1815.) the Gases by different Bodies: 339 
only absorb gases according to the following law. It absorbs either 
a volume of the gas equal to its own volume, as is the case with 
carbonic acid, sulphureted hydrogen, and nitrous oxide; or to + of 
its volume, as is the case with olefiant gas ; or to ;!, of its volume, 
as is the case with oxygen and nitrous gas; or to =1- of its volume, 
as is the case with azote, hydrogen, and carbonic oxide: so that the 
volumes of absorbed gas in these four divisions may be represented 
by the series (+)°, (1)%, (4)%, (4)3, the volume of water being repre- 
sented by 1.* The same law holds, according to Dalton, for all 
liquids that are not glutinous, as for alcohol, acids, and solutions of 
salts in water; though between the solution and some gases an 
affinity may perhaps exist, as between a solution of an alkaline 
sulphuret and oxygen gas. Finally, he establishes, from.some ex- 
periments of Dr. Henry, that water which has absorbed one gas, 
and is placed in contact with another, always allows as much of the 
first to escape, and absorbs, on the contrary, so much of the other, 
that the mixture of gases, which after this exchange remains behind 
in the water, is exactly in the same proportion as would have been 
produced by the absorption of each of them singly by the water, 
supposing each of the density which it has in the gaseous mixture. 
According to this, water would absorb, from a mixture of two gases 
in equal proportions, only one half of the volume of each which it 
would absorb if the gas were in a separate state. 
_ The following experiments will enable us to examine the accuracy 
of these propositions. 
10. Absorption of unmixed Gases by different Liquids. 
I endeavoured to free the liquids which I used in my experiments 
from air as completely as possible, by long and violent boiling. 
Those which would have been altered or dissipated by the applica- 
‘tion of such a heat, as oils and some salt solutions, were freed from 
air by means of theair-pump. Neither of these methods is capable 
of freeing liquids completely from air; and the more volatile the 
liquid is, they succeed the more imperfectly, because they can only 
be exposed to a lower temperature, and the pressure of the vapour 
which rises from them under the air-pump prevents the escape of 
their air. wn 
To produce a speedy and complete absorption, I put a large 
quantity of those gases whicl: are absorbed only in small quantity 
by liquids, as of azote, oxygen, and hydrogen, with a small quantity 
of the liquid, into a flask, which was furnished with an excellent 
ee stopper, and agitated the flask for a quarter of an hour, 
is is a difficult method, and requires much attention.t With 
Tespect to all the gases of which the liquid absorbs more than 4 of 
* According to him, 100 volumes of water, at the temperature of 61°, absorb 
volumes of the first three gases, 125 volumes of olefiant gas, 3°7 of oxygen 
and azote, and 1°56 of the last three gases, , 
+ More will be said on this subject iv the Appendix. 
x 2 
