THE NATURE OF CHEMICAL EQUIVALENTS. 
83 
hydrogen 
100 vols. oxyg. with 200 vols. form 200 vis. water. 
luO vols. azote 3u0 vis. do. 200 amcal. gas. 
loo vols. ditto 50 vis oxyg. lOO protox azote 
loo vols- ditto .... loOvls.do. 2oOdeut. azote. 
One or two examples may serve to illu- 
strate the application which may be made of 
these laws of gaseous combination, 
1st. If we desire to know the specific gra- 
vity of a compound gas, suppose ammoniacal 
gas, we know by analysis that 200 vols. am- 
niacal gas result from the combination of 300 
vols, of hydrogen and 100 vels. of azote. Then, 
by adding the specific gravity of azote 0,9722 
to three times the specific gravity of hydro- 
gen 0,0694 + 3= 6,2082, and dividing the 
sum 1,1804 by 2,* * we have the specific gra- 
vity of the compound gas. 
Again, we can determine what are the 
proportions by weight of the elements which 
constitute a compound gas ; it is sufficient 
for this to take the weight of the vols. of the 
simple gases, which enter into tlie composi- 
tion of the compound gas ; for example, the 
weight of ammoniacal gas will be equal to 
0,9f22 (sp. gr. of azote) 0,0694 -1- 3=0.2082 
(:i times the sp. gr. of hydrogen) : — if we 
wmuld reduce these numbers to others more 
simple, we may institute the following 
proportion : 9722 : 2082 : ; lOO ; a?. . * . a == 
9722 of azote combine with 
2'J82 of hydrogen, 100 azote will combine 
with 21,41 hydrogen. 
If we wish to ascertain the composition of 
a gas formed of a gaseous element and of a 
solid body, we shall speedily arrive at it, by 
taking into account the specific gravity of the 
compound gas, that of the elementary gas en- 
tering into its composition, and the condensa- 
tion which the latter gas has experienced in 
combining with the solid body. For example, 
if we wish to know the quantity of hydrogen 
andof sulphur entering into the composition 
of 100 grains of hydrosulphuric acid gas, we 
can ascertain it thus ; we know beforehand, 
that the volume of hydrogen gas contained in 
the lOO grains of hydro sulphuric acid gas is 
equal to that of this gas ; we know also the 
specific weights of hydrogen gas and of hydro- 
sulphuric acid gas ; we then establish the 
following proportion, if we desire to find the 
quantity of hydrogen which it contains ; 
1,1805 : 0,0694 : : 100 ; x = the quantity 
of hydrogen in the gas; that is, the specific 
gravity of the compound gas, 1,805, is to the 
specific gravity of hydrogen, 0,0694 as the 
absolute weight of said compound gas, scil, 
100 grs. is to the absolute weight of the quan- 
tity of hydrogen contained in the 100 grains 
of the hydro-sulphuric acid gas. f Therefore, 
* The process maybe rendered clearer thus : 
specific gravity of the compound would be equal 
0.9722X '.0694-1-3=1.1804 divided by 4=0.2951, 
did the component gases suffer no contraction ; 
but as they contract to one half, the real specific 
gravity is double what it otherwise would be, 
or 0.5902. 
* The principle on which this process depends 
is, that the bulk of any two bodies being given, 
their absolute weights are as their specific gra- 
vities 5 in the present instance it was stated, 
by multiplying the means and dividing by the 
first term, we shall have the weight of the 
hydrogen contained in the 100 grs. of the 
hydro-sulphuric acid gas, and consequently 
the weight of the sulphur. 
Having now considered the doctrine of 
definite proportions, we come to a subject 
not less important, and one which is intimately 
connected with that doctrine, viz. the consi- 
deration of Chemical Equivalents. The na- 
ture of Chemical Equivalents will be best 
illustrated by comparing the relative quanti- 
ties of different bodies which combine together. 
Thus, 8 parts weight of oxygen unite with 
I of hydrogen, 6 of carbon, 16 of sulphur, 36 
of chlorine, 200 mercury. Such are the quan- 
tities of these bodies, which are found to com- 
bine with 8 parts of oxygen ; and when any of 
these bodies combine with each other, they are 
found to combine either in the proportion 
expressed by these numbers, or in multiples 
of them. Thus sulphuretted hydrogen con- 
sists of hydrogen and 16 of sulphur; 30 of 
chlorine combine with 1 of hydrogen to form 
muriatic acid. Protosulphuret of mercury 
consists of 2J9 parts of mercury and 16 parts 
of sulphur ; the bisulphuret of 200 parts of 
mercury and 32 parts of snlplmr. Carbonic 
oxide consists ofo parts of carbon and 8 parts 
of oxygen ; carbonic acid of 6 parts of carbon 
and 16 of oxygen. 4'has, hydrogen being 
taken as the standard, the combining propor- 
tions or Chemical Equivalents of the several 
substances just mentioned are : 
Hydrogen 1, Carbon 6, Oxygen 8, Sulphur 
16, Chlorine 38, Mercury 209. This law of 
equivalents is not confined to elementary 
substances ; compounds also have their com- 
bining proportions, or equivalents, which are 
found by adding together the equivalents of 
the several elementary substances which 
enter in their composition ; thus, the equiva- 
lent of sulphate of potash is ascertained 
by adding together the equivalents of sul- 
phuric acid 4U (16 sulphur-{- 8x3 =24 
= 40) and that of potass 48 (== potassi- 
um 40 + oxygen 8 = 48,) so that its equi- 
valent is 88, The equivalent of muriate 
of soda is 69, as being composed of muri- 
atic acid, 37 X soda 32. This law of 
the combining proportions of bodies may be 
thus expressed : If two bodies combine to- 
gether in definite proportions, the proportion 
in which they enter into combination will 
have a relation to the proportions in which 
they combine with all other bodies ; thus, if 
1 part of hydrogen combine with 8 ofoxygen, 
the same quantities of hydrogen and oxygen 
that the bulk of volume of the hydrogen con- 
tained in lOO grains of hydrosulphuric acid gas 
was equal to the bulk or volume of the 100 grains 
of hydrosulphuric acid gas itself ; therefore, as 
the specific gravity of hydrosulphuric acid gas 
1,1805, is to the specific gravity of hydrogen 
0,0694, so will loO grains of hydrosulphuric acid 
gas be to the absolute weight of a volume of 
hydrogen equal to the volume of said lOO grain?, 
which is the precise quantity of hydrogen con- 
tained in the lOO grains of hydro-sulphuric acid 
gas. 
