200 HOLTZMANN ON THE HEAT AND ELASTICITY 
14, The specific heat with constant volume is for atmospheric 
rd c, = 0189 — 0°180. log 
0 
This formula would give for a pressure of somewhat more than 
10 atmospheres c, = 0, which cannot be the case; for then the 
smallest quantity of heat added would certainly produce expan- 
sion, and an addition of heat with the retention of the volume 
would no longer be possible with this pressure. It is thence 
evident, that with respect to atmospheric air, the assumptions 
made, viz. that the coefficient of expansion « is constant, and that 
the specific heat is independent of the temperature, even with 
the pressure of ten atmospheres, cause a great difference between 
the results deduced from the formule here given and what ac- 
tually obtains. 
§ 3. Specific Heat and Elasticity of Steam. 
15. The view that steam in the maximum of its force of ex- 
pansion contains a quantity of heat not dependent on this force, 
and consequently likewise on the temperature, has been confirmed 
by the recent experiments of De Pambour. Therefore, if qg re- 
present this quantity of heat, p the force of expansion, and ¢ the 
temperature of the steam, we have, according to No. 7, 
gu 44 bt— Pb te) yy P, 
P 
Now, if we write for p =p, ¢ = 0, that is Gt we reckon the 
temperatures from that point at which the force of expansion of 
the vapours equals yo, or, according to what precedes, equal to 
one atmosphere, consequently from the boiling-point, we have 
g = A, which, subtracted from the last equation, gives 
0o=—bt— A(1 + a) ¢ nif, 
To eipe et aa ae 
or a a 
P ge kel ie ee 
a 
This equation gives the forces of expansion of the vapours of 
water for the temperature ¢, reckoned from the boiling-point. 
If we introduce Briggs’s logarithms, if we express the force of 
expansion in atmospheres, and write M. = = B, in which M is 
the modulus of the Briggs’s logarithm, we obtain 
ee : sf) ans Les) 
Po se t 
