes
very energetic. This is well seen in the slaking of lime.
Exp. 3. Get a bit of quick lime, put it on a plate and pour a
little water on it, it hisses and steam issues from it, the mass
cracking from the expansion produced by the heat of the chemical
action. A thermometer inserted into the mass will show the temperature of boiling water.
CaO + OH, = CaHo2
72. Calcic hydrate is produced.  Some of it maybe put
into a large bottle, which may be filled with cold distilled water and thoroughly shaken. A part of the lime
will dissolve, forming lime-water, the rest will fall to the
bottom  as milk or cream   of lime, which may be dissolved hereafter.  200 parts of water dissolve only one
part of lime. The solution should be kept still, and will
be perfectly clear. Should it go turbid, it must be
filtered before use.
Water transforms anhydrides into acids, as
N05 +     OH2 = 2 NOHo
SO, +     OH2 -   S,0Ho2
P20s +  3 OH- = 2 POHo,
Water also forms an important constituent of the
molecules of certain crystals, which fall to powder when
this water is driven off by heat. Such are the alums,
which crystallise with 240H2, and sulphate and nitrate
of copper, which crystallises the former with 5OH2, and
the latter with 30H,.
Some salts lose water on exposure to the air, or
effloresce, as carbonate of soda. Others, again, absorb
moisture from  the air, and become wet-deliquesce (go
to water)-as carbonate of potash, calcic, sodic, and magnesic chlorides.
Water has great solvent powers.      The solution of
solids is usually increased by heat, but a solution satu



OXYGEN COMPOUNDS.                    97
rated when hot generally gives up the solid in a crystalline form on cooling.
Exp. 4. Dissolve some acetate of lead in a test-tube, add a few
drops of HC1; a white pp. will fall of chloride of lead. Add
water, and boil, the pp. dissolves, but upon cooling, by plunging
the test-tube into cold water, the plumbic chloride will separate
again in a crystalline state.
Water on solidifying gives out the same quantity of
heat that ice absorbs on melting. A parallel case in the
crystallisation of sulphate of soda may be here introduced.
Exp. 5. Dissolve in a 4-oz. flask as much sulphate of soda
(SONao, 10 OH2) as the water will take up when boiling.  If
the solution be now corked and kept perfectly still, it will often
remain for days without crystallising. But if a crystal or the
point of a glass rod be introduced, or the liquid be even shaken,
crystals will shoot through the liquid, and the mass will become
solid-heat being given out.
On the other hand, by dissolving this salt in cold
water, heat is abstracted. On this principle the formation of freezing mixtures depends.        The following
are a few examples of such:
Pts.   COLD                   Pts. COLD
WITHOUT ICE.    by    PRO-       WITH ICE.   by   Pnomeasure DUCED.                 wt. DUCED.
Nitrate of ammonia  1  10~ to 150C Snoworcrushed ice, 2  21C
Water,...                Common salt,.       21
Sulphate of soda,.  3 1 to    Snow,          12
Dilute nitric acid,.  2  19C  Salt,..         81~C
Nitrate of ammonia 5
Phosphate soda,.  6
Nitrate ammonia..  3  10 to37~C Snow,.. 
Dilute nitric acid,.  4       Chloride calcium,. 3  to 45C
On account of its solvent powers, water is never found
perfectly pure in nature. Thus, although water evaporated from seas and rivers may be so, as it descends in
rain it dissolves gases and solids in the air, and when
it percolates through the soil, solids of various kinds are
dissolved or held in suspension. Hence the water of
G




98              PRACTICAL CHEMISTRY.
our springs contains from 5 to 20 grains of solid matter
in the gallon.   This gives rise to the term  mineral
waters.  Some of the calcareous springs near London
contain as much as 18 or 20 grains of chalk to the
gallon, or'028 of a gram to a litre. This chalk is held
in solution by the carbonic acid gas which the water
contains, and causes such water to be hard, making it
difficult to form  a lather with soap.  The hardness,
however, of such water is only temporary, as it may be
removed by boiling, by long exposure to the air, or by
the addition of carbonate of soda. Other waters which
contain sulphates are permanently hard, and this hardness cannot be removed.
73. We have waters also holding salts'of iron in solution, called chalybeate, and many others.
Besides the substances dissolved in water, there are
two other kinds of impurities.
1. Mineral substances held in suspension, which can be
removed by filtration.
2. Organic substances either dissolved or held in suspension, the former not being capable of removal.
Perfectly pure water corrodes lead, but water containing carbonic acid acts as a preservative.  Water has
several remarkable properties, which can only be slightly
touched upon here.
Its point of greatest density is about 4~C, or rather
above the freezing point. As it gets colder it expands,
so that ice occupies more space than the water did before
freezing. If this were not so, our lakes and ponds would
become solid masses of ice in winter, and all living things
in them would die.
Exp. 6. Put some water in a large test-tube surrounded by ice
in a basin, and put the bulb of a thermometer into it.  The
water will fall gradually in the tube till just above the freezing
point, when it will again expand and rise.
Water has a very high specific heat, that is, it requires
a large amount of heat to raise a certain quantity through
a certain number of degrees.
Exp. 7 (a). Mix equal weights of hot and cold water in two




OXYGEN COMPOUNDS.                  99
beakers,,marking the temp. of each. The mixture will be the
mean of the two.
(b). Again, mix equal weights of cold water and hot mercury,
marking the temp. of each as before. The water will require so
much heat to raise its temp. that the result will be less than the
mean.
(c). Thirdly, mix equal weights of cold mercury and hot water,
the temperature will be greater than the mean of the two.
The latent heat of water is also very high i.e., 79~ C.
That is, the amount of heat required to melt a certain
weight of ice, would be sufficient to raise the temperature
of the same weight of water 790 C.
Exp. 8. Put some crushed ice or snow into a beaker, and insert
the bulb of a thermometer. Heat the beaker over a sand-bath
or wire gauze, wiping off the condensed moisture from time to
time. The mercury will be found to stand at the freezing point
till all the ice is melted, the water having absorbed or rendered
latent the heat supplied. It is this latent heat that is given out
when water solidifies.
Water boils at the level of the sea at 100~ C or
200QF; but if the pressure be reduced, ebullition takes
place at a lower temperature.
74. The other compound of oxygen with hydrogen is
Hydroxyl, a body of great theoretical interest to the
chemist, as it occurs in all the oxy-acids.  Its formula
is  OH    but abbreviated the molecule is written Ho,
and the semi-molecule or atom Ho. It is hence a monad.radical, and  is capable of being   replaced  by Nao,
Ko, and its molecule by the dyad radicals Zno", Cao",
etc. It was known formerly as oxygenated water, or
peroxide of hydrogen. It can be prepared by passing a
current of carbonic acid gas through water containing
baric peroxide BaO2. Baric carbonate is produced, and
the atom of oxygen liberated combines with the water.
Ba" + C2 + OH2 = COBao" +       orH    or HO2
It may also be prepared by adding HC1 to the water
in which the baric peroxide is suspended, afterwards
adding cautiously sulphuric acid to throw    down the
barium as sulphate.




100             PRACTICAL CHEMISTRY.
BaO2 + OH2 + 2HC1 = BaC12 + OH2 + H202
Then BaCl2 + SO2Ho2 = SO2Bao" + 2HC1
Hydroxyl is a colourless liquid of syrupy consistence,
and prepared in either of the above ways appears as a
heavy liquid distinct from the water. It has an odour
something like that of chlorine. Its sp. gr. is 1'5. It
must be concentrated by evaporating over sulphuric acid
under the receiver of the air-pump. A solution of it
may be purchased at 372 Oxford Street, London, and
no doubt at other places, being used as medicine under
the name of peroxide of hydrogen
Exp. 9. Heat some of the solution of hydroxyl in a test-tube.
Oxygen is evolved, which will rekindle a glowing splinter.
Exp. 10. Blacken a lead paper with sulphuretted hydrogen and
put in the solution; it will be bleached. Clean also some discoloured white paint with the solution. It is an unstable compound, and a powerful oxidising agent.  It is used on this
account for cleaning oil paintings.
PbS + 4Ho2 = SO2Pbo" + 4H02
Metallic silver is oxidised by it, but if argentic oxide
be suspended in water, and hydroxyl added, both are decomposed.
Ag20 + H202   Ag2 + OH2 + 02
It liberates iodine from potassic iodide.
2KI + H202 = 20KH+HI,
Hydroxyl is transformed to water by the action of
nascent hydrogen (that is, just as it is generated).
Exp. 11. Generate a little hydrogen in a test-tube by the action
of dilute HC1 on zinc. Add some of the solution of hydroxyl, the
evolution of gas ceases. The same takes place when H202 is added
to the voltameter in the electric decomposition of water. Hydrogen ceases to be given off.
SO2Ho2 + Zn + H202  S02Zno+ 2012
CHAPTER XIII.
COMPOUNDS OF CHLORINE WITH OXYGEN AND HYDROXYL.
75. CHLORINE and oxygen do not combine directly with
each other, and compounds of these elements are therefore




COMPOUNDS OF CHLORINE.              101
only obtained by indirect means. They are, moreover
very unstable, many of them decomposing at low temperatures with explosion. The author would refer to Dr
Frankland's Lecture Notes for a complete list of these
compounds, as many of them are only of theoretical importance, and a mere description of them would be
beyond the scope of this elementary treatise. The oxides
or anhydrides are converted into acids by the substitution of an atom of H, or the monad radical hydroxyl,
(Ho) for an atom of chlorine.  Thus hypochlorous anhydride C1 - O - C1 or OC12 by substitution of an atom
of H becomes hypochlorous acid, C1- O - H or ClHo
(OClH). This is effected by the action of water upon
these bodies, as will be seen below.
Eaxp. 1. Pass dry chlorine gas (dried by chloride of calcium)
through a tube about six inches long containing mercuric oxide,
which must be kept cool. Connect this with a test tube surrounded by a freezing mixture (ice and salt), a yellowish gas will
pass over which will condense to a deep red liquid, emitting a
vapour of a deeper colour than chlorine.  It is hypochlorous
anhydride, mercuric oxychloride being also formed.
(HgCl
2HgO + 2C12 =   0    + OC12
HgCl
The liquid 0012 is highly explosive, decomposing by
the heat of the hand into chlorine and oxygen.
Exp. 2. Disconnect the test-tube in the last experiment, but let
it remain in the ice. Add some water to it; it will be converted
into hypochlorous acid.
001, +OH2 = 2ClHo
The same reaction takes place when chlorine is passed
into water containing mercuric oxide in suspension, or
when mercury is shaken up in a test-tube with the gas.
HgCl
2HgO + OH2 + 2C12 =      + 2ClHo
(HgCl
Hypochlorous acid is a powerful oxidising agent, giving
off chlorine when exposed to the light.
Exp. 3. Add a few drops of HC1 to the ClHo in last experiment;




102            PRACTICAL CHEMISTRY.
chlorine will be evolved from both compounds. It will bleach,
and not merely redden, a litmus paper.
OlHo + HC1 = OH2 + C12
If argentic oxide be added, oxygen is evolved from
both compounds.
OAg2 + 20HC1 = 2AgCl + OH2 + 02
Metallic oxides andhydratesare convertedinto salts called
hypochlorites, acids terminating in ous formingsalts ending
in ite. The monad radical sodoxyl replacing hydroxyl.
ONaH + ClHo = C1Nao + OH2
It was supposed at one time that chlorides and hypochlorites were both formed when chlorine gas was made
to act upon certain metallic oxides and hydrates, as in
the manufacture of bleaching powder, or the so-called
"chloride of lime," i.e.,
2CaHo, + 2C12 = CaC2I + CaC102 + 20H2
Calcic hypochlorite.
But this so-called "chloride of lime" does not contain
calcic chloride when properly made.  Calcic chloride
being deliquescent and soluble in alcohol, which is not
found to be the case with good bleaching powder.
The following appears to be the true reaction:
C2 + Ca Ho2 = Ca(OCl)Cl + OHI,
Calcic chloro-hypochlorite.
The graphic formula of bleaching powder, or calcic
chloro-hypochlorite, is C1 — Ca- O -- C1. The hypochlorites
readily give up oxygen to decaying animal and vegetable substances and also to colouring matters containing hydrogen,
and hence their use as disinfecting and bleaching agents.
Bleaching powder readily yields chlorine when acted
upon by weak acids, even the carbonic acid gas in the
air being sufficient to evolve it slowly from "chloride of
lime."
Ca(OCl)Cl + SOHo2 = S02Cao"  O  + OH + C
Ca(OCl)Cl + 2HC1  = CaClI  + OH2 + C12
Ca(OCl)C1 + CO2  = COCao" + C12




COMPOUNDS OF CHLORINE.              103
(OC1
76. Chloric Peroxide Cl-O-O-O-O-Cl      i       or C10
OC1
This is a gas at ordinary temperatures, but by slight
pressure, or by exposure to a cold of 2b~C, it can be
reduced to a red liquid, which explodes violently.  The
gas is of a deep colour, and has an irritating odour. It
decomposes slightly above the ordinary temperature of
the air, or on exposure to sunlight, and in contact with
certain bodies. It is prepared from potassic chlorate.
Exp. 4. Put a few crystals of chlorate of potash into a test-tube,
add a few drops of sulphuric acid-chloric peroxide, C1204 will
be evolved. Make a copper wire hot, and plunge it in the gas,
it explodes without danger.
Sulphuric acid should be heated very cautiously with
potassic chlorate, as the decomposition of the C1204 causes
a series of explosions, making a continuous crackling
noise, frequently projecting the materials out of the
tube. The only safe way to heat it is in a hot-water
bath.
Exp. 5. Fill an ale-glass or tall jar with water, and put it
upon a plate. Drop a small chip of phosphorus into the glass,
and cover it with crystals of potassic chlorate. Pour some sulphuric acid on to the chlorate by means of a long thistle-headed
funnel.  The potassic chlorate will be decomposed, and chloric
peroxide given off, which decomposes immediately in contact with
the phosphorus with a crackling noise, flashes of green light
appearing under water, and a greenish-coloured gas, having a sweet
odour, being evolved and dissolving in the water. The decomposition of the potassic chlorate gives potassic perchlorate, hydric
potassic sulphate, water, and chloric peroxide:
3C                O +2SIOfoKo
3 |Io + 2SO2Ho02 =      + 2SO2Ho0Io + OI2 + {
OKO                      0
zse also Exp. 5, Chap. I. (violet flame). Baric chlorate might
be substituted with the production of a green flame.
Exp. 6. Rub a crystal of potassic chlorate in a mortar with a
bit of sulphur; combustion of the sulphur takes place, with explosion. Take care to operate only on a small quantity.
Lucifer matches are tipped with a mixture of potassic
chlorate, phosphorus, and gum, and the crackling noise




104             PRACTICAL CHEMISTRY.
made when they are rubbed on the sand-paper is due to
the cause stated above.
77. Preparation of Potassic Chlorate 0{ 
This may be prepared by passing chlorine through a concentrated hot solution of potassic hydrate. Potassic chlorate and potassic chloride are both formed, but the latter
being much more soluble than the former, the chlorate
crystallises out and the other is left in solution. The
chlorate should be dissolved and re-crystallised to purify it.
3C2 + 6KHo =    o   + 5KC1 + 30H,
On account, however, of the expense of potassic hydrate,
milk of lime is used instead, whereby calcic chlorate and
chloride are produced, potassic chloride being afterwards
added to the mixture; double decomposition takes place,
calcic chloride and potassic chlorate being formed.
Exp. 7. Pass chlorine to saturation (till the liquid evolves the
gas) into milk of lime (CaHo2) kept boiling in a beaker.
OC1
0
6CaHo2 + 6CI2 = - Cao +  0aCl2 + 60112
0
OM
Filter and add a solution of potassic chloride to the mixture; potassic chlorate and calcic chloride will be formed. The calcic chloride being very soluble in water, the potassic chlorate will separate
on cooling. The " mother liquid " being drained off, the chlorate
should be re-crystallised, as above
OC1
Cao" + 2KC1 = CaCI2 + 2 OC1
00
OC1
The acid, of which potassic chlorate is a salt, is
Chloric acid, its formula being   H —O —O —-C1
} OHo or 0
I001 on~OC1
The acid itself, however, is unimportant.   It may be
prepared from baric chlorate by the action of sulphuric
acid. The chlorates are all soluble, and cannot therefore




BORON.                    105
be precipitated from their solutions. They give up their
oxygen more readily than the nitrates, which are somewhat similar in their properties.
If potassic chlorate be heated till one-third of its oxygen is given up, and the fused mass be allowed to cool,
when dissolved in water a salt will crystallise out from
the chloride, which contains one atom of oxygen more
than the chlorate. It is potassic perchlorate, and has
the formula KC10O
2 0 KC+     0   +02
OKo-   1    ~ OKo
This occurred as a secondary product in making chloric
peroxide, and was mentioned also under the head of
(oc1 
oxygen.  From this, perchloric acid  OHo  is prepared
( OHo )
by the action of sulphuric acid.  It is a powerful oxidising agent.
CHAPTER XIV.
BORON B".
78. TiHn is a triad element. It is never found in a free
state in nature. Its principal sources are-tincal, a crude
kind of borax obtained from certain lakes in Thibet; and
boracic, or boric acid, obtained from the lagoons in the
volcanic district of Tuscany. It has also been found
lately, in combination with soda, in the lakes of California and Utah-this being also crude borax or sodic
*borate (B4,ONao2). From borax, the tribasic boric acid
(BHo3) is prepared by the action of hydrochloric or sulphuric acids.
Exp. 1. Prepare a hot saturated solution of borax in a beaker.
Add strong -,C1 till the solution reddens blue litmus paper. Crystals of boric, or boracic acid separate on cooling, sodic chloride
being left in solution.
B,40Nao + 2HC1 + 50H2 = 4BHo3 + 2NaCl.
The crystals should be washed with water and spread




106              PRACTICAL CHEMISTRY.
on a filter paper.- They consist of flat plates having a
pearly lustre and greasy to the touch. They are soluble
in hot water and alcohol. Their solution in water imparts a port-wine tint to litmus.   BHo5 is a weak acid
in the cold, and turns turmeric paper reddish brown, even
when free HC1 is present.
Exp. 2. Dissolve some of the crystals in methylated spirit. Inflame the spirit-the BHo8 volatilises and imparts an apple-green
colour to the flame. Borax may be dissolved, but requires the
addition of HC1 or S02Ho, to liberate the acid.
Boric acid will expel OO2 from the solution of a carbonate on
boiling.
Exp. 3. Make a saturated solution of carbonate of soda in a testtube, and add some crystals of BHo,, obtained in last experiment.
Fit a cork and tube, and a bit of flexible tube, to lead into another
test-tube containing lime-water. Heat to boiling; carbonic acid
gas will be evolved, and turn the lime-water milky.
3CONao2 + 2BHo, = 2BNao, + 3CO2 + 30H2
By heating crystals of the tribasic boric acid to the boiling point,
they lose water, aifd are converted into an acid having the composition BOHo, called metaboric.acid.
BHo3 = BOHo + OH2
Exp. 4. Heat some of the crystals to redness on charcoal before
the blow-pipe flame, they become anhydrous, and partly volatilise
if the heat be continued. They are converted into boric anhydride
O =B-   - B =O or B20,. If this boric anhydride be heated with
sodium on charcoal before the blow-pipe, sodic oxide will be formed,
and gritty, amorphous, brownish-black pieces of Boron will appear
mixed in the mass.
B203 + 3Na2 = 30Na, + B2
The element exists in two allotropic states:a. Amorphous. b. Graphitoidal or diamond boron.
It combines directly with nitrogen, which few elements
do, forming boric nitride B"' N'. Also with chlorine, &c.
Exp. 5. Fuse in a porcelain crucible a mixture of two parts by
weight of sal-ammoniac (ammonic chloride NH4C1) and one ounce
powdered borax. Abundance of white fumes will be given off from
HC1. A white mass will be left, consisting 6f NaCl and BN.
Dissolve out the sodic chloride, and a white amorphous infusible
powder will be left. For this, and other reactions, see Dr Frankland's Lecture Notes.
The most important compound of boron is borax. It
is a borate of soda.    Upon ignition, the crystals lose




CARBON.                    107
water and become anhydrous (refined borax). It is
largely used for glazing pottery, forming a glass-like compound with metallic oxides. It is also used for soldering,
on account of its property of dissolving the film of oxide,
thus keeping the surfaces of the metals clean and enabling
them to alloy with one another. The same property
makes it of great use in Analytical Chemistry, the borax
dissolving certain metallic oxides, which impart a particular colour to the glassy mass.
Exp. 6. Take a bit of platinum wire about 5 inches long, and
turn it up at the end, forming a loop. Heat it to redness in
the Bunsen flame, and then dip the loop into powdered borax.
Heat the mass taken up before the blow-pipe, it swells up and
fuses to a transparent bead. Whilst hot, dip the bead into
a solution of nitrate of cobalt, and heat again strongly, the
bead will be coloured blue. Salts of copper, iron, manganese,
nickel, and chroninm, impart their own characteristic colours
to borax beads.  The chlorides are best for the purpose, or
nitrates.
CHAPTER XV.
CARBON CIV.AND ITS COMPOUNDS WITH OXYGEN.
79. CARBON is one of the tetrad elements.   One of its
compounds with hydrogen has been already alluded to, but
such compounds, which are very numerous, form a separate branch of the subject under the head of Organic
Chemistry, sometimes called the chemistry of the carbon
compounds.
Carbon exists in three allotropic states: crystallised, and
almost pure in the diamond, with a sp. gr. of 3'3; in
flat tabular plates, as in graphite or black-lead, sp. gr. 2.15;
the black scales found in pig-iron consist of this variety
of carbon; and, amorphous, as in the different kinds of
chiarcoal. Coal, coke, and lamp-black also contain hydrogen, oxygen, and earthy matters.
Wood charcoal is made by burning billets of wood
made into heaps, covered with clay to prevent access of




108              PRACTICAL CHEMISTRY.
air except in a few places.  The inflammable gases burn
away, and charcoal is left.    Or, it is heated in iron
cylinders, the gases and vapours evolved being made to
pass through a pipe into receivers, where they are condensed.
Exp. 1. Light a splinter of wood, and plunge it into a testtube. It will only burn with a flame at the mouth of the tube.
The part inside will glow, and at last become a charred mass.
The wood consists principally of C, H, and 0; the two latter
burn away and leave the carbon. Brown tarry matters condense
on the sides of the tube. If small pieces of wood are heated in a
test-tube, to which a glass delivery-tube is adapted, the gases and
vapours may be condensed-among which may be recognised tar
and pyroligneous acid, which will redden litmus.
Wood may be heated in a Cornish crucible, loosely covered
with a bit of earthenware, with the same result. Carbon is infusible.
Animal and vegetable charcoal are very porous, and
have the power of absorbing gases.
Exp. 2. Collect a jar of dry hydrochloric acid gas over mercury,
and plunge a piece of heated charcoal under the jar. The gas
will be absorbed, and the mercury rise in the jar. See also Exps.
4 and 5, page 81. Mercury only being used.
Charcoal absorbs 90 times its volume of ammonia gas, 85
HC1, 55 of sulphuretted hydrogen, nearly 10 of oxygen, and 2 of
hydrogen.
It is on this account used as a disinfectant; the best
explanation of the process being, that oxygen is condensed
in the pores of the charcoal, and the putrescent substances become oxidised..Exp. 3. Shake up a piece of tainted meat in a test-tube containing water and some finely powdered charcoal, the smell will disappear. Stagnant water may be deodorised in the same way.
80. Animal charcoal has the power of absorbing colouring matters, and many bitter principles when in a finely
divided state, in addition to its power of absorbing gases.
On this account it is used for filters, and in the decolourisation of sugar in sugar refining.
Exp. 4. Get some dark brown sugar (foots) and make a strong
solution of it. Put some animal charcoal or bone-black into a
large boiling-tube, and pour the solution of sugar into it. Shake
it well and pour it upon a filter, a pale, straw-coloured liquid will




CARBON.                     109
run through. If the process be repeated, the whole of the colour
will be retained by the charcoal, but the syrup loses none of its
sweetness.
Port wine acted on in the same manner loses its colour and also
its aroma.
81. Oxygen Compounds of Carbon. When any kind
of carbon is burnt in oxygen, carbonic anhydride, usually
termed carbonic acid gas, is produced. Thus, when a
small splinter of diamond is suspended on a bit of platinum foil in a jar of oxygen, and an electric current,
sufficiently powerful to heat the foil-and hence the diamond-to redness, it glows and swells up like a mass of
coke, carbonic anhydride C02 is produced, and a very
small quantity of ash, or earthy matter, is left.
A piece of graphite from a lead pencil heated to redness in a Bunsen flame, and plunged into oxygen, also
produces CO2.
Lime-water poured into the jars in either case is turned
milky from the production of chalk or calcic carbonate.
CaHo3 + C02 = COCao" + OH,
Exp. 5, Chap. XI., may be repeated here.          No
change of volume takes place when carbon is burnt in
oxygen. Carbonic anhydride is prepared by the action
of HC1, SO2Ho2, or vinegar upon a carbonate.    HC1 is
the best to use, as the chloride of calcium formed is more
soluble than the sulphate, which is apt to form a coating
over the substance, and prevent the further action of the
acid.
Exp. 1. Put into four beakers some old mortar, powdered oyster
shells, limestone or chalk, and pounded coral. Pour upon each
of them some HC1 or dilute sulphuric acid. An invisible gas will
come off, which will extinguish a lighted taper lowered into it.
The carbonic anhydride evolved is a non-supporter of combustion.
Exp. 2. Break a piece of white marble —calcic carbonate in a
crystalline state-into small pieces, and put it into the hydrogengenerating bottle.  Cover it with water, and pour on it some
HC1. A violent effervescence will take place, and CO2 will be
evolved. It may be collected over water in the pneumatic trough
as usual, although water dissolves its own volume of the gas.




110              PRACTICAL CHEMISTRY.
The water is put into the generating bottle to dissolve the calcic
chloride formed. Shells, chalk, and coral consist principally of
calcic carbonate, and the action of acids upon them is the same as
upon marble-but marble is preferable, as it does not froth up so
much.
COCao" + 2HC1 = CaCl2 + OH2 + CO2
Collect several jars or bottles of the gas in this way.
It may also be collected by downwards displacement, as
in the case of chlorine.
Exp. 3. Plunge a lighted taper into a jar of the gas, it will be
extinguished.
Exp. 4. Fill a bottle with water, and then half fill it with CO.
Cover it with the hand and shake it well. The hand will be
pressed in, showing that the gas has been dissolved. Open it in
trough, water rushes in. Pour in some lime-water, it turns milky,
but upon agitation it re-dissolves. Chalk or calcic carbonate,
though insoluble in water, is soluble in water containing carbonic
acid gas. This enables our sea and river waters to hold chalk in
solution.
Exp. 5. Boil some of the water containing the dissolved chalk,
it will be re-precipitated.
Exlp. 6. Pour a solution of litmus into a jar of carbonic anhydride, it is turned wine-red. Carbonic acid has never been isolated,
but the dry gas would not affect a dry litmus paper.
82. Carbonic anhydride is a very heavy gas, its density
compared with hydrogen being 22. A litre of the gas
would weigh -0896 x 22 or 1-9712 grams.       Its weight
compared with air is therefore    2y or 1 529.
Exp. 7. Fill a large bell-jar with CO, by downwards displacement, the heavy gas lifting out the air. Cover with a glass plate
all but the opening left for the delivery-tube. The gas may be
tested from time to time by a lighted taper. When full, the taper
will be extinguished at the opening, as the jar will run over.
Tie a string round a small beaker to act as a pail, and bale ou0t
a beaker of the gas, which pour on to a lighted taper.
Exp. 8. Make some lather, and blow soap-bubbles, letting them
fall into the large bell-jar of CO2. They will float on account of
the greater lightness of the contained air.
The atmosphere contains about 4 parts in 10,000 or
~04 per cent. of carbonic acid gas. This is largely increased where great nulbers of persons are congregated




CARBON.                    111
together, unless there be a good current of air. Even 2.
per cent in the air produces discomfort, 5 per cent. or less
faintness, and 10 per cent. would be absolutely fatal. Air
that is exhaled from the lungs contains 5 per cent. more
CO2 than that which is inhaled.  This is produced from
the chemical union of waste matters with the oxygen of
the air. This is constantly being thrown off from. the
blood.
Exp. 9. Leave a saucer containing lime-water exposed to the
air, a crust of carbonate of lime or chalk will be formed upon it.
Exp. 10. Breathe through a glass tube into lime-water. It
turns milky from the CO2 contained in the breath.
A few drops of HC1 dissolves the calcic carbonate formed.
Air drawn through lime-water into the lungs does not
affect it, owing to the smallness of the quantity of CO2.
If the air drawn in be sent into another vessel also containing lime-water, as in Exp. 10, it turns milky.  An
ingenious bit of apparatus for showing this experiment
is shown in Fig. 37. It consists of two small flasks, each
provided   with   corks
fitted  with two tubes.
One tube in a passes
into the lime-water, the
other just passes through 
the cork, and is connected
with a flexible tube leading to the mouth, provided with a valve of
oiled silk  opening in- — _
wards. The mouth-piece         _
is also connected with the     -
tube, having avalve open-          Fig. 37
ing outwards, which enters the lime-water in b, and when
air is driven out of the lungs it turns it milky. Several
full inspirations and expirations being taken, the effect is
very marked.
Exp. 11. Burn a taper in a bottle till it goes out. Then pour
in lime-water, it will turn milky. CO2 is produced in the burning of our lamps, gas, candles, and fires.




112            PRACTICAL CHEMISTRY.
It is also produced in all cases of fermentation.
Effervescent drinks are produced by the action of some
acid on a carbonate. And in consequence of the solubility
of the gas, aerated waters are made by forcing the gas
into them by great pressure. The gas, on account of its
weight, collects in brewers' vats. It is also found in old
wells and caverns. A lighted candle should be lowered
into such places before a man is allowed to descend, as
fatal accidents may occur if this precaution be neglected.
Limestone or chalk, when heated to redness in a kiln,
give off CO2, and become calcic oxide or quick-lime.
Magnesium wire ignited and plunged into a jar of CO2
decomposes it, and carbon is deposited. If dry CO2 be
sent through a bulb-tube containing potassium heated to
redness it is likewise decomposed.
If, however, carbonic anhydride be passed through an
iron tube containing charcoal, heated to redness in a
furnace, it will be decomposed and take up another atom
of carbon, forming a gas with one half the oxygen called
carbonic oxide CO. Or,
_Exp. 12. Pass a stream of CO over powdered charcoal contained
in a hard glass tube about ten inches long, heated to redness by
Herepath's blow-pipe. The carbonic oxide will burn at the end of.
the tube with a beautiful blue flame.
CO2 + C= 2CO
This gas is often seen burning at the top of a clear
fire. Carbonic acid is produced by the burning coals at
the bottom of the grate, and in passing through the red
hot fire is decomposed, and takes up another atom of
carbon. The CO burns at the top of a clear fire with a
blue flame, forming CO2. If our fires could be fed from
the bottom, and brilliant combustion produced, so that
the carbon could be heated to redness, very little smoke
or unburnt carbon would be produced.   It is on this
principle furnaces are constructed to consume their own
smoke, great saving of the fuel being effected. Be careful not to inhale carbonic oxide, as it acts as a direct
poison.




NITROGEN.                    113
Exp. 13. Heat some bits of chalk with charcoal in a test-tube
of hard glass by means of the Herepath. The carbonate is decomposed and CO produced.
83. Carbonic oxide is usually prepared by decomposing
oxalic acid by means of sulphuric acid, which abstracts
the elements of water from this compound, CO2 and CO
are both formed.
Exp. 14. Put some oxalic acid into a flask, and pour on it
some SOHo,. Heat gently, and convey the mixed gases through
lime-water or solution of caustic soda in a Woulff's bottle. The
CO, will form calcic or sodic carbonate, and the carbonic oxide
may be collected over water as usual. Collect two jars of the gas.
Exp. 15. Inflame a jar of CO, and immerse a lighted taper in
the gas, it will be extinguished.
Exp. 16. Pour some lime-water into a jar of CO and agitate it,
no milkiness is produced. Inflame the gas and then shake it
again, the lime-water will turn milky. The CO combines with
the oxygen of the air and forms CO2 again. This takes place at
the top of the clear fire as mentioned above. When burnt it forms
an equal volume of CO2.
Carbonic oxide may be prepared by adding sulphuric
acid to ferro-cyanide of potassium (yellow prussiate of
potash). Care must be taken, however, as ferro-cyanic
or prussic acid may be produced at the same time.
12 +16   28
The sp. gr. of CO compared with H is 12    16     2  or
2      2
14; and with air'9724. A litre of the gas weighs
1 254 grams.
Question 1. How much CO2 can be obtained from 100 grams
of calcic carbonate by the action of HC1?
Ans. 44 grams or 22'320 litres.
2. What is the weight of 10 litres of carbonic acid gas compared
with hydrogen as unity?
Ans. 19'7120 grammes.
CHAPTER XVI.
NITROGEN-THE   ATMOSPHERE-COMBUSTION FLAME-THE
BLOW-PIPE.
84. NITROGEN NV is a pentad element. It forms A of
the atmosphere, which is a mechanical mixture of this
II




114              PRACTICAL CHEMISTRY.
gas with oxygen and a little carbonic acid and watery
vapour in varying proportions. It may be obtained
from the air in various ways by withdrawing the
oxygen.
Exp. 1. Graduate a stoppered bell jar, dividing it into five equal
portions by pasting a slip of paper down the side. Put a bit of
phosphorus in a small evaporating
dish and float it upon water. Ignite
the phosphorus and cover it with the
jar. The phosphorus will burn at
the expense of the oxygen of the air
contained in the jar, forming P201
When the contents of the jar cool
the water will rise and occupy onefifth of the space. The remaining
i4 lj1I.;  l    four-fifthsof the jar containnitrogen.
On plunging a lighted taper into
FA^. 38.the gas it will be extinguished. Nilig. 38.         trogen is a non-supporter of combustion.  It has no action upon test-papers, it is therefore a
neutral body. It does not turn lime-water milky.
Exp. 2. Repeat the last experiment, aid then restore the fifth
part with which the phosphorus combined by sending oxygen into
the jar. A candle will burn in the mixture as it does in air, so
that air is not a chemical compound.
Exp. 3. Shake up a measured quantity of air in a test-tube with
a solution of pyrogallic acid in strong caustic potash.  This
absorbs the oxygen. That which remains will be nitrogen.
The volumetric composition of air may be proved by
exploding a measured volume with hydrogen in the
eudiometer mentioned in Exp. 1, Chap. XII., but such
experiments are difficult for students.  Nitrogen may
also be obtained by passing air over red-hot copper; the
metal unites with the oxygen, leaving the nitrogen.
Nitrogen may be obtained frtm      several of its compounds.
Exp. 4. Heat in a 2-oz. flask some of the salt called ammonic
nitrite (formed by the action of nitrous acid upon ammoniashown here as the oxide of the body ammonium NH4). It splits
up into nitrogen, which is evolved, and water. The gas can be
collected over water as usual.
NO (NH40) = 20H2 + N2
* Keep the hand on the jar till the P. goes out.




NITROGEN.                  115
Exp. 5. Heat in a small flask a mixture of ammonic chloride
and sodic or potassic nitrite. Nitrogen is given off.
NHC01 + NONao = NaCl + 20H2 + N,
85. Nitrogen can also be obtained by passing chlorine
gas through an excess of strong solution of ammonia contained in a three-necked Woulffs bottle. The ammonia
must be in excess, or a terribly explosive compound called
chloride of nitrogen NC13 will be formed in brown drops
by the combination of some of the chlorine with the
nitrogen of the ammonia. The safety-tube, which must
be a funnel in this case, must be constantly smelt to
ascertain whether free ammonia be present. The reactions are given below.
It is not advisablefor a student to try the experiment.
8NH4Ho + 3C12 = 6NH4C1 + N2 + 80H2
Dangerous. NH4Ho + 3C12 = NC13 + OH2 + 3HC1
86. Nitrogen does not combine readily with other elements at ordinary temperatures. When a flash of lightning passes through air, it causes some of the oxygen and
nitrogen to combine, and with moisture to form nitric
acid. When electric sparks are passed through air, the
same result is produced, as may be shown by the action
on blue litmus paper, which will be reddened.
The composition of the air is very constant, varying
but little, whether taken from the mountain top, or at
the sea level. The air of towns contains various impurities, and all air contains watery vapour, together
with a small quantity of carbonic acid gas which is being
constantly exhaled by animals, and absorbed by the
leaves of plants.
Percentage composition of the atmosphere.
By volume.     By weight.
Nitrogen,..   79'1           76'9
Oxygen,...   20'9           23-1
1eo0           100o
We cannot do better than introduce at this stage a few
remarks on the phenomena of combustion.




116             PRACTICAL CHEMISTRY.
87. Combustion takes place when chemical action is sufficiently violent to heat bodies to redness. We usually
call the body so heated a combustible, and the gas or
vapour in which it burns, the supporter of combustion.
Hence wheA hydrogen is burnt in air or oxygen, it is
usual to say hydrogen is the combustible body and oxygen the supporter of combustion. In the same manner
we say sulphur is combustible when burnt in oxygen.
But, if sulphur be heated in a flask till it gives off vapour,
copper leaf will burn in it, the sulphur being in this case
the supporter of combustion. A jet of hydrogen will
burn in chlorine, the latter being the supporter of combustion, according to the ordinary phraseology, but it
would not be difficult to show that chlorine will burn in
hydrogen, when chlorine would appear to be the combustible body and hydrogen the supporter of combustion. Combustion, however, is in fact nothing more than
chemical combination at a great heat.
Exp. 6. Get an ordinary gas chimney;
fit a large cork to the end, perforated with!'~flj ~two holes for glass tubes, as in Fig. 39,
which is a similar arrangement, only
having a metal base. Fix it by a clip to
a stand, and put a bit of fine wire gauze
at the top of the cylinder.  Close the
tube a with a cork, let gas in to the
bottom of the cylinder by the tube b,
and light it at the top of the wire gauze.
|a            Coal gas will of course fill the cylinder.
Now pass a lighted match through a,
and a shell of flame appears at the top
/bf  |    of the tube, the air appears to burn ill
=       — = —  - the coal gas. The breath from the mouth
may be substituted for the air by attaci -
ing a piece of flexible tube to a. The air
Fig. 39.      and gas burn really only where they
come in contact with one another.
For bodies to burn, they must first be raised to a certain temperature. This is called the igniting point. In
some cases a moderate heat is sufficient to set up combustion; the friction on the sand-paper being sufficient
to inflame the phosphorus on the lucifer match, Some




COMBUSTION.                    117
bodies require intense heat to make them burn, whilst
zinc ethyl burs at the ordinary temperature of the air,
and carbonic disulphide when a hot glass rod is brought
near it. In the latter case, as in many others, the substance gives off vapour, and it is this which inflames.
Exp. 7. Pour a little ether into an evaporating dish and bring
a light near it. The ether gives off vapour at the ordinary temperature of the air, and this inflames.
Alcohol and paraffin must be warmed gently before sufficient
vapour is produced to inflame. Some kinds of the latter, however, give off vapour at a very low temperature, and are hence
dangerous.
The ordinary candle flame is produced by the burning
wick converting the wax or tallow into vapour, and it is
this which inflames.
88. Flame is produced by burning gas or vapour, and
the more intense the agitation the brighter is the flame.
Hence the flame of coal gas, which consists of a mixture
of gases and vapours, is greatly intensified by a jet of
oxygen being introduced into it, the combustion being
more vivid.
The conical form of a flame is caused by ascending currents of air. The flame of a candle consists of three concentric'cones. The outer one, which is scarcely perceptible,
is the area of complete combustion, where the oxygen of the
air comes in contact with the burning gases and vapours;
it is sometimes called the oxidising flame.  The next or
middle shell is the area of partial combustion sometimes
called the deoxidising flame.   The centre of the flame is
hollow, consisting of the unburned gases.
Exp. 8. Put a piece of wood across a candle flame, it will be
charred on each side of a central part, which is not discoloured;
or, lower a card upon the flame, a black ring will be produced.
Exp. 9. Put some gunpowder on the wire gauze at the top of
the cylinder in Exp. 6. Then light the gas. The gunpowder will
not inflame till the gas is lowered considerably, showing that the
flame is hollow; or allow gas to pass through a bit of wire gauze,
while a light is applied above, the flame does not pass through.
The gauze cools the flame. This is the principle of Davy's safety
lamp.




118              PRACTICAL CHEMISTRY.
The Bunsen flame is not hollow, the air mixing with
gas as it passes up the tube.
The blow-pipe flame consists of two parts only, as air
is blown into the middle, of the flame. The outer is
called the oxidising, and the inner the deoxidising flame,
as above.
Familiarity with the use of the blow-pipe may be obtained by trying the following experiments:E'xp. 10. Put some red lead in a little hollow, scooped in a bit of
charcoal. Heat strongly just at the point of the inner cone. The
Pb304 will be reduced, and a bead of metallic lead will appear.
Heat this bead in the outer flame and a yellowish-red incrustation
will appear on the charcoal, the metal being oxidised again.
Exp. 11. Heat some sulphate of zinc on charcoal, and a yellow
incrustation will appear, which becomes white when cold. It
consists of ZnO.
Exp. 12. Mix some cupric chloride with carbonate of soda, and
heat strongly in the inner flame; red scales, consisting of the metal
copper, will be obtained. The CONao2 acts as a flux, and renders
the copper salt more easily fusible.
Exp. 13. Mix some oxide of tin with potassic cyanide, or a
mixture of carbonate of soda and potassic cyanide (fusion mixture),
and heat on charcoal in the inner blow-pipe flame. The SnO will
be reduced, globules of metallic tin will be produced with a slight
incrustation if brought into oxidising flame.
CHAPTER XVII.
OXIDES AND OXY-ACIDS OF NITROGEN.
89. NITROGEN forms five distinct compounds with oxygen,
and two of these are converted into acids by the addition
of water; or, the latter may be considered as compounds
of certain oxides with hydroxyl.
The most important compound of nitrogen is nitric
acid.  This is prepared from    either of two of its compounds called potassic nitrate (nitre or saltpetre), and
sodic nitrate, called also cubic nitre or Chili saltpetre.




NITRIC ACID.                  119
Potassic nitrate, NO2Ko-one of the ingredients in
gunpowder-is found as an efflorescence on the soil in
India, and nitrate of soda NO2Nao, which cannot be
used for manufacture of gunpowder as it is deliquescent,
in a similar state in Chili and Peru. Either of these
salts, heated with sulphuric acid, are decomposed, sulphates of the metals being formed, and nitric acid distils over.
Esp. 1. Heat some potassic nitrate in a small stoppered retort
(Clark's retort, mentioned in Chap. IV., will do well for the purpose) with some strong sulphuric acid, keeping
the receiver cool, as in Fig. 40.  Orangecoloured vapours will be produced at the beginning, and again towards the close of the
experiment, arising from the decomposition of
some of the nitric acid produced. A pungent-  Fig. 40.
smelling, fuming liquid will distil over, with
a yellow tinge from the solution of some of the above-mentioned
vapours.
A blle litmus paper will be instantly reddened.
One of the two atoms of hydroxyl in SO2Ho9 is
exchanged for potassoxyl, hydric potassic sulphate being
left as a white mass in the retort, whilst nitric acid NO2Ho
will distil over.
NOKo + SO2Ho2 = SOHoKo2 + NOHo
In the manufacture of nitric acid upon a large scale,
the materials are put into iron cylinders lined with fireclay which are heated in a furnace. On account of the
great heat which can be obtained by this method, onehalf the sulphuric acid need only be used, the neutral
sulphate SO2Ko2 being produced.    The heat, however,
destroys some of the nitric acid. The acid is colourless
when pure, but the commercial acid is yellow and contains iron and traces of sulphuric acid.
Exp. 2. Heat some colourless nitric acid in a test-tube, orangered fumes will be produced by the decomposition of the acidoxygen being liberated, and peroxide of nitrogen formed.
4N02Ho = 20H2 + 02= 2N204
90. Nitric acid is monobasic, and therefore forms but
one class of salts, there being no acid Nitrates.




120              PRACTICAL CHEMISTRY.
Nitrates are formed by the action of nitric acid upon
metallic oxides and hydrates, and upon certain metals.
They are all soluble, and are all decomposed by heat,
the oxides of the metals being mostly formed.
Nitric acid is used as a solvent for many metals. It
is a powerful oxidising agent.  Thus, tin acted on by
concentrated nitric acid withdraws 1 of the oxygen, with
the production of nitric peroxide N504; silver, in cold
dilute acid, abstracts -- of the oxygen, with evolution
of a red vapour of nitrous anhydride N203; copper or
mercury withdraws A- of the oxygen, with the production of nitric oxide N202; and zinc, under proper conditions, removes 4 of the oxygen, with the production
of nitrous oxide N20. The body nitric anhydride N205,
which added to water is transformed into nitric acid, is
usually obtained by passing dry chlorine over argentic
nitrate.
Exp. 3. Pour some of the nitric acid obtained in Exp. 1 upon
some Dutch metal in a test-tube; violent chemical action will take
place, the metal dissolving.
Exp. 4. Pour some strong nitric acid upon gold leaf in a testtube; no effect is produced.
Exp. 5. Pour some strong HC1 on gold leaf; no effect.
Exp.,6. Add the two together; the gold dissolves,-the mixture
of nitric and hydrochloric acids is called aqua-regia. The nitric
acid oxidises the H of HC1, forming water; whilst the nascent Cl
combines with the gold, forming auric chloride Au C13. The liberation of the chlorine is shown by the following equation2N2HoT + 6HC1 = N204 + 20H2 + 3C12
Exp. 7. Put some'nitre in an old flask, heat it strongly; it will
melt. While in a fused state pour in some powdered charcoal,
and take the lamp away. A brilliant deflagration will take place,
which will most likely break the flask. It is well, therefore,
to put a basin of water under it. Nitre and charcoal form two of
the ingredients in gunpowder, the former oxidises the latter,
forming CO2.
91. Nitrous Oxide NO, or laughing-gas, is prepared
by heating ammonic nitrate in a small retort. The salt
splits up into water and nitrous oxide.  The gas should
be collected over hot water. Ammonic nitrate is formed
by adding nitric   acid to a solution    of commercial




OXIDES OF NITROGEN.                121
ammonic carbonate till the solution is neutral to testpapers, evaporating the solution to dryness. The gas
should not be inhaled, except under medical advice.
NO2(NH40)=20H2 + ON2
Exp. 8. Heat some ammonic nitrate in the small Clark's retort,
Fig. 40, and collect two jars of the gas. The whole of the salt will
volatilise.
Exp. 9. Insert a glowing splinter in the gas, it will be rekindled. A lighted taper will burn very brilliantly in the gas as
in oxygen. The gas is decomposed.
Exp. 10. Just ignite a bit of sulphur and plunge it in the gas,
it will be extinguished. Thoroughly inflame the sulphur and it
will burn in the gas with a peculiar flame, the gas being decomposed.
92. Nitric Oxide  NO       N
NO io NO          N    0
This is a colourless gas. It is prepared by the action
of nitric acid upon copper, with the production of cupric
nitrate, water, and NO22 as a gas.
3Cu + 8NO2Ho = 3 N        o2 Cud' + 40H2 + N20
Exp. 11. Put into a wide-mouthed flask or Woulff's bottle, furnished with a thistle-funnel and delivery-tube, some copper clippings. Cover them with water, and pour strong nitric acid down
the funnel. Red fumes will soon fill the flask, caused by the
mixture of the gas evolved with the contained air. These soon
disappear, and a colourless gas comes over, which is to be collected
over water in jars. It is nitric oxide.
Exp. 12. Moisten a roll of blue litmus paper with sodic hydrate,
and plunge it into a jar of the gas. Red fumes rapidly form down
the jar, reddening the litmus paper above but not below, till the
red fumes fill the jar.
The nitric oxide rapidly combines with the oxygen of
the air to form  nitric peroxide N204 and nitrous anhydride N203. The latter is converted into nitrous acid
by the action of moisture.
N22 +   2   =  N204
or N22 + 02   = 2N20
and N20a + OH2 = 2NOHo
Nitric oxide is a test for oxygen, ruddy fumes being




122             PRACTICAL CHEMISTRY.
produced as above when the two gases come together.
This distinguishes oxygen from nitrous oxide, which
rekindles a glowing splinter, but does not produce red
fumes. Nitric oxide is completely dissolved by a solution
of ferrous sulphate, forming a reddish liquid.
Exp. 13. Pass bubbles of oxygen into a jar of the gas standing
over water in the pneumatic trough. The deep red gas produced
will be speedily dissolved by the water which rises in the jar.
Exp. 14. Pass nitric oxide into a jar of oxygen, as in Exp. 11,
Chap. XI., or into a jar of air.
Exp. 15. Plunge a burning taper into nitric oxide, it burns
with a peculiar bright flame. A glowing splinter will not, however, be rekindled, the heat not being sufficient to decompose the
gas.
Eaxp. 16. Just touch a bit of phosphorus with a hot wtre in a
deflagrating spoon, and plunge it quickly into the gas, it will be
extinguished. If, however, the phasphorus be well alight before
it is immersed in the gas, the heat will be sufficient to decompose
it, and then the oxygen liberated will make it burn brilliantly.
93. Nitrous anhydride N203 is obtained by boiling nitric
acid with starch or arsenious anhydride (white arsenic
As20), a deep-red gas comes off, which condenses to a
blue liquid in a bulb kept in a freezing mixture. It is
also produced when silver is acted on by cold dilute
nitric acid.
As20, + 2N02Ho = As205'+ H02 + N20,
6NOHo + 2Ag2 = 4N02Ago + 30H2 + N20
Liquid NO2 with a small quantity of water produces
nitrous acid NoHo, but with a large quantity, N202 is
evolved.
OH2 + N20   = 2NOHo
OH2 + 3N203 = 2NOHo + 2N202
94. Nitrous acid NOHo produces salts called nitrites.
These are frequently found in the well waters of towns,
from  the oxidation of ammonia.     Sodic nitrite was
mentioned as a source of nitrogen in Chap. XVI.   It is
obtained by fusing sodic nitrate in a porcelain crucible.
The fused mass decomposes. On cooling and dissolving
a portion, it should give an alkaline reaction to testpaper.  Nitrous acid sometimes acts as a reducing agent,




AMMONIA.                   123
abstracting oxygen from unstable compounds containing
it. At others acting as an oxidising agent.
Exp. 17. Add a solution of permanganate of potash to a solution
of sodic nitrite, made slightly acid by a few drops of HCO; the
colour will be discharged from loss of oxygen.
Sodic nitrite added in the same manner to water, tinted with
magenta, acts as an oxidising agent.
Or 7204 has been already
95. Nitric peroxide  N2 or N04 has been already
prepared by passing nitric oxide into air and oxygen.
Exp. 18. Shake up a test-tube of the gas with a solution of
hydroxyl; the red fumes disappear and an intensely acid liquidnitric acid-is produced.
N2 + Ho2 = 2NO2Ho
CHAPTEP     XVIII.
AMMONIA AND AMMONIC SALTS.
96. AMMONIA is a gas having the composition NH,.
There is, however, no known means of making the elements composing it unite directly with each other. It was
formerly obtained by the destructive distillation of animal
substances which are rich in hydrogen and nitrogen. It
is now obtained from the refuse gas liquors which float
on the tar, in which it exists as ammonic carbonate.
Hydrochloric acid is added to this, ammonic chloride is
formed, and carbonic acid escapes. The ammonic chloride
being obtained from the solution by evaporation is purified
by sublimation. From this ammonic chloride ammonia
gas is obtained by heating with slaked lime. The gas
is very soluble in water, and must therefore be collected
over mercury or by displacement.
2NHC1 + CaHo2 = CaCl2 + 2NH3 + 20H,
x.p. 1. Rub some ammonic chloride (sal ammoniac) to a
powder in a mortar. Then mix with it about the same weight of




124              PRACTICAL CHEMISTRY.
slaked lime. Put it into a flask with a long delivery-tube bent
upwards as in Fig. 41. Add water to make it into a thick paste, and
let the delivery-tube from the flask pass to the top of a bottle
supported in an inverted position on the ring stand. Heat gently.
The gas, which is lighter than air, will rise to the top of the bottle
and push the air downwards. Hold a turmeric paper to the mouth
of the bottle from time
to time, itwill be turned
brown when the bottle
is full. Immerse a taper
in the gas, it will be extinguished.
Collect another jar of
the gas, and a narrow.^.A-  -v  tube of stout glass, as
used in Exp. 4, Chap. X.
~~l~,_~ _WExp. 2. Bring the
end of the stout glass
tube below the surface
of the water. Remove
the finger, and shake
Fig. 41.              up the small quantity
of water which enters
first. Introduce it again into the trough, the water will rush up
with great violence. Water dissolves 780 times its volume of
the gas.
Exp. 3. Prepare a jar of HC1 (see Exp. 2, Chap. X.), and bring
a jar of ammonia over it. Remove the glass plates. The two
gases will combine together and form a solid white body, ammonic
chloride NH4C1.
A glass rod moistened with HC1 held over the bottle of ammonia
will produce white fumes of NH4C1.
Exp. 4. Heat the delivery-tube supplying the ammonia gas by
the Bunsen flame, the hot gas will inflame at the end of the tube
when a light is applied.
The solution of ammonia is obtained by passing the
gas through a series of Woulff's bottles provided with
safety-tubes. It was formerly obtained by the distillation of stags' horns, hence the common name still retained
of spirit of hartshorn. It is sometimes called the volatile
alkali. The salts of ammonia are supposed to be built
up like those of potassium and sodium, by supposing the
existence of a monad radical having the composition
NH4 as in NH4Cl given for ammonic chloride in the




SULPHUR.                  125
equation at the commencement of this chapter, and in
the chapter on nitrogen. This is similar to KC1 and
NaCl. The oxide of this body, which has been called
Ammonium, would be (NH4)20, and its hydrate, like
potash Klo, would be NH4Ho, which would be the
symbol for solution of ammonia or ammonic hydrate.
The abbreviation Am is used for this radical NH4 by
Dr Frankland, hence the three bodies named above
would be AmCl, Am2O, and AmHo.
Exp. 5. Make some sodium amalgam, by gently heating a little
mercury in an evaporating dish, and carefully putting some bits of
the metal sodium into it. The sodium inflames as it amalgamates
with the mercury. Make a strong solution of ammonic chloride
and pour upon it. The mass swells up, and common salt NaCl
is formed in the solution, the hypothetical NH4 amalgamates with
the mercury. It speedily decomposes, and nothing but mercury
is left.
The salts of ammonia or Ammonium are obtained by
adding the acids to the hydrate; it must be done carefully, particularly in the case of sulphuric acid.
AmHo + HC1    = AmCl    + OH2
AmHo + NOHo = N02Amo + OH2
AmHo + SOHo2 = SO2Amo2 + 20H2
CHAPTER XIX.
SULPHUR AND SULPHIDES-SULPHURETTED HYDROGEN.
97. Sulphur SV1 is a hexad element. It is found mixed
with earthy matter in Sicily, and also crystallised in cavities. It also exists in combination with metals as sulphides (FeS2 and Cu2S, etc.), and with oxygen and metals
as sulphates. The sulphur of commerce is obtained by
distilling (sublimation) the crude sulphur, the vapours
being conveyed into a chamber of brickwork, on the
walls of which they condense as " flowers of sulphur." If
the walls be hot, the sulphur melts and trickles down




126              PRACTICAL CHEMISTRY.
into wooden moulds in the floor, forming roll sulphur or
brimstone.   When the sulphides of iron and copper
(pyrites) are roasted,'the sulphur sublimes, and the
oxygen of the air converts them into oxides and sulphates.
Exp. 1. Heat a bit of galena (lead ore PbS) on charcoal before
the blowpipe, the sulphur sublimes and burns with a blue flame.
If the bead of lead obtained be heated in the oxidising flame, a
yellow incrustation will appear on the charcoal.
Exp. 2. Powder some iron pyrites (FeS2) and put it in a hard
glass tube closed at one end-or a hard test-tube. Heat it over
the Bunsen flame, covering the open end with the thumb. The
sulphide will be decomposed, and brownish drops of sulphur will
condense on the cool part of the tube.
SFeS2 = FesS + S2
Sulphur is a brittle yellow   solid, without taste or
smell.  It melts at 115~C, forming a yellow liquid; at a
higher temperature it becomes brown and viscid, becoming more liquid at 240~0, when it inflames if exposed to
the air.  At 440~ it boils, retaining its brown colour.
At a temperature of 1000~0 the vapour of sulphur occupies three times the volume it does just above the boiling
point; sulphur vapour at 1000~C being thirty-two times
the weight of an equal bulk of H. at the same temperature. Hence its atomic weight. Sulphur is hence a
hexad at the boiling point, but at 1000~ a dyad.
Sulphur is insoluble in water, but soluble in carbonic
disulphide CS2, and also in turpentine. It is also soluble
in potassic and calcic hydrates, potassic and calcic sulphide being formed. HC1 added to the latter precipitates
the sulphur as a white powder-milk of sulphur.
Exp. 3. Hold a bit of roll brimstone in the hand, it crackles
from the unequal expansion of the interior and exterior. Hold it
over the flame of a spirit-lamp, pieces fly off.
Exp. 4. Heat some sulphur in a Florence flask, the changes
mentioned in a previous paragraph will be seen, vapours being
given off which condense in the neck of the flask. Whilst in the
viscid condition, pour it out of the flask into water round an inverted funnel. Translucent strings, in a plastic condition, may
be taken out of the water and moulded like wax.
Exp. 5. Melt about a quarter of a pound of sulphur in a Cornish




SULPHUR.                       127
crucible on a clear fire. Cover it with a bit of tile before it has
all melted, or it will inflame, combining with the oxygen of the
air to form SO2. When it has all melted, take it off the fire with
a pair of crucible tongs; let it cool, and when a crust has formed
over the surface, make a hole in it and pour out the liquid sulphur.
Beautiful prismatic crystals will form in the interior. When
the crucible is quite cold, break it with a hammer and they will
be seen better
Exp. 6. Dissolve some flowers of sulphur in carbonic disulphide
(CS2); or turpentine, if the latter unpleasant smelling liquid is
not at hand; in either case keeping away from a light. Pour
the solution into an evaporating dish to evaporate slowly. Crystals
of a totally different shape -octahedrons-like double pyramids,
will separate.
As sulphur crystallises in two different forms, it is
said to be dimorphous.      The crystals obtained from
fusion, however, become opaque, and break up into
octahedrons in a few   days.    The plastic variety also
returns to the ordinary yellow kind, but while in its
plastic brown state it is insoluble in CS2.    In consequence of these differences, sulphur is said to exist in
three allotropic states.
Sulphur combines with the metals, forming sulphides,
which are similar in their composition to the oxides.
The metals in the form of leaf or fine wire burn in sulphur vapour.
Exp. 7. Melt a little more sulphur in the flask used in Exp. 4,
or in a large test-tube. Keep the vapours given off hot, by letting
a flame impinge on the upper part of the flask or tube. Attach a
bit of Dutch metal to a wire, and plunge it in the heated vapour;
it will take fire, cupric sulphide CuS, being formed. Other metals
in the state of leaf or foil may be substituted, or a bundle of fine
iron or copper wire.
Exp. 8. Shoot some iron filings into the flask of melted sulphur,
ferrous sulphide FeS will be formed. This compound is used in
the making of sulphuretted hydrogen. It is made by putting
lumps of iron into a crucible containing melted sulphur, an atom
of Fe only combining with one atom of sulphur; both act as
dyads.
98. Sulphuretted hydrogen SH2 (H - S - H.)
Sulphur can be made to unite directly with hydrogen,
but the compound SHs is usually obtained by the action




128              PRACTICAL CHEMISTRY.
of HI1 or SO2Ho2 upon ferrous sulphide FeS just mentioned, or by the action of HOC on antimonious sulphide
Sb2S3 at a gentle heat.
FeS  + 2HC1 = FeC1l     + SH2
FeS + SO2Ho2 = SOFeo" + SH2
Sb2S3 + 6HC1 = 2SbC13 + 3SH2
Exp. 9. Break some ferrous sulphide into small pieces, and put
it into the hydrogen apparatus; or, if a stink-closet be at hand,
keep a bottle for the purpose. Cover it with water, and pour
in some HC1; a gas having an offensive odour like rotten eggs
comes off. It is rather soluble in cold water, and should therefore
be collected in jars over warm water.
Exp. 10. Leave a little water in one of the jars, and shake it
up with the gas; the hand will be sucked in, showing that the
water has dissolved.
Put a blue litmus paper in the solution, it will be reddened,
showing the gas to have acid properties. It is sometimes called
hydrosulphuric acid. Keep the solution for future experiments.
Exp. 11. Inflame a jar of the gas, and hold a dry glass over it;
water and sulphurous anhydride will be produced.
Or, burn a jet of the gas previously dried by passing it through
a tube containing chloride of calcium. (See Exp. 9, Chap. VIII.)
Exp. 12. Graduate the explosion tube into five parts. Fill it
with two parts sulphuretted hydrogen * and three of oxygen. Bring
the mouth of the tube to a flame, the mixed gases will explode
violently, water and sulphurous anhydride being produced.
2SH2 + 302 = 2SO2 + 20H2
Exp. 13. Prepare a cylinder of chlorine, and bring it over an
equal-sized cylinder of SH2. Remove the glass plates, and let the
gases mix. The SH2 will be decomposed by C1, which combines
with the hydrogen to form HC1, sulphur being deposited round
the sides of the jar. (The latter is easily cleansed with potash.)
The experiment may be varied by adding chlorine water to a
solution of SH2t.
Exp. 14. Prepare a jar of sulphurous anhydride (see next chapter, Exp. 1), and bring it over a similar sized jar of SH2. The
gases will decompose each other, after the following equation4SH2 + 2SO2 = 40H2 + 3S2
Exp. 15. Pass SH2 from the delivery-tube, to which a bit of
flexible tube is attached through solutions of the following salts* The smell of sulphuretted hydrogen is readily destroyed by
burning sulphur.
+ The generation of a little chlorine speedily destroys the odour
of SH, in a room.




COMPOUNDS OF SULPHUR.            129
using a fresh bit of glass tube at the extremity, in each case, and
note the results, viz.:Sulphate of copper, plumbic acetate, arsenious anhydride, tartar
emetic (tartrate of antimony), sulphates of zinc and chromium and
ferric chloride.
The solution of the gas will do instead of the gas
itself. The solution, however, on exposure to the air,
loses its smell, water being formed by the oxidation of
the hydrogen, and sulphur being deposited.
Sulphuretted hydrogen is used in Analytical Chemistry,
to separate metals into groups by precipitation, mostly
as sulphides. The sulphides which are insoluble in water
may be precipitated from their ordinary aqueous solations; those insoluble in acids form acid solutions also;
but those which are soluble in acids must first be made
alkaline by the addition of ammonia. The sulphides of
K, Na, Ba, Sr, Ca, and Mg, being soluble, cannot be precipitated by sulphuretted hydrogen.
CHAPTER XX.
COMPOUNDS OF SULPHUR WITH OXYGEN AND HYDROXYL.
99. THERE are two compounds of sulphur with oxygen,
sulphurous anhydride  = S=0 or SO2, and sulphuric
anhydride  = S = 0 or S03.
0
These bodies added to water form two very important
compounds, sulphurous and sulphuric acids.
Sulphurous anhydride SO2 has been already prepared
by burning sulphur in oxygen, and as a secondary
product in many instances. It is a gaseous body. Its
weight compared with H. and air would be found thus:
S+02
32 + 32  64
32 + 3   = 64=32, its volume weight.
2     2
And 32   14 -47 = 221 times the weight of air.
24 E               I




130              PRACTICAL CHE!ISTRY,
It is usually prepared by heating copper or mercury
with sulphuric acid, the acid being deoxidised, gaseous
SO2 being evolved, water and sulphates of the metals
being also formed.
2S02Ho2 + Cu = S02Cuo" + 20H2 + SO2
Exp. 1. into a flask put some copper clippings and concentrated
sulphuric acid. Heat gently over a sand-bath, and a gas with the
odour of burning sulphur will be given off. It is very soluble in
water, and must therefore be collected over mercury or by downward displacement. A blue litmus will be reddened at the opening where the delivery-tube enters, as the gas has acid properties.
Collect several jars of the gas.
Exp. 2. Immerse a taper in a jar of'^s^<,.     the gas, it will be extinguished, and the
gas does not inflame.
~    (          tV!  Exp. 3. If a jar of the gas has been
collected over mercury, let it stand upright in the bath supported by a clip of
the retort stand.  Pour some water,
coloured with litmus, on the mercury,
and then raise the jar out of the mercury
into the water. The gas will dissolve
very rapidly. Water dissolves about 40
times its volume of the gas.
A solution of the gas may be made by
Fig. 42.       passing the gas into cold water till no
more is absorbed.
Exp. 4. Put a moistened bunch of violets into a jar of SO2, they
will be bleached, but the colour will be restored if they be dipped
into a weak solution of acid. Straw plait, wool, and silk are
bleached by exposing them to the vapours of burning sulphur, as
chlorine would injure such fabrics.
Infusion of rose leaves may be used, and the colour be restored
by dilute sulphurid or hydrochloric acids.
Exp. 5. Pass a stream of SO2 into a test-tube, surrounded by a
freezing mixture, -crushed ice, or snow, and salt. The gas will be
condensed into a colourless liquid.
The solution of the gas in Exp. 3, produces sulphurous
acid, SOHo2, and this, upon being cooled to the freezing
point, deposits white crystals. The gas when passed into
solutions of metallic hydrates forms two classes of salts,
called sulphites.  Sulphurous acid has the same effect.
NaHo + S02 = SOHoki(o, or NaHo,+ SOHo, = SOHoKo + OH2
and 2 NaHo + S0= SOKo2, or 2Nato + SOHo2 = SONao2 + 2IO2




COMPOUNDS OF SULPHUR.                131
100. Sulphuric acid. This most important acid may be
prepared in the following ways. Its preparation on a
large scale in leaden chambers may be passed over in an
elementary treatise.
Exp. 6. Expose some of the solution of SO2 i.e. SOHo2 to the
air; it will absorb oxygen, and be converted into sulphuric acid.
This may be tested by adding a solution of baric nitrate to a
freshly made solution of S02; very little white pp. will be produced.
Added to that which has been exposed to the air for several hours,
a dense white pp. of baric sulphate will be obtained.
Exp. 7. Boil some flowers of sulphur with nitric acid. The
sulphur will be oxidised at the expense of the nitric acid, and
sulphuric acid will be obtained. When cold, the liquid will not
dissolve copper, but when heated will be again deoxidised with
evolution of SO2.
Exp. 8. Heat liquid SOHo2 with nitric acid, the same result.
Sulphuric acid may be considered as made up of a
body called sulphuric anhydride SO3 and water, or of
sulphurous anhydride S02 and hydroxyl Ho2.
S03+ OH2 = S02Ho2, or S0 + Ho = S02Ho2
Sulphuric anhydride may be obtained by heating Nordhausen sulphuric acid, and condensing the vapours in a
flask surrounded by a freezing mixture; or, by passing
SO2 and oxygen over ignited spongy polatinum as in the
following:Exp. 9. Fit up a three-necked Woulff's bottle, so that a stream
of SO2 shall pass in by one tube, oxygen by a second, and let the
third neck be connected with a bit of combustion tube containing
a small quantity of spongy platinum. The gases will only mix
in the Woulff's bottle, but when the platinum is heated, the
mixed gases which condense in it enter into combination, and
vapours of sulphuric anhydride will pass out. If sufficient quantity
be obtained in white crystalline needles, they may be allowed to
pass into a test-tube containing water, which they will do with a
hissing noise, forming sulphuric acid.
Exp. 10. Shake up a mixture of sulphurous acid (solution of
802) with a solution of hydroxyl mentioned on page 100. Sulphuric
acid will be obtained. Test as in Exp. 6.
Exp. 11. Into a three-necked Woulff's bottle containing hot
water, pass a stream of nitric oxide and oxygen gas, and as the red
vapours appear, a stream of SO2. The N202 will be converted
into N20,, which will be again deoxidised by the SO2, and the
resulting compound will be dissolved by the stream, and form a
solution of sulphuric acid.




132             PRACTICAL CHEMISTRY.
Sulphuric acid forms salts called sulphates, by the displacement of the whole or part of the hydroxyl, by a
metallic radical. They are also formed by the action of
the acid on metallic carbonates. The acid chars organic
substances-abstracting the elements of water, and leaving the carbon.
Exp. 12. Make a strong solution of loaf-sugar in a beaker, and
pour concentrated sulphuric acid into it. A dense black mass
will froth up, and most likely overflow the vessel, which should
be placed in a dish.
If sulphur be boiled with a solution of sodic sulphite,
a salt called sodic hyposulphite SSONao2 is formed.
This is supposed to contain hyposulphurous acid SSOHo2,
which decomposes on the addition of dilute sulphuric
acid.
Exp. 13. Make a solution of sodic hyposulphite (used by photographers for dissolving the excess of silver salt), and add dilute
sUlphuric acid; S02 will be evolved, which may be detected by its
odour, and yellow sulphur will be deposited.
Exp. 14. Add dilute sulphuric or hydrochloric acid to sodic
sulphite, SO, will be evolved; but no sulphur will be deposited.
The student will now be able to understand the various
"Modes of chemical action." *    A few examples will
be given, and other similar cases should be sought out.
Chemical change takes place1. When elements or compounds combine directly with
each other.
S   + 0, = SO
N20,  + 02  = N204
NHs + HC1 = NH4C1
2. When compounds are split up into their elements,
or into less complex compounds.
OAg,     =Ag, +    0NONHO = N, + 20HF
NO,2NH10 = ON2 + 20H1
* See "Frankland's Lecture Notes," and Valentin's "Practical
Chemistry."




MODES OF CHEMICAL ACTION.           133
3. When one element or group of elements displaces
another element or group of elements.
2HC1   + K2= 2KC1     + H2
SO2Cuo' + Fe = SO2Feo" + Cu
PbA    + Zn = ZnA     + Pb
4. When elements or groups of elements in one body
are exchanged for other elements or groups of elements
in another body.
CuCI,   + SH,    = CuS    + 2HC1
CuC]2   + 2AmHo = CulHo   + 2AmCl
N2Bao + SO2Ho = -S02Bao" + 2NOHo
COCao" + 2HC1   = CaCI2   + OH2 + C02
5. When the elements of a compound are re-arranged,
as in the conversion of starch into sugar.  Numerous
instances occur in ORGANIC CHEMISTRY.








QUESTIONS
REQUIRING A PRACTICAL KNOWLEDGE OF
CHEMISTRY.
1. The following metals are heated in the Bunsen flame:Magnesium, platinum, zinc, sodium, copper; what is the effect
upon each, and what products would be formed?
2. When sodium is thrown into water, what takes place?
3. Describe an experiment to show the difference between a
mechanical mixture and a chemical compound.
4. What is the effect of heat upon manganic oxide, potassic
chlorate, ammonic chloride, ammonic nitrate, phosphorus, and
sulphur respectively?
5. What is the action of HC1 on the metals Zn, Fe, and Mg?
Express the reactions in equations, and draw graphic formulae of
the products formed.
6. You have given to you zinc, sulphuric acid, caustic, potash,
and water, and are required to prepare hydrogen from these
materials by two distinct processes; state how you would proceed, and show by an equation the chemical changes in each
case. (Exam. 1869).
7. I have two cylindrical jars of hydrogen; I hold one of them
mouth upwards, and the other mouth downwards. At the expiration of half a minute I plunge a lighted taper into each jar;
describe exactly what you would expect to take place in each
case. (Exam. 1872).
8. You have given to you some potassic chlorate (chlorate of
potash) and black oxide of manganese, and are required to make
and collect oxygen from these materials. Describe minutely how
you would do it, and make a sketch of the apparatus which you
would employ. What are the chief properties of oxygen?
(Question set, 1872, for those who wished to show a good knowledge of laboratory practice.)
9. What compounds can be formed from the following elements:-Oxygen, hydrogen, chlorine? and how?
10. What elements can be obtained from hydrochloric acid,
ammonia, and water? Say how you would obtain them in each
case.
11. When hydrogen is burnt in chlorine, what is produced?
Suppose it were burnt in air what product is formed?
12. I mix together chlorine and hydrogen, and expose the mixture to sunlight; what happens?  At the termination of the




136                   QUESTIONS.
experiment I add ammonia to the product. What is the name
and formula of the compound formed? (Exam. 1871).
13. If you had given to you some common salt and sulphuric
acid, and were required to fill a glass jar with HC1, describe how
you would do it, and give a sketch of the apparatus you would
employ. (Exam. 1872).
14. What is the action of sulphuric acid upon copper, sodic
chloride, and manganic oxide respectively when assisted by heat?
If the two latter are acted upon together what then takes
place?
15. If a mixture of manganic oxide (peroxide of manganese)
and hydrochloric acid be heated, what chemical change takes
place? Give the name and properties of the gas which is evolved.
(Exam. 1869).
16. An electric spark is passed through a mixture containing
120cc of hydrogen and 60cc of oxygen. How would you arrange
the experiment so as to show the gaseous condensation?
17. What is the action of the electric current upon water,
solutions of HC1 and NH3? State minutely how you would perform the experiments to show the results.
18. How would you prepare a solution of hydrochloric acid?
19. How would you prove the solubility of hydrochloric acid,
ammonia, and carbonic anhydride gases?
20. If I agitate with pure water a mixture of hydrogen, nitrogen, carbonic anhydride, and hydrochloric acid gases, what effect
will be produced? (Exam. 1872).
21. Steam and chlorine are passed through a porcelain tube,
heated to redness in a furnace, what takes place? Give equations to show the reaction.
22. You are required to make oxygen from chlorine and water.
Describe exactly how you will do it, and give a sketch of the
apparatus which you propose to employ. (Exam. 1871).
23. How is potassic chlorate usually prepared? Explain fully
the various steps in the process.
24. A piece of borax, a bit of chalk, and some nitre, are respectively heated upon charcoal before the blowpipe flame; what
takes place in each case?
25. You have some mercury, a glass flask, and a piece of hard
glass tube, and are required to make pure oxygen gas, how will
you do it? (Exam. 1869).
26. A stream of CO2 is passed into the following:-Distilled
water, lime water, ammonia solution, and baric peroxide suspended
in water; what takes place in each case?
27. How would you prepare boric acid from borax? What is
the action of boric acid (BHo,) on sodic carbonate?
28. When nitric acid is poured upon copper, how does the
action differ from a simple solution?




QUESTIONS.                    137
29. You have some ammonic carbonate (carbonate of ammonia)
and nitric acid, and are required to make and collect laughing
gas from these materials; how would you do it? Describe
minutely the apparatusyou would employ, and make a sketch of
it. What are the chief properties of laughing gas?
(Question set, 1871, to show good knowledge of laboratory
practice.)
30. You have given to you some sulphur, water, and nitric
acid; describe how you would make sulphuric acid from these
materials. (Exam. 1871).
31. State exactly how you would prepare nitrogen, nitric
oxide, and ammonia. Give equations. (Exam. 1869).
32. How is carbonic oxide usually prepared? Give a sketch
of the apparatus you would employ, and the reactions in the
process.
33. When carbonic oxide burns in air, what product is formed?
Iow would you test the properties of the gas and product?
34. When sulphuretted hydrogen is burnt in air, what products are formed? How would you prove their formation?
35. What is the action of dilute sulphuric acid upon sodic
sulphite, and also upon sodic hyposulphite?
36. Describe some experiments to show "the modes of chemical
action."




138              CHEMICAL APPARATUS.
APPARATUS AND MATERIALS
REQUIRED TO PERFORM THE EXPERIMENTS IN THE BOOK.
A.-LIST OF APPARATUS RECOMMENDED BY THE SCIENCE AND
ART DEPARTMENT FOR EACH STUDENT.
s. d.
Conical Brass Blowpipe, 2s, or Black Japanned,  -   0 8
6 inches Platinum Wire,   -                       06
Platinum Foil, 2 in. long, 1 in. wide,  -  -  -  - 1 0
Test-tube Stand, 24 holes,  -  -  -2 0
18 Test Tubes, 6 in. x 3 in.,  -  -  -  -  -   - 1 6
12,,     5x,    -        -0 —             - 08
2 Boiling Tubes (large Test Tubes, 8 x 1j),  -  -  0 4
2 Test Tube Brushes,  - 
Set of 3 Beakers,  -  -   -   -1 0
German Flasks, 1 of each, 2 oz., 4 oz., 8 oz.,'16 oz., 30 oz., 1 9
Berlin Porcelain Crucible, 1~ in. diameter,  -  -  0 4
Evaporating Dishes, 23 in. and 31 in. diameter,  - - 011
Funnels, one of each, 1 in., 2 in., and 3 in. diameter, - 0 10
English Filter Papers, 2 pkts. of 100, 23 in. and 4a in. dia. 0 10
Iron Retort Stand, 7s., or smaller one, -  -  -   3 6
Wire Gauze, 2 pieces, 5 in. sq.,  - -  -          0 4
Tin Plate Sand Bath, 5 in. diameter,  -  -  -     0 4
6 Watch Glasses, -   -0-                             6
l Ib. Soft Glass Tube, - to I in. diameter,  -  -  0 8
lb. Combustion Tube, a",  - -- 06
~ lb. Glass Rod, -3" bore,  -                        3
2 feet Black Caoutchouc Tube, |" bore, -     -  --  1 4
2feet,,,,,             -   -   - 0 8
Thistle Funnel,  -       -        — 03
3 dozen Assorted Corks, -  -    -              - 14
Woulfe's Bottle, 2 necks, i pint size,  -  -  -   1 0
Stoppered German Retort, 2 oz.,            -      0 8
Set of 3 Cork Borers, 3g, ~, and a, with iron rod, -  - 1 0
Triangular File and Handle, -  -  -                 8
5-inch Round File and Handle,-                    0 9
Bunsen's Gas Burner, with Blowpipe Jet, Star Support,
Chimney, and Rose Burner, -  -   -   -      3 6
Iron Crucible Tongs,              - - 
4-inch Porcelain Mortar and Pestle,  -       -  -  1 0
Books of Test Papers, Blue and Red Litmus, etc.,  - 0 6
Solution of Cobaltous Nitrate, 1 oz. in Stoppered Bottle, 0 7,  Argentic,,     oz.,,            0 6
Platinic Chloride, i oz.,,         - 1 9
1 Pint Methylated Alcohol in Bottle,  -    -   - 1 6
Glass Spirit Lamp, 4 oz. capacity, -  -  -  -  - 1 0
Deal Box, to contain the Set of Apparatus,  -  -  2 0




CHEMICAL APPARATUS.                139
B.-OTHER CHEMICAL APPARATUS REQUIRED FOR USE OF A
CLASS.
s. d.
3 Cylindrical Gas Tubes, 6" x 14",                2 0
1 Deflagrating Jar, -                                0
1,,       stoppered 10 oz.,  -   -   -      1 3
Cap and Spoon (extra spoon 6d.), -  -  -          1 0
Explosion Tube (or, Soda Water Bottle),  -  -   -1 6
2 Chloride of Calcium Tubes,  -    -   -          10
Balloon of Goldbeater's Skin, -                 - 1 0
Clark's Retort,  -   -    -   -- 0 6
Glass Dishes (basins can be used by students) each 10d. to 2 0
Pneumatic Trough (Japanned Tin), 1 gallon 3s.; 2 gallon  5 0
* Mercury Trough, -                               1 9
* 4 lbs. Mercury for Trough, -  -  per lb. 2s. 6d. to 4 6
** Eudiometer, straight, graduated in c. c.  --  Cs. to 9 0
A Wooden Vice, ---- 2 6
A 3-necked Woulfe's Bottle, pint size, -  -  -  -1 6
A Nest of 3 Cornish Crucibles,  -  -   -    -     0 3
A Box of Scales and Weights,  -                   2 6
Maw's Set of Gramme Weights,  -                    1 0
Herepath's Blowpipe, to use with Bunsen's Burner,  -2 6
Half Round Rasp in Handle,           -            1 0
C. —ELECTRICAL APPARATUS NECESSARY TO PERFORM SOME OF
THE EXPERIMENTS.
s. d.
Pair of 6-inch Bar Magnets,  -  -  -2 6
5, 4-inch Cells Bunsen's Battery, complete,  -    22 0
2 V-Tubes on Stands, with Platinum Plates and Wires
(page 49),  --               -         each 6 6
Voltameter for Mixed Gases (fig. 17, page 50),  -  - 5 6
with 2 Tubes, for collecting Gases separately
(fig. 18, page 51),  --                      9 6
** Induction Coil,                              - 10 0
** Or, Electrophorus,                           - 5 6
D.-MATERIALS REQUIRED TO PERFORM THE EXPERIMENTS
FOR A CLASS OF STUDENTS.
s. d.
1 lb. Granulated Zinc,  -                         0 8
i lb. Oxygen Mixture, -   -1 0
1 lb. Black Oxide Manganese, -  -               -0 3
~ lb. Chlorate Potash,  -                         0 8
i oz. Mercuric Oxide,   - -   -                   03
4 lb. Copper Turnings, -                          06
4 lb. Ferrous Sulphide (Sulphide of Iron),  -  -  - 0 2
i lb. Chloride Calcium (for drying gases, in stoppered bottle), 0 3




140         CHEMICAL APPARATUS.
s. d.
l Ib. Sulphur,                      0  2
1 oz. Phosphorus,  -. -  -  -       4
1 oz. Metal Sodium,  -  -  -  -  -  -  -  1 0
i dr.,, Potassium, -  -            1 0
4 oz. Iodine,  -  -  -  -.        1  2
l Ib. Ammonia Alum, -  -— 0 2
2 oz. Chloride Ammonium, -          04
4 lb. Borax, -  -  -                0 5
i oz. Boracic Acid, -  -  -02
2 oz. Red Lead,  -  --— 0 1
1 oz. Acetate Lead,  -  -  -  -  -  -0  1
1 oz. Sulphate Zinc,  -  -  -       1  0
l Ib. Sulphate Soda (Glauber's Salts),  -  -  -  0  2
1 Ib. Sulphate Copper,              0 2
4 lb. Sulphate Iron,- -             0 2
Ilb. Nitre (Saltpetre, Nitrate Potash),  -  -  0  2
1 lb. Nitrate Soda (Cubic Nitre),  -  -  -  0  2
2 oz. Baric Chloride or Nitrate,  -  — 0  2
1 oz. Cupric Chloride,  -  -  -  -  -  -  -  0  3
1 oz. Cupric Oxide,  -  -  -  -  -  -  -  3
1 oz. Ferric Chloride,  -  -  -  -  -  -  0  6
i lb. Caustic Soda,-  -  -.         0 2
1 oz. Caustic Potash,  -  -  -  -  -  -  -0  3
4 oz. Peroxide Barium,  -  - — 0      3
i oz. Sodic Nitrite, -  - --        0 4
1 oz. Ammonic Nitrite,  -  -  -  -  -  -   3
2 oz. Ammonic Nitrate, -  --      - 05
1 oz. Oxalic Acid,  -  -  -  -  -  -  0  2
4 oz. Pyrogallic Acid, -            10
i oz. Ferrocyanide Potassium,  -  -  0 3
4 oz. Mercuric Chloride, -        - 0  2
4 oz. Iodide Potassium, -  ------ 1 0
1 oz. Metallic Antimony,  -  -  -  -  0  2
Leaf Gold and Dutch Metal, Book of each  -  -  - 2 0
1 lb. Common Hydrochloric Acid, -  -  -  -  - 0 2
1 lb.,,  Sulphuric,,  -  -  -  -  0  2
lb.,,  Nitric,,        - -     0  4
i lb. Ammonia Solution,,  - -     06
The last four, in Winchester pint stoppered bottles at Gd.
each; the other materials in 4 oz. Flint Glass wide-mouthed
stoppered bottles at 5s. 6d. per dozen, or common wide-mouthed
bottles for corking, at Is. or 2s. per dozen.
*** The Chemical Apparatus and Materials can be had of
M. JACKSON, 65 Barbican, London, E.C.; G. MASON, 39 Union
Street, Glasgow; or from the Publishers. The Electrical Apparatus of W. PETERS, Philosophical Instrument Maker, 36 Whiskin
Street, Clerkenwell, E.C., at the prices named.