82 
THE IMPORTANT DISCOVERIES OF GAY LUSSAC. 
first of these laws is, that all compounds, so 
long- as they retain their characteristic pro- 
perties, contain the same constant proportion 
of constituents with the most rigid accuracy, 
no variation ever taking place ; thus nitrate 
of potash, under all circumstances, and in all 
situations, consists invariably of 54 parts of 
nitric acid and 48 of potash. Water consists 
of one part by weight of hydrogen and eight 
of oxygen. Carbonate of lime, whether as 
found in nature, or formed by art, always 
contains 43.2 carbonic acid andSG.S lime ; and 
were these elements to unite in any other 
proportions, some new compound difl’erent 
from carbonate of lime would be formed. 
The truth of this law is universally admitted. 
In fact, without such a law to determine and 
preserve those fixed proportions in the con- 
stituents of bodies, there could not be that 
regularity and uniformity in their composi- 
tion which we invariably find to exist. The 
second law is, that, when two bodies combine 
in different proportions, these proportions are 
always the product of the multiplication by 
1^,2, 3, 4, &c. of the smallest quantity oY 
one of the bodies, the quantity of the other 
remaining the same ; thus supposing there 
exist four compounds of oxygen and manga- 
nese, and that the least oxygenated of these 
compounds is formed of 100 parts of manga- 
nese and I4 of oxj'^gen; another compound 
will consist of 100 parts of manganese and 
14 + 2 of oxygen ; the third compound of 
loo parts of manganese, and 14 4- 3, &c. 
There are three compounds of lead and oxy- 
gen ; the first consists of 104 lead -{- 8 oxy- 
gen ; the second of 104 lead ~j~ 12 oxygen ; 
the third of 104; lead ■\r 16 oxygen: 
here the quantity of lead being given, the 
quantities of oxygen are as thenumbers 1, 1^,2. 
This law is often called the law of multiples. 
The same may be thus expressed ; when any 
two substances, A and B, unite chemically in 
two or more proportions, the numbers repre- 
senting the quantities of B combined with the 
same quentity of A, are in the ratio of 1, 2, 
3, 4, &c. ; that is, they are multiples of the 
smallest quentity of B with which A can 
unite. With respect to this law we may 
observe, that w'hen any compound such as A 
+ D, containing several proportions of A 
combined with a given quantity of B, i.s de- 
composed, if the entire of A is not separated, 
only a defiinite proi ortion of it is removed at 
a time ; nor are we to suppose that the por- 
tion of A, so removed, is derived, from the 
entire compound A + B, but only from a part 
of it. This same of multiples has been 
proved by M. Gay Lussac to hold good also 
in gaseous combinations, which he has clearly 
pointed out to take place in simple ratios of 
volume, and in such a manner as that their 
condensation also bears a simple ratio to their 
original volume ; this may be illustrated by 
the following table : 
200 vols. hydr. gas unite with 100 vols. oxygen 
'^00 ditto 100 azote 200 ammoniacal gas. 
100 ditto 100 chlor. 200 hydr. chlor. acid. 
100 azote 50 oxyg. 100 protox. azote. 
lOo ditto lOo ditto 200 deutox. azote. 
loO ditto 150 ditto hypo nitrous acid. 
100 ditto 200 ditto nitrous acid. 
100 ditto........ 250 ditto nitric acid. 
Thus if we suppose that two gases unite fa 
different proportions, and that the quantity 
of the one is constant, the quantities of the 
other will be such, that the smallest, which 
may be considered as the first, will be con- 
tained a certain integral number of times, 
whether in volume or weight in the following ; 
The combinations of azote with oxygen, five 
in number, may serve as an examnle, by tak- 
ing the quantity of azote as constant : all con- 
tain 104 parts of azote, but the first contains 
50 of oxygen; the second 100; the third 150; 
the fourth 200 ; the fifth 250 ; so that the 
quantity of oxygen in the first is half that in 
the second ; one-third ; of that in the third ; 
one-fourth of that in the fourth, &c. 
whether in volume or in weight- Now 
as several liquids and solids may be con- 
converted into gases, and as this may be done 
by the application of a sufficiently intense 
heat, it is quite natural to suppose that these 
laws of combinatii-n are also applicable to 
bodies of this kind : a fact which several 
experiments tend to prove : thus, when two 
bodies, A and B, combine together to form 
the two bodies C and D, it generally happens 
that.-the quantity of A being the same in C 
and D, that of B in C is to that of B in I) as 
1 to 2, or to 3, or to 4. It is, however, im- 
portant to remark, that though there exist 
relations between the weights of the several 
proportions of any gaseous body, as oxygen, 
which may unite with any solid, as manganese, 
there exists no relation between the weight 
of the oxygen and that of the metal ; thus it 
cannot be said that 10, 14, 16, &c. grains of 
oxygen must combine with 100 grains of 
manganese ; the law is restricted to express 
that lOO grains of metal combining with 14 
grains of oxygen, if it be possible to form 
other combinations between these two bodies, 
100 grains of manganese will unite with a 
quantity of oxygen which will be 1^, 2, 3, 4, 
5, or six times as much as the 14 grains. The 
ca.'se is different when instead of establishing 
a relation between the weights of bodies, we 
establish it between their volumes ; for then 
it is observed, not only that there are simple 
relations between the ditferenl volumes of 
the body A, which combine with a volume 
of the body B, but also that there exist re- 
lations between the respective volumes of A 
and B. This we may illustrate by an exam- 
ple'. 100 cubic inches of azote unite with 50 
of oxygen to form a new body ; here the 
oxygen is one half the azote. 100 azote 
unite with lOO oxygen to form another body ; 
we have a ratio not only between the res- 
pective volumes of the azote and oxygen, 
(a ratio of equality,) but also between the pro- 
portions of oxygen in the two compounds, the 
latter containing twice as much oxygen as 
the other. Again, JOO azote combine with 
150 of oxygen (three times as much as the 
first) to form a third compound. 100 azote 
combine with 200 of oxygen to form a fourth, 
and so on. M. Gay Lussac, to whom we 
owe the discovery of this law, has also de- 
monstrated that when, in consequence of 
combination, the volume of the gases is 
condensed, the condensation bears a simple 
ratio to the volumes of the gases, or rather to 
the volume of one of them. Thus 
