LESSONS 
IN 
ELEMENTARY CHEMISTRY: 
INORGANIC AND ORGANIC. LESSONS 
I N 
Elementary Chemistry: 
INORGANIC AND ORGANIC. 
BY 
HENRY E. ROSCOE, B.A. F.R.S. 
PROFESSOR OF CHEMISTRY IN OWENS COLLEGE, MANCHESTER. 
WM. WOOD & CO., PUBLISHERS, 
NEW YORK: 
61 Walker St. 
1868. The New York Printing Company, 
8j, 83, and 85 Centre Street, 
New York. TABLE OF CONTENTS. 
Lesson Page 
I. Introduction i 
II. Oxygen and Hydrogen 9 
III. Physical Properties of Gases, Thermome- 
ter, etc 18 
IV. Chemical Compounds of Oxygen and Hy- 
drogen—Composition and Properties of 
Water 28 
V. Nitrogen and the Atmosphere 42 
VI. Compounds of Nitrogen and Oxygen—Dal- 
ton’s Atomic Theory—Nitric Acid ... 50 
VII. Nitrous Oxide—Nitric Oxide—Ammonia . . 57 
VIII. Carbon—Carbonic Dioxide 65 
IX. Carbonic Oxide—Coal Gas—Flame .... 75 
X. Chlorine—Hydrochloric Acid—Bleaching 
Powder 85 
XL Bromine—Iodine—Fluorine 95 
XII. Sulphur—Sulphuric Dioxide 102 
XIII. Sulphuric Trioxide—Sulphuric Acid . . . 108 
XIV. Selenium—Tellurium—Silicon—Boron . . 117 
XV. Phosphorus and its Compounds 125 
XVI. Arsenic—Atomicity of the Elements . . . 133 
XVII. The Metallic Elements—Introduction . . 140 
XVIII. The Principles of Crystallography . . . 149 
XIX. Metals of the Alkalies—Potash, Soda . . 155 
XX. Metals of the Alkaline Earths, and 
Earths—Glass—Porcelain 168 
XXL Magnesium—Zinc—Cadmium—Manganese . 177 
XXII. Iron and its Manufacture 184 
XXIII. Cobalt—Nickel—Chromium—Tin 191 
XXIV. Arsenic—Antimony—Lead 199 
XXV. Silver—Copper—Mercury—Platinum . . . 207 VI 
Contents. 
Lesson Page 
XXVI. Principles of SpectrujI Analysis and Solar 
Chemistry 219 
XXVII. Organic Chemistry—Introduction .... 227 
XXVIII. Determination of the Composition of Car- 
bon Compounds 236 
XXIX. The Monatomic Alcoholic Group .... 246 
XXX. Dicarbon, or Ethyl Series 253 
XXXI. Organic Ammonias 264 
XXXII. Group of Fatty Acids 270 
XXXIII. Diatomic Alcohols and Derivatives . . . 280 
XXXIV. Diatomic Acids and Derivatives 286 
XXXV. Cyanogen Compounds 295 
XXXVI. Triatomic Alcohols and their Derivatives 301 
XXXVII. Saccharine and Amylaceous Bodies . . . 308 
XXXVIII. Gums and Glucosides 315 
XXXIX. The Group of Aromatic Compounds . . . 319 
XL. Turpentines, Vegetable Alkaloids .... 328 
XLI. Albuminous Substances—Animal and Vege- 
table Chemistry 338 
Questions and Exercises 349 
lNDEX -375 PREFACE. 
In the following pages I have endeavored to arrange 
the most important facts and principles of Modern 
Chemistry in a plain but precise and scientific form, 
suited to the present requirements of elementary 
instruction. 
For the purpose of facilitating the attainment of 
that exactitude in the knowledge of the subject, 
without which the introduction of physical science 
into the school system is worse than useless, I have 
added a series of Exercises and Questions upon the 
Lessons. The pupil must learn to work out accu- 
rately both the numerical and descriptive examples, 
and the teacher may find it advisable to add large- 
ly to their number. Particular attention should be 
given to the calculation of the relations between 
the weights of gases, and their volumes measured 
under varying circumstances of temperature and 
pressure. 
The metric system of weights and measures, and 
the centigrade thermometric scale, are used through- 
out the work. viii 
Preface. 
I have much pleasure in thanking my friend and 
assistant, Mr, Schorlemmer, for the aid which he 
has given me, especially in revising the proofs ; and 
I have also to acknowledge the care and attention 
bestowed on the woodcuts by Mr. Dickes. 
H. E. R. 
MANCHESTER. 
For further information concerning the absolute 
weights of the gases than is given on p. 26, a para- 
graph in the Appendix, page 373, may be con- 
sulted. INTRODUCTION. 
LESSON I. 
By chemical actioti we signify that which occurs when two or 
more substances so act upon another as to produce a third 
substance differing altogether from the original ones in pro- 
perties ; or when one substance is brought under such con- 
ditions that it forms two or more bodies differing from the 
original one in properties. Thus, if powdered sulphur and 
fine copper filings be well mixed together, the color of the 
sulphur as well as that of the copper will disappear, and to 
the unaided eye the mixture presents a uniform greenish tint; 
by the help of the microscope, however, the particles of cop- 
per may be seen lying by the side of the particles of sulphur ; 
and we can wash away the lighter sulphur with water, leaving 
the heavier copper behind. Here no chemical action has 
occurred ; the sulphur and copper were only mechanically 
mixed. If we next gently heat some of the mixture we see 
that it soon begins to glow, and on examining the mass we 
notice that both the copper and the sulphur have disappeared 
as such, that they cannot be distinguished even by the most 
powerful microscope, and that in their place we have formed 
a black substance possessing properties entirely different 
from those possessed either by the copper or by the sulphur. 
Here a chemical change has occurred ; the copper and the 
sulphur are said to have combined chemically to form a com- 
pound, out of which these two substances can be regained in 
exactly the quantities used. In like manner when a candle 
burns in the air a chemical change is going on ; and although 
the candle gradually disappears, the materials of which it is 
made up are not destroyed or lost; they simply pass into a 2 
Elementary Chemistry. 
state in which they are invisible to our eyes, but their pres- 
ence may be ascertained by other means. Thus, if we burn 
a candle for a few minutes in a clean bottle filled with air, and 
afterwards pour in some clear lime-water, we shall notice that 
the liquid, which remains clear in pure air, becomes at once 
milky, showing the presence of an invisible gaseous body 
produced by the burning of the candle, which possesses pro- 
perties different from those of pure air. Although an ap- 
parent loss of matter occurs when a candle burns, it is easy 
to show by a simple experiment not only that this is not the 
case, but that on the contrary an increase of weight has oc- 
curred ; this increase is occasioned by the constituent parts 
of the tallow or wax having united chemically with an invisible 
gas (called oxygen) present in the air. For this purpose a 
piece of glass tubing f inch wide, and 10 inches long, is closed 
at each end with a cork ; through the upper cork a bent glass 
tube passes, whilst through the lower one several holes are 
bored, and into one of these a small taper is fastened. The 
upper half of the tube is filled with pieces of caustic soda, a 
grid of perforated zinc being fixed inside the tube to keep 
them in their place. The tube thus arranged is hung at the 
end of one arm of a pair of scales, and exactly counterpoised 
by weights placed in the pan on the other arm. The top of 
the tube is now connected, by means of a piece of vulcanised 
caoutchouc tubing, with a closed vessel filled with water and 
furnished with a stop-cock through which the water can flow 
out; on opening this stop-cock, as the water flows out, air 
passes in to supply its place, through the holes in the per- 
forated cork. This cork is then removed, the taper lighted, 
and the cork and taper quickly replaced ; after the candle has 
burnt for three or four minutes, the vulcanised tubing is dis- 
connected, and the glass tube allowed to hang freely. It is 
then seen that the weight of the tube is greater than it was 
before the candle was burnt, the pieces of caustic soda having 
absorbed the substances (carbonic acid and water) produced 
by the combination of the constituents of the taper (carbon 
and hydrogen) with the oxygen of the air. Elementary Chemistry. 
3 
By the careful examination of all the known cases of chem- 
ical action it has been satisfactorily proved thata loss of matter 
never takes place, that matter is indestructible, and that in 
chemical actions such as that going on in the burning of the 
candle, a change of state and not an annihilation of matter 
occurs. The truth of this first great principle in chemical 
science has been gradually demonstrated by finding that the 
weights of the substance acting chemically upon one another, 
always remain the same after as before the chemical changes 
have occurred. For determining very accurately the weight 
Fig. i. 
of substances, an instrument called the chemical balance is 
employed. Fig. I represents one form of chemical balance. 
It consists of a perforated brass beam (a a) vibrating about 
its centre, at which is fixed a triangular knife-edge of agate 
(C): this rests upon a horizontal agate plane attached to the 
upright brass pillar. To each end of the beam the light brass 
pans (be) are attached, each pan hanging on by an agate 
knife-edge to an agate plane fixed on the end of the beam at 
(d d). This mode of rest and support is to render the amount 
of friction as small as possible, and thus to insure delicacy in Elementary Chemistry. 
4 
the instrument. In order to prevent the agate edges from 
being spoilt by constant wear on the agate planes, the beam 
and the ends (d d) are supported by the brass arm (e e) when 
the balance is not in use, so that the agate surfaces do not 
touch; the beam and pans are released when required by 
turning the handle (f). The body to be weighed is placed in 
one pan, and weights added one by one to the other until the 
instrument is in equilibrium ; this is ascertained by the long 
pointer (g) vibrating to an equal distance on each side of the 
central mark. A balance such as that represented in the 
figure will turn with iV of a milligramme when loaded with 
too grammes (see p. 21 ), or will indicate the one-millionth 
part of the substance weighed. 
The aim of the chemist is to examine the properties of all 
substances with regard to their actions upon one another in 
producing bodies essentially differing from the originals. In 
order thoroughly to carry out his purpose he is obliged to 
resort to experiment, that is, he has to place the substances 
which he is examining under circumstances, perhaps not 
found in nature, which he can control and vary. Hence 
chemistry is called an experimental science. In thus in- 
vestigating all the materials within his reach, whether solid, 
liquid, or gaseous, whether contained in the earth, sea, or air, 
whether belonging to the animal or to the vegetable creation, 
the chemist finds himself obliged to divide substances into 
two great classes : (1) those which he is able to split up into 
two or more essentially different substances, and (2) those 
which he is unable thus to split up, and out of which nothing 
essentially different from the original substances has been 
obtained.1 To the first class the name of compound., to the 
second the name of elementary or simple substances has been 
given. Compound bodies are made up of two or more ele- 
mentary substances chemically combined with each other: 
thus sulphur and copper are elementary bodies—out of each 
of these nothing different from sulphur or copper can be ob- 
tained; whereas, when the two bodies are heated together, a 
compound is formed from which both of the original element- Elementary Chemistry. 
5 
ary constituents can at any time be prepared. Water is a 
compound body, it can be split up into two elementary gases, 
hydrogen and oxygen ; common salt, again, is a compound of 
a gas (chlorine) with a metal (sodium); and limestone, clay, 
sugar, and wax may serve as examples of compound bodies: 
whilst phosphorus, charcoal, iron, mercury, and gold may be 
mentioned as belonging to the class of simple substances. 
The following experiment well illustrates the decomposition 
of a compound into two simple substances. A small quantity 
of the red powder called mercuric oxide, is introduced into a 
test tube and heated in a gas flame ; when hot, the oxide 
gradually decomposes, a grey deposit of metallic mercury in 
small globules collects upon the cooler parts of the glass, 
whilst the tube becomes filled with colorless oxygen gas 
whose presence can be demonstrated by the rekindling of a 
glowing chip of wood plunged into the tube. On continuing 
the heat, the whole of the red powder is found to be split 
up into the two elements, mercury and oxygen, which together 
weigh exactly as much as the red oxide from which they were 
obtained. 
The elementary bodies, for the sake of convenience, are 
arbitrarily divided into two classes, the metals and the non- 
metals. In the first are placed elements such as gold, iron, 
lead, mercury, tin ; in the second, those elements which are 
gases at the ordinary temperature, such as oxygen, hydrogen, 
&c., together with some solid elements, as sulphur, charcoal,&c. 
The number of the metals is much larger than that of 
the non-metals ; we are acquainted with forty-nine metals, 
and with only fourteen non-metals. These sixty-three ele- 
ments constitute the material out of which the whole fabric of 
the science is built; every description of matter which has been 
examined is made up of these elements, either combined to- 
gether to form compounds, or in the uncombined or free state. 
The science of chemistry has for its aim the experimental 
examination of the properties of the elements and their com- 
pounds, and the investigation of the laws which regulate their 
combination one with another. The applications of the prin- 6 
Elementary Chemistry. 
ciples of chemical science to the arts and manufactures are 
of the highest importance and interest; they have exerted a 
most material influence upon the progress of civilization, and 
have greatly tended to the elevation and benefit of mankind ; 
the instances are innumerable in which altogether new 
branches of industry have sprung up from the happy applica- 
tion of simple chemical principles, and there is scarcely an 
article in common use in the production of which some appli- 
cation of chemistry has not proved of essential value. 
The following is a complete list of the elementary bodies 
known at present (1866). The names printed in large capitals, 
as BORON, are the non-metals, those in small capitals, as 
Aluminium, are the more commonly occurring metals, those 
in small type, as Cadmium, are the rarer metals : 
Names. Symbols. Combining' Weight. 
Aluminium A1 27-4 
Antimony Sb 122 
Arsenic As 75 
Barium Ba 137 
Bismuth Bi 210 
BORON ...... B 11 
BROMINE . . . . Br 80 
Cadmium Cd 112 
Caesium ...... Cs 133 
Calcium Ca 40 
CARBON C 12 
CHLORINE .... Cl 35-5 
Cerium Ce 92 
Chromium . .... Cr ..... . 52-5 
Cobalt Co 587 
Copper Cu 63-5. 
Didymium D 96 
Erbium E 
FLUORINE . . . . F 19 
Glucinum G1 9-3 
Gold Au 197 Elementary Chemistry. 
7 
Names. Symbols. Combining Weight. 
HYDROGEN . . . . H i 
Indium In 74 
IODINE I 127 
Iridium Ir . 198 
Iron Fe 56 
Lanthanum La 92 
Lead Pb 207 
Lithium Li 7 
Magnesium. .... Mg 24 
Manganese .... Mn 55 
Mercury Hg 200 
Molybdenum .... Mo 96 
Nickel Ni 587 
Niobium Nb 94-0 
NITROGEN . . . . N 14 
Osmium Os 199-2 
OXYGEN O 16 
Palladium Pd ..... . 106-6 
PHOSPHORUS . . . P 31 
Platinum Pt 197-5 
Potassium K 39-1 
Rhodium Rh 104-4 
Rubidium Rb 85-4 
Ruthenium Ru 104-4 
SELENIUM . . . . Se 79-5 
Silver A g 108 
SILICON Si 28 
Sodium Na 23 
Strontium Sr 87-5 
SULPHUR S 32 
Tantalum Ta 172-0 
TELLURIUM. . . . Te 129 
Thallium T1 204 
Thorium Th 1157 
Tin Sn 118 
Titanium Ti . . . . . 50 Elementary Chemistry. 
8 
Names. Symbols. Combining Weight 
Tungsten W 184 
Uranium U 120 
Vanadium V 137 
Yttrium Y 
Zinc Zn 65'2 
Zirconium Zr 89^6 
Some of these are very abundant and occur widely dis- 
tributed, whilst others have only been found in such minute 
quantities, and in such rare fragments, that their properties 
have not yet been satisfactorily examined. Thus, for instance, 
oxygen occurs throughout the air, sea, and solid earth, in such 
quantities as to make up nearly half the weight of our planet. 
Whereas the metals yttrium, erbium, indium, &c. have only 
as yet been met with in most minute quantities. 
The elements are distributed very irregularly throughout 
our planet: only four occur in the air, some thirty have been 
found in the sea; whilst all the known elements occur vari- 
ously dispersed in the solid mass of the earth. The following 
table, giving the composition by weight of the primary rocks, 
shows that the bulk of the earth’s solid body is made up of 
only eight elements, the remainder being found in much 
smaller quantities: 
Composition of the Earth's Solid Crust in 100 parts by weight. 
Oxygen . . . to 487 
Silicon . . . 22’8 „ 36-2 
Aluminium . . 9-9 „ 6-i 
Iron .... 9.9 „ 2-4 
Calcium .... 6-6 to 0-9 
Magnesium . . 27 „ o-i 
Sodium .... 2-4 „ 2^5 
Potassium ... 17 „ 3-1 
Doubtless other elements exist undiscovered in the earth 
in addition to the sixty-four now known, for we find that 
where, with the progress of science, new and more accurate 
methods of examining the composition of matter have been 
employed, the existence of new elements has frequently been 
brought to light; thus within the last four years, no less than 
four new elements have been discovered by the help of the 
new method of spectrum analysis {see p. 219). Whether any Elementary Chemistry. 
9 
of the bodies now termed elementary may, by the application 
of more powerful means than we at present possess, at some 
future time be split up into simpler constituents, is a question 
which we cannot answer with certainty. Judging, however, 
from precedent, we may consider the occurrence of such a 
thing as possible, or even likely; for the alkalies potash and 
soda were believed to be elements until the year 1808, when 
Sir H. Davy proved that they were in reality compounds. 
Our knowledge of the chemical composition of the heavenly 
bodies was restricted, until lately, to that gained from the 
examination of meteorites, in which no element has been 
found which is not known in the earth. Within the last few 
years the foundations of a solar and stellar chemistry have, 
however, been laid ; and we are now able to ascertain the 
presence of many well-known chemical substances in the sun 
and far distant fixed stars with as great exactitude and certainty 
as we are able to prove their presence in terrestrial matter 
{see p. 223). 
NON-METALLIC ELEMENTS 
Oxygen. Symbol O. Combining Proportion 16. De7isity 16. 
Oxygen is a colorless invisible gas, possessing neither taste 
nor smell. It exists in the free state in the atmosphere, of 
which it constitutes about one-fifth by bulk, whilst in com- 
bination with the other elements, it forms nearly half the 
weight of the solid earth, and eight-ninths by weight of water. 
Oxygen was discovered in the year 1774 by Priestley, and in- 
dependently in 1775 by Scheele. Lavoisier first clearly pointed 
out in 1778 the part played by oxygen, and explained the 
chemical changes that go on when bodies burn in the air. 
The birth of the modern science of chemistry may be dated 
from the discovery of oxygen. Oxygen gas can be prepared 
from the air, but it is more easily obtained from many com- 
pounds which contain it in large quantities. Priestley prepared 
LESSON II. 10 
Elementary Chemistry, 
oxygen by heating red mercuric oxide : this substance is 
made up of 200 parts by weight of mercury, and sixteen parts 
of oxygen ; when strongly heated, it is decomposed, yielding 
metallic mercury and oxygen gas. Oxygen can be more 
cheaply obtained by heating potassium chlorate (commonly 
called chlorate of potash), a white salt which yields on heating 
39-2 per cent, of its weight of this gas. In order to collect 
the oxygen thus given off, powdered potassium chlorate is 
placed in a small thin glass flask, furnished with a well-fitting 
cork, into which a bent tube is inserted. The lower end of 
the tube dips under the surface of water in a pneumatic 
trough, and the gas, on being evolved, bubbles out from the 
end of the tube, and is collected in jars or bottles filled with 
water, and placed with their mouths downwards in the trough. 
Fig. 2 shows the arrangement of the apparatus needed for 
Fig. 2. 
the preparation of oxygen gas. If a small quantity of manga- 
nese di-oxide (black oxide of manganese) be mixed with the 
potassium chlorate, the oxygen is given off from the chlorate 
at a much lower temperature, and thus the evolution of the 
gas is facilitated, but the manganese di-oxide undergoes no 
change whatever. All the elements, with the single exception 
of fluorine, combine with oxygen to form oxides. In this act 
of combination, which is termed oxidatio7i, heal is always, 
and light is frequently, given off. When bodies unite 
with oxygen, evolving light and heat, they are said to 
burn, or undergo combustion. All bodies which burn in the 
air, burn with increased brilliancy in oxygen gas ; and many 
substances such as iron, which do not readily burn in the air, Elementary Chemistry. 
may be made to do so in oxygen. A red-hot chip of wood, 
or a taper with glowing wick, is suddenly rekindled and bursts 
into flame when plunged into a jar of this gas. Sulphur, 
which in the air burns with a pale lambent flame, emits in 
oxygen a bright violet light; and a small piece of phosphorus, 
when inflamed and placed in oxygen, burns with a dazzling 
light. If the jars, in which these experiments have been per- 
formed, be afterwards examined, it is found that the sub- 
stances produced by combustion in oxygen possess acid char- 
acters ; they have the power of turning red certain vegetable 
blue coloring matters, such as litmus: owing to this fact, La- 
voisier gave to oxygen the name it bears (from 6|i)j, acid, ycvvdu, 
I produce). Fine iron wire can be easily burnt in oxygen by 
tipping the end with burning sulphur, and then plunging the 
iron thus tipped into a jar of the gas ; the oxide of iron, formed 
by the combustion, drops down in the molten state. 
Many other substances may be employed for the prepara- 
tion of oxygen ; thus, if large quantities of the gas are needed, 
manganese di-oxide (a substance of frequent occurrence in 
nature) may be heated to redness in an iron bottle ; 100 parts 
by weight of the oxide yield 12-3 by weight of oxygen. 
Another interesting decomposition by which oxygen is set 
free, is that effected by sunlight upon the carbonic acid gas 
contained in the air ; this is accomplished by the green color- 
ing matter of plants. Sunlight has the power, in presence of 
this green coloring matter, of decomposing carbonic acid ; the 
carbon is taken up by the plant for its growth, whilst the 
oxygen is set free, and is afterwards used by animals for the 
support of the process of respiration. In the act of inspiration 
(filling the lungs) animals breathe in the oxygen of the air, 
whilst in that of expiration (emptying the lungs) they 
breathe out carbonic acid gas. Hence oxygen is neces- 
sary to animal life, wherefore this gas was formerly termed 
vital air. The chemical change which oxygen effects upon 
the body of the animal is in fact identical with that which 
goes on when a piece of charcoal burns in the air or oxygen ; 
this may be rendered evident by a simple experiment. If Elementary Chemistry. 
12 
some clear limewater be poured into a bottle of oxygen in 
which charcoal has been burnt, the limewater will become 
milky, owing to the formation of a compound of lime and 
carbonic acid (called chalk), this acid being produced by the 
combustion; if the air contained in the lungs be next blown 
through a piece of glass tubing into some more clear lime- 
water, a turbidity (from the formation of chalk) will at once 
occur, proving that carbonic acid gas is given off from the 
lungs. This carbonic acid arises from the oxidation of the 
constituents of the body, and by this oxidation the heat of the 
body, which is greater than that of surrounding inanimate 
objects, is sustained. When this chemical process stops, the 
animal dies, and the temperature of the body sinks to that of 
the neighboring objects. Carbonic acid, nitrogen, and some 
other gases cause death when inhaled, because they do not 
contain free oxygen, and hence the process of oxidation in 
the body ceases. This cause of death is independent of any 
poisonous action of the gases. Other processes for preparing 
oxygen on a large scale will be mentioned in the lessons relat- 
ing to bleaching powder, sulphuric acid, and barium peroxide. 
When the composition of a substance is determined by 
splitting the compound into its elementary constituents, a 
chemical analysis of that substance is said to have been 
made : when the composition is ascertained by bringing the con- 
stituent parts together, we are said to determine the composi- 
tion by synthesis. If we analyze potassium chlorate we find 
that, from whatever source this salt may be derived, it always 
possesses the same unalterable composition. This is true of 
every definite chemical compound; indeed, were it not so, chem- 
istry as a science could not exist. Potassium chlorate is made 
up of three elementary bodies, chlorine, potassium, and oxy- 
gen combined together in the following proportions by weight 
Chlorine . . . parts by weight. 
Potassium . , 39’1 “ 
Oxygen ,. . . 48*0 “ 
Potassium Chlorate . i22-6 “ Elernentaiy Chemistry. 
13 
When this salt is heated, the whole of the oxygen comes 
off as gas; 122-6 parts yield 48 parts of oxygen, while 74-6 
parts of a white solid compound of chlorine and potassium, 
called potassium chloride, remain behind. Hence the weight 
of oxygen which can be obtained from any given weight of 
potassium chlorate, and vice versa, can be calculated. In 
order to express the composition of substances more con- 
veniently than can be done by writing the names of the 
elementary constituents at full length, chemists use a kind 
of short-hand, or symbolic language, some of the princi- 
ples of which must now be shortly explained. Instead of 
writing the whole name, the first letter or the first two letters 
of the name alone are employed to designate the element; 
sometimes using the English, sometimes the Latin or Greek 
name. Thus Cl stands for Chlorine, O for Oxygen, and K 
(from Kali, another name for Potash) for Potassium. 
These letters, however, signify more than this : they stand 
not only for the elements in question, but they all have certain 
numbers belonging to them which indicate the proportions by 
weight in which the several elements combine with each other. 
Thus Cl does not signify any weight of chlorine, but always 
exactly 35-5 parts by weight; K does not signify any weight 
of Potassium, but always 39-1 parts ; while O signifies always 
16 parts by weight of Oxygen. Hence it is evident that we 
may express not only the qualitative but also the quantita- 
tive chemical composition of potassium chlorate by the sym- 
bol KClOa, in which O3 means 3 x 16 parts of Oxygen. In 
like manner each of the 64 elements has its particular symbol 
and number attached, signifying the proportion by weight in 
which it combines {see Table, page 6). The reasons which 
have led Chemists to adopt these special numbers for the 
combining weights or proportions of the elements, and the 
laws which have been found to regulate their combination, 
will be explained as our stock of chemical facts gradually 
becomes larger. 
The density or weight of a given volume of oxygen, com- 
pared with that of the same volume of hydrogen, is found to Elementary Chemistry. 
be sixteen, hydrogen, as the lightest body known, being taken 
as the standard. The specific gravity of oxygen, compared 
with the weight of the same volume of air taken as the unit, 
is found to be 1-1056. One litre of oxygen gas at o° C, and 
under the pressure of 760 millimetres of mercury, weighs 
1-4298 grammes. 
Pure oxygen undergoes a remarkable modification when a 
series of electric discharges is passed through the gas : it thus 
attains more active properties ; it is able to set free iodine 
from potassium iodide, and to effect oxidations which common 
oxygen is unable to bring about. This allotropic modification 
of oxygen has been termed Ozone. If a series of electric dis- 
charges be passed through pure oxygen, the gas becomes 
diminished in volume by about one-twelfth, and is partly 
transformed into ozone. If any substance be present, such as 
potassium iodide, capable of absorbing the ozone as it is 
formed, the whole of the oxygen can be transformed into this 
active modification. The peculiar smell which is observed 
when an electrical machine is worked, is caused by the 
presence of ozone ; and if a paper, dipped in a solution of 
potassium iodide and starch paste, be held opposite a point on 
the conductor of the machine, the paper becomes blue, owing 
to the liberation of iodine and the formation of a blue com- 
pound of iodine and starch. Ozone can be obtained in several 
other ways; it is formed when a stick of phosphorus is 
allowed to hang in a bottle filled with moist air ; it is pro- 
duced in small quantities in the electrolytic decomposition of 
water (see p. 32); and it is formed by the action of strong 
sulphuric acid upon a salt called potassium permanganate. 
There has been a great deal of discussion respecting the 
nature and composition of ozone. It appears, however, to be 
proved that it is simply oxygen in a condensed form. 
Hydrogen. Symbol H. Combining Proportion 1. Density 1. 
Hydrogen is a colorless invisible gas, possessing neither 
taste nor smell; it is the lightest body known, being 14-47 
times lighter than air. It occurs free in small proportions in Elementary Chemistry. 
15 
certain volcanic gases, but it is found in much larger quanti- 
ties, combined with oxygen to form water ({ISup, water, and 
ycwdu, I produce), and it is by the decomposition of water, 01 
of some other similar hydrogen compound, that the gas is 
always prepared. Hydrogen appears to have been first 
obtained by Paracelsus in the sixteenth century, but its pro- 
perties were first exactly studied by Cavendish in 1781. One- 
ninth of the weight of water consists of hydrogen, and this gas 
can readily be obtained from it'by the action of certain metals, 
which decompose the water, combining with the oxygen to 
form a metallic oxide, and liberating the hydrogen as a gas. 
The metals of the alkalies, potassium and sodium, decompose 
water at the ordinary temperature of the air ; some other 
metals, as iron, are only able to do so at a red heat; whilst 
others, for instance silver and gold, are unable to decompose 
Fig. 3. 
water at all. When a small piece of potassium is thrown 
into water, an instantaneous decomposition of the water 
ensues, potassium oxide (potash) is formed, and the hydrogen 
of the water is liberated, so much heat being at the same time 
evolved, that the hydrogen takes fire and burns. If the potas- 
sium, or still better, sodium, be wrapped in a piece of wire 
gauze, and thus held in the water of the pneumatic trough, 
under the mouth of a cylinder, the hydrogen gas thus liberated Elementary Chemistry. 
16 
may be collected, and its properties examined. To prepare 
hydrogen by the action of red-hot iron on water, a wrought 
iron pipe, like a gun-barrel, filled with iron turnings, must be 
heated in a furnace, Fig. 3, and steam from a small flask or 
boiler, passed over the red-hot metal through the tube ; 
hydrogen gas is given off, and oxide of iron left in the tube. 
The most convenient process of preparing pure hydrogen in 
quantity depends upon a property possessed by those metals, 
such as iron or zinc, which decompose water at a red heat, 
namely, that these metals are able to evolve hydrogen from 
water at the ordinary temperature of'the air if a dilute acid be 
present. For the purpose of thus obtaining hydrogen, a flask 
or bottle is provided with a cork and tube as represented in 
Fig. 4, some zinc clippings are introduced, and a mixture of 
Fig. 4. 
one part of sulphuric acid and eight parts of water poured in 
through the tube funnel. After a few minutes a rapid effer- 
vescence commences, and the evolved gas is collected over 
water in bottles or cylinders as in the case of oxygen. Care 
must, however, be taken that all the air is expelled from the 
flask before the hydrogen is collected; this is easily ascer- Elementary Chemistry. 
tained to be the case by filling a test tube with the gas, and 
trying whether it burns quietly when a lighted candle is 
brought to the mouth of the tube held downwards. Hydrogen 
burns in the air when a light is brought to it with a very 
slightly luminous, although extremely hot flame ; and in the 
process the hydrogen combines with the oxygen of the air, 
forming water. The production of water by the combustion 
of hydrogen in the air may easily be shown by bringing a 
bright dry glass over the flame of hydrogen issuing from a fine 
jet, as in Fig. 5 ; the glass becomes at once dimmed, owing to 
17 
Fig. 5. 
the condensation of water in small drops upon the cold dry 
surface. A number of these drops can be collected, and, upon 
examination, are found to consist of pure water. Hydrogen 
does not support the combustion of a candle, nor the life of 
an animal. If a burning taper is pushed up into a cylinder 
of this gas, held with its mouth downwards, the hydrogen 
burns at the mouth of the jar while the taper is extinguished ; 
it can, however, be relit by the flame at the mouth. Hydro- 
gen can be poured from one vessel to another in the air; but 
as it is lighter than air it must be poured upwards. The 
specific gravity of hydrogen, when air is taken as the unit, is 
found to be 0x1693; but for several reasons we shall find it Elementary Chemistry. 
more convenient to take hydrogen itself as our unit, and com- 
pare the weight of the same volumes of other gases with 
hydrogen instead of air. One litre of hydrogen gas at o° C. 
and 760 mm. pressure weighs 0-08936 gramme. Free hydro- 
gen, like oxygen, has never been obtained in the liquid or 
solid state. 
If we concentrate by boiling the liquid remaining in the 
flask after the evolution of the hydrogen, we find that white 
crystals separate out when the liquid cools ; these consist of 
zinc sulphate. A given weight of zinc (with sulphuric acid 
and water) can always be made to produce a certain weight 
of hydrogen, and a certain weight of zinc sulphate will always 
be formed. It is found by experiment that 2 parts by weight 
of hydrogen can be obtained by dissolving 65-2 parts of zinc 
with the formation of 161-2 parts of zinc sulphate. 
The pupil must carefully work out the examples and exer- 
cises given for each Lesson at the end of the book, and thus 
test the accuracy of his knowledge. 
LESSON III. 
Physical Properties of Gases, &c. 
It becomes now of importance to ascertain not merely the 
weights of oxygen and hydrogen capable of being evolved by 
using given weights of potassium chlorate or zinc, but likewise 
the volume of each gas thus obtained. Before we can enter 
into these calculations there are several important preliminary 
subjects, with the principles of which we must make ourselves 
acquainted. 
The first of these is the metric, or French decimal system 
of weights and measures ; the second is the mode of measur- 
ing temperature, and the construction and use of thermome- 
ters, together with the laws regulating the expansion of gases 
by heat; whilst the third relates to the measurement of at- 
mospheric pressure by means of the barometer, and the laws Elementary Chemistry. 
19 
regulating the changes which variations of pressure produce 
in the volumes of gases. 
Metric System of Weights and Measures. 
There are several distinct advantages to be gained by the 
adoption of this system, the chief of which is that the system 
is throughout a decimal one, and hence all calculations for re- 
duction, such as occur in our old measures (from pennyweights 
to tons, or from inches to miles, for instance), are avoided. A 
second important consideration which renders our use of this 
system advisable, is that it is now generally adopted by men of 
science in all countries. The starting point of this system is 
the establishment of a unit of length called a metre, equal to 
rather more than our yard (more exactly, 39’37 English 
inches). This metre, like all other standards of length, is an 
arbitrary length : a standard metre was prepared, and of this 
copies are made for use.* 
The metre is divided into tenths, hundredths, and thou- 
sandths ; these parts are termed respectively, decimetres, cen- 
timetres, and millimetres. The multiples of the metre, tens, 
hundreds, and thousands, are called decametres, hectometres, 
and kilometres. The measures of area, or square measure, 
and those of capacity, or cubic measure, are easily obtained ; 
we have square metres and square deci-, centi-, and milli-me- 
tres ; we have also cubic metres, and cubic deci-, centi-, and 
* When the metre was first made, it was intended to give it a length which should 
have some reference to the earth’s circumference, and a standard was made which 
had the length of the part of the distance from the equator to the pole, as 
10,000,000 
measured by the French geometricians. Subsequent investigations have, however, 
proved that the measurement of the earth’s circumference then made is not quite 
correct, and hence the metre turns out to be not quite (although very nearly) the 
part of the true distance of the pole from the equator. The value of the 
10,000,000 
metric system does not at all depend upon this relation between the earth’s circum- 
ference and the metre. The metre is the length of the bar of metal carefully pre- 
served in Paris, from which copies have been taken for use. 20 
Elementary Chemistry. 
milli-metres ; and we have the square and cubic measures de- 
rived from the multiples of the metre in the same way. 
io decimetres i metre. 
100 centimetres 
1.000 millimetres ,. “ 
zoo square decimetres i square metre. 
10,000 “ centimetres .... “ 
1.000. “ millimetres .... 
1.000 cubic decimetres . . . . i cubic metre. 
1.000. “ centimetres .... 
1,000,000,000 “ millimetres .... 
The measure on the margin is one decimetre in 
length ; it contains 10 centimetres and 100 millime- 
tres. For the sake of simplicity the word litre is 
used to signify I cubic decimetre (rather less than an 
English quart). 
The French philosophers who arranged this metric 
system wished to have a simple relation between the 
measure of volume and that of weight, and they de- 
termined to take as their unit of weight the weight 
of I cubic centimetre of pure water of the tempera- 
ture of 40 Centigrade, weighed at Paris. This weight 
is termed a gramme. It is divided like the metre 
into tenths, hundredths, and thousandths, called re- 
spectively deci-, centi-, and milli-gramme ; whilst to 
the tens, hundreds, and thousands of grammes the 
names deca-, hecta-, and kilo-gramme are given. (A 
table showing the relation between the weights and 
measures of the metric system and those commonly 
in use in this country is given in the Appendix.) 
Measurement of Temperature.—Thermometers. 
Measurements of changes of temperature are always effect- 
ed by ascertaining the expansion or contraction which bodies 
undergo by alteration of temperature. For this purpose 
liquids are generally used, as solids expand too little and Elementary Chemistry. 
21 
gases too much to be convenient indicators. Mercury and 
alcohol are the liquids commonly employed, especially the 
former, because its rate of expansion is nearly uniform, and 
because the range of temperature which can be measured by 
a mercurial thermometer is large, this metal boiling at a very 
high temperature, and freezing at a comparatively low one. 
Alcohol is used when very low temperatures have to be mea- 
sured, as this liquid has never yet been frozen. Air thermo- 
meters are only used in very delicate experiments in physics. 
In order to prepare a mercurial thermometer a straight piece 
of glass tubing, having a bore as uniform as possible through- 
out its whole length, is taken, and a bulb blown upon the end. 
This bulb, together with the whole of the tube, is then filled 
with mercury, and heated up to the highest temperature which 
the instrument is required to measure ; the open end of the 
tube is then completely closed, whilst full of mercury, by melt- 
ing the glass before the blowpipe. The thermometer thus 
prepared requires graduating, in order that its indications 
may be compared with those of any other. This graduation is 
effected : i. By plunging the bulb and stem in finely-pow- 
dered and melting ice, and marking on the stem the point 
where the mercury stands. 2. By immersing the bulb and 
stem in the steam given off from water boiling in a metallic 
vessel, and marking off the point where the mercury then 
stands. Care must be taken during this last experiment that 
the height of the barometer be observed ; the reasons for this 
precaution will be explained further on. Having obtained 
these two fixed points, it is easy to adapt a scale to the ther- 
mometer. Three scales, each of which is capable of being 
expressed in terms of the others, are at present in use : 1. 
The Centigrade scale. 2. Fahrenheit's scale. 3. Reaumur's 
scale. In the Centigrade scale (which we shall adopt, it being 
the one almost universally employed in scientific works, and 
in general use on the Continent) the space between these two 
points—called respectively the freezing and boiling points— 
is divided into ico equal parts, each of which is called a de- 
gree : the Zero of the scale is placed at the freezing point, so 22 
Elementary Chemistry. 
that the boiling point is ioo°. These divisions are continued 
above and below the boiling and freezing points, and those 
below this latter are characterized by a minus sign, thus, —x° 
—2°, etc. Fahrenheit divided the same space into 180 equal 
parts, each of which is called a degree Fahrenheit ; he did 
not, however, commence his scale at the freezing point, as he 
erroneously thought that he had obtained the greatest possi- 
ble degree of cold by making a mixture of snow and salt; the 
temperature of this mixture he found to be 32 of his degrees 
below freezing point; he therefore called the freezing point 
320. In Fahrenheit’s scale, minus num- 
bers are employed to denote those tem- 
peratures below the Zero of his scale ; 
this scale is the one in common use in 
England, but is the most inconvenient 
one which we could adopt. Reaumur’s 
scale (used in Russia and Sweden) re- 
sembles the Centigrade scale, except 
that the space between the freezing and 
boiling points is divided in 80 equal 
points ; so that water boils at 8o° Reau- 
mur. The connection between these 
three scales is seen at a glance by refer- 
ence to fig. 6. The relation between the 
degrees of Fahrenheit, Centigrade, and 
Reaumur, is expressed by the numbers 9, 5, 4. In converting 
from degrees Fahrenheit to Centigrade or Reaumur, we must 
remember first to subtract 32 and then reduce ; whilst, when 
passing from degrees Centigrade and Reaumur to Fahrenheit, 
we must add 32 after the multiplication and division is com- 
pleted. 
Fig. 6. 
If very exact measurements are required, several precau- 
tions must be taken in the graduation and use of thermometers ; 
thus, for instance, the tube must be calibrated—that is, the 
irregularities in the bore must be determined and allowed for, 
whilst any slight alteration in the position of the freezing 
point must from time to time be ascertained. Different raer- Elementary Chemistry. 
23 
curial thermometers often show slight differences in the indi- 
cations, owing to the unequal expansion of different kinds of 
glass, hence it is necessary in exact experiments to have re- 
course to the air thermometer. 
Expansion of Gases by Heat. 
Solid and liquid bodies expand much less for equal incre- 
ments of heat than gases ; they also all expand differently, 
whilst all gases expand alike, or very nearly so. The expansion 
of solids and liquids is a subject with which, in elementary 
chemistry, we have little to do, whilst a knowledge of the laws 
regulating the expansion of gases is of more immediate im- 
portance. It has been found by exact and laborious experi- 
ment that all gases expand part of their volume at o° C. 
for every increase in temperature of i° Centigrade : 
Thus 273 volumes of air or hydrogen at o° 
become 274 “ “ i° 
it 2° 
il 276 l< li 30 
or 273 + t “ “ t° 
The decimal fraction corresponding to 27a is o,oo3665 ; r 
volume of air at 0° C. becomes 1 ’003665 volumes when heated 
to i° C. This fraction is called the co-efficient of the expan- 
sion of gases* If we require to know the volume which 1,000 
cubic centimetres of hydrogen measured at o° C. will occupy 
when the temperature is raised to 20°, we must remember that 
the alteration in bulk takes place in the ratio of the numbers 
273 to 273 + 20. Hence we multiply 1,000 by 293 and divide 
by 273. If we require to know what the volume 1,000 cbc. 
* Regnault and Magnus have shown that hydrogen gas expands rather less than 
atmospheric air, whilst carbonic acid gas expands rather more than air. The coef- 
ficients of expansion from o° to too® obtained by these two renowned experimental- 
ists are as follows : 
Regnault. Magnus. 
Hydrogen .... o'366i4 °'36S56 
Carbonic acid . . . o'syogg C36909 24 
Elementary Chemistry. 
measured at 20° C. will occupy when the temperature sinks to 
o", we have to remember that the diminution in volume fol- 
lows the same law, and that, therefore, 293 vols. at 20° will 
become 273 vols. at o°. If we have 1,000 cbc. of gas at 20°, 
and desire to know the volume which it will occupy at 50°, we 
have in like manner to remember that 273 + 20, or 293 vols. 
at 200, become 273 + 50, or 323 vols., at 50° ; and then we can 
easily find the alteration in volume which the 1,000 cbc. of gas 
will undergo when heated from 20° to 50°. 
Relation of Volume of Gases to Pressure. 
When a gas is subjected to an increase of pressure, the 
volume of the gas becomes less ; and when the pressure is 
withdrawn, the gas immediately expands again, and occupies 
exactly the same volume which it did before the pressure was 
increased. Solid and liquid bodies cannot be compressed in 
the same way. Gases are hence known as compressible 
fluids, and liquids as incompressible fluids : liquids, however, 
really are compressible, but only to a very slight extent; like 
gases, they recover their original volume on removal of the 
pressure. The law representing the relation between the 
volumes of a gas and the pressures to which the gas is sub- 
jected, is a very simple one : it is termed Boyle's or Ma- 
j-iotte's Law, from the names of the discoverers : it states 
that the volume occupied by any gas is inversely proportional 
to the pressure to which it is subjected.. Thus, for instance, 
the volume x under pressure x becomes the volume 2 under 
the pressure the volume 3 under the pressure £, the 
volume under the pressure 2, and the volume i under the 
pressure 3, and so on.* For a description of the experimen- 
tal proof of this law, a work on Physics must be consulted. 
The instrument which serves to measure the pressure 
* This law, like many other physical laws, is only an approximation to the truth 
as ascertained by exact experiment. No gases obey the law exactly when high 
pressures are used, and many deviate perceptibly ; still, as these deviations are but 
very slight, we may assume, for the purpose of our calculations, the absolute truth 
«)f the law of Bovle, Elementary Chemistry. 
25 
exerted by the air is termed a barometer. (Fig. 7.) This in 
its simplest form consists of a straight glass tube, about 
800 mm. (33 inches) in length, closed at one end, and 
furnished with a millimetre scale. This tube is 
filled with dry mercury, and the open end 
placed downwards in a basin containing the 
same metal. It is then seen that the mercury 
sinks in the tube to a point about 760 mm. from 
the surface of the metal in the basin : it is sus- 
tained in this position by the pressure of the 
air. When this pressure becomes greater the 
height of the sustained column becomes greater; 
when it diminishes, the level of the mercury in 
the tube falls. All gases generated at the 
earth’s surface are subject to this pressure, 
and their volumes increase or diminish ac- 
cording to the above law, when the superin- 
cumbent pressure becomes less or greater. 
In estimating the volume of hydrogen which 
can be collected from a given weight of zinc and 
sulphuric acid, it is clear that we require to know not only the 
temperature at which the gas is collected, but also the atmosphe- 
ric pressure under which it is measured ; and in order to be able 
to compare the bulks of two gases, we must always compare 
them under like conditions of temperature and pressure. For 
this purpose we agree to compare all the volumes of gases at the 
standard temperature of o° C. and under the standard pres- 
sure of 760 millimetres of mercury. Suppose now that we 
desire to know what weight of potassium chlorate we need to 
take in order to fill with oxygen gas a gasholder having a 
capacity of 10 litres, the temperature of the room being 150 
C. and the barometer standing at 752 mm. We know that 
(1) 122'6 parts by weight of potassium chlorate yield 48 of 
oxygen ; (2) that a litre of oxygen at o° C. and 760 mm. 
weighs 1‘4298 grms. We must now ask what will 10 litres of 
oxygen weigh if measured at 150 C. and under the pressure 
of 752 mm. ? Now, 10 litres at o° and 760 mm. will become 
Fig. 7. Elementary Chemistry. 
26 
1 o x 760 x (2 73+_l_5) — j o. 66 r at 150 and 752 mm.; therefore, 
752x273 
if 10 litres at o° and 76o mm. weigh 14*298 grms. 10 litres at 
150 and 752 mm. will weigh 13*411 grms. Next we 
require to know how many grammes of chlorate will furnish 
this weight of oxygen ; as every 122*6 parts of chlorate yield 
I ">2 6 X 13 4.11 
48 parts of oxygen we shall need ——= 34*254 
48 
grms. of chlorate. In the same way we can calculate, for 
instance, the weight of zinc and sulphuric acid needed to in- 
flate a balloon of the capacity of 150 cubic metres with hydro- 
gen, when the thermometer stands at n° C. and the barome- 
ter at 763 mm. The student will do well to work out numer- 
ous examples of this kind, in order to familiarize himself with 
these methods of calculation (see Exercises at the end of the 
book). 
It may be as well here to mention a simple, mode of calcu- 
lating the absolute weight of a given volume of any gas at o° 
and 760 mm. depending upon the fact, which will become evi- 
dent as we proceed, that the densities of all the elements 
known in the gaseous state are identical with their combining 
weights* 
Thus the density and combining weight of oxygen are alike 
16 ; or, oxygen is 16 times heavier than hydrogen ; the densi- 
ty and combining weight of nitrogen are alike 14 ; or, nitro- 
gen is 14 times heavier than hydrogen ; the density of chlo- 
rine is 35*5, that of sulphur vapor 32, and so on. Remem- 
bering this fact, it is easy to calculate the absolute weight of a 
given volume—say one litre of these different gases—when 
we know that one litre of hydrogen at the standard pressure 
and temperature weighs 0*08936 grammes. Thus 1 litre of 
oxygen, under the same circumstances, weighs 
16x0.08936 = 1430 grms. 
* Two notable exceptions to this law occur in the case of phosphorus and arsenic, 
whose vapors possess a density twice as great as that requited to be in accordance 
with the above law, which holds good for all other gaseous elements. Elementary Chemistry. 
i litre of nitrogen weighs 14x0-08936 = 1-251 grms. 
„ chlorine „ 35-5 x 0-08936 = 3-172 „ 
„ sulphur vapor „ 32x0-08936 = 2-860 „ 
In the case of almost all compound gases, the density is one- 
half the combining weigh:.* 
T o 
Thus the density of water-gas, or steam, is __ or 9 ; that 
is, it is nine times heavier than hydrogen ; the density of 
hydrochloric acid is 1—? or 18.25 ; that of ammonia, 11 
2 2 
or 8.5; that of carbonic acid, H or 22. Hence the 
2 
weights of 1 litre of these compounds (estimated at o° C. and 
760 mm.) are as follows :— 
1 litre of steam weighs . , 9 x 0.08936 
„ ammonia „ . . 8.5x0-08936 
„ hydrochloric acid „ . . 18-25x0-08936 
„ carbonic acid „ . . 22 x 0-08936 
27 
Diffusion of Gases. 
Another physical property of gases is that of diffusion. 
Gases which, when mixed together, do not combine chemi- 
cally, have the power of becoming intimately mixed together, 
even when different in specific gravity, and when the heavier 
gas is placed at the bottom, and both remain at rest. This 
important property is called the diffusive power of gases. The 
rate at which gases diffuse varies greatly. Thus, a bottle 
filled with hydrogen lost 94.5 per cent, of this gas when left 
exposed to the air in the same time as that in which a bottle 
of carbonic acid lost only 47 per cent, of this gas in the same 
way. Gaseous diffusion goes on through the minute pores of 
certain solids, such as stucco, or thin plates of graphite ; the 
different diffusive rates of air and hydrogen may be well seen 
by fixing a thin piece of graphite on to one end of a glass 
* The exceptions to this law are mentioned under the several compounds. 28 
Elementary Chemistry. 
tube open at the other end, and filling this with hydrogen ; on 
plunging the open end into water a steady rise of this liquid 
in the tube is noticed, and after some time the whole of the 
hydrogen is found to have disappeared, and the tube to con- 
tain only pure air. Experiments made upon this subject have 
shown that the velocity of diffusion of different gases is in- 
versely proportional to the square roots of their densities ; 
thus 4 volumes of hydrogen will pass through the diaphragm 
in the same time that i volume of oxygen is able to do so, 
oxygen being sixteen times as heavy as hydrogen. This pro- 
perty of gases has an important bearing upon the atmosphere 
of towns and dwelling-rooms, which is kept pure to a great 
extent by this diffusive power of gases. 
Chemical Compounds of Oxygen and Hydrogen. 
LESSON IV. 
We are acquainted with two compounds of oxygen and 
hydrogen, namely:— 
(i.) Water or Hydric Oxide. Symbol H20. Combining 
Proportion 18, Density 9. 
(2.) Peroxide of Hydrogen or Hydric Peroxide. Symbol 
H202. Combining Proportion 34. 
Water, H20. When hydrogen burns in the air water is 
formed by the union of the former gas with oxygen. The dis- 
covery of the composition of water was made in 1781 by Mr. 
Cavendish, who showed that two volumes of hydrogen unite 
with one volume of oxygen to form water. In order to prove 
this, Cavendish made a mixture of these gases in this propor- 
tion by volume in a jar, and then allowed them to pass into a 
strong dry vessel (Fig. 8), from which the air had been pumped 
out. By means of two platinum wires melted through the 
glass (at b), an electric spark could be passed through the 
mixture of the two gases, causing their combination ; dew was 
then seen to be deposited upon the sides of the vessel, and, Elementary Chemistry. 
29 
when the stopcock was opened under water, this liquid rushed 
in, filling the whole space formerly occupied by the mixed 
gases. Cavendish weighed the glass before and after the ex- 
Fig. 8. 
periment, and knowing the weight of gases taken, he found 
that the weight of the water produced was the same as that 
of the gases which combined. Since the above-mentioned 
year, the exact composition of water has been made the sub- 
ject of careful synthetical experiment by many chemists, and 
the result has been to confirm by much more delicate methods 
this original conclusion. The most accurate of these methods 
of ascertaining the composition of water is a modification only 
of that originally used by Cavendish. We use for this pur- 
pose a long, accurately graduated, strong glass tube called a 
Eudiotneter (A, Fig. 9), open at one end and closed at the 
other, whilst through the glass at the top are melted two pla- 
tinum wires. This tube is first filled with mercury, and in- 
verted mouth downwards over a trough filled with this metal 
(Fig. 9). Hydrogen gas is now allowed to enter the tube, and 
the volume admitted measured (suppose equal to 100 vo- 
lumes) ; oxygen gas is next and the volume of the 
two mixed gases measured (suppose that 75 volumes of oxy- 
gen are added). In making this experiment, care must, how- 
ever, be taken that the tube is not more than half full of the 30 
Elementary Chemistry. 
gaseous mixture, as great heat is evolved by the combustion, 
and hence a sudden expansion of volume occurs, for which 
reason it is necessary to press down the open end of the tube 
upon a plate of caoutchouc placed under the mercury. An 
electric spark is now passed through the gas along the plati- 
num wires, when a flame is seen to pass down through the 
gas, showing that combination has occurred. As soon as the 
heat caused by the combustion has disappeared, the water 
produced will be deposited as dew upon the inside of the 
tube, and will then only take up about 2-0Vo part of the bulk 
which its constituent gases occupied, so that its volume may 
be neglected ; when the bottom of the eudiometer is opened 
the column of mercury in the tube rises, and we shall then 
find that only 25 volumes of gas remain, and this turns out 
to be pure oxygen. Thus we see that 100 volumes of hydrogen 
require exactly 50 volumes of oxygen for their complete com- 
Fig. 9. Elementary Chemistry. 
31 
bustion. By a modification of this experiment, it can be 
shown that the volume of the gaseous water formed, occupies 
exactly 100 volumes; or 2 volumes of hydrogen unite with I 
of oxygen to form 2 volumes of steam, hence the density of 
16 + 2 
steam, or weight of 1 volume is =9. The most strik- 
2 
ing method of demonstrating the composition of water analy- 
tically is by splitting it up into its constituent gases by means of 
a current of voltaic electricity. For this purpose we fill a glass 
vessel (Fig. 10) with water acidulated with sulphuric acid to 
enable it to conduct the electricity, and bring two test tubes 
filled with water and inverted into this vessel over two small 
platinum plates attached to wires of the same metal passing 
through the caoutchouc stopper at the bottom of the glass; 
on connecting these with the terminals of a battery of three 
Fig. 10. 
or four of Grove’s elements, an evolution of gas from each 
plate is noticed, that disengaged from the plate in connection 
with the platinum end of the battery is found to be pure oxy- 
gen, whilst that coming off from the other plate, connected 32 
Elementary Chemistry. 
with the zinc end of the battery, is pure hydrogen gas. If the 
two tubes be graduated it will be seen that the volume of the 
hydrogen is a very little more than double that of the oxygen, 
for owing to the oxygen being rather more soluble in water 
than hydrogen, we do not thus get quite the exact propor- 
tions. In order to collect the detonating mixed gases evolved 
by this electrolytic decomposition of water, 
an apparatus represented in Fig. n may 
be employed. 
Oxygen being 16 times as heavy as hy- 
drogen, and these gases combining to form 
water in the proportions by volume of one 
volume of the former to two of the latter, 
we now know that the proportions by 
weight in which these gases exist in water 
must be as 16 to 2. It is nevertheless most 
important that this calculation be verified by direct experi- 
ment. For this purpose use is made of the fact that copper 
oxide when heated alone, does not part with any of its oxygen, 
but when heated in the presence of hydrogen it parts with as 
much oxygen, as will, by combining with the hydrogen, form 
Fig. ii. 
Fig. i2. 
water, being itself wholly or partly reduced to metallic copper. 
If, therefore, we take a known weight of copper oxide, heat it, Elementary Chemistry. 
33 
and pass pure hydrogen over it until it has parted with all its 
oxygen, and if we collect and weigh all the water thus formed, 
and likewise weigh the remaining metallic copper, we shall 
have made a synthesis by weight of water. For the loss in 
weight of the copper oxide is the weight of oxygen which 
has combined with hydrogen to form water ; and the difference 
between this weight and that of the water formed, is the 
weight of the hydrogen thus combined. The arrangement 
originally used for this determination is represented in Fig. 12. 
The hydrogen is purified from any trace of arsenic, sulphur, 
and moisture which it may contain by passing through the 
U tubes, containing absorbent substances, and placed in a 
freezing mixture. Some only of these (A) are represented in 
the figure. The tube B, containing a very hygroscopic sub- 
stance, is weighed both before and after the experiment, and 
if no increase occurs, the dryness of the gas is insured. The 
gas then comes in a perfectly pure state into contact with the 
heated copper oxide contained in the bulb C. This first bulb, 
which is accurately weighed, is placed in connection with a 
second bulb D, in which the water formed by the reduction 
of the oxide collects ; any moisture which may escape con- 
densation in this bulb is retained in weighed drying tubes, E 
and F, containing fragments of pumice moistened with sul- 
phuric acid. Most careful experiments made according to 
this method, carried out with many precautions, which cannot 
here be detailed, have shown that SB'Sg parts of oxygen by 
weight unite with ini parts of hydrogen to form 100 parts 
of water. 
Free oxygen and hydrogen combine together, when a light 
is brought in contact with them, with so much force that a 
violent and dangerous explosion occurs from the sudden ex- 
pansion caused by the great heat evolved in combination. If 
we fill a strong soda-water bottle one-third full with oxygen 
and two-thirds with hydrogen, and then bring a flame to the 
mouth, the gases combine, producing a sudden detonation 
like the report of a pistol. Many fatal accidents have oc- 
curred to persons who have carelessly experimented with large Elementary Chemistry. 
34 
volumes of this explosive mixture. In order to exhibit the 
great heat evolved by the combination of the two gases the 
oxyhydrogen blowpipe is employed ; in this arrangement the 
gases are contained separately in two caoutchouc bags, being 
only brought together at the point at which the combination 
is desired, so that all danger of explosion is avoided. The 
flame thus produced is very slightly luminous, but its tem- 
perature is so high, that the most difficultly fusible metals, 
such as platinum, may be easily melted in it, whilst iron wire 
held in the flame burns with beautiful scintillations, forming 
an oxide of iron. 
Water exists in nature in three forms : in the solid form as 
ice, in the liquid state as water, and in the gaseous form as 
steam. At all temperatures between o° and 100° C. it takes 
the liquid form, and above ioo° it entirely assumes the gase- 
ous form (under the ordinary atmospheric pressure of 760 mm.). 
The melting point of ice is always found to be a constant 
temperature, and hence it is taken as the zero of the Centi- 
grade scale ; water may, however, under certain conditions, 
be cooled below o° C. without becoming solid ; still ice can 
never exist at a temperature above o° C. In passing from the 
solid to the liquid state water becomes reduced in volume, 
and on freezing, a sudden expansion (from 1 volume to 1 ‘099) 
takes place. That this expansion exerts an almost irresis- 
tible force is well illustrated by the splitting of rocks during 
the winter. Water penetrates into the cracks and crevices 
of the rocks, and on freezing widens these openings ; this 
process being repeated over and over again, the rock is ul- 
timately split into fragments. Hollow balls of thick cast-iron 
can thus easily be split in two by filling them with water and 
closing by a tightly fitting screw and then exposing them to a 
temperature below o° C. 
In the passage from solid ice to liquid water, we not only 
observe this alteration in bulk, but we notice that a very re- 
markable absorption, or disappearance of heat, occurs. This 
is rendered plain by the following simple experiment:—Let 
us take a kilogramme of water at the temperature o°, and Elementary Chemistry. 
35 
another kilogramme of water at 79° ; if we mix these, the 
temperature of the mixture will be the mean, or 390,5 ; if, 
however, we take 1 kilogramme of ice at 0° and mix it with a 
kilogramme of water at 790, we shall find that the whole of 
the ice is melted, but that the temperature of the resulting 2 
kilogrammes of water is exactly 0°; in other words, the 
whole of the heat contained in the hot water has just sufficed 
to melt the ice, but has not raised the temperature of the 
water thus produced. Hence we see that in passing from 
the solid to the liquid state a given weight of water takes up 
or renders latent just so much heat as would suffice to raise 
the temperature of the same weight of water through 790 C.; 
the latent heat of water is therefore said to be 79 thermal 
units—a thermal unit meaning the amount of heat reqtdred 
to raise a unit of water through 10 C. When water 
freezes, or becomes solid, this amount of heat which is neces- 
sary to keep the water in the liquid form, and is therefore well 
termed the heat of liquidity, is evolved, or rendered sensible. 
A similar disappearance of heat on passing from the solid to 
the liquid state, and a similar evolution of heat on passing 
from the liquid to the solid form, occurs with aH substances ; 
the amount of heat thus rendered latent or evolved varies, 
however, with the substance. A simple means of showing 
that heat is evolved on solidification consists in obtaining a 
saturated hot solution of Glauber’s salt (sodium sulphate), 
and allowing it to cool. Whilst it remains undisturbed, it 
retains the liquid form, but if agitated, it at once begins to 
crystallize, and in a few moments becomes a solid mass. If 
now a delicate thermometer be plunged into the salt while so- 
lidifying, a sudden rise of temperature will be noticed. Simi- 
larly water at rest may be cooled down below oc C. without 
solidifying, but if agitated, it at once solidifies, and the tem- 
perature of the whole mass instantly rises to 0° C. 
When water is heated from o° to 40, it is found to contract, 
thus forming a striking exception to the general law, that 
bodies expand when heated and contract on cooling; on cool- 
ing from 40 to o° it expands again : above 4°, however, it 36' 
Elementary Chemistry. 
follows this ordinary law, expanding when heated, and con- 
tracting when cooled. This peculiarity in the expansion and 
contraction of water may be expressed by saying that the 
point of maximum density of water is 40 C.; that is, a given 
bulk of water will at this temperature weigh more than at any 
other. Although the amount of contraction on heating from 
0° to 40 is but small (1 volume of water at 40 becoming 
1 +0'OOOI2 at 0°), it yet exerts a most important influence 
upon the economy of nature. If it were not for this appa- 
rently unimportant property, our climate would be perfectly 
arctic, and Europe would in all probability be as uninhabitable 
as Melville Island. In order better to understand what the 
state of things would be if water obeyed the ordinary laws 
of expansion by heat, we may perform the following experi- 
ment. Take a jar containing water at a temperature above 
40, place a thermometer at the top and another at the bottom 
of the liquid. Now bring the jar into a place where the tem- 
perature is below the freezing point, and observe the tem- 
perature at the top and bottom of the liquid as it cools. It 
will be seen that at first the upper thermometer always indi- 
cates a higher temperature than the lower one ; after a short 
time both thermometers mark 40 ; and as the water cools still 
further, it will be seen that the thermometer at the top always 
indicates a lower temperature than that shown by the one at 
the bottom ; hence we conclude that water above or below 
40 is lighter than water at 40. This cooling goes on till the 
temperature of the top layer of water sinks to o°, after which 
a crust of ice is formed ; but if the mass of the water be 
sufficiently large, the temperature of the water at the bottom 
is never reduced below 40. In nature precisely the same 
phenomenon occurs in the freezing of lakes and rivers ;* the 
surface-water is gradually cooled by cold winds, and thus 
becoming heavier, sinks, whilst lighter and warmer water 
rises to supply its place: this goes on till the temperature of 
the whole mass is reduced to 40, after which the surface-water 
* The point of maximum density of sea-water is considerably lower than that of 
fresh, and is in fact below o° C. Elementary Chemistry. 
37 
never sinks, however much it be cooled, as it is always lighter 
than the deeper water at 40. Hence ice is formed only at the 
top, the mass of water retaining the temperature of 4°. Had 
water become heavier as it is cooled down to the freezing 
point, a continual circulation would be kept up until the 
whole mass was cooled to o°, when solidification of the whole 
would ensue. Thus our lakes and rivers would be converted 
into solid masses of ice, which the summer’s warmth would 
be quite insufficient to melt thoroughly ; hence the climate 
of our now temperate zone might approach in severity that 
of the arctic regions. Sea-water does not freeze en masse, 
owing to the great depth of the ocean, which prevents the 
whole from ever being cooled down to the freezing point; 
similarly, in England, very deep lakes never freeze, as the 
temperature of the whole mass never gets reduced to 40 C. 
In passing from the liquid to the gaseous state, water 
exhibits several interesting and important phenomena. In 
the first place, when we heat water to ioo° C. it begins to 
boil, or enters hito ebullitionj that is, a rapid disengage- 
ment of water-gas, or steam, from the lower or most heated 
surface takes place : this is well seen when water is heated 
in a glass globe over a gas flame. In this passage from 
the liquid to the gaseous state, a large quantity of heat 
becomes latent, the temperature of the steam given off being 
the same as that of the boiling water, as, like all other bodies, 
water requires more heat for its existence as a gas than as a 
liquid. The amount of heat latent in steam is roughly ascer- 
tained by the following experiment. Into 1 kilog. of water at 
o°, steam from boiling water, having the temperature of 100*, 
is passed until the water boils ; it is then found that the whole 
weighs 1'187 kilogs. or o'iSy kilogs. of water in the form of 
steam at ioo°, have raised 1 kilog. of water from 0° to ioo°; 
or 1 kilog. of steam at ioo° would raise 5’36 kilogs. of ice-cold 
water through ioo°, or 536 killogs. through i°. Hence the 
latent heat of steam is said to be 536 thermal uiiits. 
Water, and even ice, constantly give off steam or aqueous 
vapor at all temperatures, when exposed to the air; thus we 33 
Elementary Chemistry. 
know that if a glass of water be left in a room for some days, 
the whole of the water will gradually evaporate. This power 
of water to rise in vapor at all temperatures is called the 
elastic force, or tension, of aqueous vapor; it may be 
measured, when a small quantity of water is placed above the 
mercury in a barometer, by the depression which the tension 
of the vapor thus given off is capable of exerting upon the 
mercurial column (as in Fig. 7). If we gradually heat the 
drops of water thus placed in the barometer, we shall notice 
that the column of mercury gradually sinks, and when the 
water is heated to the boiling point, the mercury in the baro- 
meter tube is found to stand at the same level as that in the 
trough, showing that the elastic force of the vapor at that 
temperature is equal to the atmospheric pressure. Hence 
water boils when the tension of its vapor is equal to the 
superincumbent atmospheric pressure. On the tops of moun- 
tains, where the atmospheric pressure is less than at the sea’s 
level, water boils at a temperature below ioo°; thus at Quito, 
where the mean height of the barometer is 527 mm., the boil- 
ing point of water is 99°’! ; that is, the tension of aqueous 
vapor at 90°-! is equal to the pressure exerted by a column 
of mercury 527 mm. high. Founded on this principle, an 
instrument has been constructed for determining heights by 
noticing the temperatures at which water boils. A simple 
experiment to illustrate this fact consists in boiling water in a 
globular flask, into the neck of which a stopcock is fitted : as 
soon as the air is expelled, the stopcock is closed, and the 
flask removed from the source of heat; the boiling then 
ceases ; but on immersing the flask in cold water, the ebulli- 
tion recommences briskly, owing to the reduction of the pres- 
sure consequent upon the condensation of the steam ; the 
tension of the vapor at the temperature of the water in the 
flask being greater than the diminished pressure. All other 
liquids obey a similar law respecting ebullition ; but as the 
tensions of their vapors are very different, their boiling 
points vary considerably. 
When steam is heated alone, it expands according to the Elementary Chemistry. 
39 
law previously given for permanent gases, but when water is 
present, and the experiment is performed in a closed vessel, 
the elastic force of the steam increases in a far more rapid 
ratio than the increase of temperature. The following table 
gives the tension of aqueous vapor, as determined by ex- 
periment, at different temperatures measured on the air 
thermometer. 
Tension of the Vapor of Water 
Temperature 
Centigrade. 
Tension in 
millimetres of 
mercury. 
Temperature 
Centigrade. 
Tension in 
atmospheres, 
1 atmosphere 
= 760 mm. of 
mercury. 
—20° 
0‘927 
100° 
I 
IO 
2-093 
II17 
I'S 
O 
4600 
I20"6 
2 
+ 5 
6-534 
127-8 
2-5 
IO 
9>i6S 
133-9 
3 
IS 
12-699 
1440 
4 
20 
17-391 
159-2 
6 
3° 
3I-548 
170-8 
8 
40 
54-906 
180-3 
10 
5° 
91-982 
213-0 
20 
6o 
148-791 
188-4 
12 
70 
233-093 
195-5 
14 
So 
354-280 
201-9 
16 
9° 
525-450 
207-7 
18 
IOO 
760-000 
213-0 
20 
2247 
25 
We now see why the barometric height must be noticed in 
graduating a thermometer (Page 21); if the height differ from 
760 mm. the temperature of the water boiling under that pres- 
sure will not be quite ioo° C. A metal vessel is here em- 
ployed, because it is found that water does not always boil at 
ioo° in glass vessels, even though the atmospheric pressure 
be 760 mm., owing to some molecular action analogous to 
cohesion between the glass and water. 40 
Elementary Chemistry, 
Water and ice, when seen in large masses, are found to 
possess a blue color; this is well seen in the glaciers and 
lakes of Switzerland. In order to obtain pure water the 
chemist is obliged to distil river or spring-water (that is, to 
boil the water and collect the water formed by the condensa- 
tion of the steam thus produced), as all such water contains 
more or less solid matter in solution derived from the surface 
of the earth over which the water flows ; this dissolved solid 
matter is left behind on boiling off the water. Solid matter in 
suspension can be got rid of by the simple process offiltration 
through paper, sand, &c. An arrangement for distillation 
used in laboratories is seen in Fig. 13, Rain-water is the 
Fig. 13. 
purest form of water occurring in nature, but even this con- 
tains impurities derived from the dust, &c. in the air, and no 
sooner does it touch the earth’s surface than it dissolves some 
of the materials with which it comes in contact, and accord- 
ing to the nature of the ground over which it passes becomes 
more or less impure. All fresh water on the earth’s surface 
has been derived from the ocean by a vast process of distilla- 
tion, having been deposited in the form of rain or snow from 
the atmosphere. Elementary Chemistry. 
Water is the most general solvent for chemical substances 
with which we are acquainted. Most salts are soluble to a 
greater or less extent in water, and are deposited again in 
crystals when the water is evaporated ; we are unacquainted 
with any simple general law regulating the quantities of solids 
taken up by water; in most cases the solubility is greater in 
hot than in cold water. Water is also contained in the solid 
state in combination as water of crystallization in many salts ; 
when this water is driven off by heat, the crystal falls to pow- 
der. Gases also dissolve in water in quantities varying with 
the nature of the gas, the temperature, and the pressure to 
which the gas is subjected. It is solely in consequence of the 
presence of oxygen derived from the air dissolved in the water 
of lakes, rivers, and seas, that fish are enabled to keep up their 
respiration ; as the water passes through their gills the oxygen 
is taken up to purify their blood. 
Hydric Peroxide, II2 02. This is a substance which does 
not occur in nature, but is artificially prepared by acting on 
barium peroxide Ba 02 with hydrochloric acid H2 CI2 ; an ex- 
change takes place between the barium and hydrogen, giving 
rise to hydric peroxide and barium chloride. Thus 
Ba I Qa 
Cl2 I H2 
It has received the name of oxygenated water, as it easily de- 
composes into oxygen and water: it is found to contain twice 
as much oxygen as water does, consisting of 2 parts by weight 
of hydrogen combined with 32 of oxygen ; hence, if we repre- 
sent water by the symbol H20, hydric peroxide will be writ- 
ten H2 02. 
Hydric peroxide acts as a powerful bleaching agent, owing 
to the ease with which it parts with half its oxygen, thus ox- 
idizing the coloring matters ; but owing to the difficulty at- 
tending its preparation, it has not been applied to this pur- 
pose on a large scale. 
In addition to water and hydric peroxide, we are acquainted 
with no compounds of oxygen and hydrogen. 42 
Elementary Chemistry. 
LESSON V. 
Nitrogen. Symbol N Combining P7'oportion 14. 
Density 14. 
Nitrogen exists in the free state in the air, of which it con- 
stitutes four-fifths by bulk ; it occurs combined in the bodies 
of plants and animals in various chemical compounds, such 
as nitre, whence the gas derives its name (generator of nitre). 
It is best obtained from the air by taking away the oxygen 
with which it is mixed ; for this purpose we may burn a piece 
of phosphorus in a bell-jar filled with air, the mouth of which 
is placed in a vessel full of water. White fumes of a com- 
pound of phosphorus and oxygen, phosphoric pentoxide, at 
first fill the jar, but these soon subside and dissolve in the 
water, leaving the nitrogen in a nearly pure state. One-fifth 
of the original volume of the air, consisting of oxygen, will 
have disappeared. Nitrogen may also be prepared by pass- 
ing air over red-hot metallic copper, which combines with the 
oxygen, forming a solid compound, and leaving the gaseous 
nitrogen in a pure state. Nitrogen is also formed when a cur- 
rent of chlorine is passed through an excess of a solution of 
ammonia; nitrogen gas is evolved, and sal-ammoniac remains 
behind in solution. If the chlorine be present in excess, a 
most dangerous and explosive compound is formed. Nitro- 
gen is a colorless and tasteless inodorous gas slightly lighter 
than air (specific gravity o-972, air being 1.0). It does not 
combine readily with bodies, and is a very inert substance, 
neither supporting combustion nor animal life, nor burning it- 
self : it has, however, no poisonous properties, and animals 
plunged into a jar of this gas die simply of suffocation from 
the want of oxygen. Nitrogen can be made to unite with both 
oxygen and hydrogen ; when combined with the latter it forms 
a powerful alkaline base, aimnonia, and united with both ele- 
ments it forms a strong acid, nitric acid. Elementary Chemistry. 
43 
The Atmosphere is the gaseous envelope encircling the 
earth ; and it constitutes the ocean of air at the bottom of 
which we live. We become aware of the existence of the air 
when we move rapidly, and experience the resistance offered 
to the passage of our bodies, and also when the air is in mo- 
tion giving rise to a wind. We notice the pressure of the at- 
mosphere if we withdraw the air from beneath the hand by a 
powerful airpump, for we then find that the hand is pressed 
down with a force equal to ro33 kilogs. on a square centi- 
metre, or nearly 15 lbs. on every square inch. The total at- 
mospheric pressure which the human body has to support 
hence amounts to several tons, but this pressure is not felt un- 
der ordinary circumstances, because the pressure is exerted 
equally in every direction. The instrument used for measur- 
ing the pressure of the air is termed a Barometer {see Fig. 7, 
p. 25), and the average pressure at the sea level is equal to 
that exerted by a column of mercury 760 mm. high. The air 
being elastic and having weight, it is clear that the lower lay- 
ers of air must be more compressed than those above them, 
and hence the density of the air must vary at different heights 
above the sea level. The density of the air being thus de- 
pendent on the pressure to which it is subjected, the higher 
strata of air become extremely rarified, and it is hence diffi- 
cult to say exactly whereabouts the air ceases, but it appears 
that the limit of the atmosphere is about 45 miles from the 
level of the sea. If the whole atmosphere were of the same 
density throughout as it is at the earth’s surface, it would only 
reach to a height of a little less than 5 miles above the sea 
level. The weight of one litre of dry air at o° and under 760 
mm. of pressure is i’2932 grammes. 
Respecting the chemical composition of the atmosphere, we 
have to remark, in the first place, that the air is a mixture, and 
not a chemical compound of its constituent gases, although, as 
we shall see, these occur throughout the atmosphere in almost 
unvarying proportions. The grounds for coming to this con- 
The Atmosphere. 44 
Elementary Chemistry. 
elusion are, first, if we bring oxygen and nitrogen together in 
the proportions in which they are found in air, no elevation of 
temperature or alteration in bulk occurs (as is invariably the 
case when gases combine), and yet the mixture acts in every 
way like air; secondly, that the relative quantities of the two 
gases present are, not those of their combining weights, nor 
of any simple multiples of these weights, and that although 
in general the proportions of the two gases are constant, yet 
instances not unfrequently occur in which this ratio is differ- 
ent from the ordinary one. The most convincing proof, how- 
ever, that air is not a chemical compound, is derived from an 
experiment upon the solubility of air in water: when air is 
shaken up with a small quantity of water, some of the air is 
dissolved by the water; thus dissolved air is easily expelled 
again from the wrater by boiling, and on analysis this expelled 
air is found to consist of oxygen and nitrogen in the relative 
proportions of I and r87. Had the air been a chemical 
compound, it would be impossible to decompose it by simply 
shaking it up with water ; the compound would then have dis- 
solved as a whole, and on examination of the air expelled by 
boiling, it would have been found to consist of oxygen and 
nitrogen in the same proportions as in the original air, viz. as 
1 to 4. This experiment shows, therefore, that the air is only 
a mixture, a larger proportion of oxygen being dissolved than 
corresponds to that contained in the atmosphere, owing to 
this gas being more soluble in water than nitrogen. 
There are many ways of determining the amounts of oxy- 
gen and nitrogen contained in the air, the best of these being 
by the eudiometer j* by means of which the composition by 
volume is ascertained. For this purpose the same arrange- 
ment is employed as that used in the eudiometric synthesis 
of water. (Fig. 14.) A quantity of air sufficient to fill the 
tube about one-sixth full is introduced into the eudiometer 
previously filled with mercury ; the volume of this air is then 
accurately ascertained by reading off with a telescope the 
* From rr'diof, good, and pirpov, a measure : a measure of the goodness or 
healthiness of the air, that is, of the quantity of oxygen which it contains. Elementary Chemistry. 
45 
number of the millimetre divisions on the tube to which the 
mercury reaches, whilst the height of the column of mercury 
in the tube above the trough, together with that of the ba- 
rometer, and the temperature of the air, are also read off. 
Such a quantity of pure hydrogen gas is now added as is more 
than sufficient to combine with all the oxygen present; and 
the volume of this gas, and the pressure exerted upon it, are 
then determined as before. An electric spark is now passed 
through the mixture, care having been taken to prevent any 
escape of gas by pressing the open end of the eudiometer 
against a sheet of caoutchouc under the mercury in the 
Fig. 14. 
trough. After the explosion the volume is again determined 
as before, and is found to be less than that before the explo- 
sion, the whole of the oxygen and part of the hydrogen having 
combined to form water ; the diminution, therefore, repre- 
sents exactly the volumes of these gases which have united. 
We know, however, from our previous experiments upon the 
composition of water, that 2 vols. of hydrogen always unite 
with 1 vol. of oxygen to form water; hence one-third of Elementary Chemistry. 
4 6 
the diminution in volume must represent the oxygen which 
has disappeared, and, therefore, the volume of oxygen con- 
tained in the air taken. An example may make this clearer. 
Suppose the volume of air taken amounted to 100 vols. and 
that after the addition of hydrogen the volume of the mixture 
was 150 vols. ; after the explosion 87 vols. were found to 
6* 
remain, that js, 63 vols. had disappeared; then 21 
3 
will be the volume of oxygen contained in 100 vols. of air. 
Analyses of air collected in various parts of the globe thus 
made with the greatest care have shown that the relative 
quantities of oxygen and nitrogen remain the same, or very 
nearly the same, from whatever region the air may have been 
taken. So that whether the air be derived from the tropics, 
or the arctic seas, from the bottom of the deepest mine or from 
an elevation of 20,000 feet above the earth’s surface, it con- 
tains from 20'9 to 21 vols. of oxygen per cent 
When we know the composition of air by volume and the 
relative densities of the two constituent gases (14 for nitrogen 
and 16 for oxygen), we can calculate its composition by 
weight; we thus find that in 100 grms. of air 23-i6 grms. of 
oxygen are mixed with 76 84 grms. of nitrogen. It is im- 
portant to control this calculation by experiment; for this 
purpose a large glass globe furnished with a stopcock is ren- 
dered vacuous by the airpump and then weighed ; a tube of 
hard glass filled with copper turnings and also furnished with 
stopcocks is likewise weighed. This tube is then heated to 
redness in a long tube-furnace, and connected at one end 
with the empty flask, at the other with a series of tubes filled 
with caustic potash and sulphuric acid, for the purpose of 
completely freeing the air passing through them from carbonic 
acid and aqueous vapor ; the cocks are then slightly opened 
and air allowed to pass slowly through the purifiers into the 
hot tube, where it is completely deprived of oxygen by the hot 
metallic copper which is thereby oxidized ; the nitrogen 
passes on alone into the empty flask. After the experi- 
ment is concluded, the cooled tube is again weighed, and the Elementary Chemistry. 
47 
increase over the former weighing gives the quantity of oxy- 
gen, whilst the increase in weight of the globe gives the 
nitrogen. The mean of a large number of experiments thus 
made shows that 100 parts by weight of air contained 23 parts 
by weight of oxygen and 77 of nitrogen. 
In addition to the two above-mentioned gases, the air con- 
tains several other important constituents, especially carbonic 
acid gas, aqueous vapor, and ammonia gas. We have 
already noticed (page 11) the important part which the car- 
bonic acid gas of the air plays in the phenomena of vegetation, 
this gas being the source from which plants obtain the car- 
bon they need to form their tissues. The quantity of carbonic 
acid present in the air is very small compared with the quan- 
tities of oxygen and nitrogen, being only about 4 vols. to 
10,000 of air ; nevertheless the absolute quantity of this gas 
contained in the whole atmosphere is enormously large (viz. 
about 3,000 billion kilogs.) The quantity of carbonic acid 
contained in the air can be found by drawing a known volume 
of perfectly dry air (not less than 20 litres) through weighed 
tubes containing caustic potash ; the increase in weight of 
the tubes gives the weight of carbonic acid contained in the 
air drawn through. Fig. 15 shows the arrangement of the 
Fig. iS. 
apparatus ; on the left is the aspirator, which by means of the 
flow of a known volume of water from the top to the bottom 48 
Elementary Chemistry 
vessel causes the passage of an equal volume of air through 
the tubes ; the two tubes farthest from the aspirator contain 
pumice-stone steeped in sulphuric acid, and serve to dry the 
air completely before passing into the next tube and potash 
bulbs, in which the carbonic acid is absorbed by caustic 
potash : the tube nearest the aspirator also contains sulphuric 
acid and pumice to avoid a loss of moisture from the potash 
solution in the bulbs. The quantity of carbonic acid con- 
tained in the air in different localities and under different cir- 
cumstances varies considerably—from 2 to more than 10 in 
10,000 vols. of air. In houses and closed inhabited spaces, 
the quantity of carbonic acid present is often much larger, 
and the object of ventilation is to reduce the quantity of car- 
bonic acid to as low a point as possible. Other methods for the 
estimation of carbonic acid are described in the larger manuals. 
Aqueous vapor is contained in the air in quantities vary- 
ing in different localities and at different times, and depend- 
ing mainly upon the temperature of the air. Air at a given 
temperature cannot contain more than a certain quantity of 
moisture in solution, and when it has taken up this maximum 
quantity, it is said to be saturated with aqueous vapor. The 
higher the temperature of the air, the more water can it retain 
as vapor, and when air saturated with moisture is cooled, 
the water is deposited in the liquid form in very small glo- 
bules, forming a mist, fog, or cloud. This is the cause of the 
fall of rain, snow, and hail ; when warm aif heavily laden with 
moisture from the ocean passes into a higher and colder posi- 
tion, or meets with a current of air of lower temperature, it 
cannot any longer retain so much aqueous vapor, and a 
large quantity assumes the liquid form, falling as rain when 
the temperature is above the freezing point, or crystallizing as 
snow-flakes if the temperature be below that point. Hail is 
caused by the congelation of raindrops by passing through a 
stratum of air below the freezing point. The quantity of rain 
thus deposited is very large : I cubic metre of air saturated 
with moisture at 250 C. contains 22-5 grms. of water, and if 
the temperature of this air be reduced to o° C, it will then be Elementaiy Chemistry. 
49 
capable of retaining only 5-4 grms. of water vapor ; hence 
iyi grms. of water will be deposited as rain. The air in 
England is often saturated with moisture, whilst the driest air 
observed on the coast of the Red Sea during a simoom con- 
tained only one-fifteenth of the saturating quantity. Instru- 
ments for ascertaining the degree of moisture or humidity of 
the air are termed hygrometers. 
The deposition of dew is caused by the rapid cooling of the 
earth’s surface by radiation after sunset, and by the conse- 
quent cooling of the air near the ground below the tempera- 
ture at which it begins to deposit moisture. 
The amount of aqueous vapor contained in the air at any 
time can be determined by the apparatus used for the estima- 
tion of the carbonic acid, for the moisture must be removed 
from the air before the carbonic acid can be absorbed, and 
the increase in weight of the tubes filled with pumice-stone 
moistened with sulphuric acid gives the weight of aqueous 
vapor. In general the air contains from 50 to 70 per cent, 
of the quantity necessary to saturate it. If the quantity be 
not within these limits the air is either unpleasantly dry or 
moist. 
The next important constituent of the air is ammonia, 
which is a compound of nitrogen and hydrogen, and only 
exists in comparatively very minute quantities (about 1 part 
in 1,000.000 of air). Nevertheless it plays a very important 
part, as it is mainly from this ammonia that vegetables obtain 
the nitrogen which they need to form their seeds and fruit; 
for it appears that plants have not the power of assimilating 
the free nitrogen of the atmosphere. Other substances which 
occur in the atmosphere in very small quantities may be con- 
sidered as accidental impurities. Amongst them, volatile 
organic matter is the most important, as probably influencing 
to a great extent the healthiness of the special situation. We 
become aware of the existence of such organic putrescent 
substances when entering a crowded room from the fresh air ; 
and it is probable that the well-known unhealthiness of 
marshy and other districts is owing to the presence of some Elementary Chemistry. 
50 
organic impurity. At present, however, we possess but little 
certain knowledge on this subject. Ozone is also present in 
fresh air, but generally absent in the close air of towns and 
dwelling-rooms, owing to its decomposition by the organic 
matter, &c., in such air ; we do not know how it is formed in 
nature, unless it be by the discharge of atmospheric elec- 
tricity. 
LESSON VI. 
Compounds of Nitrogen with Oxygen. 
We are acquainted with five distinct chemical compounds of 
nitrogen with oxygen, viz. : 
1 Nitrous Oxide, containing 28 parts by weight of N to 16 of 0 
2 Nitric Oxide, “ 28 “ “ 32 — 
3 Nitric Tri-oxide, “ 28 “ “ 48 — 
4 Nitric Tetr-oxide, “ 28 “ “ 64 — 
5 Nitric Pent-oxide, “ 28 “ “ 80 — 
It will be seen that the oxygen contained in these com- 
pounds is in the proportion of the numbers 1, 2, 3, 4, 5, to 
one and the same quantity of nitrogen ; and here, for the first 
time, we meet with a striking example of the law of chemical 
combination in multiple proportion. Thus, while 28 parts by 
weight of nitrogen combined with 16 parts of oxygen form 
44 parts of nitrous oxide, we find that any other compounds 
of these two elements contain some simple multiple of 16 
parts by weight of oxygen (thus, either 2x16, 3 x 16, 4 x 16, 
or 5 x 16), and that no compounds exist containing any inter- 
mediate quantity of oxygen. 
This law of multiple proportions was first enunciated by 
Dalton, and is the expression of well-established experi- 
mental facts. Dalton endeavored to explain these facts by Elementary Chemistry. 
51 
his celebrated Atomic Theory. He asked himself, Why do 
the elements combine only in multiples of their several com- 
bining proportions ? and he answered the question by the 
following supposition. 
Matter is made up of small indivisible portions, which he 
called Atoms (d, privative, and ■rsfivu, I cut). These atoms do 
not all possess the same weights, but the relation between 
their weights is represented by that of the combining weights 
of the elements ; thus he supposed the atom of oxygen to be 
16 times as heavy as the atom of hydrogen, and the weights 
of the atoms of nitrogen and oxygen as 14 to 16. Dalton 
further assumed that chemical combination consists in the 
approximation of the individual atoms to one another; and, 
having made these assumptions, he was able to explain why 
compounds must contain their constituents in the combining 
proportions, or in multiples of them, and in no intermediate 
proportion. Let us take, for example, the compounds of ni- 
trogen and oxygen ; the lowest of these consists of one single 
atom of oxygen combined with 2 atoms of nitrogen, or with 
one double atom of nitrogen, as it contains 16 parts of oxygen 
to 28 of nitrogen; thus, > and we therefore 
write its formula, N20, and call it nitrous oxide. The next 
compound that can be formed must be produced by the 
addition of another atom of oxygen to this ; thus we get 
®®®®=Na0a’ 
or nitric oxide. The next must be 
formed by the attachment of another atom of oxygen, and 
thus we get 03, or nitric tri-oxide. 
The next possible compound “N2O4 
or nitric tetr-oxide ;* and the next 
* If nitric oxide and nitric tetr-oxide be considered to be represented respec- 
tively by the formula N; O2 and Ns 04 they will be exceptions to the law mentioned 
on page 27, respecting the density of compound gases or vapors, as instead of 
having their densities represented by the halves of their combining proportions, 
they will have them represented by the quarters of these numbers. Elementary Chemistry. 
52 
=N206, or nitric pent-oxide. We thus see that an atom 
being indivisible, no intermediate compounds can be formed. 
In considering this subject, we shall do well to remember 
that the law of multiple proportions being founded on experi- 
mental facts, stands as a fixed bulwark of the science, which 
must ever remain true ; whereas the Atomic Theory, by which 
we now explain this great law, may possibly in time give 
place to one more perfectly suited to the explanation of new 
facts. 
Nitrogen and oxygen do not readily combine together, but 
under certain circumstances they are found to do so ; thus, 
if a series of electric sparks are passed through a glass vessel 
filled with dry air, the presence of red colored vapors, pos- 
sessing a peculiar acrid smell, is soon noticed. These con- 
sist of nitric tri-, and tetr-oxides, formed by the union of the 
nitrogen and oxygen of the air. If an alkali, such as potash, 
be present in the air through which the sparks are passed, a 
new substance, called nitre, or potassium nitrate, is formed; 
and from this an important compound, called nitric acid, can 
be prepared. This substance is formed when flashes of 
lightning pass through the air, being carried down to the 
earth’s surface in the rain. Nitric acid may be considered 
as a compound of nitric pentoxide with water ; and as all the 
other nitrogen oxides can be prepared from it, we shall first 
consider its properties and mode of preparation. 
Nitric Acid, or Hydric Nitrate.—Symbol H.N03, Com- 
bining Weight 63. Nitre, or potassium nitrate, is generally 
formed by the gradual oxidation of nitrogenous animal mat- 
ter in presence of the alkali potash. Spring water, especially 
the surface well-water of towns, frequently contains nitrates 
in solution, owing to water passing through soil containing 
decomposing animal matters, which by oxidation yield ni- 
trates. For this reason, water containing nitrates is unfit for 
drinking purposes. Potassium Nitrate, KNOa (commonly 
called saltpetre) occurs as an incrustation on the soil in various 
localities, especially in India; and Sodium Nitrate, NaN03, 
or Chili saltpetre, is found in large beds on the coast of Chili Elementary Chemistry. 
53 
and Peru. Nitric acid, H N03, is the hydrogen salt, and 
hence is termed Hydric nitrate : it may be regarded as 
H 7 
water, b O, in which one atom of hydrogen is replaced by 
H ) 
the group N02, thus, | O ; it is obtained by heating nitre, 
KNOs, with sulphuric acid, or Dihydric sulphate, H2 SO* ; 
when nitric acid, H NOa, and hydric potassium sulphate, 
HK SO4, are formed. The decompositions here effected may 
serve as the type of a very large number of chemical changes 
classed as double decoinpositions. These may all be repre- 
sented as consisting in an exchange between two elements, 
or groups of elements ; thus in the case in question, one 
atom of the hydrogen in the sulphuric acid changes place 
with one atom or its equivalent of, potassium in the nitre. 
These double decompositions maybe represented in the form 
of an equation, in which one side signifies the arrangement 
and relative weights of the elements before combination, 
theother the arrangement and relative weights o' the 
same elements after the chemical change has taken place, 
thus— 
KNO3 + H2S04 = H NOs + HK S04* 
or, Nitre and Sulphuric Acid give Nitric Acid and Hydric Potassium Sulphate. 
The relative weights of the elements and compounds entering 
into the decomposition is easily ascertained when we remem- 
ber that each symbol expresses not merely the nature of the 
element, but also the relative weight with which it combines, 
and that the combining weight of a compound is the sum of 
the combining weights of its constituents. The numbers ex- 
pressed by the above equation are 
K N Ojt Hi S 04 = H N O3 + H K SO4 
39'i + 14 + 48 + 2 + 32 + 64 — 1 + 14 + 48 + 1 + 39'i + 32+64 
ioi'i + 98 =63 + 136-1 
* The sign + placed between two symbols signifies “ and ” or “ together with.” 54 
Elementary Chemistry. 
We may express these double decompositions perhaps 
more clearly by representing by a curved line the actual 
exchange of hydrogen for potassium, thus— 
SH S04 
N03 
or by a straight line, thus— 
H I H S04 
NOa I K 
This signifies that if we require 63 parts by weight of nitric 
acid we shall require to take exactly ioi-i parts of nitre and 
98 parts of sulphuric acid, and that we shall have 136-1 parts of 
hydric potassium sulphate formed. Knowing these numbers, 
H S04 
N03 
H I H S04 
Fig. 16. 
it is easy to calculate the proportions of ingredients needed 
to produce any given quantity of nitric acid. 
Nitric acid is prepared on a small scale by placing equal 
weights of nitre and sulphuric acid in a stoppered retort, which 
is gradually heated by a Bunsen’s burner, as in Fig. 16: Elementary Chemistry. 
55 
the nitric acid formed distils over, and may be collected in a 
flask cooled with water. On a large scale this substance is 
prepared in iron cylinders, into which the charges of nitre 
and acid are brought, the nitric acid being collected in large 
stoneware bottles. 
Nitric acid thus obtained is represented by the formula H 
NOs; it is a strongly fuming liquid, colorless when pure, 
but usually slightly yellow from the presence of lower oxides 
of nitrogen. Its specific gravity is 1-51 at 180; it does not 
possess a constant boiling point, as it gradually undergoes 
decomposition by boiling and becomes weaker: if mixed with 
water, and distilled under the ordinary atmospheric pressure, 
the residual acid is found at last to attain a fixed composition, 
boiling constantly at I20°5, containing 68 per cent, of H N03, 
and possessing a specific gravity of rqiq. When mixed with 
less water, a stronger acid than this comes over ; when mixed 
with more water, a weaker one distils over till this constant 
composition is attained. Nitric acid contains 76 per cent, of 
oxygen, with some of which it easily parts ; hence it acts as a 
strong oxidizing agent; this is seen when we bring a small 
quantity of copper or tin into this liquid diluted with a little 
water; red fumes are immediately given off, and the metals 
are oxidized ; for the same reason nitric acid bleaches indigo 
solution, oxidizing, and therefore destroying, the coloring 
matter: this reaction, and the formation of red fumes in 
presence of metallic copper, &c., serve as modes of detecting 
the presence of nitric acid. One of the most delicate tests 
for this acid consists in adding to the liquid to be tested an 
equal volume of strong sulphuric acid, well cooling the mixture, 
and then carefully pouring on to its surface a solution of 
ferrous sulphate, Fe S04: a black ring is produced where the 
two layers of liquid meet if any nitric acid be present. Nitric 
acid forms, with metallic oxides, by the process of double 
decomposition, a numerous family of salts called nitrates: 
these are nearly all soluble in water, and many of them are 
largely used in the arts for various purposes. They will be 
mentioned under the several metals. Elementary Chemistry. 
56 
Nitric Pentoxide, or Nitric Anhydride.—Symbol N2 05, or 
NO. I o. This oxide of nitrogen cannot be prepared directly 
from liquid nitric acid ; but if dry chlorine gas be passed 
over silver nitrate, silver chloride is formed, oxygen is given 
off, and a white crystalline substance produced, which on 
analysis is found to be nitric pentoxide. The decomposition 
is thus represented— 
2 Ag NOs + 2 Cl. = N205 + O + 2 Ag Cl. 
Nitric Pentoxide melts at + 30° and boils at + 450 ; it very 
easily undergoes decomposition, and unites with great energy 
with water, forming nitric acid N208 + H20 = 2 N03H : 
this may be represented as a double decomposition, in which 
one atom of hydrogen changes place with N02, thus :— 
o + SI °=nh°1 
The fact that the composition of nitric pentoxide is repre- 
sented by the formula N205, may be ascertained experiment- 
ally by determining the quantity of nitrogen contained in 100 
parts of nitric pentoxide, which is first converted into nitric 
acid by the aid of water as above, and then into lead nitrate 
by treatment with lead oxide, thus :— 
Pb, O + 2 N03H = Pb, 2 N03 + H20. 
We thus find the nitrogen to weigh 25'93 parts, and hence 
the oxygen 100-25-93, or 74-07 parts. We then wish to know 
what is the simplest relation in which the combining weights 
of nitrogen and oxygen are contained in this compound ; in 
other words, what is the ratio of the number of atoms of 
nitrogen present to the number of those of oxygen. This is 
ascertained by dividing the above numbers by the respective 
combining weights of these two elements ; thus— 
=1-852 and 4-63: 
14 3 l6 J 
hence the ratio of the number of atoms of nitrogen present to 
the number of atoms of oxygen, is that of the numbers 1-852 to 
4-6294, or that of 2 to 4-999. Hence we conclude that the Elementary Chemistry. 
57 
exact relation between the number of atoms of nitrogen and 
oxygen respectively is that of 2 to 5, the slight difference 
which is noticed being due to the unavoidable errors which 
accompany every experimental inquiry, and are, therefore, 
termed errors of experiment. All the other oxides of nitrogen 
may be obtained from nitric acid by depriving it of its hydro- 
gen, and more or less of its oxygen. 
LESSON VII. 
Nitrous Oxide, or Laughing Gas.—Symbol N2 O, Combining 
Weight 44, Density 22, is obtained by heating ammonium 
.nitrate, NH4 N03 or 4 | O, in a flask such as that used 
for the production of oxygen, and is best collected over warm 
water (see Fig. 17), The salt decomposes on heating, into 
Fig. 17 
nitrous oxide and water; NH4 N03 = NgO + 2H2O ; or 
ammonium nitrate yields nitrous oxide and water. Nitrous 
oxide is a colorless inodorous gas possessing a slightly sweet 
taste; it is somewhat soluble in cold water, one volume of 
water at o° dissolving 1-305 volumes of the gas, whilst one 58 
Elementary Chemistry. 
volume of water at 24° dissolves only o-6o8 volume. Nitrous 
oxide differs from all the gases which we have previously 
considered, inasmuch as it liquifies when exposed either to 
great pressure or to an intense degree of cold. Thus, if it be 
brought under a pressure of about 30 atmospheres at o°, or if 
it be cooled down to - 88° under the ordinary pressure, it 
forms a colorless liquid (in other words the tension of nitrous 
oxide vapor or gas is 1 atmosphere at -88°, and 30 atmos- 
pheres at o° C). If this liquid be cooled below -115° it 
solidifies to a transparent mass. By the rapid evaporation 
of this liquid in vacuo, the lowest artificial temperature 
hitherto known has been attained, viz., about -140° C. 
A glowing chip of wood when plunged into nitrous oxide 
rekindles, and the wood continues to burn with a brighter 
flame than in the air, whilst phosphorus on burning in this 
gas evolves nearly as much light as in pure oxygen ; a feeble 
flame of sulphur is, however, extinguished on bringing it 
into this gas, but if burning strongly it also continues to burn 
brightly. This is owing to the fact that the gas has to be de- 
composed into nitrogen (1 volume) and oxygen (| a volume) 
before bodies can burn in it; and to effect this decomposition 
a tolerably high temperature is necessary,—the same products 
of combustion are produced as if the combustion went on in 
the air. When inhaled, nitrous oxide produces a peculiar in- 
toxicating effect on the human frame ; hence the name Laugh- 
ing gas. The composition of nitrous oxide may be determined 
Fig. 18. Elementary Chemistry. 
59 
as follows : a bent tube (Fig. 18) is filled with the dry gas over 
mercury up to a certain mark on the tube, a small pellet of 
metallic potassium having been previously introduced into the 
bent part of the tube; this is then heated by a spirit lamp, or 
Bunsen’s burner, while the open end of the tube is closed 
with the thumb under the mercury, to prevent a loss of gas 
by sudden expansion caused by the combustion. The potas- 
sium burns in the gas, uniting with the oxygen to form solid 
potassium oxide, or potash, whilst the nitrogen remains in the 
tube. On removing the thumb and allowing the tube to cool, 
it will be seen that the volume of nitrogen is exactly the same 
as the volume of nitrous oxide taken ; hence this gas contains 
its own volume of nitrogen. But we know by experiment 
that the weight of one volume of the gas is 22, so that if we 
subtract from this the weight of one volume of nitrogen (viz. 
14) we shall obtain the weight of oxygen (8) contained in one 
volume of nitrous oxide. Hence we see that two volumes of 
nitrous oxide are composed of two volumes of nitrogen and 
one volume of oxygen, or 44 parts by weight of nitrous oxide 
contain 28 of nitrogen and 16 of oxygen. The specific grav- 
ity of nitrous oxide (air= 1) is i'527 : 1000 cbc. at o° and 760 
mm. weigh i‘972 grm. 
Nitric Oxide.—Symbol NO; Combining Proportion 30; 
Density 15 ; a colorless gas obtained by acting upon copper 
turnings with nitric acid thus;—3 Cu. + 8 HNOs=3 (Cu. 
2 N03) + 2 NO+ 4 H20. Copper and nitric acid give copper 
nitrate, nitric oxide, and water. 
This substance has not been condensed to a liquid ; in con- 
tact with oxygen it combines directly with this latter gas, 
forming red fumes which are readily soluble in water, and by 
this property it may be distinguished from all other gases. 
Although nitric oxide contains half its volume of oxygen, and 
more oxygen in proportion by weight than nitrous oxide, it 
does not easily support combustion, as it requires a high tem- 
perature for its decomposition ; thus, ignited phosphorus, un- 
less burning very brightly, is extinguished on plunging it into 
nitric oxide gas. Elementary Chemistry. 
The composition of this gas may be determined according 
to the method described under nitrous oxide ; one volume of 
nitric oxide yields | a volume of nitrogen ; as the weight of 
one volume of nitric oxide is 15, the weight of oxygen con- 
tained in one volume of this gas is 15 — 7=8 : or two volumes 
of nitric oxide weigh 30, and are composed of one volume of 
nitrogen weighing 14, and one of oxygen weighing 16. Hence, 
in accordance with the law mentioned on p. 27 respecting the 
densities of compound gases, the formula of nitric oxide 
should be NO and not N202; the physical properties of the gas 
likewise, compared with those of nitrous oxide, seem to indi- 
cate that this latter has a more complicated constitution ; thus 
nitric oxide has not as yet been seen in the liquid form, does 
not condense to a liquid at temperatures and pressures at 
which nitrous oxide readily liquefies ; nitric oxide is more 
difficultly decomposed by heat than nitrous oxide, and there- 
fore supports combustion less easily ; and it is a general law 
that in a series of similar bodies the more complicated be the 
constitution of one member, the more readily does it con- 
dense to the liquid form, and the more easily does it decom- 
pose. 
The specific gravity of nitric oxide (air = 1) is 1-038, 
and 1,000 cbc of this gas at 0° and 760 mm. weigh 1-343 
grm- 
Nitric Trioxide, or Nitrous Anhydride.—Symbol N203; 
Combining Weight 76; Density 38. This substance is pre- 
pared by mixing four volumes of dry nitric oxide with one 
volume of oxygen, and cooling the mixture to — 18° ; the two 
gases combine to form red fumes, which condense to a vola- 
tile indigo-blue colored liquid ; the same blue body is ob- 
tained by adding water to nitric tetroxide and drying the distil- 
late over calcium chloride. When mixed with water nitric triox- 
ide decomposes, nitric oxide and nitric acid being formed, thus : 
3 Ns 03 + H2 O = 2 H N Os + 4 N O. 
As Nitric Pentoxide is connected with a series of salts 
called Ariirates, by the fact that all these salts may be re- Elementary Chemistry. 
61 
presented as nitric pentoxide, in which one of the groups 
N02 has been replaced by a metal, thus : 
Nitric pentoxide 2 | O ; potassium nitrate | O ; 
H 7 
hydric nitrate y O ; 
so also is nitric trioxide connected with a series of 
salts called Nitrites j thus : 
Nitric trioxide | O ; potassium nitrite |- O ; 
H 7 
hydric nitrite (unknown) r O. 
As Hydric Nitrate is known by the name nitrzV acid, so 
Hydric Nitrite is referred to as nxirous acid ; it being a gen- 
eral rule in chemical nomenclature that if the specific name of 
an acid or hydrogen salt end in “ ous,” the names of the cor- 
responding metallic salts end in “ite while if the name of 
the acid end in “ ic,” the names of the corresponding metallic 
salts end in “ ate thus nitric acid and potassium nitrate, 
nitrous acid and potassium nitrite, are respectively analogous. 
Potassium nitrite K NOs is obtained by heating nitre or 
potassium nitrate KNOs, when the third atom of oxygen is 
evolved ; and also by passing N203 into solutions of KHO. 
Nitric Tetroxide, or Nitric Peroxide.—Symbol N 02, Com- 
bining Weight 46, Density 23. This substance forms the 
greater part of the reddish brown fumes evolved when nitric 
oxide gas escapes into the air; it is however best prepared 
by heating lead nitrate in a hard glass retort; lead oxide, 
oxygen, and nitric tetroxide are produced by the decomposi- 
tion of the nitrate, thus ; 
2 (Pb 2 NOj) = 2 PbO + 4 N02 + 02. 
Nitric peroxide N02 solidifies at — 90 to long prisms ; 
these on fusing yield a yellow liquid, boiling at 220, Owing 
to the fact that the density of nitric tetroxide is 23, its formula 
is considered to be N02 and not N2 O*. 62 
Elementary Chemistry. 
Compounds of Nitrogen with Hydrogen. 
But one is as yet known in the free state, viz. : 
Ammonia.—Symbol N H3, Combining Weight 17, Density 
8-5. Nitrogen and hydrogen do not readily unite when 
brought together alone, but do so under certain circum- 
stances, especially when water is evaporated; the nitrogen 
of the air then combines with the elements of the water, 
forming small quantities of the compound ammonium nitrite 
q24 I Thus N2 + 2 H2 0=N2 H4 02, or NH4, N 02. 
Ammonia is chiefly obtained from the decomposition of animal 
or vegetable matter containing nitrogen and hydrogen, being 
formed either gradually at the ordinary temperature, or quickly 
under the influence of heat: thus when horns, or clippings of 
hides, or coal, is heated, ammonia is given off; hence ammo- 
nia was known as spirits of hartshorn. The name ammonia 
is derived from the fact that a compound containing ammonia, 
called salammoniac, was first prepared by the Arabs in the de- 
serts of Libya, near the temple of Jupiter Ammon, by heating 
camels’ dung. Guano, the dried excrement of sea birds, and 
the urine of animals, likewise contain large quantities of am- 
monia. Ammonia and its compounds are now, however, 
mainly obtained from the ammoniacal liquors of the gas- 
works : coal contains about 2 per cent, of nitrogen, which, 
when the coal is heated in close vessels, mostly comes off in 
combination with the hydrogen of the coal as ammonia. Am- 
monia may also be formed by the action of nascent hydrogen 
on dilute nitric acid ; thus, when this acid is placed in contact 
with metallic zinc or iron, ammonia is formed, thus : 
9HN03 + 4Zn=4(Zn2N03) + 3H20 + HsN. 
Ammonia gas is best prepared by heating in a glass flask 
one part of salammoniac, or ammonia hydrochlorate, NH3 H 
Cl or N H4C1, and two parts of powdered quicklime, thus 
CaO + 2 NH3 HC1 = CaCl2 + 2NH3 + H20. 
Quicklime and salammoniac give calcium chloride, and am- Elementary Chemistry. 
63 
monia and water. Ammoniacal gas is colorless, and pos- 
sesses a most pungent and peculiar smell, by means of which 
it can be readily recognized ; it is lighter than air, its specific 
gravity (air=i) being 0-59, and it may be collected by displace- 
ment, the neck of the bottle intended to receive the gas being 
turned downwards, as in Fig. 19. It may also be collected over 
mercury, but not over water, as it is extremely soluble in this 
liquid, one gramme of water at 0° absorbing 0-877 grms., or 
1149 times its volume of ammonia, under a pressure of 760 
mm. ; whilst at 20° the same weight of water absorbs 0-520 
grm., or 681'8 times its volume, under the same pressure. 
The solution of ammonia gas in water is the common Liquor 
Ammonias of the shops, which has a specific gravity of about 
o-88o. Ammonia gas, as well as the aqueous solution, pos- 
sesses a strong alkaline reaction, turning red vegetable colors 
blue: it unites with the most powerful acids, forming com- 
pounds called the Salts of Ammonia (see p. 167), wdiich closely 
resemble the salts of the alkaline metals ; hence the name of 
Fig. 19. 64 
Elementary Chemistry. 
the Volatile Alkali has been given to Ammonia. The action 
of ammonia gas on nitric acid may be thus represented : 
NH3 + N03H=N03NH4; or j O. 
Ammonia gas and nitric acid give ammonium nitrate. 
On exposure to a pressure of seven atmospheres at the or- 
dinary temperature of the air (about 15° C.), ammonia con- 
denses to a colorless liquid, boiling at — 3S-5° ; and this 
liquid, if cooled below — 750, freezes to a transparent solid ; it 
has at 0° the specific gravity 0-62. An elegant application of 
the principle of the latent heat of vapors has recently been 
made in the case of ammonia in M. Carry’s freezing machine, 
FIG. 20. 
Fig. 20. This consists essentially of two strong iron vessels 
connected in a perfectly air-tight manner by a bent pipe ; one 
of these vessels contains an aqueous solution of ammonia 
saturated with the gas at o°. When it is desired to procure 
ice, the vessel A containing the ammonia solution (which we 
will term the retort) is gradually heated over a large gas 
burner, the other vessel B (the receiver) being placed in a 
bucket of cold water : in consequence of the increase of tem- 
perature, the gas cannot remain dissolved in the water, and Elementary Chemistry. 
65 
passes into the receiver, where, as soon as the pressure 
amounts to about 10 atmospheres, it condenses in the liquid 
form. When the greater part of the gas has thus been driven 
out of the water, the apparatus is reversed, the retort (A) 
being cooled in a current of cold water, whilst the liquid it is 
desired to freeze is placed in the interior of the receiver 
(B). A re-absorption of the ammonia by the water now takes 
place, and a consequent evaporation of the liquefied ammonia 
in the receiver ; this evaporation is accompanied by an ab- 
sorption of heat, which becomes latent in the gas ; hence the 
receiver is soon cooled far below the freezing point, and ice is 
produced around it. 
The composition of ammonia may be ascertained by lead- 
ing the gas through a red-hot tube, or passing a series of elec- 
tric sparks through the gas, when it will be decomposed into 
nitrogen and hydrogen, which will be found to occupy together 
a volume twice as large as the ammonia taken, and to be mixed 
together in the proportions of three volumes of hydrogen to 
one volume of nitrogen. Hence the formula N H3 is given to 
the gas. 
The Salts of Ammonia will be described together with those 
of Potassium and Sodium (page 167). The compound ammo- 
nias will be noticed under Organic Chemistry. 
LESSON VIII. 
Carbon. Symbol C. Combining Weight 12. 
Carbon is the first solid element which we have to notice ; 
it is not known in the free state, either as a liquid or as a gas. 
Carbon is remarkable as existing in three distinct forms, 
which, in outward appearance or physical properties, have 
nothing in common, whilst their chemical relations are ident- 
ical. These three allotropic forms of carbon are (1) Diamond, 66 
Elementary Chemistry. 
(2) Graphite or Plumbago, (3) Charcoal: these substances 
differ in hardness, color, specific gravity, &c., but they each 
yield, on combustion in the air or oxygen, the same weight of 
the same substance, Carbonic Acid, or carbon di-oxide ;* 
12 parts by weight of each of these forms of carbon yielding 
44 parts by weight of carbon di-oxide. Carbon is the element 
which is specially characteristic of animal and vegetable life, 
as every organized structure, from the simplest to the most 
complicated, contains carbon : if carbon were not present on 
the earth, no single vegetable or animal body such as we now 
know could exist. In addition to the carbon which is found 
free in these three forms, and that contained combined with 
hydrogen and oxygen in the bodies of plants and animals, it 
exists combined with oxygen as free carbonic di-oxide in the 
air, and with calcium and oxygen as calcium carbonate in 
limestone, chalk, marble, corals, shells, &c. The fact has 
already been noticed that plants are able, when exposed to 
sunlight, to decompose the carbonic di-oxide of the air, liberat- 
ing the oxygen, and taking the carbon for the formation of 
their vegetable structure, whilst all animals living directly or 
indirectly upon vegetables absorb oxygen, and evolved car- 
bonic di-oxide. Thus the sun’s rays, through the medium of 
plants, effect deoxidation or reduction, while animals act as 
oxidizing agents with respect to carbon. 
The element carbon not only combines directly with oxy- 
gen, but also with hydrogen, forming a compound called Ace- 
tylene, C2H2. Carbon forms with oxygen, hydrogen, and 
nitrogen a series of more or less complicated compounds 
very much more extended than the series formed with these 
bodies by any other element; so that these compounds are 
considered as a separate branch of the science under the 
name of Organic Chemistry, or the Chemistry of the Carbon 
Compounds. The properties of the majority of these com- 
pounds will be examined in a subsequent chapter, owing 
* Although the term Acid strictly denotes a hydrogen salt, yet the word has been 
applied so long to a few other compounds containing no hydrogen, such as carbon 
di-oxide, &c., that these bodies are universally known by the names carbonic acid, &c. Elementary Chemistry. 
67 
to their complexity; hence till then it will be better to 
postpone the consideration of several of the properties of 
carbon. 
The Diamond was first found to consist of pure carbon by 
Lavoisier, in 1775-6, by burning it in oxygen, and collecting 
the carbon di-oxide formed; it occurs crystallized in certain 
sedimentary rocks and gravel in India (Golconda), Borneo, 
and the Brazils. Diamond occurs crystallized in forms (Fig. 
21), derived by a symmetrical geometric operation from a re- 
gular Octahedron, known as belonging to the regular system 
Fig. si. 
of Crystallography (see p. 150). The specific gravity of Dia- 
mond varies from 3-3 to 3-5 ; it is the hardest of all known 
bodies, and when cut possesses a brilliant lustre, and a high 
refractive power. In addition to its employment as a gem, 
the diamond is used for cutting and writing upon glass. We 
are altogether unacquainted with the mode in which the dia- 
mond has been formed ; it cannot, however, have been pro- 
duced at a high temperature, because when heated strongly 
in a medium incapable of acting chemically upon it, the dia- 
mond swells up, and is converted into a black mass resembling 
coke. 
Graphite, or Plumbago, crystallizes in six-sided plates 
which have no relation to the form in which the diamond crys- 
tallizes. Graphite occurs in the oldest sedimentary forma- 
tions, and in granitic or primitive rocks : it is found in Bor- 68 
Elementary Chemistry. 
rowdale in Cumberland, and in large quantities in Siberia and 
Ceylon, It has a black metallic appearance (whence the 
familiar name black lead), and leaves a mark when drawn 
upon paper. The specific gravity of graphite is 2-15 to 2-35. 
Coarse impure graphite may be purified by heating the powder 
with sulphuric acid and potassium chlorate; a compound is 
thus obtained which, on being heated strongly, decomposes, 
leaving pure graphite in a bulky and finely-divided powder: 
this powder when strongly compressed forms a coherent 
mass, from which pencils and other articles can be made. 
Graphite is used for polishing surfaces of iron-work, and also 
for giving a protecting varnish to grains of gunpowder. Gra- 
phite is produced in the manufacture of iron; it occa- 
sionally separates from the molten pig-iron in the form of 
scales. 
Charcoal is the third allotropic modification of carbon. It 
is obtained in a more or less pure state whenever animal or 
vegetable matter is heated to redness in a vessel nearly 
closed; the volatile matters (compounds of carbon, hydrogen, 
and oxygen) are thus driven off, and the residue of the carbon, 
together with the ash or mineral portion of the organism, re- 
mains behind. 
The purest form of charcoal carbon is found in lampblack ; 
it also occurs as wood charcoal, coal, coke, and animal char- 
coal. This form of carbon does not crystallize, and is hence 
termed amorphous ; it is much lighter than either of the other 
two forms, the specific gravity of powdered coke varying from 
I‘6 to 2*o. Charcoal appears at first sight to be lighter than 
water, as a piece of it floats on the surface of this liquid ; this 
is, however, due to the porous nature of the charcoal, for if it 
be finely powdered it sinks to the bottom of the water. This 
porous nature of charcoal enables it to exert a remarkable 
absorptive power, of which much use is made in the arts. 
Charcoal is thus able to absorb about ninety times its own 
volume of ammonia gas, and about nine volumes of oxygen. 
In the process of sugar-refining, use is made of the property 
of charcoal to absorb the coloring matters present in the raw Elementary Chemistry. 
69 
sugar: the kind of charcoal best suited to this purpose is that 
obtained by heating bones in a closed vessel. Charcoal is 
also used as a disinfectant in hospitals and dissecting rooms, 
&c. It appears that the putrefactive gases when absorbed by 
the charcoal undergo a gradual oxidation from contact with 
the oxygen of the air taken up by the charcoal, and are thus 
rendered harmless. 
Coal is a form of carbon less pure than wood charcoal. 
It consists of the remains of a vegetable world which once 
flourished on the earth’s surface : the original woody fibre has 
undergone a remarkable transformation in passing into coal, 
having been subjected to a process similar, in a chemical 
point of view, to that by which wood is transformed into 
Composition of Fuels (ash being deducted). 
Description of Fuel. 
Percentage Composition. 
Carbon. 
Hydrogen.! Nitro«en 
jand Oxygen. 
1 Woody Fibre 
2 Peat from the Shannon . 
3 Lignite from Cologne . . 
4 Earthy Coal from Dax 
5 Wigan Cannel .... 
6 Newcastle Hartley . . . 
7 Welsh Anthracite . . . 
52-65 
60‘02 
66-96 
74-20 
85-81 
88-42 
94-05 
5 25 
5-88 
5-25 
5-89 
585 
561 
3-38 
42-10 
34‘io 
27 76 
19-90 
8-34 
5'97 
2-57 
charcoal. It has not, however, lost the whole of its hydrogen 
and oxygen, and it has at the same time become bitumenized ; 
so that for the most part all the vegetable structure has dis- 
appeared. There are many different kinds of coal, containing 
more or less of the oxygen and hydrogen of the original wood : 
cannel coal and boghead coal contain the most hydrogen, and 
anthracite coal the least. The alteration in composition which 
wood has undergone in passing into the various forms of coal 
is seen from the above table. 70 
Elementary Chemistry. 
Cotnpounds of Carbon with Oxygen. 
Carbon forms two compounds with oxygen, viz.: 
Carbonic Oxide, or C O. 
Carbonic Dioxide, orCOj 
Carbonic Dioxide, or Carbonic Acid. Symbol C 03, Com- 
bining Weight 44, Density 22. 
Carbonic dioxide is always formed when carbon is burnt in 
excess of air or oxygen. It is best prepared by acting upon 
marble, chalk, or other form of calcium carbonate, with hydro- 
chloric acid. On pouring some of this acid upon pieces of 
marble contained together with some water in a flask, a rapid 
effervescence from the disengagement of carbonic dioxide gas 
at once occurs, calcium chloride being left behind in solution 
in the flask : the decomposition is thus represented : 
Ca C03 + 2HCI = C02 + H20 + Ca Cl3. 
Calcium carbonate and hydrochloric acid give carbonic 
dioxide, water, and calcium chloride. 
Carbonic dioxide occurs free in the air, and in the water of 
many mineral springs. The quantity of this gas present in 
the air is nearly constant, and amounts to about 4 volumes per 
10,000 of air; this quantity, though relatively small, is, taken 
altogether, very large, being about 3 billions of tons in weight, 
as can be easily calculated if we know the weight of the 
atmosphere and the density of carbonic acid. 
Owing to the evolution of carbonic dioxide in respiration 
and in the burning of coal-gas, &c., this gas is always found 
in larger quantities in dwelling-rooms than in the open air. 
When the air of a room contains o'io per cent, of this gas it 
is certainly unfit for continued respiration, not only on accoun 
of the deleterious effects produced by carbonic dioxide, but 
also because, together with this gas, volatile putrescible mat- 
ters are given off from the skin and lungs of animals, and these 
matters act in a prejudicial manner upon the health ; hence 
the necessity for attention to the ventilation of dwelling-rooms 
and public buildings. Carbonic dioxide gas is also given off Elementary Chemistry. 
71 
in the process of fermentation ; it occurs frequently at the 
bottom of old wells, and forms the chokedamp of the coal 
mines. Compounds containing calcium and magnesium, &c., 
and bearing a peculiar relation to carbonic dioxide, such as 
Ca) 
limestone or calcium carbonate, V 02, magnesian limestone, 
&c., occur plentifully in nature, sometimes forming whole 
mountain chains. Calcium carbonate also constitutes the 
main portion of coral, a substance of which whole continents 
are being built up in the Pacific Ocean. 
Carbonic dioxide gas is colorless and inodorous, but pos- 
sesses a slightly acid taste ; it is times heavier than air, 
and is tolerably soluble in water, one volume of water at o° 
dissolving 1797 volumes of this gas, whilst at 20° only o-goi 
volumes is absorbed. The volume of this gas absorbed by 
water at the same temperature is found to remain thfe same, 
whatever the density of the gas may be,—that is, howsoever 
the pressure may vary under which the gas is placed (the 
measurements of the volumes absorbed being made under 
these different pressures). As the volumes occupied by any 
given quantity of gas measured under different pressures vary 
inversely as these pressures, it is clear that the weights of gas 
thus absorbed must be proportional to the pressures. The 
same relation is found to hold good when many other gases 
are dissolved in water under varying pressures. 
The aqueous solution of carbonic dioxide reddens blue 
litmus paper, and when placed in contact with a metallic oxide, 
such as calcium oxide or lime, CaO, gives rise to the forma- 
tion of salts such as calcium carbonate : this aqueous solution 
may be considered to contain a true acid, the real carbonic 
H ) 
acid, >■ 02 (which, however, has never yet been isolated), 
and the reaction which then takes place may be thus repre- 
sented : 
| O. + Ca O = cCq |.02 + H20. 
Carbonic acid and calcium oxide give calcium carbonate Elementary Chemistry. 
7 2 
and water. The red color produced by the acid on litmus 
paper disappears on drying, owing to the decomposition of this 
true carbonic acid into carbonic dioxide and water, thus : 
| o2 = C02 + H.O. 
Carbonic dioxide can be condensed to a liquid by the appli- 
cation of great pressure, or by cooling the gas to a very low 
temperature: liquid carbonic dioxide is a colorless and very 
mobile liquid, which is remarkable as being found to expand 
by heat more than the gaseous form of the same substance, 
100 volumes of this liquid at o° becoming 106 volumes at io°, 
while 100 volumes of the gas at o° must be heated to i6-4° 
before they expand to 106 volumes ; hence this body is an 
exception to the rule that liquids expand by heat less than 
gases, and at the same time forming an excellent illustration 
of the* fact, that liquids expand proportionally much more 
when submitted to a high pressure than when under a 
low one ; thus, the expansion of water above ioo° is much 
greater than that below ioo°. The boiling point of carbonic 
dioxide is -78°. At a still lower temperature it freezes to a 
colorless, ice-like solid. At 0° the tension of its vapor is 
35-5 atmospheres ; and, at 30°, 73-5 atmospheres. The lique- 
faction of carbonic dioxide gas can be effected either by evolv- 
ing the gas in a strong closed vessel, so that it is condensed 
by its own pressure, or by pumping the gas by means of an 
ordinary forcing syringe into a strong wrought-iron receiver, 
kept during the process at a temperature of o°. As soon as 
the volume of gas pumped in amounts to about 36 times the 
volume of the receiver, each stroke of the syringe produces a 
condensation of the gas which is pumped in, and thus the 
receiver can easily be filled with liquid. If the stopcock be 
then opened so that the liquid is forced out, a portion at once 
assumes the gaseous state ; and so much heat is absorbed by 
this sudden transition from the liquid to the gaseous form, that 
a portion of the liquid is solidified and deposited in the form 
of white, snow-like flakes, which can be collected by allowing 
the stream of liquid to flow into a thin brass box, with per- Elementary Chemistry. 
73 
forated sides. Solid carbonic dioxide thus obtained, is a light, 
snow-like substance, which, owing to the bad conducting 
power for heat of the gas which the solid substance is con- 
stantly giving off, may be handled without damage, although 
its temperature is below -78° C. If, 
however, the solid be forcibly pressed 
between the fingers, so that the sub- 
stance really comes in contact with 
the skin, a sharp pain will be felt, and 
a blister like one produced by touch- 
ing a hot iron will be produced. This 
solid carbonic dioxide is much used 
for the production of very low tem- 
peratures ; for this purpose it is 
mixed with ether, and the mixture 
brought into the vacuum of the air- 
pump, whereby a temperature as low 
as -ioo° C. can be obtained, and 
large quantities of mercury may eas- 
ily be frozen. Carbonic dioxide gas 
does not support the combustion of 
bodies in general, such as wood, 
sulphur or phosphorus ; but certain 
metals—for instance, potassium and 
magnesium—heated in the gas, are 
able to decompose it, burning in it, 
and uniting with the oxygen to form 
oxides, while the carbon is liberated. 
Fig. 22. 
The composition of carbonic diox- 
ide may be ascertained with great ex- 
actness by burning a known weight of 
pure carbon, such as the diamond, in 
a current of pure oxygen gas, and 
weighing the carbonic dioxide pro- 
duced. The apparatus for this synthesis of this gas is repre- 
sented in Fig. 22. The weighed quantity of diamond placed in 
a small platinum boat, is pushed into the porcelain tube, which 74 
Elementary Chemistry. 
can be strongly heated in the furnace. One end of this tube 
is connected with a gasholder and drying tubes, A, B, C, by 
means of which pure and dry oxygen gas is supplied. The 
other end is connected, as is seen, with a number of tubes 
and bulbs destined to absorb the carbonic dioxide formed 
by the combustion ; the tube D and the bulbs E contain 
solution of caustic potash, and the other tubes F are filled 
with pumice-stone and sulphuric acid. The bulbs and tubes 
are carefully weighed, and then the apparatus is filled with 
pure oxygen, and the tube slowly brought to a red heat. 
The gas passes gradually through the system of tubes, and 
carries along with it the carbonic dioxide formed by the 
combustion of the diamond: this gas is wholly absorbed 
by the potash in the tube and bulbs, whilst any moisture 
which might be given off from the bulbs is taken up by 
the tubes F. The oxygen gas is dried as it enters and also 
as it leaves the apparatus ; so that the gain in weight which 
the tubes have experienced gives exactly the weight of car- 
bonic dioxide formed by the combustion of the carbon of the 
diamond. Usually the diamond contains a small quantity of 
ash, or inorganic matter, and this weight must be subtracted 
from the original weight of the diamond, in order that we may 
know the exact weight of pure carbon burnt ; for this reason 
the diamond is placed in a platinum boat, which can be with- 
drawn and weighed after the experiment, and thus the amount 
of ash determined. Another precaution that must be taken 
is, to fill the greater part of the red-hot tube with porous cop- 
per oxide, in case any trace of carbonic oxide gas (C O) should 
be formed by the incomplete combustion of the carbon ; this 
gas would pass unabsorbed through the potash if not oxidized 
to carbonic dioxide by the copper oxide. In this way it has 
been shown that 100 parts of carbonic dioxide consist of 
Carbon 27^27 
Oxygen 7273 
Carbonic dioxide . . 100 00 Elementary Chemistiy. 
75 
If we divide 27-27 by the combining weight of carbon, and 
27-27 7273 
72-73 by that of oxygen, we have ■■ — 2-273 and — 
4-545 ; or, the relation between the number of atoms of car- 
bon and that of those of oxygen is that of 1 to 2 ; hence the 
formula of carbonic dioxide is C 02. Hence the gas should 
contain its own volume of oxygen ; for 44 parts by weight of 
carbonic dioxide occupying a volume equal to that occupied 
by 2 parts by weight of hydrogen, contain 32 parts by weight 
of oxygen, which likewise occupy a volume equal to that of 2 
parts of hydrogen. That this is the case can be experiment- 
ally proved by burning charcoal in a known volume of oxygen 
in excess, when it is observed that when the gas has cooled 
after the combustion, no alteration in its volume has occurred ; 
hence the volume of carbonic dioxide formed must be precisely 
equal to that of the oxygen used in its formation. 
LESSON IX. 
Carbonic Oxide. Symbol CO. Combining Weight 28. 
Density 14. 
When carbon burns with a limited supply of oxygen, car- 
bonic oxide is formed. The production of this gas in an 
ordinary red-hot coal fire is often observed ; oxygen of the 
air, which enters at the bottom of the grate, combines with 
the carbon of the coal, forming carbonic dioxide ; this sub- 
stance then passing upwards over the red-hot coals, parts 
with half its oxygen to the red-hot carbon ; thus :— 
COa + C = 2 CO. 
This carbonic oxide on coming out at the top of the fire 
meets with atmospheric oxygen, with which it at once com- 
bines, burning with a lambent blue flame, and reforming car- Elementary Chemistry. 
bonic dioxide. Carbonic oxide gas in the pure state can be 
prepared by passing a slow current of carbonic oxide over 
pieces of charcoal heated to redness in a tube by means of a 
furnace, as represented in Fig. 23 : it may likewise be ob- 
tained in the pure state from several compounds of carbon. 
Thus, if crystallized oxalic acid be heated with strong sul- 
phuric acid, a mixture of equal volumes of carbonic oxide and 
carbonic dioxide gases is evolved ; this latter can be easily 
separated from the former by shaking the mixed gas up with 
caustic soda solution, when sodium carbonate will be formed, 
Fig. 23. 
half the volume of the gas will disappear, and the remainder 
will be found to be pure carbonic oxide. This decomposition 
of oxalic acid results from the fact that sulphuric acid has a 
strong tendency to abstract water, or the elements of water, 
from the bodies with which it comes into contact; thus the 
oxalic acid, which may be represented as Ca H2 04 {see p. 
289), being deprived of the elements of one molecule of water, 
which are taken up by the sulphuric acid, yields a compound, 
C2 03, which cannot exist alone, and immediately splits up 
into CO2 and CO. 
Carbonic oxide can also be prepared by heating Formic 
acid, C H2 Oa {see p. 271), with sulphuric acid : here, as with 
oxalic acid, the elements of water are removed, and pure CO Elementary Chemistry. 
77 
is thus evolved. Carbonic oxide is a colorless, tasteless gas, 
which has not been condensed to a liquid ; it is a little lighter 
than air, its specific gravity being 0-969 (air =1 ) ; it is but 
very slightly soluble in water. It acts as a strong poison, 
producing death when inhaled even in very small quantities, 
the fatal effects often observed of the fumes from burning 
charcoal, or from limekilns, being due to the presence of car- 
bonic oxide. When heated in contact with oxygen, carbonic 
oxide takes fire, burning with a characteristic lambent blue 
flame and forming carbonic dioxide. In contact with caustic 
potash at a high temperature, carbonic oxide produces potas- 
sium formate thus: 
+ CO = CHK02. 
Caustic potash and carbonic oxide give potassium formate. 
The composition of this gas can be ascertained by combus- 
tion in the Eudiometer with oxygen. 100 volumes of car- 
bonic oxide and 75 volumes of oxygen yield on passing the 
electric spark 125 volumes, of which 100 are found to be 
absorbed by caustic potash, and hence are carbonic dioxide, 
the remaining 25 volumes being unaltered oxygen. Hence 
the volume of carbonic dioxide produced is equal to that of 
the carbonic oxide taken, whilst the volume of oxygen needed 
is half as large. But as carbonic dioxide contains its own 
volume of oxygen, carbonic oxide must contain half its volume 
of oxygen ; or two volumes of this gas weighing 28 contain 
one volume of oxygen weighing 16, and hence 12 parts of 
carbon by weight: therefore its formula is CO. 
Compounds of Carbon with Hydrogen. 
These compounds are very numerous ; they are known in 
the gaseous, liquid, and solid forms. The most important and 
numerous parts of these will be considered under Organic 
Chemistry ; we have only now to speak of two, viz : 
Light carburettedhydrogen, CH4 
Heavy carburetted hydrogen, C2H4. 78 
Elementary Chemistry. 
Methyl Hydride, Light Carburetted Hydrogen, or Marsh 
gas. Symbol CH4 ; Combining Weight 16, Density 8. 
This is a colorless, tasteless, inodorous gas, which has 
not been condensed to a liquid. It is found in coal mines, 
and known under the name of firedamp; it also occurs in 
stagnant pools, being produced by the decomposition of dead 
leaves, whence the name marsh gas ; it is one of the con- 
stituents of coal gas, &c., and’ is evolved in many volcanic 
districts. Marsh gas may also be artificially prepared by heat- 
ing sodium acetate (see p. 275) with caustic soda, thus : 
Na |o . H In- Na’io 4- H 
C2H30 } U +Na|U~ CO \ °2 + CH3. 
Sodium acetate and caustic soda give sodium carbonate 
and marsh gas. 
Marsh gas burns with a bluish-yellow non-luminous flame, 
forming carbonic dioxide and water ; with a limited supply of 
air it yields several products, amongst which is acetylene, 
C2H2. If mixed with ten times its volume of air, and twice 
its volume of oxygen, it ignites with a sudden and violent 
explosion on the application of a light, and hence the great 
damage produced by the escape of this gas in coal mines. 
The composition of marsh gas is ascertained by exploding it 
with oxygen in the eudiometer ; 1 volume of this gas and 3 
volumes of oxygen yield 2 volumes after passage of the spark. 
On absorbing by potash the carbonic dioxide produced, 1 
volume of oxygen is found to remain. Hence of the 2 volumes 
of oxygen needed to burn the 1 volume of marsh gas, 1 has 
gone to unite with the carbon, and 1 to form water with the 
hydrogen. It is thus seen that 2 volumes of marsh gas con- 
tain 4 volumes of hydrogen weighing 4 (as water contains 2 
volumes of hydrogen and 1 of oxygen), and as much carbon 
as is contained in 2 volumes of carbonic dioxide, viz., 12 
parts by weight: and hence the formula CH4 is given to this 
gas. 
Ethylene, Heavy Carburetted Hydrogen or Olefia7tt Gas. 
Symbol C2 H4, Combining Weight 28, Density 14. 
This gas is obtained on the destructive distillation of coal, Elementary Chemistry. 
79 
and is an important constituent of coal gas. It is obtained in 
the pure state by heating i part of alcohol (spirits of wine) 
C2 He O, with 5 or 6 parts by weight of strong sulphuric acid ; 
as in formation of carbonic oxide from formic acid, the ele- 
ments of water are separated by the sulphuric acid, and C2H« 
is evolved as a gas. This gas is colorless, but possesses a 
sweetish taste ; by exposure to a high pressure at a tempera- 
ture of—i io° it has been condensed to a colorless liquid. 
On bringing it in contact with a light, in the air, it burns with 
a luminous smoky flame, forming carbonic dioxide and water. 
When mixed with three times its bulk of oxygen and fired, it 
detonates very powerfully ; I volume of olefiant gas requires 
3 volumes of oxygen to burn it completely, and yields 2 
volumes of carbonic dioxide ; so that I volume of oxygen is 
needed to combine with the hydrogen. Hence this gas con- 
tains twice as much carbon as marsh gas, with the same 
quantity of hydrogen ; we must therefore write its formula 
C2 H-i. 
Olefiant gas combines directly with its own volume of 
chlorine gas, forming an oily liquid, and owing to this prop- 
erty it has received the above name. 
Coal Gas. 
The gas so largely used for illuminating purposes, and ob- 
tained by the destructive distillation of coal (z. e. by heating 
the coal in large closed retorts so as to decompose or destroy 
the coal, the volatile products of this decomposition being 
condensed and collected), is not a simple chemical compound, 
but a mixture of a large number of distinct substances. In 
order to prepare coal gas of good quality, cannel, or some 
highly bitumenized coal is heated in a closed retort; volatile 
bodies are thus formed and expelled, while a residue of (im- 
pure) carbon is left behind as coke. The volatile products of 
this decomposition may be distinguished as tar, ammonia, 
water, and gas. The tar contains a great variety of sub- Elementary Chemistry. 
stances, from some of which the well-known Aniline colors 
are produced (see p. 322); and the ammonia derived from the 
nitrogen in the coal is our chief source of ammoniacal salts 
(see p. 174). The gas which comes off consists of a mixture 
of various substances, some of which are useful for illuminat- 
ing or heating purposes, whilst some are hurtful and must be 
removed. Amongst those which burn with a luminous flame, 
are olefiant gas, and other hydrocarbons having an analogous 
composition, as C3 H6 and C4 H8 (where the number of atoms 
of hydrogen is double that of those of carbon). The gases 
which serve to dilute these luminous hydrocarbons, and burn 
themselves with non-luminous flames, are hydrogen, carbonic, 
oxide, and marsh gas. The impurities consist of carbonic 
dioxide, hydric sulphide (sulphuretted hydrogen), and the va- 
por of carbon di-sulphide ; and these substances are almost 
always withdrawn from the gas by a system of purification be- 
fore it is sent out from the gasworks. The relative propor- 
tion of these three ingredients present in coal gas varies 
greatly according to the kind of coal employed, and according 
to the heat to which the coal is subjected. This is seen from 
the following table, in which the composition of a gas made 
from common coal with that of one made from cannel is 
given : 
Illumi- 
nating 
Composition in ioo volumes. 
power: 
in 
Candles 
per s 
cubic 
feet. 
Hydro- 
gen. 
Marsh 
Gas. 
Heavy 
Hydro- 
carbons. 
Equal to 
Olefiant 
Gas. 
Carbonic 
Oxide. 
Nitrogen, 
Oxygen, 
and 
Carbonic 
Acid. 
Cannel Gas. 
34’4 
25-82 
51*20 
13-06 
(22-08) 
7'8S 
2 .07 
Coal Gas.... 
i3’° 
47-60 
4i'S3 
3-os 
( fi‘97) 
7-82 
— 
The value of coal gas, as regards its illuminating power, is 
ascertained by comparing the light given off by the gas burn- 
ing at a certain rate, usually 5 cubic feet per hour, with that Elementary Chemistry. 
81 
of a sperm candle burning 120 grains per hour. Thus the 
cannel gas is said to be equal to 34-4 candles, and the coal 
gas to be equal to 13 candles. 
It will be convenient here to mention the nature and struc- 
ture of flame, and the principle of the Davy lamp. Flame 
consists of gas in a high state of ignition. When a jet of 
burning hydrogen is plunged into oxygen, the flame of hydro- 
gen in oxygen is seen. This is caused by the ignition of the 
particles of hydrogen and oxygen, owing to the heat evolved 
in their combination. A similar flame of oxygefi in hydrogen 
is seen when a jet of the former gas is lit in an atmosphere of 
hydrogen. The temperatures of flames differ as much as 
their illuminating powers, and the hottest flames do not neces- 
sarily give off much light; thus the oxyhydrogen flame, which 
is so hot as to burn iron or steel wire like tinder, can scarcely 
be seen in bright daylight. In order that a flame shall give 
off much light, it must contain solid matter, which becomes 
heated up to whiteness. If a piece of 
lime be held in the oxyhydrogen flame, 
it becomes strongly heated, and gives 
off an intense light; so also if we bring 
solid matter, such as powdered charcoal, 
into the colorless flame of hydrogen, it 
becomes luminous. The difference be- 
tween the non-luminous flame of marsh 
gas and the luminous flame of olefiant 
gas is due to the fact that in the latter, 
carbon is separated out in the solid form, 
whereas in the former all the carbon is 
at once burnt to a carbonic acid. The 
flame of a candle consists of three dis- 
tinct parts—(1), the dark central zone or 
supply of unburnt gas surrounding the 
wick; (2), the luminous zone or area of incomplete combus- 
tion ; and (3), the non-luminous zone or area of complete com- 
bustion. If we bring one end of a small piece of glass tubing 
(Fig. 24) into the dark central zone (1), the unburnt gases will 
Fig. 24. 82 
Elementary Chemistry. 
pass up the tube, and may be ignited at the other end, where 
they escape into the air. In the luminous part of the flame 
the gases are not completely burnt, and carbon is separated 
out in the solid state ; and it is to the presence of this car- 
bon that the flame owes its luminous power. In the outer 
zone the supply of oxygen is greater, all the carbon is at once 
burnt to carbonic acid, and the flame here becomes non- 
luminous.* 
The effect of allowing a complete combustion to proceed at 
once throughout the flame is well seen in the small Bunsen 
gas-lamp, now universally employed in laboratories. In this 
lamp (Fig. 25) the coal gas issues from a small central burner 
(a), and passing unburnt up the tube {e) draws air up with it 
through the holes (d); the mixture of air and gas thus made 
can be lighted at the top of the tube, where it burns with a 
Fig. 25. 
Fig. 26. 
non-luminous, perfectly smokeless flame ; if the holes (d) be 
closed, the gas alone burns with the ordinary bright smoky 
flame. The blow-pipe flame (Fig. 26) may also be divided 
into two distinct parts—the oxidizing flame (a), where there 
is excess of oxygen, and the reducing flame, (b) where there 
is excess of carbon ; and these are distinguished by the same 
* The optical difference between these two classes of flame is pointed out in the 
paragraph on Spectrum Analysis, (see p. 222.) Elementary Chemistry. 
83 
properties as the outer and inner mantle of the candle flame. 
Every mixture of gases requires a certain temperature to in- 
flame it; and if the temperature be not reached, the mixture 
does not take fire ; we may thus cool down a flame so much 
that it goes out, by placing over it a small coil of cold copper 
wire, whereas, if the coil be previously heated, the flame will 
continue to burn. The same fact is well shown with a piece 
of wire gauze containing about 700 meshes to the square inch : 
if this be held close over a jet of gas, and the gas lit, it is pos- 
sible to remove the gauze several inches above the jet, and 
yet the inflammable gas below does not take fire, the flame 
burning only above the gauze (Fig. 27). The metallic wires 
in this case so quickly conduct away the heat that the tem- 
perature of the gas at the lower side of the gauze cannot rise to 
the point of ignition. This simple principle was made use of by 
Sir Humphry Davy in his safety-lamp for coal mines. It con- 
sists of an oil lamp (Fig. 28), the top of which is inclosed in a 
Fig. 27. 
Fig. 28. 
covering of wire gauze ; the air can enter through the meshes 
of the gauze, and the products of combustion of the oil can es- 
cape, but no flame can pass from the inside to the outside of 
the gauze ; and hence, even if the lamp be placed in a most in- 
flammable mixture of fire-damp and air, no ignition is possi- 84 
Elementary Chemistry. 
ble, although the combustible gas may take fire and burn in- 
side the gauze. It is, however, then advisable that the miner 
should withdraw, to avoid risk of explosion of the gas from 
the gauze thus becoming overheated and inflaming the fire- 
damp which surrounds it. The compounds of carbon being 
generally of a more complicated nature than the preceding 
ones, they will be more completely considered under the head 
of Organic Chemistry. 
Compounds of Carbo7i and Nitrogen. 
Oriq only is known, viz.; 
Cyanogen. Symbol CN. Combining Weight 26. Den- 
sity 26. 
When carbon and nitrogen are heated together in presence 
of potash, a remarkable compound, termed Potassium Cyanide, 
KCN, is formed. From this substance a large number of 
bodies can be prepared, all of which contain the group of 
atoms CN, and possess characteristic and peculiar properties ; 
to this group the name Cyanogen is given, from its forming a 
number of blue compounds (xvaw)? blue, and yswato, I produce). 
Cyanogen combines with metals to form Cyanides, and in this 
respect resembles chlorine. 
CN ) * 
Gaseous Cyanoge7i > can be easily obtained as a 
colorless gas by heating mercuric cyanide. It is best col- 
lected over mercury, as it is soluble in water. It condenses 
to a colorless liquid when exposed to a pressure of about 
four atmospheres ; it is inflammable, and burns with a beauti- 
ful purple flame, forming carbonic acid (dioxide C02) and free 
nitrogen. Cyanogen compounds are prepared on a large 
scale for various purposes by heating nitrogenous organic 
matter, such as clippings of hides, hoofs, &c.; with iron and 
potashes, a double cyanide containing iron and potassium, 
* The reason for giving the double formula to gaseous cyanogen will be explained 
further on. Elementary Chemistry. 
85 
called Potassium Ferrocyanide, or yellow Prussiate of Potash 
(see Organic Chemistry, p. 298), is formed. 
Cyanogen forms with hydrogen a compound analogous in 
composition to hydrochloric acid HC1, and called Hydrocyanic 
Acid., or commonly, Prussic Acid., HCN. This important 
substance is prepared by acting on potassium cyanide with 
dilute sulphuric acid in a retort. Hydrocyanic acid mixed 
with water distils over, leaving potassium sulphate in the 
retort, thus: 
2 K CN + H2 S04 = Ka SO4 + 2 HCN. 
It is prepared pure and free from water by passing sul- 
phuretted hydrogen gas, H2 S, over dry mercuric cyanide, 
hydrocyanic acid, and mercurous sulphide being formed, 
thus : 
2 Hg CN + H2S = 2 (HCN) + Hg2S. 
Mercuric cyanide and sulphuretted hydrogen yield hydro- 
cyanic acid and mercurous sulphide. Hydrocyanic acid thus 
prepared is a volatile liquid, boiling at 26-5°, and solidifying 
at—150 ; it is the most poisonous substance known, one 
drop of the pure substance being sufficient to produce fatal 
results ; much care must therefore be taken in its preparation 
not to inhale the vapor which, even in small quantity, may 
produce death. It possesses a peculiar and characteristic 
smell of bitter almonds, and occurs in small quantities in the 
kernels and leaves of many plants. 
Cyanogen forms a large number of compounds, some of 
them of a very complicated constitution, and connected with 
other carbon compounds, under which they will be considered. 
LESSON X 
We now pass to the consideration of a group of elements 
which resemble each other closely, and possess strongly- 86 
Elementary Chemistry. 
marked and active properties : viz. Chlorine, Bromine, Iodine, 
and Fluorine. 
Chlorine. Symbol Cl. Combining Weight 35-5- 
Density 35’5. 
Chlorine was discovered in the year 1774 by Scheele : it 
does not occur free in nature, but can easily be prepared 
from its compounds. It is found combined with metals form- 
ing chlorides ; of these sodium chloride, sea or rock-salt, is 
the most common: to obtain chlorine from this, it must be 
heated with sulphuric acid and manganese dioxide, thus : 
2 NaCl + 2 SO4 H2 + MnOs = 2 Cl + Na2 S04 + MnS04 
4- 2H20. 
Sodium chloride, sulphuric acid, and manganese dioxide, 
give chlorine, sodium sulphate, manganese sulphate, and 
water. 
If one part of salt to one part of manganese dioxide be 
mixed with two parts of sulphuric acid and two of water, and 
the mixture brought into a large flask, the chlorine gas is 
given off regularly upon the application of a very slight heat; 
in order to obtain the gas pure, it may be passed through the 
water contained in a wash-bottle before it is collected for use. 
Chlorine is a green-yellow gas, possessing a most disagreeable 
and peculiar smell, which, when the gas is present in small 
traces only, resembles that of seaweed, but when present in 
large quantities acts as a violent irritant, producing inflamma- 
tion of the mucous membrane, and even causing death when 
inhaled. Chlorine gas when submitted to a pressure of five 
atmospheres at the ordinary temperature, is condensed to a 
heavy yellow liquid, but it has not yet been solidified. This 
gas cannot be collected over water or mercury, as it is soluble 
in the former (1 volume of water dissolving 2'37 volumes of 
chlorine at 150), and combines directly with the latter, forming 
mercuric chloride. It can, however, be easily collected by 
displacement, as it is nearly 2'5 times as heavy as air. If Elementary Chemistry. 
87 
metals in a freely divided state are brought into chlorine gas, 
they take fire spontaneously, forming metallic chlorides: 
thus powdered arsenic, antimony, or thin copper leaf, burn 
when thrown into the gas. 
The most remarkable property of chlorine is its power of 
combining with hydrogen to form hydrochloric acid : when 
these two gases are brought together in equal volumes, they 
combine with explosion on bringing a flame into contact with 
them, or on exposing the mixture to sunlight. Chlorine is 
even able to decompose water in the sunlight, combining with 
the hydrogen and liberating the oxygen. Several experiments 
illustrative of this property of chlorine may be mentioned : if 
a burning candle be plunged into this gas, the taper continues 
to burn, but with a very smoky flame, the hydrogen alone of 
the wax entering into combination with the chlorine, whilst 
the carbon is given off as smoke or soot: the same effect is 
produced when a paper moistened with turpentine (a com- 
pound of carbon and hydrogen) is held in a jar of chlorine 
gas ; the hydrogen of the turpentine at once combines with 
the chlorine, forming hydrochloric acid, and the carbon is 
liberated ; so much heat is given off by this action that the 
paper frequently takes fire. 
The well-known bleaching action of chlorine also depends 
upon its power of combining with the hydrogen of water and 
liberating the oxygen. Dry chlorine gas does not bleach ; 
we may inclose a piece of cotton cloth or paper colored by a 
vegetable substance, as madder or litmus, in a bottle of dry 
chlorine, and no change of color takes place, even after the 
lapse of many weeks : if, however, a few drops of water are 
added, the coloring matter is immediately destroyed, and the 
cotton or paper is bleached. Here the chlorine combines with 
the hydrogen of the water, and the oxygen at the moment of 
its liberation (when it is said to be nascent) combines with the 
vegetable coloring matters, forming compounds destitute of 
color. Ordinary free oxygen has not this power—not at least 
to any great extent; it is a frequent observation that bodies 
in this nascent state have more active properties than the 88 
Elementary Chemistry. 
same bodies when free and alone. Chlorine is unable to 
bleach mineral colors ; the difference between printer’s ink, 
colored by lampblack or carbon, and writing ink, a vegetable 
black, is wrell illustrated by placing a sheet of paper having 
characters written and printed upon it in a solution of chlorine 
in water. Chlorine gas is largely used for bleaching purposes 
in the cotton, linen, and paper manufactures. It is sometimes 
used in the form of a gas, but more usually in combination 
with calcium and oxygen, forming the article called chloride 
of lime (mixture of calcium chloride, CaCl2, and calcium hypo- 
chlorite, CaCI202) or Bleaching Powder. Chlorine is also 
largely employed as a disinfectant and deodorant, its action 
on organic putrefactive substances being similar to that upon 
organic coloring matters. 
Compounds of Chlorine with Hydrogen. 
One only is known, viz :— 
Hydrochloric Acid, or Hydric Chloride. Symbol HC1. 
Combining Weight 36'5. Density 18.25. 
This substance is obtained when equal volumes of chlorine 
and hydrogen are mixed and exposed to the diffused light of 
day ; the gases then combine, and form an unaltered volume 
of hydrochloric acid gas. If the light be strong, this combi- 
nation takes place so rapidly that a violent explosion occurs. 
Hydrochloric Acid may, however, be more easily prepared by 
heating common salt (sodium chloride) and sulphuric acid in 
a flask. 
NaCl + S04 H2 = HC1 + Na H So4. 
Sodium chloride and sulphuric acid give hydrochloric acid 
and hydric sodium sulphate. 
Hydrochloric Acid is a colorless gas r26q times heavier 
than air ; it fumes strongly in damp air, combining with the 
moisture, and has a strongly acid reaction. It is very soluble 
in water, one volume of this liquid at 150 dissolving 454 Elementary Chemistry. 
89 
volumes of the gas ; this solution is the ordinary Hydro- 
chloric or Muriatic Acid of the shops. Under a pressure of 
40 ats. the gas forms a limpid liquid. The gas can be col- 
lected over mercury, and its solubility in water strikingly 
shown by allowing a few drops of water to ascend to the sur- 
face of the mercury in contact with the gas : a rapid rise of 
the mercury in the jar immediately occurs. A saturated solu- 
tion of hydrochloric acid in water has the specific gravity of 
1 *2r ; it fumes strongly in the air, and when heated in a re- 
tort, loses at first hydrochloric acid gas, but after a time an 
aqueous acid distils over at the ordinary atmospheric pres- 
sure, containing 20-22 per cent, of HC1, and boiling constant- 
ly at 1 io°. If the distillation be conducted under a diminished 
pressure, the acid boils constantly at a lower temperature, 
and attains a composition which is different for each boiling 
point; hence the constant acids thus obtained by boiling the 
solution of hydrochloric acid gas in water cannot be con- 
sidered as definite compounds of HC1 and water. This fact 
holds good for many other aqueous solutions of acids, &c., 
viz.: that residues constantly boiling at the same tempera- 
ture, and having constant compositions, are obtained on dis- 
tillation, the composition and boiling point varying, however, 
with the pressure under which the distillation has been con- 
ducted. 
Enormous quantities of Hydric Chloride (commonly called 
Muriatic Acid, from muria sea-salt) are obtained as a bye- 
product in the manufacture of sodium carbonate (see p. 162). 
More than 1,000 tons of this acid are made every week in the 
South Lancashire district alone. The acid thus produced is, 
however, very impure, having a yellow color, and contain- 
ing iron, arsenic, organic matter, and sulphuric acid in solu- 
tion. 
The arrangement represented, in Fig. 29 is adapted to 
show, that when gaseous hydric chloride is passed over 
heated manganese dioxide, water and chlorine gas are formed, 
thus : 
4 HC1 + MnOi = Cl2 + 2(H20) + MnCl2. 90 
Elementary Chemistry, 
If the gas is allowed to pass over the oxide contained in 
the first bulb before it is heated, no formation of water is 
noticed, and the red litmus paper in the bottle remains 
colored ; as soon as the oxide is heated, moisture is at once 
seen to be deposited in the second bulb, and the paper be- 
comes bleached, showing the presence of chlorine. The 
exact composition of hydric chloride is best determined by 
decomposing the aqueous acid by means of a current of 
voltaic electricity, by an arrangement similar to that shown 
Fig. 29. 
in Fig. 11, and collecting the gases (hydrogen and chlorine) 
evolved in a long tube after allowing the decomposition to go 
on for some time. If the tube thus filled be opened in the 
dark under a solution of potassium iodide, the solution will 
rise in the tube, the iodine being liberated, the chlorine com- 
bining with the potassium, until exactly half the tube is filled 
with liquid ; the remaining gas is found to consist of hydrogen. 
If the mixture of electrolytic gases, which can with care be 
sealed up in a strong tube, be exposed to the action of day- 
light, or of a bright artificial light, immediate combination of 
the two gases will ensue, and on opening the tube under water, 
this liquid will completely fill the whole of the tube, showing 
that the component gases were present in exactly the propor- 
tion needed to form hydrochloric acid. Elementary Chemistry. 
Compounds of Chlorine with Oxygen. 
Chlorine and Oxygen do not unite directly, but they may 
indirectly be made to form the following compounds, viz:— 
Compounds of Chlorine and Oxygen. Corresponding Acids. 
(1) Hypochlorous Oxide, CI2 O, yielding ■ 
(2) Chloric Tri-oxide, Cl2 O3, yielding . ■ 
(3) Chloric Tetroxide, CI2 04 . . . 
(4) No corresponding Oxide is known . - 
(5) No corresponding Oxide is known . - 
Hypochlorous A cid or | 
Hydric Hypochlorite j 
Chlorous A cid or | 
Hydric Chlorite | 
HCIO 
HCIO* 
No corresponding Acid is known. 
Chloric A cid or 
Hydric Chlorate 
Perchloric Acid or 
Hydric Perchlorate 
HCIO3 
HC1CM 
The oxides C1205 and CbOr, corresponding respectively to 
the two last acids, have not yet been prepared in the free 
state. 
Cl) 
Hypochlorous Oxide. Symbol q j- O, or C120. Combining 
Weight 87. Density 43'5. 
This body is obtained by the action of chlorine upon mer- 
curic oxide—the chlorine combining not only with the metal, 
but also with the oxygen, thus : 
Hg 0 + 2 Cb = C120 + Hg Cl2. 
Mercuric oxide, and chlorine, give hypochlorous oxide, and 
mercuric chloride. 
It is a colorless gas, which may be condensed by means of 
a freezing mixture to a red liquid, which is very explosive. 
It is soluble in water, forming a solution of hypochlorous 
acid, thus H20 + C120 = 2 HC10 : this action of water upon 
an oxide, forming a hydric salt or acid, is a very general 
reaction ; it occurred with nitric pentoxide N206 (N2Os + 
H20 = 2 NOaH, page 56), and with carbonic dioxide (C02 + 
H20 = H2COs, page 72), and we shall frequently meet with 
it hereafter. Elementary Chemistry. 
92 
Hypochlorous Acid, or Hydric Hypochlorite. Symbol 
HCIO. Combining Weight 52-5. 
This body may be obtained in solution in water by dis- 
tilling dilute solutions of sodium hypochlorite or calcium 
hypochlorite with dilute nitric acid. Thus : 
Na CIO + HNO3 = Na N03 + H CIO. 
Sodium hypochlorite and nitric acid give sodium nitrate 
and hypochlorous acid. 
It may be regarded as hypochlorous oxide in which one 
atom of chlorine has been replaced by one of hydrogen. 
When this atom of chlorine is replaced by metals, a series of 
salts called Hypochlorites is obtained. These are formed 
(together with chlorides) whenever chlorine gas acts upon the 
solution of certain metallic oxides in water, or on. the damp 
solid oxides. Thus when chlorine acts upon moist slaked 
lime, bleaching (a mixture of calcium hypochlorite 
and chloride) is produced; the reaction may be explained 
thus: 
2 Ca HaOj + 2 Cla — 2 Ha O -f- Ca Cla + Ca Ola Oj. 
Calcium hydrate and chlorine give water, calcium chloride, 
and calcium hypochlorite. 
This substance, so largely used for bleaching purposes, is 
prepared on the large scale by passing chlorine gas into 
spacious chambers, on the floors of which a layer of slaked 
lime two inches thick is laid ; the gas is all absorbed, and 
bleaching powder formed. When treated with a small quan- 
tity of a dilute acid, hypochlorous acid is liberated, and may 
be distilled over, whereby an aqueous solution is obtained as 
a colorless liquid, having a peculiar smell and bleaching prop- 
erties. If a larger quantity of acid be added, the hypochlor- 
ous acid itself is decomposed into chlorine and water, or 
hydrochloric acid and oxygen. Hence in the operation of 
bleaching, the goods are first dipped into a solution of bleach- 
ing powder, and then passed through a dilute acid, whereby 
hypochlorous acid is first formed and then decomposed, 
liberating chlorine in the fibre of the cloth ; the bleaching Elementary Chemistry. 
93 
effect is, therefore, only visible after the goods have been 
“soured,” or dipped in the acid. 
Chloric Trioxide, Symbol C1203, is produced by the deoxi- 
dation of chloric acid, HClOa ; it is connected with a series 
of salts called chlorites, just as hypochlorous oxide is with 
the hypochlorites ; thus, Sodium chlorite is NaC102. 
Chloric Tetroxide, Symbol C1204, is an explosive gas ob- 
tained by the action of sulphuric acid on potassium chlorate. 
Chloric Pent oxide, Symbol CI206, has not been as yet iso- 
lated ; but the acid derived from it is known, viz. : 
Chloric Acid. Symbol H C103. Combining Weight 
Certain metallic salts corresponding to this body (and termed 
chlorates) are obtained by the action of chlorine in excess 
upon the warm solution of the metallic oxide, thus: 
3 Cl2 + 6 KHO = KCIO3 + SKC1 + 3 H20. 
Chlorine, and potash, give potassium chlorate, potassium 
chloride, and water. 
The chlorate can be easily separated from the more solu- 
ble chloride by crystallization. Chloric acid (hydric chlorate) 
itself can be prepared by decomposing potassium chlorate by 
hydrofluosilicic acid, whereby an insoluble potassium com- 
pound is precipitated, and chloric acid remains in solution ; 
or by adding sulphuric acid to barium chlorate, insoluble, 
barium sulphate being precipitated, thus : 
Ba 2 CIO3 + H2 So* = Ba SO* + 2 (H CIO.). 
Chloric acid solution may be concentrated to a syrup, but 
it decomposes on further evaporation; it acts as a powerful 
oxidizing agent, and when dropped upon paper it produces 
ignition, parting with its oxygen. The chlorates also yield 
up all their oxygen on heating, and the potassium salt is used 
as a most convenient source of this gas. The composition 
of chloric acid is ascertained by determining the weight of 
oxygen, which potassium chlorate yields on heating (see ante, 
p. 12), together with the amount of chlorine contained in the 
residual potassium chloride. 94 
Elementary Chemistry. 
Chloric Heptoxide, Symbol C1207, is unknown as yet in the 
free state. Its corresponding acid is known, viz.: 
Perchloric Acid. Symbol HCIO4. Combining Weight 
100-5. When potassium chlorate is heated, it first fuses and 
begins to give off oxygen : at a certain point, however, the 
whole mass solidifies ; if the decomposition be stopped at this 
stage a new salt will be found to be contained in the residue, 
together with chloride and unaltered chlorate. This is termed 
Potassium perchlorate, and its composition is KC104. It 
may be easily separated from the chlorate by the action of 
hydrochloric acid, which decomposes this latter, but has no 
action on the perchlorate. Perchloric acid, HC104, can easi- 
ly be prepared from the potassium salt by the action of strong 
sulphuric acid. If a mixture of one part of the dry perchlo- 
rate and four of sulphuric acid be distilled in a retort, a color- 
less fuming liquid condenses in the receiver ; this is per- 
chloric acid, HCIO4. It has a specific gravity of 1-78 at 15°*5, 
and does not solidify at-35°. Perchloric acid is one of the 
most powerful oxidizing agents known; when thrown upon 
wood or paper it produces instant ignition, and when dropped 
on to charcoal it decomposes with a loud explosion. It com- 
bines with water to form a crystalline hydrate, HCIO4 + H2O, 
which when further diluted with water forms a thick oily 
liquid, boiling constantly at 203°, and containing 72-3 per 
cent, of HCIO4, and thus not corresponding to any definite 
hydrate. Perchloric acid is by far the most stable of the acids 
derived from chlorine. 
Compounds of Chlorine and Nitrogen. 
Chlorine combines with nitrogen, though only indirectly, to 
form a very remarkable compound, the composition of which 
has not been as yet determined. If chlorine gas is passed into 
a solution of ammonia, nitrogen, as we have seen, is liberated ; 
if an excess of chlorine be employed, drops of an oily liquid 
are seen to form, which, on being touched, explode with fear- Elementary Chemistry. 
95 
ful violence, so that the greatest caution must be used in 
manipulating even traces of this body. The explosive nature 
of this compound arises from the fact that its constituent ele- 
ments are very loosely combined, and separate with sudden 
violence. 
Compounds of Chlorine and Carbon. 
Chlorine and carbon unite to form four different com- 
pounds, which will be discussed under Organic Chemistry. 
LESSON XI. 
Bromine. Symbol Br. Combining Weight 80, Density Zo. 
This element, which closely resembles chlorine in its prop- 
erties and compounds, was discovered by Balard, in 1826, 
in the salts obtained by the evaporation of sea-water. It 
does not occur free in nature, and is, like chlorine, found com- 
bined with sodium and magnesium in the waters of certain 
mineral springs. In order to obtain pure bromine, use is 
made of the fact that free chlorine liberates bromine from its 
combinations with metals, forming a metallic chloride. The 
bromine thus set free may be separated by shaking the liquid 
up with ether, which dissolves the bromine, forming a bright 
red solution. On adding caustic potash to this ethereal solu- 
tion, the color at once disappears, the bromine becomes com- 
bined, forming potassium bromide, and bromate : on evapo- 
ration of the ether these salts remain, and after ignition (to 
decompose the bromate), the bromine can again be liberated 
by the action of sulphuric acid and manganese dioxide, 
exactly as in the case of chlorine. 
2 BrK + 2H2S04 + Mn02=2Br + K2SO4 + MnS04 + 2Ha0. 
Potassium bromide, and sulphuric acid, and manganese 9 6 
Elementary Chemistry. 
dioxide, give bromine, potassium sulphate, manganese sul- 
phate, and water. 
Bromine is a dark, reddish-black, heavy liquid (the only 
element liquid at ordinary temperatures besides mercury) : 
its specific gravity at 40 is 2‘966 ; it freezes at — 22“ to a black 
solid, and boils at 63°. It possesses a very strong, irritating 
smell, resembling that of chlorine a stink), and, when 
inhaled, acts as a strong poison : one part of bromine dissolves 
in about 30 parts of water at 15°; and this solution possesses 
bleaching powers, feebler, however, in action than those of 
chlorine. This bleaching action is caused by the oxidation of 
the coloring matter, bromine combining with the hydrogen of 
the water to form an acid called hydrobromic acid, correspond- 
ing in mode of formation and properties to hydrochloric acid. 
Hydrobromic Acid., or Hydric Bromide. Symbol HBr. 
Combining Weight 81. Density 4C5. 
Hydrogen and bromine do not unite together, even when 
placed in the sunlight, but they combine to form hydro- 
bromic acid when passed through a. red-hot porcelain tube. 
Hydrobromic acid is prepared by the action of acids (phos- 
phoric acid) on the bromides; it is a colorless gas, having a 
strong acid reaction, and fumes strongly in moist air; it is 
very soluble in water. When concentrated, the aqueous acid 
boils (under 760 mm. pressure) at 126°, and contains 47-8 per 
cent, of HBr. Two volumes of this gas contain one of 
bromine united with one of hydrogen. The aqueous acid 
neutralizes bases, forming the bromides and water. The gas 
liquefies at - 730. 
Co7npounds of Bromine with Oxygen. 
These are analogous to those of Chlorine, although not 
so numerous. 
Hypobro7?wus Oxide, Br20, is not known, but the cor- 
responding Hypobromous Acid, HBrO, is known, though Elementary Chemistry. 
97 
only in aqueous solution. It is obtained by the action of 
bromine water upon mercuric oxide ; like hypochlorous acid, 
it bleaches vegetable coloring matters by oxidation, hydro- 
bromic acid being formed. Brotnic Pentoxide, Br205, has 
not yet been isolated, but the corresponding Bromic Acid, 
HBr03, can be obtained by the action of chlorine upon 
bromine water, thus: 
Br + 3H2O + 5CI = 5HCI + HBrOa. 
In both its properties and composition it corresponds to 
chloric acid. Certain metallic bromates can be obtained, 
like the corresponding chlorates, by the action of bromine on 
the metallic oxides in aqueous solution. The best method of 
obtaining the bromates of the alkaline metals (potassium and 
sodium) consists in saturating a concentrated solution of the 
metallic carbonate with chlorine until carbonic acid begins to 
escape, and then adding bromine ; all the chlorine escapes, 
and solution of pure bromate remains. Hence it appears 
that bromine can displace chlorine from its compounds with 
oxygen, whilst chlorine can liberate bromine from its com- 
pound with hydrogen. The bromates are decomposed by 
heat in the same way as the chlorates. 
Perbromic Acid., or Hydric Perbromate, HBrCb, has been 
obtained by the action of bromine upon perchloric acid, 
HCIO4. 
Iodine. Symbol I. Combining Weight 127. Density 127. 
Iodine likewise occurs in sea-water, and is obtained from 
kelp, the ash of certain seaweeds, in which it is found com- 
bined with sodium and magnesium, forming compounds 
called Iodides. It was discovered in 1812 by Courtois. 
Iodine is obtained from kelp by exactly the same process as 
that by which chlorine and bromine are obtained from chlo- 
rides and bromides, viz. by heating with sulphuric acid and 
manganese dioxide, bodine is thus liberated in the form of a 98 
Elementary Chemistry. 
deep violet-colored vapor, which condenses to a dark gray 
solid, with bright metallic lustre. Iodine melts at 1150, and 
boils above 200°, and has a specific gravity of ; it gives 
off a perceptible amount of vapor at the ordinary temperature, 
and possesses a faint, chlorine-like smell. Water dissolves 
a very small quantity of iodine ; but, in presence of a soluble 
iodide, it is freely dissolved, forming a deep red or brown 
solution: it is easily soluble in alcohol and other organic 
liquids. Iodine does not possess such active properties as 
either of the preceding elements, its solution does not bleach 
organic coloring matters, and it is liberated from its com- 
pounds by both bromine and chlorine. Free iodine forms a 
remarkable compound with starch, of a splendid blue color, 
and by this means the minutest trace of this substance can 
be detected. To apply this test, one drop of potassium 
iodide solution is added to starch paste largely diluted with 
water ; no blue color is observed until the iodine is set free 
by the addition of a drop or two of chlorine-water, when a 
deep blue coloration is instantly perceived. Iodine acts as a 
powerful poison, but, given in small quantities, it is much used 
as medicine. 
Hydriodic Acid, or Hydric Iodide. Symbol HI. Combin- 
ing Weight 128. Density 64. Iodine and Hydrogen may 
be made to unite with each other by heating them together ; 
hydriodic acid is liberated when dilute sulphuric acid acts on 
an iodide. This substance is, however, best prepared by 
acting upon the phosphoric iodides with water, thus : 
PI, + 3H2O = 3HI + H, PO,. 
Phosphoric tri-iodide and water produce hydriodic acid and 
phosphorous acid. 
Hydriodic acid is a colorless gas, possessing a strong acid 
reaction, and fuming strongly in the air; it is very soluble 
in water, yielding a solution which boils at 1270, and contains 
57 per cent, of HI. The gas liquefies under pressure, and 
solidifies at - 550. An analysis of this gas shows that hydri- 
odic acid (like hydrochloric) is composed of one volume of Elementary Chemistry. 
99 
hydrogen and one of iodine, forming two volumes of hydriodic 
acid. 
Compounds of Iodine with Oxygen. 
Iodine, when treated with caustic alkaline solutions, does 
not yield bleaching liquors ; nor is there any compound cor- 
responding to hypochlorous acid known in the iodine series. 
It forms, however, two important acids, iodic and per-iodic 
acids, corresponding respectively with chloric and perchloric 
acids; the oxide, I2O7, corresponding with the latter, is also 
known. Iodicpentoxide, LOs, is obtained as a white crystal- 
line solid by heating iodic acid, HIO3, to 170°. 
Iodic Acid, or Hydric lodate. Symbol HI03. Combining 
Weight 176. This acid, which corresponds closely with 
chloric acid, may be obtained by the direct oxidation of iodine 
by nitric acid, and also by acting upon iodine water with 
chlorine, thus : 
I + 3H2O + 5CI = HIOs + 5HCI. 
Iodine, water, and chlorine, yield iodic acid and hydro- 
chloric acid. 
The alkaline iodates are formed (together with the iodides 
of the metals employed) like the chlorates and bromates, by 
dissolving iodine in the caustic alkalies. 
6i + 6HKO = KIOs + SKI + 3H2O. 
Iodine and caustic potash, give potassium iodate, potassium 
iodide, and water. 
The whole of the iodine is converted into iodate if chlorine 
gas be passed into the solution, thus ; 
I + 6KHO + 5CI = KIO3 + SKC1 + 3H2O. 
Iodine, caustic potash, and chlorine, yield potassium iodate, 
potassium chloride, and water. 
Hence we see that oxygen combines with iodine to form an 
iodate in preference to forming a chlorate with chlorine. The 
iodates of the alkaline metals decompose on heating like the 100 
Elementary Chemistry. 
corresponding chlorates, yielding oxygen and an iodide, 
whereas the iodates of the heavy metals yield the metallic 
oxides, iodine, and oxygen. 
Iodic Heptoxide, I207, has recently been prepared. 
Per-iodic Acid., HI04, or Hydric Per-iodate, can be obtained 
from the corresponding perchloric acid by the addition of 
iodine. 
Fluorine. Symbol F. Combining Weight ig. 
This element occurs combined with the metal calcium, 
forming calcium fluoride CaF2, or fluorspar, a mineral crys- 
tallizing in cubes and found in Derbyshire ; it also exists in 
large quantities in cryolite (3 NaF + A1FS), a mineral found 
in Greenland, whilst it has been detected in minute quantities 
in the teeth, and even in the blood of animals. Fluorine is 
remarkable as forming no compounds with oxygen, and as 
being extremely difficult to prepare in a pure state. Many 
unsuccessful attempts have been made to obtain fluorine, but 
none of the methods which yield chlorine, bromine, or iodine 
give any result. By the action, however, of dry iodine upon 
dry silver fluoride, it appears that fluorine has been isolated, 
and it is found to be a colorless gas which does not act upon 
glass, and is absorbed by caustic potash with the formation 
of potassium fluoride and hydric dioxide. 
2 KHO + Fa = 2 KF + HaOa. 
Hydrofluoric Acid., or Hydric Fluoride. Symbol HF. 
Combining Weight 20. Density 10. 
This gas corresponds in composition to the hydrogen com- 
pounds of the three preceding elements, and may be obtained 
in an exactly similar manner by the action of sulphuric acid 
upon calcium fluoride, thus : 
Ha SO4 + CaFa = 2 HF + Ca S04. 
Sulphuric acid, and calcium fluoride, give hydrofluoric acid 
and calcium sulphate. 
Hydrofluoric acid gas must be prepared in a leaden or Elementary Chemistry. 
101 
platinum vessel (Fig. 30), as glass is rapidly attacked by the 
vapor. The colorless gas thus obtained fumes strongly in 
the air; if it be passed into a metallic tube (Fig. 30) placed 
in a freezing mixture of the temperature of -20°, a liquid is 
formed ; this liquid is strong aqueous hydrofluoric acid : it 
appears doubtful whether the dry acid HF has been obtained 
in the liquid state. The strong acid acts very violently upon 
the skin, producing painful wounds ; and the fumes of the gas 
are likewise dangerous from their corrosive power. When 
brought into contact with water the strong acid dissolves 
Fig. 30. 
with a hissing noise; this aqueous acid attains a constant 
boiling point under the ordinary atmospheric pressure, when 
the liquid contains 37 per cent, of HF. 
The most remarkable property of hydrofluoric acid is its 
power of etching upon glass ; this arises from the fact that 
fluorine forms, with the silicon contained in the glass, a vola- 
tile compound called Silicic Fluoride (see p. 123). This etching 
serves as a very delicate test of the presence of fluorine, and 
is effected in a very simple manner by covering a watch-glass 
with a thin coating of wax, removing a portion by means of a 
sharp point, and then exposing the glass for a short time to 
the vapor of hydrofluoric acid given off by heating the materials 
in a small leaden saucer; on removing the wax with a little 
turpentine, the marks on the glass will be distinctly visible. 
The solution of hydrofluoric acid in water is also used for the 
purpose of etching on glass. Fluorspar is used in metal- 
lurgy operations as a flux, whence its name (Jluo, to flow). Elementary Chemistry. 
102 
The members of the foregoing group of elements exhibit 
certain remarkable relations among themselves, especially a 
gradation in properties. Thus chlorine is a gas, bromine a 
liquid, and iodine a solid, at ordinary temperatures ; the spe- 
cific gravity of liquid chlorine is 1*33, of bromine 2-97, and of 
iodine 4-95 ; liquid chlorine is transparent, bromine but 
slightly so, and iodine is opaque. The combining weight, 
and, therefore, the density of bromine, is nearly the mean of 
_[_ 127 
those of chlorine and iodine, J = 81*25 ; and in its 
general chemical deportment bromine stands half-way between 
the other two elements. The property which distinguishes 
these substances from the rest of the elements is the power 
of forming, with hydrogen, compounds containing equal 
volumes of the constituent gases united without condensa- 
tion. 
LESSON XII. 
Sulphur. Symbol S. Combining Weight 32. Density 32. 
Sulphur occurs both free and combined in nature; it is 
found free in certain volcanic countries, especially in Sicily 
and Iceland, and occurs crystallized in yellow transparent 
crystals in the form of rhombic octahedra (Fig. 31); it exists 
Fig. 31. Elementary Chemistry. 
103 
in combination with many metals, forming compounds termed 
Sulphides, which constitute the common ores from which the 
metals are usually obtained. Thus PbS, lead sulphide, or 
Galena; Zn S, zinc sulphide, or Blende; and Cu S, copper 
sulphide, are the substances from which those metals are 
generally procured. Sulphur also is found in nature, com- 
bined with metals and oxygen, to form a class of salts called 
Sulphates ; of these, calcium sulphate or gypsum, barium sul- 
phate or heavy spar, sodium sulphate or Glauber’s salt, occur 
in the largest quantity. Sulphur likewise occurs combined 
with hydrogen as a gas called Hydric Sulphide, or Sulphu- 
retted Hydrogen, H2S, in the waters of certain springs, as at 
Harrogate. In order to obtain pure sulphur, the mineral con- 
taining the crude substance mixed with earthy impurities is 
heated in earthenware pots (Fig. 32); the sulphur distils over 
Fig. 32. 
in the form of vapor, which is condensed in similar pots 
placed outside the furnace. When brought to this country, 
the sulphur thus obtained is refined or purified by subjecting 
it to a second distillation. If the vapor of sulphur is quickly 104 
Elementary Chemistry. 
cooled below its melting-point, it solidifies in the form of a 
fine crystalline powder called Flowers of Sulphur, exactly as 
aqueous vapor, when cooled down below the freezing point of 
water, deposits as snow. When sulphur is gently heated it 
melts, and may be cast into sticks, and is then known as 
brimstone or roll sulphur. 
Sulphur exists in three modifications : the first is that in 
which sulphur crystallizes in nature, and the other two are 
obtained by melting sulphur. If melted sulphur be allowed to 
cool slowly, it crystallizes in long, transparent, needle-shaped, 
prismatic crystals, which are quite different in form from the 
natural crystals of sulphur, and have the specific gravity of 
I '98 ; whereas the specific gravity of the crystals of na- 
tive sulphur is 2'oy. These transparent crystals become 
opaque after exposure to the air for a few days, owing to each 
crystal splitting up into several crystals of the natural, octahe- 
dral, or permanent form. The third allotropic modification 
of sulphur is obtained by pouring melted sulphur heated to 
230° into cold water; the sulphur thus forms a soft tenacious 
mass resembling caoutchouc, and has a specific gravity of 
1 '96. This form of sulphur is, however, not permanent; in a 
few hours, at the temperature of the air, the mass assumes the 
ordinary brittle form of the element, while, if heated to ioo°, 
it instantly changes to the brittle form, 'and thereby evolves 
so much heat as to raise its temperature up to m°. These 
peculiar modifications become apparent when sulphur is 
heated ; thus, sulphur melts, to begin with, at 115°, and forms 
an amber-colored mobile liquid ; as the temperature rises, the 
liquid becomes dark-colored, and attains the consistency of 
thick treacle, so that at about 230° it can scarcely be poured 
out of the vessel; heated above 250° it again becomes fluid, 
and remains as a dark reddish-black-colored thin liquid, until 
the temperature rises to 490°, when it begins to boil and gives 
off a red-colored vapor. 
Sulphur is an inflammable substance, and when heated in 
the air or in oxygen, burns with a bluish flame, combining 
with the oxygen to form sulphuric dioxide (often called sul- Elementary Chemistry. 
105 
phurous acid), S02, which is given off as a gas possessing the 
peculiar and well-known suffocating smell which is evolved 
when a common lucifer match is burnt. Sulphur is insoluble 
in water and most organic liquids, but both the natural octahe- 
dral variety, and the other crystalline (or prismatic) variety, 
dissolve freely in carbonic di-sulphide, CS2, whilst the tena- 
cious form of sulphur is insoluble in this liquid. When de- 
posited from solution in carbonic di-sulphide, sulphur crystal- 
lizes in the ordinary natural or octahedral form. 
Compounds of Sulphur and Oxygen. 
Two compounds of sulphur and oxygen are known in the 
free state, viz. the di-oxide, S02, and the tri'oxide, S03: whilst 
acids corresponding to several others are known, as are also 
several extensive series of well defined metallic salts thence 
derived. The following table shows the composition of seven 
sulphur oxacids ; the first three on the list are important com- 
pounds, the remaining bodies are but little known, and do not 
as yet serve any purpose in the arts or manufactures. These 
compounds exhibit in a striking manner the law of multiple 
combining proportions enumerated by Dalton. (See ante, 
p. 50.) 
Hydric Sulphite or Sulphurous Acid H2S Os 
Hydric Sulphate or Sulphuric Acid HaS O4 
Hydric Hyposulphite or Hyposulphurcus Acid H SsOs 
Hydric Dithionate or Dithionic Acid H2S2O6 
Hydric Trithionate or Trithionic Acid HaSsOs 
Hydric Tetrathionate or Tetrathionic Acid HaSjOs 
Hydric Pentathionate or Pentathionic Acid H2S5O6 
Sulphuric Dioxide or Sulphurous Acid. Symbol SOa. 
Combining Weight 64, Density 32. 
This gas is obtained when sulphur is burnt, and it is given 
off in large quantities from volcanic craters ; it may be pre- 
pared more conveniently on the small scale by removing the 
elements of water, and one additional atom of oxygen from Elementary Chemistry. 
sulphuric acid by heating along with it the metals copper or 
mercury, thus : 
Cu + 2H3 S04 = SOn + Cu S04 + 2Ha0. 
Copper, and sulphuric acid, yield sulphuric dioxide, copper 
sulphate, and water. 
The gas thus given off may be washed to purify it and then 
collected over mercury or by displacement. It is a colorless 
gas, possessing a suffocating smell of burning sulphur ; it is 
2-247 times heavier than air, and may be condensed to a col- 
orless liquid by cooling down to - io° under the ordinary 
atmospheric pressure ; when cooled below -76° the liquid 
freezes to a transparent solid. The arrangement for liquefy- 
ing the gas is seen in Fig. 33 : it consists of the usual evolu- 
Fig. 33- 
tion flask and washing bottle, which is connected with a spiral 
glass tube surrounded by a freezing mixture of salt and 
pounded ice. The gas condenses in this tube and falls down 
into the small flask placed below, which is also placed in a 
freezing mixture. When a sufficient quantity of the liquid has 
been collected, the neck of the flask can be sealed up by the Elementary Chemistry. 
107 
blowpipe at the narrow part, and the liquefied sulphuric 
dioxide preserved. This liquid evaporates very quickly when 
brought into the air, and the heat which thus becomes latent 
is so considerable, that the temperature may in this way be 
reduced to-6o°; this is easily shown by pouring some of the 
liquid upon the bulb of an alcohol thermometer which has 
been wrapped in cotton wool. 
Sulphuric dioxide, like all other gases which are easily 
condensed, exhibits considerable deviation from Boyle’s law 
of pressures, occupying for equal increments of pressure less 
space than air under the same conditions ; this difference 
becoming larger the lower the temperature. The volume of 
this gas formed by the combustion of sulphur is found to be 
exactly the same as that of the oxygen employed. Hence, 
as the density of sulphuric dioxide is 32, it contains equal 
weights of its constituent elements, 1 volume of sulphur 
uniting with 2 volumes of oxygen to give 2 volumes of the di- 
oxide. 
Sulphuric dioxide is very soluble in water, 1 volume of 
water at io° dissolving 51 ‘38 volumes, and at 20° 36-22 vol- 
umes of this gas. The solution of the gas in water consists 
(like that of carbonic dioxide, p. 71) of di-hydric sulphite or 
true sulphurous acid, H2 S03: but this substance is decom- 
posed on boiling the liquid, water and sulphurous dioxide 
being reproduced, this latter escaping as a gas. If the solu- 
tion of this gas in water be cooled below 5% a crystalline 
hydrate of sulphurous acid separates out, having the composi- 
tion H2 S03 -j- 14 h2o. 
Sulphurous acid is really the hydrogen salt in a series of 
compounds called sulphites ; these compounds, however, are 
easily decomposed by the stronger acids, sulphurous dioxide 
being liberated as a gas. This substance is largely used as a 
bleaching agent, especially for silk and woollen goods which 
cannot be bleached by chlorine ; it is also employed as an 
antichlor for the purpose of getting rid of the excess of 
chlorine present in the bleached rags from which paper is 
made. The great value of sulphurous dioxide in the arts is in Elementary Chemistry. 
the manufacture of sulphuric acid or oil of vitriol, and for this 
purpose enormous quantities of the dioxide are used. 
Sulphurous acid, H2 S03, like carbonic acid, H2 C03, is a 
dibasic acid, that is, it contains two atoms of hydrogen, both 
of them being capable of being replaced by metals: thus two 
classes of salts are derived ; the so-called acid salts, where 
only one atom of hydrogen has been replaced, and the neutral 
salts, where both atoms have been replaced by a metal. Thus 
Hydric Potassium Sulphite, HK S03, is an acid salt, and 
Dipotassium Sulphite, K2 S03, is a neutral salt. Similarly, 
we have Hydric Potassium Carbonate, HK C03, and Dipo- 
tassium Carbonate, K2 C03. 
In its bleaching action, sulphurous dioxide acts in a manner 
exactly opposite to that in which chlorine acts, inasmuch as 
it unites with the oxygen of the water or coloring matter 
present, forming sulphuric acid and liberating the hydrogen ; 
so that sulphurous acid bleaches by acting as a reducing or 
deoxidizing agent, whereas chlorine bleaches by oxidation : 
similarly, its action as an antichlor depends on the formation 
of sulphuric and hydrochloric acids, thus : 
S02 + 2 H20 + 2C1 = H2 SO4 + 2HCI. 
LESSON XIII. 
Sulphuric Trioxide, or Sulphuric Anhydride. Symbol 
S03. Combining Weight 80. Density 40. 
Sulphuric dioxide does not, under ordinary circumstances, 
combine directly with oxygen to form S03, but if these two 
dry gases be passed together over heated and finely divided 
metallic platinum, union takes place, and dense white fumes 
of the sulphuric trioxide are evolved, condensing to white 
silky needles. These crystals melt at 290 and boil at 46°, 
yielding a colorless vapor, which when passed through a red- Elementary Chemistry. 
hot tube is decomposed into two volumes of sulphuric dioxide 
and one volume of oxygen. Sulphuric trioxide does not 
redden litmus paper, and may be moulded by the fingers with- 
out charring the skin : when brought into contact with water, 
the two substances combine with great force, forming sul- 
phuric acid, H2SO4, hissing as a red-hot iron would do. The 
combination thus formed cannot be separated again into sul- 
phuric trioxide and water by boiling. The trioxide may like- 
wise be prepared by distilling Nordhausen fuming sulphuric 
acid (see below). 
Sulphuric Acid., or Di-hydric Sulphate. Combining 
Weight 98. 
This substance is the most important and useful acid 
known, as by its means nearly all the other acids are prepared, 
and also because it is very largely used in the arts and manu- 
factures, for a great variety of purposes. So valuable are the 
applications of this acid, that the quantity now manufactured 
in the South Lancashire district alone exceeds 3,000 tons per 
week. Indeed, it has been truly said, that the commercial 
prosperity of a country may be judged of with great accura- 
cy by the amount of sulphuric acid which it consumes. 
Sulphuric acid was first prepared by distilling a compound 
of iron, oxygen, sulphur and water, called ferrous sulphate or 
green vitriol. The acid thus obtained is known as fuming or 
Nordhausen acid, and consists of a mixture of dihydric sul- 
phate and sulphuric trioxide, H2S04 + S03. This plan of 
preparation has, however, long been superseded by the follow- 
ing more convenient method, which depends upon the fact, 
that although sulphuric dioxide does not combine with free 
oxygen and water to form sulphuric acid, it is capable of 
taking up the oxygen when the latter is united with nitrogen 
in the form of nitric trioxide, No03, thus : 
S02 + H20 + N203 = H2S04 + N202. 
Sulphuric dioxide, water, and nitric trioxide, yield sul- 
phuric acid and nitric oxide. Elementary Chemistry. 
The nitric oxide formed in this decomposition takes up an- 
other atom of oxygen from the air, becoming N203, and this 
is again able to convert a second molecule of SO? with H20 
into H2SO4,* being a second time reduced to N202, and 
ready again to take up another atom of oxygen from the air. 
Hence it is clear that the N202 acts simply as a carrier of 
oxygen between the air and the S02 ; an indefinitely small 
quantity of this nitric trioxide being, therefore, theoretically 
Fig. 34- 
able to convert an indefinitely large quantity of sulphurous 
dioxide, water, and oxygen into sulphuric acid.f 
This process is carried on, on the large scale, in chambers 
made of sheets of lead (often of a capacity of 50,000 or 100,000 
* A molecule is a group of atoms forming the smallest portion of a chemical 
substance, either simple or compound, that can be isolated, or that can exist alone ; 
it is the smallest amount of substance that can enter into any reaction or be gen- 
erated by it; an atom being the smallest portion of an element that can exist in a 
compound body as a mass indivisible by chemical forces ; thus the molecule of 
water H? O contains 2 atoms of hydrogen. 
t There is some doubt respecting the actual decomposition occurring in the 
leaden chamber, and the above must be taken only as a general explanation of 
what goes on. If the supply of steam be insufficient, a solid compound of nitric 
tetroxide, sulphuric dioxide, and water is formed, which is decomposed, on addi- 
tion of water, into sulphuric acid and nitric oxide. This substance, which has been 
called the crystals of the leaden chamber., is supposed by some to play an important 
part in the formation of sulphuric acid. Elementary Chemistry. 
111 
cubic feet), into which the above-mentioned materials are 
brought. Fig. 34 exhibits the construction of such a sul- 
phuric acid chamber. The sulphuric dioxide is procured 
either by burning sulphur in a current of air, or by roasting a 
mineral called iron pyrites (a compound of sulphur and iron, 
FeS2) in a suitable furnace, AA, Fig. 34. The sulphur of the 
pyrites burns away, and the gaseous product is led, together 
with atmospheric air, into the chamber, whilst ferric oxide, 
Fe2Os, remains behind in the furnace. A small stove (B), 
containing nitre, is placed in the hinder part of the furnace, 
where this salt is decomposed by the action of the sulphuric 
dioxide, an alkaline sulphate being formed whilst nitrous 
fumes pass with the other gases into the chamber. Jets of 
steam are also blown into the chamber from a boiler (C) at 
various points, and a thorough draught is maintained by con- 
necting the end of the chamber with a high chimney. The 
sulphuric acid, as it forms, falls on to the floor of the chamber, 
and when the process is working properly, it is continually 
drawn off, attaining a specific gravity of about r6o, whilst the 
waste gases passing out of the chamber should contain 
nothing but nitrogen and small quantities of nitric oxide. In 
order to obtain from this weak chamber-acid the pure dihy- 
dric sulphate, H2SO4, the excess of water must be removed 
by evaporation ; this is conducted, on the large scale, first, 
by heating the chamber-acid in open leaden pans until the 
specific gravity rises to 172, when the acid is known as the 
brown oil of vitriol of commerce, and then further concen- 
trated in vessels of glass, or of platinum (as lead is attacked 
by the strong acid), until its maximum strength and specific 
gravity is attained. The dihydric sulphate thus obtained is a 
thick oily liquid, boiling at about 338°,* and freezing at io0,8 ; 
its specific gravity at o° is r8s4- It combines with water 
with great force, absorbing moisture rapidly from the air ; 
* When boiled, dihydric sulphate undergoes a slight decomposition, sulphuric 
trioxide being evolved, and an acid remaining behind which contains only g8’5 
of HaSOl, and which at 338° C. may be boiled down without further decompo- 
sition. 112 
Elementary Chemistry. 
hence it is used in the laboratory as a drying agent. Great 
heat is evolved when this acid is mixed with water, and care 
must be taken to bring these two liquids together gradually, 
otherwise an explosive combination may ensue. Many or- 
ganic bodies, such as woody fibre and sugar, are completely 
decomposed and charred by strong sulphuric acid, whilst 
others, such as alcohol, oxalic and formic acid, are split up 
into other compounds by the withdrawal of the elements of 
water by this acid. 
One molecule of dihydric sulphate unites with one of water 
to form a compound, H2S04, + H20, which can be obtained 
pure by cooling a mixture of acid and water, having a specific 
gravity of 178 down to 7°C, at which temperature rhombic 
crystals of the hydrated acid are formed. The sulphuric acid 
of commerce frequently contains large quantities of impurities, 
especially lead sulphate, from the chamber, and frequently 
arsenic from the pyrites, and nitric acid, as well as the lower 
oxides of nitrogen. In order to free the acid from these 
impurities, it must be distilled and subjected to other treat- 
ment, for a description of which the reader is referred to the 
larger treatises. At high temperatures sulphuric acid decom- 
poses into sulphuric dioxide, S02, oxygen, O, and water, 
H20 ; thus, if a current of the acid be allowed to flow on to 
red-hot bricks, and the gases resulting from the decomposition 
passed through water, the sulphuric dioxide will be completely 
absorbed, and a supply of pure oxygen obtained. Dihydric 
sulphate is, as its name implies, a dibasic acid, i.e. it contains 
two atoms of hydrogen, either or both of which can be replaced 
by an equivalent quantity of a metal. As with sulphurous 
acid, in the case of the alkaline metals, we have two salts, 
thus—KHSO4 and K2S04, potassium being mon-atomic; that 
is, one atom of potassium is capable of replacing one of 
hydrogen. As, however, most of the other metals are di-atomic 
—i.e. one atom of metal is capable of replacing two atoms of 
hydrogen—we have only one sulphate of these metals ; thus 
barium sulphate is Ba S04, where Ba = H2: so copper sul- 
phate is CuS04, where Cu = H2. Barium and lead sulphates Elementary Chemistry. 
113 
are insoluble in water; hence soluble salts of these metals 
are used as tests of the presence of a sulphate ; calcium, 
strontium, and potassium sulphates are but slightly soluble in 
water, while the other sulphates are easily soluble. 
Some sulphates crystallize as anhydrous salts, such as 
K2SO4, dipotassium sulphate ; Ba S04, barium sulphate ; and 
AgaSO*, silver sulphate ; while others require water to retain 
their crystalline form, and this water is termed water of crys- 
tallization. The crystals of iron sulphate, or green vitriol, 
and of zinc sulphate, or white vitriol, contain seven molecules 
of water in the solid form; whilst copper sulphate, or blue 
vitriol, requires but five molecules to preserve its crystalline 
form. Thus— 
Fe SO4 -f- 7H2O , f— cr\ 1 - u a 
V CA T Lit and Cu SO4 + 5 H20 
Zn S04 + 7H20 j 
Hyposulphurous Acid., or Hydric Hyposulphite, is not 
known in the free state. The formula of a metallic hypo- 
sulphite, such as that of sodium, is Na2 S2 03 ; this also con- 
tains five molecules of water of crystallization ; it is largely 
used in photography for the purpose of fixing the image, the 
salt possessing the property of dissolving the silver salts 
which have been unacted on by the light. This useful salt is 
prepared by passing a current of sulphuric dioxide into a 
solution of sodium sulphide, and purifying by crystallization 
the sodium hyposulphite obtained. 
Sulphuric trioxide combines directly with hydrochloric acid 
to form a compound, which is interesting in a theoretical point 
of view; viz. chlor-hydrosulphuric acid, HC1S03. Sulphuric 
dioxide unites with chlorine to form stdphuryl chloride, Cl2 
S02. The first acid is really sulphurous acid, with one atom 
of hydrogen replaced by chlorine. 
Compounds of Sulphur and Hydrogen. 
Two of these are known, viz.-dihydric sulphide, H2S, and 
hydric persulphide, H2S2. 114 
Elementary Chemistry. 
Dihydric Sulphide, or Sulphuretted. Hydrogen. Symbol 
H2S. Combining Weight 34. Density 17. 
This gas is best prepared by the action of dilute sulphuric 
acid upon iron sulphide, FeS, iron sulphate being also formed 
thus— 
FeS + H2S04 = FeS04 + H2S, 
where two atoms of hydrogen change place with one of dia- 
tomic iron. Fig. 35 represents a convenient form of apparatus 
for the production and purification of this gas. It may be 
collected over warm water, and is a colorless gas, possessing 
the peculiar odor of rotten eggs ; it burns on application of a 
light with a bluish flame, forming water and sulphuric dioxide. 
When inhaled, it acts as a poison on the animal economy, 
even if diluted with large quantities of air. Sulphuretted 
hydrogen gas dissolves in water to a considerable extent, 
Fig. 35- 
imparting its peculiar smell and a slightly acid reaction to 
the water. One volume of water at 0° dissolves 4'37 volumes 
of the gas, whilst at 15° volumes are soluble. Exposed 
to a temperature of -74°, this gas condenses to a colorless, 
mobile liquid, which, when further cooled to -85°, freezes to 
a transparent, ice-like solid. Under a pressure of about 
seventeen atmospheres, this gas liquifies at the ordinary 
temperature of the air. Sulphuretted hydrogen occurs free 
in nature in volcanic gases, as well as in the water of certain Elementary Chemistry. 
115 
springs ; thus Harrogate waters owe their peculiar odor and 
medicinal power to the presence of this gas. It is likewise 
generated by the putrefaction of animal matters, such as albu- 
men, or the white of eggs, which contains sulphur; also by 
the deoxidation of sulphates in presence of decaying organic 
matter. 
The composition of sulphuretted hydrogen may be ascer- 
tained either by heating a small piece of metallic tin in a 
known volume of the gas, when tin sulphide will be formed, 
and hydrogen liberated; or by decomposing the gas by 
means of a red-hot platinum wire, when the whole of the sul- 
phur is deposited, and hydrogen set free. In both cases, the 
volume of hydrogen obtained is found to be equal to that of 
the gas employed ; and hence 2 volumes of sulphuretted 
hydrogen, weighing 34, consists of 2 volumes of hydrogen, 
weighing 2, and 1 volume of sulphur vapor, weighing 32. 
Sulphuretted hydrogen is an invaluable re-agent in the 
laboratory, as by its means we are enabled to separate the 
metals into groups. If we pass a current of this gas through 
a solution of a copper salt, to which a small quantity of acid 
has been added, we obtain an immediate precipitate of copper 
sulphide ; if we do the same with a solution of an iron salt, 
we get no such precipitate, because iron sulphide is soluble 
in an acid ; but on the addition of an alkali, iron sulphide is 
at once precipitated. We may thus divide the metals into 
groups ; first, those which, like copper, are precipitated by 
sulphuretted hydrogen from an acid solution, or the copper 
group; second, those which are not precipitated by sulphu- 
retted hydrogen in an acid solution, but which are so precipi- 
tated in an alkaline one, or the iron group j and third, those 
which are in no case precipitated by this re-agent, as their 
sulphides are soluble either in water, acids, or alkalies: to 
this group belong the metals of the alkalies and alkaline 
earths. 
Hydric Persulphide, or Dihydric Disulphide, H2Su. This 
substance is obtained by pouring a solution of calcium disul- 
phide into hydrochloric acid ; an oily liquid falls to the bottom Elementary Chemistry. 
of the vessel, which is the body in question. Hydric disul- 
phide closely resembles hydric dioxide in many of its proper- 
ties ; it bleaches, and readily decomposes into sulphur and 
sulphuretted hydrogen. Owing to the solubility of sulphur 
in this body, and the difficulty of purifying it, its composition 
is not accurately ascertained* 
Carbonic Disulphide. Symbol CS2. Combining Weight 
76. Density 38. 
If the vapor of sulphur be passed over red-hot charcoal, 
a volatile compound, CS2, is formed, which may be con- 
densed to a heavy, colorless liquid, possessing a peculiarly 
disagreeable smell, boiling at 43°‘3, and having a specific 
gravity of i'2"/2. Carbonic disulphide is very inflammable, 
its vapor igniting at 149° when mixed with air, forming car- 
bonic dioxide, and sulphuric dioxide (sulphurous acid), S02. 
It is insoluble in water, but acts as a solvent upon gums, 
caoutchouc, sulphur, and phosphorus ; its vapor is, however, 
very poisonous, and it must be employed with caution. 
A remarkable analogy is presented by the foregoing sulphur 
compounds and the corresponding bodies in the oxygen 
series : thus water, H20, and sulphuretted hydrogen, H2S ; 
hydric dioxide, H202, and hydric disulphide, H2S2 ; carbonic 
dioxide, C02, and carbonic disulphide, CS2, possess not only 
an analogous composition, but similar chemical properties, 
whilst similar relations are seen in many of the compounds of 
these bodies. 
Chlorine and Sulphur unite directly to form two com- 
pounds, S2CI2 and SC12 ; they are formed by leading a cur- 
rent of chlorine gas over melted sulphur, and are volatile 
liquids, the first boiling at 138°, and the second at 64°. Elementary Chemistry. 
LESSON XIV. 
Selenium.* Symbol Se. Combining Weight 79’5- 
Density 79-5. 
Selenium is an element which closely resembles sulphur in 
its properties, but it occurs in very small quantities ; it was 
discovered by Berzelius, who found it accompanying sulphur 
in certain varieties of Swedish pyrites. Selenium also occurs 
free in nature, and is found in combination with metals in 
certain rare minerals. Like sulphur, it is capable of existing 
in various allotropic modifications, one of which is crystal- 
line, the other vitreous ; the crystalline form is obtained when 
selenium is deposited from solution in carbonic disulphide; 
the vitreous modification results from the cooling of melted 
selenium. The specific gravity of the former variety is 4 5 ; 
that of the latter, 47. Crystalline selenium melts at 217°, 
and boils at a temperature below a red heat, giving off a deep 
yellow vapor ; vitreous selenium softens at a temperature a 
little above the boiling point of water, and remains in a plas- 
tic condition for some time. In a finely divided state, and 
when seen by transmitted light, selenium has a red color. It 
burns in the air with a bright blue flame, which, when ex- 
amined by means of the spectroscope (p. 222), exhibits a series 
of magnificent and characteristic bands. The smell of burn- 
ing selenium is very peculiar, resembling that of rotten cab- 
bages, and is due to the formation of an oxide, the composi- 
tion and properties of which are, however, as yet unknown. 
Selenium forms two well-defined oxides, selenic dioxide, SeOj, 
and selenic trioxide, Se03 ; this latter, however, has not as 
yet been isolated, but the acid and salts corresponding with 
it, and those corresponding with the dioxide, are well known, 
and correspond exactly with the analogous sulphites and sul- 
phates ; they are hence called selenites and selenates. 
Selenic Dioxide. Symbol Se02. Combining Weight 
* From SeXiji'i;, the moon. 118 
Elementary Chemistry. 
ill -5. This compound is formed when selenium is burnt in 
the air, or in pure oxygen. It may be prepared, too, by 
oxidizing selenium in nitric acid or aqua regia. Selenic 
dioxide is a white crystalline mass, capable of dissolving in 
water, and thus forming selenious acid., H2 SO3. From this 
solution selenium is at once deposited on addition of sulphu- 
rous acid, sulphuric acid being formed, thus : 
H2SeOs + 2SO2 + H2O = 2(H2 S04) 4- Se. 
The metallic selenites correspond closely with the sul- 
phites. 
Selenic Acid, or Di-hydric Selenate. Symbol H2SeC>4 . 
This is best prepared by fusing a selenite with nitre ; on 
addition of a lead salt to the solution of the mass thus ob- 
tained, insoluble lead selenate is precipitated ; this salt is 
decomposed by sulphuretted hydrogen yielding dihydric sele- 
nate and lead sulphide, thus : 
Pb SeCK + H2 S— H2Se04 + PbS. 
On evaporating the liquid obtained, selenic acid is left. 
Selenic acid decomposes on heating into selenic dioxide, 
oxygen, and water ; the metallic selenates correspond to the 
analogous sulphates, and are iso7norphous with them, that is, 
they crystallize in the same forms and have an analogous 
composition. 
Selenmretted Hydrogen, or Di-hydric Selenide. Symbol 
H2Se. Combining Weight 81-5. Density 4075. 
This gas is obtained by the action of an acid upon a 
selenide, exactly as sulphuretted hydrogen is prepared from 
a sulphide. It is a colorless inflammable gas, possessing a 
nauseous smell, and exhibiting properties in every respect 
analogous to those of its sulphur representative. The most 
important difference between the two elements, sulphur and 
selenium, is that the former is oxidized to its highest point by 
the action of nitric acid, whereas the latter requires to be 
fused with nitre in order to reach the corresponding degree 
of oxidation. Elementary Chemistry. 
119 
Tellurium. Symbol Te. Combining Weight 129. 
Density 129. 
Tellurium (from Tellus, the earth) is a very rare substance, 
which, although resembling a metal in its physical properties, 
bears so strong an analogy to sulphur and selenium in its 
chemical relations, that its compounds are best considered in 
this place. It occurs combined with gold and other metals 
in Transylvania and Hungary. The specific gravity of tellu- 
rium is 6-25, and it exhibits a bright white metallic lustre. It 
melts at about 500°, and may be volatilized at a white heat in 
a current of hydrogen gas. When heated in the air it burns 
with a bluish-green flame, forming white fumes of telluric 
dioxide; this compound is also formed when tellurium is 
oxidized by nitric acid, and the solution evaporated to dry- 
ness. With water the dioxide forms tellurous acid, H2 Te03, 
and with metals in place of hydrogen, tellurites of the general 
form, Mj TeOa. When tellurium or a tellurite is fused with 
nitre, potassium tellurate, K2Te04, is formed, from which 
telluric acid, H3 TeO* + 2H30, and the trioxide TeOa can be 
obtained. With hydrogen, tellurium forms a colorless gas, 
H3Te, which cannot be distinguished by its smell from 
sulphuretted hydrogen. 
Oxygen, sulphur, selenium, and tellurium, appear to form a 
natural group of elements, each uniting with two atoms of 
hydrogen to form a series of bodies possessing analogous 
properties, viz. H20, H2S, H2Se, H2Te. The last three 
members of the group exhibit the same kind of striking 
gradation of properties as was noticed in the case of chlorine, 
bromine, and iodine. Thus the mean of the combining 
weights of the two extremes is nearly the combining weight 
of the mean —- -- 8o-5 ; whilst their specific gravities, 
2‘o, 4-5, and 6-25, and their melting and boiling points show a 
similar gradation. 120 
Elementary Chemistry. 
Silicon, next to oxygen, is the most abundant element 
known. It does not occur, however, in the free state, but 
always combined with oxygen to form silicic dioxide (silicic 
acid, or silica). Silicic dioxide exists nearly pure in 
quartz or rock crystal, in flint, sand, and in a variety of 
minerals. Silicon also occurs combined with metals and oxy- 
gen, forming metallic silicates ; and of these the greater 
part of almost all known rocks, especially the primary rocks, 
is composed. 
In order to obtain silicon in the free state, a compound of 
this substance with fluorine and potassium is heated with 
metallic potassium ; a violent reaction occurs, and when the 
contents of the tube in which the decomposition was effected 
are put into water, silicon is left undissolved in the form of a 
brown amorphous powder. Silicon can be obtained in three 
different modifications—amorphous, crystalline, and graphi- 
toidal, corresponding to the modifications of carbon. The 
graphite form of silicon is prepared by heating the brown 
amorphous powder to a high temperature, when the mass 
contracts, and becomes much more dense. Crystalline silicon 
is best obtained by fusing the mixture which gives brown silicon 
with zinc : on cooling the mass, crystals of silicon are found 
to be deposited on the zinc, which latter can easily be re- 
moved by solution in an acid. Silicon thus obtained is hard 
enough to scratch glass ; it has a specific gravity of 2-49, 
and maybe fused at a temperature between the melting points 
of cast iron and steel. 
Silicic Dioxide, or Silica, Symbol Si Oa, Combining Weight 
60, is the only known oxide of silicon ; it occurs in the pure 
state crystallized in six-sided prisms or pyramids, as quartz, 
and exists in a less pure condition in sandstone, chalcedony, 
flint, and agate, &c. The’ aluminium-, potassium-, calcium-, 
and iron-silicates, mixed together in different proportions, 
constitute a large number of minerals. 
Crystallized silica, in the form of white transparent quartz, 
Silicon. Symbol Si. Combining Weight — 28. Elementary Chemistry. 
121 
has a specific gravity of 2-6, and is hard enough to scratch 
glass ; it is unattacked and undissolved by all acids with the 
exception of hydrofluoric acid, by the action of which silicic 
tetrafluoride and water are produced, thus : 
Si02 + 4HF = SiF4 + 2H20. 
Silica is infusible except at the highest temperature of the 
oxyhydrogen blowpipe, when it melts to a colorless globule. 
Silica in an amorphous condition can also be prepared, and 
then exhibits peculiar properties. For this purpose one part 
of finely divided quartz or white sand is heated with four 
parts of sodium carbonate ; as soon as the latter begins to 
fuse, the silica combines with the sodium and oxygen con- 
tained in the carbonate, carbonic acid, C02, being evolved 
with effervescence, owing to the formation of a sodium sili- 
cate. If the fused mass be boiled with water, it will dissolve, 
and on the addition of hydrochloric acid, silicic acid, H4 Si04, 
partly separates as a gelatinous mass, partly remains dis- 
solved in the liquid. If this solution be evaporated to dry- 
ness and heated a little, and hydrochloric acid then added, 
silicic dioxide is left as a white powder insoluble in acids ; 
this amorphous silica possesses a specific gravity of 2-2 to 
2’3, and can only be obtained again in solution by repeating 
the process of fusion with an alkali, &c. A pure aqueous 
solution of hydric silicate can be obtained by allowing the so- 
lution of this substance in hydrochloric acid to dialyse, or 
diffuse through a membrane, for some days. All the hydro- 
chloric acid and soluble chlorides in this solution being crys- 
talloids pass through the dialyser, while the colloidal hydric 
silicate remains behind in solution : the limpid solution thus 
obtained may be concentrated by boiling until the quantity of 
hydric silicate in solution reaches 14 per cent. : but this solu- 
tion is apt to gelatinize on standing, forming a transparent 
jelly-like mass. 
Potassium and sodium silicates are largely used for various 
purposes in the arts, whilst a mixture of these with calcium, 
iron, and lead silicates, forms the several descriptions of 122 
Elementary Chemistry. 
glass (p. ). Some remarkable compounds of silicon with 
oxygen and hydrogen have lately been discovered, but their 
composition has not yet been accurately determined. A com- 
pound of silicon and hydrogen termed Siliciuretted Hydrogen 
is also known : it has, however, not been obtained in the pure 
state ; it is colorless, and takes fire on coming into contact 
with the air, forming silica and water. 
Silicic Tetra-chloride. Symbol SiCb. Combining Weight 
170. Density 85. 
This compound is formed when silicon is heated in chlo- 
rine, but may be prepared by passing dry chlorine over a 
red-hot mixture of finely-divided silica and carbon. Chlo- 
rine alone is not able to decompose silica, but in presence 
of carbon a change is effected, carbonic oxide being at the 
same time formed. 
SiOa + CI« + C2 = SiCU + 2CO. 
Silica, chlorine, and carbon yield silicic tetrachloride and 
carbonic oxide. Fig. 36 shows the arrangement employed 
Fig. 36. 
for preparing this body; the mixture of silica and carbon is 
placed in a porcelain tube, which can be strongly heated by 
the furnace ; dry chlorine gas is passed through the tube, and 
the volatile silicic tetrachloride collects in the cooled tube. 
Silicic tetrachloride is a volatile colorless liquid, boiling at 
59° C, and having a specific gravity of l-52. It is at once Elementary Chemistry. 
123 
decomposed by water, silicic and hydrochloric acids being 
formed ; hence we may see that this body in the chlorine series 
corresponds to silicic dioxide in the oxygen series, and that 
in the formation of the chloride four atoms of chlorine 
simply replace its equivalent quantity, two atoms of oxygen, 
in the silica : SiOa becomes SiCU, as one atom of oxygen is 
equivalent to two of chlorine. 
Silicic Tetra-fiuoride. Symbol SiF4. Combining Weight 
104. Density 52, 
This is one of the most singular compounds of silicon ; it 
is formed whenever free hydrofluoric acid comes in contact 
with either free or combined silica; this is the cause of the 
etching which hydrofluoric acid exerts upon glass. Silicic 
tetrafluoride is best prepared by heating in a flask equal parts 
by weight of finely-powdered fluor spar, and white sand, with 
about eight parts of sulphuric acid: the decomposition first 
occurring is the one by which hydrofluoric acid is generated, 
and this then attacks the silica, thus : 
1) CaF2 + H2S04 = CaS04 + 2HF. 
2) 4HF + SiOa = 2H20 + SiF4. 
Silicic tetrafluoride is a colorless gas which fumes strongly 
in the air ; it does not burn nor support combustion, and may 
be condensed by great pressure, or exposure to a very low 
temperature, to a colorless liquid ; it is decomposed by water, 
but may be collected over mercury, or by displacement; when 
led into water this gas yields hydric silicate, which is depos- 
ited in a state of fine division, and a new acid called hydro- 
fluo-silicic acid, or hydric silico-fluoride, having the composi- 
tion Ha Si Fs, which remains in solution. This substance has 
an acid reaction ; the corresponding potassium- and barium 
silico-fluorides (KaSiF6 and Ba SiF6) are insoluble in water 
and alcohol. 
Boron. Symbol B. Combining Weight wo. 
Boron combined with oxygen and sodium is found as borax 
in nature; it is also found combined with oxygen alone as 124 
Elementary Chemistry. 
boracic trioxide (boracic acid). It exists, like carbon and 
silicon,' in three forms—crystalline, graphitoidal, and amor- 
phous. Boron is easily obtained as a gray amorphous pow- 
der, by heating fused boracic trioxide, B203, with sodium. 
Crystallized boron is prepared by heating the amorphous form 
strongly with aluminium—this metal in the fused state having 
the property of dissolving boron, which separates out in 
nearly colorless crystals when the metal cools, just as the 
graphitoidal form of carbon does from its solution in iron on 
cooling (p. 68). Scales of graphitoidal boron are also formed 
in this way. Crystallized boron has a specific gravity of 2-68, 
and occurs in the form of octahedra, which are hard enough 
to scratch the ruby. In one specimen of these colorless crys- 
tals which were analyzed, some quantity of carbon was found 
to be present; hence carbon may be said to have been pre- 
pared artificially in the diamond modification. Boron burns 
when strongly heated in oxygen or in chlorine, forming the 
oxide or chloride ; it is remarkable as uniting with nitrogen 
by direct combination—in this respect resembling certain 
metals, such as titanium. 
Boracic Trioxide (commonly called Boracic acid). Symbol 
B203. Combining Weight 70-o. 
In certain old volcanic districts in Tuscany constant jets 
of steam and gas escape from the earth. These steam jets, 
which are known as fumerolles or soffioni, contain small 
quantities of boracic acid, HB02 + H20, which collect in the 
lagoons formed at the mouth of the jet. By means of the 
heat of natural steam jets, the solution of boracic acid is 
concentrated, and the acid obtained by crystallization; 
about 2,000 tons of crude acid thus prepared are imported 
every year from Tuscany. Boron likewise occurs in tinkal or 
borax in Thibet, and as boracic trioxide on the coast of Cali- 
fornia. 
Real boracic acid is obtained by decomposing a hot solution 
of borax, Na2 B407, with sulphuric acid; crystals separate 
out on cooling, having the composition H B02 + H20. 
These crystals on heating lose water and pass into a fused Elementary Chemistry. 
125 
glassy mass, consisting of boracic trioxide, B203. Boracic 
acid is slightly soluble in cold, and rather more soluble in hot 
water ; it imparts a peculiar green tint to the blowpipe flame, 
which exhibits a characteristic series of bands when examined 
by means of the spectroscope. Metallic Borates are known, 
and likewise several combinations of these borates with 
boracic trioxide. Thus sodium borate, or boracic acid in 
which the atom of hydrogen is replaced by sodium, is Na B02 
4- 4H2O ; whilst fused borax is this salt combined with one 
molecule of boracic trioxide, thus : 2 Na B02 + B203, or Na2 
B4O7. Compounds similar to this latter salt are known 
amongst the sulphates. Thus Nordhausen sulphuric acid is 
H2S04 + S03, and a sodium compound, Na2 SO* + S03, is 
known. Many of the metallic oxides are soluble in fused 
borax, giving colored glasses. Hence this compound is 
largely used in the arts as a flux, and in the laboratory as a 
blowpipe re-agent. 
Boron combines with chlorine to form a trichloride, BC13, 
and with fluorine to form a corresponding trifluoride, BF3; 
both these compounds are prepared by a method similar to 
that adopted for the corresponding silicon compounds, to 
which, notwithstanding their slightly different constitution, 
they bear a strong resemblance. Like silicon also, boron 
forms a borofluoride : hydrofluoboric acid (or hydric boro- 
fluoride), is HBF4, and potassium borofluoride, KBF4. 
LESSON XV. 
Phosphorus. Symbol P. Combining Weight 31. Vapor 
Density 62.* 
Phosphorus does not occur free in nature, but is found in 
combination with oxygen and calcium in large quantities in 
* The volume occupied by the atom of phosphorus weighing 31 is only half as 
large as that occupied by the atoms of each of the preceding elements: hence the 
atomic volume of phosphorus is i, that of the preceding elements being 1. 126 
Elementary Chemistry. 
the bodies, and especially the bones, of animals, and in the 
seeds of plants. When bones are burnt, a white solid mass 
is left behind; this is called Calcium Phosphate (phosphate 
of lime). Animals obtain the phosphate necessary for the 
formation of their tissues, &c., from plants. Plants, again, 
draw their supply from the soil, whilst soils derive their phos- 
phate from small quantities existing in the oldest granite rocks, 
by the disintegration of which the fertile soils have been pro- 
duced. Phosphorus appears also to be a very necessary 
ingredient in the brain and other centres of the nervous 
action. It was accidentally discovered by Brand of Ham- 
burg in 1669; but Scheele, in 1769, pointed out the existence 
of phosphorus in the bones, and examined its properties care- 
fully. 
Phosphorus is prepared from powdered bone-ash, by mix- 
ing it with two-thirds of its weight of sulphuric acid and 15 to 
20 parts of water. The sulphuric acid decomposes the bone- 
ash, forming calcium sulphate, or gypsum, which separates 
out as a white insoluble powder ; whilst the greater part of 
the phosphorus in the bones comes into solution in combina- 
tion with calcium, oxygen, and hydrogen, forming a salt, com- 
monly known as superphosphate of lime. The liquid is drawn 
off clear, evaporated down to a syrup, and then mixed with 
powdered charcoal, dried, and heated to redness in an earthen- 
ware retort, the neck of which dips under water. The super- 
phosphate may be considered to contain phosphoric pentoxide, 
P2O5, from which the carbon takes away the oxygen, forming 
carbonic oxide, and liberating phosphorus, which distils over 
and condenses under water in yellow drops. 
Phosphorus is an exceedingly inflammable and oxidizable 
substance, and requires great care in its preparation; it is 
manufactured on a very large scale for making the composi- 
tion for the tips of lucifer matches. In order to purify the 
phosphorus thus prepared, it may again be distilled, or pressed 
when melted under hot water through leather ; it is then cast 
into sticks and kept under cold water. Phosphorus is a 
slightly yellow semitransparent solid, resembling white wax Elementary Chemistry. 
127 
both in appearance and consistency; but at low temperature 
it becomes brittle. Its specific gravity is i ‘83, and it melts at 
44% forming a transparent liquid ; it boils at 290°, giving rise 
to a colorless gas. In the air it gives off white fumes, emit- 
ting a pale phosphorescent light in the dark—whence its name 
light, and <ptpu, I bear ; lucifer, from lux, light, and fero, 
I bear, is its literal Latin equivalent); it is then undergoing 
a slow combustion, the white fumes consisting of trioxide. 
At a temperature very little above its fusing point phosphorus 
takes fire in the air, entering into active combustion, and 
forming phosphoric pentoxide, P2O5 (phosphoric anhydride). 
The ignition of phosphorus takes place by slight friction, or 
by a blow, and even the heat of the hand may cause this sub- 
stance to ignite ; hence great care must be taken in handling 
phosphorus, and it should always be cut under water. Phos- 
phorus does not dissolve in water, alcohol, or ether, but it is 
slightly soluble in oils, and very readily soluble in carbonic 
disulphide, crystallizing from its solution in this liquid in 
rhombic dodecahedra. 
If yellow phosphorus be exposed to a temperature of about 
240° for some hours in an atmosphere incapable of acting 
chemically on it (such as hydrogen or carbonic acid), it is 
found to have undergone a very remarkable change, being 
wholly converted into a dark red opaque substance altogether 
insoluble in carbonic disulphide. The weight of red substance 
produced is exactly equal to that of yellow phosphorus used. 
This is called Red, or Amorphous Phosphorus, and differs 
much in its properties from the yellow modification, especially 
in its inflammability, as it does not take fire in the air until 
heated to above 260°, when it becomes reconverted into the 
ordinary form and burns with the formation of phosphoric 
pentoxide. The specific gravity of amorphous phosphorus is 
2T4. The sudden conversion of yellow into red phosphorus 
can be shown by heating a small piece of ordinary phosphorus 
in a dry tube with a mere trace of iodine; combination at 
once occurs, a small trace of volatile phosphoric iodine is 
formed, and the remainder of the phosphorus is converted 128 
Elementary Chemistry. 
into the red modification. The red or amorphous modification 
of phosphorus can also be obtained in a crystallized form by 
heating red phosphorus in a tube with metallic lead. The 
phosphorus dissolves in the melted lead, and on cooling 
separates out in crystals, which possess a bright black metallic 
lustre, and have a specific gravity of 2-34. 
Phosphorus forms two oxides, phosphoric trioxide, P203, 
and phosphoric pentoxide, P206. 
Phosphoric Trioxide, or Phosphorous Anhydride. Sym- 
bol P2O3. Combining Weight no. 
This oxide is formed when phosphorus is burnt in a limited 
current of dry air when it undergoes slow combustion. It 
forms a white non-crystalline powder which combines with 
great energy with water, forming thereby phosphorous acid, 
or hydric phosphite, H3P03. This acid is likewise formed 
when phosphorus is allowed gradually to oxidize in moist air, 
and also by the action of phosphoric trichloride on water, 
thus : 
PC13 + 3H2O = H3P03 + 3HCI. 
Phosphoric trichloride and water give hydricphosphite and 
hydrochloric acid. 
By boiling this solution the hydrochloric acid is driven off, 
and, on cooling, crystals of phosphorous acid are deposited. 
There are two classes of metallic phosphites—the one con- 
tains those which correspond to phosphorous acid in which 
two atoms of hydrogen have been replaced by metal; and the 
second containing those in which one atom only of hydro- 
gen has been thus replaced : the general forms of the two 
will therefore be M2H P03 and MH2 P03, the letter M de- 
noting an atom of a monatomic metal. 
Phosphoric Pe7itoxide (Phosphoric Anhydride). Symbol 
P206. Combining Weight 142. 
This substance is formed when phosphorus burns brightly 
in excess of air or oxygen ; it is a white amorphous light 
powder, which absorbs moisture with the utmost avidity, 
forming hydric phosphate or phosphoric acid, H3 P04 ; it is 
for this reason frequently used in the laboratory for the pur- Elementary Chemistry. 
129 
pose of drying gases. Phosphoric pentoxide is volatile, and 
may be sublimed unchanged by heating in a test tube. It 
can be best prepared by burning small pieces of phosphorus 
placed one by one in a cup hung in the centre of a large dry 
glass globe, and blowing in a sufficient supply of dry air by 
means of a bellows or aspirator. The white powder falls 
down, and may be shaken out of the globe when the operation 
is completed. 
Trihydric Phosphate (Tribasic Phosphoric Acid). Symbol 
H3 PO4. Combining Weight 98. 
When the preceding compound is brought into contact 
with water, great heat is evolved, and combination takes 
place with a hissing noise. If the solution be boiled, trihy- 
dric phosphate is found in solution, being formed thus : 
P206 + 3 H20 = 2(H3 PCX). 
Phosphoric pentoxide and water give trihydric phosphate. 
The corresponding calcium salt, Ca3 2PO4, occurring in 
bone-ash and in many minerals, constitutes the main source 
of all the phosphorus compounds. Trihydric phosphate is 
also formed when phosphorus is heated with nitric acid ; the 
lower oxides of nitrogen are given off as red fumes, and the 
phosphorus gradually disappears ; by evaporating, and boil- 
ing the colorless liquid, trihydric phosphate may be obtained. 
The same substance is procured directly from bone-ash by 
frequent addition of sulphuric acid and continued evapora- 
tion : gypsum gradually separates out, leaving a solution 
from which hydric phosphate can be obtained by neutralizing 
with ammonium carbonate, filtering, evaporating to dryness 
the clear liquid thus obtained, and igniting the residue. If 
sodium carbonate be added to a solution of trihydric phos- 
phate, effervescence will at once ensue from the liberation of 
carbonic acid, and if the carbonate be added until the solu- 
tion ceases to redden litmus paper, a salt will be obtained on 
evaporation which crystallizes in large transparent prisms. 
This is rhombic ox common neutral sodium phosphate j its com- 
position is represented by the symbol Na2H PO4, with twelve Elementary Chemistry. 
atoms of water of crystallization. If caustic soda be added to 
a solution of this common phosphate, a salt termed the sub- 
phosphate crystallizes out in small needles on evaporation : 
the composition of this salt is Na3 P04 with twelve atoms of 
water of crystallization ; and if phosphoric acid be added to a 
solution of common phosphate, the so-called Sodium super- 
phosphate is formed, NaH3P04. We have therefore the 
following tribasic hydric and sodium phosphates ; 
Trihydric Phosphate H3 P04 
Dihydric Sodium Phosphate . . . H2Na P04 
Hydric di-Sodium Phosphate . . . H Na2 P04 
Tri-Sodium Phosphate Na3 P04 
All these substances are distinguished by giving a yellow 
precipitate with solution of silver nitrate consisting of tri-sil- 
ver phosphate, Ag3P04 ; and by producing with ammonia 
and magnesium sulphate a white crystalline precipitate of 
ammonium magnesium phosphate, (NH4) Mg P04. Small 
traces of phosphates can readily be detected by the yellow 
precipitate which forms in nitric acid solution of ammonium 
molybdate. The three atoms of hydrogen in trihydric phos- 
phate may be replaced by three different metals; thus, 
Microcosmic Salt is Hydric-sodium-ammonium Phosphate, 
H Na NH4 P04. 
If common sodium phosphate be heated to redness, water 
is driven off, and a compound called Sodium pyrophosphate 
remains, having the composition Na4 P207, two molecules of 
neutral phosphate yielding one of pyrophosphate, thus : 
2 Na2 H P04 = H20 + Na4 P207. 
When this salt is dissolved in water, it can be recrystal- 
lized, and does not take up water again so as to pass back to 
the state of common phosphate (except on long-continued 
boiling of its solution). This substance gives with silver 
nitrate a white precipitate of silver pyrophosphate, Ag4 P207, 
and thus this class of phosphates may be distinguished from 
130 Elementary Chemistry. 
the preceding or tribasic phosphates. A so-called acid 
sodium pyrophosphate, having the composition Na2H2 P207, 
is also known. 
If microcosmic salt, Na (NH4) H P04, is heated, water and 
ammonia are driven off, and a substance called Sodium 
metaphosphate, Na POs, is left; this dissolves unaltered in 
water, forming one of a third class of phosphates termed 
monobasic phosphates, or metaphosphates. The solutions of 
these salts may be distinguished from those of the two pre- 
ceding classes of salts by their producing gelatinous precipi- 
tates with solutions of calcium and silver salts consisting of 
the metaphosphates of these metals. Monohydric phosphate 
(or metaphosphoric acid), HPO3, is obtaine'd in the form of 
a transparent icelike mass by evaporating the solution of 
trihydric phosphate and igniting the residue. Oh dissolving 
this glacial acid in cold water, a solution of monohydric phos- 
phate is obtained, but this, on boiling, changes to the tri- 
hydric phosphate. 
From the above it is seen that three modifications of phos- 
phoric acid are known, or rather, three different acids, each 
giving rise to a class of metallic salts. Thus we have— 
(1) Tri-hydric phosphate, or phosphoric acid, H3 P04, and 
tri-sodium phosphate, Na3 P04. 
(2) Tetra-hydric pyrophosphate, or pyrophosphoric acid, 
H4P207, and sodium pyrophosphate, Na4 P207. 
(3) Mono-hydric phosphate, or metaphosphoric acid, HPOs, 
and sodium metaphosphate, NaPOs. 
Each of the above hydric phosphates can be prepared by 
passing sulphuretted hydrogen through water containing in 
suspension the corresponding silver salts ; thus : 
(1) 2(Ag3P04) + 3(H2S) = 2(H3 P04) + 3(Ag2 S). 
(2) Ag4P207 + 2(H2S) = H4 P207 + 2(Ag2 S). 
(3) 2(Ag PO3) + (H2S) = 2(HP03) + Ag2S 
In addition to the phosphates and phosphites, a class of 
salts termed Hypophosphites is also known : the composition 
of hydric hypophosphite is represented by the formula 132 
Elementary Chemistry. 
H PH202, and that of sodium hypophosphite by NaPH202 ; 
and these salts may be supposed to be hydric or sodium me- 
taphosphate, HPOa, and NaP03, in which one atom of oxy- 
gen has been replaced by its equivalent, or two atoms of hy- 
drogen. Sodium hypophosphite is obtained by acting with 
caustic soda on phosphorus, when phosphuretted hydrogen 
gas is evolved, and a solution of hypophosphite remains 
behind. 
Phosphorus and Hydrogen. Three compounds of phos- 
phorus and hydrogen are known—PH3, a gas ; PH2 (or 
P2H4), a liquid ; and P2H (or P4 H2), a solid substance. 
Phosphuretted Hydrogen. Symbol PH3. Combining 
Weight 34. Density 17. 
This gas is obtained in the pure by the decomposition 
of hydric phosphite, or hydric hypophosphite, but it is gen- 
erally prepared by the action of caustic potash on phos- 
phorus. 
3 KHO + P4 + 3H2Q = 3 KPH202 + PH3. 
Caustic potash, and phosphorus, and water, give potassium 
hypophosphite and phosphuretted hydrogen. 
Each bubble of the gas thus prepared takes fire spon- 
taneously on coming into contact with the air, forming sin- 
gular rings of phosphoric pentoxide, which expand as they 
rise. This self-inflammability of the gas depends upon the 
presence of small quantities of the liquid hydride P.2H4, which 
may be condensed to a volatile and very inflammable liquid 
by passing the gaseous hydride through a tube cooled by a 
freezing mixture. Pure phosphuretted hydrogen prepared 
from hydric phosphite by heat, does not undergo spontaneous 
combustion in the air. This mode of formation may be thus 
represented : 
4(H3 P03) = 3(H3 P04) + PH3. 
Hydric phosphite gives trihydric phosphate and phos- 
phuretted hydrogen. 
There is some doubt about the exact formulas of the other 
two hydrides: the formulas P2H4 and P4H2, are in accordance Elementary Chemistry. 
133 
with their physical states, and are, on certain other theoret- 
ical grounds, to be preferred to PH2 and P2H. 
Phosphorus and Chloride. Two chlorides of phosphorus 
are known—Phosphoric trichloride, PC13 and Phosphoric 
pentachloride, PC15. The first of these is a colorless strong- 
ly fuming liquid, which is easily formed by passing a current 
of chlorine gas over phosphorus contained in a retort : when 
thrown into water it sinks down as a heavy oil, but is gradually 
decomposed, hydric phosphite and hydrochloric acid being 
formed (see p. 128), The specific gravity of the trichloride is 
1-45, and its boiling point is 73°'8. Phosphoric trichloride 
rapidly absorbs chlorine gas, and is converted into the penta- 
chloride, a yellowish solid substance, which is also formed 
when phosphorus is burnt in an excess of chlorine. Phos- 
phoric pentachloride is decomposed in presence of excess of 
water, forming trihydric phosphate and hydrochloric acid ; 
but when only a limited quantity of water is present, a liquid 
termed phosphoric oxichloride is formed, having the composi- 
tion PCbO, and boiling at no°. Corresponding compounds 
with bromine are likewise known. With sulphur, phosphorus 
forms several compounds, and it is an interesting fact that 
two of these, compounds, P2S3 and P2Sb, correspond in com- 
position with the oxides P203 and PnOs. The oxide cor- 
responding to P2S, however, is as yet unknown. 
LESSON XVI. 
Arsenic. Symbol As. Combining Weight 75. Density of 
Vapor 150.* 
Arsenic closely resembles phosphorus in its chemical prop- 
erties and in those of its compounds, although in physical 
* The volume occupied by an atom of (gaseous) arsenic weighing 75 is only half 
of that occupied by the other elements generally; in this respect arsenic re- 
sembles phosphorus. Elementary Chemistry. 
134 
characters, such as specific gravity, lustre, &c., it bears a 
greater analogy to the metals : indeed, it may be considered 
the connecting link between these two divisions of the ele- 
ments, antimony and bismuth being closely connected with it 
on the one hand, and phosphorus and nitrogen on the other. 
Arsenic is sometimes found in the free state, but more fre- 
quently combined, chiefly with iron, nickel, cobalt, and sul- 
phur. It is also contained in very small quantities in many 
mineral springs. In order to separate arsenic from any of the 
metallic ores in which it occurs, the ore is roasted, or exposed 
to a current of heated air in a reverberatory furnace ; the ar- 
senic combines with the atmospheric oxygen, forming arsenic 
trioxide or arsenious oxide, AS2O3, which is carried in the 
state of vapor from the furnace into long chambers or flues in 
which the trioxide (commonly known as arsenious acid, or 
white arsenic) is deposited. Metallic arsenic may be prepared 
from this oxide by mixing it with charcoal and sodium carbon- 
ate, and heating in a closed crucible, the upper part of which 
is kept cool : arsenic condenses in the cool part of this ap- 
paratus as a solid with a brilliant grayish lustre. It tarnishes 
in the air from oxidation; it has a specific gravity of 57 to 
5’9, and when heated to dull redness, it volatilizes as a color- 
less vapor without undergoing fusion, and this vapor pos- 
sesses a remarkable garlic-like smell. Arsenic when heated 
in the air takes fire, and burns with a bluish flame, forming 
arsenious oxide, As2 03 ; when thrown into chlorine it in- 
stantly takes fire, forming arsenic trichloride, AsCb. 
Oxides of Arsenic. Two compounds of arsenic and oxy- 
gen are known. (1) Arsenic Trioxide or Arsenious Oxide, 
As203 (arsenious acid or white arsenic). (2) Arsenic Pent- 
oxide or Arsenic Oxide, AS2O6 (arsenic anhydride). 
Arsenious Trioxide. Symbol As2Os. Combining Weight 
198. Density (of vapor) 198. 
This substance is formed when arsenic is burnt in the air 
or in oxygen, but it is generally prepared by roasting arsen- 
ical pyrites, FeSAs ; its specific gravity is 36. It exists in 
two distinct forms, the crystalline and the vitreous ; it occurs Elementary Chemistry. 
135 
in the first modification crystallized in brilliant octahedra, and 
in the second as a semi-transparent glass-like solid, devoid of 
crystalline structure : this form of the substance, on standing, 
becomes opaque like porcelain, diminishing in specific gravity. 
Arsenious oxide is feebly soluble in water; the solution 
(which may be considered to contain true arsenious acid or 
trihydric arsenic, H3As03, analogous to phosphorous acid) has 
a feebly acid reaction : it dissolves more readily in hydro- 
chloric acid, and is freely soluble in solutions of the alkalies, 
arsenites being formed of the general form M3As03 ; thus, 
trisilver arsenite is Ag3AsOa. The alkaline arsenites are 
soluble in water ; those of the metals of the alkaline earths 
and heavy metals are insoluble in water. Sodium arsenite is 
used largely in calico printing ; Scheele’s green and Emerald 
green are compounds containing arsenious trioxide and 
copper, both of which are made in large quantities for em- 
ployment as a pigment. All the soluble arsenites are dread- 
fully poisonous ; the best antidote is freshly prepared ferric 
hydrate (hydrated ferric oxide), or magnesia, which form inso- 
luble arsenites, and thus prevent the poison from entering 
into the system. When heated to about 220° C, arsenious 
oxide volatilizes without melting, forming an inodorous and 
colorless vapor. It is occasionally met with crystallized in 
long needles of the same form as the crystals of the corre- 
sponding oxide in the antimony series (see p. 200). 
Arsenic Pentoxide or Arsenic Oxide (arsenic anhydride). 
Symbol As2 05. Combining Weight 230. 
This oxide is obtained by acting upon the trioxide with 
nitric acid, evaporating to dryness, and heating to a tempera- 
ture of 270°. It forms a non-crystalline white powder, which, 
when strongly heated, decomposes into As2Os and 02. This 
powder is readily dissolved by water, and the solution yields 
crystals of arsenic acid, or trihydric arsenate, H3As04: the 
metallic compounds corresponding to this are called arsen- 
ates, and resemble the corresponding tribasic phosphates 
(p. 130) in composition, whilst they are identical with them in 
crystalline form. Thus we have, 136 
Elementary Chemistry. 
Tri-Sodium Arsenate . . Na3As04 + H20. 
Hydric Di-Sodium Arsenate HNa2As04 +12 H20. 
Di-hydric Sodium Arsenate . H2NaAs04 + H20. 
Tri-hydric Arsenate . . . H3ASO4. 
With solutions of magnesium and ammonium together, solu- 
ble arsenates, like phosphates, form an insoluble precipitate, 
having the composition NH4 Mg As04 + 6H20 (ammonium 
magnesium arsenate). The arsenates of the alkaline metals 
are soluble, those of the other metals insoluble in water. 
Trisilver arsenate is a characteristic salt of a brownish-red 
color, whereas trisilver arsen/te has a bright yellow tint. 
Arsenic acid acts as a still more powerful poison than 
arsenious acid. 
No arsenates corresponding to the pyro- and metaphos- 
phates have been, as yet, obtained ; compounds having 
the composition H4 As2 07, and H AsOa have been indeed 
prepared by heating a tribasic salt; but on solution in water 
they combine again with it and present only the characteris- 
tics of the tribasic acid. 
Arsenic and Hydrogen. Arseniuretted Hydrogen. Sym- 
bol AsH3. Combining Weight 78. Density 39. 
This compound, which corresponds to phosphuretted hy- 
drogen, and to ammonia, is formed by decomposing an alloy 
of arsenic and zinc with sulphuric acid. It is a colorless gas, 
possessing a fetid odor of garlic, and acts as a most deadly 
poison, a single bubble of the pure gas having been known 
to act fatally : when cooled to - 40° it condenses to a color- 
less liquid. Arseniuretted hydrogen burns with a bluish 
flame and deposits arsenic upon a cold body held in the 
flame : below a red heat it is decomposed into arsenic and 
hydrogen. 
Arsenic unites with chlorine, bromine, and iodine, to form 
arsenic trichloride, tribromide, and triiodide. The trichloride 
is a colorless volatile liquid, boiling at 132% which decom- 
poses in contact with water, yielding arsenious and hydro- 
chloric acids. Three sulphides of arsenic are known— Elementary Chemistry. 
137 
Arsenic Disulphide, As2S2, which occurs naturally as Real- 
gar ; Trisulphide, As2S3, also occurring in nature as Orpi- 
ment; and Pentasulphide, AS2S5. Orpiment may be 
obtained by passing a stream of sulphuretted hydrogen gas 
through the acid solution of the corresponding oxide, when 
it is precipitated as a yellow powder. The arsenic sulphides 
form with the sulphides of the alkaline metals compounds 
bearing the same analogy to the trisulphide and pentasul- 
phide that arsenites and arsenates do to the trioxide and 
pentoxide : in short, these compounds are sulphur and salts, 
the arsenites and arsenates being oxysalts ; hence they are 
called and sulpharsenates. 
Arsenic possesses characters of so peculiar a kind, that its 
presence even in very minute traces can be detected with 
certainty. From its solutions it can be precipitated as sul- 
phide, by the aid of sulphuretted hydrogen : and this sulphide, 
when dried and fused in a small test tube with a mixture of 
potassium cyanide and sodium carbonate, yields a ring of 
metallic arsenic : on heating, the metal is oxidized to the tri- 
oxide, which deposits in minute octahedral crystals. These, 
when boiled with water, yield a solution giving a bright green 
precipitate with neutral copper solutions, and a bright yellow 
one with neutral silver salts. Arsenic in solution may be also 
detected by the evolution of arseniuretted hydrogen, on 
adding zinc and sulphuric acid to the solution to be tested: 
on burning the gas, arsenic is deposited in the metallic state 
upon a piece of cold porcelain held in the flame. This mirror 
dissolves in solution of sodium hypochlorite ; and if treated 
with nitric acid, and the solution neutralized, yields with sil- 
ver nitrate solution a red precipitate of trisilver arsenate. 
Many compounds of arsenic heated on charcoal in the inner 
blowpipe flame give a garlic odor of arsenic. Solutions con- 
taining arsenic boiled with hydrochloric acid and clean cop- 
per, deposit a coating of arsenic upon the copper: this coat- 
ing, on drying and heating in a test tube, gives a ring or 
mirror of arsenic, which may be oxidized to trioxide and 
tested as before. By these, and other reactions, the pres- Elementary Chemistry. 
ence of the minutest portion of arsenic may be detected with 
certainty. 
The general chemical analogy between nitrogen, phos- 
phorus, and arsenic, is well seen when their corresponding 
compounds are examined ; thus the hydrides, oxides, and 
chlorides, have an analogous composition. 
N2Os N3Ob NH3 NC13 (?) 
P203 P206 PH3 PC13 
As203 As2Ob AsH3 AsC13 
These three elements are all Triatomic, that is, one atom 
of each of these bodies is equivalent to, and capable of, re- 
placing three atoms of hydrogen. Antimony and bismuth 
(see pp. 199, 201) exhibit in their chemical relations a striking 
resemblance to the foregoing group. 
At07nicity of the Elements. 
If we compare together the compounds of the preceding 
elements with hydrogen, we find that the molecule of 
certain of these compounds contains one atom of hydrogen ; 
that is to say, the combining weight (or two volumes) of the 
compound contains the combining weight (or one volume) of 
hydrogen ; whilst the molecule of others contains two atoms 
of hydrogen ; that is, two volumes of the compound contains 
two volumes of hydrogen : in others, the molecule contains 
three or four atoms of hydrogen, united in each case to one 
atom of some other element. Thus one atom, or one volume 
of chlorine, bromine, iodine, or fluorine, combines with one 
atom or one volume of hydrogen to form one molecule, or two 
volumes of the several hydracids, hydrochloric, and hydro- 
bromic, &c. : whilst one volume of oxygen, sulphur, and 
selenium, on the other hand, unites with two volumes of 
hydrogen to form two volumes or one molecule of water gas, 
or sulphuretted hydrogen. One volume of nitrogen (or four- 
teen parts by weight), and half a volume of arsenic and phos- 
phorus (or, respectively, seventy-five and thirty-one parts by 
weight) unite, on the other hand, with three volumes of hydro- Elementary Chemistry. 
139 
gen (or three parts by weight) to form two volumes or one 
molecule of ammonia, phosphuretted and arseniuretted hydro- 
gen ; whilst twelve parts by weight of carbon unite with four 
volumes of hydrogen, to form the molecule of the typical 
compound, marsh gas. 
Hence we come to distinguish the elements into groups, 
according to fheir power of combining with, or replacing, dif- 
ferent quantities of hydrogen : thus we call chlorine, bromine, 
iodine, and fluorine, monatomic elements, or monads; oxy- 
gen, sulphur, selenium (and tellurium), diatomic elements, or 
dyadsj nitrogen, phosphorus, arsenic (antimony, bismuth, 
and boron), triatomic elements, or triads; carbon (and 
(silicon), tetratomic elements, or tetrads. The class of 
monads possess only one combining power, or atomicity, 
while the dyads possess two, the triads three, and the tetrads 
four such combining powers. In like manner the metallic 
elements can be divided into classes according to their 
atomicities, their power of combining with chlorine and other 
monads being regarded as the measure of their atomicity, 
few compounds of metals with hydrogen being known. 
Not only can the elements thus be considered as possess- 
ing varying atomicity, but also those groups of elementary 
atoms, which act collectively as elements, and to which the 
name of compound radicals is given. Thus, nitric acid may, 
as we have seen, be considered as water, in which one atom 
of hydrogen is replaced by the 7no7iad radical, N02 ; thus, 
H 7 H ) 
water O, nitric acid, O, Nitric pentoxide is again 
nitric acid with the second atom of hydrogen replaced by the 
same radical | O = N206. Sulphuric acid, on the other 
hand, may be considered as built up on the type of two mole- 
cules of water, in which two atoms of hydrogen are replaced 
by the dyad radical S02. 
H 'J 
Water i 02. Sulphuric Acid 11 > 02 
Hs* S02 140 
Elementary Chemistry. 
Again, phosphoric acid may be regarded as three molecules 
of water, in which three atoms of hydrogen have been replaced 
by the triad radical PO ; thus— 
III 
§:}o. 
The atomicity of an element, or of a compound radical, 
may be conveniently expressed by placing the Roman nume- 
rals above the symbol for those which are not monads, thus : 
II III IV II III 
H, O, N, C, N02, S02, PO, &c. 
LESSON XVII. 
The Metallic Elements, 
The metals are much more numerous than the non-metallic 
elements ; there are fifty of the former, and only fourteen of 
the latter: very many metals are, however, found in small 
quantities, and the properties of these and their compounds 
are but little known, so that in this work we shall only con- 
sider the most important and commonly occurring metals. 
It has already been stated that the division of the elements 
into these two classes is one of convenience only, and is not 
founded on any essential difference ; thus arsenic and anti- 
mony may, in some respects, be considered as metals, and in 
others as non-metals. 
All metals, with the single exception of mercury (a liquid), 
are solid at the ordinary temperature ; they possess a high 
power of reflecting light, causing the bright, glittering appear- 
ance known as the metallic lustre; they are better conductors 
of heat and electricity than the non-metals, and, as a rule, 
they have a higher specific gravity than these. The metals Elementary Chemistry. 
141 
differ widely from each other, both in their physical and 
chemical properties, and are, accordingly, adapted for different 
uses ; those metals which are lightest exhibit the greatest 
power of union with oxygen, whilst the heavier metals undergo 
oxidation with difficulty. 
Physical Properties of the Metals. 
Specific Gravity. — The following table, giving the specific 
gravities of the most important metals (water at o° C. = I'oo), 
shows the great variation which they exhibit in this respect: 
Table of Specific Gravities. 
Iridium 2i-8 
Platinum . . . . 21*5 
Gold 19-3 
Mercury 13 596 
Thallium . . . . 11*9 
Palladium . , . . 11 -8 
Lead 11-3 
Silver 10-5 
Bismuth 9-8 
Copper 8-9 
Nickel 8-8 
Cadmium .... 8-6 
Cobalt 8-5 
Manganese .... 8-o 
Iron y 8 
Tin . 7-3 
Zinc 7-i 
Antimony 67 
Arsenic 5*9 
Chromium . ... 5-9 
Aluminium .... 2-56 
Strontium 2-54 
Magnesium .... 175 
Calcium 1-58 
Rubidium 1-52 
Sodium 0-972 
Potassium 0-865 
Lithium °'S93 
Fusibility.—The melting points of the metals differ even 
more widely than their densities, mercury fusing at 40° be- 
low zero, and platinum only melting at the highest tempera- 
ture of the oxyhydrogen blowpipe. 
Table of Melting Points. 
Mercury — 40° 
Tin + 235° 
Bismuth 270° 
Cadmium 315° 142 
Elementary Chemistry. 
Lead 3340 
Zinc 423° 
Antimony ...... 425° 
Silver . . . . • 1,000° 
Copper 1,090° 
White Cast Iron . 1,050° 
Gray ditto . 1,200° 
Steel. . . 1,300° to 1,400° 
Wrought Iron 1,500° to 1,600° 
Some of the metals can be easily converted into vapor, or 
volatilized ; thus mercury boils at 350°, arsenic passes into 
vapor even before it assumes the liquid form, whilst potas- 
sium, sodium, magnesium, zinc, and cadmium, can be dis- 
tilled at a red heat. Even the more infusible of the metals, 
such as copper and gold, are not absolutely fixed, but gige 
off small quantities of vapor when strongly heated in a 
furnace. 
The color of most of the metals is nearly uniform, varying 
from the bright white of silver to the bluish-gray of lead ; 
copper is the only red-colored metal known, whilst gold, 
strontium, and calcium are yellow. In ductility, or the 
power of being drawn out into wire, and malleability, or the 
power of being hammered out into thin sheets, the metals 
differ considerably. Gold is the most malleable of all the 
metals, being capable of being beaten out to the thickness of 
the rinfffonth part of an inch ; it is, likewise, the most ductile 
metal. Hardness, brittleness, and tenacity, are physical 
properties of great importance, in which the metals differ 
widely. 
Occurrence and Distribution of the Metals. 
Only a few of the metals occur in the free or uncombined 
state in nature ; in general they are found combined with 
oxygen, sulphur, or some other metalloid. These metallic 
compounds exist most variously distributed throughout the 
earth’s crust; some are known to occur in only one or two 
localities, and even then only in minute quantity, whereas 
others are found widely distributed in enormous masses. As 
is seen by reference to the table on p. 8, the metals alumi- 
nium, iron, calcium, magnesium, and sodium occur in very large Elementary Chemistry. 
143 
quantities, forming, when united with oxygen and silicon, the 
whole mass of granitic rocks composing our globe ; but it is 
not from these sources that the metals in question can be ob- 
tained for the purposes of the arts. For this object, we 
employ other combinations, found in smaller quantity, from 
which the metals can be more easily extracted than from the 
silicates, and these compounds are termed the metallic ores. 
The heavy metals and their ores generally occur inter- 
spersed throughout the old granitic or early sedimentary rocks 
in the form of veins or lodes, which are cracks, or fissures, 
running through the rock in a particular direction, and filled 
up with a metallic ore. Other ores, such as ironstone, are 
found amongst the more recent sedimentary formations, 
having been deposited in large masses, probably from aque- 
ous solution. 
The consideration of the occurrence and distribution of the 
various metallic ores belongs to the science of geology ; the 
study of the modes of procuring the ores is the province of 
the miner and engineer ; whilst the processes by means of 
which the metal itself is obtained from the ore, although main- 
ly dependent upon chemical principles, are generally classed 
as belonging to the branch-science of metallurgy. 
Classification of the Metals. 
The metals can be conveniently grouped into classes, in 
which the several members possess certain properties and 
general characters in common. 
Class I. Metals of the Alkalies.—I, Potassium. 2, So- 
dium. 3, Caesium. 4, Rubidium. 5, Lithium. (6, Ammo- 
nium.) 
General Characteristics.—The metals of this class are 
monatomic ; that is, the atom of metal replaces one atom of 
hydrogen ; they are soft, easily fusible, volatile at higher 
temperatures ; they combine with great force with oxygen, 
decompose water at all temperatures, and form basic oxides, 
which are very soluble in water, yielding powerfully caustic 144 
Elementary Chemistry. 
and alkaline bodies, from which water cannot be expelled by 
heat. Their carbonates are soluble in water, and each metal 
forms only one chloride. Ammonium, NHi. is added to the 
list of alkaline metals proper, from the general similarity of 
the ammoniacal salts to those of potash and soda. 
These metals and their compounds are closely analogous in 
their properties, and they exhibit a remarkable relation as re- 
gards their atomic weights ; thus, sodium, which stands 
between potassium and lithium in properties, has a com- 
bining weight, which is the arithmetic mean of the other two, 
— 23 ; so, too, rubidium, standing half-way between 
cjesium and potassium, has a mean atomic weight, 1 r3 + 39 — 
2 
86. 
Class II. Metals of the Alkaline Earths.—1, Calcium. 
2, Strontium. 3, Barium. 
General Characteristics.—The metals of this class are dia- 
tomic ; that is, the atom replaces two atoms of hydrogen ; the 
metals cannot be reduced by hydrogen or carbon alone, they 
decompose water at all temperatures, producing oxides, which 
combine with water to form hydrates, from some of which the 
water can be driven off by heat. Their carbonates are inso- 
luble in water, but soluble in water containing carbonic acid 
in solution. 
Class III. Metals of the Earths.—1, Aluminium. 2, 
Glucinium. 3, Zirconium. 4, Thorium. 5, Yttrium. 6, 
Erbium. 7, Cerium. 8, Lanthanum. 9, Didymium. 
With the exception of aluminium, these metals are hardly 
known in the free state, as their compounds occur so rarely 
that they are not employed for any useful purpose, and their 
properties cannot be considered in an elementary work. The 
oxides of this group are insoluble in water ; and they cannot 
be reduced to the metallic state by hydrogen or carbon. 
Aluminium is tetratomic, one atom replacing four atoms of 
hydrogen. 
Class IV. Zinc Class.—1, Magnesium. 2, Zinc. 3, Elementary Chemistry. 
145 
Cadmium. These metals are diatomic ; they are all volatile 
at high temperatures, and burn when heated in the air: they 
decompose water at a high temperature, or in presence of an 
acid, and form only one oxide and one chloride. 
Class V. Iron Class.—I, Manganese. 2, Iron. 3, Co- 
balt. 4, Nickel. 5, Chromium. 6, Uranium. 7, Indium. 
These are diatomic, and equivalent to two atoms of hydro- 
gen ; they are not volatile at the temperature of our fur- 
naces ; they decompose water like the preceding class, and 
they form several oxides, chlorides, and sulphides. 
Class VI. Tin Class.—1, Tin. 2, Titanium. 3, Niobium. 
4, Tantalum. Tin is the only one of this class employed in 
the arts. These metals decompose water at high temperatures 
and in presence of alkalies ; they form dioxides and volatile 
tetrachlorides, and are hence tetratomic. 
Class VII. Tungsten Class.—1, Molybdenum. 2, Vana- 
dium. 3, Tungsten. These metals are all of rare occurrence ; 
they decompose water at a high temperature, and form tri- 
oxides and volatile hexachlorides. 
Class VIII. Arsenic Class.—1, Arsenic. 2, Antimony. 
3, Bismuth. The metals of this class are triatomic, they form 
the junction between the metals and metalloids, and they 
closely resemble phosphorus in their properties. 
Class IX. Lead Class.— 1, Lead. 2, Thallium: heavy 
metals, allied in their general properties to the two first classes. 
Lead is diatomic, but thallium is monatomic. 
Class X. Silver Class.—x, Copper. 2, Mercury. 3, Silver. 
These metals do not decompose water under any circum- 
stances ; they are oxidized by nitric and strong sulphuric 
acids; copper and mercury form two basic oxides which, 
except in the case of copper, are decomposed by heat alone. 
Copper and mercury are diatomic ; silver is monatomic. 
Class XI. Gold class.—1, Gold. 2, Platinum. 3, Palla- 
dium. 4, Rhodium. 5, Ruthenium. 6, Iridium. 7, Osmium. 
These metals are not acted upon by nitric acid, but only by 
chlorine or aqua regia, and the oxides are reduced by heat 
alone ; and they with silver and mercury constitute the noble 146 
Elementary Chemistry. 
metals. Gold is triatomic, and the other members of this 
class are tetratomic. 
Chemical Properties of the Metals. 
The metals combine (i) with each other to form alloys ; (2) 
with the metalloids to form oxides, sulphides, chlorides, &c. 
In the alloys the metallic appearance and properties are pre- 
served, whereas in the compounds with the metalloids the 
physical properties of the metals as a rule disappear. 
Alloys. The compounds formed by the metals amongst 
themselves are not so stable as those which are formed by 
union with a metalloid ; nevertheless the alloys are largely used 
in the arts, as they possess many valuable properties not 
exhibited by the metals separately. Thus gold and silver are 
too soft to be used alone as a medium of currency, but the 
addition of 7 5 per cent, of copper gives an alloy of the requi- 
site hardness ; then copper is too soft and tough to be wrought 
in the lathe, but when alloyed with half its weight of zinc it 
forms a hard and most useful substance known as brass. 
Gun-metal, or bronze, is a hard and tenacious alloy of 90 parts 
of copper and 10 of tin. Bell-metal, a still harder alloy, 
contains the same metals in the proportion of 80 of the former 
to 20 of the latter, whilst an alloy of 33 parts of tin to 67 of 
copper possesses a white color, takes a high polish, and is 
known as speculum-metal, and employed for the reflectors of 
telescopes. For making printing type a peculiar alloy is 
employed, containing 80 parts of lead to 20 of antimony ; this 
possesses many properties necessary for type metals, which 
are found to belong to no single metal or other alloy. 
The chemical composition of the alloys is not so definite or 
so well marked as that of the other metallic compounds, but 
they may frequently be obtained in crystals in which the con- 
stituents are contained in atomic proportions, The melting 
point of an alloy is often much lower than the melting points 
of its constituent metals. Thus lead melts at 334°, bismuth Elementary Chemistry. 
at 270°, tin at 235% and cadmium at 315°; whereas an alloy 
of 2 parts bismuth, 1 of tin, and 1 of lead, melts at 95° to 
98° C, and one containing 8 of lead, 15 bismuth, 4 of tin, and 
3 of cadmium, softens at as low a temperature as 6o°, and is 
perfectly fluid at 65° C. The alloys of metals with mercury 
are termed Amalgams. 
Coinpounds of the Metals with Metalloids. 
1. Metallic Oxides. Oxygen acts very differently on the 
different metals. Some metals, such as zinc, magnesium, and 
calcium take fire when heated, and burn with the evolution 
of intense light ; whilst others, such as gold and silver, do 
not combine directly with oxygen, and are only obtained in 
combination with it by indirect means and with difficulty. 
The oxides differ widely in properties and composition ; 
they may, however, all be represented as water in which the 
hydrogen has been replaced by metal. Thus the monoxides 
may be considered to be water in which either each atom of 
hydrogen is replaced by a monad, as K20, Ag20, or the two 
atoms of hydrogen are replaced by a dyad, as Ba O, Zn O ; 
whilst the higher oxides are regarded as two or more mo- 
lecules of water, in which the hydrogen is in like manner 
replaced by its equivalent of metal. The most important of 
these higher oxides are the sesquioxides, such as alumina, 
AU 03, and ferric oxide, Fe203; the dioxides, such as black 
oxide of manganese, MnOa; the trioxides, as chromium tri- 
oxide, Cr 03. 
2. Metallic Sulphides. Metals combine directly with sul- 
phur to form sulphides, and these occur frequently in nature, 
forming many of the metallic ores. These compounds re- 
semble in composition the corresponding oxides, and may be 
represented as sulphuretted hydrogen, H2S, in which the 
hydrogen is replaced by its equivalent of metal. The sul- 
phides of the first and second class of metals are soluble in 
water; those of the remaining almost all insoluble in water, 148 
Elementary Chemistry. 
but some of them soluble, and others insoluble, in acids and 
alkalies. In the laboratory this difference in the solubility 
of the sulphides is employed as a means of separating the 
different metals in the processes of chemical analysis. 
3. Metallic Chlorides. The metals unite directly with chlo- 
rine to form an important class of compounds, which may 
be considered as one or more molecules of hydrochloric 
acid, in which the hydrogen is replaced by its equivalent of 
metal; thus K Cl is the chloride of a monad ; Ba Cl3 that of 
a dyad, and this may be considered as two molecules of hydro- 
chloric acid, in which two atoms of hydrogen are replaced by 
the dyad barium ; whereas antimony trichloride, SbCls, may 
be represented as three molecules of hydrochloric acid, in 
which the three atoms of hydrogen are replaced by one atom 
of triatomic antimony. 
4. Metals unite with bromine, iodine, fluorine, and cyanogen 
to form bromides, iodides, fluorides, and cyanides, all of which 
bear a strong resemblance to the corresponding chlorides, 
and may be considered to possess an analogous constitution. 
5. Metals also unite with nitrogen, phosphorus, boron, 
silicon, carbon, and hydrogen ; but the compounds thus formed 
are in general of slight importance. 
6. Metallic Salts.—The replacement of the hydrogen in 
acids (the hydrogen salt), by its equivalent of metal, gives rise 
to the formation of a very large class of bodies to which the 
name of metallic salts has been given; thus, if we replace 
both atoms of hydrogen in hydric sulphate, H3 S04, by 
potassium, we get potassium-sulphate, K„ S04; if only one 
is replaced, we have hydric-potassium sulphate, KH S04; if we 
replace both the atoms of hydrogen with a dyad, we have 
Ba S04, or Zn S04. The same holds good for all the other 
acids ; thus, H3 P04 (trihydric phosphate) yields Ag3 P04 
(trisilver phosphate); H NQ3 yields K N03, or Ba N2 06. 
The metals forming sesquioxides also give rise to salts which 
may be considered as being composed of several molecules 
of the acid with the hydrogen replaced by the metal; thus 
aluminium sulphate is three molecules of hydric sulphate. Elementary Chemistry. 
149 
3 (H2 S04), in which the 6 of hydrogen are replaced by 2 atoms 
of aluminium ; thus, Ala 3 S04. The constitution of the other 
classes of salts will be best understood from the special 
descriptions. Many of the metallic salts when crystallized 
contain a definite number of atoms of water, and this is termed 
water of crystallization. 
LESSON XVIII. 
Most chemical substances, when they pass from the liquid 
or gaseous into the solid state, assume some definite geome- 
tric form, or are said to crystallize. Crystals are produced 
when a substance, such as nitre, is dissolved in water and 
the solution allowed gradually to evaporate ; or when a body, 
such as sulphur, is melted and allowed to solidify by cooling ; 
or when a volatile substance, such as iodine or arsenious 
oxide, is vaporized and the vapor condensed on a cool surface. 
Many naturally occurring minerals exhibit very perfect crys- 
talline forms ; we are ignorant of the mode in which such 
crystals are in most cases produced, but we know that the 
process of their formation has been a very slow one, and we 
find that, in general, a crystal is larger and more perfect the 
more gradually it has been formed. Crystalline bodies exhibit, 
in addition to their regular form, a peculiar power of splitting 
in certain directions more readily than in others, called cleav- 
age; as well as in many cases the property of allowing the 
rays of light and heat to pass more readily in one direction 
than another, giving rise to the well-known phenomena of 
double refraction. 
Inorganic bodies which do not exhibit these peculiarities, or 
assume crystalline structure, are said to be amorphous j but 
certain highly complicated structures found in the vegetable 
Crystallography. 150 
Elementary Chemistry. 
and animal world exhibit a structure which, although it is 
non-crystalline, is not devoid of arrangement, and to which 
the name organized or celhilar structure has been given. 
As a rule, every particular substance possesses a definite 
form in which it always crystallizes, and by which it can be 
distinguished; when a crystal is formed, from aqueous solu- 
tion, for example, the smallest visible particle possesses the 
complete form of the largest crystal, and simply increases in 
size without undergoing any change of form. 
It has been found possible to arrange the many thousand 
different known crystals in six systems, to each of which 
belongs a number of forms having some property in common. 
In order to classify these different crystals, the existence of 
certain lines within the crystal called axes is supposed, round 
which the form can be symmetrically built up. These axes 
are assumed to intersect in the centre of the crystal, and pass 
through from one side to the other. 
1st, or Regular System.—Three axes, all equal and at right 
angles. The simple forms of this system are (i) the cube 
(F'g- 37) j (2) the regular octohedron (Fig. 38); (3) the rhom- 
Fig. 37- 
Fig. 38. 
bic dodecahedron (Fig. 39); and (4) the regular tetrahedron 
(Fig. 40). The following are a few of the substances crystal- 
lizing in this system—alum, common salt, diamond, fluor-spar, 
iron pyrites, and garnet. Elementary Chemistry. 
151 
2d, or Quadric System.—Three axes, all at right angles, 
one shorter or longer than the other two. The simple forms 
of this system are the first and second right square prisms 
Fig. 39- 
Fig. 40. 
(Fig. 41 a and b), and the first and second right square octo- 
hedra (Fig. 42 a and b). In the first square prism the axes 
Fig. 41 a. 
Fig. 41 b. 
terminate in the centre of each of the sides, and in the second 
the axes terminate at the intersection of the sides, and this is 
reversed with regard to the octohedra. Some of the common 
substances which crystallize in this system are—yellow prus- 
siate of potash, zircon, and stannic oxide. 
The 3d, or Hexagonal System.—Four axes, three equal 152 
Elementary Chemistry. 
and in one plane, making angles of 6o°, and one longer or 
shorter, at right angles to the plane of the other three. The 
Fig. 42 a. 
Fig. 42 b. 
regular six-sided prism (Fig 43), the regular six-sided pyramid 
(Fig. 44), and the rhombohedron (Fig 45), are the common 
Fig. 43- 
Fig. 44- 
forms of this system. Quartz, calc-spar, beryl, corundum, 
graphite, &c., crystallize in the hexagonal system. 
4th or Rhombic System.—Three axes, all unequal, and all 
at right angles. The chief forms of the crystals in this system 
are the right octohedron with rhombic base (Figs. 46 and 47), 
and the right rhombic prism (Fig. 48). In this system the Elementary Chemistry. 
153 
following substances are found—nitre, barium sulphate, arra- 
gonite, topaz, and native sulphur. 
5th or Monoclinic System.—Three axes, all unequal, two 
Fig. 45- 
Fig. 46- 
CUt one another obliquely, and one is at right angles to the 
plane of the other two. The oblique rhombic octohedron 
(Fig. 49) belongs to this system. Many substances crystal- 
Fig. 47- 
Fig. 48. 
lize in this system ; amongst the most common are—sulphur 
deposited from fusion, sodium carbonate and phosphate, fer- 
rous sulphate, and borax, 
6th, or Triclinic System.—Three axes, all unequal, and all 
oblique. The doubly-oblique octohedron, and the doubly- 
oblique prism (Fig. 50), are the leading forms in this system. 154 
Elementary Chemistry. 
Copper sulphate, boracic acid, the mineral albite, and a few 
other substances are found to crystallize in this system, the 
forms of which are in general very complicated. The crys- 
talline form of copper sulphate is shown in Fig. 51. 
Fig. 49. 
Under one or other of these six divisions all the known 
forms of crystals can be classed. In every distinct crystal 
belonging to any one of these systems, in which the axes are 
not all equal, or all at right angles, certain relations exist be- 
Fig. 50. 
tween the lengths of the axes, and these have certain mutual 
inclinations to one another. These relations and inclinations 
vary with different substances, but are constant for the same ; 
so that different bodies all crystallizing in the same system, Elementary Chemistry. 
155 
as a rule, have different relations between the lengths of the 
axes, and these generally have different inclinations to one 
another. 
Certain substances exhibiting a similarity in their chemical 
Fig. 51. 
constitution are found to crystallize in the same forms : these 
are said to be isomorphous ; whilst, when the same body 
occurs crystallized in two different systems, it is said to be 
dimorphous. Examples of these peculiar relations between 
chemical composition and crystalline form will be given later 
on. 
LESSON XIX. 
Class I. Metals of the Alkalies.—1, Potassium. 
2, Sodium. 3, Cesium. 4, Rubidium. 5, Lithium. (6, 
Ammonium.) 
Potassium. Symbol K. Combining Weight 39T. Specific 
Gravity o-865. 
The metal potassium was discovered in the year 1807, by 
Sir Humphrey Davy, who decomposed the alkali potash into 
the metal, hydrogen, and oxygen, by means of a powerful 
galvanic current. Before this time the alkalies and alkaline 1S6 
Elementary Chemistry. 
earths were supposed to be elementary bodies. The metal is 
now prepared by heating together potash and carbon to a 
high temperature in an iron retort. The carbon, at the high 
temperature, is able to take the oxygen from the potash, form- 
ing carbonic oxide, which escapes as a gas, whilst the metal 
potassium, which is volatile at a red heat, distils over. The 
preparation of this metal is attended with many difficulties, 
and requires special precautions, as the vapor of potassium 
not only takes fire when brought in contact with the air, but 
decomposes water, combining with the oxygen and liberating 
hydrogen ; hence the metallic vapor must be cooled by rock 
oil or naphtha, which contains no oxygen. The metal thus 
prepared must be distilled a second time, in order to purify 
it and free it from a black, explosive compound, which inva- 
riably forms in the original preparation, and has caused sev- 
eral fatal accidents. 
Potassium, thus prepared, is a bright, silver-white metal, 
which can be easily cut with a knife at the ordinary atmo- 
spheric temperature ; it is brittle at o°, and melts at 62°'5, 
and does not become pasty before melting; when heated to a 
temperature below red heat, potassium sublimes, yielding a 
fine green-colored vapor. This metal rapidly absorbs oxygen 
when exposed to the air, and gradually becomes converted 
into a white oxide. Thrown into water, one atom of potas- 
sium displaces one of hydrogen from the water, forming 
potassium hydroxide, KHO ; this takes place with such force 
that the heat developed is sufficient to ignite the hydrogen 
thus set free, and the flame becomes tinged with the peculiar 
purple tint characteristic of the potassium compounds, whilst 
the water attains an alkaline reaction from the potash which 
is formed. Potassium combines also with chlorine and sul- 
phur, and many other metalloids, evolving, when heated with 
these substances, heat and light. 
Sources of the Potassium Compounds.—The original source 
of potassium compounds is in the felspar of the granitic rocks, 
of which the earth is composed, as these contain from two to 
three per cent, of this metal. Up to the present time, this Elementary Chemistry. 
157 
source has not been available for the manufacture of the 
potassium salts, as no cheap and easy mode has yet been 
made available for separating the potash from the silicic acid, 
with which it is combined in felspar. Plants, however, are 
able slowly to separate out and assimilate the potash from 
these rocks and soils ; so that, by burning the plant and ex- 
tracting the ashes with water, soluble potash-salt is obtained. 
This is the crude potassium carbonate, called, when purified 
by recrystallization, pearl-ash, and it is from this substance 
that a large number of the potassium compounds are obtained. 
Some of the other potassium salts, such as the nitrate and 
chloride, are found in large quantities in various localities as 
deposits on the surface, or in the interior, of the earth. 
Potassium chloride occurs in beds together with rock salt, 
in Stassfurt in Germany, Another inexhaustible source of 
potassium compounds, which, however, has only just begun 
to be utilized, is sea-water ; a plan has lately been proposed 
by which those compounds can be obtained from the sea. 
Potassium Oxides.—Potassium combines with oxygen in 
three proportions, forming three well-defined oxides of the 
formulae— 
(1) Potassium monoxide KaO 
(2) Potassium dioxide K2Oa 
(3) Potassium tetroxide KaO* 
These oxides are unimportant bodies ; but potash, the 
compound of the first with water, is a substance of great 
importance. 
Potassitim monoxide, K,0, is obtained by allowing thin 
pieces of the metal to oxidize in dry air ; it is a grayish-white, 
brittle substance, which melts a little above red heat, and 
volatilizes only at a very high temperature. This oxide com- 
bines with water with evolution of great heat, producing 
potassium hydroxide, or potash, from which water cannot 
again be separated by heat. The reaction may be repre- 
sented as an exchange of hydrogen for potassium, thus ; 
KaO + HaO = 2(KHO). 158 
Elementary Chemistry. 
Potassium Hydroxide, or Caustic Potash, HKO, is ob- 
tained as above, or more conveniently prepared by boiling 
one part of potassium carbonate with twelve parts of water, 
and adding slacked lime prepared from two-thirds part of 
quick lime. In this reaction calcium carbonate is formed, 
which falls to the bottom as a heavy powder, caustic potash 
remaining in solution. The clear liquid, which should not 
effervesce on addition of an acid, is evaporated in a silver 
basin to dryness, fused by exposure to a stronger heat, and 
cast into sticks in a metallic mould. Thus prepared, caustic 
potash is a white substance, soluble in half its weight of 
water, acting as a powerful cautery, destroying the skin. It 
5? largely used in the arts and manufactures, and is employed 
in the laboratory for various purposes. 
Potassium Carbonate. Symbol K2COs. This salt re- 
ceives the commercial name of potashes, or pearl-ashes, and 
is imported in large quantities from Russia and America. The 
crude substance is prepared by boiling out the ashes of 
plants with water, and evaporating the solution to dryness ; a 
pure salt may be afterwards obtained by separating the im- 
purities by crystallization. The leaves and small twigs of 
plants contain more potash than the stems and large 
branches. Potassium carbonate can be obtained perfectly 
pure by heating pure potassium tartrate to redness, and 
separating the carbonate formed by dissolving in water. This 
salt absorbs water from the air, or is deliquescent, and is, 
therefore, very soluble in water ; it also turns red litmus blue, 
or possesses a strongly alkaline reaction. 
Hydric Potassium Carbonate, HKCOs. This substance is 
formed when a current of carbonic acid gas, C02, is passed 
through a strong solution of the preceding salt. It may be 
considered as dibasic carbonic acid, H2C02, in which one atom 
of hydrogen is replaced by one of potassium. It is a white 
salt, not so soluble as potassium carbonate ; the solution is 
nearly neutral to test paper. 
Potassium Nitrate, Nitre, or Saltpetre, KNOs. This im- 
portant salt occurs as an efflorescence on the soil of several Elementary Chemistry. 
159 
dry tropical countries, especially that of India. It may be 
artificially prepared by the process of nitrification, in which 
animal matter (containing nitrogen) is exposed in heaps, 
mixed together with wood-ashes and lime, to the action of the 
air ; the organic matter gradually undergoes oxidation, nitric 
acid being formed, and this unites, first with the lime and 
then with the potash, to form nitre. The salt is obtained 
from both of these sources by boiling out the soil or deposit 
with water, and allowing the nitre to crystallize out. Nitre 
crystallizes in rhombic prisms ; it dissolves in seven parts of 
water, at 150, and in its own weight of hot water. It contains 
nearly half its weight of oxygen, with which it parts on heat- 
ing with carbon or other combustible matter. For this rea- 
son, nitre is largely used in the manufacture of gunpowder 
and fireworks. Gunpowder consists of an intimate mixture 
of nitre, charcoal, and sulphur. The general decomposition 
which occurs when gunpowder is fired may be expressed by 
saying that the oxygen of the nitre combines with the char- 
coal, forming carbonic acid and carbonic oxide; whilst the 
nitrogen is liberated, and the sulphur combines with the 
potassium. Hence gunpowder can burn under water or in a 
closed space, as it contains the oxygen needed for the com- 
bustion in itself, and the great explosive power of the sub- 
stance is due to the violent evolution of large quantities of 
gas, and a rapid rise of temperature causing an increase of 
bulk sudden and great enough to produce what is termed an 
explosion. It has been found by practice that the best gun- 
powder is that which contains nearly two atoms of nitre, one 
of sulphur, and three of carbon ; but the decomposition which 
actually occurs in the explosion is a more complicated one 
than has been expressed above, and cannot be represent- 
ed in an equation. The following table (see p. 160) gives 
the composition of musketry powder, as manufactured by 
different nations. 
Potassium combines with sulphur to form several com- 
pounds, of which the best known are K2S, KjSa, K2S3, and 
K3S5. They are soluble substances, which evolve sulphu- 160 
Elementary Chemistry. 
retted hydrogen when heated with an acid, and are not used 
in the arts. 
English 
and 
Austrian. 
Prussian. 
Chinese. 
French. 
Nitre 
75 
75 
757 
75-0 
Charcoal .... 
15 
13-5 
144 
125 
Sulphur .... 
10 
n-5 
9‘9 
12-5 
100 
100-0 
100-0 
100-0 
The remaining compounds of potassium of interest and im- 
portance are—potassium chloride, KCI, occurring in sea-water 
and also in certain deposits ; potassium iodide, KI, men- 
tioned under the head of Iodine ; potassium bromide, K Br 
{see ante, p. 95); potassium chlorate, KCI Os, the prepara- 
tion of which was described under Hydric Chlorate, (p. 93) ; 
potassium sulphate, K2SO4, one of the most insoluble of the 
salts of this metal ; and hydric potassium sulphate, HKSO4. 
General Characteristics of the Potassium Compounds. 
All the potassium compounds impart a violet color to the 
flame, and the spectrum of this flame {see p. 220, spectrum 
analysis) is distinguished by the presence of two bright lines, 
one in the red, and another in the violet. Almost all the 
potassium salts are soluble in water ; the three which are 
least soluble are—(1) potassium perchlorate ; (2) hydric- 
potassium tartrate, which is precipitated in the form of a 
white crystalline powder, when a solution of a potassium salt 
is mixed with an excess of tartaric acid; and (3) potassium- 
platinum chloride, 2(KC1) + Pt Cl4, which precipitates in small 
yellow cubical crystals, when platinum chloride solution is 
added to a soluble potassium salt. These reactions serve to 
distinguish the potassium salts. Elementary Chemistry. 
161 
2. Sodium. Symbol Na {natrium). Combining Weight 
23. Specific Gravity 0-97. 
This metal was discovered by Sir H. Davy immediately 
after the isolation of potassium, by the decomposition of soda 
with the galvanic current. It can be procured more easily 
than potassium by reducing the carbonate in presence of 
carbon, and is now manufactured in large quantities for 
the preparation of other metals, especially magnesium and 
aluminium. The apparatus employed for the preparation of 
this metal is the same as that used for potassium ; the metal 
distils over when condensed, and drops into rock oil. So- 
dium is a silver-white metal, soft at ordinary temperatures, 
and melting at 95°'6 ; it volatilizes below a red heat, yielding 
a colorless vapor. When thrown upon water it floats, and 
rapidly decomposes the water with disengagement of hydro- 
gen, soda being formed. If the water be hot or be thickened 
with starch, the globule of metal becomes so much heated as 
to enable the hydrogen to take fire. The compounds of 
sodium are very widely diffused, being contained in every 
speck of dust {see spectrum analysis, p. 221); they exist in 
enormous quantities in the primitive granitic rocks {see p. 8), 
but they are most readily obtained from sea-water, which con- 
tains nearly three per cent, of sodium chloride (common or 
sea-salt), or from the large deposits of this substance which 
occur in Cheshire, Galicia, &c. Sodium carbonate was 
formerly obtained from the ashes of sea-plants or kelp, 
as potassium carbonate is still prepared from the ashes of 
land plants ; but at present the sodium carbonate is alto- 
gether manufactured, on an enormously large scale, from sea 
salt. 
Sodium Oxides. There are two compounds of sodium and 
oxygen known. Sodium oxide, Na2 O ; and sodium dioxide, 
Na2 02—Sodium Oxide, Na2 O, is formed when sodium is 
oxidized in dry air or oxygen at a low temperature, a white 
powder being formed ; this takes up moisture with great avidity, 
forming H Na O, sodium hydroxide, or soda, from which the 
water cannot again be separated by heat alone, but which can Elementary Chemistry. 
162 
again be converted into the oxide by heating with sodium; 
thus, H NaO + Na = Na20 + H. 
Sodium Dioxide, Na2 Oa, is a yellowish-white powder, 
which is formed when sodium is heated in oxygen to 200° C. ; 
it is soluble in water, but the solution readily decomposes, 
giving off oxygen and leaving sodium hydrate. Sodium 
dioxide is not used in the arts. 
Sodium Hydroxide, or Caustic Soda, H Na O, is a white 
solid substance, fusible below a red heat, and less volatile 
than the corresponding potassium compound. It is very solu- 
ble in water, acts as a caustic, is powerfully alkaline, and is 
largely used in soap-making. The manufacture of solid caus- 
tic soda is now carried on on a large scale, by boiling lime and 
sodium carbonate together with water, and evaporating down 
the clear solution. 
Ca O + Na2 C03 + H20 = Ca C03 + 2{HNa O). 
Sodium Chloride—Common Salt. Na Cl. It is from this 
salt that almost all the other sodium compounds are prepared. 
Sodium chloride occurs in thick beds in various parts of the 
world, especially in Cheshire, Galicia, Tyrol, Spain, and 
Transylvania. It is likewise prepared from sea-water by 
evaporation or by freezing ; and from certain brine springs by 
evaporation. When slowly deposited sodium chloride crys- 
tallizes in regular cubes, it is soluble in about two and a half 
parts of water at 15°, and does not dissolve sensibly more in 
hot than in cold water. 
Sodium Carbonate, Na2 C03. This substance, known in 
commerce as soda-ash, is manufactured in England on an 
enormous scale, and used for glass-making, soap-making, 
bleaching, and various other purposes in the arts. Formerly 
it was prepared from barilla or the ashes of sea-plants, but 
now it is wholly obtained from sea-salt by a series of chemical 
decompositions and processes, which may be divided into two 
stages. 
(1) Manufacture of sodium sulphate, or salt-cake, from 
sodium chloride (common salt) ; called salt-cake process. Elementary Chemistry. 
163 
(2) Manufacture of sodium carbonate, or soda ash, from 
salt cake ; called soda-ash process. 
(1) Salt-cake process. This process consists in the decom- 
position of salt by means of sulphuric acid : this is effected in 
a furnace called the Salt-cake Ftirnace. Fig. 52 shows the 
section, and Fig. 53 the elevation of such a furnace : these are 
Fig. 52. 
Fig. S3- 
drawn to scale from one actually in use. It consists of (1) a 
large covered iron pan placed in the centre of the furnace, 
and heated by a fire placed underneath ; and (2) two roasters 
or reverberatory furnaces, placed one at each end, and on the 
hearths of which the salt is completely decomposed. The 
charge of half a ton of salt is first placed in the iron pan, and 
then the requisite quantity of sulphuric acid allowed to run in 
upon it. Hydrochloric acid gas is evolved, and escapes 
through a flue with the products of combustion into towers, 
or scrubbers, filled with coke or bricks moistened with a 
stream of water ; the whole of the acid vapors are thus con- 
densed, and the smoke and heated air pass up the chimney. 
After the mixture of salt and acid has been heated for some 
time in the iron pan, and has become solid, it is raked by 
means of the doors seen in Fig. 53, on to the hearths of the 
furnaces at each side of the decomposing pan, where the 164 
Elementary Chemistry. 
flame and heated air of the fire complete the decomposition 
into sodium sulphate and hydrochloric acid. 
(2) Soda Ash process. This process consists (1) in the 
preparation of sodic carbonate, and (2) in the separation and 
purification of the same. The first chemical change which 
the salt-cake undergoes in its passage to soda-ash, is its 
reduction to sulphide by heating it with powdered coal or 
slack; 
Na2 SO4 -f- C4 — Na2 S + 4 CO. 
The second decomposition is the conversion of the sodium 
sulphide into sodium carbonate, by heating it with chalk or 
limestone (calcium carbonate): 
Na2S + Ca C03 = Na2 C03 + Ca S. 
These two reactions are in practice carried on at once ; a 
mixture of of salt cake, ten parts of limestone, and 
seven and a half parts of coal being heated in a reverberatory 
furnace called the Balling Furnace (shown in section in Fig. 
54, and in elevation in Fig. 55), until it fuses and the above 
Fig. 54- 
decomposition is complete, when it is raked out into iron 
wheelbarrows to cool. This process is generally termed the 
black-ash process, from the color of the fused mass. 
The next operation consists in the separation of the sodic 
carbonate from the insoluble calcium sulphide and other im- 
Fig. ss- Elementary Chemistry. 
165 
purities. This is easily accomplished by lixiviation, or dis- 
solving the former salt out in water. On evaporating down the 
solution, for which the waste heat of the black-ash furnace is 
used, the heated air passes over a leaden pan (shown in Fig. 
54) containing the liquid. On calcining the residue, the soda- 
ash of commerce is obtained. No less than 200,000 tons of 
common salt are annually consumed in the alkali works of 
Great Britain, for the preparation of nearly the same weight 
of soda-ash, of which the value is about two millions sterling. 
The soda-ash of commerce contains from 48 to 56 per cent, 
of pure caustic soda, Naa O, as carbonate and hydrate, the 
remainder being impurities, consisting generally of sulphate, 
sulphite, and chloride. If soda-ash be dissolved, and the 
saturated solution allowed to stand, large transparent crystals 
(monoclinic) of the hydrated carbonate, of the formula Naa 
COs + 10H2O separate out; this substance is commonly 
known as soda-crystals, and is much used for softening water 
for washing purposes. 
Hydric-Sodium Carbonate, or Bicarbonate of Soda, H Na 
COs, is obtained by exposing the crystallized carbonate in an 
atmosphere of carbonic acid gas. It is a white crystalline 
powder, which on heating is readily converted into sodium 
carbonate. The bicarbonate is chiefly used in medicine, and 
for the production of effervescing drinks. 
The other sodium salts of importance are sodium nitrate or 
Chili saltpetre, Na NOs, found in Northern Chili in large 
beds, imported in large quantities, and chiefly used as a 
manure ; sodium sulphate, or Glauber salts, Na2 SO4 + 10H2 
O (in the anhydrous state known as salt-cake) ; hydric sodium 
sulphate (or bisulphate), H Na S04; sodium hyposulphite, 
NasSstGCb + 4 Hj O, mentioned under the compounds of 
sulphur and oxygen (p. 113) ; the sodium phosphates, men- 
tioned under phosphorus (p. 130); borax, Na20 2B2O3 +10 
H20 (see p. 125); sodium sulphide, Na2 S, a soluble salt 
formed by reducing the sulphate with carbon ; sodium sili- 
cates, or soluble glass (see p. 175). 
General Characteristics of the Sodium Compounds. All 166 
Elementary Chemistry. 
the sodium salts, with the single exception of the antimoniate, 
are soluble in water. The presence of sodium compounds 
can be detected by the peculiar yellow tinge which they im- 
part to the flame. The spectrum of sodium is distinguished 
by one fine bright double line, identical in position with the 
dark solar line called D. 
3 and 4. Cesium and Rubidium. Ca2 = 133. Rb = 
85-4. 
These two metals were discovered in 1860-61 by Bunsen 
and Kirchoff, by means of spectrum analysis {see p. 221). 
They so closely resemble one another and potassium in their 
chemical properties, that they had previously been mistaken 
for the latter well-known metal. They occur widely dis- 
tributed, although generally occurring in small quantities. 
They were originally discovered in the mineral water of 
Diirkheim, but since that time they have been found in many 
other springs, in several kinds of mica and other old plutonic 
silicates, as well as in the ashes of several plants, viz. beet- 
root, tobacco, coffee, and grapes. These metals can be 
separated from potassium by the greater insolubility of the 
double chloride which they form with platinum ; if a mixture 
of K, Cae, and Rb salts be completely precipitated by platinic 
chloride and the precipitate boiled out with water, the insolu- 
ble residue will contain the new metals. Caesium may be 
separated from rubidium by the greater solubility of the acid 
tartrate of the former metal. The salts of caesium and rubi- 
dium are isomorphous with the corresponding potassium com- 
pounds. The fused chlorides of these metals are easily 
decomposed by the galvanic current, and the metallic element 
deposited. The metals can also be prepared by reduction 
with carbon, as potassium. Rubidium is a white metal which 
rapidly undergoes oxidation, its specific gravity is i'$2, and it 
forms a greenish-blue vapor. Caesium is the most electro- 
positive of the metals. 
5. Lithium. Symbol Li. Co7nbining Weight 7. Specific 
Gravity C59. Elementary Chemistry. 
167 
This metal is prepared by decomposing the fused chloride 
by electricity; it is of a white color, it fuses at 180°, and is 
the lightest metal known. The lithium salts were formerly 
supposed to be very rare, only being known to occur in three 
or four minerals, but spectrum analysis has shown that this is 
a widely-distributed substance ; it occurs in small quantities 
in almost all waters, in milk, tobacco, and even in human 
blood. A spring in Cornwall contains large quantities of this 
metal in the form of chloride. Lithium in its chemical rela- 
tions stands between the class of alkaline and alkaline-earth 
metals, the hydrate, carbonate, and phosphate, being only 
sparingly soluble in water. All the volatile lithium com- 
pounds impart a magnificent crimson tinge to the flame, and 
the spectrum of this flame exhibits the presence of one bright 
and very characteristic red line, by means of which the pres- 
ence of the minutest trace of this substance can be detected 
with certainty and ease. 
6. Ammonium and the Salts of Ammonia. 
With the class of alkaline metals the ammoniacal salts may 
conveniently be considered, as in their chemical properties 
they present a remarkable analogy with the salts of the alka- 
lies proper. In all these salts the existence of a quasi-metal 
called Arnmonium, NH4, is supposed, and if this substance 
be substituted for an atom of potassium or sodium in the 
alkaline salts, a corresponding salt of ammonium is formed 
thus.: 
Potassium chloride, KC1. 
Ammonium chloride, NH4 Cl. 
Potassium sulphate, Ka S04. 
Ammonium sulphate, 2 (NH4) S04. 
Ammonium itself has not yet been prepared in the pure 
state, but an amalgam of ammonium and mercury is known, 
and the existence of this compound appears to show that the 
body NH4 acts like a metal. The most important of the 
ammoniacal salts, which are all volatile, are ammonium- 
chloride, or sal-ammoniac, NH4 Cl, originally prepared by 168 
Elementary Chemistry. 
subliming camel’s dung, but now obtained by neutralizing the 
ammoniacal water of the gas works {see p. 80) with hydro- 
chloric acid, evaporating the liquor to dryness, and by sub- 
liming the volatile sal-ammoniac. The sulphate, 2 (NH4) 
S04, is likewise prepared from gas-liquor by neutralization 
with sulphuric acid. The carbonate, nitrate, and sulphide of 
ammonium correspond closely to the same potassium salts. 
The salts of ammonia can easily be recognized by their giving 
off an alkaline gas possessing a pungent smell of ammonia 
when they are heated with caustic lime or a caustic alkali. 
The acid tartrate and the double platinic chloride are both 
insoluble, and resemble the corresponding potash cympounds 
so closely that the two sets of salts cannot be distinguished 
by means of these tests. In order to test for potash in pres- 
ence of ammoniacal salts, all the latter must first be driven off 
by heating.* 
LESSON XX. 
Class II. Metals of the Alkaline Earths. 
These are three in number—1. Calcium, 2, Strontium, 
and 3. Barium ; they chiefly differ from the preceding metals 
by forming insoluble carbonates, sulphates, phosphates, and 
oxalates. 
i. Calcium. Symbol Ca. Combining Weight 40. Spe- 
cific Gravity i'58. 
Calcium forms a considerable portion (see p. 8) of the plu- 
tonic rocks of which the earth is composed, and occurs in 
very large quantities, forming whole mountain chains of lime- 
stone, chalk, gypsum, and mountain limestone. The metal 
• Ammonia, NHs, is only the first term of a series of volatile bodies possessing 
closely-similar properties and forming definite salts; these bodies will be described 
in the part relating to organic chemistry. Elementary Chemistry. 
169 
calcium is obtained by the decomposition of the chloride by 
the electric current, or by heating the iodide with sodium ; it 
is a light yellow metal which easily oxidizes in the air, and 
when heated in air it burns with a bright light—lime, CaO, 
the only oxide of calcium, being formed. 
Calcium Oxide, or Lime, CaO. Pure lime is obtained by 
heating white or black marble to redness in a vessel exposed 
to the air. Lime is prepared on a large scale for building and 
other purposes, by heating limestone (the carbonate) in kilns 
by means of coal mixed with the stone ; the carbonic acid 
escapes, and quick- or caustic-lime remains. Pure lime is a 
white infusible substance, which combines with water very 
readily, giving off great heat, and falling to a white powder 
called calcium hydrate, or slacked lime, CaO H20. The 
hydrate is slightly soluble in water, I part of it dissolving in 
730 parts of cold, but only in 1300 parts of boiling water, and 
forming lime-water, which, like the hydrate, has a great power 
of absorbing carbonic acid from the air. It is indeed partly 
owing to this property that the hardening or setting of mortars 
and cements made from lime is due. Mortar consists of a 
mixture of slacked lime and sand ; a gradual combination of 
the lime with the silica occurs, and this helps to harden the 
mixture. Hydraulic mortars, which harden under water, are 
prepared by carefully heating an impure lime containing 
clay and silica; a compound silicate of lime and alumina 
appears to be formed on moistening the powder, which 
then solidifies, and is unacted upon by water. Lime is 
largely used in agriculture, its action being, 1st, to destroy 
the excess of vegetable matter contained in the soil; and, 
2dly, to liberate the potash for the use of the plants from heavy 
clay soils by decomposing the silicate. 
Calcium Carbonate, or Carbonate of Lime, Ca C03. This 
salt occurs most widely diffused, as chalk, limestone, coral, 
and marble; many of those enormous deposits being made 
up of the microscopic remains of minute sea-animals. Calcium 
carbonate exists crystalline as calc spar, or Iceland spar 
(rhombohedral, or hexagonal system, Fig. 45), and also in a Elementary Chemistry. 
different form, arragonite (rhombic, Fig. 46), so that this sub- 
stance is dimorphous. The carbonate is almost insoluble in 
pure water, but readily dissolves when the water contains car- 
bonic acid, giving rise to what is termed temporarily hard 
water. Such a water deposits a crust of calcium carbonate 
on boiling, owing to the escape of the carbonic acid. The 
well-known evil of boiler crust is caused by these deposits : 
the formation of such a crust may be checked if not avoided 
by adding a small quantity of sal-ammoniac to the water, 
soluble calcium chloride and volatile ammonium carbonate 
being formed. Water hard with dissolved carbonate may be 
softened by the addition of lime suspended in water in 
such quantity that the excess of carbonic acid is neutra- 
lized. 
Calcium Sulphate, Ca SCb. This occurs in nature as a 
mineral termed Anhydrite, and combined with 2 HaO as 
selenite, gypsum, or alabaster. It is soluble in 400 parts of 
water, and is a very common impurity in-spring water, giving 
rise to what is termed permanent hardness, as it cannot be 
removed by boiling. Gypsum when moderately heated loses 
its water, and is then called plaster of Paris ; this when 
moistened takes up two atoms of water again and sets to a 
solid mass, and is therefore much used for making casts and 
moulds. 
Calcium Chloride, Ca Cl2. This soluble salt is formed 
when limestone or marble is dissolved in hydrochloric acid 
(see p. 70); if the solution be then evaporated, colorless 
needle-shaped crystals of the hydrated chloride, Ca CU + 6 
H20, are formed. When these are dried the substance still 
retains 2 H20, and forms a porous mass which takes up 
moisture with great avidity, and is much used for drying gases. 
When this mass is more strongly heated it fuses and parts 
with all its water. 
Calcium Fluoride, Fluor spar, Ca Fj. Found crystallized 
in cubes in Derbyshire and Cumberland. When heated with 
sulphuric acid, calcium sulphate and hydrofluoric acid (see p. 
100) are formed. It is sometimes used as a flux in the reduc- Elementary Chemistry. 
171 
tion of metals, whence its name Fluor Spar is derived. The 
foregoing are the most important salts of calcium. 
Among the remaining compounds of calcium may be 
mentioned bleaching-powder, or chloride of lime, Ca Cb Ca 
2 CIO, the properties and mode of preparation of which salt are 
described on p. 92 ; calcium phosphate, or bone-phosphate, 
Ca3 2 P04 (see p. 129) ; calcium sulphide, Ca S, an insoluble 
substance formed in the soda-ash process (see p. 164); and 
calcium penta-sulphide, Ca S5, a soluble salt. The spectrum 
of calcium is a very peculiar one, containing a number of 
distinct bright lines by which the presence of this metal can 
be easily ascertained. 
2. Strontium. Symbol Sr. Combining Weight 87‘5. 
This element occurs in much smaller quantities than cal- 
cium, or even barium, being found in only a few mineral 
species, especially strontianite the carbonate, and celestine 
the sulphate. Strontium likewise occurs in minute quantities 
in certain spring waters. The metal has a yellowish-white 
color, and is prepared by the action of a current of electricity 
on the fused chloride. It resembles calcium closely in its 
properties ; its specific gravity is 2*54. When heated in the 
air it burns, forming the monoxide strontia. 
Strontium Oxide, or Strontia, Sr O. This oxide is best 
obtained by decomposing the nitrate by heat; it unites with 
water, evolving great heat, and forming the hydrate Sr O + 
9 Hj O; this is soluble in water, and absorbs carbonic acid 
with avidity. The native salts of strontium, viz., the car- 
bonate and sulphate, are insoluble, and serve for the prepara- 
tion of the remaining salts. The nitrate, Sr 2 N03, and the 
chloride, Sr CU, are soluble in water; these are the only 
salts of this metal which are employed in the arts, and these 
are used for the preparation of red fires, as the volatile salts 
of strontium have the power of coloring the flame crimson. 
The spectrum of strontium is a very characteristic one, and 
by this means the minutest trace of this substance can be 
easily and certainly detected, even in presence of calcium and 
barium salts. Elementary Chemistry. 
1/2 
3 Barium. Symbol Ba. Combining Weight 137. 
Barium compounds occur somewhat more widely dispersed 
than those of strontium, the two most common barium min- 
erals being the sulphate, or heavy spar, and the carbonate, 
or witherite. The metal barium has not yet been obtained 
in the coherent state, but the metallic powder may be pre- 
pared in a similar way as the two former metals, which it 
closely resembles in its properties. 
Barium Monoxide, or Baryta, Ba O. The best way of 
forming this oxide is to decompose the nitrate by heat ; it 
is a grayish porous mass, which fuses at a high temperature, 
and takes up water with evolution of much heat, forming a 
crystalline hydrate, HU Ba 02 + 8 HU O. This hydrate is 
soluble in twenty parts of cold water, and the solution on 
exposure to the air rapidly absorbs carbonic acid and be- 
comes milky. 
Barium Dioxide, Ba CU. When baryta is gently heated in 
a current of oxygen gas, the two substances combine together 
to form a dioxide containing twice as much oxygen as baryta ; 
this additional atom of oxygen is, however, evolved at a high- 
er temperature, and it has been proposed to use this decom- 
position for the manufacture of oxygen from the air. For this 
purpose, as soon as the dioxide Ba02 has been reduced to Ba 
O, the temperature is lowered, and air passed over the baryta; 
this again takes up oxygen, passing into Ba 02, which again is 
decomposed by a higher temperature. This interesting pro- 
cess has, however, been found not to work in practice. There 
are no salts known corresponding to this oxide. 
Barium Chloride, Ba Cls. This soluble salt is one of the 
most important compounds of barium ; it crystallizes in flat 
scales containing two atoms of water. It may be prepared by 
dissolving the native carbonate in hydrochloric acid, and it is 
largely used as a precipitant for sulphuric acid. Barium Sul- 
phate, Ba SO4, occurs native and crystalline as heavy spar; 
specific gravity 46 (whence the name Barium, from papvs 
(heavy). It is one of the most insoluble salts known, and falls 
as a white crystalline precipitate when any soluble barium salt Elementary Chemistry. 
173 
is brought into a solution of a sulphate. It is used as a paint, 
and the precipitated salt is termed blancfixe, whilst the na- 
tive heavy spar, when ground, is largely used to adulterate 
white lead (see p. 205). 
The other more Important salts of barium are the nitrate 
Ba 2NO3, a soluble salt; the sulphide, a soluble salt, BaS, 
obtained by heating heavy spar with coal and dissolving in 
water; the carbonate, Ba C03, an insoluble substance, occur- 
ring native as witherite : the silicofluoride and the phosphate 
are insoluble salts, whilst strontium silicofluoride is soluble in 
water. The volatile salts of barium have the power of com- 
municating a peculiar green color to the flame, and the spec- 
trum of barium contains a number of characteristic green 
lines, by means of which the presence of minute traces of this 
substance can be detected. 
Class III. Metals of the Earths. 
I. Aluminium. Symbol Al. Combining Weight 
Specific Gravity 2’6. 
This metal occurs in large quantities combined with silicon 
and oxygen in felspar and all the older rocks, and also in 
clay, marl, slate, and in many crystalline minerals. Metallic 
aluminium is obtained by passing the vapor of aluminium 
chloride over metallic sodium. It has recently been manufac- 
tured on a large scale both in England and France, and, from 
its lightness (specific gravity 2-6) and its bright lustre, it has 
been used for optical purposes as well as for ornamental work. 
Alumina, AU 03, specific gravity, 39. This is the only 
oxide of aluminium known. It occurs native in a nearly pure 
and crystalline state as corundum, ruby, sapphire, and emery. 
Alumina is prepared by adding ammonia to a solution of 
alum ; a white precipitate of the hydrate falls down, and this 
on being heated yields a white amorphous powder of pure 
alumina. This substance is attacked with difficulty by acids, 
but the hydrate is easily soluble in acids and in the fixed caus- 
tic alkalies. Alumina acts as a weak base; the commonest 174 
Elementary Chemistry. 
aluminium salts are the alums, and their solutions have an 
acid re-action. Alumina is largely used in dyeing and calico- 
printing as a mordant, as it has the power of forming insolu- 
ble compounds called lakes with vegetable coloring matter, 
and thus renders the color permanent by fixing it in the pores 
of the cloth so that it cannot be washed out; such colors are 
termed fast. 
Aluminium chloride, Al2 Cl6, is a volatile white solid body, 
obtained by heating a mixture of alumina and charcoal in a 
current of chlorine gas ; it is used in the manufacture of the 
metal. 
The soluble aluminium sulphate, AU3SO4, is prepared on a 
large scale for the use of the dyer by decomposing clay by act- 
ing upon it with sulphuric acid; the solid mixture of silica 
and aluminium sulphate thus obtained goes by the name of 
alum-cake. The most useful compounds of alumina are, how- 
ever, the alums, a series of double salts, which aluminium sul- 
phate forms with the alkaline sulphates. Cotmnott potash 
alum, or aluminium potassium sulphate, has the composition 
Ah K2 4S04 + 24Ha O, and crystallizes in regular octohedra 
(Fig. 38). It may be prepared by dissolving the two sulphates 
together, and allowing the compound salt to crystallize, but it 
is usually obtained from the decomposition of a shale or clay 
containing iron pyrites, Fe S2; this substance gradually un- 
dergoes oxidation when the shale is roasted, absorbs oxygen 
from the air producing sulphuric acid, which unites with the 
alumina of the clay, and on the addition of a potassium com- 
pound, alum crystallizes out. A salt called ammonium alum, 
and containing N H4, instead of K, is at present prepared on 
a large scale, the ammonia liquor of the gasworks, together 
with sulphuric acid, being added to the burnt shale, instead 
of a potash salt. 
There are a large number of other alums known, in which 
the isomorphous sesquioxides of iron, chromium, and man- 
ganese, are substituted for the alumina in common alum ; all 
these alums occur in regular octohedra, and cannot be sepa- 
rated by crystallization when present in solution together. Elementary Chemistry. 
175 
Clay is an aluminium-silicate resulting from the disintegration 
and decomposition of felspar by the action of air and water, 
the soluble alkali being washed away. Kaolin or porcelain 
clay is the purest form of disintegrated felspar, containing no 
iron or other impurities. There are many very beautifully 
crystalline minerals, consisting of aluminium silicates com- 
bined with silicates of the metals of the alkalies and alkaline 
earths ; amongst others, garnet, idocrase, mica, lepidolite, &c. 
Some silicates, such as stilbite, analcime, &c., retain water of 
crystallization, and are termed zeolites. Aluminium salts can 
be detected when in solution by giving with ammonia a white 
precipitate, insoluble in excess, but soluble in caustic soda; 
and by assuming a blue color when moistened with cobalt so- 
lution and heated before the blowpipe. 
Glass, Porcelain, and Earthenware. 
The silicates of the alkalies are, as we have seen, soluble in 
water and non-crystalline ; those of the alkaline earths are 
soluble in acid and crystalline, whilst compounds of the two 
are insoluble in water and acids, and do not assume a crystal- 
line form. Such a compound when fused is termed a glass. 
There are four different descriptions of glass used in 
the arts, differing in their chemical composition and ex- 
hibiting corresponding differences in their properties. (1) 
Crown or window and plate-glass, composed of silicates 
of soda and lime. (2) Bohemian glass, consisting of si- 
licates of potash and lime. (3) Flint-glass or crystal, con- 
taining silicates of potash and lead oxide; and (4) Common 
green bottle-glass, composed of silicates of soda, lime, oxide 
of iron, and alumina. The first and third of these kinds of 
glass are easily fusible, whilst the second or potash glass is 
much more infusible ; the addition of oxide of lead increases 
the specific gravity, and the lustre of the glass, as well as its 
fusibility. The common glass articles of household use are 
generally made of flint glass, whilst for chemical apparatus a 
soda-lime-glass is to be preferred. The potash-lime-glass is 
much employed where a difficultly fusible, or hard, glass is 176 
Elementary Chemistry. 
needed, as for instance in the manufacture of combustion 
tubes for organic analysis {see p. 236). The fourth description 
of glass is an impure mixture of various silicates, employed 
for purposes in which the colors and fineness of the glass is 
not of consequence. 
In the preparation of all the fine qualities of glass, great 
care is requisite in the selection of pure materials, as well as 
in the processes of manufacture; generally the materials are 
melted together with a quarter to half their weight of “ cullet” 
or broken glass of the same kind. After the glass articles 
have been blown or cast, they must all be exposed to the pro- 
cess of “ annealing,” or slow cooling, otherwise they are so 
brittle as to be perfectly useless, breaking with the slightest 
touch, owing to the irregular contraction of the different 
parts brought about by rapid cooling. The following table 
shows the composition of the chief varieties of glass. 
Crown Glass. 
Ingredients for Various Glasses. 
Mirror Plate. 
Quartz Sand , . 100 parts. 
Mild Lime . . 36 „ 
Soda Ash . . 24 „ 
Sodium Sulphate 12 „ 
Arsenious Oxide -J- „ 
Gullet . . . 100 „ 
Bohemian Glass. 
Pure Sand . . 100 „ 
Pure Pearlashes 60 „ 
Chalk ... 8 „ 
Gullet ... 40 „ 
Manganese Dioxide I „ 
Pure Sand . .100 parts. 
Soda Ash . . 35 „ 
Mild Lime . . 5 ,, 
Arsenious Oxide i „ 
Gullet. . . .100 „ 
Flint Glass. 
Pure Sand . .100 „ 
Red Lead . 20 „ 
Pearlash. . . 40 „ 
Nitre .... 2 „ 
Gullet . 50 to 100 „ 
Colored Glass. Certain metallic oxides possess the power 
of coloring glass when they are added in small quantity. Thus 
ferrous oxide produces a deep green color (bottle glass), whilst 
the oxides of manganese impart a purple tint to glass; these 
facts are made use of in the preparation of colorless glass, for 
as it is difficult to obtain materials perfectly free from iron, which Elementary Chemistry. 
177 
imparts a green color, a small quantity of manganese dioxide 
is added to the mixture, and the violet color thus produced is 
complementary to the green, and a nearly colorless glass is 
the result. The addition of arsenious oxide effects the same 
end by oxidizing the ferrous to ferric-oxide. The colors of 
precious stones are imitated by adding certain oxides to a 
brilliant lead glass called “ pastethus the blue of the sap- 
phire is given by a small quantity of cobalt oxide, whilst cu- 
prous oxide imparts a ruby-red color, and ferric oxide a yel- 
low color resembling topaz. 
Porcelain and Earthenware. The various forms of porce- 
lain and earthenware consist of silicate of alumina, in fact 
clay, in a more or less pure state, covered with some sub- 
stance which fuses at a high temperature, and forms a glaze, 
giving a smooth surface and binding the material together, 
and thus counteracting the porous nature of the baked clay. 
For the manufacture of porcelain the finest white or China 
clay is used, resulting from the gradual decomposition of fel- 
spar, whilst for the common earthenware a colored clay may 
be employed. The glaze used for porcelain is generally finely 
powdered felspar, the biscuit or porous ware being dipped into 
a vessel containing this substance suspended in water, and 
then strongly fired. The articles thus coated can be used for 
chemical purposes, as this glaze withstands the action of 
acids. For earthenware the so-called “salt glaze” is used ; 
the mode of obtaining this glaze consists in throwing some 
common salt into the furnaces containing the strongly heated 
ware, when the salt is volatilized and undergoes decomposi- 
tion on the heated surface, causing a deposit of a fusible sili- 
cate upon it, and rendering the ware impervious to moisture. 
LESSON XXI. 
Class IV. (i.) Magnesium. (2.) Zinc. (3.) Cadmium. 
1. Magnesium. Symbol Mg. Combining Weight 24-0. 
Specific Gravity 174. 178 
Elementary Chemistry. 
This metal occurs in large quantities as carbonate, along 
with calcium carbonate, in dolo7nite or mountain limestone, 
and also in sea-water and certain mineral springs, as chloride 
and sulphate. The metal itself has only recently been pre- 
pared in quantity ; it is best obtained by heating magnesium 
chloride with metallic sodium, sodium chloride and metallic 
magnesium being formed. This metal is of a silver-white 
color and fuses at a low red heat, it is volatile, and may be 
easily distilled at a bright red heat; when soft it can be 
pressed into wire, and with care it may be cast like brass, 
although when strongly heated in the air it takes fire and 
burns with a dazzling white light, with the formation of its 
only oxide, magnesia. The light emitted by burning magne- 
sium wire is distinguished for its richness in chemically active 
rays, and this substance is therefore employed as a substitute 
for sunlight in photography. 
Magnesium does not oxidize in dry air; it is only slowly 
acted upon by cold water, but more rapidly by hot water ; it 
rapidly dissolves in sulphuric and hydrochloric acids, with 
evolution of hydrogen. 
Magnesium Oxide, or Magnesia, Mg O. A light white 
amorphous infusible powder, obtained by heating the carbon- 
ate or nitrate. It unites with acids to form the magnesium 
salts, but it does not possess a strong alkaline reaction. The 
most important salts of magnesium are :—Magnesium Chlo- 
ride, Mg CU, a fusible salt obtained by heating a solution of 
magnesia in hydrochloric acid with an equal quantity of sal- 
ammoniac ; on fusion, the latter salt volatilizes, and the mag- 
nesium chloride remains behind. Magfieshim Sulphate, 
Mg S04 + 7H2O : this is a soluble substance known as Ep- 
som Salts ; it occurs in a spring in Surrey, and contains 
seven atoms of water of crystallization ; it is now largely 
made from dolomite by separating the lime with the sulphuric 
acid. Magnesium sulphate forms, with the alkaline sulphates, 
double salts, in which the alkaline sulphate takes the place 
of one atom of water of crystallization ; thus, MgSCbKaSO* 
+ 6H2O is the potash double salt. The Carbonate, MgCOs, Elementary Chemistry. 
179 
is an insoluble compound, occurring as a crystallized mineral 
termed magnesite. The magnesia alba of the shops is a 
varying mixture of carbonate and hydrate, made by precipat- 
ing a hot solution of magnesium sulphate with sodium car- 
bonate. Magnesium sulphide is not formed in the wet way. 
Magnesium resembles in many respects the metals of the 
alkaline earths, but it may be distinguished from these by the 
solubility of the carbonate in ammonium chloride, as well as 
by the ready solubility of the sulphate in water. Magne- 
sium forms an insoluble double phosphate with ammonia, 
Mg NHiPCh + 6H20, and it is in this form that the metal is 
usually estimated. 
2. Zinc. Symbol Zn. Combining Weight 6$'2. Specific 
Gravity 6‘8 to 7-2. 
Zinc is an abundant and useful metal, closely resembling 
magnesium in its chemical characters ; but it is much more 
easily extracted from its ores than this latter metal. The 
chief ores of zinc are the sulphide or blende, the carbonate 
or calamine, and the red oxide. In order to extract the 
metal the powdered ore is roasted, or exposed to air at a high 
temperature, so as to convert the sulphide of carbonate or 
carbonate into oxide; the roasted ore is then mixed with 
fine coal or charcoal and strongly heated in crucibles or 
retorts of peculiar shape ; the zinc oxide is reduced by the 
carbon, carbonic oxide gas comes off, and the metallic zinc 
distils over, and is easily condensed. 
Zinc is a bluish-white metal, exhibiting crystalline structure ; 
it is brittle at the ordinary temperature, but when heated to 
about 130°, it may be rolled out or hammered with ease, 
whilst if more strongly heated to 200°, it is again brittle, and 
may be broken up in a mortar. Zinc melts at 423°, and at a 
bright red heat it begins to boil and volatilizes, or if air be 
present it takes fire and burns with a luminous greenish flame, 
forming zinc oxide. Zinc is not acted upon by moist or dry 
air, and hence it is largely used in the form of sheets, and is 
employed as a protecting covering for iron, which when thus Elementary Chemistry. 
coated, is said to be galvanized. Zinc easily dissolves in 
dilute acids with the evolution of hydrogen, and it is thus 
used as the oxidizable portion of the galvanic battery. Brass 
is a useful alloy of one part of zinc and two of copper; 
German silver is an alloy of zinc, nickel, and copper. 
Zinc Oxide, Zn O, is the only known compound of this 
metal with oxygen, and is obtained by burning the metal, or 
by precipitating a soluble zinc salt with an alkali, and heating 
the precipitate. Zinc oxide is an insoluble white amorphous 
powder, which when heated becomes yellow, but loses this 
color on cooling ; it dissolves easily in acids, giving rise to the 
zinc salts. The most important salts of zinc are : Zinc sul- 
phate, Zn SO4 + 7 H20, a soluble salt, crystallizing in long 
prisms, and commonly called white vitriol ; this salt is isomor- 
phous with magnesium sulphate, and like the latter salt it 
forms a series of double salts with alkaline sulphates. The 
chloride, Zn Cl2, a white soluble, deliquescent substance, 
formed by buring zinc in chlorine ; or better, by dissolving 
the metal in hydrochloric acid. The sulphide, Zn S, occurs as 
a crystalline mineral called blende, generally colored, from 
presence of iron and other impurities ; it is obtained arti- 
ficially as a white gelatinous precipitate, insoluble in acetic, 
but soluble in a mineral acid, formed when an alkaline sul- 
phide is added to a soluble zinc salt. The carbonate, Zn C03, 
an insoluble substance, occurring native as calamine: it can- 
not be prepared by precipitating a solution of zinc salt by an 
alkaline carbonate, as a quantity of oxide is precipitated along 
with the carbonate. The salts of zinc can be distinguished by 
the solubility of the oxide in excess of both potash and am- 
monia ; by the white sulphide insoluble in acetic acid, and by 
the green color which a solution of cobalt chloride imparts to 
these salts when heated before the blowpipe. 
3. Cadmium. Symbol Cd. Co7nbining Weight 112. Speci- 
fic Gravity 8'6. 
This is a comparatively rare metal, occurring in certain zinc 
ores. In its chemical relations it closely resembles zinc. It Elementary Chemistry. 
is, however, more volatile than the other metal, and therefore 
distils over first in the preparation of zinc. Cadmium is a 
white ductile metal, melting at 3150 ; it may be easily dis- 
tinguished and separated from zinc by yielding a bright yel- 
low sulphide insoluble in hydrochloric acid. The metal takes 
fire when heated in the air, forming a brown oxide, Cd O. 
The chloride and sulphate are soluble well-crystallizing salts. 
Cadmium iodide is occasionally used in photography, and the 
yellow sulphide has been employed as a pigment. 
Class V. Iron Class.—1, Manganese. 2, Iron. 3, 
Cobalt. 4, Nickel. 5, Chromium. 6, Uranium. 7, 
Indium. 
i. Manganese. Symbol Mn. Combining Weight 55, 
Specific Gravity 8'o. 
Manganese occurs in nature as an oxide, and it can be ob- 
tained, though with difficulty, in the metallic state by heating 
the oxide very strongly with charcoal. The metal is of a red- 
dish-white color; it is brittle, and hard enough to scratch 
glass. It decomposes water at the ordinary temperature with 
evolution of hydrogen ; it cannot be preserved in the air 
without undergoing oxidation, and must be kept under naph- 
tha, or in a sealed tube ; it is slightly magnetic, and, like iron, 
combines with carbon and silicon. Metallic manganese is not 
used in the arts, but an alloy of this metal and iron is now 
made on a large scale, and used in the manufacture of steel. 
Some of its oxides are used for the purpose of evolving chlo- 
rine from hydrochloric acid, and also for tinting glass a purple 
color. 
Manganese forms several well-characterized oxides: (1) 
Manganous oxide, or manganese 7nonoxide, MnO, is a basic 
body, furnishing the series of well-known manganous salts, in 
which the oxygen is replaced by its equivalent of another 
element, or of a salt ra'dical; thus, MnO, MnCb, MnS04, 
Mn2 N03 ; (2) manganic oxide, or manganese sesquioxide, 
Mn20*, which also forms salts, but of a much less stable 182 
Elementary Chemistry. 
character, and occurs in nature as the mineral braunite ; (3) 
red, or mangano-manganic oxide, Mn304, a neutral body, cor- 
responding to the magnetic oxide of iron, and occurring in 
nature as hausmannite ; (4) black oxide, or manganese dioxide, 
MnOa, a neutral substance, occurring as the ore of manganese 
in the minerals pyrolusite and varvacite ; (5) and (6) two 
compounds of manganese and oxygen which have not been 
prepared in the anhydrous state, but of which the acids cor- 
responding are known in combination as salts ; thus we 
have K2Mn04, potassium manganate, and KMn04, potassium 
permanganate. 
Manganous Oxide, MnO, is a greenish powder, obtained by 
heating the carbonate in absence of air ; it forms, with acids, 
a series of pink-colored salts, and rapidly absorbs oxygen, 
passing into a higher state of oxidation. The hydrate is 
precipitated as a white gelatinous mass, when an alkali is 
added to a solution of manganous salt; this, however, rapidly 
becomes brown, owing to absorption of oxygen. Of the 
manganous salts, the chief soluble ones are, the sulphate, 
MnS04 + 5H2O, a pink-colored crystalline salt, prepared by 
acting on the dioxide with sulphuric acid, oxygen gas being 
evolved, 
MnOs -4- H2S04 — MnS04 -4-0-1- H30 5 
the chlo7'ide, MnCU + 4 H30, is a salt obtained by crystalli- 
zation from the residues in the manufacture of chlorine from 
the dioxide and hydrochloric acid, 
Mn02 + 4 HC1 = MnCb + 2H2O -f Cl2. 
Among the insoluble manganous salts of importance are the 
sulphide, MnS, obtained as a flesh-colored precipitate by the 
addition of an alkaline sulphide to a soluble manganous salt; 
and the carbonate, MnCOa, which occurs native, crystallizing 
like ealespar in rhombohedra, and is prepared as a white 
powder by precipitating a manganous salt by an alkaline 
carbonate. 
Manganese Sesquioxide, Mna Os, exists in nature as braun- Elementary Chemistry. 
ite, and may be prepared artificially by exposing manganous 
oxide to a red heat. It forms a series of somewhat unstable 
salts, of which the manganese alum is one of the most inter- 
esting, being isomorphous with common alum, in which 
Mn2 03 is substituted for Al2Os. 
Manganese Dioxide, Mn 02, is the common black ore of 
manganese, and is termed pyrolusite by mineralogists ; it 
can be artificially formed by adding a solution of bleaching 
powder to a manganous salt. This substance yields one-third 
of its oxygen when heated to redness (see p. 11), forming the 
red oxide, 3 Mn02 = Mn304 + 02, and gives up half its oxy- 
gen when heated with sulphuric acid (see above.) It is largely 
used for the manufacture of chlorine. 
Manganic, arid Per-manganic Acids. When an oxide of 
manganese is fused with caustic alkali, a bright green mass 
is formed, which yields a dark green solution ; this contains 
potassium manganate, K2Mn04, which may be crystallized, 
and is isomorphous with the corresponding sulphate and 
chromate. If this green solution be allowed to stand, it 
slowly changes to a bright purple color, and hydrated man- 
ganic dioxide is deposited, hence its common name of mine- 
ral chamelion : it then contains a new salt in solution, viz. a 
per-manganate, KMn04, which may be obtained in the crys- 
talline state by evaporation, and is isomorphous with potas- 
sium perchlorate. The presence of a few drops of acid at 
once effects this decomposition on the green solution. 
The manganates and per-manganates readily give up a part 
of their oxygen in presence of organic matter, and they are 
now largely used as disinfectants, and known as Condy’s 
liquids, as well as being employed in the laboratory for the 
purpose of volumetric analysis. Manganese is chiefly charac- 
terized by the flesh-colored sulphide, and by the formation of 
the green sodium manganate, a most delicate reaction. 184 
Elementary Chemistry. 
LESSON XXII 
2. Iron. Symbol Fe. Combining Weight 65. Specific 
Gravity 7‘8. 
Iron is of all metals the most important to mankind. The 
uses of iron were long unknown to the human race, the age 
of iron implements being preceded by those of bronze and 
stone. Pure metallic iron exists only in very small quantity 
on the earth’s surface, almost entirely occurring in those 
peculiar structures known as meteoric stones, which possess 
an extra-terrestrial origin. 
The process of obtaining iron from its ores is a somewhat 
difficult one, and requires an amount of knowledge and skill 
which the early races of men did not possess. The iron of 
commerce exists in three different forms, exhibiting very 
different properties, and possessing different chemical con- 
stitutions : 1, wrought iron; 2, cast iron; 3, steel. 
The first is nearly pure iron, the second is a compound of 
iron with varying quantities of carbon and silicon, and the 
third a compound of iron with less carbon than that needed to 
form cast iron. The modes of manufacture of these three 
kinds of iron are essentially different, and will be best under- 
stood when the properties of the metal have been described. 
Pure iron in the form of powder may be obtained by reduc- 
ing the oxide, moderately heated in a current of hydrogen ; it 
must, however, be retained in an atmosphere of hj'drogen, as 
finely-divided iron takes fire and burns to oxide when exposed 
to the air. A button of pure iron may be prepared by expos- 
ing fine iron wire mixed with some oxide of iron to a very 
high temperature in a covered crucible, the oxide retaining 
the traces of impurity which the wire contained. Iron has a 
bright white color, and is remarkably tough, though soft, an 
iron wire two mm. in thickness not breaking until when 
weighted with 250 kilogs. The pure metal crystallizes in 
cubes ; iron which has been uniformly hammered exhibits, 
when broken, a granular and crystalline structure: this Elementary Chemistry. 
185 
structure becomes, however, fibrous when the iron is rolled 
into bars, and the more or less perfect form of the fibre deter- 
mines to a great extent the value of the metal. This fibrous 
texture of hammered bar iron undergoes a change when 
exposed to long continued vibration, the iron returning to its 
original crystalline condition; and many accidents have 
occurred in the sudden snapping of railway axles, owing to 
this change from the fibrous to the granular texture. Wrought 
iron melts at a very high temperature ; but as it becomes soft 
at a much lower point, it can be easily worked, especially as, 
when hot, it possesses the peculiar property of “ welding; ” 
that is, the power of uniting firmly when two clean surfaces of 
hot metal are hammered together. 
Iron and certain of its compounds are strongly magnetic, 
but the metal loses this power when red-hot, regaining it upon 
cooling. A solid mass of iron does not oxidize or tarnish in 
dry air, at the ordinary temperature, although iron powder 
takes fire spontaneously ; but if heated, it oxidizes with the 
production of black scales of oxide, and when more strongly 
heated in the air, or plunged into oxygen gas, it burns with 
the formation of the same black oxide. In pure water, iron 
does not lose its brilliancy; but if a trace of carbonic acid is 
present, and access of air is permitted, the iron begins at once 
to oxidize at the surface, or to rust, forming a hydrated ses- 
quioxide. Iron decomposes steam at a red heat, liberating 
hydrogen (see p. 15), and forming the black oxide produced by 
the combustion of iron in oxygen. The oxides of iron are 
four in number: (1) the monoxide, or ferrous oxide, FeO, 
from which the green or ferrous salts are derived ; (2) the 
sesqui or ferric-oxide, Fe203, yielding the yellow ferric salts ; 
(3) the magnetic, or black oxide, Fe304, which does not form 
any definite salts ; {4) ferric acid, H2Fe04, a weak acid, form- 
ing colored salts with potassium. 
Ferrous Oxide, or Protoxide of Iron, FeO. Tiiis sub- 
stance has not been prepared in the pure state, owing to the 
great readiness with which it absorbs oxygen, passing into 
the higher oxides. Hydrated ferrous oxide is thrown down 186 
Elementary Chemistry. 
as a white precipitate, when potash or soda is added to a 
soluble ferrous salt; this white precipitate can only be 
obtained in complete absence of oxygen, as it at once absorbs 
this gas, yielding a greenish-brown precipitate of a higher 
oxide. This oxide colors glass green (see p. 176), and gives 
the peculiar tint to common bottle-glass. The most impor- 
tant of the ferrous salts are— 
Ferrous Sulphate, Fe SO4 + 7 H20. This soluble salt, 
sometimes called green vitriol, is obtained by dissolving (1) 
metallic iron, or (2) ferrous sulphide, in sulphuric acid, or by 
the slow oxidation of pyrites, Fe S2. 
(1) Fe + H2SO4 = Fe S04 + H2 
(2) FeS + FUSO4 = Fe S04 + H2S. 
The solution thus obtained yields on evaporation large 
green crystals of the salt. It is largely used in the manufac- 
ture of several black dyes, and is one of the constituents of 
writing-ink. Like ferrous oxide, this salt easily takes up 
oxygen, producing a new salt called ferric sulphate. 
Ferrous Chloride, Fe Cl2. When dry hydrochloric acid gas 
is passed over hot metallic iron, ferrous chloride and hydrogen 
are formed ; the hydrated chloride is also produced when iron 
is dissolved in aqueous hydrochloric acid, green crystals being 
deposited, having the composition Fe Cl2 + 4 H20. 
Ferrous Carbonate, Fe C03. This is an insoluble com- 
pound, and occurs largely as a mineral, constituting the clay 
iron-stone ; the ore of iron from which a large proportion of 
our iron is prepared. 
Ferrous Sulphide, Fe S, an invaluable compound, formed 
by fusing equivalent quantities of sulphur and iron together, is 
employed in the laboratory for the generation of sulphuretted 
hydrogen (see p, 114). A disulphide, Fe S2, called iron 
pyrites, is found in large quantities, and is much used in the 
production of sulphuric acid (see p. 111). 
Ferric Oxide, Fe2 03. This oxide occurs native, as the 
minerals red haematite and specular iron ore, whilst, combined 
with water, it forms brown haematite. It may be readily pre- Elementary Chemistry. 
pared artificially by heating ferrous sulphate to redness ; or by 
adding solution of ammonia or caustic potash to a solution of 
a ferric salt, when the hydrated oxide falls down as a bulky 
brownish-red powder, which dissolves in acids, forming the 
ferric salts: thus, when acted upon by sulphuric a.c\d., ferric 
sulphate, Fe2 3SO-1, is produced; and by hydrochloric acid, 
ferric chloride, Fe2 Cl6. Of the ferric salts, the chloride is the 
most important; the anhydrous salt forms in brilliant red 
crystals when chlorine gas is passed over heated metallic 
iron. Solutions of the ferric salts can be reduced by various 
deoxidizing agents to the corresponding ferrous salts, whilst 
these latter, in contact with an oxidizing agent, pass into the 
ferric salts. The ferrous salts are distinguished by their light 
green color, by their solutions giving (1) a white precipitate, 
with caustic alkalies ; (2) a light blue precipitate, with potas- 
sium ferrocyanide, which rapidly becomes dark: whilst the 
ferric salts are yellow-colored, and their solutions yield (1) a 
deep reddish-brown precipitate, with the caustic alkalies ; and 
(2) a deep blue precipitate, with potassium ferrocyanide. 
Ferrous oxide and the ferrous salts are magnetic, whilst the 
ferric oxide and salts are not magnetic. 
The Magnetic, or Black Oxide, Fe3 04, occurs native, crys- 
tallyzed in cubes, and, as the mineral loadstone, it constitutes 
one of the most valued ores of iron. It is the oxide formed 
when iron is oxidized at a high temperature in the air, in oxy- 
gen, or in aqueous vapor. A corresponding sulphide, Fe3S4, 
is also magnetic. 
Ferric Acid. The potassium salt of this acid is prepared 
by fusing ferric oxide and nitre together ; the mass yields, 
with water, a purple-colored solution, and contains potas- 
sium ferrate, K2 Fe04. It is an exceedingly unstable sub- 
stance ; neither the acid H2 Fe 04, nor the oxide Fe2 06 have 
been prepared. 
Manufacture of Iron. The oldest method of manufactur- 
ing wrought iron was to reduce it at once from the ore by 
heating in a wind-furnace with charcoal or coal, and to ham- 
mer out the spongy mass of iron thus obtained. This plan 188 
Elementary Chemistry. 
can only be economically employed on a small scale, and with 
the purest forms of iron ore, and has been superseded by a 
more complicated method, applicable, however, to all kinds 
of iron ore. This consists in the formation of cast iron as 
the first product, and the subsequent separation of the carbon 
and silicon which the cast iron contains. Cast iron is manu- 
factured in England chiefly from clay iron-stone, which gen- 
erally occurs in masses, situated in the immediate neighbor- 
hood of a coal seam. The clay iron-stone (ferrous carbonate, 
with clay) is first roasted, in which operation the carbonic 
acid is driven off, and ferric oxide formed, the ore afterwards 
being thrown, together with coal and limestone, into a blast 
furnace, the construction of which is seen in Fig. 56. It has 
the shape of a double cone (A B, Fig. 56), built of strong fire- 
Fig. 56. 
brick and masonry, and is about fifty feet in height, and fif- 
teen to eighteen feet in width at the broadest part. The 
furnace is closed at the bottom, the air necessary for the 
maintenance of the combustion being supplied in a powerful 
blast, blown through pipes called tuyeres (c), whilst the mix- 
ture of fuel and ore, being cast in at the top of the furnace (d), Elementary Chemistry. 
189 
is added continually as the burning mass sinks down, and the 
molten mass is drawn off at the bottom so that one furnace 
often does not stop working for several years. At the lowest 
part of the structure is the earth (e), where the melted metal 
and fused slag collect, the former being occasionally tapped 
from the bottom of the earth, and cast into pigs in moulds 
made in the sand, whilst the lighter slag, which swims on the 
surface of the metal, runs continually out from an opening at 
the upper part of the hearth. 
The first chemical change which the roasted iron ore, or 
impure ferric oxide, undergoes in its passage from the top to 
the bottom of the furnace, is its reduction to a porous mass 
of metallic iron, by the carbonic oxide gas proceeding from 
the lower layers of burning coal ; the temperature of this 
portion of the furnace is, however, much too low to melt the 
iron, and it therefore sinks down unchanged, together with 
the clay and limestone, until it reaches a point at which the 
heat is greater. Here the second change occurs ; viz. the 
clay, sand, and other impurities of the ore unite with the 
limestone to form a fusible silicate or slag, whilst the heated 
metal coming in contact with carbon, unites at once with it to 
form cast iron, a fusible compound, which runs down to the 
bottom of the furnace. This, in passing through the hot- 
test portion of the furnace, reduces the silica, with which it 
meets, to silicon, and, combined with this, it forms cast iron. 
The properties and appearance of cast irons vary much 
with the quantity of carbon and silicon which they contain ; 
for cast iron is not a definite chemical compound of these 
elements with iron. The carbon is found in cast iron, (i) as 
scales of graphite, giving rise to mottled cast iron ; and (2) in 
combination, forming white cast iron. Sometimes sulphur 
and phosphorus are also found in cast iron, but these must 
be considered as impurities. A great saving of fuel in the 
working of blast furnaces has lately been effected by employ- 
ing the heat of combustion of the waste gases—which usually 
escape and burn at the top of the furnace—to raise the tem- 
perature of the blast of air supplying the furnace. 190 
Elementary Chemistry. 
In order to obtain wrought from cast iron, the latter must 
undergo the processes of “ refining ” and “ puddling.” These 
consist essentially in burning out the carbon, silicon, sulphur, 
and phosphorus, by exposing the heated metal to a current of 
air in a reverberatory furnace ; the melted cast iron becomes 
first covered with a coat of oxide, and gradually thickens so 
as to allow of its being rolled into large lumps or balls. 
During this process the whole of the carbon escapes as car- 
bonic oxide, and the silicon becomes oxidized to silica, which 
unites with the oxide of iron, and forms a fusible slag ; any 
phosphorus or sulphur contained in the pig iron is also 
oxidized in this process. The ball is then hammered to give 
the metal coherence, and to squeeze out the liquid slag, and 
the mass is afterwards rolled into bars or plates. 
Another interesting branch of the iron trade is the manu- 
facture of steel; this useful substance is formed when bars 
of wrought iron are heated to redness for some time in con- 
tact with charcoal: the bar is then found to have become 
fine-grained instead of fibrous, the substance is more mal- 
leable and more easily fusible than the original bar iron, and 
is found to contain carbon varying in amount from one to two 
per cent. Steel possesses several important properties, 
especially the power of becoming very hard and brittle when 
quickly cooled, which fits it for the preparation of cutting- 
tools, &c. ; these are, however, generally made of bar-steel, 
which has been previously fused and cast into ingots. 
A new and very rapid mode of preparing cast steel, which 
is both of high scientific interest and industrial importance, 
is that known as the Bessemer process. This process con- 
sists in burning out all the carbon and silicon in cast iron by 
passing a blast of atmospheric air through the molten metal, 
and then in adding such a quantity of pure cast iron to the 
wrought iron thus prepared as is necessary to give carbon 
enough to convert the whole mass into steel; the melted 
steel is then at once cast into ingots. In this way six tons of 
cast iron can at one operation be converted into steel in 
twenty minutes. The Bessemer steel is now largely manu- Elementary Chemistry. 
191 
factured for railway axles and rails, for boiler-plates, and other 
purposes, for which it is much more fitted than wrought iron, 
so that this process bids fair to revolutionize the old iron 
industry. 
•LESSON XXIII. 
3. Cobalt. Symbol Co. Combining Weight 587. Spe- 
cific Gravity 8-5. 
Cobalt is a reddish-white, very tenacious metal, which is as 
infusible as iron, and, like the latter metal, is strongly magnetic. 
It is not found native, but occurs in combination with arsenic 
and sulphur, as two distinct minerals. The metal dissolves 
slowly in sulphuric and hydrochloric acids with evolution of 
hydrogen. The cobalt compounds are distinguished for the 
brilliancy of their color ; they are employed as pigments, and 
they impart a magnificent blue tint to glass. There are two 
oxides of cobalt, the monoxide, CoO, and the sesquioxide, 
Co2 03 : the former, on solution in acids, forms the protosalts 
of cobalt, which are pink when hydrated, and blue when 
anhydrous ; whilst the sesquioxide does not form any salts. 
The monoxide, CoO, is obtained as a brown powder by care- 
fully heating the rose-colored hydrate, precipitated by potash 
in solutions of cobalt; and the sesquioxide, Co203, is pre- 
pared by adding a solution of bleaching-powder to a soluble 
protosalt. The most important salts of cobalt are the 
Chloride, Co CL, obtained by acting on the oxide, or on the 
metallic ore with hydrochloric acid ; the solution yields on 
evaporation pink crystals of the hydrated chloride, or, if 
further heated, blue crystals of the anhydrous salt. The 
cobalt, nitrate, and sulphate, are also soluble salts ; the latter 
is isomorphous with magnesium sulphate. Cobalt sulphide, 
Co S, is a black powder, insoluble in dilute acids. Cobalt can 
be easily recognized by the deep blue tint which very minute 192 
Elementary Chemistry, 
traces impart to glass, or to a borax bead, made by fusing 
borax into a colorless mass on the loop of a platinum wire. 
4. Nickel. Symbol Ni. Combining Weight 587, Specific 
Gravity 8-8. 
Nickel occurs in large quantities, combined with arsenic, 
as kupfernickel; also together with cobalt in speiss; and it is 
now prepared in considerable quantities for the manufacture 
of German silver, an alloy of nickel, zinc, and copper. Nickel 
is a white, malleable and tenacious metal; it melts at a some- 
what lower temperature than iron, and is strongly magnetic, 
but loses this property when heated to 350°. There are two 
oxides of nickel, the monoxide, Ni O, and the sesquioxide, 
Ni203: the former of these gives rise to the nickel salts, 
which possess a peculiar apple-green color. The monoxide 
is obtained by heating the nitrate or carbonate, or by precipi- 
tating a soluble nickel salt with caustic potash, and heating 
the apple-green hydrate, which is thrown down. The sesqui- 
oxide is a black powder, prepared by adding a solution of 
bleaching-powder to a soluble nickel salt. The important 
soluble nickel salts are the sulphate, NiS04 + 7H2O, crys- 
tallizing in green prisms ; Ni 2 (N03), the filtrate; and the 
chloride, NiCL. Like cobalt, nickel forms a black sulphide, 
Ni S, insoluble in dilute acids ; but the nickel salts may be 
distinguished from those of the former metal by imparting a 
reddish-yellow color to the borax bead, as well as by their 
green color. 
5. Chromium. Symbol Cr. Combining Weight S2‘5- 
Specific Gravity 6 8. 
Chromium is a substance whose compounds do not occur 
very widely distributed, or in large quantities, bat they are, 
nevertheless, much employed in the arts as pigments, many 
of them possessing a fine bright color. The chief ore of this 
metal is a compound of the oxides of chromium and iron, 
called chrome iron-stone, found in America, Sweden, and the 
Shetlands; a compound of chromium, lead, and oxygen, Elementary Chemistry. 
193 
called lead chromate, is also found in some quantity. Pure 
chromium appears to be the most infusible of all the metals, 
as it cannot be melted at a temperature sufficient to fuse and 
volatilize platinum ; it has, however, been obtained by another 
process, in the form of bright crystals belonging to the cubic 
system. Chromium unites with oxygen in four different pro- 
portions ; (l) chromous oxide, CrO ; (2) chromic sesquioxide, 
Cr2 03 ; (3) chromo-chromic oxide, Cr O Cr203 ; (4) chrome 
trioxide, Cr03. The two first of these oxides yield correspond- 
ing chlorides and salts; thus, CrO, Cr203, CrCl2,Cr2Cl8; the 
third oxide is a neutral body, corresponding to the magnetic 
oxide of iron ; and the fourth oxide forms with water an acid. 
Chromoiis oxide, CrO, is only known in the hydrated state, 
as both it and its compounds absorb oxygen with great 
avidity; the hydrate is prepared as a brown precipitate by 
adding potash to the solution of chromous chloride. Chrome 
sesquioxide, Cr203, is a perfectly stable substance, prepared 
by igniting the hydrate precipitated by adding ammonia to a 
solution of chromic chloride. Chrome trioxide, Cr03, is pre- 
pared by adding strong sulphuric acid to a saturated solution 
of potassium chromate; potassium hydric-sulphate, water, 
and chrome trioxide being formed : the latter crystallizing out 
in splendid long, ruby-red prisms. Chrome trioxide is a 
very deliquescent substance, which in solution in water has a 
strong acid reaction, and may then be termed chromic acid.\ 
neutralizing bases, and forming yellow or red-colored salts, 
called chromates. Chrome trioxide gives up a portion of its 
oxygen very readily when placed in contact with organic 
matter, being reduced to chrome sesquioxide. The most 
ready mode of preparing a solution of chromic chloride, Cr2Cl6, 
is to boil a solution of chromic acid, or a chromate with hydro- 
chloric acid and alcohol, the red or yellow solution, after a few 
minutes, being changed to a deep greenish-blue color. A 
solution of chromic sulphate, Cr23S04, may be obtained in 
like manner by substituting sulphuric for hydrochloric acid. 
This salt forms a series of alums with potassium and ammo- 
nium sulphate, which have a deep purple tint, and are isomor- 194 
Elementary Chemistry. 
phous with common alum. The anhydrous chromic chloride 
is obtained as a sublimate, in beautiful violet crystals, by pass- 
ing a stream of chlorine gas over a red-hot mixture of chrome 
sesquioxide and charcoal. If any salt of the chrome sesqui- 
oxide is fused with an alkaline carbonate, it becomes oxidized, 
and an alkaline chromate is formed, and this is the mode by 
which all the chromium compounds are prepared from chrome 
iron ore. Three potassium chromates are known : (i) netdral 
potassium chromate, K2Cr 04; (2) potassium anhydro-chro- 
mate, or bichromate, KiCr04,Cr03 ;* and (3) potassium dian- 
hydrochromate, or terchromate, The first of 
these salts is deposited in yellow crystals, which are isomor- 
phous with potassium sulphate, when chrome iron-stone is 
heated with caustic potash ; the second crystallizes in large 
red prisms on adding to a solution of the neutral chromate 
sulphuric acid sufficient to combine with half the base ; this 
salt is manufactured on a large scale, and serves for the pre- 
paration of the various chrome pigments ; the third potassium 
chromate is an unimportant salt, obtained by crystallizing the 
second compound with an excess of chromic trioxide. 
The chief of the insoluble chromates are lead chromate, 
Pb Cr O4, or chrome yellow, obtained by precipitating potas- 
sium chromate by a soluble lead salt, and largely used for 
dyeing and other purposes in the arts ; silver chromate, 
AgoCrOi, a characteristic deep-red colored precipitate; and 
barium chromate, BaCr04, also a yellow insoluble powder, 
A volatile compound intermediate between chrome trioxide 
and chromic chloride is known, termed chlorochrotnic oxide, 
Cr 02 Cl2 ; this substance is obtained in the form of a dark 
red, strongly fuming liquid, when a soluble chromate is distilled 
with sulphuric acid and common salt; the vapor density of 
chlorochromic oxide is 777 (when H = 1), the specific gravity 
of the liquid 17, and its boiling point 1210. It maybe re- 
garded as chrome trioxide in which one atom of oxygen has 
been replaced by its equivalent of chlorine, and is analogous 
to chloro-sulphuric acid and to many organic compounds. 
* A salt analogous to borax (p. 125). Elementary Chemistry. 
The presence of chromium and its compounds can be easily- 
detected by the formation of soluble yellow-colored alkaline 
salts, yielding insoluble lead and silver compounds, and ca- 
pable of easy reduction to green solutions in presence of 
organic matter. Chromic oxide imparts to glass or borax a 
fine deep green color. 
6. Uranium. Symbol U. Combining Weight 120. Spe- 
cific Gravity 18‘4. 
Uranium is a metal which occurs but sparingly in nature, 
existing combined in two somewhat rare minerals, pitchblende 
and uranite. The metal is of a steel-white color, and it does 
not oxidize in dry air at ordinary temperatures, but when 
strongly heated it burns brilliantly. There are two oxides 
which form salts, viz. uranous oxide, UO, and uranic oxide, 
U2Os; the uranous salts are green, whilst the uranic com- 
pounds are yellow ; and these latter solutions give yellow 
precipitates, with an alkali, in which the uranic oxide acts as 
an acid, forming a uranate of the base. The sulphide is an 
insoluble salt of a yellowish-brown color. The chief applica- 
tion of uranium compounds is for the purpose of glass-stain- 
ing ; the uranous oxide imparts a fine black, and the uranic 
oxide a beautiful yellow, to glass; uranium compounds are 
also now used in photography. 
7. Indium. Symbol In. Combining Weight 74-0 
A metal lately discovered by means of spectrum analysis in 
certain zinc ores. Its compounds impart a blue color to 
flame, and its spectrum is characterised by a fine indigo- 
colored line. The properties of indium and its compounds 
have as yet not been fully examined, but in its general be- 
havior it resembles the metals of the foregoing group. 
195 
Class VI. 1, Tin. 2, Titanium. 
I. Tin. Symbol Sn. (Stannum). Combining Weight 118. 
Specific Gravity 7-3. 196 
Elementary Chemistry. 
The ores of tin—although this metal has been known from 
very early times—occur in but few localities, and the metallic 
tin is not found in nature. The chief European sources of 
tin are the Cornish mines, where it is found as tin dioxide or 
tin-stone. It is in all probability from these mines that the 
Phoenicians and Romans obtained all the tin which they em- 
ployed in the manufacture of bronze. Tin-stone is also met 
with in Malacca, and Borneo, and Mexico. In order to pre- 
pare the metal, the tin-stone is crushed and washed to remove 
mechanically the lighter portions of rock with which it is 
mixed, and the purified ore is then placed in a reverberatory 
furnace with anthracite or charcoal and a small quantity of 
lime ; the oxide is thus reduced, and the liquid metal, to- 
gether with the slag, consisting of silicate of lime, falls to the 
lower part of the furnace. The blocks of tin, still impure, are 
then refined by gradually melting out the pure tin, leaving an 
impure alloy behind. English tin generally contains traces 
of arsenic, copper, and other metals ; that imported from 
Banca is nearly chemically pure. 
Tin possesses a white color resembling that of silver ; it is 
soft, malleable and ductile, but possesses little tenacity, a wire 
two mms. in diameter breaking with a weight of sixteen kilos. 
When bent, pure tin emits a peculiar crackling sound; tin 
melts at 2350, and is not sensibly volatile. Tin does not lose 
its lustre on exposure to the air, whether dry or moist, at or- 
dinary temperature, but if strongly heated it takes fire, and a 
white powder of stannic oxide (sometimes termed putty 
powder) is formed. Hydrochloric acid dissolves tin with the 
evolution of hydrogen and the formation of stannous chlo- 
ride ; nitric acid also attacks the metal with great energy, 
nitrous fumes being given off and stannic oxide being left 
as a white powder. There are two well-marked oxides of tin. 
Stannous oxide, Sn O. This is a black powder prepared 
by heating the stannous hydrate in an atmosphere of carbonic 
acid ; it rapidly absorbs oxygen from the air, passing into 
stannic oxide. The hydrate falls as a white powder when a 
solution of a stannous salt is added to an alkaline carbonate. Elementary Chemistry. 
197 
The stannous chloride, SnCl2, is obtained by dissolving tin in 
hydrochloric acid, and separates out in needle-shaped crystals, 
SnCl2 + 2H20, when the solution is concentrated. Stannous 
chloride is termed “ tin salts ” in commerce ; it is largely manu- 
factured for the calico printer and dyer, who use it as a 
“ mordant.” 
Stannic oxide, Sn 02, occurs native as tin-stone, and it can 
be prepared artificially in two conditions, possessing totally 
different properties. If tin be oxidized by nitric acid, stannic 
oxide is produced as a white powder insoluble in acids ; if, 
on the other hand, to a solution of stannic chloride an alkali 
be added, a white precipitate is formed of stannic oxide, which 
is readily soluble in acids. Both of these varieties of hydrated 
stannic oxide form salts, the insoluble compound having 
been termed metastannic, and the soluble compound stannic 
acid. Sodium stannate, Na2 Sn 03, 4 H2 O, formed by boil- 
ing stannic oxide with soda, is largely used in calico printing 
as a mordant, and then termed “ tin prepare liquor.” Stannic 
chloride, Sn CU, is obtained by passing chlorine gas over 
metallic tin; it is a colorless liquid, boiling at I20°C, and 
having a vapor density of g‘2. It fumes strongly in the air, 
and forms a crystalline hydrate, when a small quantity of water 
is added, which easily dissolves in an excess. Stannic chloride 
is also used by dyers, and is prepared for this purpose by 
dissolving tin in cold nitro-hydrochloric acid. Of the sulphides 
of tin, SnS, stannous sulphide, and Sn S2, stannic sulphide, 
are the most important; the former is blackish-gray, and the 
latter a bright yellow crystalline powder known as mosaic 
gold, soluble in alkaline sulphides. 
Tin can easily be distinguished in solution by the formation 
of a splendid purple color called purple of cassius, formed 
when gold chloride is added to a dilute solution of stannous 
chloride. Tin is also easily reduced before the blowpipe in 
the form of white malleable beads. Tin is largely used in 
the arts for covering and thus protecting iron plates, or for “ tin- 
plating,” and also for preparing several valuable alloys, as pew- 
ter, Britannia metal, plumbers’ solder, bronze, bell-metal, &c. Elementary Chemistry. 
198 
Titanium is a rare metal, resembiing tin in its chemical 
properties. It is found in combination with iron in the 
mineral rutile. The oxides of titanium correspond to those 
of tin ; viz., titanous and titanic oxides, Ti O, and Ti 02. 
Titanium and its compounds are not used in the arts. 
Niobium and Tantalum are two extremely rare metals, 
whose properties are as yet but imperfectly known. 
2. Titanium. Symbol Ti. Combining Weight 50, 
Class VII. Tungsten Class. 
1. Molybdenum. Symbol Mo. Cotnbining Weight 96, 
The chief ore of this metal is molybdic disulphide, a mineral 
in appearance resembling graphite. The metal is a gray 
substance, which oxidizes on heating in the air to molybdic 
trioxide, Mo 03, a yellow powder which acts as an acid, form- 
ing with bases salts called molybdates. The compounds of 
molybdenum do not occur frequently, and are not used in the 
arts. 
2. Vanadium. Symbol V. Combining Weight 137. 
This is a very rare metal, its compounds occur in small 
quantity in certain iron ores, and also in combination as 
vanadiate of lead. It forms an interesting oxide, termed 
Vanadic Trioxide, V 03. 
3. Tungsten. Symbol W. (Wolfram). Combining 
Weight 184. 
This metal occurs in tolerably large quantities combined 
with ferrous oxide in the mineral wolfram, and also with lime 
as scheelite. The metal has only been obtained as a grayish- 
black powder, having a specific gravity of 17-4. Tungsten 
is employed occasionally in the arts—the addition of a small 
quantity imparts a great degree of hardness and other valuable 
qualities to steel. Two oxides of tungsten are known,— 
Tungstic Dioxide, W 02, and Tungstic Trioxide, WO3. The 
former of these is obtained as a brown powder by heating the Elementary Chemistry. 
199 
trioxide in an atmosphere of hydrogen ; the latter, sometimes 
called tungstic acid, is obtained as an insoluble yellow powder 
by heating the native calcium tungstate with nitric acid. 
Tungsten trioxide forms a variety of somewhat complicated 
salts. The sodium compound is soluble, and has been used 
to add to the starch employed to stiffen light fabrics, the 
tungstate rendering the fabric uninflammable. 
LESSON XXIV. 
Class VIII.—1, Arsenic. 2, Antimony. 3, Bismuth. 
1. Arsenic. The properties of this element and its com- 
pounds have been already considered (see p. 133). 
2. Antimony. Symbol Sb (Stibium). Combining Weight 
122. Specific Gravity 671. 
Metallic antimony occurs native, but its chief ore is the tri- 
sulphide. The metal is easily reduced by heating the sul- 
phide with about half its weight of metallic iron, when ferrous 
sulphide and metallic antimony are formed. Antimony may 
also be reduced by mixing the ore with coal and heating in a 
reverberatory furnace. Antimony is a bright bluish-white 
colored metal, crystallizing in rhombohedra, isomorphous with 
arsenic. It is very brittle, and can be powdered in a mortar ; 
it melts at 450°, and may be distilled at a white heat in an 
atmosphere of hydrogen. Antimony undergoes no alteration 
in the air at ordinary temperatures, but rapidly oxidizes if 
exposed to air when melted, and, if heated more strongly, it 
takes fire and burns with a white flame, giving off dense white 
fumes of antimonic trioxide. Antimony is not attacked either 
by dilute hydrochloric or sulphuric acids ; nitric acid attacks 
the metal, converting it into white insoluble antimonic oxide. 
Nitro-hydrochloric acid dissolves antimony easily. The alloys 200 
Elementary Chemistry. 
of antimony are largely used in the arts ; of these, type metal 
(an alloy of lead and antimony) is the most important: it con- 
tains 17 to 20 per cent, of the latter metal. The two impor- 
tant oxides of antimony, (1) antimonious oxide, or trioxide, 
Sb3 O3, (2) antimonic oxide, Sb3 06 (sometimes called anti- 
monic acid), correspond to those of arsenic (see p. 133). A 
third oxide exists unknown in the arsenic series ; this is an 
intermediate gray oxide, having the composition Sb3 03 Sb3 
06. 
Antimonious Oxide, Sb3 O3. This oxide gives rise to the 
important series of salts of antimony used in medicine ; it is 
obtained in crystalline needles, which are isomorphous with 
the rare form of arsenious oxide (see p, 134). Antimonious 
oxide has also been observed to crystallize in octohedra ; 
hence these two oxides are said to be isodimorphous. The 
best mode of preparing the pure oxide is by decomposing 
antimonic chloride with an alkaline carbonate, when the oxide 
is precipitated as a white powder: thus, 2 Sb Cl3 + 3 Na3 
COs = Sb3 Os + 6 Na Cl + 3 C03. Antimonious oxide dis- 
solves, when boiled with a solution of cream of tartar (hydric 
potassium tartrate), and on concentration the solution deposits 
crystals of tartar emetic (potassium antimony tartrate); anti- 
monious oxide also dissolves in hydrochloric acid, yielding a 
solution of the trichloride, but this is rendered turbid by addi- 
tion of water. 
Antimonic Oxide, Sb3 05 (sometimes called Antimonic 
Acid), obtained by acting on antimony with strong nitric acid, 
or by decomposing the penta-chloride of antimony with water. 
It is a light straw-colored powder, which loses oxygen at a 
red heat, and is converted into the intermediate oxide Sb3 
03 Sb3 Os. Antimonic oxide forms salts with the alkalies 
called Antimoniates, from which antimonic acid, Sb3 08 H3, 
can be separated as a white powder. The oxides prepared by 
the two methods above given are found to possess different 
properties as regards their power of uniting with bases. That 
prepared with nitric acid yields monobasic salts, whilst that 
obtained from the penta-chloride yields dibasic salts; to the Elementary Chemistry. 
201 
first class of salts the name Antimoniates, and to the second 
that of Metantimoniates has been given. The gray interme- 
diate oxide, Sb2 03 Sb2 06, is obtained by heating the metal 
in the air until no further change occurs. 
Finely-powdered metallic antimony takes fire spontaneously 
when thrown into chlorine gas with formation of the chlorides. 
There are two chlorides of antimony ; antitnony tri-chloride, 
Sb Cl3, is obtained as a buttery mass by passing chlorine gas 
over an excess of metallic antimony, or by dissolving the 
metal or sulphide in hydrochloric acid to which a little nitric 
has been added: on distilling the liquid thus obtained the 
trichloride volatilizes, and, on cooling, solidifies to a mass of 
white crystals. Thzpenta-chloride, Sb CL, is a mobile strongly- 
fuming liquid, obtained by passing an excess of chlorine over 
the trichoride or the metal. The sulphides of antimony, Sb2 
S3, and Sb2 S6, correspond to the oxides, and, like the oxides, 
are capable of uniting with the alkaline sulphides to form 
a class of soluble salts. 
Like arsenic, antimony unites with hydrogen to form a gas- 
eous compound, antimoniuretted hydrogen, Sb H3, analogous 
to As H3, arseniuretted hydrogen. This gas is evolved, 
together with hydrogen, when an antimony salt is brought in 
contact with zinc and dilute acid. Like the corresponding 
arsenic compound, it burns with a bluish flame, evolving a 
white-colored antimonious oxide, and is decomposed at a red 
heat with deposition of metallic antimony. The detection and 
separation of arsenic and antimony is a subject of much impor- 
tance in medical jurisprudence, as both substances exhibit 
poisonous characters, and closely resemble one another in 
their reactions ; still, with care it is easy to discriminate 
between these two metals, and to detect with certainty a very 
minute quantity of either when present in the body of an 
animal. 
3. Bismuth. Symbol Bi. Combining Weight 2io. Specific 
Gravity g'8. 
This metal is found in small quantities in the native state, 202 
Elementary Chemistry. 
but occurs more often as a sulphide ; it is easily reduced to 
the metallic state, and then exhibits a pinkish-white color. It 
crystallizes in large rhombohedra which can scarcely be dis- 
tinguished from cubes ; it melts at 264°, and is volatilized at 
a white heat. Bismuth does not oxidize in dry air at the 
ordinary temperature, but if heated strongly it burns with a 
blue flame, forming an oxide ; it also takes fire when thrown 
into chlorine gas. Bismuth dissolves easily in nitric acid. 
The metal is chiefly used as an ingredient of fusible metal; 
its compounds are also used in medicine, and as pigments. 
Two oxides of bismuth are known, bismuthous oxide, Bi203, 
and bismuthic oxide, Bi2 Os. The first of these is a pale yel- 
low powder, formed when the metal is roasted in the air; the 
second oxide is obtained by dissolving the first in potash and 
precipitating the bismuthic oxide by nitric acid and heating : 
it is a reddish-brown powder. Like the corresponding anti- 
mony compound, bismuthic oxide forms with the alkalies solu- 
ble salts. The nitrate, Bi 3 N03 5H2 O, is the most impor- 
tant soluble salt of bismuth; the sulphide, Bi2S3, is a black 
insoluble compound; the trichloride, BiCl3, is obtained by 
heating the metal in chlorine. One of the most striking pecu- 
liarities of the bismuth compounds is, that solutions of the 
salts become milky on the addition of water, owing to the for- 
mation of insoluble basic compounds. Metallic bismuth is 
easily reduced from its compounds, before the blowpipe, as a 
brittle bead. 
Class IX.—Lead Class, i, Lead. 2, Thallium. 
I. Lead. Symbol Pb {plumbum). Combining Weight 
207. Specific Gravity IP3. 
Lead does not occur free in nature; all the lead of com- 
merce is obtained from galena, or lead sulphide. The mode 
of reducing lead from this ore is a very simple one : the galena 
is roasted in a reverberatory furnace with the addition of a 
small quantity of lime to form a fusible slag with any silicious 
mineral matter present in the ore. By the action of the air a 
portion of the sulphide is oxidized to sulphate, whilst ia Elementary Chemistry. 
203 
another portion the sulphur burns off as sulphuric dioxide, 
and lead oxide is left behind ; after the lapse of a certain time 
the air is excluded and the heat of the furnace raised—the 
lead sulphate and oxide formed both decompose the remain- 
ing sulphide, giving off sulphuric dioxide and leaving metallic 
lead behind, thus : 
(1) Pb S04 + Pb S = 2 Pb + 2 S02. 
(2) 2 Pb O + Pb S = 3 Pb + S02. 
Galena almost always contains small quantities of silver, 
which is extracted by a process described on p. 213, Lead 
is a bluish-white-colored metal, and so soft that it may be 
scratched with the nail ; it may be drawn out to wire, or ham- 
mered into plate, but possesses little tenacity or elasticity, 
and a wire 2 mms. in diameter breaks with a load of 2 kilos. 
Lead melts at 3340, and at a higher temperature volatilizes, 
though not in quantity sufficient to enable it to be distilled. 
The bright surface of the metal remains permanently in dry 
air, but it soon becomes tarnished in moist air, owing to the 
formation of a film of oxide ; and this oxidation proceeds 
rapidly in presence of a small quantity of weak acid such as 
carbonic or acetic. In pure water freed from air lead also pre- 
serves its lustre, but if air be present lead-oxide is formed, 
and this dissolving slightly in the water a fresh portion of 
metal is exposed for oxidation. This solvent action of water 
upon lead is a matter of much importance, owing to the com- 
mon use of lead water-pipes, and the peculiarly poisonous 
action of lead compounds upon the system when taken even 
in minute quantities for a length of time. The small quantity 
of certain salts contained in all spring and river waters exerts 
an important influence on the action of lead ; thus waters 
containing nitrates or chlorides are liable to contamination 
with lead, whilst those hard waters containing sulphates or 
carbonates may generally be brought into contact with lead 
without danger, as a thin deposit of sulphate or carbonate is 
formed, which preserves the metal from further action. If 
the water contains much free carbonic acid it should not be 204 
Elementary Chemistry. 
allowed to come into contact with lead, as the carbonate dis- 
solves in water containing this substance. The presence of 
lead in water may easily be demonstrated by passing a cur- 
rent of sulphuretted hydrogen through a deep column of the 
acidified water, and noticing whether the liquid becomes 
tinged of a brown color, owing to the formation of lead sul- 
phide. Three compounds of lead and oxygen are known. 
I. Litharge, ox Lead Monoxide, Pb O, a straw-colored pow- 
der, obtained by heating lead in a current of air ; it fuses at a 
red heat, forming scaly crystals termed Litharge. Lead 
oxide is soluble in caustic potash, and is deposited from a hot 
solution in the form of rhombic prisms. This oxide forms 
with acids the important series of lead salts, which are gene- 
rally colorless, and of which the soluble ones act as violent 
poisons. Lead oxide combines with silica to form an easily 
fusible silicate, or glass ; thus earthen crucibles in which the 
oxide is fused are rapidly attacked. A white hydrated oxide 
is obtained by precipitating a soluble salt of lead by caustic 
potash, and this if heated yields the oxide. 2. Lead Dioxide, 
or puce-colored oxide, Pb 02. This oxide is a brown powder 
obtained by passing chlorine through the hydrated oxide, or 
by digesting red lead with nitric acid. Lead dioxide does not 
form salts with acids. When heated it yields half its oxygen, 
and acted upon with warm hydrochloric acid, chlorine is 
evolved, and lead chloride is formed. 
3. Red Oxide, or Red Lead, a compound of the two last 
oxides, having the composition 2 Pb O Pb 02. It is obtained 
by exposing massicot to the air at a moderate red heat, oxy- 
gen being absorbed. Red lead is chiefly used in glass-making 
{see p. 176). When treated with dilute nitric acid the lead 
oxide dissolves, forming soluble lead nitrate, leaving the puce- 
colored oxide behind. 
Of the soluble salts of lead the nitrate, Pb 2NO3, is the 
most important. This compound is obtained by dissolving 
the oxide, the carbonate, or metallic lead in warm nitric acid ; 
it crystallizes in octohedra, and dissolves in eight parts of 
cold water, and when heated strongly it yields red fumes of Elementary Chemistry. 
205 
N 02 (see p. 61). Lead acetate, or sugar of lead’ is also a 
soluble salt, which will be described under Acetic Acid. Al- 
most all the other lead salts are insoluble in water. Lead 
Carbonate, or White Lead, Pb C03, is a substance much used 
in the arts as a paint, and manufactured on a large scale. 
The salt may be obtained in the pure state by precipitating a 
cold solution of the nitrate with an alkaline carbonate, when 
it falls down as a white powder. For preparing the salt in 
quantity two plans are employed—the one similar in principle 
to that described for the pure salt; and the second an old 
and interesting process, known as the Dutch method. In this 
process thin sheets of lead are rolled into a coil, and each 
coil placed in an earthen pot containing a small quantity of 
crude vinegar (acetic acid) ; several hundred of these jars and 
coils are packed on a floor in a bed of stable manure or spent 
tanbark, and then covered with boards, whilst a second layer 
of pots similarly charged is placed above, and this is con- 
tinued until the building is filled. After remaining thus for 
several weeks, the coils are taken out, when the greater part 
of the lead is found to be converted into white carbonate. It 
appears that, to begin with, a lead acetate is formed, and that 
the acetic acid is gradually driven out from its combination 
by the carbonic acid evolved from the putrefying organic 
matter, and thus enabled to unite with another portion of the 
lead lying underneath that which was first attacked. 
Lead sulphide, ox galena, Pb S, is found native, and consti- 
tutes the chief ore of the metal. It is prepared as a black 
precipitate by passing sulphuretted hydrogen gas through a 
solution of a lead salt. Galena crystallizes in cubes and oc- 
tohedra, and possesses a bright bluish-white metallic lustre ; 
lead sulphate, Pb SO4, is a white insoluble salt, which is 
found native, and is prepared artificially by adding sulphuric 
acid to a soluble lead salt; lead chloride, PbCl2, prepared by 
adding hydrochloric acid to a strong solution of lead nitrate, 
when a crystalline precipitate of lead chloride is formed. It 
dissolves in about thirty parts of boiling water, separating 
out in shining needles on cooling ; lead iodide is precipitated 20 6 
Elementary Chemistry. 
in the form of splendid yellow spangles, when hot solutions 
of potassium iodide and lead nitrate are mixed and allowed 
to cool; lead chro?nate is a yellow insoluble salt. Lead can 
easily be recognized,—1st, by the black sulphide, soluble in 
dilute nitric acid ; 2dly, by the white insoluble sulphate ; 3dly, 
by the yellow iodide and chromate ; and 4-thly, by the easy 
reduction of the metal in the form of a malleable bead 
when any of the salts are heated before the blowpipe with a 
reducing agent. 
2. Thallium. Symbol TI. Combining Weight 204. Spe~ 
cific Gravity 1 1-85. 
Thallium was discovered in 1861 by Mr. Crookes, by means 
of spectrum analysis, in the deposit in the flue of a pyrites 
burner (see p. 110), The presence of this new metal is indi- 
cated by the occurrence of a splendid green line in the spec- 
trum. Metallic thallium closely resembles lead in its physical 
properties ; the freshly cut surface has a bluish-white lustre, 
which rapidly tarnishes ; it is so soft that it receives impres- 
sions of the nail, and can be easily drawn into wire ; it melts 
below a red heat. It is found to occur in many specimens of 
iron pyrites, and appears to take the place of arsenic, which 
is a common impurity of this mineral. Metallic thallium 
undergoes gradual oxidation, so that it is best preserved in 
water ; when strongly heated in oxygen, it takes fire, and 
burns with a bright green flame. Thallium dissolves easily in 
nitric and sulphuric acids with evolution of hydrogen, but 
more slowly in hydrochloric acid, owing to the insolubility 
of the chloride. Two oxides of this metal are well charac- 
terized, Thallous oxide, Tl2 O, and Thallic sesqui-oxide, 
Tl2 03. Thallous oxide corresponds in composition, and 
somewhat resembles in properties, the alkali potash, K20, as 
it is soluble in water, yielding an alkaline caustic solution, 
which absorbs carbonic acid from the air, and forming a well- 
defined series of salts. Of these the sulphate, Tla S04, and 
the chloride, Tl Cl, are the most important. The sulphate is 
a soluble salt, crystallizing in six-sided prisms, and furnishing Elementary Chemistry. 
20 7 
octohedral crystals of an alum with aluminium sulphate; 
whilst the chloride is only slightly soluble in water, in this 
respect more nearly resembling the corresponding lead salt. 
Thallium carbonate is also a soluble salt, requiring about 
twenty-five parts of cold water for solution. 'The sulphide, 
TUS, is an insoluble black powder, precipitated when an al- 
kaline sulphide is added to any soluble thallium compound. 
The soluble thallium salts are colorless, and act as strong 
poisons. The metal is precipitated in a pulverulent form, 
when a piece of zinc is introduced into its solutions. It will 
be seen that the properties of thallium are intermediate 
between those of lead and the alkalies. Thallium is mona- 
tomic, 204 parts of this metal replacing one part of hydrogen. 
LESSON XXV. 
Class X. Silver Class, i, Copper. 2, Mercury. 
3, Silver. 
I. Copper. Symbol Cu. Combining Weight 63*5. Specific 
Gravity 8-93. 
Copper 5s an important metal, largely used in the arts, and 
has been known from very early times, as it occurs native in 
the metallic stata, and is moreover easily reduced from its 
ores. Metallic copper is found in considerable quantity in 
North America and other localities, crystallizing in cubic and 
octohedral forms, but the chief sources of copper are the fol- 
lowing ores: (1) A compound of copper, sulphur, and iron, 
known as copper pyrites, Cu .S + Fe2 S3. (2) The cuprous 
sulphide, Cu2 S. (3) The carbonate or malachite ; and (4) 
The red or cuprous oxide, Cu2 O. The Cornish mines yield 
large quantities of copper, whilst much ore is furnished by 
Chili and South Australia. Pure metallic copper can be 
obtained by reducing the oxide in a current of hydrogen gas, Elementary Chemistry. 
208 
or by the electrolytic decomposition of a salt of copper. The 
process for obtaining copper on a large scale from the carbo- 
nate or oxide is a very simple one, viz., merely reducing these 
ores together with carbon and some silica in a wind furnace/ 
The reduction of the metal is more difficult when the com- 
moner ore, copper pyrites, is employed. In this case the ore 
is repeatedly roasted, in order partially to convert the cuprous 
sulphide into oxide, and the roasted ore melted in a rever- 
beratory furnace with the addition of sand or silicious slag; 
in this operation the cuprous oxide becomes converted into 
the corresponding sulphide, whilst the iron oxidizes and unites 
with the silica to form a light and fusible slag. The impure 
cuprous sulphide fuses and sinks to the lower portion of the 
furnace, forming the “ mat ” or coarse metal; and by repeat- 
ing this operation, a pure cuprous sulphide or “ fine metal ” is 
obtained. In order to prepare the metallic copper free from 
sulphur, this fine metal is roasted, and afterwards fused in 
contact with the air. During the first part of the operation a 
portion of the sulphur is burnt off, cupric oxide being formed, 
and in the later stages of the process this oxide acts upon the 
remaining quantity of sulphide, forming sulphuric dioxide, and 
metallic copper, Cu2 S + 2 Cu O = S02 + 4 Cu. In order 
to get rid of the last traces of oxide, the molten copper is 
“ poled ” or stirred up with a piece of green wood. 
Metallic copper possesses a peculiar deep red color, which 
is best seen when a ray of light is several times reflected from 
a bright surface of the metal; it is very malleable and ductile, 
and possesses great tenacity, a wire of two mms. in diameter 
supporting a weight of 140 kilos. ; it melts at a red heat, and 
is slightly volatile at a white heat, communicating a green tint 
to a flame of hydrogen gas, which is passed over it, and it is 
one of the best conductors of heat and electricity. Copper 
does not oxidize either in pure dry or moist air at ordinary 
temperatures, but if heated to redness in the air, it rapidly 
oxidizes to scales of copper oxide. Steam is not decomposed 
by metallic copper at a red heat. Finely divided copper dis- 
solves in hydrochloric acid with evolution of hydrogen ; when Elementary Chemistry. 
209 
heated with strong sulphuric acid, sulphurous dioxide (p. 106) 
is evolved, and copper sulphate formed ; and when acted upon 
with nitric acid, copper nitrate is produced, and nitric oxide 
(p. 59) liberated. 
Many of the copper alloys are of importance ; brass is an 
alloy containing about two-thirds of copper and one-third of 
zinc, it is harder than copper and can be more easily worked ; 
the addition of one to two per cent, of lead improves the 
quality of brass for most purposes. The yellow, or muntz 
metal, used for the sheathing of ships, contains sixty per cent, 
of copper. Bronze, gun-metal, bell-metal, and speculum-metal 
are other alloys of copper and tin in varying quantities. They 
are all remarkable for the property of being hard and brittle 
when slowly cooled, but of becoming soft and malleable if they 
are cooled suddenly when red-hot by dipping into cold water. 
Oxides of Copper. There are two well-defined oxides ; 
cuprous oxide, Cu2 O, and cupric oxide, Cu O. 
Cuprous Oxide, or Red Oxide, Cu2 O, occurs native in 
ruby-red octohedral crystals ; it is artificially prepared by 
heating equivalent quantities of cupric oxide and copper fi- 
lings, or by boiling a solution of copper sulphate and sugar, to 
which excess of caustic potash has been added: the sugar 
reduces the copper salt, and cuprous oxide is precipitated as 
a bright red powder. Cuprous oxide imparts to glass a 
splendid ruby-red color ; it forms colorless salts with acids 
which rapidly absorb oxygen from the air, and pass into the 
corresponding cupric compounds. The most important of 
these salts is cuprous chloride, Cu Cl, a white solid substance 
obtained by dissolving a mixture of cupric oxide and metallic 
copper in hydrochloric acid : the solution of cuprous chloride 
possesses the remarkable property of absorbing carbonic 
oxide gas. 
Cupric, or Black Oxide, Cu O. This oxide is formed when 
copper is heated in the air, or when cupric nitrate is heated 
to redness ; it yields the blue and green cupric salts, and it is 
largely used in the laboratory as a means of giving oxygen for 
the combustion of organic substances (see p. 236). Hydrated 210 
Elementary Chemistry. 
cupric oxide is obtained as a light blue precipitate when 
caustic alkali is added to a cupric salt; when this is heated to 
ioo° it loses its water, and the anhydrous oxide falls as a 
brown powder. Cupric oxide is soluble in acids, furnishing a 
series of well crystallizing salts ; of these the most important 
soluble compounds are: (i) copper sulphate, Cu S0« + sHa O. 
This salt is sometimes known as blue vitriol, and is largely 
manufactured by dissolving copper oxide (copper scales) in 
sulphuric acid. It crystallizes in large blue crystals belonging 
to the triclittic system (Fig. 51) ; when heated to redness, it 
loses all its water of crystallization, and forms a white powder, 
which again at a higher temperature decomposes, leaving 
copper oxide. Copper sulphate is employed in calico print- 
ing, and in the manufacture of Scheele’s green, and Brunswick 
green, and other copper pigments. The sulphate and the 
other copper salts give, with excess of ammonia, a deep-blue 
colored solution, forming a remarkable compound, capable of 
crystallizing; the production of this blue color may be used 
as a test of the presence of copper. (2) Copper nitrate, Cu 
2 (NOs) 6 (Ha0), a very soluble salt, crystallizing in large blue 
prisms obtained by dissolving copper in nitric acid. (3) Cop~ 
per chloride, Cu Cl2 + 2 H20, formed when copper is brought 
into chlorine gas, or when copper oxide is dissolved in hydro- 
chloric acid ; it forms green needle-shaped crystals soluble in 
water and alcohol. The alcoholic solution burns with a 
characteristic green flame. The insoluble copper salts are : 
(1) the sulphide, Cu S, obtained as a black precipitate, when 
sulphuretted hydrogen gas is passed through an acidified 
solution of a copper salt; (2) the carbonate, which, however, 
is not known in the pure state, as the green precipitate 
obtained by adding a solution of an alkaline carbonate to a 
copper salt, always contains hydrated oxide; the mineral 
malachite also possesses a similar composition ; (3) copper 
arsenite, or Scheele’s green, is a bright green powder used 
as a pigment, and obtained by mixing solutions of sodium 
arsenite with copper sulphate. The copper salts act as pow- 
erful poisons, and they may be detected—(1) by the black Elementary Chemistry. 
211 
insoluble sulphide ; (2) by the blue hydrate turning black on 
heating ; (3) by the deep blue coloration with ammonia ; (4) 
by the deposition of red metallic copper upon a bright surface 
of iron placed in the solution. 
2. Mercury. Symbol Hg (Hydrargyrum). Combining 
Weight 200. Specific Gravity at o° 13 596. Density 100.* 
The chief ore of mercury is the sulphide, or cimiabar, 
which occurs at Almaden in Spain, at Idria in Illyria, in Cali- 
fornia, and also in China and Japan. The metal is easily 
obtained by roasting the ore, when the sulphur burns off as 
the dioxide, and the metal volatilizes, and its vapor is con- 
densed in earthen pipes. Mercury is the only metal liquid at 
the ordinary temperature ; it freezes at -40°, crystallizing in 
octohedra; in the solid state it is malleable and possesses a 
density of 144.. It boils at 350° (measured by the air ther- 
mometer), and gives off a slight amount of vapor at the 
ordinary temperature. The specific gravity of its vapor (air 
= 1) is 6 976. Mercury when pure does not tarnish in moist 
or dry air, but when heated above 300° it slowly absorbs 
oxygen, passsing into the red oxide ; and it combines directly 
with chlorine, bromine, iodine, and sulphur. Hydrochloric 
acid does not attack mercury; sulphuric acid, on heating, 
forms sulphuric dioxide (p. 105) and mercuric sulphate; and 
nitric acid evolves nitric oxide and forms mercuric nitrate. 
Mercury is largely used in the process of extracting gold and 
silver from their ores (p. 213), and in the arts, for silvering 
mirrors, and other purposes. Mercury is deposited from its 
solutions upon metallic iron or copper, in the form of a 
gray powder, which becomes bright on burnishing. Mercury 
and its salts act as valuable medicines. 
Two oxides of mercury are known : the black or mercurous 
oxide, Hg2 O, and the red or mercuric oxide, Hg O. Mer- 
curous oxide is best obtained by digesting calomel (mercurous 
chloride) with an excess of caustic alkali; it forms black 
• The atom of mercury weighing 200 occupies 2 volumes, and hence its vapor 
density is hat/ its combining weight. 212 
Elementary Chemistry. 
powder, which undergoes decomposition on exposure to light, 
or, on heating to 100°, into metallic mercury and the red 
oxide. Mercuric oxide, Hg O, is obtained by moderately 
heating the nitrate ; it may also be prepared by heating the 
metal to about 300° in the air, or by precipitating the nitrate 
with caustic potash. The sulphides correspond to the oxides ; 
mercurous suphide, Hg2 S, is an unstable black compound, 
prepared by passing sulphuretted hydrogen through a solu- 
tion of mercurous salt. Mercuric Sulphide, cinnabar, or ver- 
milion, Hg S, is a more important substance. It occurs 
native, and may be prepared artificially by heating a mixture 
of sulphur and mercury. When precipitated from a solution 
of mercuric salt by sulphuretted hydrogen, the sulphide is 
black, but on sublimation becomes red. The chlorides of 
mercury are important compounds. Mercurous chloride, 
or calomel, Hg2Cl2, and mercuric chloride, or corrosive 
sublimate, HgCl2. 
Mercurmis Chloride, Calomel, Hg2 Cl2, is generally pre- 
pared by heating a mixture of three parts of finely-divided 
metallic mercury with four parts of corrosive sublimate ; the 
metal combines with half the chlorine of the corrosive sub- 
limate, and one atom of calomel is formed, Hg Cl2 + Hg = 
Hg2 CI2. The calomel sublimes, and is deposited in a solid 
cake; it must be well washed in order to free it from any 
soluble mercuric chloride which may remain undecomposed. 
Calomel, a white powder, is insoluble in water, but is decom- 
posed by potash or ammonia. It is used largely in medicine. 
Mercuric Chloride, or Corrosive Sublimate, Hg Cl2, is pre- 
pared on a large scale by heating an intimate mixture of 
equal parts of mercuric sulphate and common salt; it is also 
formed when mercury burns in chlorine. It acts as a violent 
poison ; it is soluble in water, crystallizing in rectangular 
octohedra, fuses at 265°, and boils at 295°. The other 
important soluble salts of mercury are the mercurous and 
mercuric nitrates, respectively obtained by acting on mercury 
with an excess of dilute nitric acid, and by dissolving mercuric 
oxide in nitric acid. The mercury compounds can be readily Elementary Chemistiy. 
213 
recognized: (i) by precipitation of black mercuric sulphide, 
insoluble in nitric acid ; (2) by the reduction of liquid globules 
of the metal when any compound is strongly heated with 
sodium carbonate in a small tube ; (3) by the deposit of 
metallic mercury on copper. The mercurous salts are dis- 
tinguished by precipitating calomel when a chloride is added 
to a soluble salt; whilst the mercuric salts may be detected 
by the formation of red mercuric iodide. 
3- Silver. Symbol Ag. Combining Weight 108. Speci- 
fic Gravity 105. 
Silver was known to the ancients. It is found in the native 
state, as well as combined with sulphur, antimony, chlorine, 
and bromine. It is also contained in small quantities in ga- 
lena (p. 202), and it can be extracted with profit from the 
lead prepared from this ore, even when the lead contains only 
two or three ounces of silver to the ton. The method thus 
adopted for the extraction of the silver depends upon the fact 
that the whole of the silver can be concentrated into a small 
portion of lead, by crystallization ; metallic lead free from 
silver separates out in crystals, and a rich alloy is left. When 
this reaches the concentration of 300 oz. silver to the ton, the 
alloy undergoes the operation of cupellation, in which the 
mixture is melted in a furnace on a porous bed of bone-earth, 
and a blast of air blown over the surface : the lead oxidizes, 
and the oxide (litharge) fuses, and partly runs away and partly 
sinks into the porous bed of the furnace, whilst the silver 
remains behind in the metallic state. 
For the extraction of silver from the other ores, a process 
termed amalgamation is employed, in which mercury is used 
to dissolved the metallic silver. The argentiferous ores of 
Germany, in which the silver occurs in combination with sul- 
phur, are worked in a different manner; the ore is roasted in 
a furnace with common salt, by which means the silver sul- 
phide is converted into chloride ; the mixture is then placed 
in casks made to revolve, and scrap-iron and water is added. 
The iron reduces the silver to the metallic state, and when 214 
Elementary Chemistry. 
this is fully accomplished, metallic mercury is added; this 
forms a liquid amalgam with the silver (and gold, if any be 
present), and by distilling the mercury off, the silver is ob- 
tained in an impure state. A somewhat different method is 
employed in South America, where fuel is expensive. Silver 
possesses a bright white color and a brilliant lustre, which it 
does not lose in pure air at any temperature, but when melted 
in the air it possesses the singular power of absorbing mecha- 
nically a large volume (twenty-two times its bulk) of oxygen ; 
this gas it again gives out on solidifying, a phenomenon tech- 
nically known as the “spitting ” of silver. 
Silver is probably the best conductor of heat and electricity 
known, and is extremely ductile ; one gramme of metal can 
be drawn out into a wire of 2,600 metres in length. Sulphur 
combines at once with silver, forming a black sulphide ; silver 
articles long exposed to the air tarnish from this cause. 
Silver is easily soluble in nitric acid, the nitrate being formed 
and nitric oxide gas being evolved. 
Alloys of Silver. Silver itself is largely used in the pure 
state for various purposes in the arts, but it is usually alloyed 
with a small quantity of copper when employed as coin or for 
articles of plate. The English coinage contains 7-5 per cent 
of copper in the standard silver, whilst the French contains 10 
per cent. 
Silver forms two compounds with oxygen, Ag40 and AgaO. 
The first of these is called silver suboxide, it is a black pow- 
der which readily undergoes decomposition ; the second, 
termed silver oxide, is obtained in the form of a brown pre- 
cipitate, when caustic potash is added to a solution of silver 
nitrate. From this oxide, which is decomposed into metal 
and oxygen on heating, the ordinary silver salts may be 
derived by dissolving in acids. Silver nitrate, Ag N03, is 
the most important soluble salt of silver. It is obtained in 
the form of large transparent tabular crystals on evaporating 
a solution of silver in nitric acid, and is soluble in its own 
weight of cold and half its weight of hot water, and in four 
parts of alcohol. Silver nitrate fuses easily on heating, and Elementary Chemistry. 
215 
when cast into sticks goes by the name of lunar caustic. This 
salt undergoes decomposition when exposed to the sunlight 
in contact with organic matter, and a black substance, prob- 
ably consisting of the suboxide, is formed ; hence it is em- 
ployed in the manufacture of an indelible ink for marking 
linen and other fabrics. 
Of the insoluble silver salts, the chloride, Ag Cl, is the 
most important. This salt occurs in nature, and is then 
known as horn silver, and is precipitated as a white curdy 
mass when a solution of a chloride and a silver salt are 
brought together. When exposed to sun- or daylight, the 
white chloride becomes tinted of a purple color, which in- 
creases in shade as the action of light continues ; this colora- 
tion arises from a partial decomposition of the salt, a small 
quantity of subchloride and free hydrochloric acid being 
formed ; in presence of organic matter this change takes 
place much more rapidly, and upon this fact the phenomena 
of photography depend. Silver chloride fuses at about 260°', 
and at higher temperatures volatilizes ; it is easily reduced to 
metallic silver in presence of zinc and sulphuric acid. The 
chloride is perfectly insoluble in pure water, but it dissolves 
appreciably in strong hydrochloric acid and in a solution of 
common salt, whilst it dissolves easily in ammonia ; it is also 
easily soluble in a solution of sodium hyposulphite, and it is 
for this reason that the latter salt is used for “ fixing ” photo- 
graphic pictures, that is, dissolving out the unaltered silver salt, 
and thus rendering the image permanent. Silver bromide, 
Ag Br, falls as a white precipitate when silver nitrate is added 
to an alkaline bromide ; it is also acted upon by the light, 
and is soluble in ammonia and an alkaline hyposulphite. The 
iodide, Agl, is a yellow powder, insoluble in water and am- 
monia, but dissolved by an alkaline hyposulphite. Silver 
sulphide, Ag2S, occurs native in cubic crystals, as silver 
glance ; it is precipitated as a black powder by passing sul- 
phuretted hydrogen through solutions of the salts of silver. 
Silver can be easily detected when in solution by the precipi- 
tation of the white curdy chloride, insoluble in water and 216 
Elementary Chemistry. 
nitric acid, and soluble in ammonia: the metal can be easily 
obtained in malleable globules before the blowpipe, whilst it 
is reduced from its solutions by iron, copper, and mercury. 
Silver is always estimated quantitatively either as the chloride 
or as the metal. 
XI. Group, i, Gold. 2, Platinum, and the rare 
Platinum-like Metals. 
I. Gold. Symbol Au (Aurum). Combining Weight 197. 
Specific Gravity ig'3. 
Gold is always found in the metallic state ; it occurs in 
veins in the older sedimentary or in the plutonic rocks, and 
in the detritus of such rocks ; it occurs in traces in the sand 
of most rivers, and although found generally in small quanti- 
ties, it is a widely diffused metal. Previous to the dis- 
coveries of the gold-fields of California and Australia, it was 
obtained from certain iron pyrites. In order to obtain the 
gold, the detritus or sand which contains the metal is washed 
in a “cradle” or other arrangement, by means of which the 
lighter particles of mud or mineral are washed away, whilst 
the heavier grains of gold sink to the bottom of the vessel. 
When gold has to be worked in the solid rock, the mineral is 
crushed to powder and then shaken up with mercury, and the 
gold thus extracted by amalgamation. 
Gold possesses a brilliant yellow color, and, in thin films, 
transmits green light; it is nearly as soft as lead; it can be 
drawn out into fine wire, and is the most malleable of all the 
metals. It does not tarnish at any temperature, in dry or 
moist air, nor is it affected by sulphur like silver; it is not 
acted upon by any single acid (except selenic), but dissolves 
in presence of free chlorine and in nitro-hydrochloric acid. 
At high temperatures gold is slightly volatile. Pure gold is best 
prepared by dissolving the ordinary metal in aqua regia, and 
adding ferrous sulphate, which is oxidized to ferric salt and 
precipitates the gold as a brown powder. The standard gold Elementary Chemistry. 
217 
of our country is an alloy of gold and copper in the propor- 
tion of 11 of gold to 1 of copper, or 8-33 per cent, of the latter 
metal; this alloy is harder and more fusible, but less ductile 
than pure gold. 
Gold unites with oxygen in two proportions, forming Gold 
suboxide, Au2 O, and Gold oxide, Aua 03. Neither of these 
oxides forms salts with acids ; but the latter unites with bases 
to form compounds called Aurates. Gold oxide is obtained 
by adding zinc-oxide or magnesia to a solution of gold chlo- 
ride : the oxide falls as a brown powder, from which the zinc 
can be separated by nitric acid. Gold oxide decomposes, in 
direct sunlight, into metal and oxygen, and is also reduced 
when heated to a temperature of about 250°. The most im- 
portant compound of gold oxide is fulminating gold; this 
substance is obtained by acting on a solution of gold with 
excess of ammonia; a yellow-brown powder is precipitated, 
which, when dry, explodes very easily when heated to ioo°, 
or when struck with a hammer. There are two gold chlorides 
known : (1) gold chloride, Au Cl, obtained as an insoluble 
white mass when gold trichloride is heated to the melting 
point of tin ; (2) the trichloride, AuCI3, obtained when gold 
is dissolved in aqua regia. This is the most important com- 
pound of gold. On evaporating the solution, crystals of a 
compound of gold trichloride and hydrochloric acid, are de- 
posited. Gold trichloride also forms crystalline compounds 
with the alkaline chlorides. Gold salts can be easily recog- 
nized by the brown precipitate of metallic gold formed on 
addition of ferrous salts, which can be reduced to a globule 
before the blowpipe ; and also by the formation of a purple 
color (purple of Cassius), when gold trichloride is added to a 
dilute solution of a mixture of the two tin chlorides. 
2. Platinum. Symbol Pt Combining Weight igyq.. Spe- 
cific Gravity 21 ’5. 
Platinum is a comparatively rare metal, which always oc- 
curs in the native state, and generally alloyed with five other 
metals, viz., palladium, rhodium, iridium, osmium, and ruthe- 218 
Elementary Chemistry. 
nium. This alloy occurs in small grains in detritus and gravel 
in Siberia and Brazil; it has not been found in situ in the 
original rock, which probably belongs to the old plutonic 
series. 
The original mode of obtaining the metal was to dissolve 
the ore in aqua regia, and precipitate the platinum (together 
with several of the accompanying metals) with sal-ammoniac, 
as the insoluble double chloride of ammonium and platinum, 
2NH4CI, PtCl4. This precipitate, on heating, yields metallic 
platinum in a finely divided or spongy state, and this sponge, 
if forcibly pressed and hammered when hot, gradually as- 
sumes a coherent metallic mass, the particles of platinum 
welding together, when hot, like iron. A new mode of pre- 
paring the metal has recently been proposed, the ore being 
melted in a very powerful furnace heated with the oxyhydrogen 
blowpipe. In this way a pure alloy of platinum, iridium, and 
rhodium is formed, the other constituents and impurities of 
the ore either being volatilized by the intense heat, or absorbed 
by the lime of which the crucible is composed. This alloy is 
in many respects more useful than pure platinum, being harder 
and less easily attacked by acids than the pure metal. 
Platinum possesses a bright white color, and does not 
tarnish under any circumstances in the air ; it is extremely 
infusible, and can only be melted by the heat of the oxy- 
bydrogen blowpipe. It is unacted upon by the ordinary acids, 
but dissolves in aqua regia, and hence platinum vessels are 
much used in the laboratory. Caustic alkalies, however, act 
upon the metal at high temperatures. When finely divided, 
metallic platinum has the power of condensing gases on to 
its surface in a remarkable degree ; the effect of bringing 
spongy platinum in contact with a mixture of oxygen and 
hydrogen has already been mentioned. Platinum and oxygen 
unite in two proportions to form—(1) Platinous Oxide, Pt O ; 
and (2) Platinic Oxide, Pt 02. The first of these oxides is a 
black powder, easily decomposed on heating, and yielding a 
series of unstable salts ; the second is obtained as a brown 
hydrate, by adding to a solution of platinic nitrate half its Elementary Chemistry. 
219 
equivalent of caustic potash ; the hydrate, when heated, first 
loses its water, forming the anhydrous oxide, and then parts 
with its oxygen, leaving the metal. Platinous chloride, PtCl2, 
is a green insoluble powder, obtained by heating the higher 
chloride to 200°; platinic chloride, PtCU, is the most impor- 
tant platinum compound. It is obtained as a yellowish-red 
solution by dissolving the metal in aqua regia; on evapora- 
tion, crystals of a compound of platinic chloride with hydro- 
chloric acid separate out. The platinic chloride combines with 
many alkaline chlorides to form double salts ; these compounds 
with potassium, rubidium, caesium, and ammonium, are insoluble 
in water, and are isomorphous, crystallizing in cubes, whilst 
the sodium salt is soluble and crystallizes in large prisms. 
Platinous chloride, when acted upon by ammonia, gives rise 
to several very remarkable compounds, containing platinum, 
nitrogen, and hydrogen ; these substances act as bases, and 
form a well-defined series of salts. These bases may be 
considered as molecules of ammonia, in which the hydrogen 
has been partly replaced by either a diatomic or tetratomic 
platinum. 
For the properties of the rare metals palladium, rhodium, 
ruthenium, iridium, and osmium, the larger manuals must 
be consulted. 
LESSON XXVI. 
Spectrum Analysis, 
An entirely new branch of chemical analysis, of great 
delicacy and importance, has recently been developed, chiefly 
by the researches of Bunsen and Kirchhoff, the principles of 
which may here be shortly stated. 
It has long been known that certain chemical substances, 
especially the salts of the alkalies and alkaline earths, when 
strongly heated in the blowpipe, or other nearly colorless 220 
Elementary Chemistry. 
flame, impart to that flame a peculiar color, by the occurrence 
of which the presence of the substance may be detected ; if 
many of these substances are present together the detection 
of each by the naked eye becomes impossible, owing to the 
colors being blended and thus interfering with each other. 
Thus, for instance, the sodium compounds color the flame 
an intense yellow, whilst the potassium salts tinge the flame 
violet; the yellow soda color is, however, so much more 
intense than the purple potash tint, that a small trace of soda 
prevents the eye from detecting the purple, even if large 
quantities of potash salts are present. This difficulty is alto- 
gether overcome, and this method of observation rendered 
extremely sensitive, if, instead of regarding the flame with the 
naked eye, it is examined through a prism. This consists of 
a triangular piece of glass, in passing through which the light 
is refracted, or bent out of its course—each differently colored 
ray being differently refracted, so that if a source of white 
light, such as the flame of a candle is thus regarded, a con- 
tinuous band of differently colored rays is observed—the 
compound white light being resolved into all its variously 
colored constituents. This colored band is termed a Spec- 
trum, and each source of pure white light gives the same 
ccmtinuoiis spectrum, stretching from red (the least refrangible) 
to violet (the most refrangible) color, identical in fact with 
the colors of the rainbow. 
If these colored flames are examined by means of a prism, 
the light being allowed to fall through a narrow slit upon the 
prism, it is at once seen that the light thus refracted differs 
essentially from white light, inasmuch as it consists of only a 
particular set of rays, each flame giving a spectrum contain- 
ing a few bright bands. Thus the spectrum of the yellow 
soda flame contains only one fine bright yellow line, whilst the 
purple potash flame exhibits a spectrum in which there are two 
bright lines, one lying at the extreme red, and the other at the 
extreme violet end. These peculiar lines are always pro- 
duced by the same Chemical element, and by no other known 
substance ; and the position of these lines always remains Elementary Chemistry. 
221 
unaltered. When the spectrum of a flame tinted by a mixture 
of sodium and potassium salts is examined, the yellow ray of 
sodium is found to be confined to its own position, whilst the 
potassium red and purple lines are as plainly seen as they 
would have been had no sodium been present. 
The colored flames which are exhibited by the salts of 
lithium, barium, strontium, and calcium, likewise each give 
rise to a peculiar spectrum, by means of which the presence 
or absence of very small quantities of these substances can be 
ascertained with certainty when mixed together, simply by 
observing the presence or absence of the peculiar bright 
bands characteristic of the particular body. 
The advantage which this new method of analysis possesses 
over the older processes lies in the extreme delicacy, as well 
as in the great facility, with which the presence of particular 
elements can be detected with certainty. Thus a portion of 
sodium salt less than the — th part of a grain can be 
100,000,000 1 0 
detected ; and compounds are found to be most widely dis- 
seminated throughout the earth, which were supposed to 
occur very seldom. The extreme delicacy of the method is 
seen when we learn that every substance which has even been 
exposed to the air for a moment gives the soda line, when 
placed in a colorless flame ; and when we find that the 
lithium compounds, which were formerly supposed to be con- 
tained in only four minerals, by aid of spectrum analysis are 
found to be substances of most common occurrence, being ob- 
served in almost all spring waters, in tea, tobacco, milk, and 
blood, but existing in such minute quantities as to have alto- 
gether eluded recognition by the older and less delicate 
analytical methods. ~—-—th part of a grain of lithium can 
J 6,000,000 1 0 
thus be detected. A still more striking proof of the value of 
spectrum analysis lies in the fact of the recent discovery of 
four new elementary bodies by its means ; two new alkaline 
metals, rubidium and caesium, having been found, together 
with potash and soda in certain mineral springs, and two new 
metals, thallium and indium, having been respectively de- 222 
Elementary Chemistry. 
tected in iron pyrites and zinc ores. The new alkaline 
metals resemble potassium so closely in their properties, 
that it would be nearly impossible to have detected them by 
the ordinary analytical methods, although their spectra exhibit 
very distinct bright bands not seen in the potassium or any 
other known spectrum. The metal thallium was discovered 
by observing a splendid green line which did not belong to 
any known substance ; whilst indium was recognized by the 
presence of a hitherto-unobserved fine dark blue line. 
It is not only those bodies which have the power of im- 
parting color to a flame which yield characteristic spectra, for 
this property belongs to every elementary substance, whether 
metal or non-metal, solid, liquid, or gas ; and it is always 
observed when such element is heated to the point at which 
its vapor becomes luminous, for then each element emits the 
peculiar light given off by it alone, and the characteristic 
bright lines become apparent when its spectrum is observed. 
Most metals require a much higher temperature than the 
common flame, in order that their vapors should become lumi- 
nous ; but they may be easily heated up to the requisite 
temperature by means of the electric spark, which, in passing 
between two points of the metal in question, volatilizes a 
small portion, and heats it so intensely as to enable it to give 
off its peculiar light. Thus all the metals, among others iron, 
platinum, silver, and gold, may each be recognized by the 
peculiar bright lines which their spectra exhibit. 
The permanent gases also yield characteristic spectra when 
they are strongly heated, as by the passage of an electric 
spark ; thus, if the spark be passed through an atmosphere 
of hydrogen gas, the light emitted is bright red, and its spec- 
trum consists of one bright red, one green, and one blue line ; 
whilst in nitrogen gas the spark has a purple color, and the 
peculiar and complicated spectrum of nitrogen is observed 
when this spark is examined with a prism. 
The instrument used in these experiments is termed a 
spectroscope. It consists of a prism (a, Fig. 57), fixed upon a 
firm iron stand, and a tube (b) carrying the slit (d) through Elementary Chemistry. 
223 
which the rays from the colored flame (e) fall upon the prism, 
and being rendered parallel by passing through a lens. The 
light, having been refracted, is received by the telescope (f), 
and the image magnified before reaching the eye. For exact 
Fig. 57. 
experiments, the number of prisms and the magnifying power 
are increased, and arrangements made for bringing two 
spectra into the field of view at once, so as to be able to 
make any wished-for comparison of the lines. 
As none of these lines overlie one another, if any number 
of different substances were present together in a flame, it 
would be easy to detect the presence of each ingredient by 
the appearance of all its characteristic lines. 
Solar and Stellar Chemistry. 
If sunlight be allowed to fall upon the slit of the spectro- 
scope, it is observed that the solar spectrum thus obtained 
differs essentially from the spectra which we have hitherto 
considered, inasmuch as it consists of a band of bright light, 
passing from red to violet, but intersected by a very large 
number of fine black lines, of different degrees of breadth 
and shade, which are always present, and always occupy 
exactly the same relative position in the solar spectrum. These 224 
Elementary Chemistry. 
lines indicate the absence in sunlight of particular rays, and 
they may be considered as shadows, or spaces where there is 
no light; they are called “ Fraunhofer1 s ” lines, after a German 
optician, who first satisfactorily mapped and described them. 
In the last few years the existence of these lines has be- 
come a matter of great importance and interest, as it is by 
their help that the determination of the chemical constitution 
of the sun and far-distant fixed stars has become possible. 
The spectra of the moon and planets (reflected sunlight) are 
found to exhibit these same lines in unaltered position, whilst 
in the spectra of the fixed stars, dark lines also occur, but 
these stellar lines are different from those seen in direct and 
reflected sunlight. Hence the conclusion has been long 
drawn that the Fraunhofer’s lines are in some way produced 
in the body of the sun itself; but it is only recently that 
the cause of their production has been discovered by Kirch- 
hoff, and thus the foundation laid for the science of solar and 
stellar chemistry. 
If the positions of these dark lines in the solar spectrum 
be carefully compared in a powerful spectroscope with those 
of the bright lines in the spectra of certain metals, such as 
sodium, iron, and magnesium, it is seen that each of the 
bright lines of the particular metal coincides not only in posi- 
tion, but also in breadth and intensity, with a dark solar line ; 
so that if the apparatus be so arranged that a solar and 
metallic spectrum be both allowed to fall, one below the 
other in the field of the telescope, the bright lines of the 
metal are all seen to be continued in dark solar lines. In the 
case of metallic iron alone, more than sixty such coincidences 
have been observed, and the higher the magnifying power 
employed, the more striking and exact does this coincidence 
appear. 
With other metals—such, for instance, as gold, antimony, 
lithium—no single coincidence can be noticed, whilst all the 
lines of certain other metals have their dark representatives 
in the sun. From these facts, it is clear that there must be 
some kind of connection between the bright lines of these Elementary Chemistry. 
225 
metals and the coincident dark solar lines, as such coin- 
cidences cannot be the result of mere chance. Is the coin- 
cidence of the dark solar lines with the bright iron lines 
caused by the presence of iron in the sun ? And if so, how 
do the lines come to appear dark in the solar spectrum ? 
The explanation of this is given by an experiment, in 
which the bright metallic lines are reversed, or changed into 
dark lines. Thus the bright yellow soda lines (coincident 
with Fraunhofer’s line D) can be made to appear as a dark 
line, by allowing the rays from a strong source of white light 
(such as the oxyhydrogen light) to pass through a flame 
colored by soda, and then to fall upon the slit of the spec- 
troscope. Instead of then seeing the usual soda spectrum of 
a bright yellow double-line upon a dark ground, a double 
dark line, identical in position and breadth with the soda line, 
will be seen to intersect the continuous spectrum of the white 
light. Here then the yellow flame has absorbed the same 
kind of light as it emits, a consequent diminution of intensity 
in that part of the spectrum occurred, and a dark line made 
its appearance. In like manner the spectra of many other 
substances have been reversed., each substance in the state of 
vapor having the power of absorbing the same rays it emits, 
or being opaque for such rays. 
The explanation of the existence of dark lines in the solar 
spectrum, coincident with bright metallic lines, now becomes 
evident : these dark lines are caused by the passage of white 
light through the glowing vapor of the metals in question, 
present in the sun’s atmosphere, and these vapors absorb 
exactly the same kind of light which they are able to emit. 
The sun’s atmosphere, therefore, contains these metals in the 
condition of glowing gases, the white light proceeding from 
the solid or liquid strongly-heated mass of the sun which 
lies in the interior. * 
By observing the coincidences of these dark lines with the 
bright lines of terrestrial metals, we arrive at a knowledge of 
the occurrence of such metals in the solar atmosphere with as 
great a degree of certainty as we are able to attain to in any 226 
Elementary Chemistry. 
question of physical science. The metals hitherto detected 
in the sun’s atmosphere are nine in number, viz., iron, sodium, 
magnesium, calcium, chromium, nickel, barium, copper, and 
zinc. Hydrogen is also known to exist in the sun. 
Stellar Chetnistry. The same methods of observation and 
reasoning apply to the determination of the chemical consti- 
tution of the atmospheres of the fixed stars, as these are self- 
luminous suns ; but the experimental difficulties are greater, 
and the results, therefore, are as yet less complete, though 
not less conclusive, than is the case with our sun. 
The spectra of the stars all contain dark lines, but these 
are for the most part different from the solar lines, and differ 
from one another; hence we conclude that the chemical con- 
stitution of the solar and stellar atmospheres is different. 
Many of the substances known on this earth have been de- 
tected in the atmosphere of the stars, by Mr. Huggins and 
Professor W. A. Miller, to whom we owe this most impor- 
tant discovery. Thus the star called Aldebaran contains 
hydrogen, sodium, magnesium, calcium, iron, tellurium, anti- 
mony, bismuth, and mercury; whilst in Sirius only sodium, mag- 
nesium, and hydrogen have with certainty been detected. 
In examining the spectra of some of the nebulae, a striking 
difference is observed : the stellar spectra, it will be re- 
membered, resemble the spectrum of the sun, inasmuch as 
each consists of a bright ground intersected with dark lines ; 
the spectra of the nebulas, on the other hand, consist simply 
of bright lines, like the spectra of hydrogen, nitrogen, or 
any of the metals. Hence we conclude that the nebulas are 
masses of glowing gas, and do not consist, like the sun and 
stars, of a solid or liquid mass, surrounded by a gaseous at- 
mosphere. 
The whole subject of solar and stellar chemistry is still in 
its earliest infancy, but the results already obtained lead to 
the belief that our knowledge of the chemical composition 
of those far-distant bodies will become more intimate as 
the methods of experiment and observation are gradually 
perfected. Elementary Chemistry. 
227 
LESSON XXVII. 
Chemistry of the Carbon Compounds, or 
Organic Chemistry. 
Organic Chemistry is defined as the chemistry of the 
carbon compounds. Many of these compounds exist already 
formed in the bodies of plants and animals, and hence the 
name of Organic Chemistry was given to this branch of the 
science. It is separated from the foregoing, Inorganic por- 
tion, not because any real difference exists in the laws re- 
gulating the formation of the bodies classed under these two 
great divisions, but because the number of compounds which 
have to be studied under organic chemistry is so large, and 
their constitution frequently so complicated, that they are at 
present best considered after the more simple inorganic com- 
pounds have been described. 
Certain organic substances do, indeed, differ fundamentally 
in constitution and mode of formation from any inorganic 
compound, inasmuch as these exhibit what is termed an or- 
ganized structure, being the sole and direct product of animal 
or vegetable life. Such an organized structure is seen in the 
simple cell, the germ of living organisms. It cannot be arti- 
ficially prepared from its elementary constituents, whereas 
any crystalline or liquid organic body may possibly be thus 
built up from its elements. 
The first striking peculiarity which the carbon compounds 
exhibit, is their extraordinary number, those already known 
far exceeding all the compounds of the other elements taken 
together, and new ones being daily brought to light. A 
second peculiarity of these compounds is, that they are al- 
most all of them formed by the union of carbon in different 
proportions with one or more of three other elements; viz., 
hydrogen, oxygen, and nitrogen. 
The cause of the multiplicity of the carbon compounds is 
to be sought in a fundamental and distinctive property of 
carbon itself. This consists in the power which this element 228 
Elementary Chemistry. 
possesses, in a much higher degree than any of the others, of 
uniting with itself to form complicated compounds, contain- 
ing an aggregation of carbon atoms united with either hydro- 
gen, oxygen, nitrogen, or several of these, bound together to 
form a distinct chemical whole. These molecules, or groups 
of atoms, play in organic chemistry a part similar to that of 
the metals or the simple molecules, such as the radicals N02 
and S02, met with in the inorganic department of the science ; 
they form whole series of compounds, in each of which the 
group of atoms can always be identified, and in all the family 
likeness recognized. Hence organic chemistry was formerly 
called the chemistry of the compound radicals, a name given 
to these groups of atoms, which act as if they were elements. 
We have already seen (p. 138), that the atoms of different 
elements possess different powers of combination or atomi- 
cities ; that is, one atom of an element is capable of replacing 
either one or more atoms of hydrogen in combinations : thus 
Chlorine, Potassium, and Silver are monads, or can replace 
only one atom of hydrogen ; whilst Oxygen, Sulphur, and 
Magnesium are dyad elements, capable of replacing two of 
hydrogen ; and Nitrogen, Phosphorus, and Aluminium are 
triads, or play the part of three atoms of hydrogen. Carbon, 
on the other hand, is a tetrad, or tetratomic element ; and just 
as the compounds HC1, H20, HSN are the representatives of 
the compounds of the monad, dyad, and triad elements, so 
marsh gas, H4C, is the characteristic and representative com- 
pound of tetratomic carbon. 
In this compound the four combining units of the carbon 
atom are saturated, or satisfied, by union with the four atoms 
of hydrogen, and hence this is said to be a saturated com- 
pound. Four atoms of any other monad would, however, 
satisfy this condition ; and we find, in fact, that one or more 
of the four atoms of hydrogen can be substituted, step by 
step, for chlorine, so that the following substitution products 
are obtained : 
CHL CH.Cl. CH2 Cl,. CH Cl,. C CL Elementary Chemistry. 
229 
The four combining powers of the carbon atom can be 
saturated not only by the union of the carbon to four monad 
atoms, but also by its union to two dyad atoms, or to one 
triad and one monad, or to one tetrad atom. Thus in carbon 
dioxide (carbonic acid), 02 C, and carbon disulphide, Sa C, 
we have a carbon atom saturated with two dyads ; in hydric 
cyanide (prussic acid), HNC, we have a carbon atom satu- 
rated with a triad (N) and a monad (H) element. 
When two atoms of tetratomic carbon unite together, a 
new radical or group of atoms is formed ; this duplication of 
the carbon element takes place by a combination of one of the 
four combining units of one atom with one of the four units 
of the other atom ; so that two of the eight original combi- 
ning units are saturated or disposed of, and only six remain 
free to combine. Hence, whilst CH4 is the type of the mono- 
carbon series, C2 H0 is that of the dicarbon series, and simi- 
larly, C3 Hs that of the tricarbon series ; and no compound 
of any of these three series is known containing respectively 
more than four, six, or eight atoms of a monad. 
Other groups of bodies exist in which all the combining 
powers of the carbon are not fully satisfied ; such bodies, for 
instance, as carbonic oxide, CO, and olefiant gas, Ca H4. 
These substances are termed non-saturated compounds, and 
possess the peculiar property of uniting directly with other 
elements in such quantity as to fill up the vacant combining 
powers. Thus carbonic oxide and olefiant gas both combine 
directly with Cla to form saturated compounds, which con- 
form to the law above stated ; whilst, on the other hand, we 
find it impossible to obtain a combination of chlorine with 
C02, or with C2 H6. 
The following graphical representation of these three typi- 
cal compounds (see p. 230) may help to render their mode of 
formation more evident. 
From these figures it is seen that an addition of C Ha is 
necessary to pass up the series. This addition can actually 
be experimentally made, and the higher and more complicated 
carbon groups thus obtained from the lowest and simplest Elementary Chemistry. 
230 
one, whilst this, in its turn, can be prepared from its con- 
stituent elements. We are well acquainted with no less than 
fifteen of this series, containing from one to fifteen atoms of 
carbon, combined with a saturating quantity of hydrogen, and 
each member of the series forms a starting-point for a num- 
ber of peculiar derivatives, all containing a common constitu- 
ent, and exhibiting a family likeness. 
The compounds obtained from each of these series of 
Monocarbon Series. 
Dicarbon Series. 
Tricarbon Series. 
mono- di- tri- and higher carbon groups, may indeed be com- 
pared with those of the inorganic metals, and each different 
carbon series may be supposed to contain a group of atoms of 
carbon and hydrogen, which plays the same part in these 
compounds as the metal does in the metallic salts, and to 
which the name of compound radical has been given. The 
radical contained in each of the three typical substances just 
mentioned is found to be a hydrocarbon, containing one 
atom less hydrogen than the original type, and each of these 
bodies is therefore termed the hydride of a radical, and con- 
H ) 
sidered to be a molecule of hydrogen v, in which one atom 
of the hydrogen is replaced by a radical ; thus we have : 
Monocarbon Series. 
Dicarbon Series. 
Tricarbon Series. 
Methyl- CH3 
Hydride H 
Ethyl- C2H5 
Hydride H 
Propyl- C3H, 
Hydride H Elementary Chemistry. 
231 
By replacing the one of hydrogen out of the radical by chlorine, 
we obtain the corresponding chlorides : viz.— 
Monocarbon Series. 
Dicarbon Series. 
Tricarbon Series. 
Methyl- CH3 
Chloride Cl 
Ethyl- C2H5 
Chloride Cl 
Propyl- CsH7 
Chloride Cl 
And by replacing the same hydrogen by the monatomic radical 
H O in each hydride, we obtain an important class of bodies 
termed the alcohols. 
Monocarbon Series. 
Dicarbon Series. 
Tricarbon Series. 
Methyl- CH3 ( n 
Alcohol H \ u 
Ethyl- C2H5) 0 
Alcohol H )u 
Propyl- C3H7 > n 
Alcohol H |u 
The molecules of the radicals methyl CH3, ethyl C2 HB, and 
propyl Cs Ht> in these several compounds remain indivisible 
throughout all the derivatives, and give the peculiar characters 
to each series. 
As in mineral chemistry we have radicals (see p. 139), some 
of which are monads, and some dyads, triads, or tetrads, so 
amongst the carbon compounds some radicals exist in which 
more than one combining power remains unsaturated, and 
which therefore act as polyatomic radicals; thus methylene 
II II II 
CH2, ethylene C2H4, and propylene, Ca H6, are dyads ; whilst 
in 
glyceryl, C3 H5, is a triad. 
These bodies give rise to a large class of derivatives, each 
containing the radical or group of carbon and hydrogen atoms. 
All the substances analogous to the foregoing, or derived from 
them, are classed as the alcohol group of organic bodies. 
Other carbon compounds are, however, known, which are 
saturated, but contain the carbon atoms more intimately 
united together, than the members of the alcohol group; the 232 
Elementary Chemistry. 
principal group of these substances is termed the aromatic 
group of organic bodies. Thus, the formula of Benzol is C6 
Ho, and in this body eighteen of the twenty-four combining 
powers of the six atoms of tetratomic carbon are saturated by 
combination of carbon with carbon. 
We shall first study the properties and mode of formation 
of some of the most important members of the alcohol group, 
and then notice the chief properties of the aromatic series of 
organic bodies. 
It follows from the tetratomic character of carbon, that 
however the carbon atoms may be united together, the com- 
bining powers which remain unsaturated must be an even 
number; hence the sum of the atoms of monad or triad 
elements united with the carbon must be an even number, 
whilst the number of dyad elements is not thus restricted. 
We have already (see note on page no) defined a molecule 
to be the group of atoms forming the smallest portion of a 
chemical substance, either simple or compound, which can 
exist in the free state. We have also seen that the molecule 
of the compound gases always occupies the same space:* 
thus the molecules of hydrochloric acid HC1, of water H20, 
of ammonia NH3, and of marsh gas CH4, occupy the same 
space, viz., 2 volumes (when H = 1 occupies 1 volume). In 
like manner the molecules of the elementary gases in the free 
state occupy the same space, or 2 volumes : thus the molecule 
of free hydrogen |, that of oxygen q |, that of nitrogen 
|, and that of sulphur | ; whilst that of phosphorus is 
P4 (weighing 124), of arsenic As4 (weighing 300); and that of 
Atomic and Molecular Formula. 
* Some apparent exceptions to this law must be noticed ; the molecules of certain 
bodies such as PCI5, SbCh, NH4 Cl, Hga Cb, &c., are found to occupy 4 volumes. 
It has, however, been satisfactorily proved that these substances, when heated, de- 
compose into two other bodies; thus PCls forms PCls and Cla, NH4 Cl forms NHs 
and HC1, and these occupy 4 volumes in accordance with the law. Elementary Chemistry. 
233 
mercury and cadmium Hg and Cd, respectively weighing 200 
and 112. 
We may express chemical decompositions either by atomic 
or by molecular formulae ; thus 
H + Cl = HC1 
is the atomic expression, whilst 
Ha + Cla = 2HCI 
is the molecular expression for the same reaction. In the 
first we assume a direct combination of the elements ; in the 
second we consider the reaction as a replacement of chlorine 
for hydrogen, or vice versa j and in this way we are able to 
represent every case of chemical action as a double decom- 
position. 
Classification of Organic Compounds according to Types. 
We have already seen that a large number of inorganic sub- 
stances may with advantage be classed together as being of 
one pattern, or being capable of being arranged under some 
H ) 
one typical form. Thus water, [ O, forms the type of the 
monatomic oxides and hydrates, as | O, and | O, | O, 
and | O ; as well as of the monatomic acids and salts, 
as j- O, and 1 O, &c.; whilst, by replacement of 
both atoms of hydrogen by a dyad element, we obtain the 
II II II 
diatomic oxides, such as CaO, PbO, CuO. Two atoms of 
water must be taken as the type of the di-basic acids, such 
as sulphuric and carbonic acids, possessing two atoms of 
» |o. »!o, 
replaceable hydrogen ; thus gQ s qq -j the two 
H j °» H ; °» 
atoms of water being linked together by the replacement of 
II 
one atom of hydrogen in each by the dyad radicals, S02, and 
n 
CO, In like manner the hydrates of the dyad metals are Elementary Chemistry. 
234 
constructed on the type of 2 atoms of water, thus | 02. 
The triad elements or radicals form compounds upon the 
type of 3 atoms of water ; thus Boron teroxide is g *” | 03, 
in 
PO ) 
and tribasic phosphoric acid V Os. In the same way, a 
very large number of organic bodies may be arranged under 
the types of 1, 2, 3, or more atoms of water, and thus a stri- 
king analogy between the mineral and carbon compounds is 
exhibited. Thus, for instance, the large and important fami- 
ly of the monatomic alcohols having the general formula, 
Cn H2n + 20, may all be considered as one molecule of water, 
U j 
v O, in which an atom of hydrogen is replaced by a monad 
radical having the general formula, C„ H2n + i ; a series of 
diatomic alcohols is also known of the general formula, Cn 
H2n+202, and these bodies are constituted on the type of 2 
H ) 
molecules of water, [ 02, in which 2 atoms of hydro- 
gen are replaced by a dyad radical of the formula C„ ; 
whilst, lastly, a series of triatomic alcohols are known of the 
general formula, Cn in which 3 molecules of water, 
H ) 
j_j3 [ Os, must be taken as the type, 3 atoms of hydrogen 
being replaced by a triatomic radical. 
The type of the molecule of free hydrogen pj [is also one 
upon which, as we have seen, many inorganic compounds are 
H ) 
formed; [is the molecule of hydrogen in which one 
atom is replaced by chlorine. So |, and all the mona- 
tomic chlorides, iodides, and bromides, may also be reduced 
to the same type ; whereas the diatomic chlorides, bromides, 
and iodides, such as Mg Cl2, Pb Cl2, are considered as 2 
H ) 
molecules of hydrogen, [, in which 2 of the atoms are Elementary Chemistry. 
235 
replaced by I atom of a dyad metal, and the other two by 2 
atoms of a monad ; and the aluminium and ferric chlorides 
are regarded as 6 molecules of hydrogen in which 6 atoms 
are replaced by 2 of the triad iron or aluminium, and 6 by 6 
of the monad chlorine. This type is one which we shall fre- 
quently use in organic chemistry, under which a large class 
of carbon compounds can be classed ; examples are found in 
the chlorides and hydrides of the mono- di- and tri- carbon 
series already mentioned. 
A third type upon whose model many organic compounds 
H 1 m 
are built up is that of ammonia,H > N. In mineral chemistry 
H ) 
we know of at least three other bodies belonging to this type, 
H ) m 
viz., phosphuretted hydrogen, H > P, arseniuretted hydrogen, 
Hi 
Him HI III 
H > As, and antimoniuretted hydrogen, H > Sb. In the car- 
H) Hi 
bon compounds we shall become acquainted with a numerous 
family of compound ammonias, all of which are constructed 
on the model of the simple inorganic ammonia by replacement 
of one or more atoms of hydrogen by organic radicals. 
Those organic compounds whose constitution is understood, 
may all be referred to one of these three great typical forms, 
viz.:— 
g}. S}0,andSjN, 
and by this means the consideration and survey of the 
innumerable carbon compounds is greatly simplified. 236 
Elementary Chemistry. 
LESSON XXVIII. 
Determination of the Composition of Carbon 
Compounds. 
x. Organic Analysis. Esti?nation of Carbon and Hy- 
drogen. 
As all organic compounds contain carbon, and most of 
them hydrogen, the estimation of these two constituents 
becomes a matter of importance, and the method of analysis 
remains nearly the same for all organic substances. It is 
founded upon the fact, that when any compound of carbon is 
heated to redness with excess of oxygen, it undergoes com- 
plete combustion, the carbon being oxidized to carbonic 
dioxide (carbonic acid), and the hydrogen to water, so that by 
weighing the quantity of these two products obtained by 
burning a given weight of the substance, we can ascertain the 
weight of carbon and of hydrogen which the substance con- 
tained. 
The combustion of the organic compound can either be 
made in a current of pure oxygen gas, or by mixing the body 
with pure copper oxide (Cu O), which readily parts with its 
oxygen to hydrogen or carbon at a red heat—in either method 
the products of combustion being carefully collected and 
weighed. A weighed quantity (generally about 0-3 grm.) of 
the solid substance about to be analyzed by means of copper 
oxide is brought into a combustion tube made of hard Bo- 
hemian glass (aa, Fig. 58), about 50 to 60 centimetres in 
ric. 58. Elementary Chemistry. 
237 
length, and drawn out at one end to a fine point, and open at 
the other. Before the introduction of the substance, a quan- 
tity of pure and perfectly dry, freshly-ignited, granulated, 
copper oxide is brought into the tube sufficient to fill about 
one quarter of its length, and the substance is well mixed 
with this oxide by means of a brass wire (b, Fig. 58) ; fresh 
oxide is then added, the brass wire being well cleaned from 
every possible trace of the adhering substance, until the tube 
is nearly filled. 
The apparatus intended to collect the water produced is 
now attached to the open end of the tube by means of a well- 
fitting dry cork : it consists of a tube (c), filled with porous 
pieces of calcium chloride, and accurately weighed ; this 
substance effectually absorbs all the water and aqueous vapor 
formed in the combustion ; the carbonic acid passes through 
the tube unabsorbed, and bubbles into a solution of strong 
caustic potash contained in the bulb apparatus (d), attached 
to the drying tube by a well-fitting caoutchouc joining (e). 
The increase in weight of the drying tube and potash bulbs 
gives respectively the weight of water and carbonic acid pro- 
duced. 
The combustion tube is placed in a long furnace, so that it 
can be gradually heated to redness ; this is most readily 
effected by a number of gas-burners arranged in line, so that 
each part of the tube can be gradually and separately heated 
(f). A larger number of small burners are placed under the 
part of the tube containing the substance, in order that the 
combustion may be more accurately regulated. After the 
whole arrangement has been shown to be properly air-tight, 
the part of the tube near the cork, containing only pure cop- 
per oxide, is heated; and when a length of 15-20 centi- 
metres of it is red-hot, the part of the tube containing the 
substance is gently heated, until bubbles of carbonic acid are 
seen slowly to enter the potash bulbs ; and the heat is ap- 
plied, so that this slow disengagement of carbonic acid con- 
tinues until the whole of the substance is burnt. 
When the gas ceases to come off, the whole length of the 238 
Elementary Chemistry. 
tube is strongly heated for some minutes, and as soon as the 
potash solution begins to pass back into the bulb nearest the 
combustion tube (owing to absorption of the carbonic acid), 
the drawn-out end of the tube is broken, the gas flames ex- 
tinguished at that end of the furnace, and air drawn for some 
minutes through the whole apparatus by sucking with the 
mouth through a tube placed on the end of the potash-bulbs. 
This operation is necessary, in order to collect in the potash 
the carbonic acid which still remains in the combustion-tube. 
As soon as this is finished, the analysis is'complete with the 
exception of weighing the drying tube and potash-bulbs. 
Many precautions must be taken, and much attention to de- 
tails must be paid, in order to insure accurate results in or- 
ganic analysis ; for an enumeration of these the larger 
manuals must be consulted. 
If the substance under examination is a liquid, it is sealed 
up in a small weighed glass bulb drawn out to a fine point; 
this is again weighed, the point broken off, and the bulb 
dropped into the combustion tube, and the operation con- 
ducted as above described. When nitrogen is contained in 
the body about to be analyzed, it is necessary to place some 
turnings of metallic copper in the front part of the tube to 
decompose any nitrous fumes which are formed and would be 
absorbed by the potash, and thus impair the result. 
Determination of Nitrogen. Nitrogenous organic bodies, 
when heated with caustic soda, or potash, yield the whole of 
the nitrogen which they contain in the form of ammonia. This 
evolution of ammonia is easily rendered evident by heating a 
small piece of cheese with solid caustic soda. Upon this re- 
action a method is based for determining the quantity of 
nitrogen in organic bodies ; it consists simply in heating a 
given weight of substance with a mixture of caustic soda and 
quicklime in a tube, and collecting the ammonia formed, in 
hydrochloric acid, and estimating the weight of ammonium- 
chloride produced by weighing as double platinum salt. For 
every 100 parts by weight of this salt obtained, the substance 
contains 6 35 parts of nitrogen. Elementary Chemistry. 
239 
In certain cases, viz., when the nitrogen is contained as an 
oxide in the organic substance, the foregoing method cannot 
be employed, inasmuch as these oxides are not completely 
converted into ammonia ; it is then necessary to obtain the 
nitrogen gas in the free state by heating the substance with a 
mixture of copper and mercury oxides, and passing the gases 
produced over metallic copper. All the nitrogen comes off in 
the gaseous form, and may be easily purified by caustic soda 
from the carbonic acid also evolved, and thus the volume of 
nitrogen obtained can be accurately measured. From this 
volume, measured under given circumstances of temperature 
and pressure, the weight of the nitrogen can, of course, be 
calculated. 
Chlorine, sulplmr, and phosphorus exist not unfrequently 
in organic bodies, and have to be determined: the first is 
estimated by heating the substance to redness in a tube con- 
taining pure quicklime; the chlorine forms calcium chloride, 
in which, on solution in nitric acid, the chlorine is weighed as 
silver salt. Sulphur and phosphorus are determined by heat- 
ing the organic body with a mixture of pure nitre and sodium 
carbonate, placed in a tube ; sulphuric and phosphoric acids 
are formed and estimated in the usual manner. 
Oxygen is usually obtained by difference, that is, by sub- 
tracting the sum of the weights of all the constituents which 
have been directly determined from the weight of the sub- 
stance taken: several direct methods for the estimation of 
oxygen have been proposed, but these are not often used. 
2. Determination of the Composition, Molecular Weight, 
and Formula of an Organic Compound. 
The above methods of analysis give us the percentage 
composition of the substance, and the relation between the 
number of atoms of carbon, hydrogen, oxygen, &c., con- 
tained in the compound, but we need to make a further 
determination in order to get to know the formula and 
the molecular weight of the body. Thus, in an analysis 
of glacial acetic acid, 0-395 grammes of substance was 
found to yield 0-580 grammes of carbonic acid, and 0-235 240 
Elementary Chemistiy. 
grammes of water; hence too parts of glacial acetic acid 
consist of 
Carbon .... 40-0 
Hydrogen . . . 66 
Oxygen . . . . (By difference.) 
loco 
If we divide these numbers respectively by the combi- 
40 6-6 
ning weights of carbon, hydrogen, and oxygen, — = 3-3,— 
53-4 
= 6-6, and -yg- = 3-3, we obtain the relation between the 
combining weights of these constituents present. Thus we see 
that the number of atoms of carbon and oxygen is equal, 
whilst that of hydrogen is twice as large ; the composition of 
acetic acid is, therefore, represented by C„ H2„ 0„, but we do 
not know whether the true formula is C H2 O, C2 H4 02, or 
C2 H6 03 ; or whether it contains a still higher number of 
carbon atoms. In order to decide this point, and, therefore, 
to determine the molecular weight of the substance, we must 
endeavor to find a compound of it with some well-known 
element (such as silver), in which one atom of hydrogen in 
acetic acid is replaced by one atom of silver ; that is, we 
must find the weight of C, H, and O, in the ascertained re- 
lative proportion, which forms a compound with one atom of 
silver. On examination we find that only one such compound 
of silver and acetic acid exists ; and we find by experi- 
ment that 100 parts of silver acetate contain 64-68 parts 
by weight of silver ; hence, the weight of the carbon, 
hydrogen, and oxygen, united with silver (Ag=io8), is 
35-32 x 108 
5^58— — SS'pS. In this silver acetate, however, one 
atom of hydrogen of the glacial acid was replaced by one of 
silver, so that the molecular weight of the glacial acetic acid 
is found to be 58-98 + 1 = 59-98, or its formula is : Elementary Chemistry. 
241 
2 C = 24 
4 H = 4 
2 O = 32 
6o 
The slight difference observed between the found 
and the calculated (60) molecular weight arises from un- 
avoidable errors of experiment ; the more analyses of the 
substance are made, the nearer will the mean result approach 
the calculated numbers. 
In a similar manner the molecular weights of organic 
bases are determined by ascertaining the weight of the sub- 
stance which unites with a known weight of hydrochloric 
acid to form a salt. In the case of certain organic acids and 
bases, two or more compounds containing different propor- 
tions of silver (or other metal) and hydrochloric (or other 
acid) are known, and it becomes a matter for consideration 
which of these is to be taken as containing one molecule of 
the organic compound to one atom of metal or acid; the 
choice in these cases is determined by the general proper- 
ties of all the compounds, which never fail to point out the 
true character of the substance. The same method of deci- 
sion also applies to many other bodies, such as sugar, tur- 
pentine, &c., which do not readily enter into combination with 
a metal or an acid. 
There is one most important property by which the mole- 
cular weight of volatile organic bodies can be ascertained, 
viz., the density ox specific gravity of their vapors. We have 
already seen that the vapor volume occupied by the mole- 
cule of almost all volatile compounds is twice that occupied 
by the atom of hydrogen. There are a very few exceptions 
to this general law, and these exceptions can frequently be 
explained by the fact that the substances decompose when 
heated, and that the vapor is not simply that of the original 
compound. The molecule of water, H20, weighing 18, oc- 
cupies twice as large a volume as the atom of hydrogen 242 
Elementary Chemistry. 
weighing i, or the density of water-gas is 9; so hydrochloric 
acid, HC1, weighing 36-5, occupies two volumes, and its den- 
sity is 1875, and ammonia, NH3, weighing 17, has a density 
of 8-5. 
This same simple relation also holds good in organic che- 
mistry. The molecule of every volatile organic compound 
occupies a volume twice as large as that occupied by an atom 
of hydrogen weighing 1; or the density of an organic com- 
pound is half its molecular weight. 
The experimental determination of the vapor densities of 
organic compounds thus becomes an important matter as 
serving to control the correctness of the molecular weight 
ascertained by the foregoing methods. Thus, for instance, 
the density of the vapor of acetic acid is found by experiment 
to be 30-07 (H = 1); and this accordingly gives a molecular 
weight to acetic acid of 60-14, a number agreeing with that 
obtained from purely chemical considerations (see ante, p. 241). 
Another example may serve to render evident the impor- 
tance of this relation : the combustion of acetal shows that 
the simplest relation of its constituent atoms is represented 
by the formula C3 H7 O ; * the determination of vapor density, 
however, gives the number 59-8 as the density of acetal gas, 
hence the molecular weight of acetal must be 59 x 2, and 
its formula not C3 H7 O = 59, but C6 H14 02 = 118. It is, 
of course, possible, when the molecular weight of a compound 
has been otherwise ascertained, to calculate its vapor densi- 
ty ; this calculated density will always differ slightly from 
that determined by experiment, owing to the unavoidable 
errors which occur ; this, however, does not detract from the 
value of this method of controlling the molecular formula of 
a substance. 
Determination of Vapor Density. 
Two methods are employed for determining the vapor 
* We see that as this formula contains an uneven number of hydrogen atoms 
the existence of this substance is impossible : we know that the true formula must 
be a multiple of this, which multiple we decide by the vapor density. Eleme7itary Chemistry. 
243 
density of a compound. (1) By ascertaining the weight of a 
given volume of vapor. (2) By ascertaining the volume of a 
given weight of vapor. In the first of these processes, a thin 
glass globe is employed of about 200 to 300 cubic centi- 
metres in capacity, having a finely drawn-out neck ; the 
exact weight of the globe filled at a certain temperature and 
under an observed pressure having been found, a small por- 
tion of the substance whose density is to be determined is 
brought inside, and the globe then heated by plunging it into 
a water- or oil-bath (Fig. 59) raised to a temperature much 
above the boiling point of the substance. As soon as the 
vapor has ceased to issue from the end of the neck, this end 
is hermetically sealed before a blowpipe, and the exact tem- 
perature as well as barometric pressure observed. The bulb 
thus filled with vapor is allowed to cool, and is next accurate- 
ly weighed, and the point of the neck broken under mercury ; 
the mercury rushes into the globe, owing to the vapor being 
condensed, and, if the experiment has been well conducted, 
completely fills it. From the volume of mercury which thus 
enters, the capacity of the globe is obtained. 
We have now all the data necessary for the determination. 
In the first place we have to find the weight of a given volume 
of the vapor under certain circumstances of temperature and 
Fig. 59. 244 
Elementary Chemistry. 
pressure, and we then have to compare this with the weight 
of an equal volume of hydrogen gas measured under the 
same circumstances. The following example of the vapor 
density of volatile hydro-carbon may serve to illustrate the 
method; weight of globe filled with dry air at 15-5° 23-449 
grammes; weight of globe filled with vapor at no0 23-720 
grammes ; capacity of the globe 178 cbc. As the barometric 
column stood near to 760 mm. and underwent no change from 
the beginning to the end of the experiment, no correction for 
pressure is necessary. In order to get the weight of the vacuous 
globe, the weight of air contained must be deducted from the 
weight of globe in air. Now 1 cbc. of air at 0°, and 760 mm. 
weighs 0-001293 gramme, and 178 cbc. of air at 15-5 would 
occupy o an(j the weight of this air 
is o-218 gramme : hence the weight of the vacuous bulb is 
23-231, and the weight of vapor 23-720—23-231 = 0-489 
gramme. We must now find what 178 cbc. of hydrogen at 
no° will weigh : 1,000 cbc. of hydrogen at o° weigh 0-08936 
gramme ; 178 cbc. will contract to 126-9 cbc. at o°. 126 cbc. 
of hydrogen at 0° weigh 0-01134 gramme, and this is there- 
fore the weight of 178 cbc. of hydrogen at 110°. Hence 
-° . = 43-13 is the density of the vapor, as found by 
o-o 1134 
experiment. The formula of the substance is C6 Hu, or its 
molecular weight is 86. In this example many minor correc- 
tions, such as the expansion of the glass globe, the error of 
the mercurial thermometer, &c., are not considered ; the 
above method gives results which are sufficiently accurate 
when the object is to control the molecular weight of a 
compound. 
The second method of vapor density determination con- 
sists in ascertaining the volume occupied by a given weight 
of substance when heated up to a temperature considerably 
above its boiling point. The mode of calculation is in princi- 
ple the same as that of the former method. For the details 
of manipulation the reader must refer to the larger manuals. Elementary Chemistry. 
245 
Boiling Point. 
Another important physical property of organic compounds 
is the boiling point. Every volatile chemical compound has, 
under given circumstances of pressure, a fixed and constant 
boiling point; and this property is useful in ascertaining the 
purity of an organic liquid, as well as enabling us to separate 
the constituents of a mixture by means of fractional or con- 
tinued distillation. The boiling points of the homologous 
series of hydrides, alcohols, chlorides, &c. (p. 231), rises with 
the increase of carbon, and frequently proportionally to this 
increase, although no general law connecting boiling point 
and chemical composition can be expressed. The arrange- 
ment used in the separation of liquids boiling at different 
points by means of fractional distillation is represented in 
Fig. 60. The large surface presented by the bulb tube (a) 
allows the vapor of the less volatile constituents to condense 
Fig. 60. 
and flow back into the flask containing the mixture ; the 
temperature of the vapor is indicated by the thermometer (b), 
and when the temperature rises beyond a given point the 
liquid already distilled over is removed and an empty flask 
substituted to collect the portion of liquid next coming over. 246 
Elementary Chemistry. 
LESSON XXIX. 
Monatomic Alcohol Group. 
General Characteristics. The monatomic alcohols and their 
derivatives form a very large and important group of organic 
compounds. As an example of these alcohols we may take 
ethyl alcohol, C2 H6 O, known as spirits of wine ; this sub- 
stance, in common with all the other alcohols of this series, 
may be considered as water in which One atom of 
is replaced by a radical having in this case the formula C2 H6; 
C h ) 
hence ethyl alcohol is 2 > O. Ethyl alcohol is in consti- 
K 7 
tution analogous to caustic potash, O ; and as, by adding 
hydrochloric acid to the latter, we get KC1 (potassium chloride) 
H 7 
and 1- O, so by bringing alcohol in contact with this acid 
H 7 
we get C2H5 Cl (ethyl chloride), and O ; in like manner 
the chlorides, iodides, and bromides of all the alcohol radicals 
can be obtained. The analogy of the ethyl with the potas- 
sium compounds is still further seen in the fact that an ethyl 
compound exists which stands to alcohol in the same relation 
as potassium monoxide to caustic potash ; this compound is 
C H 7 
common- or ethyl-ether, qj_j6 r O. We also have analo- 
gous compounds to the potassium salts ; thus we have, potas- 
sium nitrate, | O, ethyl nitrate, 1 O, 
?‘l 
Hydric-potassium-sulphate S02 ( 02; 
H ) 
C2H6 ) 
Hydric-ethyl sulphate , S02 f 02; 
H ) 
Potassium acetate . . | o ; Elementary Chemistry. 
247 
Ethyl acetate . . • c* R3 | 
If ethyl alcohol be exposed to oxidizing agents, it first loses 
2 atoms of hydrogen, and is converted into a new substance, 
C2 O, called ethyl aldehyde ; and if the oxidizing action 
continues longer, another product termed acetic acid is formed, 
which has the composition Both these substances 
may be regarded as containing an oxidized radical, or ethyl in 
which 2 atoms of hydrogen are replaced by I atom of oxygen ; 
aldehyde thus becomes the hydride of this radical (called 
C H O 7 
Acetyl), 2 3j_j >•, whilst acetic acid is water in which i 
r u O ) 
atom of hydrogen is replaced by acetyl: thus, 2 ’r [O. 
Aldehyde can be reduced again to alcohol directly by addition 
of 2 atoms of hydrogen, but acetic acid cannot be directly 
reduced to alcohol. 
Every alcohol can thus be oxidized, and yields an aldehyde 
and an acid which stand in the same relation to one another 
as the above-mentioned bodies. All these acids are mono- 
basic ; that is, they contain only I atom of hydrogen replace- 
able by a metal. This hydrogen can also be replaced, not 
only by the ethyl and the other alcohol radicals, giving rise to 
r IT A ) 
bodies called the compound ethers, of which, £2pj3 r O, 
acetic ether or ethyl-acetate, may be taken as an example, but 
also by acetyl itself or the other oxidized radicals; thus we 
C- H O ) 
obtain q jj3q [ O, a substance which we shall term acetyl 
acetate, but which is frequently called acetic anhydride, or 
even anhydrous acetic acid. 
Each alcohol also forms a series of compound ammonias ; 
H) 
that is, ammonia, H )- N, in which one or more atoms of hydro- 
H) 
gen are replaced by a radical: thus, for the ethyl series we 248 
Elementary Chemistry. 
C2H6I c2h6) 
have ethylamine H > N ; diethylamine, C2H5 >■ N ; and 
H ) H > 
C2 H6) 
triethylamine, C2 H6 >• N. We can, indeed, go one step 
C2 H.) 
further in the addition of ethyl, and obtain a caustic substance 
resembling potash in its properties, and analogous to the 
ammonium hydrate, 1 but containing 4 of ethyl in 
place of the 4 of hydrogen ; thus, N(C2H5)41 q ; to this sub- 
stance the name of tetra-ethyl-ammonium hydrate is given. 
Compound ammonias are also known in which one or more 
atoms of the hydrogen of ammonia is replaced by the oxygen- 
ized radical of the acids, and these compounds are termed 
Amides ; thus we have with acetyl, 
C2H30) C2H30) 
acetamide, H >- N; diacetamide, C2H30 > N; 
H ) H ) 
C2HsO) 
and ethyl-diacetamide,C2H30 > N. 
C2H6 ) 
Compounds of the alcohol radicals analogous to arsenic and 
phosphorus trihydrides are also known; thus, for instance, 
CH.l C2H6j 
C Hs >■ As, trimethyl-arsine; and, C2 H5 >• P, triethyl-phos- 
C Hi) C2H6) 
phine, are known. The alcohol radicals likewise combine 
with metals, such as zinc, tin, &c., to form bodies which in 
their turn combine with chlorine, &c., and have, therefore, 
been termed the organo-metallic radicals; such substances 
C H ) 
are zinc ethyl, Zn, and cacodyl, (C Hs)2 As. 
The following is a complete list of all the monatomic alco- 
hols and acids now known, giving their formulae, and boiling 
and melting points. In some cases the alcohol correspond- 
ing to a known acid has not yet been obtained ; a blank is 
then left in the alcohol series. Elementary Chemistry. 
249 
Monatomic Alcohols. ) ( Monobasic Acids. 
[■ yield } 
General formula Cn H2n + 20 ) ( General formula Cn H2n 02. 
Name. 
Formula. 
Boiling 
Point. 
Name. 
Formula. 
Boiling 
Point. 
Melting 
Point. 
Methyl .... 
c h4 o 
66° C 
Formic . . 
c h2 o2 
IOO° 
+ 1° 
Deutyl or Ethyl . 
C2 H„ 0 
7 8°-4 
Acetic . . 
c2 h4 o2 
Il8° 
+ 17° 
Trityl or Propyl . 
C3 H8 0 
96° 
Propionic . 
C3 Hs 02 
I400 
below 20° 
Tetryl or Butyl . 
C4 H10 0 
109° 
Butyric . . 
C4 Hs 02 
162° 
Pentyl or Amyl . 
C6 h12 0 
132° 
Valerianic , 
Cb H10 O2 
1740 
Hexyl .... 
C6 h14 o 
150° 
Caproic. . 
Cs Hi2 02 
199° 
+ s° 
Heptyl .... 
Cr H16 O 
164° 
CEnanthylic 
C7 Hi4 o2 
2190 
Octyl 
Cg h18 0 
180° 
Capric . . 
C8 Hjs 02 
236° 
+ 14° 
— 
— 
— 
Pelargonic. 
C3 H j s 02 
260° 
+ 18° 
Decatyl . . . • 
Cio h22 u 
212' 
Rutic . . 
Cio H20 O2 
— 
27°-2 
— 
— 
— 
Laurie . , 
c12 h24 o2 
— 
43°’6 
— 
— 
— 
Myristic . 
c14 h28o2 
— 
53°-8 
Cetvl 
Cis H34 0 
melt. pnt. 20 
Palmitic 
Cis h32 o2 
— 
62° • 
— 
— 
— 
Margaric . 
Cit H34 02 
— 
— 
— 
— 
— 
Stearic . . 
Lie H3s 02 
— 
69°-2 
— 
— 
— 
Arachic 
C20 H40 02 
— 
75° 
— 
— 
— 
Behenic 
C22 H44 02 
— 
76° 
— 
— 
— 
Hyaenic 
C25 H50 02 
— 
77° 
Ceryl 
C2t Has O 
melt. pnt. 79° 
Cerotic . . 
C27 Ha4 02 
— 
78° 
Melyl 
C'30 JHea O 
85° 
Melissic 
C3o Hso 02 
— 
88° Elementary Chemistry. 
250 
Monocarbon or Methyl Series. 
CH ) 
Radical Methyl, CH3. Methyl alcohol, com- 
monly called wood-spirit. It occurs in the dry distillation of 
wood, forming about one per cent, of the aqueous distillate ; 
it is likewise met with in the oil of winter-green, derived from 
the Gaultheria procumbens. Methyl alcohol can likewise be 
synthetically built up from its constituent elements, but only 
by means of several complicated reactions, which will after- 
wards be mentioned. 
Pure methyl alcohol is obtained from crude wood-spirit, in 
which it is contained mixed with a variety of other organic 
compounds, by forming a crystalline methyl oxalate ; this, on 
treatment with water, is decomposed, and yields the alcohol 
in the pure state. Methyl alcohol is a colorless, mobile li- 
quid, possessing a pure spirituous smell ; the specific gravity 
of the liquid is o-8i42 at o°, and its boiling point is 66°. It 
burns with a non-luminous flame, and is soluble in and mis- 
cible with water. Potassium dissolves in methyl alcohol 
with evolution of hydrogen and formation of potassium me- 
thylate, CHS q Methyl alcohol, when acted on by oxidiz- 
ing agents, yields formic acid ; no aldehyde of this series is 
known. By the action of bleaching powder on methyl alco- 
hol, chloroform is obtained ; acted upon by hydrochloric 
acid, the alcohol yields methyl chloride. 
The action of strong sulphuric acid on methyl alcohol is 
remarkable, and is the type of a general reaction. These 
two substances must be mixed with care, as great heat is 
evolved when they come in contact. The first substance 
CH.I O 
formed is hydric methyl-sulphate, cq ■> , by exchange of 
s' | 0 
hydrogen for methyl. When this body comes in contact 
with another molecule of alcohol, we have another ex- Elementary Chemistry. 
251 
change of hydrogen and methyl occurring ; but as this 
exchange can occur in two directions, we get either 
H ) H 1 CH3 ] 
S \ ° and SQj r °2> or TT r 0 and sos r °2: m the 
H ) a, CHS J 
first case, methyl ether and sulphuric acid; and in the 
second, water and di-methyl sulphate. 
Methyl Chloride, CH3 Cl, is obtained as a colorless gas, 
condensing at -20°, by acting upon methyl alcohol with 
hydrochloric acid or phosphoric penta-chloride; it is also 
formed along with other substances by the action of chlorine 
upon marsh gas. The bromide and iodide are colorless 
liquids, prepared by acting on methyl alcohol with bromine 
and iodine in presence of phosphorus. 
Methyl Hydride. Marsh gas, CHS H. As we have seen, 
this gas occurs in nature as fire-damp and the gas of marshes. 
It can be obtained easily by heating sodium acetate with 
caustic alkali; the acetic acid splitting up into carbonic 
dioxide and marsh gas, Ca H4 Oa = COa + CH4. Methyl 
hydride can also be obtained by passing the vapor of carbon 
disulphide, together with sulphuretted hydrogen gas, through 
a red-hot tube, and in this way it may be built up from its 
constituent elements. It may likewise be obtained by heat- 
ing methyl iodide together with zinc and water. Methyl 
hydride is a colorless inflammable gas, which burns with a 
slightly luminous flame, and when mixed with air produces a 
dangerously explosive gas. Most oxidizing reagents do not 
act upon this hydride, but chlorine attacks it in the presence 
of sunlight with such violence, as to produce an explosion. 
By the slow action of chlorine, several substitution products 
are formed, amongst the chief of which are—methyl chloride, 
CH3 Cl, chloroform, CH Cl3, and carbon tetra-chloride, C 
Cl4. 
Chloroform, CH Cl3, is formed by the action of chlorine on 
marsh gas, but it is prepared »by acting upon methyl or ethyl 
alcohols with bleaching powder. It is a mobile, heavy liquid, Elementary Chemistry. 
252 
possessing a powerful and agreeable smell; its specific gravity 
is i -525 at oc, and it boils at 62°. Chloroform is much used 
in medicine, producing, when it is inhaled, a temporary but 
perfect insensibility to pain, and is therefore much valued in 
surgical operations. Many other organic volatile bodies act 
in a similar manner, but none so effectually and so harmlessly 
as chloroform. An iodine compound, analogous to the pre- 
ceding, has been prepared; it is termed Iodoform, and is a 
yellow solid body. 
Carbon Teira Chloride, C Cl4, is a colorless liquid, boiling 
at 77°, obtained as the last product of the action of chlorine 
on marsh gas. When this substance is brought into contact 
with an amalgam of sodium and water, an opposite substitu- 
tion of hydrogen for chlorine occurs, marsh gas and all the 
intermediate products being formed. 
CH 7 
Methyl Ether, r O, a colorless and sweet-smelling 
gas at the ordinary temperature of the air; but condensing at 
-210 to a colorless liquid. It is prepared by heating the 
alcohol with sulphuric acid, as already described. 
Methyl Cyanide, C H3 CN or C2 H3 N, is obtained by the 
distillation of ammonium acetate ; thus, 
C2 H3 (NH4) 02 - H4 02 = C2 H3 N ; 
or by heating potassium methyl-sulphate with potassium 
cyanide. It is a colorless liquid, possessing a disagreeable 
smell, and boiling at 770. It is transformed into ethylamine 
in contact with zinc and dilute sulphuric acid, C2 H3 N + 
C H 7 
H4 = 2 j j6 >- N ; whilst acted upon by potash it forms 
acetic acid (see p. 274.) 
Methyl (EthylHydride), C2 Hfl. This substance is obtained, 
1st, by the action of methyl iodide upon zinc ; 2ndly, by the 
decomposition of potassium acetate by a galvanic current; and 
3dly, by the action of barium dioxide on acetic anhydride, thus : 
2(cl| H’o}°) + Ba°J='2 2Hs °2) Ba + Cs H# + 2 C O2 
Ace‘ c anhydride and barium ) .... ( Barium acetate and methyl and carbonic 
dioxide 1 yl61d ( acid. Elementary Chemistry. 
253 
This hydrocarbon was formerly supposed to be the free 
radical of the methyl group, but no methyl compounds have 
in any way been derived from it, whilst by the action of 
chlorine upon it, ethyl chloride, C2 H6 Cl, is obtained as the 
first substitution product. Hence we must regard methyl- 
and ethyl-hydride as identical. The nitrate, nitrite, cyanate, 
and sulphate of the 7nethyl series are also known. 
LESSON XXX. 
Di-carbon or Ethyl Series. 
The starting point of this important series is common—or 
ethyl-alcohol, Q H60 ; this is the ethyl hydrate, and, like its 
numerous derivatives, contains the radical ethyl, C2 Hs. 
Co H } 
Ethyl Alcohol, 6 >• O, is obtained in the vinous fer- 
mentation of sugar, a decomposition effected in aqueous sugar 
solutions in presence of yeast, in which alcohol and carbonic 
acid are chiefly formed ; the other products of fermentation 
are described under sugar (on p. 308). Alcohol can also be 
prepared from its elements by synthesis. This is done by 
obtaining acetylene (page 228), and combining this directly 
with hydrogen to form olefiant gas, Cs H4 ; this substance 
combines directly with strong sulphuric acid, forming hydrie 
ethyl-sulphate, C2 Hs) 
11 i 
SH°-}0 
and this, when boiled with water, forms sulphuric acid and 
alcohol by exchange of ethyl for hydrogen, thus; 
C2 H5 IO H) H [ O r w v 
so-1° + h(° = so.j0 + ’h|0' 254 
Elementary Chemistry. 
or, hydric ethyl-sulphate and water, yield sulphuric acid and 
alcohol. 
Olefiant gas also combines with hydric iodide to form ethyl 
iodide, which forms alcohol when heated with caustic potash. 
Alcohol and alcoholic liquids are prepared in large quan- 
tities by the fermentation of sugar derived from various 
sources. The fermented liquid is distilled, and the dilute 
aqueous spirit thus separated from non-volatile impurities ; 
it is obtained in a more concentrated form by repeated rectifi- 
cations, as it boils at a lower temperature than water. Alcohol 
cannot, however, be completely separated from water by simple 
distillation, the strongest spirit which can thus be prepared 
containing 10 per cent, of water. To withdraw all the water, 
the spirit must be distilled with some substance capable of 
combining with water, such as potassium carbonate or quick- 
lime. The pure liquid thus obtained is termed absolute alcohol: 
it is a colorless, mobile liquid, possessing a pleasant, spirituous 
smell and burning taste ; its specific gravity at o° is oSogs, 
and at I5°’5, 07939 ; and it boils at 78°‘4, when the barometer 
stands at 760 mms. It has not been solidified, becoming 
only viscid at a temperature of -ioo°. Alcohol is very inflam- 
mable, burning with a slightly luminous blue flame. It absorbs 
moisture with great avidity, and mixes with water in all pro- 
portions, the mixture evolving heat and undergoing contrac- 
tion. 
Many salts, as well as gases, dissolve in alcohol; it like- 
wise acts as a solvent for resins, organic bases, and essential 
oils, many of which do not dissolve in water. The determi- 
nation of the strength of spirit, when free from sugar or other 
soluble matters, is ascertained by determining the specific 
gravity by means of delicate hydrometers, and reference to 
accurate tables, showing the percentage of water. In these 
estimations the temperature must be accurately observed, 
and corrections for deviations must be made, as alcohol 
expands considerably with increase of temperature, and the 
specific gravity is thereby altered. The “ proof spirit ” of 
the Excise contains 50‘8 parts by weight of alcohol to of Elementary Chemistry. 
255 
water, and possesses a specific gravity of 0'g20 at I5°'5. 
Owing to the high duty on pure spirit, the Government allows 
the sale of a mixture of ninety parts of strong alcohol with 
ten parts of wood-spirit for manufacturing and scientific pur- 
poses ; this substance is called “methylated spirit,” and 
is most useful to the scientific and manufacturing chemist. 
Spirits, wines, and beer also contain more or less alcohol, 
flavored with certain essential oils, sugar, or extracts. 
Brandy, whisky, and the other spirits, contain from 40 to 50 
per cent, of alcohol; wines from 17 (Madeira and port) to 7 
or 8 (light claret and hock) per cent, whilst strong ale and 
porter contain from 6 to 8 per cent. 
Alcohol is decomposed when its vapor is passed through a 
red-hot tube ; hydrogen, marsh gas, olefiant gas, naphthaline, 
benzole, and other products being formed. By oxidation 
alcohol is transformed first into aldehyde and then into acetic 
acid. This oxidation may be effected by the atmospheric 
oxygen in presence of finely divided platinum, or more slowly 
when certain fermentable bodies are present (see acetic acid, 
p. 274). The alkaline metals attack alcohol with rapidity, 
evolving hydrogen, and forming potassium or sodium ethylate, 
C, h ) 
j/ 5 > O, Hydrochloric acid forms, with alcohol, ethyl 
chloride and water, and the corresponding bromine and iodine 
compounds act similarly. Strong sulphuric acid combines 
with alcohol to form hydric ethyl-sulphate, or sulphovinic 
acid, a substance which forms salts called the ethyl-sulphates ; 
C2 Hfi ) Q 
11 < 
thus potassium-ethyl-sulphate is SOa ) n 
K ]u- 
Ether, or Ethyl-Ether, > O. This important sub- 
stance is formed in a variety of ways from ethyl compounds. 
The most simple reaction by which ether can be prepared is 256 
Elementary Chemistry. 
that of acting upon potassium ethylate with ethyl iodide, an 
exchange of ethyl and potassium taking place, thus : 
C2 Hs I + C2 Hs ( T7- r , C2 H5 ) p. 
K I O - K I + c2 Hs ) 
Ethyl iodide and potassium ethylate give potassium iodide 
and ether. 
Another reaction by which ether is prepared on the large 
scale consists in heating a mixture of alcohol and sulphuric 
acid to 140°, when ether and water are given off. The decom- 
positions which here take place are as follows : in the first 
place, alcohol and sulphuric acid form hydric ethyl-sulphate 
(sulphovinic acid) and water, by an exchange of hydrogen and 
ethyl, thus : 
Hydric Ethyl 
Alcohol. Sulphuric Acid. Water. Sulphate. 
H I o C3 H5)q 
C2 H6) q „ } u _ H ) 0 „ } U- 
H [° + SO2 n “ h}° + SO2 I n 
H ju H > ' 
This hydric ethyl-sulphate next comes in contact with a 
second molecule of alcohol, another exchange of hydrogen for 
ethyl occurs, and ether and sulphuric acid are formed. 
Alcohol and Hydric Ethyl yield Ether and Sulphuric 
Sulphate Acid. 
Ca Hb ) n H ) 
C2 Hs ) Q , II \ C2HB ) /-v , II j O. 
h}U + SO2 ) n- C2Hs j 0 + SO2 
H J u f O. 
The water formed by the first decomposition, and the ether 
produced by the second, are given off as vapor, whilst the 
sulphuric acid remains behind, ready again to go through the 
same series of changes on meeting with two other molecules 
of alcohol. This process is called the continuous etherification 
process, as a current of alcohol may be passed continuously 
through the sulphuric acid heated to 140°, and a regular sup- 
ply of ether and water thus obtained. Elementary Chemistry. 
257 
Ether is a colorless, very mobile liquid, possessing a strong 
and peculiar etherial smell. It is lighter than water, specific 
gravity 0736, and is not miscible with this liquid. Ether 
boils at 34°'5, and its vapor is 37 times heavier than hydro- 
gen, and can be poured from vessel to vessel like carbonic 
acid gas. It burns with a luminous flame, and explodes 
when mixed with air. From its low boiling point great care 
must be taken to avoid explosions when working with this 
substance, owing to the vapor becoming mixed with air. 
Ether is easily attacked by oxidizing agents, yielding the 
same products as alcohol, and it is also acted upon by chlo- 
rine, and a large number of substitution products formed. 
Mixed Ethers containing two different radicals are ob- 
tained by acting, for instance, with ethyl-iodide upon potas- 
sium methylate, thus : 
Ethyl Iodide and Potassium ■ ,, Potassium and Methyl-Ethyl- 
Methylate e Iodide Ether. 
Ca Hs I + C H3 ) ir i , C Hs ) pj 
K \° ~ KI + C3H6}0’ 
CH3I 
or by acting on hydric methyl-sulphate, S02 > 02, with ethyl 
H ) 
alcohol. The following is a list of some of the more impor- 
tant simple and mixed ethers of this series : 
Table of Simple and Mixed Ethers. E“!ins 
Methyl Ether . . . C2 Ha O c Si j0 * * " 2I° 
Methyl-ethyl Ether . C3 H8 O C2 Ha [ 0 * • +11' 
Ethyl Ether. . . . C« Hi. O cl h! }0 * * 34° 
Methyl-amyl Ether . Ca Hia O | O . . 92° 258 
Elementary Chemistry. 
Ethyl-butyl Ether . . C6 Hi« O cl H." [ 0 ‘ * 8o° 
Ethyl-amyl Ether . . C7 Hi6 O cl H* | ® * * II2° 
Butyl Ether . . . . C. H18 O cl ill | 0 * * I04° 
Ethyl-hexyl Ether . C.H.sO Q hL [0 * • I32° 
Amyl Ether . . . . C,0 Haa O c! hI! | ° * * x76° 
Ethyl Chloride, C2 H6 Cl, is obtained as a mobile liquid, 
having an etherial penetrating smell, by saturating alcohol 
with hydrochloric acid gas, or by acting with the phosphoric 
chlorides upon alcohol. On heating the mixture a volatile 
liquid is given off, which must be condensed in a freezing 
mixture. Ethyl chloride boils at 11°. Ethyl iodide, C2 H6 I, 
and ethyl bromide, C2 Hs Br, are obtained by acting upon 
alcohol with iodine and bromine in presence of phosphorus. 
The iodide is much used for the preparation of other ethyl 
compounds, owing to the facility with which the iodine can be 
exchanged in double decompositions. It is a heavy, color- 
less liquid, boiling at 72°-2, and having a specific gravity of 
1'946 at 16 . 
Ethyl Cyanide, C2 H6 C N, is prepared by heating potas- 
sium ethyl sulphate with potassium cyanide. It may be con- 
sidered as a nitrogen compound (nitril) of the next higher 
carbon series (propyl), as on heating with potash it yields 
propionic acid, thus: 
Propionitril and Water yield Propionic Acid and Ammonia. 
CsHsN + 2 HaO = CsHeOa + NHS. 
Propionitril, when acted upon by hydrogen, yields propyl- 
amine; Ca H5 C N + 2 Ha = 3]q7 | N. This reaction is 
important, as it is one which is common to all the series of 
alcoholic cyanides, and enables us to pass from a lower to a Elementary Chemistry. 
259 
higher carbon series—in this case from the 2 to the 3 carbon 
series. 
Ethyl Hydride, Ca H5 H. This substance, already de- 
scribed as methyl, is a colorless and tasteless gas, obtained by 
the action of zinc and water upon ethyl iodide when heated to 
150° in a closed tube. It occurs in American petroleum. It 
is rapidly acted on by chlorine, and yields ethyl chloride, 
together with a series of further substitution products, the last 
of which is carbon chloride, Ca CI8. 
Ethyl Nitrite, Ca H6 N Oa, is obtained as a sweet-smelling 
liquid by acting upon alcohol with nitric acid, and it is con- 
tained in the “sweet spirits of nitre” of the Pharmacopoeia, 
r u ) 
Ethyl Nitrate, q6 > O, is only formed by the action of 
nitric acid on alcohol when urea is present, as this body 
immediately destroys any nitrous acid which may be formed, 
which would prevent the production of nitrate. 
Ethyl Sulphydrate, a y S. This compound, known as 
Mercaptan, is sulphur alcohol, i. e. alcohol in which the oxygen 
is replaced by sulphur. It is obtained by acting on potas- 
K ) 
sium-sulph-hydrate, jq r S, with ethyl chloride, ethyl and 
potassium changing places. Mercaptan, like alcohol, can 
exchange its typical atom of hydrogen for metals: it forms 
with mercury an insoluble compound. This body boils at 36°, 
and possesses the nauseous garlic-like smell, characteristic 
of all the organic sulphur compounds. 
C j-j i 
Ethyl Sulphide, jj6 V S. This compound in the sulphur 
series is analogous to ether in the oxygen series; it is 
obtained by acting on potassium sulphide, Ka S, with ethyl 
chloride. It is a colorless liquid, boiling at 91°, and posses- 
sing a strong, disagreeable odor. 
C2 H8 ) n 
Hydric Ethyl Sulphate, g q < or Sulphovinic Acid, is 
H (0, 260 
Elementary Chemistry. 
formed when alcohol and strong sulphuric acid are mixed. It 
acts as an acid, and forms salts in which the typical hydrogen 
is replaced by a metal. The ethyl sulphates of the alkalies 
and alkaline earths are soluble salts, and crystallize well. 
SO ) 
Di-Ethyl Sulphate, yj ) \ *s °^ta' by acting 
upon ether with sulphuric trioxide ; it is a body which decom- 
poses on distillation and on addition of water. 
Ethyl Phosphates are known: they correspond to the tri- 
basic alkaline phosphates in containing either i, 2, or 3 mole- 
cules of ethyl, replacing hydrogen in tribasic phosphoric acid. 
Thus we have: 
Diliydric Ethyl- Hydric Diethyl- Triethyl- 
Phosphate. Phosphate. Phosphate, 
in in in 
PO ) PO ) FO I n 
C2 Hs } Os 2 (Ca H6) !■ Os 3 (C. H.) \ 
Ha ) H ) 
II 
CO ) 
Ethyl Carbonate, 2 (c H ) ( O2, corresponding to sodium 
n 
CO ) 
carbonate, | can also be prepared. 
C N ) 
Ethyl Cyanate, q >• O, a colorless liquid, boiling at 
6o°, and possessing a powerful and irritating smell. It is 
formed by distilling potassium-ethyl-sulphate with potassium 
cyanate. In contact with caustic potash it forms ethylamine, 
thus : 
S:3>+Kh}o)= + c||o. 
Ethyl Borates and Silicates likewise exist. 
Ethyl, or Butyl-Hydride, C< Hi0. A substance having 
this composition, and formerly supposed to be the radical 
ethyl in the free state, is obtained by heating to 150° ethyl 
iodide with metallic zinc in a closed tube. From this body Elementary Chemistry. 
no ethyl compounds can in any way be prepared ; but 
upon treatment with chlorine it yields the chloride of the fom 
carbon radical, viz., C4 H9 Cl butyl chloride. Hence the so- 
called ethyl must be looked upon as butyl hydride,C4H9H. 
Tricarbon Series. Propyl alcohol | O, has 
been found in the last products of distillation of French 
brandies ; it boils at 96°, dissolves freely in water, but does 
not mix in all proportions. Propyl alcohol unites with 
C3 HT 1 Q 
sulphuric acid to form hydric propyl-sulphate, 
H f u 
The propyl compounds have not been much studied ; they 
closely resemble the foregoing ethyl series of bodies. Propyl 
alcohol, when oxidized, yields propionic acid (see p. 249). 
C H ) 
Tetra-Carbon Series. Butyl alcohol, 4 jj9 I O, Bu- 
tyl alcohol is found in the oily liquid obtained at the end of 
the distillation of spirits from the beet-root molasses. It 
boils at 109°, and resembles common alcohol in its proper- 
ties, as well as in those of its derivatives. The butyl, ether, 
chloride, iodide, nitrate, and other compounds, are known ; 
they are prepared in the same manner as the ethyl compounds, 
and possess no specially note-worthy properties. 
C H ) 
Penta-Carbon Series. Amyl alcohol, 5pjU > O. This 
alcohol occurs commonly as the chief constituent of the 
Fousel oil obtained in the manufacture of potato brandy, 
from which it is obtained by washing with water and subse- 
quent rectification. It is a colorless liquid, possessing a dis- 
agreeable, penetrating smell; it dissolves in alcohol and 
ether, but is not miscible with water. Amyl alcohol boils at 
1320, and solidifies at - 20°. Amyl alcohol, like the fore- 
going alcohols, forms, with sulphuric acid, hydric amyl-sul- 262 
Elementary Chemistry. 
phate, which yields double salts, called the amyl-sulphates ; it is 
also attacked by hydrochloric acid, amyl-chloride, CsHuCl, 
being formed. Amyl alcohol, in presence of oxygen and finely 
divided platinum, undergoes oxidation to valeric acid, thus : 
Amyl Alcohol Valeric Acid. 
C‘g“[o + 0, = Cs Hi*h | O + Ha O. 
Potassium and sodium can replace the typical hydrogen of 
this alcohol, forming potassium or sodium amylate. The 
iodide and bromide are prepared in the same way as the cor- 
responding ethyl compounds, with the substitution of amyl- 
for ethyl-alcohol. 
C H ) . 
Amyl Ether, £5j_fU £ O, is a colorless liquid, boiling at 
176°, obtained by the action of amyl iodide upon potassium 
or sodium amylate, thus :— 
Amyl Iodide and Sodium • _ Amyl , Sodium 
Amylate Slve Ether and Iodide. 
C.H..I +c‘«”[o = + Nal. 
Amyl Hydride, C5Hn H. This substance is a volatile 
liquid, boiling at 30°, obtained by heating amyl iodide with 
zinc and water ; it occurs, together with all the hydrides of 
this series of alcohol radicals, in American petroleum, and in 
the light oils from the distillation of coal. 
The mixed methyl-amyl and ethyl-amyl ethers, have already 
been mentioned. Amongst the compound amyl ethers, the 
C H ) 
acetate, j_j‘q > O, is prepared on a large scale, as it pos- 
sesses the peculiar odor of Jargonelle pears, and it is used in 
flavoring cheap confectionery. This compound is obtained 
by distilling amyl alcohol with potassium acetate and sulphuric 
acid; it can also be prepared by heating the chloride with 
potassium acetate. If this amyl acetate be heated with potash, 
amyl-alcohol and potassium acetate are formed. Elementary Chemistry. 
263 
Amyl and Potash give Amyl and Potassium 
Acetate Alcohol Acetate. 
c%"o 1° + h!° = Ch"(0 + c. k,0;°- 
Amyl, CI0 H22. A substance having this composition is 
obtained by acting on amyl iodide with sodium. It is a color- 
less liquid, boiling at 158°, from which none of the amyl com- 
pounds can be obtained, but which yields decatyl chloride, 
C10H21 Cl, on treatment with chlorine. We, therefore, con- 
sider this body as decatyl hydride, Ci0H21 H, and as not be- 
longing to the amyl group. 
Higher Alcohols. The alcohols containing 6 to 10 
atoms of carbon resemble the foregoing series in their general 
properties. Hexyl and heptyl alcohols are found in certain 
fermented liquors; octyl alcohol is obtained by distilling 
castor oil with potash. The hydrides of these, as well as of 
all the higher and lower alcohol radicals, are found in American 
petroleum. This substance consists essentially of a mixture 
of these various hydrides from C H4 (marsh gas), or even H2 
(hydrogen), up to hy*drides which are solid, and contain a 
very large number of atoms of carbon, and to which the name 
of Paraffine has been given. The hydrides can be separated 
from each other by repeated rectifications, and obtained in the 
pure state. From these hydrides the corresponding chlorides 
can be prepared by the action of chlorine, and from the 
chlorides we can form the acetates and the alcohols them- 
selves (see Amyl Acetate). 
C H ) 
Cetyl Alcohol, 16 jj33 [ O, is found combined with palmitic 
acid in spermaceti. It forms a white solid crystalline mass, 
but acts in its chemical properties like an alcohol; thus it 
forms a chloride, Ci6 H33 Cl, also a bromide and iodide; it 
C H ) 
likewise yields an ether, (-.18 pp33 i O, obtained by the action 
of cetyl iodide upon potassium cetylate ; and a compound with 
Lis Has ) 
sulphuric acid, S02 > 02. Cetyl alcohol undergoes oxida- 
H ) 264 
Elementary Chemistry. 
tion when heated with caustic potash, yielding an acid in 
which one of oxygen replaces two of hydrogen of the alcohol, 
thus : 
Cetyl Alcohol and Potash yield Potassium and Hydrogen. 
Palmitate 
Cie H33 | Q + K | q _ Cl6 K.i O | c + H4 
This palmitic acid bears the same relation to cetyl alcohol 
as acetic acid does to common- or ethyl-alcohol. 
C H r ) 
Cerotyl Alcohol, 27 jj65 £ O, is contained in Chinese wax ; 
it is a white solid solid, crystalline substance. When heated 
with potash it undergoes oxidation, and furnishes an acid, 
called cerotic acid, <~27 s3 | O. 
C U ) 
Melisyl Alcohol, 3°j|61 [ O, a solid white substance con- 
tained in beeswax: when fused with potash it forms an acid 
termed melissicacid,^80 59 ® | O. 
LESSON XXXI. 
Compounds of the Alcohol Radicals with the Ni- 
trogen (Triad) group of Elements. N. P. As. 
Sb. Bi. 
I. Compou7td Alcoholic Ammonias. The constitution 
C H ) 
of the primary monamines, as 1 h‘ | N, Ethylamine; se- 
condary monamines, as C2 H6 >■ N, Diethylamine ; and ter- 
H Elementary Chemistry. 
265 
C2H6) 
tiary monamines, as Triethylamine, C2 H6 }■ IT, have already 
C2H5) 
been mentioned (p. 248). These bodies are volatile; they all 
have a strong alkaline reaction and ammoniacal smell, and 
they combine with H Cl, &c., to form salts. These com- 
pound ammonias are formed in many ways, of which the 
most important are— 
1. By the action of caustic alkalies on the cyanates of the 
alcohol radicals (see p. 260). 
2. By the action of the iodides of these radicals on am- 
monia, we obtain the iodide of the compound ammonium, 
which, when treated by potash, yields the compound ammonia, 
thus, 
Ethyl Iodide and Ammonia give Ethylamine and Hydriodic 
Acid. 
(C2H5)> 
C2 H6 I + H >- N = H >N + HI. 
H> H ) 
Ethyl iodide acts similarly on ethylamine, giving rise to 
diethylamine and hydriotic acid, thus : 
C2 H61 + C2 H5, H2 N = (C2 H6)2 H, N + H I, 
and also acts upon diethylamine in the same way, giving rise 
to triethylamine, thus ; 
C2 H, I + (C2 H6)2 H N = (C2 H6)3 N + H I. 
Ethyl iodide also combines with triethylamine to form tetra- 
ethylammonium iodide, N (C2H6)41. In practice all these 
compounds are formed together when ethyl iodide acts on 
ammonia. The compounds of mono-, di-, and tri-ethylamine 
with hydriodic acid are decomposed by caustic potash, and 
the volatile compound ammonias liberated ; the case of the 
tetra-ethyl-ammonium iodide is different, as it is not decom- 
posed by potash, but yields, when treated with silver hydroxide, 
a hydrated oxide, which is non-volatile without decomj^osi- 266 
Elementary Chemistry. 
tion, and is analogous in constitution and similar in proper- 
ties to caustic potash. 
Tetra- ethylammonium 
Hydrate. Potassium Hydrate. 
g[o. 
By acting on ethylamine with other iodides, such as methyl 
iodide, mixed amines can be prepared. The compound am- 
monias form double salts with platinic chloride ; the larger 
the number of organic radicals contained, the more soluble is 
the platinum salt. The following table gives the names, com- 
positions, and boiling points of the most important of the 
compound ammonias. It will be seen that the boiling point 
increases with the increasing number of carbon atoms con- 
tained in the compound. 
Pri7nary Monamines. 
Boiling Point. 
CHS 1 
Methylamine H > N . . below o° 
H ) 
C2 Hs ) 
Ethylamine H > N . . i8°*7 
H ) 
CsH, ) 
Propylamine H >• N . . 490. 
C4 H9 'I 
Butylamine H > N . . 69° 
-H ) 
C6 Hu ) 
Amylamine H > N . . 940 
H ) 
Caproylamine, or 5” IN . . 126° 
Hexylamine • • • • • ( Elementary Chemistry. 
267 
Boiling Point. 
CT Hl5) 
Heptylamine H > N . . 146° 
H ) 
C8 Hit ) 
Octylamine H > N . , 170° 
H ) 
Secondary Monamines. 
CH, ) 
Dimethylamine .... C H3 > N . . 8o-5° 
H ) 
CH3 ) 
Methyl-ethylamine . . , C3 Hs > N . , — 
H 5 
Ca He ) 
Diethylamine . . . . . Ca Hs > N. . 570,5 
H ) 
C5 Hu ) 
Diamylamine C5 Hu > N . . 170° 
H ) 
Tertiary Monamines. 
CH3 ) 
Trimethylamine .... C Hi [ N . . 40—5° 
CH3 ) 
Ca Hs ) 
Triethylamine C3 Hs > N . . 910 
Ca Hs ) 
Ca Hs ) 
Diethyamylamine . . . . Ca HB > N . . 1540 
Cs Hu ) 
Cs Hu ) 
Triamylamine C6 Hu > N . . 2570 
Cs Hu ) 268 
Elementary Chemistry. 
Boiling Point. 
c H3 ) 
Methyl-ethyl-amylamine . C2 H5 > N ... 1350 
C5 Hn ) 
A comparison of these compounds shows that it is possible 
to have two or more bases of the same composition, but of 
different constitution ; thus C3H9N stands for methyl-ethyla- 
mine and trimethylamine. In order to determine the consti- 
tution of a body having this composition, it is necessary to 
ascertain how many atoms of the replaceable hydrogen of the 
original ammonia it contains. 
Phosphorus bases. Compounds corresponding to the pre- 
ceding, but containing phosphorus instead of nitrogen, have 
C2H6 I 
been prepared; thus, triethyl-phosphine, C2H6 > P, is ob- 
C2H6^ 
tained by acting upon zinc ethyl with phosphoric trichloride, 
the chlorine changing places with ethyl. 
Triethylphosphine is a colorless liquid, boiling at 127°*5, 
possessing a powerful and disagreeable smell. It combines 
directly with oxygen, sulphur, and chlorine, in this respect 
differing from the foregoing nitrogen bases. With ethyl 
iodide it combines and forms iodide of tetra-ethyl phospho- 
nium, P(C2H6)J, from which a strongly caustic hydrate, 
analogous to the corresponding nitrogen compound, can be 
obtained by the action of silver oxide (p. 265). 
Arsenic bases. The compounds of arsenic with the alcohol 
radicals differ somewhat in constitution from the foregoing, 
inasmuch as we are acquainted in the methyl series with (1) 
tri-methyl-arsine (CH3)3As ; (2) arsendimethyl (CH3)2As ; 
(3) arsen-monomethyl (CH3)As, The first of these is con- 
structed on the type ammonia, and the two latter combine 
directly with one and two atoms of chlorine respectively, and 
then form compounds belonging to the general type, NH3. 
We thus have the following compounds known : 
As H H H Arseniuretted hydrogen. 
As CH3 CH3 CH3 Trimethyl-arsine. Elementary Chemistry. 
269 
As CH3 CH3 Cl Arsendimethyl chloride. 
As GH3 Cl Cl Arsenmonomethyl dichloride. 
As Cl Cl Cl Arsenic trichloride. 
Trimethylarsine is a colorless liquid, boiling at 120°, formed 
by the action of methyl-iodide on an alloy of sodium and 
arsenic; it corresponds to trimethylamine and trimethyl 
phosphine. 
Arsendimethyl, or Cacodyl. This substance is prepared by 
heating arsenious oxide with potassium acetate. Cacodyl is 
a colorless liquid, boiling at 170°, which takes fire in contact 
with the air. It is extremely poisonous, and possesses a 
most disagreeable garlic-like smell, and must be prepared 
with great care. It combines with chlorine, oxygen, &c., 
and plays the part of an organo-metallic radical. One of the 
most important compounds is cacodylic acid, (C^3)21 02; 
it is soluble in water, and is not poisonous. The formation 
of cacodyl and its oxide in the mode described, may be used 
as a delicate test for the presence of arsenic, from the strong 
and characteristic odor of this body. 
Antimony bases. By acting on ethyl iodide with an alloy 
of antimony and potassium, a compound called tri-ethyl 
CaH, ) 
stibine, C2H5 >• Sb, has been prepared ; it is a colorless 
C2H5) 
liquid, boiling at 158°’5, which takes fire and burns in con- 
tact with the air. It forms compounds with oxygen, sulphur, 
and chlorine. 
Bistnuth forms an analogous compound, Triethbismu- 
C2H6 ) 
tine, C2H5 > Bi, Boron also unites with three molecules of 
C2H6^ 
ethyl to form a colorless liquid, which takes fire when brought 
in contact with air, and burns with a green flame. Elementary Chemistry. 
Compounds of the Alcohol Radicals with Metals. 
C H } 
Zinc Ethyl, qj_[5 >■ Zn. This important substance is ob- 
tained by the action of zinc upon ethyl iodide ; it is a colorless 
liquid, boiling at 118° ; it takes fire and burns with a green- 
ish flame in contact with air or oxygen, and forms zinc 
C-H ) 
ethylate, when the oxidation goes on slowly. Zinc 
Ethyl is a valuable reagent, by means of which many other 
compounds can be obtained : thus, if we act with this sub- 
stance on silicic chloride, we get zinc chloride and silicon 
ethylj on mercuric chloride, we obtain mercuric ethyl; on 
lead chloride, we get lead ethyl. Zinc methyl and zinc amyl 
are also known. Compounds of tin, lead, and a few other 
metals with the alcohol radicals, can be prepared, possessing 
properties somewhat analogous to the foregoing substances. 
Compounds of the alkaline metals with ethyl have been 
obtained by acting upon these metals with zinc ethyl. Sodium 
Ethyl combines directly with carbonic dioxide, and forms 
sodium propionate (p. 249), thus: 
Sodium Ethyl and Carbonic Dioxide yield Sodium Propionate. 
Na(C2H6) + COa = CsHUNaOa. 
LESSON XXXII. 
Compounds derived by Oxidation from the Alcohols. 
Group of Fatty Acids arid their derivatives. The mode 
in which the aldehydes and acids are connected with the cor- 
responding alcohols has been already described (p. 247). 
These oxidized products contain a radical in which one atom 
of oxygen is substituted for two of hydrogen in the alcohol 
radical. Elementary Chemistry. 
271 
H ) 
Thus we have on the type V in the di-carbon series— 
Aldehyde. Acetone. Acetyl Chloride. 
C2H30 ) C.HsO ) CaHaO ) 
H \ CHS ] Cl } 
and on the water type, \ O 
Hydric Acetate. Potassium Acetate. Ethyl Acetate. Acetyl Acetate. 
C2H3O ) n CaHaO) n C2H3O ) n C2H3O ) n 
HfU KfU Ca H6(U CaHaOj:0- 
If the typical oxygen of the water be replaced by sulphur, 
we get— 
Hydric Thiacetate. Potassium Thiacetate. Ethyl Thiacetate. 
C2H3O ) g C2H3O ) g C2H3O ) g 
H ) K ) CaHs ) 
Of the ammonia type we have the amides : thus— 
CaHaO ) 
Acetamide H > N. 
H J 
The following are the most important reactions, by means 
of which the monobasic acids can be obtained : 
1. From the alcohol having the same number of carbon 
atoms by direct oxidation. 
2. From the alcohol containing one atom less carbon, as 
follows: 
(a) By decomposition of the alcoholic cyanide by potash, 
ethyl cyanide yielding propionic acid (see p. 258). 
(b) By acting with the sodium compound on carbonic acid ; 
sodium ethyl and carbonic acid yielding sodium propionate 
(see p. 270). 
CHO ) 
Monocarbon Series. Formic Acid\ t O. This 
acid occurs ready formed in the bodies of red ants, whence 
its name; it is likewise found in stinging-nettles. Formic Elementary Chemistry. 
acid is obtained by the oxidation of methyl alcohol, as well as 
of sugar, starch, and other organic bodies. It is formed 
synthetically by acting upon potash with carbonic oxide gas 
at ioo°, thus: 
Carbonic Oxide and Potash yield Potassium Formate. 
CO + K10 = C K° [0 
Formic acid, diluted with water, can be best prepared by 
decomposing oxalic acid, in presence of glycerine and water, 
into formic acid and carbonic dioxide, thus : 
Oxalic Acid yields Formic Acid and Carbonic Dioxide. 
c2h2o4 = ch2o2 + co2. 
In order to obtain formic acid in the pure glacial state, free 
from water, the lead formate is decomposed by a current of 
sulphuretted hydrogen gas, and lead sulphide and formic 
acid are produced. Formic acid is a colorless liquid, possess- 
ing a peculiar sharp smell and strong acid taste. It boils at 
ioo°, and below i° it solidifies to a white crystalline mass ; 
its specific gravity at o° is i*235, and it is miscible in all pro- 
portions with water. Heated with sulphuric acid, it forms 
water and pure carbonic oxide gas, and oxidizing agents con- 
vert it easily into carbonic acid and water. A formate, 
heated with excess of baryta, yields oxalate, thus : 
Formic Acid yields Oxalic Acid and Hydrogen. 
2(CH2 02) = C2H204 + H*. 
Formic acid is monobasic ; and forms well-crystallizable 
salts called Formates: all the formates are soluble in water. 
It may be distinguished by its power of reducing metallic 
mercury and silver, as a gray powder, from the nitrates on 
boiling. 
CHO) 
Formamide, H y N. Obtained by acting on ethyl 
. H ) 
formate with ammonia. It is a colorless liquid, boiling at 
194°. The aldehyde of the monocarbon series is not known. Elementary Chemistry, 
273 
Dicarbon Series.—Acetyl Compounds. 
C u o) 
Aldehyde, a >■. Acetyl hydride is obtained by oxidi- 
zing dilute alcohol by means of a mixture of manganese diox- 
ide and sulphuric acid. It may also be prepared by distil- 
ling a mixture of an alkaline acetate and formate, thus : 
Potassium Acetate and Formate. Aldehyde. Potassium Carbonate. 
CsHsKOa + CHKO, = C2H40 + K2 C 02. 
It is a colorless, suffocating-smelling liquid, boiling at 21° ; 
it has a specific gravity of o-8oi at 0°, and mixes in all pro- 
portions with water, alcohol, and ether. Aldehyde reduces 
metallic silver, depositing it as a bright mirror from solutions 
of the nitrate, and this reaction may be used to detect the 
presence of the substance. It unites directly with nascent 
hydrogen to form alcohol, C2H4 O + H2 = C2 H6 O ; it like- 
wise forms acetyl chloride when treated with chlorine, and 
acetic acid when acted upon by oxidizing agents. Aldehyde 
is capable of existing in three other peculiar states, or of un- 
dergoing polymeric modifications. If it is preserved in con- 
tact with excess of acid it remains unchanged, but if it be 
pure it soon deposits a solid substance having the same com- 
position as aldehyde, and termed Metaldehyde; this sub- 
stance sublimes unchanged at 120°, but, when heated to 200° 
in a closed tube, it forms aldehyde again. Paraldehyde is an- 
other modification, and is a liquid boiling at 1240 ; and a 
third modification termed Acraldehyde, boils at no0. The 
molecular formula of paraldehyde appears to be, C8 HJ2 03, 
or 3 (C2 H4 O) ; that of acraldehyde, C4 H8 02, or 2 (C2 H4 O). 
Aldehyde is also isomeric with ethylene oxide (p. 283). 
Aldehyde forms a crystalline compound with ammonia, 
C H O 7 
termed Aldehyde-ammonia, 2 r > and it also unites with 
hydric sodium sulphite to form a solid compound. In 
many reactions aldehyde comports itself as the oxide of a 
11 
dyad, (C2H4) O. 274 
Elementary Chemistry. 
II 
C H 7 
Acetal, ,^3 >• 02. This substance is a derivative of 
(L2 ribja y 
11 
aldehyde, in which this dyad radical aldehydene, C2 H4, 
occurs. It is obtained by heating aldehyde and alcohol 
together, and is formed together with aldehyde when al- 
cohol is oxidized with sulphuric acid and manganese di- 
oxide. A compound of a similar constitution, viz., dime- 
II 
Co H ) 
thyl acetal, > 02, occurs in crude wood spirit. Acetal 
is isomeric with diethyl glycol (see p. 284). 
Chloral, Ca Cb O | -pjjjg substance may be considered as 
aldehyde, in which 3 of chlorine take the place of 3 of hydro- 
gen ; and although it has not been directly prepared from 
aldehyde, yet it resembles it in many properties, such as 
forming a crystalline compound with ammonia, which reduces 
silver salts. Chloral is obtained by the continued action of 
chlorine upon alcohol; it is a colorless powerfully-smelling 
liquid, boiling at 990. 
C H O ) 
Acetic Acid, 3 j^3 >-0. Dilute acetic acid has been 
known as vinegar from very early times ; it occurs in the 
juices of certain plants and vegetables, but only in small 
quantities. The most important modes of preparing acetic 
acid are: (1) the method generally practically employed by 
the oxidation of alcohol; (2) the theoretically interesting pro- 
cesses, 1st,—the direct combination of carbonic acid and 
sodium methyl, thus: 
C H, Na + C02 = Ca H, O ) n 
Na ) U ’ 
and 2d, by the action of potash on methyl cyanide, thus: 
CHaCN + 2 H20 = C2 Hs O | Q + N H>> Elementary Chemistry. 
275 
(3) Acetic acid is also prepared on a large scale by the dry 
distillation of wood; the crude acid thus obtained is com- 
monly called Pyroligneous Acid. 
Pure acetic acid is obtained by decomposing the acetates. 
The process by which alcoholic liquids (beer or wine) yield 
acetic acid by oxidation is termed the Acetous Fermentation 
(.see p. 313): the liquids are exposed to the air at a tempera- 
ture of about 250, for a fortnight, when the alcohol is changed 
to vinegar. This change appears to be brought about by the 
presence of a peculiar vegetable growth (mycoderma aceti) 
which floats on the surface of the liquid, first absorbing the 
oxygen, and then giving it up to the alcohol. 
Acetic acid in the pure state is obtained by heating sodium 
acetate with strong sulphuric acid: it is a colorless liquid, 
boiling at 1180 and solidifying to an ice-like mass at 17°, and 
hence the name of Glacial Acetic Acid has been given to it. 
It possesses a peculiar sharp smell, and has a strong acid 
taste ; it mixes in all proportions with water, but when dis- 
tilled the mixture has no definite boiling point; the residue 
becomes stronger until glacial acid remains. Acetic acid may 
be recognized by its smell, and by the formation of ethyl 
acetate ; also by the production of cacodyl when an acetate is 
heated with arsenious oxide. Acetic acid is monobasic, and 
forms a series of well-defined salts termed Acetates. The 
acetates of the alkalies are soluble crystallizable salts. 
Aluminium and ferric acetates are soluble compounds used in 
large quantities as mordants by dyers and calico-printers 
under the commercial names of Red Liquor and Iron Liquor. 
Lead acetate, or sugar of lead, and copper acetate, or verdigris, 
are the most important compounds of acetic acid and the heavy 
metals. The radicals methyl and ethyl, &c., can be substi- 
tuted for the atom of typical hydrogen in acetic acid forming 
the compound ethers (see a?ite, page 247). 
Acetyl Chloride, C2H3OCI, is obtained by the action of 
phosphoric oxychloride upon sodium acetate. It is a color- 
less liquid, fuming strongly in the air, and boiling at 550, 
The corresponding bromide and iodide are known. Elementary Chemistry 
C H O ) 
Acetyl Acetate, q >■ O, or Acetic Anhydride, is a 
colorless liquid, boiling at 138°, formed by the action of acetyl 
chloride, or phosphoric oxychloride upon sodium acetate, 
thus : 
4C2H302Na + POCU = 2(c2 nl O | 0 )+ PChNa. 
It is decomposed by boiling with water into two molecules 
of acetic acid. 
Chloracetic Acids. Chlorine acts upon acetic acid in re- 
placing one, two, or three atoms of the hydrogen of the radi- 
cal acetyl by chlorine: we thus obtain nionochloracetic 
acid\ <“2 Ha CIO | q . dichloracetic acid^'1 [ O j and 
c cl o ) 
trichloracetic acid, 2 3 > O. These three bodies are 
crystalline solids : the first fuses at 62°, and boils about 186% 
the second boils at 1950; and the third boils about 200°. They 
form salts analogous to the acetate ; and acetic acid may be 
regenerated from them by the action of nascent hydrogen. 
Thiacetic Acid, Hs O | This substance stands to 
acetic acid in the same relation as mercaptan to alcohol 
(p. 259) ; it is prepared by the action of pentasulphide of 
phosphorus on acetic acid. 
Pa Sb + 5 Oa Oa = I*2 Ob + 5 Oa H4 O S. 
It is a colorless liquid, possessing a peculiarly nauseous 
r u o ) 
smell, and boiling at 930. The anhydride, q [ S, is 
also known. 
C u o ) 
Acetyl Peroxide, jq3 q [ 02, is a remarkable compound, 
obtained by the action of barium dioxide upon acetic acetate. 
It is a thick liquid, possessing energetic oxidizing properties, 
and on heating it decomposes with explosive violence. Elementary Chemistry. 
2 77 
C2 H3 O 'I 
Acetamide, H > N, is the acetyl ammonia ; it is ob- 
H ) 
tained by the action of ammonia upon ethyl acetate by an 
exchange of acetyl for hydrogen, thus : 
&S:°jo +ii}N=c’i’0|N + “h.J0- 
It is also formed by the action of ammonia on acetyl 
chloride, and by the dry distillation of ammonium acetate. 
Acetamide is a colorless solid, fusing at 78°, and boiling at 
222°. 
C2 Ha O 1 
Diacetamide, C2 H3 O > N, and Ethyl-Diacetamide, 
H 5 
C2 Ha O 1 
C2 H3 O > N, are also known. Corresponding compounds 
C2 H5 ) 
are likewise formed from the chloracetic acids. 
C H O ) 
Acetone, t. This compound, which may be re- 
garded as methyl acetyl, is formed by replacing the chlorine 
in acetyl chloride by methyl, thus : 
C Hi [Zn + 2 (C’ H*C1 \ ) = 2 (C’ CH. 1 ) + cl- Z"- 
It is also obtained by the distillation of calcium acetate, or 
by passing the vapor of acetic acid through a red-hot tube. 
Acetone is a colorless liquid, boiling at 56°, forming, like 
aldehyde, a crystallizable compound with hydric sodium sul- 
phite. By the action of sodium amalgam on a mixture of 
water and acetone, 2 atoms of hydrogen are taken up, and a 
substance formed which is isomeric with propylic alcohol, 
thus (p, 261) : 
C3 Ho O + H2 = C3 H8 O. 
Acetylene, C2 H2. This remarkable substance is obtained 
by the direct combination of carbon and hydrogen at a very 278 
Elementary Chemistry. 
high temperature. For this purpose the carbon terminals of 
a powerful battery are brought together in an atmosphere of 
hydrogen ; acetylene is formed and precipitated in combina- 
tion with copper as a red powder, when the gas is passed 
through a solution of ammoniacal cuprous chloride. Acety- 
lene is formed in all cases of incomplete combustion of car- 
bon compounds, also when the vapor of alcohol is passed 
through a red-hot tube, and it is contained in small quanti- 
ties in coal gas. It is a colorless gas, possessing a peculiar 
and unpleasant odor ; it burns with a luminous smoky flame, 
and combines directly with chlorine and bromine. 
Higher Fatty Acids. The names, composition, and 
boiling points of these acids have already been given (p. 249). 
In their general characteristics they closely resemble the first 
two of the series, formic and acetic acid. They occur in 
many natural fats, and they are all formed by the action of 
nitric acid upon mutton or beef stearine (p. 305). 
These acids may be prepared synthetically by the following 
important reactions: (1) by the direct combination of car- 
bonic acid with the sodium compound of the next lower alcohol 
radical (p. 274); (2) by the action of potash on the cyanide 
of the next lower alcohol radical (p. 258) ; and (3) by replac- 
ing 1 or 2 atoms of hydrogen in the radicals of the fatty acids 
by alcohol radicals. They are most of them oily liquids 
slightly soluble in water, easily soluble in alcohol, and each 
forms a well-defined series of salts. The higher members of 
the series, especially palmitic and stearic, occur in all fatty 
bodies; they are solid substances obtained by decomposing 
soaps made from palm-oil or beef-suet, which consist of 
sodium or potassium palmitate and stearate {see Fats, p. 305). 
These acids form anhydrides, compound ethers, chlorides, 
aldehydes, amides and acetones, corresponding in constitu- 
tion and in general chemical characters with the same com- 
pounds in the acetyl series. For the description of the 
properties of these compounds a larger work on Organic 
Chemistry must be consulted. 
The general reactions of the group of monatomic alcohols Elementary Chemistry. 
279 
and acids which offer the greatest theoretical interest are, 
certainly, those by which it is possible, in the first place, to 
prepare the most simple terms of the series synthetically from 
their elements, and, secondly, to pass directly by addition of 
carbon and hydrogen from these lower terms to the higher 
ones, and thus to mount up the series. Suppose that we 
begin with methyl alcohol obtained from inorganic sources ; 
viz,: (i) Marsh gas prepared from sulphuretted hydrogen and 
carbonic disulphide, thus: 
2 SH3 •+• CS3 H” Cu8 — CH4 + 4 (Cu3 S). 
(2) Methyl chloride, from this by the action of chlorine, thus: 
CH4 + Cl3 = CH3 Cl + HC1. 
(3) Methyl alcohol, from this by the action of potash, thus : 
CH3 Cl + KHO = CH4 O + K Cl. 
There are now several modes by which we can pass to the 
dicarbon series :— 
(1.) From methyl alcohol we prepare methyl cyanide ; this, 
on decomposition with potash, yields acetic acid (see p. 275), 
thus : 
CNCH3 + KHO + H30 = C3 H3 K03 + NH3; 
we cannot directly reduce the acids to alcohols, but we can 
obtain aldehyde from acetic acid by distilling it with a formate 
(p. 273), thus: 
C3 H3K03 + CHKOa = C3H4 O +K3 C03; 
and from aldehyde we can obtain ethyl alcohol directly by the 
action of hydrogen (p. 273), thus : 
C3 H4 O + Ha = C3 H6 O. 
(2.) From methyl alcohol we prepare methyl cyanide, and 
by acting upon this with hydrogen, we get ethylamine (p. 
252), thus : 280 
Elementary Chemistry, 
C2 Ha) 
CNCHa + H4 = H N. 
H J 
Ethylamine acted upon by nitric trioxide yields ethyl nitrite, 
which, on decomposition with potash, yields the alcohol, thus : 
C2 Hi N + N2 Os = C2 Ha N02 + H2 O + N2 
and C2 Ha N02 + KHO = C2 H8 O + K N02. 
(3.) From methyl alcohol, by the action of zinc on methyl 
iodide, we prepare the so-called radical methyl: this sub- 
stance forms ethyl chloride when treated with chlorine ; from 
this we can pass through ethyl acetate to ethyl alcohol. The 
repetition of any of these three processes would enable us to 
pass to the tricarbon group, and so on. 
LESSON XXXIII. 
Diatomic Alcohols and their Derivatives. 
As we have seen (p. 229), the hydrocarbons of the general 
formula, C„ H2n, of which we may take ethylene, C2 H4, as an 
example, are non-saturated compounds, in which two of the 
combining powers of the carbon are not satisfied ; hence these 
bodies combine directly with two atoms of chlorine, bromine, 
&c., to form a saturated compound. The lowest term of the 
series, CH2, to which the name of methylene has been given, 
is not known in the free state, although its iodide, C H2 I2, 
has been isolated. The corresponding diatomic alcohol also 
has not been prepared, but the diacetate is known. 
Ethylene, C2 H4. This substance, known as olefiant gas, 
has already been mentioned (p. 78) ; it is formed in the dry 
distillation of coal and various organic bodies ; it is, however, 
best prepared by the action of hot sulphuric acid on alcohol; 
a mixture of 1 part of alcohol and 4 parts of sulphuric acid is Elementary Chemistry. 
281 
heated in a flask with enough sand to form a pasty mass. 
The decomposition is a very simple one; alcohol loses I 
molecule of water, H20, and ethylene is formed. The chief 
physical properties of ethylene have already been mentioned 
(p. 79). It combines directly with 2 atoms of chlorine, also 
with hydrochloric and hydriodic acids ; with chlorine it forms 
ethylene dichloride; with the hydracids it forms ethyl 
chloride, bromide, or iodide. 
II 
Ethylene dichloride, C2 H4 Cl2. Olefiant gas derives this 
name from its power of forming an oil when brought into con- 
tact with chlorine. On mixing these gases, drops are formed ; 
and when collected, washed, and distilled, they yield the pure 
dichloride, This body boils at 82°'5, and is insoluble in 
water, but soluble in alcohol and ether. It is rapidly attacked 
by chlorine, and substitution products are formed, in which 
one, two, three, and lastly, four atoms of hydrogen are re- 
placed by chlorine. Thus we have— 
Boiling Point. 
C2 H* Cl2 82°-s 
C2 H3 Cl Cl2 115° 
C2 h2 ci2 ci2 137 
C2 H Cl3 Cl2 154° 
C2 Cl8 182° 
From ethyl chloride a series of chlorine substitution pro- 
ducts are obtained, identical in composition, but differing in 
their properties from the foregoing; thus, the two sets of 
bodies boil at different temperatures ; whilst those from 
ethylene are decomposed by alcoholic potash, those from ethyl 
chloride remain unchanged. These two series of bodies are 
said to be isomeric. The last term, C2 Cl6, is identical in both 
series. 
n ) 
Glycol or Ethylene Alcohol, C2 H4 > 02. This substance, 
which may be supposed to be 2 molecules of water, in which 
2 atoms of the hydrogen are replaced by the dyad radical 282 
Elementary Chemistry. 
ethylene, is obtained by the action of ethylene dibromide upon 
silver acetate, silver bromide and glycol diacetate being 
formed, thus: 
Ethylene Di-bromide and Silver Acetate yield Silver and Glycol Diacetate. 
Bromide 
Ca He Bra + 2(C2a^3° | O ) = 2 Ag Br + C2 H3 ° 1 Oa. 
CtHi j 
The pure glycol is obtained from the acetate by acting on 
it with baryta. Glycol is a colorless, inodorous, and sweet- 
ish-tasting, thick liquid ; its specific gravity at o° is ri25, it 
boils at I97°'5, and it is soluble in all proportions in alcohol 
and water. When exposed to air in contact with water and 
platinum black, it absorbs oxygen rapidly, and is converted 
into glycolic acid, thus : 
Ca He Oa 4* Oa = Ha O -f- Ca He Os. 
Glycol, when heated to 240°, with caustic potash, gives off 
hydrogen and forms potassium oxalate, 
Ca He Oa + 2 K H O = Ca Ka Oe + 8 H. 
From these reactions it would appear that glycolic and 
oxalic acids stand to glycol as acetic acid does to ethyl alco- 
hol. Glycol likewise forms an aldehyde by loss of H4, the 
substance having the composition Ca Ha Oa, and called 
Glyoxal. Glycol acts like alcohol in other respects ; the 
typical hydrogen can be replaced by sodium, forming com- 
pounds analogous to sodium ethylate ; it also forms a com- 
pound with sulphuric acid, called glycol-sulphuric acid, 
II 
Ca He 
11 >- Os; and when heated with hydriodic acid, it forms 
SOa 
Ha 
ethylene iodide and water. Elementary Chemistry. 
283 
Glycol differs, however, from alcohol, inasmuch as it forms 
two acids, two chlorides, &c. Thus by the action of hydro- 
chloric acid on glycol, the first product obtained is glycol 
chlorhydrine, that is, glycol in which I atom of Cl takes the 
place of the monad group, HO ; whilst by the further action 
of chlorine a second replacement of the same kind occurs, 
and ethylene chloride is formed. 
(i) Glycol. (2) Glycol Chlorhydrine. (3) Ethylene Chloride. 
c2H4(o3 „ ” n 
Ha 1 Ca H4 ) '~l2- 
The first of these bodies is built on the type of 2 molecules 
of water, the second on a mixed type of 1 of water and 1 of 
hydrochloric acid, and the third on the type of 2 of hydro- 
chloric acid. There are also 2 acetates of glycol known, 
monoacetate and diacetate ; two ethyl compounds, mono- 
ethyl glycol and di-ethyl glycol: this latter body is isomeric 
with acetal (p. 274). 
11 
Ethylene Oxide, Ca H4 O. This substance is prepared by 
the action of potash on glycol chlorhydrine, which loses a 
molecule of hydrochloric acid and forms glycol ether. Ethy- 
lene oxide is a volatile colorless liquid, boiling at i3’5, soluble 
in all proportions in water. It does not form, like its isomer 
aldehyde, a crystalline compound with ammonia, but it com- 
bines readily with hydrogen, chlorine, acids, &c. Alcohol, 
Ca H8 O, is formed by the direct union of ethylene oxide with 
H2 ; and on oxidation glycolic acid is produced. 
Polyethylene Glycols may be represented as bodies con- 
structed on the type of 3, 4, 5, 6, &c,, molecules of water in 
II 
which several molecules of C2 H4 are substituted for the 
equivalent of hydrogen ; thus we have 
n ] 
C H 
Di-ethylene Glycol, Ca H4 ( 3* 
HaJ 284 
Elementary Chemistry. 
II 
c2 h4 
II 
Tri-ethylene Glycol, C2 H4 04. 
ii 
c3 h4 
hJ 
ii ' 
C3 H4 
II 
c3 h4 
Tetra-Ethylene Glycol, ” }■ 08. 
G2 H4 
II 
C3 H4 
hJ 
Ethylene Diamiftes. These are formed on the type of two 
molecules of ammonia, in which 2, 4, or 6 atoms of hydrogen 
are replaced by ethylene. We thus have primary, secondary, 
and tertiary diamines, corresponding to the monamines 
already described. They are volatile bodies obtained by the 
action of ammonia on ethylene dibromide. 
Higher Diatomic Alcohols and Derivatives. 
The higher carbon series yield olefines corresponding to 
ethylene. 
The following is a complete list of the olefines and glycols, 
as far as they have been prepared : 
Olefines. 
Boiling Point. 
Ethylene C3 H« 
Propylene C3 H6 
Butylene C4 Hg + 3° 
Amylene Cs H10 + 35° 
Hexylene C6 Hi3 + 69® Elementary Chemistry. 
285 
Boiling Point 
Heptylene C7 Hi4 + 95° 
Octylene C8 H18 + 116° 
$£$£) C- 
Cetene Cia H3a + 2750 
Carotene C27 H54 
Melene C3» H6o 
Glycols. 
Boiling Point. 
Ethyl Glycol j^4 | 02 I97°'S 
Propyl Glycol Ca j. 02 1880 
Butyl Glycol C4 j- 02 183° 
Amyl Glycol 1 02 177°* 
Hexyl Glycol Ce | 02 207° 
Octyl Glycol Cs | 02 237° 
Each of these combines with Cl2 to form a di-chloride, and 
each forms a glycol, from which an aldehyde and two acids 
can be obtained by oxidation. The olefines above ethylene 
yield compounds with hydrochloric and hydriodic acids, which 
are not identical, but only iso7neric, with the chlorides and 
iodides of the monatomic radicals. 
* We have here to notice the remarkable exception which the first four of the 
glycols exhibit as regards their boiling points'; in opposition to the general law, 
the higher carbon glycols boil at a lower temperature than those containing less 
carbon. 286 
Elementary Chemistry. 
LESSON XXXIV. 
Diatomic Acids, resulting from the Oxidation of 
the Glycols. 
These bodies belong, like the glycols, to the type of 
H- 7 
y Oa. There are two series of these acids, the first derived 
by the replacement of 2 atoms of hydrogen in the ethylene 
by 1 atom of oxygen, and the second by the replacement of 
all 4 atoms of hydrogen in ethylene by 2 atoms of oxygen. 
The first of these groups of acids may be termed the Lactic 
Acid Series, and the second the Oxalic Acid Series, from the 
substance best known in each. The relation of glycol to 
glycolic and oxalic acid, serving as a type of the general rela- 
tions, is seen in the following:— 
Glycol. Glycolic Acid. Oxalic Acid, 
n n n 
Ca H4 ") p. Ca Ha O | p. Ca Oa ) p. 
Ha ) °3 Ha ;°2 Ha \ °3‘ 
In like manner we have the following series of acids :— 
Type, Cn H2n—2O I Oa 
Ha f 
Name of Acid. Lactic Acid Series. 
11 
Carbonic Acid . . . CO ) n 
(Hydrate) Ha } Ua’ 
Glycolic . . . . Ci | Oa. 
Lactic Cs | Oa. 
Butylactic . . . | Oa. Elementary Chemistry. 
287 
Valero-lactic . . Cs Us£ | 02. 
Leucic . . . .CeH^|0a. 
Oxalic Series of Acids. 
Type, Cn H2n—4 02 ) 
Ha | 
Name of Acid. Formula. 
Oxalic. C* | 02. 
Malonic. C,H,hI|0,‘ 
Succinic. 4 | 02. 
Pyrotartaric. ("5 | 02. 
Adipic. Ca h-h; } °- 
(Unknown.) CtHi°22S|0’- 
Suberic. °- 
Azelaic. C9 Hl4 | 02. 
Sebacic. Ci°Hi8h2| °2- 
Rocellic. C"HMg;}0fc 
II 
CO) 
Carbonic Acid' / 0> This substance is only known 288 
Elementary Chemistry. 
in its salts, the hydrate not having been prepared. These 
ii 
salts may be supposed to contain the radical carbonyl., CO. 
Carbonic acid contains 2 atoms of replaceable hydrogen ; 
hence carbonates of the following composition are known : — 
CKa[°2’and Hk|°2 CaH? K ] °» and 2(C9H.) [ °’ 
Carbonic Oxide, C O (p. 76), is the isolated radical car- 
bonyl ; this substance combines directly with chlorine to form 
K ) 
chlor-carbonyl (phosgene gas), C O Cl2, and with > O, to 
COH ) 
form j/ y O, potassium formate. 
it 
CS ) 
Sulpho-Carbonic Acid, pj V S2. The potassium salt of 
this acid is obtained by the direct combination of carbonic di- 
sulphide (page 116) and potassium sulphide; and from this 
salt sulphocarbonic acid is prepared by the addition of hydro- 
chloric acid. A large number of derivatives of this body are 
■ . CS ) 
known : thus we have di-7nethylsulpho-carbonate, 2(QH ) r S2; 
CS ) 
hydric-methyl-suipho-carbonate, > S2. For a de- 
scription of the compounds intermediate between the sulpho- 
and the oxy-carbonates the larger manuals must be con- 
sulted. 
The acids of the first series above carbonic are monobasic, 
that is, they have only one atom of hydrogen replaceable by 
a metal, while those of the second series are dibasic, or contain 
two of hydrogen thus replaceable ; both series are diatomic. 
C H O ) 
Glycolic Acid, V 02. This substance is obtained by 
the oxidation of glycol; it may also be derived from the mon- 
atomic series of acids by the action of potash on mono-chlor- 
acetic acid, thus: Eleme7itary Chemistry. 
289 
Potassium Mono-chlor j and Potash Potassium Glycolate. 
c.H.aoj0 + Hja c.h.0£0i + kc1 
Glycolic acid forms a deliquescent crystalline mass, and 
forms salts called Glycolates, which contain only one atom of 
metal. An amide, called Glycolamide, is known, as well as a 
substance isomeric with it, termed Glycocolle. 
C O ) 
Oxalic Acid, > 02. Oxalic acid is met with in the 
juice of many plants in the form of potassium or calcium salt. 
It is formed in a great variety of ways, chiefly by the oxida- 
tion of different organic bodies. The best way of preparing 
pure oxalic acid is by acting upon sugar with nitric acid ; it 
has generally been manufactured in this way on a large scale, 
but at present it is prepared in very large quantities by the 
action of caustic potash on sawdust. Crude potassium oxalate 
is thus formed, and from this a pure oxalic acid is obtained by 
precipitating the insoluble calcium oxalate and decomposing 
this by sulphuric acid. Oxalic acid can also be prepared by 
the direct oxidation of glycolic acid. 
Oxalic acid crystallizes in prisms which possess the com- 
position Cs Ha O4 + 2 H3 O ; these crystals lose their water 
of crystallization at xoo°, or in vacuo over sulphuric acid. 
When heated to about 160° oxalic acid rapidly decomposes, 
forming carbonic acid, carbonic oxide, and formic acid, whilst 
a small quantity of oxalic acid sublimes undecomposed. 
Heated with sulphuric acid, oxalic acid is decomposed into 
water and equal volumes of carbonic acid and carbonic oxide 
gases (p. 76). Oxalic acid is a bibasic acid, and forms two 
classes of salts called Hydric Oxalates and Oxalates. The 
alkaline oxalates are all soluble in water; the oxalates of the 
other metals are generally insoluble. The potassium oxalates 
are ; 
C2 K2 O4 + H2 O. Potassium oxalate (neutral oxalate). 
C2 H K O4 + H2 O. Hydric potassium oxalate (binox- 
alate). Elementary Chemistry. 
290 
C2 H K 04 C2 H3 O4 + 2 H2 O. Acid potassium oxalate 
(quadroxalate). 
Calcium oxalate is a very insoluble salt, and is the form in 
which this metal is obtained for quantitative estimation. 
Methyl and ethyl oxalates are obtained by distilling the re- 
spective alcohols with oxalic acid ; the first boils at i6x°, and 
II 
r. o ) 
has the formula 02; the second boils at 1860, and 
II 
has the composition | 02, 
Oxalic Amides. By heating neutral ammonium oxalate, a 
white powder called Oxamide is left; the composition of this 
II 
C2 02 'j 
substance is H2 > N2, and it may be considered as being 
H2 ) 
2 molecules of ammonia, in which 2 atoms of hydrogen are 
n 
replaced by C2 02. By heating hydric ammonium oxalate, a 
substance called Oxamic Acid is obtained, having the formula 
gf* 
n belonging to a mixed type, one of water and one of 
C, o21 n 
H j u’ 
ammonia, in each of which one atom of hydrogen is replaced 
by the dyad C2 02. 
C H O ) 
Lactic Acid, 3 > Oa- This acid is contained in sour 
milk, and is formed from sugar by a peculiar change called 
the Lactic Fermentation ; an acid of the same composition is 
contained in the flesh of animals ; this is, however, not iden- 
tical with that, obtained by the fermentation of sugar,—hence 
the former is termed para-lactic-acid. It can also be formed 
artificially — 
(1.) By the direct oxidation of propyl glycol. Elementary Chemistry. 
291 
(2.) By the decomposition of mono-chlor propionic acid by 
alkalies. 
(3.) By allowing aldehyde, hydrocyanic acid, and hydro- 
chloric acid to remain in contact for several days. 
C, H.O + HCN + HC1 2(Ha O) = N H4 Cl + C3 H6 03. 
Lactic acid is a syrupy liquid of specific gravity 1-215, 
which cannot be distilled without decomposition, but, when 
heated, forms lactide (the anhydride), C3 Hl 02, and dilactic 
acid, Ca H10 05. When it is heated with hydriodic acid, 
lactic acid forms propionic acid. The lactates form a well- 
defined class of salts, containing as a rule one atom of metal— 
the other atom of hydrogen being replaceable only by an 
C3 H, O ) 
organic radical: thus we have ethyl-lactic acid, C2 H5 > 02, 
H ) 
forming also a definite series of salts. All the lactates are 
soluble in water and alcohol : the zinc lactate is the most 
characteristic of the salts ; it crystallizes in shining needles. 
Lactyl Chloride, C3 H4 O Cl2, is formed by the action of 
phosphorus pentachloride on calcium lactate. 
Lactamide, C3 LL 02 N ; lactic monamide is obtained by the 
action of ammonia on lactide. It is isomeric with alanine, a 
substance formed by the union of aldehyde, hydrocyanic acid, 
and water. 
The higher acids of the lactic series do not possess suffi- 
cient general interest to entitle them to consideration in an 
elementary work. We therefore pass to the higher acids of 
the oxalic series. 
Malonic Acid, C3 H4 Ot, is obtained by the oxidation of 
malic acid (p. 293) ; it is an unimportant substance. 
Succinic Acid.\ 02 | This acid is obtained by 
the distillation of amber ; it occurs in certain resins, and in 
small quantities in various animal juices, and it is produced 
by the fermentation of sugar (p. 308). It can be artificially Elementary Chemistry. 
prepared (i.) by the action of hydriodic acid upon malic and 
tartaric acids (p. 293). 
(2.) By action on ethylene di-cyanide by potash, thus : 
II 
C2 (CN)j + 4 H, O = C4 He 04 + 2 NHS. 
(3.) By the action of potash on cyanopropionic acid, thus : 
C3 H5(CN) 02 + 2 H2 O = C4 He 04 + N H3. 
(4.) By the action of nitric acid on butyric acid, thus : 
C4 He Os + 3 O ~ Hs O + C4 He O4. 
Succinic acid forms large colorless crystals, which fuse at 
1800, and begin to boil at 235the vapor decomposing into 
succinic anhydride and water. It forms a chloride as well as 
anhydride when heated with phosphorus pentachloride. 
Bromine substitution products are also known, viz., mono- 
brom-succinic acid, 4 | Os, and di-brom-succinic 
acid, 4 2 r2 | Oa ; these acids, when treated with 
water and silver oxide, are respectively converted into malic 
and tartaric acids. Succinic acid forms two classes of salts, 
and is bibasic ; the salts of the alkaline metals are soluble, 
and these form an insoluble brown precipitate with ferric 
salts. 
Succinic Anhydride, C4 H4 03, is also known. 
The ammonia derivatives of this acid are : 
C4 H4 O2} 11 
Succinajnide, Hs > Ns, and Succinimide, C4 H4 02 [- N. 
H3 ) H ) 
For the special properties of the higher carbon acids of 
this series, the reader must consult a larger work on the sub- 
ject. 
Connected with succinic acid very intimately are two acids 
of much importance, viz., malic and tartaric acids. Elementary Chemistry. 
293 
Malic Acid., C4 H6 05. This acid occurs in the juice of 
most fruits, from which it can be obtained; it can also be 
prepared by the substitution of H O for Br in monobrom- 
succinic acid (p. 292). Malic is a triatomic acid, but only 
two of the three typical atoms of hydrogen can be replaced 
by metal ; hence it is bibasic. The malates are soluble in 
water; malic acid itself crystallizes in needles. When 
malic acid is heated to about 1800 it loses H2 O, and is con- 
verted into a new acid, C4 H4 04, which exists in two iso- 
meric states, forming fumaric and vialeic acids. These sub- 
stances both unite directly with hydrogen and yield succinic 
acid, C4 He 04. 
Tartaric Acid, C4 H6 O0. Tartaric acid exists in the juice 
of many fruits (grape, tamarind, &c.); it is deposited as po- 
tassium salt during the fermentation of wine, and this salt is 
known as tartar. Several interesting isomeric conditions of 
tartaric acid exist; thus the ordinary acid possesses the 
power of turning the plane of polarized light round to the 
right, and therefore is termed Dextro-tartaric acid., whilst 
another form obtained from certain specimens of tartar does 
not affect the ray of polarized light in any way, and is said 
to be inactive. This inactive tartaric acid, termed Racetnic 
Acid.\ can be divided into the common, or dextro-tartaric, and 
a new acid possessing the opposite power of deviating the 
plane of polarization to the left, and hence called Levro-tar- 
taric acid. There also appears to be a fourth modification 
of this acid which is distinguished by being inactive like ra- 
cemic, but not capable of being split up into the two active 
varieties. The inactive variety of tartaric acid can be pre- 
pared artificially by the action of lime-water on bibromo-suc- 
cinic acid, C4 H4 Br2 04, each of the atoms of bromine being 
replaced by H O, and yielding tartaric acid, C4 H6 08. Tar- 
taric acid is also formed by the action of nitric acid on 
sugar of milk. 
Tartaric acid (dextro) crystallizes in large oblique rhombic 
prisms belonging to the monoclinic system, which dissolve 
easily in water. When heated to 180° it fuses and undergoes Elementary Chemistry. 
294 
decomposition, evolving a peculiar odor of caramel. In pres- 
ence of oxidizing agents tartaric acid is converted into car- 
bonic, formic, and oxalic acids ; and when fused with caustic 
potash it forms acetic and oxalic acids. When tartaric acid 
is heated with hydriodic acid for several hours it is first 
reduced to malic, and afterwards to succinic acid, by losing 
first one and then two atoms of oxygen. Tartaric acid is a 
bibasic acid, containing two atoms of typical hydrogen which 
can be replaced by metals ; hence there are two classes of 
alkaline tartrates ; thus we have— 
Hydric Potassium Tartrate } ~ „ rr, 
(Cream of Tartar) \ U K°6 
Potassium Tartrate . . C4 H i K2 08. 
Tartaric acid forms with antimony a remarkable compound 
termed Tartar Emetic; this compound may be considered 
as potassium tartrate, in which one atom of potassium is 
replaced by a monatomic radical, Sb O. We then have tartar 
emetic, C4 H, (Sb O) KOe. This body is obtained by boiling 
a solution of cream of tartar with antimonious oxide ; the 
oxide dissolves, and, on cooling, tartar-emetic is deposited in 
crystals. This salt is much used in medicine, and acts as a 
violent poison when taken in quantity. Tartaric acid and 
citric acid are largely used by the calico printer to act as a 
discharge or solvent for the mordant, thus giving white spots 
on a colored ground. 
Citric Acid., Ce H8 Or. This acid is tribasic, and it is found 
in the juice of the lemon, and occurs in many other fruits, 
together with malic acid. Citric acid obtained from these 
sources crystallizes in large colorless crystals, which dissolve 
very easily in water. Three series of citrates exist, in which 
one, two, or three atoms of hydrogen are replaced by metal. 
The citrates of the alkaline metals are soluble, those of the 
alkaline-earth metals, of lead, and silver are insoluble in 
water. Elementary Chemistry. 
295 
LESSON XXXV. 
Cyanogen Compounds 
We have already seen that a series of compounds exists 
containing a monatomic radical, CN, called Cyanogen ; many 
of these compounds may be arranged under the three types 
which we have employed for other organic bodies. Thus we 
have 
Type [ Type J O. 
HyAcT"iCcSS Cyanic Acid C“ } O. 
Cyanogen CN ) Sulpho-Cyanic CN ) Q 
Gas CN \ Acid H f 
Cyanogen CN ) 
Chloride Cl } 
H I CN ) 
Type H >• N. Cyanamide H > N. 
H ) H J 
The cyanogen compounds may also be considered as 
derivatives of ammonia ; thus cyanic acid acts in many cases 
II 
CO ) 
as if it were j_j- > N, and this group becomes connected with 
the oxalic acid series of bodies. The cyanogen compounds 
are remarkable for forming series of polymeric modifications ; 
thus we have CN Cl, and C3N3CI3; | O, and j- 0:>. 
Cyanogen, |. This substance is obtained by heating 
the mercury, gold, or silver cyanides ; it is found in small 
quantities in the gases of the iron blast furnace. Its proper- 
ties have already been mentioned (p. 84.) It is formed by the 
action of heat on oxamide, and ammonium oxalate, and is 
thus connected with the oxalic group, as cyanogen is oxamide, 296 
Elementary Chemistry. 
minus 2 molecules of water. Cyanogen forms with potash a 
mixture of potassium cyanide and cyanate. 
Hydrocyanic Acid., HCN. The mode of preparation and 
chief properties of this substance have already been men- 
tioned. This acid easily undergoes decomposition, and can- 
not therefore be kept for a length of time either in the pure 
state or in aqueous solution. It yields ammonium formate 
thus; HCN + 2 H2 O = | O, as methyl cyanide yields 
acetic acid (p. 252). With chlorine and bromine it yields 
cyanogen chloride and bromide. The best method of de- 
tecting hydrocyanic acid is founded on the formation of Prus- 
sian blue. To the liquid containing the acid a few drops of a 
ferrous and a ferric salt are added ; then excess of caustic 
soda ; and lastly, an excess of hydrochloric acid, the forma- 
tion of a deep blue liquid, from which a deep blue precipitate 
separates either at once or after a little time, indicates the 
presence of hydrocyanic acid. The presence of this substance 
may also be recognized by evaporating some of the solution 
on a watch glass with ammonium sulphide to dryness on a 
water-bath ; on adding a drop of ferric chloride, a deep red 
coloration of ferric sulpho-cyanide is produced, if hydrocyanic 
acid be present. 
The simple metallic Cyanides are formed by the direct 
action of hydrocyanic acid upon a metallic oxide; in addition 
to these a large number of double Cyanides are known. 
Potassium Cyanide, KCN, is formed when potassium is 
burnt in cyanogen or in hydrocyanic acid gas, or when potash 
is added to aqueous hydrocyanic acid. It is prepared on a 
large scale by fusing potassium ferro-cyanide (p. 297) with 
potassium carbonate. The iron is thus separated, and potas- 
sium takes its place. Potassium cyanide is a white salt, very 
soluble in water and hot alcohol ; it fuses easily without de- 
composition, and acts as a violent poison. Potassium cyanide 
is largely used in photography for dissolving the unaltered 
silver salts ; also in still greater quantity in the art of electro- 
typing in gold and silver, serving as a solvent for these metals. Elementary Chemistry. 
297 
The sodium and ammonium cyanides are also soluble, very 
poisonous salts. 
Mercuric Cyanide, HgC2N2, .is a soluble, easily crystal- 
lizable salt, formed by dissolving mercuric oxide in aqueous 
hydrocyanic acid. When heated it decomposes into gaseous 
cyanogen (C2N2), mercury, and a brown substance, isomeric 
with cyanogen gas, and called Paracya7iogen. 
The other simple cyanides are insoluble in water; amongst 
the most important is the white silver cyanide, and the 
brownish-red copper cyanide. In writing the formulae of these 
compounds, it is useful to express cyanogen by the symbol 
Cy. Amongst the numerous compound cyanides, those of 
potassium and iron are the most important ; in these the iron 
is contained in combination in a different mode to that in the 
ordinary iron salts, inasmuch as it is not precipitated from 
the cyanide solution by such re-agents as ammonia, or am- 
monium sulphide. The same remark applies to cobalt, and 
in a less degree to several other metals. 
Potassium Ferrocyanide, This salt, commonly 
called yellow prussiate of potash, is made on a large scale by 
heating nitrogenous organic matter with potashes and iron 
filings. On dissolving the mass in water, and evaporating 
the solution, large yellow quadratic crystals of potassium fer- 
rocyanide, containing 3 atoms of water of crystallization, are 
deposited ; it is not poisonous, acting as a mild purgative. 
When heated strongly, it yields potassium cyanide and iron 
carbide, and when treated with dilute sulphuric acid, hydro- 
cyanic acid is formed. By the action of strong and hot sul- 
phuric acid, the salt is decomposed, and carbonic oxide gas 
evolved. Solutions of this salt produce with ferric salts, a 
deep blue precipitate of Prussian blue, a ferric-ferrocyamde 
having the composition Fe4(FeCy6)s. With ferrous salts the 
yellow precipitate produces a white precipitate. 
Hydric Ferrocyanide, or F'errocyanic Acid, H 4 Fe Cy8. 
This acid is formed by adding hydrochloric acid to a strong 
solution of the foregoing salt. It acts as a strong acid, and is 
tetrabasic, forming a series of salts in which the four typical 298 
Elementary Chemistry. 
atoms of hydrogen of the acid are replaced by an equivalent 
of metal. 
Potassium Ferricyanide, K3 Fe Cy6. This salt, called red 
prussiate of potash, is obtained by passing chlorine gas 
through a solution of the yellow prussiate, which loses one 
atom of potassium ; the action must be allowed to continue 
until a drop of solution produces no blue precipitate with a 
ferric salt. On evaporation, the salt separates out in deep 
red prismatic crystals. This substance produces in solutions 
of ferrous salts a deep blue precipitate of Turnbull’s blue, 
Fes Cyia 
Fe3(FeCy6)2. 
Nitro-Ferrocyattides are a peculiar class of salts, obtained 
by the action of nitric acid on potassium ferro cyanide. The 
sodium salt crystallizes in red prisms, and produces with the 
slightest trace of an alkaline sulphide a deep purple color. 
Cyanogen Chlorides. Cyanogen forms with chlorine a 
chloride which exists in 3 polymeric modifications ; they are 
all obtained by the action of chlorine upon hydro-cyanic acid. 
Boiling Melting 
Point Point. 
Gaseous Cyanogen Chloride . Cy Cl — 120 - 150 
Liquid Cya CL I5°'S o° 
Solid Cy3 Cl3 190° 140° 
Cyatiic Acid, | O. The salts of this acid, termed cyan- 
ates, are readily formed by the direct oxidation of cyanides, 
and by the action of cyanogen gas upon potash. Cyanic acid 
itself cannot be prepared in the free state from its salts, as on 
liberation it at once changes into polymeric modifications 
called cyanuric acid and cyarnelide. It can, however, be 
obtained by heating cyanuric acid in a retort, and collecting 
the volatile cyanic acid in a freezing mixture ; it forms a 
colorless mobile liquid, but it immediately changes into solid 
cyarnelide when taken out of the freezing mixture. Cyanic 
acid in aqueous solution combines at once with water to form Elementary Chemistry. 
299 
ammonium carbonate, | O + H4 02 = NH4 H C03, and 
with ammonia to form urea, j-0 -f NH3 = CO N2 H4. 
Cyanic acid is a monobasic acid, 
CN ) 
Amjnonium Cyanate, > O, is formed by bringing to- 
gether dry ammonia and cyanic acid ; but this salt under- 
goes gradually at ordinary temperatures, and at once at ioo°, 
a remarkable molecular change, becoming urea, 
nh.}°= |°jN=- 
II 
ccn 
Urea, or Carbamide, H2 > N2. This important substance 
H.) 
is found in large quantity in the urine of mammalia, and in 
small amount in various animal juices. It is obtained arti- 
ficially—(i.) From ammonium cyanate, 
ii 
CO ) 
CN NR. O = H2 V N2. 
h2} 
(2.) By the action of ammonia on ethyl carbonate, thus : 
rn 1 Ha) PH) 
c° ? o2 + H2 [ n2 = h2 [ n2 + 2 u } o. 
2 (C. H.) f H2) H2) H > 
Ethyl Carbonate. Urea. Alcohol. 
(3.) By the action of mercuric oxide on oxamide : 
11 11 
c2 o2) CO ) 
H2 V N2 + Hg O = H2 f- N2 + C02 + Hg. 
h2 ) h2 ) 
Oxamide. Carbamide. 300 
Elementary Chemistry. 
The first of these methods is that by which urea is best pre- 
pared. For this purpose yellow prussiate of potash is mixed 
with manganese dioxide, and the mixture heated on an iron 
plate ; potassium cyanate is thus formed, and this salt is dis- 
solved in water and mixed with ammonium sulphate. On 
evaporating to dryness the urea can be extracted with alco- 
hol. Urea thus prepared crystallizes in long striated needles, 
which dissolve in their own weight of cold water, and to the 
same extent in hot alcohol. When heated to 120°, urea fuses 
and begins to decompose, forming substances termed amme- 
line and biuret; whilst at a higher temperature cyanuric acid 
is produced. When heated with water in closed tubes to 
ioo°, urea forms carbonic acid and ammonia, showing that it 
is an amide of carbonic acid. Nitrous acid decomposes urea 
instantly into carbonic acid, nitrogen, and water. Urea is 
the product of the oxidation of the nitrogenous constituents 
of the body, and the quantity of urea excreted is a measure of 
the activity of the changes going on. Urea forms com- 
pounds with acids and with bases. Urea nitrate and oxalate 
are the most important salts. With mercuric oxide, urea 
forms an important insoluble compound, which is employed 
as a means of estimating the quantity of urea in a solution. 
Compound Ureas. These compounds are formed by acting 
on cyanic acid with a compound ammonia. They may be 
considered as urea, in which one or more atoms of hydrogen 
are replaced by methyl, ethyl, &c. Compound ureas, con- 
taining the oxidized radicals, acetyl, butyryl, &c., are also 
known. 
Cya7iuric Acid., | 03. This polymer of cyanic acid is a 
solid crystalline substance formed on heating urea, or by 
acting with water on the solid cyanogen chloride. It is a 
tribasic acid, and is formed on the type of 3 molecules of 
water, 
Suiphocyanic Acid, | S. The potassium salt of this 
acid is easily prepared by heating potassium ferrocyanide Elementary Chemistry. 
301 
with sulphur ; on dissolving and crystallizing, potassium sul- 
phocyanide, | S, is deposited. The acid may be obtained 
by acting on mercuric sulphocyanide with sulphuretted hy- 
Cyanamide, H > N ; Dicya?tamide, CN > N ; and Tri~ 
H ) H ) 
CN ) 
cyanamide, CN > N, are obtained by the action of ammonia 
CN ) 
on cyanogen chloride. Several other amidic compounds of 
cyanogen exist, for description of which the larger manuals 
must be consulted. 
Uric Acid\ C5 H4 N4 03. This substance, found in the 
urine of birds, serpents, &c., is connected with the foregoing 
compounds. From uric acid a large number of derivatives 
have been obtained, amongst which may be named alloxan, 
C4 H . No O4 ; dialuric acid, C4 H4 N2 04 ; alloxatine, Ce H4 
N4 O7 ; and parabanic acid, C3 H2 N2 03 ; these derivatives 
of uric acid can be generally regarded as amides, containing 
the radical, C2 02, of oxalic acid. 
LESSON XXXVI. 
Triatomic Alcohols and their Derivatives. 
The hydrocarbon group having the general formula C„ 
H2ll—i, act in accordance with the views already expressed 
(p. 231) as triatomic radicals, to which the generic name of 
Glycerines has been given from the special name of one of 
in I 
the series, viz. C3H5 > 03. This substance is arranged on 
H3 ) 
the type of 3 molecules of water, and contains 3 atoms of 302 
Elementary Chemistry. 
typical hydrogen, each replaceable by a metal. From this 
formula it is clear that the possible number of derivatives of 
the triatomic alcohols is much larger than that of either of the 
preceding classes. The relation existing between the com- 
position of the mono-, di-, and triatomic alcohols of the same 
carbon series is a very simple one, as is seen by the follow- 
ing comparison of the three carbon series : 
C H ) 
Monatomic propyl-alcohol 3 > O, or C3 H8 O. 
11 ) 
Diatomic propyl-glycol, C3 H3 > 02, or C3 H8 02. 
Ho ) 
m } 
Triatomic propyl-glycerine, C3 H5 > 03, or C3 H8 03. 
H3^ 
The glycerines of the mono- and dicarbon series have not 
been prepared ; that of the tri-carbon series is best known 
and may be taken as the type ; amyl glycerine has also been 
prepared. 
m ) 
Glycerine, C3H5 V 03. This substance is contained in most 
H3^ 
oils and fats, both vegetable and animal, which consist of 
triatomic ethers of the higher terms of the fatty acid series ; 
thus beef suet, or stearine, is glycerine tri-stearate, or gly- 
cerine in which the 3 atoms of typical hydrogen have been 
replaced by 3 molecules of the radical, Ci« H35 O, of stearic 
acid (p. 249). Glycerine is also found in small quantities in 
the fermentation of sugar. Glycerine is formed from fats by 
the process of saponification, or treatment of the oil with 
caustic alkali, which decomposes the compound forming an 
alkaline stearate (soap), and liberating the glycerine which 
remains in solution when the soap is separated by throwing in 
common salt. In order to obtain pure glycerine the fat may 
be decomposed by lead oxide ; the glycerine remains in solu- 
tion, and tire lead-soap or plaister is precipitated. Another Elementary Chemistry. 
and better method is to decompose the fats with high pres- 
sure steam, free stearic acid and glycerine being produced. 
Glycerine is a colorless thick syrupy liquid, of specific 
gravity raB ; it possesses a very sweet taste (whence its 
name), and is soluble in water and alcohol. It can be dis- 
tilled in presence of aqueous vapor and in vaciio, but it under- 
goes decomposition when heated in the air. When mixed 
with dilute nitric acid, glycerine undergoes oxidation and 
r u a ) 
forms glycerinic acid\ 3 3 ( O3, by exchange of Ha for O ; 
this acid, therefore, stands to glycerine as acetic acid does to 
ethyl alcohol. Glycerine is reduced by hydriodic acid to iso- 
propyl iodide, thus ; 
Glycerine. Iso-propyl Iodide. 
C3 Hs O3 + 5 H I — C3 Hr I + 2 la + 3 Ha O* 
Propylglycol is also reduced to the same substance, and thus 
we can pass from the di- and triatomic series of alcohols to 
the monatomic series of iso-alcohols. 
If the nitric acid employed to act on glycerine be concen- 
trated, a new compound called Trinitrine, or Trinitro-gly- 
ceritie, is formed ; this is glycerine in which the 3 atoms of 
C Hr } 
typical hydrogen are replaced by N 02 ; thus, 5) t 3' 
This substance explodes violently when heated, and it is pro- 
posed to use it for blasting and other purposes. Heated 
with hydrochloric acid, glycerine forms compounds termed 
Chlorhydrines. These substances, of which there are three, 
are formed upon the mixed type of water and hydrochloric 
acid ; their composition will be easily understood by the 
following— 
Types. 
H3)0 HJ 0 
Hs \ °3 H, \ 0i H \ ° Hs Cl,. 
H Cl HaClj. 
303 Elementary Chemistry. 
304 
Glycerine. Chlorhydrine. Dichlorhydrine. Trichlorhydrine. 
in . Him H iO in 
C8 H6) n in I \ CL C3 H6 Cl,. 
II, \ Ua- CsHa S C1* Cs Ha ' 
Similar compounds are formed with bromine. 
The Acetic Ethers of Glycerine, or Acetines, are some of 
the best-known compounds of this alcohol; of these there are 
three, viz. : 
Mono-acetine. Di-acetine. Tri-acetine. 
C3 Ha / C3 Ha ) C3 Ha ) 
(C2HsOjH2 } 2(C3 Ha O) H \ 3(C, H3 O) ] Ua’ 
These substances, which resemble the fats in constitution, are 
obtained by acting upon glycerine with glacial acetic acid. 
They are thick oily liquids, only sparingly soluble in water, 
and boiling at a high temperature. 
The Stearic-, Palmitic-, and Oleic Ethers of Glycerine, or 
Stearines, Palmitines, and Oleines, are of great importance, 
as forming the natural fats. The stearines may be prepared 
artificially by heating glycerine with stearic acid. 
Monostearine. Distearine. Tristearine. 
C3 H6 ) n C3 H6 ) n C3 Ha ) n 
(Cl, H36 O) H2 \ Us- 2(C18HS60)H(Ul' 3(Ci8Hs5 O) £ Us‘ 
Tri-stearine can be obtained by melting beef or mutton 
suet, and separating the fibrous matter by filtration and crys- 
tallizing the stearine from solution in hot ether. It forms 
bright white shining plates, insoluble in alcohol and water, but 
readily soluble in ether. The melting point of stearine appears 
to undergo changes, and hence it is probable that this sub- 
stance is capable of existing in several distinct modifications. 
Similar glycerine-ethers have been prepared with many of 
the other members of the series of fatty acids. By the action 
of the mono-, di-, and tri-chlorhydrines upon sodium ethylate, 
the three ethyl-glycerine ethers, or ethylines, have been pre- 
pared ; these are— Elementary Chemistry. 
305 
Ethyline. Di-ethyline. Tri-ethyline. 
Ca He \ r\ C3 He ) /-> C3 He p. 
(C2H5) Ha f U3- 2 (C, H6)H \ Us- 3 (C, He)) U3‘ 
Poly-glycerines are known, corresponding to the polyatomic 
glycols (p. 283). Thus we have — 
C3HN C3H5) 
Di-glycerine, C3 H6 >• 03. Tri-glycerine CSH5 ( o 
H4) C3H5 f 
He J 
Natural Fats and Oils. The natural oils and fats are all 
compounds of glycerine chiefly with palmitic, oleic, or stearic 
acids, and they are contained in the bodies both of plants and 
animals. The fats cannot be distilled without decomposition, 
and when heated, give rise to a powerfully smelling substance 
called acroleine (p. 306). The oils are separated into the dry- 
ing and non-drying; the former become dry and resinous on 
exposure to air from oxidation, whilst the others remain 
unaltered. The drying oils are generally glycerides of acids 
not belonging, but nearly related, to the fatty acid series ; 
such, for instance, is the acid of linseed oil, called linoleic 
acid, Cie H.i8 O2: oleic acid, Ci# H34 02, is found in almost 
all oils and fats, the compound of this acid with glycerine con- 
stituting the liquid portions of the fats. 
When the oils or fats are acted upon by nitric acid they 
are decomposed, and the series of fatty acids formed. Fatty 
bodies when boiled with alkali undergo the remarkable 
change termed Saponification (p. 302); the fat is decom- 
posed into a fatty acid which combines with the alkali, and 
glycerine which is liberated passes into solution. Fats may 
also be saponified or separated into acid and glycerine by dis- 
tillation with steam alone. 
Allyl Cotnpounds. Intimately connected with glycerine 
are the compounds of a monatomic radical, C3 HB, called 
allyl. By the action of phosphorus iodide upon glycerine, 
a monatomic iodide, C3 H61, is obtained, from which a num- 
ber of bodies have been derived, whilst the acrid substance 30 6 
Elementary Chemistry. 
acroleine formed in the destructive distillation of glycerine is 
the aldehyde of this series. 
p II | 
Ally I Alcohol, 3 j^6 >■ O, obtaining by acting with ammo- 
nia on allyl oxalate. 
2(c! H.) } °*+ 2NH.= Cl || N. + 2 (c- H‘} O.) 
Allyl oxalate and ammonia yield oxamide and allyl alcohol. 
It is a colorless liquid, boiling at 103°, possessing a 
pungent smell. It is oxidized in presence of air and plati- 
num to acroleine and acrylic acid, which stand to this alco- 
hol in the same relation as aldehyde and acetic acid stand to 
C H O ) 
ethyl alcohol; thus acroleine is 3 V and acrylic acid 
C H O 7 
3 R3 I®' Sodium dissolves in allyl alcohol, forming 
sodium allylate, one atom of typical hydrogen in the al- 
cohol being replaced by sodium ; when this substance acts 
upon allyl iodide, an exchange of allyl and sodium takes 
C fj ) 
place, allyl ether, pj6 v O, being formed. The allyl sul- 
C H 7 
phide, £3 jq5 f S, is remarkable as occurring in nature as the 
essential oil of garlic, and the sulphide artificially prepared 
is identical in properties with the natural essence. In like 
C H- 7 
manner, allyl sulphocyanide, jh > S, is found as the essen- 
tial oil of black mustard seed. 
Tetkatomic Alcohols and their Derivatives. 
Tartaric and citric acids are tetratomic, but the former is 
bibasic and the latter tribasic. The only tetratomic alcohol 
as yet known is erythrite, a substance found in certain 
lichens and fungi ; its composition is C* H10 Cb, or it may be Elementary Chemistry, 
30 7 
H ) 
represented at jj* £ 04, in which four of hydrogen are re- 
IV 
placed by the tetratomic radical C4 H6. Treated with hy- 
driodic acid, erythrite forms iso-butyl iodide. The relations 
of these tetratomic compounds is seen by the following for- 
mula ; 
IV 
Erythrite, | 04. Tartaric acid,^^^2 | 04. 
Citric acid, | 04. 
Hexatomic Alcohols and their Derivatives. 
The best-defined member of this series is mannite, 
C6 Hi« Oa, which may be considered as 6 molecules of 
H ) 
water, j^6 £ 06, in which j6 atoms of hydrogen are replaced 
by a hexatomic radical, C6H8. Mannite is a solid, sugar- 
like substance contained in manna, the exudation from 
several species of ash. Mannite can be artificially prepared 
from certain varieties of sugar, which take up H2 when 
treated with water and sodium amalgam, C0 Hi2 06 + H2 = 
C6 H14 Oo. By oxidation of mannite, the reverse change 
occurs, and a fermentable,sugar, C6 Hi2 06, is produced : this 
change can also be effected by a peculiar ferment. The chief 
reasons for giving a hexatomic character to mannite are, (i) 
that when this substance is acted on by nitric acid, a com- 
pound, called nitro-7nannite, is formed, which is mannite con- 
taining the 6 typical atoms of hydrogen, replaced by N02 : 
VI ) 
thus its composition is C6 Hs >• Oe, and it is to be regarded 
6(NO.)) 
not as a substitution product, but as the nitrate of a hexatomic 
radical, which corresponds to ethyl nitrate in the monatomic 
series: (2) that mannite is attacked by hydriodic acid in a 3°8 
Elementary Chemistry. 
similar manner to glycerine (p. 302), and erythrite (p. 306), 
the monatomic iodide of the same number of carbon atoms 
being formed ; thus we have 
Ce H14 Os + II H I == Ce His I + 5 b b 6 Ha O. 
Mannite Iso-hexyl 
Iodide. 
In like manner the 6 of hydrogen can be replaced by 6 atoms 
of the radical of stearic acid ; we have then a compound 
VI ) 
mannite hexastearate, C6H8 > 06. 
6(C18H360) ) 
The substances having the composition of the iodides of 
the monatomic radicals, and obtained by deoxidation from 
glycerine (p. 302), erythrite (p. 306), and mannite, are isomeric, 
and not identical with these iodides ; they may be considered 
to be compounds of the olefine with hydriodic acid. By the 
action of silver oxide and water, the bodies yield a hydrate 
having the composition of the monatomic alcohols, but differ- 
ing from these in their boiling points, and in their chemical 
relations ; thus these so-called iso-alcohols readily yield the 
olefines from which they are derived, and, on oxidation, do 
not produce the corresponding acid, but form an acetone by 
loss of hydrogen ; indeed these iso-alcohols can be obtained 
by the action of hydrogen upon the acetones, thus— 
C3H9O + H2 = Cs H8 Oh. 
Acetone. Iso-propyl alcohol. 
LESSON XXXVII. 
Saccharine Bodies. 
These substances are frequently termed carbo-hydrates, in- 
asmuch as they contain hydrogen and oxygen in the propor- 
tion to form water, united with carbon. They form an im- Elementary Chemistry. 
309 
portant class of substances as occurring widely diffused in the 
bodies of plants. They may be divided into three classes ; 
(i) Sucroses, or the sugars proper ; (2) Glucoses, or the grape 
sugars ; (3) Amyloses, or starch and woody fibre. 
Each of these three classes contain several distinct sub- 
stances. 
I. Sucroses. 2. Glucoses. 3. Amyloses. 
C12H23O11. CeHiaOe. CeHioOs. 
Sucrose + Dextrose -t- Starch + 
(or cane sugar). (or grape sugar). Glycogene + 
Lactose -f- Levulose — Dextrine 
(or milk sugar). (or fruit sugar). Inuline — 
f Melitose ) Gums. 
< Melezitose > + Galactose. — Cellulose. 
( Mycose. ) Tunicine. 
The most important distinguishing physical property of 
these bodies is their action on polarized light. Like tartaric 
acid (p. 293), and many other substances, these saccharine 
bodies possess the power of turning the plane of polarization, 
some to the right-hand and some to the left: thus dextrose, 
or grape sugar, turns it to the right, levulose, or fruit sugar, to 
the left. The right-handed substances are marked in the 
preceding list with a +, the left-handed with a —. 
Sucroses. Sucrose, or Cane Sugar, C12H22O11.—This im- 
portant substance occurs in the juice of certain plants, espe- 
cially the sugar-cane, beetroot, mallow, and sugar-maple; 
also, in smaller quantity, in honey and various kinds of fruit, 
together with a mixture of dextrose and levulose. Sugar is 
prepared from the sugar-cane, which contains about 18 per 
cent, of sugar, by crushing out the juice by passing the cane 
between rollers ; the juice is at once heated to about 6o°, and 
a small quantity of milk of lime added for the purpose of 
precipitating the albuminous matter derived from the cane, the 
presence of which renders the juice liable to quick fermenta- 
tion. The juice is then raised to the boiling point, the scum Elementary Chemistry. 
which rises to the surface removed, and the clear liquid 
remaining is boiled down in copper pans until it attains a 
certain consistence, when it is filtered through linen bags, and 
again evaporated to a syrup, which, on cooling, deposits 
crystals of moist or brown sugar. The mother liquor is again 
evaporated, and again allowed to cool and deposit another 
crop of crystals ; the dark-colored, uncrystallizable sugar is 
termed molasses, or treacle. The refining of sugar is a pro- 
cess conducted chiefly in England. The raw sugar is dis- 
solved, and again boiled with lime and filtered. The filtered 
liquor is then decolorized by flowing through a thick bed of 
animal charcoal, and the colorless filtrate evaporated down to 
the point of crystallization, under diminished pressure, in 
vacuum-pans. The object of this is to enable the syrup to 
boil at a lower temperature than it would do under the ordi- 
nary pressure, and thus to prevent formation of uncrystal- 
lizable sugar, and to avoid the charring and coloring of the 
syrup which then takes place. The concentrated syrup is 
then either allowed to crystallize in moulds, giving loaf sugar, 
or the small crystals are freed from adhering mother liquor 
by quick drying in a hydro-extractor, or rapidly revolving 
sieve. Much saving is attained by the use of the vacuum- 
pans, and if its employment were universal in the colonies, 
where the sugar is first prepared, the formation of much 
treacle, or uncrystallizable sugar, would be avoided, and the 
profit to the planter proportionately increased. A method of 
treating the cane-juice has lately been proposed, which bids 
fair to revolutionize the manufacture of raw sugar. It 
depends upon the fact, that by a peculiar plan of rapid eva- 
poration, the whole of the water can be got rid of, without 
charring the sugar, which is thus obtained as a solid mass, 
and all formation of treacle avoided. 
Sugar crystallizes in monoclinic prisms, which phospho- 
resce when broken: its specific gravity is i*6o6. It is so- 
luble in one-third of its weight of cold, and in rather more of 
hot, water, and is nearly insoluble in alcohol and ether. * Its 
specific power of rotation is 73°8' to the right. Sugar melts Elementary Chemistry. 
at i6o° to a colorless liquid, which solidifies on cooling to a 
colorless transparent mass (barley-sugar), and, on standing, 
becomes crystalline and opaque. When more strongly 
heated, water is given off, and a dark colored mass, called 
caramel, is left behind. When acted on by nitric acid, either 
saccharic or oxalic acid is formed, according to the strength 
of the acid and the heat employed. Strong sulphuric acid 
converts sugar into a black mass, with evolution of sulphuric 
dioxide. A mixture of these two acids in the cold acts on 
sugar to form a nitro-substitution product, C12H18 
an amorphous mass, liable to explode on percussion. Solu- 
tions of sucrose easily reduce the noble metals from their 
solutions on warming, whilst cupric salts are only slowly de- 
composed in alkaline solution of sucrose. Cane-sugar is not 
directly fermentable, but, in presence of yeast, it takes up a 
molecule of water and forms a mixture of dextrose and levu- 
lose, both capable of undergoing fermentation :— 
C12H22O11 + H2O = + CoHi20g. 
Sucrose. Dextrose. Levulose. 
By the action of dilute sulphuric acid, the same change 
is produced ; and also by long continued boiling of a 
solution of sugar. Sucrose combines with certain metal- 
lic oxides to form definite compounds ; thus we have 
C12H 22O11 CaO, whilst other metals replace some of the 
hydrogen of the sugar ; thus lead forms a compound 
having the formula C^HisPbiOn. 
Lactose, or milk sugar, occurs only in the milk of mam- 
malia, from which it is obtained in the crystalline state by 
evaporation. The crystals, which are rhombic, contain an 
atom of water of crystallization, given off at 140°. Lactose 
dissolves in 6 parts of cold and 2 parts of boiling water; it 
does not possess nearly so sweet a taste as sucrose, and feels 
gritty in the mouth, and its specific power of rotation is 
+ 59°3'. Lactose does not ferment itself, but when much 
yeast is added, fermentation occurs, after some time, mannite 
being formed. In presence of cheese, &c., the lactic fer- Elementary Chemistry. 
312 
mentation sets in. Dilute acids convert lactose into a pe- 
culiar glucose, called galactose, which is directly fermentable, 
and yields mucic acid when treated with nitric acid. Lactose 
reduces an alkaline copper solution in the cold, precipitating 
cuprous oxide; but the quantity of this substance formed is 
not so great as when the same weight of glucose is employed. 
Lactose, when oxidized, yields mucic, saccharic, tartaric, and 
oxalic acids. 
Glucoses, Dextrose, or right-handed glucose, 
grape- or starch-sugar, is found in many kinds of fruit, in 
manna and honey mixed with levulose, or left-handed glu- 
cose. It forms a normal constituent of blood, white of 
egg, and exists in small quantity in healthy urine, whilst 
it is excreted in large quantities in that liquid in the disease 
termed diabetes. 
Dextrose is formed in many ways. 
(i.) By boiling starch or dextrine with diluted acids. 
(2.) By the action of malt upon starch (see Dextrine). 
(3.) By the action of dilute acids upon sucrose (when it is 
formed together with levulose. 
(4.) By the action of acids upon many glucosides. 
Dextrose is prepared by boiling starch with dilute sulphuric 
acid, adding chalk to neutralize the acid, and evaporating the 
liquid to a syrup when the sugar crystallizes. It may also 
be easily prepared by washing honey with dilute alcohol; the 
levulose being more soluble is thus removed. Dextrose turns 
the plane of polarization to the right: its permanent rotation- 
power is +56°. It is soluble in its own weight of water, and 
dissolves easily in dilute alcohol, and is not nearly so sweet 
as sucrose ; the crystals contain one molecule of water, 
which they lose at 60°. Dextrose immediately precipitates 
red cuprous oxide from alkaline cupric solutions ; and the 
quantity of dextrose present in a solution can be ascertained 
by employing a standard solution of alkaline copper salt. 
From silver salts the metal is deposited by dextrose, in the 
form of a mirror. Nitric acid oxidizes dextrose to saccharic 
or oxalic acid. Elementary Chemistry. 
313 
Levulose, or left-handed glucose. This forms an incrystal- 
lizable colorless syrup ; it is more soluble in water and alcohol 
than dextrose, and is therefore sweeter. Its action on po- 
larized light changes remarkably with the temperature : thus 
at a temperature of iq’C. its rotatory power is io6°, whereas 
at 90°C. it is reduced to 53°. Levulose reduces cupric salts 
like dextrose; it is obtained by neutralizing with lime the 
mixture of glucoses obtained by the action of sulphuric acid 
on sucrose. The levulose lime-compound is a solid, whilst 
dextrose forms a liquid substance. By decomposing this 
lime-compound with oxalic acid pure levulose is obtained. 
The acids having the composition CeHi0 08 (mucic and 
saccharic) obtained by the action of dilute nitric acid on the 
different sugars, must be regarded as products of oxidation 
of mannite, the hexatomic alcohol : levulose yields mannile 
when acted on by nascent hydrogen, and hence stands to this 
substance as aldehyde to alcohol. 
Mannite, 8 j^|8 i 06. 
Co Ho 7 Co He O ) n Co H4 Oa ) 
He ; Oo- Ho \ °6• Ho \ °6- 
Levulose. Mannitic Acid. Mucic and Saccharic Acids. 
Alcohol, C’ ( o. 
Aldehyde. Acetic Acid. 
Fermentation. This name has been given to a peculiar 
and interesting class of decompositions, which have long 
been known, but differ altogether from the ordinary chemical 
actions. Many organic bodies are capable of undergoing 
fermentation in presence of certain complicated substances 
termed ferments, giving rise to several products differing ac- 
cording to the nature of the fermented body and the ferment. 
Careful investigation has shown that the process of fermenta- 
tion entirely depends upon the presence and growth of cer- Elementary Chemistry. 
tain living organisms forming the ferment. Different kinds 
of ferments give rise to different products. Thus we have 
one ferment (yeast) which effects the alcoholic fermentation, 
another which sets up the lactic fermentation, a third produ- 
cing the acetous fermentation, &c. Most of these ferments 
are vegetable growths of a low kind, but one at least, viz., 
that causing the butyric fermentation, is an animal; and this, 
strange to say, cannot live in contact with free oxygen, but 
flourishes in an atmosphere of hydrogen. In order that the 
ferment should grow, it must be supplied with proper food, 
especially with ammoniacal salts and alkaline phosphates ; 
these are contained in the albuminous matter generally 
present in the liquid about to be fermented. In order that 
the fermentation should go on well, the temperature should 
be from 2oc to 40° ; at much higher, as at much lower tem- 
peratures, the vitality of the ferment is destroyed. 
In many cases, spontaneous fermentation sets in without 
the apparent addition of any ferment: thus wine, beer, milk, 
urine, &c., when allowed simply to stand exposed to the air, 
become sour or otherwise decompose. These changes are, 
however, not effected without the presence of vegetable or 
animal life, and are true fermentations ; the sporules) or seeds 
of these living bodies, always float about in the air, and on 
dropping into the liquid begin to propagate themselves, and 
in the act of growing evolve the products of the fermentation. 
If the above liquids be left only in contact with air which has 
been passed through a red-hot platinum tube, and thus the 
living sporules destroyed; or if the air be simply filtered by 
passing through cotton wool, and the sporules prevented from 
coming into the liquid, it is found that these fermentable 
liquids may be preserved for any length of time without un- 
dergoing the slightest change. 
The following are the five principal forms of fermenta- 
tion : 
1. The alcoholic fermentation, producing chiefly alcohol 
and carbonic acid. 
2. The acetous fermentation, producing acetic acid. Elementary Chemistry. 
315 
3. The lactic fermentation, yielding chiefly lactic acid. 
4. The butyric fermentation, yielding chiefly butyric acid. 
5. The mucous fermentation, giving rise to gum and man- 
nite. 
Alcoholic Fermentation. The glucoses are able, when dis- 
solved in presence of yeast, to undergo fermentation, evolv- 
ing mainly alcohol and carbonic acid,— 
Cs H12 Os = 2 C2 He O 4" 2 CO2. 
About 6 per cent, of the glucose undergoes a different 
change, part being used as nourishment for the yeast, and 
another part forming glycerine and succinic acid. From 100 
parts of glucose about 3-5 parts of glycerine are produced, 
and o‘6 to 07 of succinic acid, whilst i-2 to 1-5 parts of cel- 
lulose and fatty matter are formed by the growth of the 
yeast. The alcoholic fermentation occurs best at a tempera- 
ture of between 250 and 30°. 
LESSON XXXVIII 
Amylaceous Bodies and Gums. 
Dextrine, C8 Hi0O6. This substance, called British Gum, 
is prepared by heating starch to about 150° ; if a small quan- 
tity of nitric or hydrochloric acid is added to the starch, the 
transformation takes place much more rapidly. Dextrine is 
also formed together with dextrose by the action of malt 
extract upon starch. It deviates the plane of polarization 
strongly to the right, its rotatory power being + I38°7'. Dex- 
trine is very soluble in water and insoluble in alcohol, and 
on boiling with dilute acids dextrine is converted into dex- 
trose. 
Gum Arabic. The natural exudation from several species 316 
Elementary Chemistry. 
of acacias ; it consists chiefly of the potassium and calcium 
salts of arabic acid, C12 H2o O10. 
Inulin. A substance contained in the roots of many 
plants ; it is intermediate between gums and starch ; it yields 
levulose when boiled with dilute acids. 
Glycogen, or Animal Starch, is an insoluble powder 
formed in the liver and placenta; it is easily converted into 
glucose. 
Starch, C8Hio06 (or some multiple of these numbers). 
This important substance exists most widely diffused through- 
out the vegetable world. It consists of a white powder 
composed of granules which have a distinctly organized 
structure, and are of various sizes. The following are the 
diameters of the granules of some of the most important 
varieties of starch : 
Potato o'185 mm. Wheat . . o'o5omm. Millet . o'oiomra. 
Sago . “ Indian corn “ Beetroot C004 “ 
Starch granules are insoluble in cold water, alcohol, and 
ether, but when they are heated with water to between 70° 
and 72° they swell up and split open, forming a thick mass 
called Starch Paste. If this paste be boiled with a larger 
quantity of water, the particles of starch become so finely 
divided that the}' pass through a filter, and if boiled for a 
length of time, the solution becomes clear, and the starch is 
rendered soluble ; and from this solution alcohol precipitates 
a white amorphous powder of soluble starch. When heated to 
1600 starch is converted into dextrine. Starch, in its insoluble 
and soluble modifications, forms with free iodine a deep blue 
compound, the color of which is destroyed a little below 100 
but appears again on cooling. This color is characteristic 
of starch, and is not produced with dextrine or the other 
isomers of starch. When the soluble azotized matter con- 
tained in malt, called diastase, acts upon starch, it forms 
dextrine and dextrose ; and by a longer action the dextrine is 
also converted into dextrose. Elementary Chemistry. 
317 
3 (Co Hio Os)-)- H2 O — C12 H20 O10 + Ce H12 Og, 
Dextrine. Dextrose. 
The action of dilute sulphuric acid upon starch is similar 
to that of diastase. Strong sulphuric acid in the cold dis- 
solves starch, forming a compound acid ; nitric acid also dis- 
solves starch, and on adding water to the solution a white 
substance called xyloidine is precipitated ; this is a substitu- 
tion product, being starch in which one atom of hydrogen is 
replaced by N 02, thus : Ci2 Hi0 (NO?) Oi0. 
Cellulose, C6Hio06. This is the colorless material of the 
woody fibre of young plants ; it may be obtained in the pure 
state from cotton or linen fibre by boiling out the impurities 
with alkali, alcohol, ether, &c. Cellulose is a white substance 
insoluble in water, alcohol, or ether, but dissolving in an am- 
moniacal solution of cupric oxide. By the action of strong 
sulphuric acid, cellulose is converted either into an insoluble 
substance which colors blue with iodine, or into a soluble body 
like dextrine ; if this acid solution be diluted with water and 
boiled, dextrose is formed by fixation of one molecule of 
water. A useful substance is obtained under the name of 
parchment paper, by dipping sheets of paper into strong sul- 
phuric acid. 
Gun Cotton. The action of strong nitric acid upon cellu- 
lose is interesting; if cotton wool be thrown in small por- 
tions at a time into a mixture of equal volumes of strong 
sulphuric and nitric acids, it does not undergo any apparent 
change, but on drying it is found to be very inflammable. It 
is a substitution product, being cellulose in which two or 
more atoms of hydrogen are replaced by (N 02) thus : 
CgH8(N 02)20s. By the action of ferrous chloride nitric 
oxide is evolved and cellulose again formed. The use of 
gun-cotton as a substitute for gunpowder has been proposed, 
as it offers many advantages :— 
(i) The explosive force of gun-cotton is, weight for weight, 
greater than that of gunpowder. (2) The products of com- 
bustion of gun-cotton, being chiefly carbonic acid and nitro- 318 
Elementary Chemistry. 
gen, are not so apt to foul the gun. (3) When moistened it 
becomes inexplosive, and only requires drying to render it 
again explosive. 
The reasons which render the general adoption of this sub- 
stance doubtful are (1) its liability to explode on percussion ; 
(2) the possibility of its spontaneous decomposition when 
kept for a length of time. 
Gun-cotton, or certain forms of this substance, dissolves 
readily in a mixture of ether and alcohol, and yields a solu- 
tion which is termed Collodion, and is largely used for the 
purpose of forming a thin coating on glass to receive silver 
salts, upon which the photographic image is formed. 
Group of Glucosides. 
The numerous substances constituting this class occur in 
the bodies of many plants, and yield a glucose on decomposi- 
tion, together with other bodies ; they may be considered as 
kinds of compound ethers of glucose. The most important 
are amygdaline, salicine, and tannine. 
Amygdaline, C20H27NOn + 3 H2 O. Found in bitter al- 
monds, and obtained by dissolving out by alcohol, and preci- 
pitating the amygdaline with ether; it forms small white 
crystals which are soluble in water. The most remarkable 
decomposition which amygdaline undergoes is that which is 
brought about in the bruised almond by the presence of an 
albuminous substance called Synaptase, by which bitter al- 
mond oil, hydrocyanic acid, and glucose, are produced :— 
C20 H2T NO„ + 2H2 O = C, H6 O + H CN + 2Ce H„ 05. 
Amygdaline. Hydride of Hydrocyanic Glucose. 
Benzoyl. Acid. 
Salicine, Ci3 Hi8 O7, contained in the pith of the willow 
and poplar, and also found in the castoreum contained in a 
gland of the beaver. Salicine crystallizes in bright white 
needles ; it is soluble in water and alcohol, but insoluble in Elementary Chemistry. 
319 
ether, and its solution possesses a strongly bitter taste. In 
presence of certain ferments it is decomposed as follows : 
CisHieO? + H2 O = C7 HsOa + C8 Hu Oe. 
Salicine. Saligenine. Glucose. 
Tannine, or Tannic Acid, C27 H22 O17. This substance is 
contained widely diffused in certain parts of plants ; it is- 
distinguished by forming an insoluble compound with gelatin, 
and by producing a black color (ink) with ferric compounds. 
Tannic acid occurs in largest quantities in gall-nuts (an ex- 
crescence formed on the oak by an insect) ; it is extracted by 
aqueous ether from the powdered gall-nut. Tannine thus pre- 
pared is an uncrystallizable mass, soluble in water and alco- 
hol, but insoluble in pure ether. Tannine forms glucose and 
gallic acid when it is exposed to the air, or when treated by 
dilute acids. 
C27 H22 O17 + 4 H2 0 = 3 C7 H8 Os + C* Hu 0$ 
Tannine. Gallic Acid. Glucose. 
Tannine heated to 2150 yields pyrogallic acid. 
LESSON XXXIX. 
It has already been stated that in these bodies the carbon 
atoms are more closely combined together than is the case in 
the foregoing group, or, in other words, that the aromatic 
hydro-carbons contain relatively less hydrogen than those 
which we have hitherto studied. Another peculiarity of these 
substances is, that they contain at least 6 atoms of carbon, 
and that the more complicated compounds split up into those 
containing 6 carbon atoms. It appears in fact that all the 
aromatic bodies contain a group of 6 carbon atoms, in which 
18 of the combining powers of the carbon are taken up by 
The Group of Aromatic Compounds. 320 
Elementary Chemistry, 
union of carbon with carbon (p. 232), whilst 6 remain open to 
saturation. 
The simplest combination amongst the aromatic series is 
that of benzol, C6 H6, and from this body a large number of 
other substances can be derived by substitution of one or 
more atoms of hydrogen by more or less complicated mole- 
cules. Thus, for instance, we are acquainted with four hydro- 
carbons homologous with benzol but differing by C H2; these 
substances are in fact benzol, in which 1, 2, or 3* atoms of 
hydrogen have been replaced by methyl, C H3. We thus 
have : 
Boiling Point 
(1) Benzol . . . . C6 H« 82s 
(2) Toluol, or ) tt TJ ,ru \ 
Methyl-Benzol j C7H*, or C6H5(CH3) in 
(3) Xylol, or Di- ) r- tt or C H i CH3 no0 
methyl Benzol \ UHi„, or j CHa 139 
<4> CnSyl Belzil 1 C-H- or C'H' | .68* 
Each of these methylated benzols yields an important 
series of derivatives, corresponding to those obtained from 
benzol. Thus in each, one or more atoms of hydrogen can 
be replaced (i) by chlorine, giving chlorine substitution pro- 
ducts ; (2) by the monad N02 yielding nitro-substitution pro- 
ducts ; (3) by the monad N H2 yielding amido-compounds ; 
or (4) by the monad HO yielding a peculiar set of alcohol-like 
bodies, termed Phenols, as well as a series of true alcohols, 
isomeric with the phenols. The following table gives the 
names and formulae of some of the derivatives of benzol, and 
methyl-benzol, or toluol:— 
Benzol C6 H« 
Monochlor-benzol . CB Hs Cl 
Nitro-benzol . . . C6 H6 (N02) Elementary Chemistry. 
321 
Amido-benzol, or ) ~ mu \ 
Aniline } * C» H* (NH=) 
Phenol, or Car- > r n ,um 
bolicAcid | • C°H*(H0) 
Toluol C, Hs, or C6 H5 (CH3) 
Monochlor-toluol . . C7 H7 Cl, or C6 H4 Cl (CH3) 
Nitro-toluol . . . C7 H7 N02, or.C6 H4 (NO.) (CH3) 
Amido-toluol, or > XT XT TT /mu \ ! 
Toluidine | • Ct H» N> or C• H< (NH0 CCH0 
Cressol C7 He O, or C6 H4 (HO) (CH3) 
A series of bodies, isomeric with these toluol compounds, 
exists, in which the substitution takes place with the hydro- 
gen of the methyl. This is termed the Benzyl series. 
Toluol. Benzyl Chloride. 
C7 He, or C6 He (CH3) C7 H7 Cl, or C6 H6 (CH2 Cl) 
Benzylamine. 
C7 H7 ) C6 He (CH2) ) 
H N, or H N. 
H ) H ) 
Benzyl Alcohol. 
C’W’}0, or C. Hi (Ca.) | o. 
By oxidation benzyl alcohol yields an aldehyde, C7H6 O, oil 
of bitter almonds, and an acid, C7 Hr, 02, benzoic acid., both 
derived from this alcohol, as ethyl aldehyde and acetic acid 
are derived from ethyl alcohol. 
The di- and tri-methyl benzols also furnish similar double 
series of isomeric derivatives. In like manner all the higher 
alcohol radicals, ethyl, propyl, butyl, &c., can be substituted 
for one or more atoms of hydrogen in benzol, and thus an 
almost unlimited number of isomeric bodies may be pre- 
pared ; thus ethyl benzol, C6 H5 (C2H6), is isoitteric, but not 
f CH 
identical with di-methyl benzol or xylol, C6 H4 -j • 322 
Elementary Chemistry. 
Benzol, C6 H0. Found in the light oils obtained by the 
destructive distillation of coal; it is a colorless liquid, refract- 
ing light powerfully, boiling at 82°, and freezing at —4°-5. It 
is also obtained by distilling benzoic acid with slacked lime. 
Benzol is attacked by chlorine, and several chlorides formed ; 
when treated with nitric acid, an interesting substance called 
nitro-benzol, C6 H5 (NO,), is produced, a substitution pro- 
duct in which one of hydrogen of benzol is replaced by N Q»; 
and we also know a solid substance called di-nitro-be7izol, 
C6 H4 2 (NOj). In contact with reducing agents, nitro-ben- 
zol undergoes the following important reduction to aniline, in 
which the monad group (NOj) is replaced by the monad 
(N H,), thus : 
C„ H6 (NO,) + 3 H, = Ce H5 (NH,) + 2 H, O. 
Nitro-benzol. Aniline. 
Phenol, or Carbolic Acid’ C6 H5 (HO). This is a white 
solid crystalline body, fusing at 35and boiling at 1880, found 
in the heavy coal-oils. It dissolves in the alkalies, forming a 
phenate, but it does not possess an acid reaction. The most 
important property of this body is its powerful antiseptic 
qualities, and it is much used as a disinfectant, both alone 
and when combined with lime. 
Monochlor Benzol, Ca HB Cl, is formed by the direct action 
of chlorine on benzol, or when phosphorus penta-chloride 
acts upon phenol. 
Picric Acid, C6 H3 (N03)s O. When phenol is acted upon 
by nitric acid, 1, 2, or 3 atoms of hydrogen may be substi- 
tuted by NO,. Tri-nitro carbolic acid, or picric acid, is a 
bright yellow crystalline body, very soluble in water ; it is 
obtained by the action of nitric acid upon many other sub- 
stances besides carbolic acid and its derivatives. Picric acid 
is employed in the arts as a yellow dye for silk and woollen 
goods. 
Aniline, or Amido-benzol, C8 H5 (NH,). This important 
body is benzol, in which one atom of hydrogen is replaced by 
the monad group (NH,), and it is, therefore, properly called Elementary Chemistry. 
323 
Amido-benzol. The mode of preparing aniline from benzol 
has just been described, the reduction of nitro-benzol being 
generally effected by a mixture of iron filings and acetic acid. 
It may also be obtained by the action of potash on isatine 
(p. 328). 
C8 H6 N02 + 4 (KHO) = C9 H7 N + 2 (K9 COa) + Ha. 
Isatine. Aniline. Potassium Carbonate. 
It is also found amongst the products of the destructive 
distillation of coal. 
Aniline is a colorless liquid, possessing a peculiar smell ; 
its specific gravity at o° is i'036, and it boils at 185°. It is 
nearly insoluble in water, but dissolves in alcohol and ether ; 
it unites with acids to form definite salts, but it does not turn 
red litmus paper blue. Crude aniline is manufactured now on 
a very large scale for the preparation of the so-called aniline 
colors, so generally used in calico-printing, and woollen and 
silk dyeing. The smallest trace of aniline may be easily 
detected by adding to an aqueous aniline solution an aqueous 
solution of an alkaline hypochlorite, when a splendid red col- 
oration is formed: this is prepared in quantity by adding to 
aniline sulphate a dilute solution of potassium bichromate. 
This substance forms one of the important aniline colors, and 
is called mauve; it contains a base of complicated constitu- 
tion, termed mauveine. The color mauve can be prepared by 
many other methods ; the best of these is by heating aniline 
with a double chloride of sodium and copper. The other 
coloring matters derived from aniline are noticed on the next 
page. Ar iline gives rise to a very large number of deriv- 
atives ; thus we have a series of compounds in which one or 
more atoms of hydrogen are replaced by ethyl and other 
radicals. We are also acquainted with di-amido benzol, thus : 
C« H6 (NH„) C8 H4 2 (NHa) 
Aniline or Amido-benzol. Di-amido-benzol. 
C8 Hal 
Aniline has been called Phenylamine, H > N, but it can- 
H ) Elementary Chemistry. 
324 
not be prepared like an amine ; and it is therefore better to 
regard it as an amido substitution product. 
Benzylic, or Toluic Series. Toluol, or Methyl-benzol., 
C7 Ha = C8 Ha (CH3). This hydrocarbon occurs likewise 
in the coal-oils, and it boils at mc; it is also formed by the 
distillation of toluic acid with excess of lime. It can be pre- 
pared synthetically from benzol by replacing one atom of hy- 
drogen by methyl (p. 320). By the action of oxidizingagents 
it is converted into benzoic acid, thus; C7 Ha + 03 = C7 H6 
Oa + Ha O. 
Nitro-toluol, C7 H7 (NO.-), is obtained by the action of 
nitric acid upon toluol, and by reduction a basic substance is 
obtained analogous to aniline, and called amido-toluol, or 
Toluidine,, C7 H„ N or C6 H6 (NH,) (CH3). This is a solid 
substance, which exists always in commercial aniline, and in 
fact is a necessary ingredient for the purpose of the manu- 
facture of the red and violet aniline colors. Toluidine fuses 
at 40°, and boils at 198°. Toluidine is isomeric with benzyl- 
amine. 
Cressol, C7 H7 (HO), a crystallizable solid, homologous 
with phenol, contained in the crude carbolic acid ; it boils at 
203°. 
Rosaniline, C20 Hi9 Ns. The compounds of this substance 
form the splendid red-aniline color, known as magenta. The 
color may be obtained in various ways, from crude aniline ; 
the best process consists in heating this crude substance and 
arsenic acid together to a temperature of from 120° to 140°; 
the quantities taken being 12 parts of dry arsenic acid of com- 
merce (containing 13-5 per cent, of water) to 10 parts of 
aniline. The color cannot, however, be prepared at all from 
pure aniline; the presence of toluidine is necessary for its 
formation. It is a singular fact, that the pure base, rosani- 
line, is a colorless substance, and that it is only in its salts 
that its magnificent coloring powers become visible. The 
crystals exhibit by reflected light the metallic green color 
of beetles’ wings, but are of a deep red color when viewed 
by transmitted light; they are soluble in alcohol, yielding Elementary Chemistry. 
325 
splendid red solutions. By the action of nascent hydrogen 
on rosaniline, a new base is formed which forms colorless 
salts ; to this the name of Leucaniline has been given. It 
contains 2 atoms more hydrogen than rosaniline, these two 
bodies standing in the same relation as blue and white indigo 
(p. 328). 
An Aniline blue is obtained by the replacement of 3 atoms 
of hydrogen in rosaniline by phenyl, Cs H5, whilst a violet is 
obtained by substituting 3 of methyl, ethyl, or any of the al- 
cohol radicals. 
C h ) 
Benzyl Alcohol, 1 | O, obtained by the action of al- 
coholic potash, or nascent hydrogen, on oil of bitter almonds 
(which is the aldehyde of the series). It is an oily colorless 
liquid, boiling at 207°. Oxidizing agents converted first into 
the aldehyde, C7 He O, and lastly into the acid of the series, 
C7 He 02, benzoic acid. 
Benzoic Aldehyde. Oil of bitter almonds, 7 |> . This 
oil does not exist already formed in bitter almonds, but is the 
result of a decomposition of the amygdaline contained in the 
almond (p. 318). 
It can likewise be obtained by distilling a benzoate and a 
formate—in this respect resembling the aldehyde of the alco- 
hol group; it also forms a crystalline compound with sodium- 
hydric-sulphite. Bitter almond oil is a colorless strongly- 
smelling liquid, boiling at 180° ; the commercial substance 
(used in cookery) is very poisonous, as it invariably contains 
an admixture of acid. On exposure to air or 
oxygen, or when acted upon by oxidizing agents, it is con- 
verted into benzoic acid. Benzoic aldehyde may be regarded 
as toluol or methyl benzol, in which two atoms of hydrogen 
of the methyl are replaced by one atom of oxygen, C6 Hr, 
(C H O) ; whilst Benzoyl Chloride, C7 H5 O Cl, is the last sub- 
stance in which the one remaining atom of hydrogen in the 
methyl is replaced by chlorine. The vapor of bitter almond 
oil decomposes into benzol and carbonic oxide when passed 326 
Elementary Chemistry. 
through a red-hot tube ; and benzoyl chloride is formed by 
the direct action of chlor-carbonyl on benzol, the monad 
group (C O Cl) changing places with one atom of hydrogen, 
thus : 
CO Cl, + C, H6 = C6 H5 (C O Cl) + H Cl. 
Chlor-carbonyl. Benzol. Benzoyl Chloride. . 
Ben>zoyI chloride can also be formed by the action of phos- 
phorus pentachloride upon benzoic acid; it is a colorless li- 
quid, boiling at 199°. 
C H O ) 
Benzoic Acid, 7 V O. Found in many resins, espe- 
cially in gum benzoin ; it also occurs in the urine of cows, 
and in the putrefied urine of man and other animals ; it can 
be obtained by the oxidation of benzyl alcohol and bitter al- 
mond oil. Benzoic acid may be easily prepared by heating 
gum benzoin, when the acid sublimes in pearly white plates ; 
it fuses at 121° and boils at 250°, Benzoic acid forms a series 
of salts, most of which are soluble ; the ferric benzoate falls 
as an insoluble red precipitate when sodium benzoate is added 
to ferric chloride. 
C H- O ) 
Benzoic Peroxide, (y7jq°o ( O2. A well-crystallized sub- 
stance, obtained by the action of barium peroxide on benzoyl 
chloride ; it explodes when heated, and resembles acetyl per- 
oxide (p. 277). 
C H O ) 
Benzoic Benzoate, or Benzoic Anhydride, q j_j5 q - O. 
obtained by acting upon potassium benzoate with benzoyl 
chloride, thus : 
Cl Hs ° | O + C, H6 O Cl = § Hi O | O + K CL 
It is a solid substance, fusing at 240, and boiling at about 
310°; it is soluble in alcohol and ether, and several mixed 
anhydrides are also known — thus we have acetyl ben- 
. C2 Hs O I n 
zoate, He Q J O. Elementary Chemistry. 
327 
c7h7^ 
Benzylamine, H >■ N ; a colorless liquid, isomeric with 
H ) 
toluidine, boiling at 182°, obtained by the action of ammonia 
upon benzyl chloride. It is a true amine, and gives rise to 
corresponding secondary and tertiary amines. 
Hippuric Acid, C9 H9 N 03, is contained in the urine of 
horses and herbivorous animals. It can also be artificially 
prepared from zinc glycocine and benzoyl chloride; it is in 
fact glycocine, in which one atom of hydrogen is replaced by 
the radical C7 H5 O of benzoic acid, thus ; 
C2 H3 (NHa) 02. C2 Ha (C7 Hs O) (NH. 02. 
Glycocine. Glycocine-Benzoic Acid, or Hippuric Acid. 
Benzoic acid is converted by passing through the animal 
body into hippuric acid. 
Salicylic Group, This group contains the dyad radi- 
11 11 
cals, C7 H6, or C7 H4 O. Salicylic acid stands to benzoic as 
glycolic to acetic, thus; 
1. Hl0 
c2 H3 O > n Cs H2 o 1 u 
H > 1 o 
H \ 
Acetic. Glycolic. 
H 
C. H. O ) 0 C, H1.' O ( °- 
H ; ' h}°- 
Benzoic. 
And as glycolic acid is obtained from monochloracetic acid 
by the action of potash, so salicylic acid can be prepared from 
monochlor-benzoic acid. A glycol of this series called 
Saligenine also exists, from which the acid is obtained by 
oxidation. Salicylic acid is formed as a methyl compound in 
the essential oil of Gaultheria procumbens. For a descrip- 328 
Elementary Chemistry. 
tion of the remaining aromatic compounds a larger work must 
be consulted. 
Indigo. This substance is the blue coloring matter de- 
rived from several species of Indigofera, The leaves are 
macerated in water, when they undergo oxidation, forming a 
yellow substance which, on exposure to air, deposits indigo in 
the form of a dark blue powder. This, when evaporated to 
dryness and cut into small cakes, constitutes the indigo of 
commerce. The pure coloring matter termed Indigotine is 
obtained from commercial indigo in crystals by sublimation ; 
its composition is C8 Hs NO. Indigo is insoluble in water 
and in cold alcohol and ether ; strong, or fuming sulphuric 
acid, dissolves indigo, forming a deep blue solution. Indigo 
occurs sometimes in healthy urine in small quantities. When 
indigo is exposed in contact with alkalies to reducing agents 
it passes into a soluble and colorless substance by absorption 
of hydrogen. The substance thus produced is called white 
indigo; its formula is C8 H6 N O. This property is largely 
employed in indigo dyeing. An indigo-vat being prepared, 
containing i part of indigo, 2 parts of ferrous sulphate, and 3 
parts of slaked lime to about 200 parts of water, these are 
allowed to stand for some time in a closed vessel. The cloth 
is then dipped into the liquid, and on exposure to air becomes 
permanently dyed by the deposition of insoluble blue indigo 
in the fibre of the tissue. 
Isatine, C8 H6 NO2. By the careful oxidation of indigo 
this substance is formed ; it crystallizes in large deep yellow 
crystals. By the action of potash it is converted into aniline. 
C8 Hs N Oa + 4 K H O = Ci H7 N + 2 (K, C O.) + Ha. 
Isatine and Caustic Potash. Aniline. 
LESSON XL. 
Turpentines and Camphor Group. This series of 
bodies appears to contain a common group of ten carbon atoms, Elementary Chemistry. 
329 
and affording a large number of isomeric derivatives. It is 
particularly difficult to distinguish between many of these 
bodies which appear identical in their chemical relations, but 
differ in their physical properties, and hence are said to be 
physical isomers. The following are the hydrocarbons from 
which these substances are derived: 
H Cio H18 C.O His Cio H14. 
Di-amylene Camphene Terebene Cymol. 
or and its / 
Menthene. Isomers. 
These hydrocarbons yield oxidized products termed Cam- 
phors ; we thus have— 
Cio H20 O Cio His O Cio Hio O Cio Hit O. 
Menthen-camphor. Borneo-camphor. Laurel-camphor. Thymol and 
Carvol. 
The camphors stand in the same relation to the above 
hydrocarbons as benzyl alcohol stands to toluol. By a further 
process of oxidation acids are formed ; thus we have— 
C10 His terebene, Cio Hio 02, camphinic acid. 
Cio Hio O, laurel camphor, Cio Hi« 04, camphoric acid. 
Turpentines and Isomers, Cio HJ6. Oil of turpentine of 
commerce generally consists of a mixture of several isomeric 
modifications of this hydrocarbon. It is obtained from several 
species of pine ; that from Times nigra, abies, and sylvestris 
constitutes common turpentine—that from the larch is known 
as Venice turpentine. On distillation with water a volatile 
aromatic liquid comes over, and rosin or colophony remains 
in the retort. 
The best-known natural varieties are terebenthene from the 
Pinus maritina, boiling at 161°, and possessing a power of 
left-handed polarization of —420-3 ; austra-terebenthene, from 
the Pinus Australis, boiling also at 1610, but possessing a 
right-handed polarizing power of + 2i°-5. These turpen- 
tines, when heated, or when acted on by sulphuric acids and 
other re-agents, form isomers differing in their action on the 
ray of polarized light, some being right- and some left-handed, Elementary Chemistry, 
330 
whilst others are inactive. Terebenthene combines with 
hydrochloric acid, and forms isomeric compounds ; it also 
combines with water to form a solid hydrate. On oxidation, 
the turpentines pass into resins. 
Many essential oils are isomers of turpentine; of these 
may be mentioned essential oil of lemons, of bergamotte, 
neroli, lavender, pepper, camomile, carraway, cloves, &c. 
These often contain other oxidized oils in addition to the 
terebenes. Of these bodies laurel, or common camphor, 
C10H10O, is the most important; it is yielded chiefly by the 
Laurus camphora of China and Japan, although it can be 
obtained from other plants. Camphor is a white, crystalline, 
semi-transparent mass ; it fuses at 175°, and boils at 204°; 
it is soluble in alcohol, and its solution deviates the plane of 
polarization to the right + 47°'4. Camphor dissolves in 
alcoholic potash unaltered, but, on heating, is first converted 
into Borneo camphor, CioHieO,and afterwards into camphinic, 
CioHieCb, and campholic acid, CioHisOa. On boiling with 
nitric acid, it is oxidized to camphoric acid, C10 HJ6 04. Like 
the turpentines, camphor also exists in several physical isomeric 
modifications, which chiefly differ in their action on polarized 
light. The camphoric acid obtained from these different cam- 
phors also exhibit differences in their properties. 
Resins and Balsams.—Resin, or colophony, is obtained in 
the distillation of crude turpentine ; the other resins, such as 
lac, mastic, copal, &c., have a similar Composition. They 
are oxidation products of the terebenes. 
Caoutchouc, or India Rubber, and Gutta Percha. — Tht first 
of these is a compound of hydrogen and carbon, and is an 
invaluable substance to the chemist; it is the hardened juice 
of several tropical trees, and in the pure state is white. 
Caoutchouc combines with sulphur in various proportions, 
forming the vulcanised caoutchouc of commerce, which con- 
tains from 2 to 3 per cent, of sulphur. If heated more strongly 
with sulphur, a black, horny mass called ebonite or vulcanite, 
is formed. Gutta percha is also the hardened juice of a 
species of a sapotacea, growing in Borneo, Singapore, &c. Elementary Chemistry. 
The pure substance is white, and insoluble in alcohol, but 
soluble in ether. 
Naphthalin, Cio He, is a solid hydrocarbon, formed in large 
quantities in the process of the distillation of coal, and found 
in the heavy oils of coal tar. It is also formed when the 
vapors of many organic bodies, such as alcohol and acetic 
acid, are passed through a red-hot tube. Naphthalin crystal- 
lizes in pearly white plates, which dissolve in hot alcohol 
and cold ether; it fuses at 79°'2 and boils at 218°, but may 
be sublimed at a lower temperature. When heated, and a 
light applied, it burns with a luminous and smoky flame. 
Naphthalin forms with strong sulphuric acid two compound 
acids, corresponding to sulphovinic acid. Nitric acid attacks 
naphthalin, forming nitro-substitution products, and also an acid 
termed phthalic acid, CgHeCb ; this substance is connected 
with the benzol series, inasmuch as on heating with excess 
of lime, or baryta, it is converted into benzol:— 
CsHgOi = C2Cb + CoHa. 
Phlhalic Acid. Benzol. 
The nitro-substitution products of naphthalin are four in 
number, being bodies in which I, 2, 3, or 4 atoms of hydrogen 
are replaced by the group N02. From nitro-naphthalin, 
CioHt(NOj), an amido-naphthalin is formed by substitution of 
N02 by NH2; this substance, Ci0H7(NH2), is generally 
termed naphthylamine. Di- and tri-amido-naphthalin are also 
known. The chlorine substitution products of naphthalin are 
very numerous bodies, in which x, 2, 3, 4, 6, and 8 atoms of 
hydrogen in the original hydrocarbon are replaced by chlorine. 
A second series of chlorine compounds is known, which are 
substitution products of naphthalin di-chloride, Ci0H»C12. 
Nearly connected with the naphthalin group is the important 
coloring matter derived from madder, and termed alizarin, 
CioH608. This substance appears not to be contained ready- 
formed in madder, the root of Rnbia tinctoria, but to be pro- 
duced, together with glucose, from a body termed rubian by 
the action of acids, alkalies, and ferments. Alizarin is 332 
Elementary Chemistry. 
deposited in long, red, needle-shaped crystals. It is but 
very slightly soluble in cold, but more soluble in hot water, 
and easily dissolves in alcohol. Alizarin produces insoluble 
red-colored compounds with alumina and stannic oxide, which 
are termed lakes, and a purple or black compound with ferric 
oxide. Hence, in calico printing solutions of these oxides 
are used as mordants, and are printed in pattern on the cotton 
cloth which, after undergoing certain preparatory processes, 
is then boiled in the “dye-beck,” containing the ground mad- 
der-root mixed with water. The alizarin of the madder forms 
with the mordanted cloth an insoluble compound, which is 
colored pink, purple, black, or chocolate, according as the 
mordant has been pure alumina, or pure iron, or a mixture of 
the two. Animal fabrics, such as silk or wool, do not require 
the application of mordants; they are able alone to fix and 
render insoluble the coloring matter. 
A substance isomeric with alizarin has been artificially pre- 
pared from the naphthalin compounds ; it crystallizes in yellow 
needles, insoluble in water, but soluble in ether. Mordanted 
cotton cloth cannot be dyed with this compound, but silk and 
wool are colored yellow. 
Vegeto-Alkaloids. 
Under this name a series of bodies containing carbon, 
hydrogen, oxygen, and nitrogen is grouped, which act as 
bases, and are found in certain plants. These bodies, for the 
most part, have not been artificially prepared, and although it 
is believed that they belong to the class of compound ammo- 
nias, yet their constitution is at present unknown. Some few 
of the alkaloids are liquid and volatile, and contain only car- 
bon, hydrogen, and nitrogen : these have a more simple con- 
stitution. The alkaloids exert a powerful influence on the 
ray of polarized light, some deviating the plane to the right 
and some to the left; they also combine with acids to form 
Salts, in this respect resembling ammonia, thus :— Elementary Chemistry. 
333 
Type, NH, + HC1 = NH«C1 or. NH.HCl. 
C„H19NO, + HC1 = Ci»HaoNO.Cl or C1TH19N08HC1. 
Morphine. Morphine Hydrochlorate. 
They also form double crystallizable salts, with platinic 
chloride, in this respect again resembling ammonia. The 
alkaloids act most violently on the animal economy; some, 
such as strychnine, nicotine, &c., form the most violent poisons 
with which we are acquainted, whilst others, such as quinine 
and morphine, act as most valuable medicines. 
Alkaloids containing Carbon, Hydrogen, and Nitrogen. 
Piperidine, C6 Hn N. This alkaloid is obtained by dis- 
tilling piperin, C17 Hi9 NO3, the base contained in black pepper. 
Piperidine contains one atom of hydrogen, which can be 
C H ) 
replaced by an alcoholic group, hence its formula is 6 jM N. 
It is a colorless liquid, boiling at 106°, and possessing a strong 
ammoniacal odor of pepper. 
Conine] C8 Hi6 N, contained in the hemlock, Conium macu- 
latum; it is a colorless liquid, boiling at 212°, and has a 
strong alkaline reaction, forming salts with acids. Conine 
acts as a narcotic poison. Under certain circumstances, 
conine yields butyric acid, by oxidation. 
Nicotine, Cio Hu N«, is the chief alkaloid, contained in 
tobacco, which contains varying quantities, from 2 to 8 per 
cent, of this substance. Nicotine boils about 240°, under- 
going partial decomposition, but it may be distilled in an 
atmosphere of hydrogen without loss. 
Nicotine is soluble in water, alcohol, and ether, and it acts 
as one of the most violent poisons with which we are 
acquainted ; a small quantity acting on the motor nerves, 
and producing convulsions and afterwards paralysis. Nicotine 
does not contain any hydrogen replaceable by an alcohol 
radical, and when treated with iodide of ethyl, a salt corre- 
sponding to ammonium iodide is produced; 334 
Elementary Chemistry. 
Ill 
C H ) CSHT ) 
rir I nr f XT T 
{ Ns c6 h7 \ N’ T*- 
C6 H7 ) 2 (C, H.) ) 
Nicotine. Ethyl-nicotine Iodide. 
A Ikaloids containing Carbon, Hydrogen, Oxygen, and 
Nitrogen. 
Alkaloids of Opium. Opium is the dried juice of the head 
of the poppy (Papaver somniferum); it is prepared largely 
in Asia Minor, Turkey, Egypt, and India; the Smyrna 
opium is most esteemed, and contains from 10 to 15 per 
cent, of morphine. There are no less than six different 
alkaloids contained in opium ; of the semorphia and narcotine 
are found in largest quantity : 
Morphine, C77 Hm N03. Papaverine, C20 H2i N04. 
Codeine . Ci8 H24 NOs. Narcotine . C22 H23 N07. 
Thebaine. Ci9 H2i N03. Narceine . C23 H29 N09. 
In addition to these substances, opium contains a neutral 
crystallizable substance called Meconine, C10 Hi0 04, and an 
acid called Meconic Acid, with which the alkaloids are chiefly 
combined, as well as many other substances in small quan- 
tities, besides vegetable matter, &c. These alkaloids, although 
possessing a very closely analogous composition, have not 
yet been converted one into the other. Opium acts as a 
most valuable medicine, in small doses acting as a sedative, 
although heightening the pulse and the action of the heart. 
Taken in larger doses it acts as a narcotic poison, a stupor 
and prostration soon ensuing, resulting in loss of all voluntary 
power of motion, complete coma, and death. It appears that 
thebaine is the most powerful of the alkaloids, then papaverine, 
narcotine, codeine, and morphine. 
Morphine, C47 H49 N03 + H20. In order to prepare 
morphia, the opium is extracted with water, and the meconic 
acid precipitated by calcium chloride ; on evaporating the fil- 
trate, crystals of morphine-hydrochlorate separate out. Mor- 
phine dissolves in 1,000 parts of cold and 400 of boiling Elementary Chemistry. 
335 
water ; hot alcohol dissolves it easily, whilst it is insoluble 
in ether. It forms crystalline salts soluble in water, and it 
appears to contain no replaceable hydrogen ; as an ammo- 
nium-iodide is obtained when it is acted upon with ethyl 
iodide. Small quantities of morphine can easily be detected 
by the formation of a deep blue coloration, when this sub- 
stance comes in contact with ferric chloride. 
Codeine, C18 H2i N03 4- H20, is left in the mother liquors 
from which the morphine has crystallized. Codeine is much 
more soluble in water than morphine, and is contained in 
opium in much smaller quantities ; it has a strong alkaline 
reaction and neutralizes acids. 
Thebaine, Ci9H2i N03, is contained in very small quanti- 
ties in opium ; its poisonous properties are more violent than 
any other of these alkaloids ; it produces tetanus. 
Papaverine, C20 H2l N04. Distinguished from the other 
opium bases by giving a deep blue color with strong sulphu- 
ric acid. 
Narcotitie, C22 H23 N07, remains insoluble when opium is 
treated with water, and it is obtained by dissolving it out 
from the “ marc ” or insoluble portion of the opium with 
hydrochloric acid. It dissolves in 128 parts of boiling alco- 
hol and 19 of boiling ether. Narcotine when heated with 
potash furnishes ammonia and methylamine, as well di- and 
tri-methylamine ; and when treated with hydriodic acid, it 
furnishes 3 molecules of methyl iodide for every molecule of 
narcotine. 
Alkaloids of the Sirychnos. Two alkaloids possessing 
most powerful poisonous properties, and called Strychnine 
and Brucine, are found in the seeds of the Strychios nux 
vomica, and in the Strychnos Ignatius or the St. Ignatius’s, 
bean. Strychnine, C21 H22 N202, is a base forming crystal- 
lizable salts, of which per cent, is contained in the St. 
Ignatius’s bean. It acts as a violent poison, producing 
tetanic convulsions ; it however is sometimes given in very 
small doses in medicine ; its salts are all extremely bitter and 
tart. Strychnine can be detected when present in minute 336 
Elementary Chemistry. 
quantities, by yielding, with sulphuric acid and potassium 
bichromate, an intense purple color, which passes rapidly into 
a red, and then into a yellow color. 
Brucine, C23 H2fl N2 04 + 4 H20, is found alone in false 
angustura bark, and together with strychnine in mix vomica ; 
it is more soluble in water and alcohol than strychnine. 
Brucine and its salts are less poisonous and less bitter than 
the strychnine compounds ; it can be distinguished from 
strychnine by the bright red color produced when this sub- 
stance is moistened with nitric acid ; indeed this reaction may 
also be employed as a most delicate test for the presence of 
nitric acid. 
Alkaloids of the Chinchofias. The bark of this species of 
trees, originally grown in Peru, but now transplanted to Java 
and India, contains 2 alkaloids, quinine and cinchonine, and 
each of these yields 2 isomeric modifications, quinidine and 
quinicine ; cinchonidine and cinchonicine. 
The Alkaloids are combined in the bark with a peculiar 
acid termed quinic acid. Quinine is a most valuable medi- 
cine, acting as a febrifuge ; cinchonine does not possess the 
same valuable properties. 
Quinine, C20 H24 N202. This alkaloid maybe precipitated 
from the solution of its sulphate as a white crystalline powder. 
It dissolves in 350 parts of cold water, and in 2 parts of alco- 
hol. Its solution has a strong bitter taste, and deviates the 
plane of polarization to the left. Quinine may be detected 
by adding chlorine-water, and afterwards an excess of ammo- 
nia, to solutions of the sulphate, when a green color is pro- 
duced ; another characteristic reaction consists in the deep 
red color produced when finely powdered potassium ferro- 
cyanide is thrown into the solution of quinine in chlorine 
water. Quinine appears .to possess no replaceable hydrogen, 
as when treated with ethyl iodide a salt of an ammonium com- 
pound is formed. Quinine sulphate is the salt used in medi- 
cine ; it is not very soluble in water, but dissolves easily 
when a drop or two of sulphuric acid is added. Its solution 
possesses very strongly the property of fluoresceiice. Elementary Chemistry. 
337 
Quinidine and Quinicine. The first of these isomers of 
quinine is found in the bark, and it resembles quinine in its 
febrifuge qualities, but it deviates the plane of polarization 
strongly to the right. Quinicine is obtained by acting upon 
quinine by heat. It is a bitter substance, possessing a semi- 
solid resinous consistency, and deviating the plane of polari- 
zation feebly to the right. 
Cinchonine, C20 H24 Na O. This body is separated from 
the quinine, which accompanies it, by its less solubility in 
alcohol; thus cinchonine requires 30 parts of boiling alco- 
hol for solution, and therefore crystallizes out whilst the 
quinine remains in solution. Cinchonine is not nearly so 
powerful a febrifuge as quinine ; it is, however, used as a 
medicine in some countries. Although it only differs from 
quinine by containing one atom less oxygen, it has not yet 
been transformed into the latter. It does not produce a green 
color with chlorine-water and ammonia like quinine ; it acts 
as a strong base, and forms salts which are more soluble in 
water and alcohol than those of quinine. 
Cinchonidine—Cinchonicine. The first of these isomers is 
found, together with quinidine, in the brown resinous mass 
left after the extraction of the two chief alkaloids. It pro- 
duces a left-handed rotation on a polarized ray, whilst cin- 
chonine produces a right-handed polarization. Cinchonicine 
is obtained by heating a cinchonine sulphate to 120° or 130° ; 
it deviates the polarized ray feebly to the right: hence we have 
Quinine exerting a powerful left-handed rotation, 
Quinidine “ powerful right-handed “ 
Quinicine “ feeble right-handed “ 
Cinchonine “ powerful right-handed “ 
Cinchonidine “ powerful left-handed “ 
Cinchonicine “ feeble right-handed “ 
Theobromine, C7 H8 N4 02, the crystallizable alkaloid con- 
tained in cocoa (Theobroma Cacao). If in this substance one 
atom of hydrogen be replaced by methyl, Cafeine is formed. 
Cafeine, or Theine, C8 H10 N,4 02 + H .O. The active 338 
Elementary Chemistry. 
principle of tea and coffee ; also found in the leaves of Ilex 
Paraguayensis, which the South Americans much use in 
place of tea ; also in guarana, a kind of chocolate made from 
the fruit of Paulinia Sorbilis. The quantity of the alkaloid 
contained in tea is about 2 per cent.; in coffee, o-8 to I per 
cent. ; in guarana 5 per cent.; and in the Paraguay tea 
about 1-2 per cent. 
A description of the numerous alkaloids of less general 
interest will be found in the larger manuals. 
LESSON XLI. 
Albuminous Substances. 
Under this head we class a number of peculiar compounds 
forming a characteristic and essential portion of the bodies 
of animals, and occurring also in certain parts, especially the 
seeds, of vegetables. These compounds possess a very com- 
plicated constitution, and our knowledge of their true chemi- 
cal relations is most incomplete. They do not crystallize, 
and exist in an amorphous jelly-like form ; hence if is very 
difficult to obtain them in the pure state, so that there is some 
doubt even about their chemical composition. They all con- 
tain sulphur, and most of them phosphorus, in addition to 
carbon, hydrogen, oxygen, and nitrogen, and in their different 
forms possess nearly the same composition. 
Albumin is seen in one of its purest forms in the white of 
egg ; it is also contained in the serous or liquid portion of the 
blood. It may be obtained by adding acetic acid to white of 
egg and diluting with water, when a white flocculent precipi- 
tate of albumin is formed. When dried, it forms a yellow, 
transparent, gum-like mass ; this, on addition of cold water, 
remains as a white insoluble powder, which, like the precipi- 
tated albumin, dissolves in water containing a small trace of 
free alkali. One of the most characteristic properties of 
albumin is its power of coagulation ; if soluble white of egg Elementary Chemistry. 
339 
be heated to about 65° C, it becomes solid and opaque; in 
this state it is insoluble in water, but dissolves in dilute alkali. 
Fibrin. This substance exists in solution in the blood, but 
immediately becomes solid when the blood leaves the living 
body ; it can be obtained by washing the clot, or thick part of 
blood, until the red color has disappeared, or it may be 
obtained by agitating fresh blood with twigs. It then is 
obtained in the form of colorless filaments, which are tasteless 
and insoluble in water ; on drying, it forms a horny mass 
like albumin. The fibrin of flesh appears to differ from that 
of blood ; and differences have been observed between the 
fibrin from arterial and that from venous blood. 
Casein is the nitrogenous substance contained in milk and 
cheese ; it closely resembles albumin in its properties, being 
coagulated by acids. Casein is insoluble in pure water, but 
dissolves in a very dilute solution of an alkali. In milk the 
casein is not coagulated by boiling, but an acid, or a portion 
of the inner coating of the calf’s stomach, called rennet, at 
opce separates out the casein and butter as curds, and leaves 
the milk-sugar, and salts in solution as whey. 
Vegetables contain similar substances, which are scarcely 
to be distinguished from the bodies derived from an animal 
source. Glutin, or the sticky, elastic substance contained 
with starch in wheaten flour, is vegetable fibrin, whilst vege- 
table albumin and casein occur in the juices and seeds of 
plants. The following table shows the percentage composi- 
tion of the albuminous bodies ; it is impossible to give any 
formulae for these complicated substances : 
Albumin. Fibrin. Casein. 
Carbon . . . 53-5 527 53-8 
Hydrogen . . To 6‘q 7-2 
Nitrogen. . . I5'5 I5'4 15*6 
Oxygen . , . 22-o 225 
Sulphur ... 1 '6 1-2 o-9 
Phosphorus. . o-4 03 0 0 
lOO'O 1000 lOO'O Elementary Chemistry. 
340 
Gelati7i is a nitrogenous substance obtained from the animal 
body ; it is prepared by boiling the tissues, and is then known 
as glue, isinglass, or gelatin; its composition is the same as 
that of the tissue from which it is prepared. 
Animal Chetnislry is a most important branch of chemical 
science, and one which unfortunately is but very slightly 
advanced : our knowledge of the composition and chemical 
constitution of the substances contained in the animal body is 
very incomplete, and concerning many of the chemical changes 
which occur in the different parts of the animal we are almost 
entirely ignorant. 
The Bones of animals consist principally of tribasic calcium 
phosphate, together with a kind of gelatin ; the earthy phos- 
phate dissolves in hydrochloric acid, leaving the bone as an 
elastic gelatinous mass ; when burnt, the friable and earthy 
matter alone remains. Bone contains— 
Animal matter 33 
Calcium phosphate 57 
Calcium carbonate 8 
Calcium fluoride 1 
Magnesium phosphate .... 1 
100 
The Blood of animals is the channel by means of which 
their bodies not only receive all the requisite supply of ma- 
terials for their growth and for the repair of waste, but by 
means of which they are able to get rid of the worn-out 
matters which need immediate removal. In vertebrate ani- 
mals the blood has a red color and a temperature above the 
medium in which the animal lives ; in mammalia, and espe- 
cially in birds, this artificial warmth is plainly noticed. The 
temperature of the blood is singularly constant in different 
animals under the most varying conditions of climate ; it is 
36° 9 (98° F.) in man and 420,8 (or 109° F.) in birds. The 
chief peculiarity of blood is the existence in it of very small 
round or oblong discs, differing in size and shape in different Elementary Chemistry. 
341 
animals (diameter 0-0075 mm- 'n man, and four times as large 
in frogs). These are called the blood-globules, or corpuscles ; 
they are of a red color, and float in a colorless liquid; when 
the fibrin coagulates it carries down with it mechanically the 
red globules. 
Healthy human blood possesses the following average com- 
position, and its specific gravity is 1-055 : 
Coagulum, j Fibrine 0-30) 
or clot. ( Corpuscles 12-70 | °* 
{Water 79-00) 
Albumin 7-oo 0 
Fatty matters . , . . 0-06 | °* 
Salts 0-94 J 
The color of the blood discs is due to a substance called 
hcematin; this contains about 7 per cent, of iron, but the iron 
can be withdrawn by sulphuric acid without any apparent al- 
teration of the red coloring matter. Blood is charged with 
dissolved gases, especially oxygen, nitrogen, and carbonic 
acid ; and the oxidation of the tissues is effected by the pres- 
ence of the former gas : the arterial blood (freshly oxidized 
from the lungs) contains in 100 volumes 14-5 volumes of nitro- 
gen, 62-3 of carbonic acid, and 23-2 of oxygen ; whilst in 
venous blood (charged with the products of combustion of 
the body) the same gases are found in the proportion of 
13*1, 71 *6, and 15-3 volumes respectively. 
Amongst the other most important animal fluids may be 
mentioned Gastric Jtiice, a clear liquid secreted by the lining 
membrane of the stomach and the active agent in effecting 
the digestion and solution of the albuminous parts of the food. 
It has an acid reaction due to the presence of free lactic and 
hydrochloric acids. The Bile, a liquid secreted in the liver 
and poured out into the duodenum ; this substance contains 
several peculiar nitrogenized acids, viz., taurocholic acid 
C26 H4s N SO7, and glycocholic acid, C28 H43 N 08. A pe- 
culiar substance termed taurin, C2 H7 N S03, is obtained by 
the action of acids on bile; this body, which is isomeric with Elementary Chemistry. 
342 
the compound of aldehyde ammonia with sulphurous acid, 
can be prepared artificially by heating ammonium-isethion- 
ate, H4 NCsHsS 04, which parts with H2 O, and forms 
taurin. 
Milk. The composition of this important secretion varies 
considerably in different animals, but each kind contains all 
the materials needed for the formation of the body of the 
young animal; thus it contains casein (a body having nearly 
the same composition as flesh), fats (butter), and milk sugar, 
together with those inorganic salts, especially the alkaline 
chlorides, and calcium phosphates, needed for the formation 
of bone. The following gives the average composition of 
milk of different animals :— 
Woman. Cow. Goat. Ass. Bitch. 
Water 88'6 Sa'o go's 66-3 
Butter a-6 4-o 4-S i-4 i4'8 
Milk Sugar and Soluble Salts... 4'o 5-o 4-S 6 4 a'g 
Casein and Insoluble Salts 3'9 3-6 g'o i‘j i6'o 
The specific gravity of milk varies from 1-03 to i'04. 
The Uritte. It is in the urine that a large portion of the 
waste nitrogenous portions of the body pass off as urea and 
uric acid ; the urine is secreted by the kidneys from the 
arterial blood. Healthy urine contains, in 1,000 parts, 957 
parts of water, 14 of urea, 1 of uric acid, 15 of other organic 
matter, and 13 of inorganic salts. 
Functions of Animals and Plants. 
The general characteristics of animal and vegetable life 
may be stated as follows : the animal lives upon organized 
materials, taking up oxygen and evolving carbonic acid and 
other oxidized products ; the plant lives upon unorganized 
materials, especially carbonic acid, water, ammonia, and salts, 
organizing them and evolving oxygen. The chemical func- 
tion of the animal is oxidation, that of the plant reduction. 
The food of the plant serves merely to increase its bulk ; 
that of the animal is employed (after it has attained its full Elementary Chemistry. 
343 
growth) to replace the material worn out by all the active 
operations of life. The animal obtains the energy necessary 
for its existence from the oxidation of its own body ; the 
plant obtains the energy necessary for the organization of its 
food directly from the sun. 
Respiratioti and Animal Heat. The process of respira- 
tion, essential to the life of all animals, consists in the aera- 
ting of the blood circulating through the lungs or similar appa- 
ratus, by means of the oxygen of the air. The blood does 
not come into actual contact with the air, but is separated by 
a large surface of very thin membrane, through which the 
exchange of gases tak.es place by solution and diffusion. 
Not only does the blood gain in oxygen (see Blood, p. 340), 
but it loses the products of combustion with which it is 
charged, and is thus rendered fit again to circulate and carry 
away used-up material. The volume of air thrown out of the 
human lungs at each ordinary expiration amounts to from 350 
to 700 cubic centimeters : this, however, by no means empties 
the lungs, whose capacity is much greater ; the number of 
respirations amounts to about fifteen in each minute. The 
expired air differs remarkably from the inspired air, as it con- 
tains from 3 to 6 per cent, of carbonic acid, and will not sup- 
port the combustion of a candle. 
Under different circumstances of health or disease, activity 
or repose, sleeping or waking, after a meal or fasting; ac- 
cording to the temperature, pressure of the air, and from 
other varying conditions, the quantity of exhaled carbonic 
acid varies considerably. The determination of the quantity 
of carbonic acid exhaled by an animal under the above cir- 
cumstances is a subject of the highest importance, but one 
which is surrounded by numerous experimental difficulties. 
We may assume, as the result of the best experiments, that a 
man gives off 198 litres of carbonic acid (at 0° and 760 mm.) 
each hour ; this amounts to about 40 grms. of carbonic acid, 
or 11 grm. of carbon per hour : the heat which is always 
evolved by the combustion of this carbon goes to keep up 
the temperature of the body. It is difficult to determine with Elementary Chemistry. 
344 
accuracy how far the whole of the animal heat can be ac- 
counted for by the combustion of this carbon, as the chemical 
changes which go on in the body are of a very complicated 
nature, and as yet little understood. Considering, however, 
the subject in a general point of view, there cannot be much 
doubt that the whole of the animal heat is derived from the 
combustion of the materials of the body ; thus we find that in 
birds, whose temperature is higher than that of mammalia, 
the quantity of carbonic acid evolved is more than half as 
much again as in larger animals ; whilst in cold climates, 
where the loss of animal heat is great, men find it necessary 
to eat enormous quantities of fat, this doubtless serving to 
maintain the temperature of the body. 
The effect of starvation on the quantities of carbonic acid 
and urea, taken as representing the rate of change going on 
in the body, is very remarkable; in a dog, the quantity of 
carbonic acid was reduced by fasting for ten days to one-third, 
and the urea to one twenty-second part of the amount given 
off on full diet; whereas in a man the carbonic acid was 
nearly reduced to one-third by starvation. An interesting 
fact has been observed, viz., that hydrogen and marsh-gas 
are evolved in small quantities from the skin and lungs under 
certain conditions. This subject is quite in its infancy, and 
demands careful experimental investigation, as it is by such 
patient research alone that we can hope to form any real 
estimate of the income and expenditure of the body. The 
special Study of the chemistry of the body has been 
made a separate branch science, termed Physiological 
Chemistry. 
Food of Plants. Animals, as we have seen, are unable to 
produce the complicated chemical compounds which they 
need for their structure ; plants are, however, able to do this, 
and from the elementary constituents to build up their various 
parts. This function of plants is entirely dependent upon the 
sunlight; without sunlight the green coloring matter of the 
leaves of plants cannot decompose the atmospheric carbonic 
acid, and, therefore, without sunlight, the plant cannot grow. Elementary Chemistry. 
In order to separate the atoms of carbon and oxygen, an 
expenditure of force is necessary; this force is derived from 
the rapidly vibrating solar rays ; it is they which tear asunder 
the carbon and oxygen atoms, and thus enable the leaves to 
take up and assimilate the carbon, throwing out the oxygen 
into the air for the subsequent use of animals. When vege- 
table matter is ignited, it burns to carbonic acid, and generates 
exactly the same amount of force, as the vibrations of heat, 
which were needed, in the form of vibrations of light, originally 
to decompose the atmospheric carbonic acid. Hence when 
coal burns, the light and heat evolved may truly be said to be 
that of the sun; and, as animals depend for their existence 
upon vegetables, and these in their turn cannot live without 
the solar radiations, animals may with truth be called children 
of the sun. 
The bodies of plants may be considered to be composed of 
two kinds of substances, organic, such as starch, vegetable 
fibre, &c.; and inorganic salts, constituting the ash of the 
plant. The carbon, needed for the first of these materials, 
the plant obtains mainly from the atmosphere ; the nitrogen, 
hydrogen, and oxygen, which the organic substances contain, 
the plant takes up both by its leaves and by its roots ; whilst 
the whole of the inorganic salts are absorbed from the earth 
by the roots, which act as the mouth of the plant, whilst the 
leaves may be compared to the lungs of animals. Every plant 
has in the atmosphere an unlimited supply of carbon and 
water ; but for the supply of inorganic materials, the plant is 
dependent upon the nature of the particular soil upon which 
it grows. Plants possess the peculiar power of selection, by 
the roots, of the mineral constituents of food, as well as the 
subsequent chemical elaboration of the materials. Of the 
causes of the changes which thus go on we know nothing: 
thus we cannot explain why an acorn turns out always to be 
an oak, or why of two seeds sown in the same soil and exposed 
to the same sunlight and air, one evolves a poisonous and the 
other a wholesome plant. 
Concerning the growth of plants a large amount of infer- 
345 34^ 
Elementary Chemistry. 
mation has been amassed, but we are far from possessing 
even an approach to a knowledge of the laws which regulate 
this important subject. For an account of the interesting 
facts which have been ascertained respecting the questions of 
manuring, fertility of the soil, &c., we must refer the reader 
to books on the branch science of Agricultural Chemistry. Elementary Chemistry. 
347 
By Act of Parliament (27 and 28 Viet. cap. 117, 29th July, 1864) the use of the Metrical System of Weights and Measures is 
rendered legal. The weight of the Kilogramme is settled by this Act to be equal to 154323487 English grains. 
COMPARISON OF THE METRICAL WITH THE COMMON MEASURES. By Dr. Warren De La Rue. 
MEASURES OF LENGTH. 
In English 
Inches. 
In English Feet 
= 12 Inches. 
In English 
Yards 
= 3 Feet. 
In English 
Fathoms 
= 6 Feet. 
In English 
Miles 
= 1,760 Yards. 
°'°3937 
o'3937i 
3'937°8 
39’37°79 
393'7°79° 
3937'°7900 
3937°’79°°° 
393707-90000 
0-0032809 
0-0328090 
0-3280899 
3-2808992 
32-8089920 
328-0899200 
3280-8992000 
32808-9920000 
0'0010936 
0*0109363 
0- 
1- 
10-9363310 
109-3633100 
1093-6331000 
io936-33ioooo 
0 0005468 
0-0054682 
0-0546816 
0-5468165 
5-4681655 
546816550 
546-8165500 
5468-1655000 
o"oooooo6 
00000062 
0-0000621 
0-0006214 
0-0062138 
0-0621382 
0-6213824 
6-2138244 
i Inch = 2-539954 Centimetres. i Yard = 0-91438348 Metre. 
1 Foot = 3 0479449 Decimetres. 1 Mile = 1-6093149 Kilometre. 
MEASURES OF SURFACE. 
In English 
Square Feet. 
In English 
Sq. Yards = 9 
Square Feet. 
In English 
Poles — 272-25 
Sq. Feet. 
In English 
Roods = 10,890 
Sq. Feet. 
In English 
Acres = 43,560 
Sq. Feet. 
10-7642993 
1076-4299342 
107642-9934183 
1-1960333 
119-6033260 
11960-3326020 
0-0395383 
3-9S38290 
395-3828959 
0-000988457 
0-098845724 
9884572398 
0*0002471143 
0'0247II43IO 
2’4711430996 
1 Square Inch = 6-4513669 Square Centimetres. 1 Square Yard = 0-83609715 Square Metre or Centaire. 
1 Square Foot = 9-2899683 Square Decimetres. 1 Acre == 0-404671021 Hectare. 348 
Elementary Chemistry. 
MEASURES OF CAPACITY. 
In Cubic 
Inches. 
In Cubic Feet 
= 1,728 Cubic 
Inches. 
In Pints 
= 34*65923 
Cubic Inches. 
In Gallons 
= 8 Pints 
= 277-27384 
Cubic Inches. 
In Bushels 
= 8 Gallons 
= 2218-19075 
Cubic Inches. 
Millilitre, or cubic centimetre 
Centilitre, or 10 cubic centimetres 
Decilitre, or 100 cubic centimetres 
Litre, or cubic decimetre 
Decalitre, or centistere 
Hectolitre, or decistere 
Kilolitre, or stere, or cubic metre 
Myriolitre, or decastere 
0-061027 
0-610271 
6-102705 
61-027052 
610-270515 
6102-705152 
61027-051519 
610270-515194 
0-0000353 
0-0003532 
0-0035317 
o"o3S3i66 
o*353i6s8 
3*S3i658i 
35*3165807 
353-1658074 
0-001761 
0-017608 
0- 
1- 
17-607734 
176*077341 
1760-773414 
17607-734140 
0*00022010 
0*00220097 
0*02200967 
0*22009668 
2*20096677 
22*00966767 
220*09667675 
2200 9667675O 
0-000027512 
0-000275121 
0-002751208 
0-027512085 
0-275120846 
2-751208459 
27-512084594 
275-120845937 
i Cubic Inch = 16-3861759 Cubic Centimetres. 1 Cubic Foot = 28-3153119 Cubic Decimetres. 
1 Gallon = 4-543457969 Litres. 
MEASURES OF WEIGHT. 
In English 
Grains. 
In Troy Ounces 
= 480 Grains. 
In Avoirdupois 
Lbs. = 7,000 
Grains. 
In Cwts. 
= 112 Lbs. 
= 734 °°o 
Grains. 
Tons 
= 20 Cwt. 
= 13,620,000 
Grains. 
Milligramme 
Centigramme 
Decigramme 
Gramme 1 
Decagramme 
Hectogramme 
Kilogramme 
Myriogramme 
0-015432 
0-154323 
1 ‘54323 S 
i5'432349 
iS4‘323488 
iS43‘23488o 
15432-348800 
154323*488000 
0*000032 
0*000322 
0'0032I5 
0*032I5I 
0-32I507 
3*2I5073 
32*I50727 
321*507267 
0*0000022 
0*0000220 
0*0002205 
0*0022046 
0*0220462 
0’220462I 
2*2046213 
22*0462126 
0*00000002 
0*00000020 
0*00000197 
O OOOOI968 
0*00019684 
0*00196841 
0*01968412 
0*19684118 
0*000000001 
0*000000010 
0 000000098 
0*000000984 
0*000009842 
0*000098421 
0*000984206 
0*009842059 
i Grain = 0*064798950 Gramme. 1 lb. Avd. — 0 45359 Kilogr. 
1 Troy oz. = 31*103496 Gramme. 1 Gwt. — K.ilogr. Elementary Chemistry. 
349 
QUESTIONS AND EXERCISES UPON THE FORE- 
GOING LESSONS. 
In order to enable the pupil to master the principles of the 
science, he must conscientiously write out answers to the 
Questions, and work out the Exercises given in illustration 
of each Lesson. 
Lesson 1. Introduction. 
1. Describe an experiment to prove that when a candle 
burns, the materials are not annihilated. 
2. Distinguish between a chemical element and a com- 
pound. 
3. What is the construction and use of a chemical balance ? 
4. Name a few important elements. 
5. Is it likely that we are now acquainted with all the 
elements existing on the earth, and why? 
6. Describe some cases in which chemical actions occur. 
1. How did Priestley first prepare oxygen gas ? 
2. Describe the process now adopted for obtaining this gas, 
3. Whence is the name oxygen derived ? 
4. State the action produced (1) by animals, (2) by plants, 
on the air. 
5. Learn by heart the composition by weight of potassium 
chlorate. 
6. I want 100 pounds of oxygen ; how many pounds of 
potassium chlorate must I take ? 
7. What is meant by the combining weights of the ele- 
ments ? Give an example. 
8. How can hydrogen be obtained from water ? 
Lesson 11. Oxygen and Hydrogen. 350 
Elementary Chemistry. 
9- Mention the chief properties of hydrogen. 
10. What is formed when hydrogen burns in the air ? How 
can this be exhibited ? 
ir. 65-2 parts by weight of zinc in decomposing water 
yield 2 parts by weight of hydrogen. How much zinc must 
be employed to obtain 100 pounds of hydrogen ? 
12. What is the derivation of the word hydrogen ? 
[It will generally be found necessary to divide this into 
several lessons, and to familiarize the pupil to the subject by 
a much larger number of exercises than those here given.] 
1. Describe shortly the metrical system of weights and 
measures. 
2. How many cubic centimetres are contained in 1 cubic 
metre ? 
3. How is a thermometer made and graduated ? 
4. Describe the three thermometric scales now in use. 
Work out the following: 
How many degrees C. and R. correspond to + 420 and — 320 Fah. ? 
“ C. and F. “ + 327° and — 20 R. ? 
“ F. and R. “ + 78° and — 1720 C. ? 
5. If 273 volumes of gas be at the temperature of o° C., to 
what temperature must they be heated in order to expand to 
295 volumes ? 
6. What volume will 1,063 litres of hydrogen at -2° occupy 
when heated to roo° ? 
7. State Boyle’s Law of Pressures. 
8. What volume will 1,000 cbc. of oxygen at 0° and 760 
mm. become at a temperature of i6°*5, and under a pressure 
of 735 mm. ? 
9. Learn by heart the weight in grammes of one litre of 
hydrogen at 0° and under 760 mm. pressure. 
10. What simple method is used for calculating the weight 
Lesson HI. Chemical Calculations, &*c. Elementary Chemistry. 
351 
of one litre of the elementary gases at the standard tempera- 
ture and pressure ? 
11. How many cubic centimetres of oxygen gas measured 
at io° and under 745 mm. pressure can be got by heating 20 
grammes of potassium chlorate ? 
12. What is the weight in grammes of 516 litres of hydro- 
gen gas measured at — 20° and under 770 mm. pressure ? 
Lesson IV. Water. 
[It may be necessary to divide this into two or more les- 
sons.] 
1. How did Cavendish determine the composition of water ? 
2. Describe the most exact methods of determining the 
composition of water (i) by volume, (2) by weight. 
3. What is meant by the latent heat of water ? How is 
this determined ? 
4. How can you show that when a liquid solidifies, heat is 
given out ? 
5. Describe the changes in bulk which water undergoes 
when heated from o° to ioo°. 
6. When does water boil ? 
7. How is the latent heat of steam determined ? 
8. Define the term “ thermal unit.” 
9. How is the tension of aqueous vapor measured ? 
10. Why must the barometric pressure be noticed when 
graduating a thermometer ? 
11. How is pure water obtained ? 
12. What is the composition of hydric peroxide ? 
Lesson V. The Atmosphere. 
1, How may pure nitrogen gas be prepared ? 
2. What is the mean height of the barometer at the sea’s 
level ? 352 
Elementary Chemistry. 
3. Why does water boil at a lower temperature than too9 
on a mountain top ? 
4. What reasons have we for believing that the air is a me- 
chanical mixture, and not a chemical combination of nitrogen 
and oxygen ? 
5. Describe the mode of making a eudiometric analysis of 
the air. 
6. How may we determine the composition of the air by 
weight as regards nitrogen and oxygen ? 
7. Draw and describe an apparatus for estimating the quan- 
tity of carbonic gas contained in the air. 
8. What important part does this carbonic acid play as re- 
gards vegetation ? 
9. How is rain formed ? 
10. Explain the formation of dew and hoar frost. 
11. What is the use of hygrometers ? 
12. Name other constituents of the atmosphere. 
Lesson VI. Nitric Acid and Oxides of Nitrogen. 
1. Give the composition by weight of the five oxides of ni- 
trogen. 
2. Explain what is meant by chemical combination in mul- 
tiple proportions. 
3. State the principles of Dalton’s atomic theory. 
4. What happens when electric sparks are passed through 
the air ? 
5. Learn by heart the combining weights of oxygen, hydro- 
gen, nitrogen, chlorine, potassium, sulphur ; and the formulae 
of nitric acid, sulphuric acid, nitre, and potassium sulphate. 
6. Write out in symbols the decomposition occurring in the 
preparation of nitric acid, and explain the meaning of these 
symbols. 
7. I want 500 grms. pure nitric acid ; how many grms. of 
nitre and sulphuric acid shall I need, and how many grms. ot 
hydric potassium sulphate will remain ? Elementary Chemistry. 
353 
8. Mention the tests for nitric acid. 
9. How is nitric pentoxide prepared ? 
10. 100 parts by weight of this substance contain 
parts of nitrogen, and 74‘oy parts of oxygen. Show that the 
formula of the substance is Na 06. 
Lesson VII. Oxides of Nitrogen and Ammonia. 
1. Name the chief properties of laughing gas, 
2. How many grms. of nitrous oxide and water can be 
obtained from 213 grms. ammonium nitrate ? 
3. How is the composition by volume of nitrous oxide 
determined ? 
4. I want 100 litres of nitric oxide gas when the tempera- 
ture is o° and the pressure 760 mm. What weight in grms. 
of copper and nitric acid must I take ? 
5. Point out the relation between nitric pentoxide and the 
nitrates, and nitric trioxide and the nitrites. 
6. Give the formulae representing three different modes by 
which ammonia can be produced. 
7. How many litres of ammonia measured at io° and under 
a pressure of 755 mm. can be obtained from 100 grms. of sal 
ammoniac. 
8. Describe the principles of Carry’s freezing machine. 
9. How is the composition by volume of ammonia ascer- 
tained ? 
10. How can ammonia be liquefied ? 
Lesson VIII. Carbon and Carbonic Acid. 
1. Name the three allotropic modifications of carbon. 
State their chief peculiarities, 
2. Give a short description of the nature of coal. What 
changes have occurred in the passage of wood into coal ? 
3. Required 562 grms. carbonic dioxide ; how will you 
obtain it, and what weight of materials will you need to use ? Elementary Chemistry. 
354 
4. What law regulates the absorption of this gas in water ? 
5. How can carbonic dioxide be obtained in the liquid and 
in the solid state ? What peculiar property does this liquid 
exhibit ? 
6. Explain the mode adopted for obtaining very low tem- 
peratures by means of solid carbonic acid. 
7. Describe, with a drawing, the apparatus used to deter- 
mine the composition of carbonic acid. 
8. State the results of this determination. 
9. How many litres of carbonic dioxide measured at 300°, 
and under a pressure of 740 mm; can be obtained by burning 
one kilogramme of Wigan cannel (No. 5 on page 69) ? 
10. Show, by describing an experiment, that carbonic 
dioxide contains its own volume of oxygen. 
Lesson IX, Carbonic Oxide and Hydrocarbons. 
1. How many grms. of carbon will be needed to convert 
100 litres of carbonic dioxide at o° and 760 mm. into carbonic 
oxide, and how many litres of this latter gas will be formed ? 
2. Find the volume in litres at io° and 740 mm. of carbonic 
oxide which can be obtained from 100 grms. of oxalic acid 
and formic acid respectively. 
3. What is formed when caustic potash and carbonic oxide 
are heated together ? 
4. How is the composition of carbonic oxide ascertained by 
eudiometric analysis ? 
5. What is the composition of marsh-gas and fire-damp ? 
6. How is olefiant gas prepared ? 
7. State shortly the properties and composition of coal gas. 
8. How is the illuminating power of coal gas ascertained ? 
9. Describe the construction of a Bunsen’s burner. 
10. Explain the principles of the Davy lamp. 
11. How many litres of carbonic acid are formed by the 
combustion of one litre of olefiant gas ? 
12. How is cyanogen gas prepared ? Elementary Chemistry. 
355 
13. I want 50 grms. pure hydrocyanic acid ; how many 
grms. of potassium cyanide and sulphuric acid shall I need to 
use ? 
Lesson X. Chlorine. 
1. Write down as an equation the decompositions which 
occur in the preparation of chlorine from rock salt. 
2. I want 100 litres of chlorine gas at io°, and under the 
pressure of 735 mm. ; how many grms. of the materials, viz., 
Na Cl, H2 S04, and Mn 02 shall I require ? 
3. Describe experiments proving the power of chlorine to 
combine with hydrogen. 
4. Explain the bleaching action of chlorine. 
5. How many kilos, of salt and sulphuric acid must be taken 
to yield 100 kilos, of aqueous hydrochloric acid containing 
20'22 per cent, of the gas ? 
6. How is the composition of hydrochloric acid determined ? 
7. Write out the formulae of the oxides of chlorine and the 
corresponding acids, 
8. Describe the action of water upon hypochlorous oxide, 
nitric pentoxide, and carbonic dioxide. 
9. What is the composition of bleaching-powder ? 
10. How is potassium chlorate prepared ? 
11. Show from the composition of the salt that the formula 
of potassium chlorate is K Cl 03. 
12. Show that the aqueous perchloric acid containing 723 
per cent, of H Cl O4 does not correspond to any definite com- 
pound of this acid with water. 
Lesson XL Bromine, Iodine, and Fluorine. 
r. Describe the mode of obtaining pure bromine. 
2. What is the composition of bromic and perbromic acids ? 
3. Write out in an equation the decompositions occurring in 
the manufacture of iodine from potassium iodide. 356 
Elementary Chemistry. 
4. How is hydriodic acid gas prepared ? 
5. Show that the aqueous hydriodic acid, boiling at a con- 
stant temperature, and containing 57 per cent, of H I does not 
correspond to a definite hydrate, 
6. How would you detect iodine, bromine, and chlorine 
when present in solution together ? 
7. How can fluorine be prepared ? 
8. Mention the most remarkable property of H F. 
9. State the general relations which Cl, Br, I, and F exhibit 
amongst themselves. 
Lesson XII. Sulphur and Sulphurous Acid. 
1. State the different compounds in which sulphur is met 
with in nature. 
2. Name some of the chief properties of sulphur. 
3. Write down the names and symbols of the compounds 
of sulphur, oxygen, and hydrogen. 
4. How is sulphuric dioxide prepared ? How can it be 
liquefied ? 
5. How many cubic centimetres of sulphuric dioxide at o° 
and 760 mm. can be got by the use of 12 grms. of copper, and 
how many grms. of sulphuric acid will be needed ? 
6. How is real sulphurous acid formed from sulphuric di- 
oxide ? Explain the constitution of the salts termed sulphites. 
7. How does sulphurous acid act as a bleaching agent ? 
Lesson XIII. Sulphuric Acid and Sulphuretted 
Hydrogen. 
1. How is sulphuric trioxide prepared, and what are its 
properties ? 
2. Describe the decompositions by which sulphuric acid is 
prepared in the leaden chamber. 
3. How many tons of chamber-vitriol, containing 70 per Elementary Chemistry. 
357 
cent, of real acid (H2 SO4), can be prepared from 250 tons of 
pyrites, containing 42 per cent, of sulphur ? 
4. What is meant by the term “ molecule ” as distinguished 
from “ atom ? ” 
5. How many grms. of oxygen can be obtained by the de- 
composition of 450 grammes H2 S04 at a red heat ? 
6. Explain what is meant by the terms “ monatomic ” and 
“ di-atomic.” 
7. How would you detect the presence of sulphuric acid ? 
8. What is the composition of sodium hyposulphite ? 
9. How is sulphuretted hydrogen prepared ? 
10. Explain how this gas may be used for the separation 
of the metals into groups. 
11. Point out the relations existing between the oxygen and 
sulphur compounds. 
Lesson XIV. Silicon, Boron, &c. 
1. Mention the chief properties of selenium and tellurium. 
2. How is silicon prepared ? 
3. What names does the substance Si 02 go by ? 
4. How can we obtain (1) soluble and (2) insoluble silica ? 
5. How is silicic tetrafluoride prepared ? 
6. Where does boracic acid occur ? 
7. What is the composition of borax ? 
Lesson XV. Phosphorus Compounds. 
r. Whence do animals ultimately get the phosphorus which 
they need ? 
2. How is phosphorus prepared from bone-ash ? 
3. Describe the different modifications of phosphorus. 
4. What weight of phosphorus pentoxide can be obtained 
by burning one kilo, of phosphorus ? 
5. How is trihydric phosphate prepared ? Elementary Chemistry. 
358 
6. Write down the formulae of the tribasic sodium phos- 
phates. 
7. How many grms. of sodium metaphosphate can be got 
by heating 100 grms. of microcosmic salt ? 
8. Write down the decomposition which occurs when we 
mix solutions of hydric di-sodium phosphate and silver nitrate 
(Ag NO.). 
9. 4 (H3 POs) = 3 (H3 POi) + PH3. Describe this de- 
composition, and give the properties of the substances 
formed. 
10. How are the chlorides of phosphorus prepared ? 
Lesson XVI. Arsenic Compounds. 
x. How is arsenic separated from its ores ? 
2. Name the oxides of arsenic. 
3. What are the peculiar characteristics of the arsenites 
and arsenates ? 
4. How does ferric oxide act as an antidote to the poi- 
sonous properties of the arsenites and arsenates ? 
5. What is the composition and mode of preparation of 
arseniuretted hydrogen ? 
6. Name the tests by which arsenic can be detected with 
certainty. 
7. Point out the general chemical relations of the arsenic, 
phosphorus, and nitrogen compounds. 
8. Explain fully what is meant when we say that chlorine 
is monatomic, oxygen is diatomic, nitrogen is triato?nic, and 
carbon is tetratomic. 
9. Give examples of compound radicals belonging to the 
monad, dyad, and triad groups. 
10. How is the atomicity of an element or radical denoted ? 
Lesson XVII. The General Properties of the Metals. 
1. Name the metals which are lighter than water. 
2. At what temperature does mercury boil and freeze ? Elementary Chemistry. 
359 
3. Describe the modes in which the metallic ores generally 
occur. 
4. State some of the peculiar properties of the alloys. 
5. Under what typical form may all the oxides be classed ? 
6. What is meant by a metallic salt ? 
7. To what types do the substances Ka SO4, Ba SO<, Ala 
3SO4, Ba N308, Ag3P04, belong ? 
Lesson XVIII. Crystallography. 
1. Give the chief characteristics of crystalline structure. 
2. Distinguish between amorphous and cellular structure. 
3. How is the cube derived from the regular octohedron ? 
4. Explain what is meant by the axes of a crystal. 
5. What are the distinguishing characteristics of the six 
systems of crystallography ? 
6. How is the rhombohedron derived from the double six- 
sided pyramid ? 
7. What is the meaning of isomorphous and of dimorphous 
bodies ? 
Lesson XIX. Metals of the Alkalies. 
1. How was potassium first prepared, and how is it now 
manufactured ? 
2. State the sources of the potassium compounds. 
3. How is caustic potash obtained ? 
4. Describe what happens when gunpowder is burnt. 
5. Supposing that the decomposition is a simple one, how 
many cbc. of (1) carbonic oxide and (2) of nitrogen gas at 0° 
and 760 mm. will be given off by burning one gramme of 
English musketry powder ? 
6. Name the characteristic tests for potassium salts. 
7. What are the sources of the sodium compounds ? 
8. Describe the salt-cake process. 
9. How many tons of vitriol containing 72 per cent, of Ha 360 
Elementary Chemistry. 
SO4 will be needed to convert 100 tons of salt into salt-cake, 
and how many tons of this latter will be formed ? 
10. How many tons of aqueous hydrochloric acid contain- 
ing 30 per cent, of HC1 will be formed in the preceding 
reaction ? 
11. Describe the decompositions by which salt-cake is con- 
verted into soda ash. 
12. Required 500 tons of soda-crystals, what will be the 
weight of salt and pure sulphuric acid needed ? 
13. How were the two new alkaline metals discovered ? 
14. Explain the analogy in constitution existing between 
the potassium and ammonium salts. 
Lesson XX. Metals of the Alkaline Earths and 
A luminium. 
1. What is the composition of slaked lime ? 
2. Describe the uses of lime in agriculture. 
3. How can temporarily hard water be softened ? 
4. Name the commonest minerals containing barium and 
strontium. 
5. How can oxygen gas be prepared from barium dioxide, 
and how can this process be rendered continuous ? 
6. Mention the distinguishing reactions of the compounds 
of calcium, strontium, and barium. 
7. How is metallic aluminium prepared ? 
8. What is the meaning of a mordant ? 
9. Calculate the percentage composition of common alum ? 
10. Give a short account of the composition and properties 
of the different kinds of glass. 
11. How are colored glasses obtained ? 
12. How is common earthenware glazed ? 
Lesson XXL Magnesium, Zinc, Manganese. 
I. Find the formula of a salt having the following per- 
centage composition : Elementary Chemistry. 
361 
Magnesium .... 976 * 
Sulphur 13-01 
Oxygen 26-oi 
Water 51-22 
lOO’OO 
2. How can these magnesium salts be distinguished and 
separated from those of calcium ? 
3. State the method employed to extract zinc from its ores. 
4. How many grms. of crystallized zinc sulphate can be 
got from 1,000 grms. of blende ? 
5. State the composition of the several manganese oxides. 
6. How many litres of oxygen at 120 and under the pres- 
sure of 750 mm. can be got (1) by heating 500 grms. of man- 
ganese dioxide, and (2) by treating the same weight of the 
same oxide with sulphuric acid ? 
7. What tests would you employ to detect the presence of 
the compounds of zinc, cadmium, and manganese ? 
Lesson XXII. Iron. 
1. Mention some of the most important physical properties 
of iron. 
2. How is ferrous sulphate obtained ? How many tons of 
crystals can be obtained by the slow oxidation of 230 tons of 
pyrites containing 37-5 per cent, of sulphur ? 
3. What is the composition of red haematite and specular 
iron ore ? 
4. How can the ferrous and ferric salts be distinguished ? 
5. Describe the manufacture of cast-iron from clay iron- 
stone. 
6. What chemical changes go on in the processes of “ refi- 
ning ” and “ puddling ? ” 
7. How do cast-iron, steel, and wrought-iron differ in their 
composition ? 
8. Describe (1) the common method for making steel, and 
(2) that known as Bessemer’s method. 362 
Elementary Chemistry. 
9. 3'285 grms. of pure iron wire are burnt in excess of 
oxygen and in chlorine gases ; required the weight (1) of 
oxide, and (2) of chloride formed. 
10. What is the cause of difference in the appearance and 
properties of “ mottled ” and “ white ” cast-iron ? 
Lesson XXIII. Cobalt, Nickel, Chromium, Tin, &c. 
1. Mention some of the chemical characteristics of cobalt, 
2. How can cobalt and nickel be distinguished by the blow- 
pipe ? 
3. Give the formulae and names of the chromium oxides. 
4. How can we pass from chromium sesquioxide to the tri- 
oxide, and vice versa f 
5. Write down the formulae of the potassium chromates. 
6. What is the constitution and mode of preparation of 
chlorochromic oxide ? 
7. In what form does tin occur ? 
8. How can tin compounds be distinguished ? 
9. What weight of crystallized “ tin salts ” can be prepared 
from one ton of metallic tin ? 
Lesson XXIV. Antimony, Lead., Thallium. 
1. Write down the formulas of the corresponding oxides of 
arsenic and antimony. 
2. How are the two chlorides of antimony prepared ? 
3. How much manganese dioxide, salt, and sulphuric acid 
will furnish chlorine enough to convert 100 grms. of antimony 
into the trichloride ? 
4. Point out the chief distinguishing properties of the bis- 
muth compounds. 
5. Mention the decompositions which occur in the process 
of lead smelting. 
6. Describe the action of lead upon water. 
7. How is white lead manufactured ? Elementary Chemistry. 
363 
8. 100 grms. of lead oxide when reduced to the metallic 
state in a current of hydrogen lost grms. Calculate 
the combining weight of lead. 
9. 4-9975 grms. of lead chloride needed 3-881 grms. of 
metallic silver for complete precipitation. Required the 
combining weight of lead, those of silver and chlorine being 
given. 
Lesson XXV. Copper and the Noble Metals. 
1. How is copper obtained from copper pyrites ? 
2. Calculate the percentage of water contained in crystal- 
lized copper sulphate. 
3. What is the density of mercury vapor ? Does it obey 
the usual law of densities ? 
4. What weight of mercury and corrosive sublimate must 
be taken to yield three kilos, of calomel ? 
5. How is the silver extracted from argentiferous lead ? 
6. 100 parts by weight of silver yield i32-84 parts of silver 
chloride. Given the combining weight of chlorine, required 
that of silver. 
7. What decomposition does silver chloride undergo in the 
light ? 
8. Describe the method used for the extraction of gold. 
9. How can platinum-ore be worked into coherent metal ? 
10. Give the distinguishing tests for copper, mercury, sil- 
ver, and gold. 
Lesson XXVI. Spectrum Analysis. 
1. Describe the phenomenon observed when a source of 
white light is examined by means of a prism. 
2. What peculiarity is observed in the spectra of colored 
flames ? 
3. How does the spectrum of a glowing solid differ from 
that of a glowing gas ? 364 
Elementary Chemistry. 
4. Mention some facts to show the extreme delicacy of the 
spectrum analytical methods, 
5. How can the spectra of the metals be obtained ? 
6. Describe the construction and mode of use of the 
spectroscope. 
7. Explain what is meant by Fraunhofer’s lines. 
8. Describe shortly an experiment to show the reversion 
of the bright line of sodium. 
9. Why does Kirchhoff conclude that iron exists in the 
solar atmosphere ? 
10. How do we know that the fixed dark solar lines are 
not caused by absorption in the earth’s atmosphere ? 
xi. How can we learn the composition of the atmospheres 
of the fixed stars, and why are we in ignorance about the 
composition of the planets ? 
12. State the results of Mr. Huggins’ observations upon 
the spectra of the nebulas. 
Lesson XXVII. Introduction to Organic Chemistry. 
1. Name the two chief peculiarities of the carbon com- 
pounds. 
2. Give examples of monad, dyad, triad, and tetrad ele- 
ments. 
3. Explain what is meant by saturated and non-saturated 
carbon compounds, 
4. Name the chlorine substitution products of marsh-gas. 
5. Explain, with a drawing, the constitution of the mono-, 
di-, and tri-carbon series of saturated compounds. 
6. What is the constitution of the hydrides, chlorides, and 
alcohols of the first three series of carbon compounds ? 
7. What is meant by an organic radical, and by the term 
polyatomic radicals ? 
8. Show that the constitution of the saturated compound 
benzol, C6 He, is different from that of the alcohol group of 
bodies. Elementary Chemistry. 
9. Give examples to show the distinction between an atom 
and a molecule. 
to. How can all chemical changes be represented as double 
decompositions ? 
11. Give examples of bodies (organic and inorganic) formed 
according to the types— 
Hf. H|0,a„d |||n. 
12. To what types do the following substances belong: 
magnesium chloride, sulphuric acid, tribasic phosphoric 
acid, nitric acid, sulphuretted hydrogen, arseniuretted hydro- 
gen ? 
Lesson XXVIII. Organic Analysis, &*c. 
[It will be necessary for the pupil to work out many more 
exercises on the lesson than are here given.] 
1. Describe shortly the process adopted for the estimation 
of the carbon and hydrogen contained in organic compounds. 
2. 0-3059 grm. of a body containing carbon, hydrogen, and 
oxygen, yielded on combustion obooo grm. carbonic acid, and 
07040 grm. water. Required the relation between the number 
of atoms of the component elements, 
3. What is the molecular weight of an acid (mono-chlor- 
acetic) whose silver salt contains 53-6 per cent, of this metal ? 
4. 0705 grm. of an acid yielded on combustion 0761 grm, 
of carbonic acid and 0-136 grm. water ; 0791 grm. of the silver 
salt contained 0-184 grm. silver. Required the formula of the 
acid containing carbon, hydrogen, and oxygen. 
5. How does the determination of the vapor density of an 
organic body serve as a means of ascertaining its molecular 
weight ? 
6. What is the density of ammonia, marsh gas, olefiant gas, 
methyl alcohol, ethyl alcohol ? 366 
Elementary Chemistry. 
7. Describe the two methods employed for determination 
of vapor density. 
8. Required from the following numbers the vapor density 
of a hydrocarbon of the marsh gas series :— 
Globe filled with air at i6°-5 grm. 
vapor “ 140° 7783 “ 
Capacity of globe 115-5 cbc. 
Lesson XXIX, Monatomic Alcohol Group. 
1. Explain the analogy in constitution existing between the 
ethyl and potassium compounds. 
2. Write down the formula for ethyl alcohol, ether, acetyl- 
acetate, aldehyde, acetamide. 
3. Give the names of the following : 
N /T H ) C2H3O C2H5 ) 
m (g*h5)4 / c2h3o rc2h6 f P> 
' C2H5 3 C2H6 3 
4. What is the chemical change which occurs in the pas- 
sage from an alcohol to the corresponding acid ? 
5. Write down a list of the first eight alcohols with their 
derived acids. 
6. Name the properties and mode of preparation of methyl 
alcohol. 
7. What is the action of sulphuric acid upon methyl 
alcohol ? 
8. By what reactions are we enabled to pass from the 
methyl to the ethyl series ? 
Lesson XXX. Di-carbon or Ethyl Series. 
1. How can alcohol be prepared from its inorganic ma- 
terials ? 
2. How many grms. of alcohol can be completely burnt by 
1,000 litres of oxygen at o° and 760 mm ? Elementary Chemistry. 
367 
3. Give the formulae for potassium ethylate, potassium- 
ethyl-sulphate, and ether. 
4. Describe the continuous etherification process. 
5. Write down in formulae the decomposition by which 
ethyl cyanide yields propionic acid. 
6. How many grms. of ethylamine can be prepared from 
100 of ethyl-cyanate, and how many grms. of potassium car- 
bonate will be produced ? 
7. Write down the formulae of propyl alcohol, propionic 
acid, propyl chloride, butyl alcohol. 
8. How can amyl alcohol be prepared from C5 Hu H ? 
C- H ) 
9. What is the action of chlorine upon q jq” r ? 
10. How can the higher alcohols be prepared from Ameri- 
can petroleum ? 
Lesson XXXI. Compound Ammonias. 
1. Mention the reactions by which the compound alcoholic 
ammonias can be prepared. 
2. Required the percentage of platinum contained in 2 (N 
(C2 H6)3 H Cl) + Pt Cl4. 
3. What is the molecular weight and possible formula of a 
double platinum salt yielding on heating 29-4 per cent, of 
metallic platinum ? 
4. How is tetra-ethyl ammonium hydrate prepared ? 
5. Give examples of primary, secondary, and tertiary 
monamines. 
6. How would you determine the constitution of a com- 
pound ammonia of the composition C3 H9 N ? 
7. What is the formula of tri-ethyl phosphine, and how is 
this substance prepared ? 
8. What is the composition of cacodyl and cacodylic acid ? 
9. How is zinc-ethyl prepared, and what are its chiet 
properties ? 368 
Elementary Chemistry. 
10. Na (C2 H6) + C02 = C3 H5 Na 02; explain this re 
action. 
Lesson XXXII. Oxidized Derivatives of the Alcohols, 
1. Mention the chief reactions by which the fatty acids can 
be formed. 
2. How many grms. of potassium formate can be got from 
500 litres of carbonic oxide at 150 and 745 mm. ? 
3. Required 100 kilos, of C H2 02; how many kilos, of 
oxalic acid are needed ? 
4. What is the formula of formamide ? 
5. How can aldehyde be produced from acetic acid, and 
how can aldehyde be reduced to alcohol ? 
6. Explain what is meant by the acetous fermentation. 
7. What is the composition of red- and iron-liquors ? 
8. How many grms. of glacial acetic acid can be obtained 
from 25 kilos, of potassium acetate ? 
9. How is acetyl acetate (acetic anhydride) prepared ? 
10. Name some of the chlorine substitution products of 
acetic acid. 
11. Give the formulae and mode of preparation of thiace- 
tic acid, acetyl peroxide, acetamide, acetone, acetylene. 
12. Show that by substituting hydrogen in the radical of 
acetic acid by methyl and ethyl we obtain (1) propionic and 
(2) butyric acids. 
13. Point out several methods by which we can pass from 
the di- to the tri-carbon series. 
Lesson XXXIII. Diatomic Alcohols, 
1. What is meant by a diatomic alcohol ? 
2. Mention the chlorine substitution products of ethylene. 
3. Why is ethylene regarded as a non-saturated com- 
pound ? 
4. How is glycol prepared ? 
5. What are the products of oxidation of glycol ? Elementary Chemistry. 
369 
6. How is ethylene oxide distinguished from aldehyde ? 
7. How many grms. of oxygen are required to burn com- 
pletely 100 grms. of tri-ethylene glycol ? 
8. Write down a list of the olifines with their formulae. 
9. What is the name of 12 | 02 ? 
10. Write out the formulae of some ethylene di-amines. 
Lesson XXXIV. Diatomic Acids. 
1. How are the acids of (1) the lactic series and (2) those 
of the oxalic series derived from the corresponding glycols ? 
2. Show that hydrated carbonic acid is the first term of the 
first series. 
3. Write the formula of di-methyl sulpho-carbonate. 
4. How many grms. of oxygen are required to oxidize 100 
grms. of gtycolic to oxalic acid ? 
5. Describe the manufacture of oxalic acid from saw-dust. 
6. Show that lactic acid can be formed from chlor-propionic 
acid. 
7. In what important respect, as regards the formation of 
salts, do lactic acid and its homologues differ from oxalic acid 
and the higher terms of its series ? 
8. How can malic and tartaric acid be obtained from suc- 
cinic acid ? 
9. Describe the several varieties of tartaric acid. 
10. What is the action of hydriodic acid upon tartaric 
acid ? 
Lesson XXXV. Cyanogen Compounds. 
1. Write down the typical formulas for the most important 
cyanogen compounds. 
2. Describe the tests for hydrocyanic acid. 
3. What are the chief points of relationship between the 
cyanogen and the oxalic acid groups of compounds ? 370 
Elementary Chemistry. 
4. How much yellow prussiate of potash, manganese di- 
oxide, and ammonium sulphate can yield 500 grms. urea ? 
5. 50 grms. of urine yielded on analysis 475 cbc. of nitro- 
gen at n° and 754 mm. Required the percentage of urea 
contained. 
6. Write the formulas for cyanuric acid, di-ethyl urea, 
sulphocyanic acid, and cyanamide. 
Lesson XXXVI. Triatomic and Hexatomic Alcohols. 
1. Show the relation in composition existing between propyl 
alcohol, propylene glycol, and glycerine. 
2. Explain the process of saponification. 
3. Explain by typical formula the composition of the 
chlorhydrines. 
C3H3 In* Cs I • 
4‘ (C18 H35 O) H2 ] U3 ’ (C,s H35 O), h \ ’ 
C3 H6 ) n 
(C.8 n360)3 1 U3- 
Name the above bodies. 
5. How is allyl alcohol prepared from glycerine ? 
6. What is the composition ofacroleine ? 
7. What is the constitution of mannite ; and what reasons 
have we for supposing it to be a hexatomic alcohol ? 
8. How are the so-called iso-alcohols prepared ? 
Lesson XXXVII. Sugars and Glucoses. 
1. Give a short description of the preparation and refining 
of cane sugar. 
2. Write down the formula of sucroses and glucoses. 
3. What is meant by right- and left-handed rotatory 
power ? 
4. What is the action of yeast and dilute sulphuric acid 
upon cane sugar ? Elementary Chemistry. 
5. How is dextrose prepared ? 
6. Give a short account of the principal phenomena of 
fermentation. 
Lesson XXXVIII. Starchy Gums, and Glucosides. 
1. How does starch differ in constitution from glucose ? 
2. What weight of dextrine and dextrose can be obtained 
from 1 kilo, of starch by the action of diastase ? 
3. What is the composition of gun cotton, and what advan- 
tages does it offer over gunpowder ? 
4. C2„ H27 N 0„ + 2 H2C> = C7 H6 O + HCN + 2C6 Hl2 
Oe. Explain the above equation. 
5. What is the composition of ink ? 
6. State some of the general characteristics of a glucoside. 
Lesson XXXIX. Group of Aromatic Compounds. 
1. How do we suppose the carbon atoms in benzol are 
arranged ? 
2. Write down the formulas for benzol, toluol, xylol, and 
cumol. 
3. What substances are formed by the replacement of one 
atom of hydrogen in benzol by N 02, N H2 and HO? 
4. Describe the methods employed for preparing aniline. 
’ 5. Required the volumes at o° and 760 mm. of nitrogen and 
carbonic dioxide obtained by the combustion of 216 grms. of 
aniline. 
6. How is rosaniline prepared ? 
7. How can oil of bitter almonds be converted into benzoic 
acid and vice Versa ? 
8. Explain the following :— 
Cl Hs ° | O + C7 H5 O Cl = ° | O + K Cl. 
g. Explain the relation of leucaniline to rosaniline, and of 
white to blue indigo. 372 
Eletnentary Chemistry. 
Lesson XL. Turpentines and Vegeto-alkaloids. 
1. What is meant by physical isomerism ? 
2. What is the general composition of essential oils ? 
3. State the composition and chief properties of naph- 
thalin. 
4. What is the chief coloring matter of madder ? 
5. Name the chief peculiarities of the group of vegeto- 
alkaloids. 
6. What tests may be used to ascertain the presence of 
morphine, brucine, and strychnine ? 
7. Point out the chief properties of quinine, cinchonine, 
and its isomers. 
8. How is theobromine connected with theine ? 
9. Required the molecular weight of an alkaloid whose 
hydrochlorate contains iro per cent, of chlorine. 
Lesson XLI. Albuminous Substances. 
1. In what chemical characters do the albuminous bodies 
differ from chemical compounds ? 
2. How may fibrin, albumin, and casein be separated ? 
3. Describe shortly the composition and properties of blood, 
milk, and bile. 
4. Distinguish between animal and vegetable life. 
5. From what source do animals obtain the energy neces- 
sary for existence, and whence do plants draw the energy 
needed for the organization of their food ? APPENDIX. 
Note.—On the Absolute Weights of Hydrogen, Oxygen, and the other 
Gases. 
In the foregoing pages we have taken the density of Oxygen to be 16 (Hydrogen = 
i), and we have chosen as the standard of absolute weight Regnault’s number 
i’429802 as the weight in grammes of 1 litre of oxygen gas, weighed in the latitude 
of Paris at 0° C., and under a pressure of 760 mm. of mercury, this being generally 
received as the most reliable of this great experimenter’s numbers. Hence we 
adopt -|L- of this, or 0-0893626, as the absolute weight of i litre of Hydrogen measured 
under the same circumstances. Regnault’s experimental number for the weight of 
1 litre of Hydrogen is, however, 0-089578, and if we accept both of these experi- 
mental numbers as correct, the density of Oxygen becomes 13-96 instead of 16. 
In his recent classical researches on the combining weights of the elements (the 
most reliable and accurate determinations which we now possess), Stas concludes 
that the true combining weight, and therefore the true density, of Oxygen is is’gbo 
when H = 1, and thus a remarkable confirmation of the accuracy of Regnault’s 
experimental results is obtained. 
If we wish to calculate the weights of the gases with the greatest possible degree 
of precision, from the best experimental data, we must adopt 1 or 0-089586 
as the unit (or crit/i), and in order to find the weight of 1 litre of the following gases, 
or their gaseous compounds, we must multiply this number by the densities of the 
respective gases, as given in (or obtained from) the accompanying table, and derived 
from the combining weights, as determined by Stas. 
In the third column the experimental densities of the gases are found as they have 
been determined by exact observation ; it will be seen that in some cases these num- 
bers closely agree with those obtained by Stas, whilst in others (especially those of 
the older experimenters) the difference becomes more apparent 
1. 11. in. 
Density Weight of r litre Density 
calculated, at o° & 760 mm. Experimental. 
(Stas). 
Hydrogen .... i’ooo . . 0-089386 . . r’ooo 
Oxygen ..... is’gfio . . i’42g8o2 . . 15’960 Regnault. 
Nitrogen .... i4’oog . . 1-235010 . . 14-023 “ 
Chlorine 33-368 . . 3’i68478 . • ss’343 Bunsen. 
Bromine .... 79’75o . . 7-144483 . . 79978 Mitscherlich. 
Iodine i26’S33 . . ii’335s86 . . 123-83 Dumas. 
Steam 8’g8o . . o’8o4482 . . g’oor Gay Lussac and 
Thenard. 
Ammonia .... 8-304 . . 0-761839 . . 8-614 Biot and Arago. 
Hydrochloric Acid . 18-184 . . 1-629071 . . i8"oo8 “ “ INDEX 
A. 
Acetal, 274 
Acetamide, 277 
Acetates of the alkalies, 275 
Acetic acid, 274 
Acetic anhydride, 276 
Acetines or glycerine ethers, 304 
Acetone, 277 
Acetous fermentation, 275, 314 
Acetyl compounds, 273 
Acetyl acetate, 276 
Acetyl benzoate, 326 
Acetyl chloride, 275 
Acetyl peroxide, 276 
Acetylene, 277 
Acid, definition of, {note) 66 
Acid salts, 108 
Acids, fatty, group of, 270 
Acids, monatomic, table of, 249 
Acids are hydrogen salts, 52 
Acraldehyde, 273 
Acroleine, 306 
Acrylic acid, 306 
Air, composition of, by weight, 46 
Air, a mixture not a compound, 44 
Air, eudiometric analysis of, 44 
Alabaster, 170 
Albumin, 338 
Albuminous bodies, composition of, 339 
Alcohol (common), 254 
Alcohol group, general re-actions of, 246 
Alcoholic fermentation, 314 
Alcohols, diatomic, 280 
Alcohols, hexatomic, 307 
Alcohols, tetratomic, 306 
Alcohols, triatomic, 301 
Alcaloids, vegeto, 332 
Aldehyde, 273 
Aldehyde ammonia, 273 
Alizarine, 331 
Alkaline earth metals, 168 
Alkaline metals, 153 
Allotropic forms of carbon, 65 
Allotropic forms of phosphorus, 127 
Allotropic forms of sulphur, 104 
Alloys of the metals, 146 
Alloys of silver, 214 
Allyl alcohol, 306 
Ally] ether, 306 
Ailyl sulphide, 306 
Alum manufacture, 174 
Aluminium, 173 
Amalgams, 147 
Amido-benzol or aniline, 322 
Ammonia, analysis of, 64 
Ammonia in the air, 49 
A.mmonia, properties of, 62 
Ammonia, density of, 27 
Ammonium theory, 167 
Ammoniacal salts, 167 
Ammonia type, 235 
Ammonias, organic, 264 
Ammonium cyanate, 299 
Ammonium nitrate, 64 
Amorphous structure, 149 
Amorphous phosphorus, 127 
Amygdaline, 318 
Amyl, 263 
Amyl alcohol, 261 
Amyl acetate, 262 
Amyl ether, 262 
Amyl hydride, 262 
Amylaceous bodies and gums, 315 
Analysis by volume of air, 46 
Anhydrite, 170 
Aniline or amido-benzol, 322 
Aniline blue, 323 
Aniline colors, 323 
Aniline colors obtained from coal, 80 
Animal chemistry, 340 
Animals, functions of, 342 
Animal heat, 343 
Animal body, income and expenditure 
of, 344 
Anthracite coal, composition of, 69 
Antichlor, 107 
Antimony, properties of, igg 
Antimony compounds, 199 
Antimoniuretted hydrogen, 201 
Antimony bases, 269 
Aqueous vapor in air, 48 
Aqueous vapor, properties of, 38 
Aromatic compounds, 319 
Arsenates of sodium, 136 
Arsendimethyl, 269 
Arsenic, 133 '376 
Index. 
Arsenic bases, 268 
Arsenic trioxide, 134 
Arsenic pentoxide, 135 
Arsenic, tests for, 137 
Arsenious acid, 135 
Arseniuretted hydrogen, 136 
Atmosphere, the chemical composition 
of, 43 
Atomic theory, 51 
Atomic and molecular formulas, 232 
Atomicity of carbon explained, 229 
Atomicity of the elements, 138 
Atoms, explanation of, 51 
B. 
Balling furnace, 164 
Barium, 172 
Barium dioxide, 172 
Barium salts, 173 
Barometer, construction of, 25 
Baryta, 172 
Bell-metal, 146 
Benzoic acid, 326 
Benzoic alcohol, 325 
Benzoic aldehyde, 325 
Benzoic peroxide, 326 
Benzol, constitution of, 320 
Benzol, properties of, 322 
Benzol, table of derivatives, 320 
Benzoyl benzoate, 326 
Benzoyl chloride, 325 
Benzylamine, 327 
Bessemer steel process, 190 
Bile, constituents of, 341 
Bismuth compounds, 202 
Bismuth-ethyl, 269 
Bitter almonds, 318 
Bitter almonds, oil of, 325 
Black-ash process, 164 
Blast furnace, construction of, 188 
Bleaching properties of chlorine, 87 
Bleaching powder, 92 
Blende, 103 
Blood corpuscles, 341 
Blood, composition of, 341 
Blowpipe flame, nature of, 82 
Bohemian glass, 176 
Boiling points of alcohols and acids, 249 
Boiling point, determination of, 243 
Boiling point of water, 38 
Bones, analysis of, 340 
Boracic acid, 124 
Borax, 125 
Bor-ethyl, 269 
Boron, 123 
Boyle’s law of pressures, 24 
Bromic acid, 97 
Bromine, 95 
Brown oil of vitriol, 111 
Bronze and copper alloys, 209 
Brucine, 336 
Bunsen’s gas-burner, 82 
Butyl alcohol, 261 
Butylene, 284 
Butyl hydride, 260 
C. 
Cacodyl, 269 
Cacodylic acid, 269 
Cadmium compounds, 180 
Caesium compounds, 166 
Caesium and rubidium, discovery of, 221 
Cafeine, 337 
Calamine, 179 
Calcium, 168 
Calcium carbonate, 169 
Calcium oxalate, 290 
Calc spar, 169 
Calculation of vapor density, 243 
Calculation of volumes of gases, 25 
Calomel, or mercurous chloride, 212 
Camphors, 328 
Candle, flame of, 8t 
Cane sugar, 309 
Cannel coal, 69 
Cannel coal gas, 80 
Caoutchouc, 330 
Carbamide, or urea, 299 
Carbon, properties of, 6$ 
Carbon and hydrogen, estimation of, 236 
Carbon compounds, chemistry of the, 227 
Carbon, combining powers of, 228 
Carbon sesqui-chloride, 2S1 
Carbon tetra-chloride, 252 
Carbonic acid, 70 
Carbonic acid decomposed by sunlight, 
11. 
Carbonic acid from lungs, 11, 342 
Carbonic acid (hydrated), 286 
Carbonic acid in air, 47 
Carbonic acid, synthesis of, 73 
Carbonic dioxide, 70 
Carbonic disulphide, 116 
Carbonic oxide, formation of, 75 
Carbonyl (carbonic oxide), 288 
Carre’s freezing machine, 64 
Casein, 339 
Cast iron, 184 
Caustic lime, 169 
Caustic potash, 158 
Caustic soda, 162 
Cavendish’s apparatus, 29 
Celestine, 171 
Cellulose, 317 
Centigrade scale, 21 
Cerium, 144 
Cerotyl alcohol, 264 
Cetyl alcohol, 263 Index. 
3 77 
Corrosive sublimate, 212 
Cressol, 321 
Crown glass, composition of, 176 
Crude wood spirit, 274 
Cryolite, 100 
Crystallization, water of, 149 
Crystallized phosphorus, 128 
Crystallography, principles of, 149 
Crystals of leaden chamber, no 
Cumol, 320 
Cupellation, process of, 213 
Cupric oxide, 209 
Cuprous oxide, 209 
Cyainilide, 298 
Cyanamide, 301 
Cyanic acid, 298 
Cyanogen, properties of, 84 
Cyanogen chlorides, 298 
Cyanogen compounds, 295 
Cyanuric acid, 300 
D. 
Dalton’s atomic theory, 51 
Dark lines in solar spectrum, 223 
Davy lamp, 83 
Decatyl hydride, 263 
Decomposition of water by electricity, 31 
Delicacy of spectrum analysis, 221 
Densities of compound gases, 27 
Density of gaseous elements, 26 
Density of vapors, 242 
Density of water, 36 
Dew, formation of, 49 
Dextrine or British gum, 315 
Dextrose, 311 
Dextro tartaric acid, 293 
Diacetine, 304 
Diacetamide, 277 
Diamond, properties of, 67 
Diamond burnt in oxygen, 73 
Diamines, 284 
Diatomic acids, 286 
Diatomic alcohols, 280 
Diatomic elements, 139 
Dicarbon or ethyl series, 253 
Dichlorhydrine, 304 
Dlethylamine, 265 
Diethyl glycol, 283 
Diffusion of gases, 27 
Di-hydric sulphate, 109 
Di-hydric sulphide, 113 
Di-hydric sulphite, 107 
Dimethyl acetal, 274 
Dimorphism, 155 
Distilled water, 40 
Distribution of the elements, 8 
Distribution of the metals, 142 
Dolomite, 178 
Double decompositions, 53 
Chalk, 169 
Charcoal, properties of, 68 
Chemical analysis, definition of, 12 
Chemical balance, description of, 3 
Chemical combination, examples of, 1 
Chemical symbols, use and meaning of, 
13. 
Chemical synthesis, definition of 12 
China clay, 177 
Chinchonas, alcaloids of the, 336 
Chloracetic acids, 276 
Chloric acid, 93 
Chlor-carbonyl, 288 
Chlorhydrines of glycerine, 303 
Chloral, 274 
Chlorine, discovery of, 86 
Chlorine and nitrogen, 94 
Chlorine, oxides of 91 
Chlorine, properties of 87 
Chlorine and sulphur, 116 
Chlorine, estimations in organic bodies, 
239 . 
Chlor-hydro sulphuric acid, 113 
Chloro-sulphuric acid, 113 
Chloroform, 251 
Choke-damp, nature of, 71 
Chromates, 194 
Chrome yellow, 194 
Chromium compounds, 193 
Cinchonine, 337 
Cinchonidine and cinchonicine, 337 
Citric acid, 294 
Classes of metals, 143 
Classification according to types, 233 
Clay, composition of 175 
Clay-iron-stone, composition of, 186 
Cleavage in crystals, 149 
Coal, nature and composition of, 6g 
Coal gas, composition of, 79 
Cobalt compounds, 191 
Codeine, 33s 
Coefficient of expansion of gases, 23 
Coke, 79 
Collodion, 318 
Colored glasses, 176 
Combining weights, of the elements, 6 
Combining weight, meaning of, 13 
Combustion in oxygen, 10 
Combustion of organic bodies, 236 
Compound alcoholic ammonias, 264 
Compound gases, densities of 26 
Compounds of oxygen and nitrogen, 50 
Compound radicals, 139 
Compound radicals, examples of 230 
Compound ureas, 300 
Condy’s liquids, 183 
Conine, 333 
Continuous spectrum, 220 
Copper, properties of, 208 
Copper salts, 210 
Coral, composition of, 71 378 
Index. 
E. 
Earth’s crust, composition of, 8 
Earthenware manufacture, 177 
Ebullition of water, 37 
Elastic force of steam, 38 
Electrolysis of water, 31 
Elementary bodies, list of, 6 
Elementary and compound substances, 4 
Emerald green, 135 
Energy of animals, source of, 343 
Erythrite, tetratomic alcohol, 306 
Essential oils, 330 
Etching on glass, 101 
Etherification, process of, 256 
Ethyl alcohol, 253 
Ethylamine, 264 
Ethyl ammonias, formation of, 264 
Ethyl carbonate, 260 
Ethyl chloride, 238 
Ethyl compounds, 253 
Ethyl cyanate, 260 
Ethyl cyanide, 258 
Ethyl ether, 252 
Ethyl group, general re-actions of, 246 
Ethyl hydride, 259 
Ethyl nitrate, 259 
Ethyl oxalate, 290 
Ethyl phosphates, 260 
Ethyl sulphide, 259 
Ethylene, 78, 280 
Ethylene alcohol, 281 
Ethylene diamines, 284 
Ethylene dichloride, 281 
Ethylene oxide, 283 
Ethylines of glycerine, 304 
Eudiometric analysis of air, 44 
Eudiometric synthesis of water, 29 
Expansion of gases by heat, 23 
Exceptions to the law of volumes (note), 
232 
F. 
Fahrenheit’s scale, 22 
Fermentations, characters of, 313 
Ferric acid, 187 
Ferric salts, 187 
Ferrocyanogen, 297. 
Ferrous salts, 186 
Fibrin, 339 
Filtration, process of, 40. 
Fire-damp in coal mines, 78 
Flame, nature of, 81 
Flint glass, 176 
Flowers of sulphur, 104 
Fluorine, 100 
Fluorspar, 170 
Food of plants, 344 
F'ormamide, 372 
Formic acid, 272 
Formula, determination of, 239 
Fractional distillation, 245 
Fraunhofer’s lines, 224 
Freezing machine with ammonia, 64 
Freezing of water, 34 
Fuel, composition of, 69 
Fumaric acid, 293 
Fusibility of metals, 141 
G. 
Galena, or lead sulphide, 205 
Gallic acid, 319 
Galvanized zinc, 180 
Gas, coal manufacture of, 79 
Gas burner, Bunsen’s, 82 
Gases, calculation of volumes of, 26 
Gases, expansion of, by heat, 23 
Gases in blood, 341 
Gastric juice, 341 
Gaultheria procumbens, oil of, 327 
Gelatin, 340 
General reactions for production of fatty 
acids, 271 
Glacial acetic acid, 275 
Glass manufacture, 175 
Glucosides, group of, 318 
Glucoses, 312 
Glutin, 339 
Glycerine, 302 
Glycerinic acid, 303 
Glycerine ethers, 304 
Glycogen or animal starch, 316 
Glycocine, 327 
Glycol, 281 
Glycol chlorhydrine, 283 
Glycol diacetate, 283 
Glycolic acid, 288 
Glycols, table of, 285 
Glyoxal, 282 
Gold compounds, 217 
Gold, occurrence of metal, 2x6 
Gold, malleability of, 142 
Gramme, system of weights, 20 
Granules of starch, 316 
Graphite, or plumbago, 67 
Gum Arabic, 315 
Gun cotton, 317 
Gun metal, 146 
Gunpowder, composition of, 159 
Guttapercha, 330 
Gypsum, 170 
H 
Hasmatin, coloring matter of blood, 340 
Hail, formation of, 48 
Hardness of water, 170 
Hartshorn, spirits of, 62 Index. 
379 
Heat, latent, of water, 33 
Heavy spar, 172 
Heptyl alcohol, 263 
Hexagonal system of crystallography, 
rSr 
Hexatomic alcohols, 307 
Hexylene, 284 
Hexyl alcohol, 263 
Higher alcohols, 263 
Higher fatty acids, 278 
Hippuric acid, 327 
Homologous series, 243 
Hydraulic mortar, 169 
Hydric chloride, 88 
Hydric ferrocyanide, 297 
Hydric nitrate, 32 
Hydric peroxide, properties ofj 41 
Hydric persulphide, 115 
Hydriodic acid, 98 
Hydrobromic acid, 96 
Hydrochloric acid, 88 
Hydrochloric acid, density of, 27 
Hydrocyanic acid, 83, 296 
Hydrofluoric acid, 100 
Hydrogen production from water, 15 
Hydrogen, properties of, 14 
Hydrogen, specific gravity of, 17 
Hydrogen type, 233 
Hydrogen, weight of one litre of, 27 
Hygrometers, 49 
Hypobromous acid, 96 
Hypochlorous acid, 92. 
Hypochlorous oxide, 91 
Hyposulphites, 113 
Hyposulphurous acid, 113 
I. 
Illuminating power of coal-gas, 80 
Indestructibility of matter, 3 
Indigo, 328 
Indium, 195 
Ink, 319 
Introduction to inorganic chemistry, 1 
Introduction to organic chemistry, 227 
Inulin, 316 
lodates, 99 
Iodic acid, 99 
Iodine, 97 
Iron compounds, 183 
Iron liquor, 275 
Iron manufacture, 187 
Iron, properties of metallic, 184 
Isatine, 328 
Iso-butyl iodide, 307 
Iso-hexyl iodide, 308 
Isomeric bodies, 281 
Isomorphism, 155 
Iso-propyl alcohol, 303, 308 
K. 
Kaolin, 175 
Kirchoff’s discovery, 224 
L. 
Lactamide, 291 
Lactic acid, 290 
Lactic acid, synthesis of, 291 
Lactic fermentation, 315 
Lactic series of acids, 286 
Lactose or milk sugar, 311 
Lactyl chloride, 291 
Lamp, safety, 83 
Latent heat of steam, 37 
Latent heat of water, 33 
Laughing gas, 58 
Lavoisier on combustion, g 
Laws of chemical combination, 50 
Law of the expansion of gases, 25, 26 
Lead, action of water on, 203 
Lead compounds, 204 
Lead, metallurgy of, 202 
Leaden chamber, process of, no 
Leucaniline, 323 
Levro-tartaric acid, 293 
Levulose, 313 
Light, action on silver salts, 213 
Light, action on chlorine and hydrogen, 
9° 
Lime, 169 
Lithium, 166 
Lithium, occurrence of, 221 
Litre, definition of, 20 
Lixiviation, 163 
Luminosity of flame, 81 
Lunar caustic, 213 
M. 
Madder, coloring matter of, 331 
Magenta, 324 
Magnesium, 177 
Magnesium compounds, 178 
Maleic acid, 293 
Malic acid, 293 
Malonic acid, 291 
Manganese compounds, 181 
Manganese dioxide, 183 
Manganic acid, 183 
Mannite, 307 
Mannitic acid, 313 
Mannite hexastearate, 308 
Marriotte’s law of pressures, 24 
Marsh gas or methyl hydride, 78,231 
Mauve, 323 
Measures, French system, 18 
Melisyl alcohol, 264 380 
Index. 
Melting points of the metals, 141 
Mercaptan, 259 
Mercuric cyanide, 297 
Mercury compounds, 211 
Mercury, properties of, 211 
Metaldehyde, 273 
Metallic chlorides, 14S 
Metallic oxides, 147 
Metallic salts, 148 
Metallic sulphides, 147 
Metals, chemical properties of, 146 
Metals, classification of, 143 
Metals, general properties of, 140 
Meta-phosphates, 131 
Methylamine, 266 
Methyl alcohol, 250 
Methyl-benzol or toluol, 324 
Methyl compounds, 250 
Methyl hydride, 78 
Methyl oxalate, 290 
Methyl-sulpho carbonates, 288 
Metre, length of the, 19 
Metric system of measures, 19 
Milk, composition of, 342 
Milk sugar or lactose, 311 
Mirror plate glass, 176 
Molecular formulae, 232 
Molecular weight, determination of, 239 
Molecule, definition of, no 
Molybdenum, 198 
Monamines, table of, 266 
Monatomic alcohol group, 246 
Monatomic alcohols, table of, 249 
Monatomic elements, 139 
Monatomic series, general re-actions, 278 
Mono-brom-succinic acid, 292 
Monoclinic system, 153 
Monocarbon or methyl series, 250 
Mordant in calico printing, 174, 332 
Morphine, 334 
Mortar, composition of, 169 
Mucic acid, 313 
Mucous fermentation, 315 
Multiple proportion, law of, 50 
Muriatic acid, 89 
N, 
Naphthalin, 331 
Narcotine, 335 
Nascent state, 87 
Natural fats and oils, 305 
Nebulas, spectra of, 226 
Nickel compounds, 192 
Nicotine, 333 
Nitre, 158 
Nitric acid, 54 
Nitric acid, tests for, 55 
Nitric ether, 259 
Nitric oxide, 59 
Nitric pentoxide, 56 
Nitric peroxide, 61 
Nitric tetroxide, 61 
Nitric trioxide, 60 
Nitro-benzol, 322 
Nitro-ferro cyanides, 298 
Nitro-glycerine, 303 
Nitrogen determinations, 238 
Nitrogen, properties of, 42 
Nitro-manmte, 307 
Nitro-toluol, 324 
Nitrous anhydride, 60 
Nitrous ether, 259 
Nitrous oxide, 57 
Nordhausen acid, 109 
Nutntion of animals and plants, 342 
O. 
Oils and fats, natural, 305 
Oil of garlic, artificial, 306 
Oil of mustard, artificial, 306 
Oil of turpentine, 329 
Oil of vitriol, in 
Olefiant gas, 78, 280 
Olefines, table of, 284 
Oleic acid, 305 
Oleines, 304 
Opium, alkaloids of, 334 
Ores, metallic, 143 
Organic analysis, 236 
Organic chemistry, definition of, 227 
Organic compounds, formulae of, 239 
Organic compounds, synthesis o£ 279 
Organic matter in the air, 49 
Organizing action of plants, 342 
Orpiment, 137 
Oxalates of potassium, 289 
Oxalic acid, 289 
Oxalic series of acids, 287 
Oxamic acid, 290 
Oxamide, 290 
Oxidation products of alcohol, 270 
Oxides, metallic, 147 
Oxygen, discovery of, g 
Oxygen, modes of preparation, g 
Oxygen necessary to life, 11 
Oxygen, properties of, 10 
Oxyhydrogen blowpipe, 34 
Ozone, nature 01, 14 
Ozone in the air, 50 
P. 
Palmitic acid, 264 
Palmitines, 304 
Papaverine, 33s 
Paraldehyde, 273 
Paracyanogen, 297 Index. 
381 
Pearl-ash, 137 
Penta-carbon series, 261 
Perbroraic acid, 97 
Perchloric acid, 94 
Periodic acid, 100 
Permanganates, 183 
Petroleum, composition of, 263 
Phosgene gas, 2S8 
Phosphates, constitution of, 131 
Phosphoric acids, 131 
Phosphoric pentoxide, 128 
Phosphoric trioxide, 128 
Phosphorus, 123 
Phosphorus bases, 268 
Phosphorus and chlorine, 133 
Phosphuretted hydrogen, 132 
Photography, use of silver salts in, 213 
Phthalic acid, 331 
Physical properties of gases, 18 
Physical properties of sugar, 310 
Physiological chemistry, definition of, 
. 344 ' 
Piperidine, 333 
Plants, functions of, 342 
Platinum compounds, 218 
Platinum metals, rare, 217 
Platinum, metallurgy of, 218 
Plumbago, 67 
Polyethylene glycols, 283 
Polyglycerines, 305 
Porcelain manufacture, 177 
Potash caustic, 138 
Potassium, 133 
Potassium carbonate, 138 
Potassium chlorate, 12 
Potassium cyanide, 296 
Potassium ferricyanide, 298 
Potassium ferrocyanide, 297 
Potassium salts, tests for, 160 
Potassium, sources of, 136 
Pressure, standard, 26 
Priestley, discovery of oxygen, 9 
Primary monamines, 266 
Propyl alcohol, 261 
Prussian blue, 296 
Prussic acid, 85 
Puddling process, 190 
Pyrites burners, in 
Pyroligneous acid, 27S 
Pyrophosphates, 130 
Pyrotartaric acid, 287 
Q- 
Quadratic system of crystals, 131 
Quartz, 120 
Quick lime, 169 
Quiuidine and quinicine, 337 
Quinine, 336 
R. 
Racemic acid, 293 
Rain, cause of, 4S 
Reaumur’s scale, 22 
Red liquor, 275 
Red lead, 204 
Red phosphorus, 127 
Refining process of iron, rgo 
Refining of sugar, 310 
Regular system of crystals, 150 
Relation of gases to pressure, 24 
Resins and balsams, 330 
Respiration and animal heat, 343 
Rhombic system, 152 
Rock crystal, 120 
Rock salt, 161 
Rosaniline, 324 
Rubian, 331 
Rubidium compounds, 166 
S. 
Saccharic acid, 313 
Saccharine and amylaceous group, 308 
Safety lamp), 83 
Sal-ammoniac, 62, 168 
Salicine, 318 
Salicylic group, 327 
Salt cake process, 163 
Saltpetre, 158 
Salts of the metals, 148 
Saponification, process of, 302, 305 
Saturated compounds, definition of, 228 
Scheele’s green, 135 
Secondary monaraines, list of, 267 
Selenic oxides, 117 
Selenium, 117 
Seleniuretted hydrogen, 118 
Silica, 120 
Silicic dioxide, 120 
Silicic tetrachloride, 122 
Silicic tetrafluoride, 123 
Silicon, 120 
Silver compounds, 214 
Silver, extraction of, from ores, 213 
Soda-ash process, 164 
Soda caustic, 162 
Soda-crystals, 165 
Soda manufacture, 163 
Sodium, 161 
Sodium carbonate, 162 
Sodium chloride, 162 
Sodium ethyl, 270 
Sodium phosphates, 130 
Sodium salts, tests for, 165 
Solar chemistry, 223 
Solar radiations and life, 343 
Soluble starch, 316 
Specific gravity of the metals, 141 
Spectroscope, construction of, 222 382 
Index. 
Spectrum analysis, 219 
Spermaceti, 263 
Sporules of ferments, 314 
Standard gold, 216 
Standard silver, 214 
Stannic salts, 196 
Stannous salts, 196 
Starch, 316 
Steam, decomposition of, 13 
Steam, density of, 27 
Steam, elastic force of, 39 
Stearines, 304 
Steel, manufacture of, 190 
Stellar chemistry, 226 
Strontium, 171 
Structure of flame, 81 
Strychnine, 333 
Strychnos, alkaloids of the, 333 
Substitution products, examples of, 228 
Succinamide, 292 
Succinic acid, 291 
Succinic anhydride, 292 
Sucroses, 309 
Sugar of lead, 203 
Sugar, preparation of, 309 
Sugar, properties of, 310 
Sulphates, constitution of, 112 
Sulphides, metallic, 147 
Sulphocarbonic acid, 288 
Sulphocyanic acid, 300 
Sulphovinic acid, 239 
Sulphur, 102 
Sulphur, preparation of, 103 
Sulphur and oxygen, 103 
Sulphuretted hydrogen, 114 
Sulphuric acid, 109 
Sulphuric anhydride, 108 
Sulphuric dioxide, 105 
Sulphuric trioxide, 108 
Sulphurous acid, 103 
Sunlight, effect on plants, 344 
Sun’s atmosphere, 225 
Superphosphate of lime, 126 
Symbols of the elements, 6 
Synaptase, 318 
Synthesis of alcohol, 230 
Synthesis of fatty acids, 278 
Synthesis of monatomic alcohol series, 
278 
Synthesis of succinic acid, 292. 
Synthesis of water, 31. 
Systems of crystallography, 130 
T. 
Table of alcohols and acids, 249 
Table of elements, 6 
Table of melting points, 141 
Table of simple and mixed ethers, 257 
Table of specific gravities, 141 
Table of weights, in appendix, 373 
Tannic acid, 319 
Tannine, 319 
Tartar emetic, 294 
Tartaric acid, 293 
Tartrates, 294 
Taurin, 341 
Taurocholic acid, 341 
Tellurium, 119 
Temperature, measurement of, 20. 
Temperature, standard, at o° C., 26 
Tension of the vapor of water, 39 
Tertiary monamines, list of, 267 
Tetratomic alcohols, 306 
Tetra-carbon series, 261 
Tetra-ethyl ammonium, 263 
Thallium, properties of, 206 
Thebaine, 335 
Theine, 337 
Theobromine, 337 
Thermometers, construction of, 21 
Thiacetic acid, 276 
Tin, alloys of, 197 
Tin, metallurgy of, 193 
Tin salts, 196 
Titanium, 198 
Tobacco, alkaloid of, 333 
Toluidine, 324 
Toluol or methyl-benzol, 324 
Tri-acetine, 304 
Triatomic alcoho's, 301 
Triatomic elements, 139 
Tricarbon series, 261 
Tri-chlor-hydrine, 304 
Triclinic system, 153 
Triethylamine, 263 
Triethyl-phosphine, 268 
Trihydric phosphate, 129 
Trimethylarsine, 269 
Trl-nitro-glycerine, 303 
Tungsten, 198 
Turnbull’s blue, 298 
Turpentines and camphors, 328 
Types, classification according to, 233 
Type metal, composition of, 200 
U. 
Uranium compounds, 193 
Urea, compounds of, 300 
Urea, synthesis of, 299 
Uric acid, 301 
Uric acid, derivatives of, 301 
Urine, composition of, 342 
V. 
Valeric acid, 262 
Vanadium, 198 Index. 
383 
Vapor of water, tension of, 39 
Vapor density, determinations, 242 
Vegeto-alkaloids, 332 
Volumes, law of organic compounds, 242 
Volumes of gases, 24 
W. 
Water, action of lead upon, 203 
Water, analysis of, 31 
Water, composition by weight of, 33 
Water decomposed by potassium, 15 
Water formed by combustion of hydrogen, 
17 
Water of crystallization, 41 
Water, physical properties of, 35 
Water, synthesis of, 29 
Water type, 233 
Wax, bees, 264 
Wax, Chinese, 264 
Weights, French system of, 20 
Weights and measures, table of, in ap- 
pendix, 373 
White arsenic, 134 
White indigo, 328 
White lead, manufacture of, 205 
Wood spirit, 250 
Woody fibre, 317 
X. 
Xyloidine, 317 
Xylol, 320 
Y. 
Yeast plant, 314 
Z. 
Zeolites, 175 
Zinc, compounds of, 180 
Zinc, extraction of, 179 
Zinc ethyl, 270 
ERRATA. 
Page 131, rst line.—For Quadric read Quadratic. 
Page 324, line 8.—Space between oxidizing and agent