Quantity of Gases absorbed by Water , &c. 33 
water, mercury, and gas, except when above 85°, by regulating 
that of the room in which the experiments were made ; and the 
glass vessel, during agitation, was carefully guarded from the 
warmth of the hand. The agitation was continued, till it ap- 
peared, by the scale, to produce no further effect ; and, in the 
absorption of difficultly condensible gases, was repeated at inter- 
vals, during a space of from twelve to twenty-four hours. 
Alterations of the barometer were always observed ; and the re- 
siduary gas measured, or estimated, at a pressure of 29% inches, 
1. Absorption of Carbonic Acid Gas by Water. 
That the temperature of water influences the proportion of 
carbonic acid which it is capable of absorbing, is already known 
as a general fact ; * but the exact amount of this influence has 
not, I believe, been hitherto ascertained. In the course of a 
series of experiments to determine it with precision, I was 
surprised by obtaining results which differed considerably from 
each other, at the same temperature of the gas and water; 
when both were, in different experiments, of like purity ; and 
when the barometer had the same elevation. Of the cause of 
these variations I was not aware, till my friend Mr. Dalton 
suggested, that they probably depended on'the variable amount 
of the residues ; and, on repeating the experiments, with different 
proportions between the gas and the water, this suggestion was 
fully confirmed. Thus, when two measures of carbonic acid gas 
were agitated with one measure of water, the absorption was 
considerably greater than when, to the same quantity of water, 
a less proportion of gas was used. The cause of this diminished 
* See Mr. Cavendish’s experiments in the Phil. Trans. Vol, LVI. p. 163; and, 
Fourcroy’s Systeme, 4to. Tom I, p. 215. 
MDCCCIII. F 
