X. Appendix to Mr. William Henry’s Paper, on the Quantity of 
Gases absorbed by JVater, at different Temperatures, and under 
different Pressures. (See Page 29). 
Since my Paper was- printed, I have found that the numbers 
assigned in it, as indicating the quantities taken up by water, 
of some of the more absorbable, and of all the less absorb- 
able gases, are rather below the truth. The accuracy of these 
numbers I was led to doubt, by a suspicion that due atten- 
tion had not always been paid, in my former experiments, to 
the quality of the unabsorbed residuum. For, the theory which 
Mr. Dalton has suggested to me on this subject, and which 
appears to be confirmed by my experiments, is, that the absorp- 
tion of gases by water is purely a mechanical effect, and that its 
amount is exactly proportional to the density of the gas, consi- 
dered abstractedly from any other gas with which it may acci- 
dentally be mixed. Conformably to this theory, if the residuary 
gas contain ~, or any other proportion, of foreign gas, the 
quantity absorbed by water will be \, ~, &c. short of the 
maximum. The proof of these propositions would lead me into 
a minuteness of detail, not suited to the present occasion ; I 
therefore hasten to communicate the results of my latest expe- 
riments. 
The report which I have already given, of the quantity of 
Carbonic Acid Gas, absorbed under the ordinary pressure 
of the atmosphere, I find no reason to correct ; but, of Sul- 
phuretted Hydrogen Gas, I have effected a larger absorption 
