32 Mr. William Henry's Experiments on the 
and the lower cock b was of glass, accurately ground in. The 
vessel was then filled with water which had been long boiled ; 
a lifting valve was screwed on a, the cock being open ; and the 
vessel was placed under the receiver of an air pump, where it 
was kept for some time, the pump being occasionally worked, as 
long as any air bubbles could be seen to arise. The gas under 
examination was next admitted from an elastic bottle, the cock 
b being opened, and a measured quantity of water let out. The 
gas and water were then violently agitated together ; and the 
cock b opened under mercury, which ascended into the vessel. 
The agitation was still continued, observing to preserve the 
same level of mercury without as within the vessel ; and, when 
it rose no higher, the ascent was noted by means of the gra- 
duated scale. The quantity of mercury that had entered the 
vessel, indicated the amount of absorption that had ensued. 
It might, however, be objected, that the water would acquire 
air again, while poured into the vessel ; and I therefore some- 
times used large glass globes, having long necks, accurately 
graduated. These globes, being of very thin glass, were filled 
with boiling water, and inverted instantly in a trough of quick- 
silver. When the water became cold, the mercury was, of 
course, found to have risen partly into the vessel. This por- 
tion was displaced by a measured quantity of gas; and the 
absorption was denoted by the ascent of the mercury in the 
graduated neck. 
The water employed in these experiments was boiled, during 
several hours, in a tin vessel having an aperture barely sufficient 
to allow the egress of the steam, and poured, while boiling hot, 
into glass vessels, which were corked, and tightly tied over 
with bladder. An equable temperature was produced in the 
