8 Professors W: B. and R. E’. Rogers 
different temperatures, yet made known. The experiments of 
Dalton, Henry, Manchester and Saussure, were made almost ex- 
clusively at 60°. The only results, referring to other tempera- 
tures, which we have seen numerically noted, are one by Caven- 
dish at 55° and one by Henry at 85°. According to Cavendish 
the absorption by one hundred volumes of water at 55° is one hun- 
dred and sixteen. In Henry’s experiment the same volume of 
water at 85°, is said to have absorbed eighty-four volumes of the 
e latter result departs very widely from the mean of our 
experiments at 80° and 90°, which is about sixty-six volumes 
instead of eighty-four. The experiment seems to have been 
made with little care and merely to test the effect of a higher 
temperature upon the amount of absorption. The number ob- 
tained by Cavendish in his observation at 55°, corresponds more 
nearly with our results, which, taking the mean of the experi- 
ments at 60° and 50°, would be about one hundred and ten, in- 
stead of one hundred and sixteen, the number which he has given. 
In the more numerous and important experiments at 60°, the 
observed absorption as given by Saussure, is one hundred and six, 
by Henry, one hundred and eight, and by Dalton, one hundred. 
h 
gas than is proper to the normal pressure. 'The concussive move- 
ment, violently compresses the gas at each vibration, and the ad- 
ditional quantity which in these circumstances is promptly taken 
up by the water, is very slow in separating after the quiescent 
pressure has been restored. 
Referring to the arrangement of the preceding table, it will be 
seen that the numbers in the 7th column express the absorption, 
reduced to volumes of dry gas and to the density corresponding 
to p in the 4th column. | The obvious formula for this has already 
been explained. The numbers in the 8th column, represent the 
actual tension of the gas under which the absorption took place. 
These two columns give the direct experimental relation of the 
absorption of dry gas with the tension of the same. But assum- 
ing Henry’s law to be correct, and in the present case it can in- 
volve no sensible error, this relation would be equally expressed 
by the corresponding numbers in columns 4 and 6, Thus while 
it is clearly proved, from the observations at 50°, that under the 
pressure 29'l=p—Jf, 118-4 volumes of dry gas are absorbed, it 
would also be true that under the pressure 29-46 =p, 120 volumes 
of dry gas would be absorbed, for p : V=p—/: ». 
x 
i 
