Quantity of Gases absorbed by Water , & c„ 41 
The vessel A will thus be detached, and agitation may be easily 
applied ; after which, again screw it into its former place, and, 
on opening the two cocks, the mercury will rise in the vessel A, 
Supply the descent in B by fresh mercury, and proceed as 
before, repeating alternately the pressure and agitation, as long 
as any further absorption takes place. 
A further amendment of the apparatus, would consist in the 
substitution of cocks of some other metal than brass, which, 
however perfect at first, are always injured by the repeated 
action of the mercury. If cocks of glass could be ground suffi- 
ciently tight, metal caps with screws might be cemented to 
them. 
For observing the increased absorption of less condensible 
gases, I found it necessary to substitute a vessel of larger size 
than A, and of the capacity of at least 50 cubical inches. It is 
represented by the dotted lines in Fig. 1, and was furnished 
with a cock and screw at c. As it would have been troublesome 
to have tilled so large a vessel entirely with quicksilver, it was 
filled with boiled water, with the exception of a quantity of 
quicksilver rather exceeding the bulk of the gas employed. The 
gas was admitted, as usual, from a transfer bottle, the mercury 
which it replaced escaping through the cock b. The increased 
pressure was next applied; and the experiment conducted as 
before, except that the agitation was much longer continued. 
The results cf a series of at least fifty experiments, on car- 
bonic acid, sulphuretted hydrogen gas, nitrous oxide, oxygenous 
and azotic gases, with the above apparatus, establish the fol- 
lowing general law : that , under equal circumstances of tempera- 
ture, water takes up, in all cases, the same volume of condensed 
gas as of gas under ordinary pressure. But, as the spaces occupied 
MDCCCIII. G 
