42 Mr. William Henry's Experiments, &c. 
by every gas are inversely as the compressing force, it follows, 
that zuater takes up, of gas condensed by one, two, or more 
additional atmospheres , a quantity which, ordinarily compressed, 
would be equal to twice, thrice, &c. the volume absorbed under the 
common pressure of the atmosphere. By frequent repetition of the 
experiments, I obtained results differing a little from the general 
principle above stated ; but, for all practical purposes, I appre- 
hend, the law has been announced with sufficient accuracy.* 
In place of the cock a, I cemented, in one experiment, a very 
sensible thermometer. The vessel was next filled with mercury 
through the cock b ; and the tube B being also filled, the cock 
b was shut, and a bottle of carbonic acid gas screwed on. The 
cock b being then opened, the mercury descended, and a mea- 
sured quantity of carbonic acid arose into the vessel A. In the 
same way, a measured quantity of water was introduced. When 
the density of the air was suddenly doubled by a column of 
quicksilver, the mercury in the thermometer, whose bulb was 
still surrounded by the condensed gas, rose about \\ degree. 
On agitating the vessel, till the water encompassed the bulb of 
the thermometer, an elevation of barely \ a degree ensued in 
the temperature of the water. This ascent would probably have 
been greater, if the evolved heat had not been carried off by the 
mercury on which the water floated. 
Manchester, 
Dec. 8th, 1802. 
* That the facts did not, with invariable accuracy, correspond to the law, was 
perhaps, in part, owing to the addition of only z8 inches of pressure ; when, in strict- 
ness, 29I should have been used, or twice the elevation of the mercury in the 
barometer, during each experiment. 
