SPECIFIC MEAT OF GASES. 
187 
atioof the specific heats, and that consequently the specific 
leat of the air being rOOO by the first process 1 0000 
[hat of the same vo- 
lume of hydrogen 0 8Q3 0’Q033 
ilarbonic acid - 1 ’3 11 - -- -- - 1 2583 
!)xig(‘n - - 0y74 ------ op/0’5 
\zote - - - - 1 OOO 1 UOCO 
Ixide azote - - - T315 ------ 1-3503 
Dlcfiant gas - - - rOSO ------ 1-3530 
Dxide of carbon - - ()’Q83 ------ r0340 
Section IV. 
Specific Heal of the Vapour of IVater compared tvith that of /Hr. 
Aqueous vapour, being an elastic fluid, which cxercisfs Specific Iscai 
1 very marked influence on a great number of the phenomena, to 
t is of importance to have some notions of its specific heatj Uiai of air. 
out we find that it is almost impossible to operate on this fluid 
n a state of purity j for it is essential for experiments of this 
tind, that tne wdiole of the apparatus should be carried beyond 
too®. We must, therefore, when we would seek the specific 
leat of this vapour, have recourse to its mixture with the air, 
ind it is also necessary that the greater part of the apparatus 
oe in a very hot atmosphere, if we wish the vapour to form 
1 considerable quantity of the mixture. Our process will very 
,*asilv apply to this determination. It was, in fact, sufficient 
0 examine comparatively at what term the temperature of the 
.'alorimeter was kept stationary — at first, by a current of 
Iry air, and afterwards by the same current augmented by all 
he va[K)ur which it could dissolve at a determined temperature, 
1 condition which was easily accomplished. 
This is the result of an experiment made with iJiat view. 
'A hot current of dry atmospheric air had raised the tempera- 
ure of the calorimeter to 8‘43 above the ambient air, and 
<ept it stationary at tliat point. The same current, saturated 
A’ith the vapour of water at the temperature of 39°, all other 
rircumstances being absolutely the same, ha» constantly kept 
th« 
