338 Observations on the Absorption of ‘{Nov. 
oxygen. In the same way, meerschaum did not sensibly alter, the 
composition of atmospherical air. 
Meerschaum, Charcoal, and Wood, in a Mixture of equal Volumes 
of Azotic and Hydrogen Gases. 
A volume of meerschaum free from air absorbed, from 2:°5 
volumes of such a mixture, 0°61 volume of azote and 0°42 volume 
of hydrogen ; therefore more of the first than of the last. These 
two gases seem to have been rendered somewhat denser by their 
contact in the stone. A volume of box-wood charcoal free from air 
absorbed, from 16 volumes of such a mixture, 3°5 volumes of azote 
and 09 of hydrogen. * A volume of fir-wood free from air ab- 
sorbed, from four volumes of the mixture, 0°34 volume hydrogen 
and 0‘L1 azote. Wood, then, produces just the opposite effect upon 
these gases that meerschaum does; yet the absorption of the mix- 
ture by the wood agrees with its absorption of the gases separately. 
All my attempts, in these experiments, and in others which I do 
not mention, to detect the formation of water, ammonia, or nitric 
acid, were entirely abortive. I employed no other heat to assist me 
but what was disengaged by the absorption of the gases; yet my 
experiments were not sufficiently varied, nor continued long enough, 
to destroy all hopes of meeting with cases in which such a forma- 
tion may take place ; especially when we employ the intermediate 
action of water, and such absorbing bodies as have a chemical aff. 
nity for these products. 
Section Tarrp. 
ABSORPTION OF THE GASES BY LIQUIDS. 
9. Dalton’s Theory. 
That all gases are absorbed by liquids, and that most of them are 
again separated by heat or the diminution of external pressure, has 
been long known. We now possess accurate results respecting the 
rate of this absorption. For a set of careful and regular experiments 
on this subject we are indebted to Dr. Henry, of Manchester. Mr. 
Dalton has a little altered some of these results; and by means of 
them has contrived a theory which not only explains the absorption. 
of gases by water, but by all other liquids ; but it is in opposition to 
most of the results which I have obtained by means of solid porous 
bodies. ; 
According to him, those gases which separate from liquids when . 
the pressure of the atmosphere is removed are merely held in 
mechanical union, and are by no means in chemical combination 
with these liquids. He affirms, further, that water, at a medium 
temperature, and under a medium pressure of the atmosphere, can __ 
* In this experiment the gases and charcoal remained in contact five weeks; but 
after the first day the volume of the mixture was not altered in the least. On im- 
mersing the charcoal in cold water, 2°55 volumes of azote and 0°64 of lydrogen™ 
were driven out. : 
