M. CLAPEYRON ON THE MOTIVE POWER OF HEAT. 371 
From the experiments made by several philosophers we are enabled to 
calculate the values corresponding to the boiling point of 4 and - for 
different liquids; we can therefore deduce from them the corresponding 
values of 1 
o ® 1 = eshte 
gp jes |E% 
B&B 2 les -2 SSE T Corre- 
NAMES Te oe aio oS abate a empera- | sponding 
(8 s Bin SBS oSs ture values 
of ee ie ee : Eo f 
anid £8 Cl>SBe | Bsox eee 1 
quids. Sain PleH ee Moe es ebullition. of CG: 
4 wiS 8 B8ouo0'3/SS & 
> os s a aot n ea so > 
Sulphuric Ether... “> | 2280 | 908 | 355 | 1-965 
1 
JUG) 0X0) RR 9519 1°258 207°7 788 1-208 
1 
VALET v4.22. 00 +0 301 0°451 | 543-0 100° 1:115 
2 1 
2 ae Tur \ 35 | 3207 | 768 | 1568 | 1-076 
These results confirm, in a striking manner, the theory that we are 
explaining ; they show that C is slowly augmented with the tempera- 
ture, as has been already stated : we have seen that for ¢ = 0, a = 1-4], 
whence C = 0°7092; this result is deduced from experiments upon the 
velocity of sound. 
We here find, starting from experiments upon the vapour of water, 
for ¢ = 100°, = = 1°115, whence C = 0°8969; C is therefore in- 
creased from 0 at 100° to 0°187, which gives as the mean of the dif- 
ferential coefficient between these two limits 
dC 
— = 0°00187. 
dt i 
The mean of the two experiments performed by MM. De Laroche 
and Bérard gives us, between the limits 22°83 and 96-90, for the mean 
value of ve the quantity 0°002565. 
These two results differ little from each other, and their divergence 
will be sufficiently explained, by reflecting on the number and the va- 
riety of the experiments whence the data on which they are founded 
. are derived. 
i] 
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