ge ae et ak ai ee Bd i 
a A a a a a a Sh ala ae 5 a AE SEE Se ee Cea ee ee ee ee 
W. A. Norton—Force of Effective Molecular Action. 489 
hen a gas is allowed to expand under a constant pressure, 
an additional amount of heat is expended in the work of this 
have ate: =u-+su. ach term is a function of the temper- 
ature, ¢; and, differentiating, we have dU=du+sdu. But we 
have seen that du equals the value which sdu par? have if 
n 
k, or mr Were equal to unity. Denote it by e, and we obtain 
i 
dU=e+se. But, since the specific heat under a constant vol- 
ume is proportional to &, ~=F5 and thus s=k This value 
dU 1+k 
of s gives dU=(1+h)e, and sdu=ke; from which aan Ee 
This is ratio of the specific heat under a constant pressure to 
the specific heat under a constant volum 
Ss now subject these theoretical results to the test of 
ure of one volume of oxygen and two ronan 2 hiyds seer 
09277. The ratio of these is 2 ee For Gere vapor w 
have seen that 4=4-93. Thus, ara (= =24) should be the 
value of & for the mixture of oxygen and hydrogen before con- 
densation into aqueous vapor. This result, as will appear in 
the sequel, is in accordance with the results of Professor Pictet’s 
experiments on the liquefaction of oxygen and hydrogen. 
Taking the specific heat of carbon-dioxide, aie) a constant 
26 
volume at 1:26, we have 09277 = 36, and 136x24=3117. 
This is the value af k for this gas under a pressure of one 
atmosphere, and in the condition in which 1t exists as the 
immediate product « of - combustion of carbon. It, is here 
ver tempe ure it rae 
at the same time the spit heat of each molecule sho uld ie 
greater, owing to the increased size of its envelope, and its 
