OF GASES AND VAPOURS. 205 
: 3 , 1 : 
a the expansion for 1° C., in this case -=..., if we set out 
aa : 336°22 
from the volume at boiling-point. 
k is determined by the formula 
p=ke(l+ad). 
For the boiling-point ¢=0, and under the pressure of one atmo- 
sphere (p = 10333 kilogrammes), the density of the steam 
i 
= —_. = 33¢ le ye 
16962? therefore k = 10333 x 1°6964 = 1°7529 
b is the specific heat with constant pressure when this pres- 
sure amounts to one atmosphere (7.), referred to the unit of weight. 
This specific heat may therefore be calculated from the known 
value of B; we have 
5 — 52555. ke 
a Mia. <2 
which, with the numbers just established, gives 
6 = 1°6869. 
20. The difference of the specific heats with constant pres- 
sure and constant volume is, according to II. in No. 5, = a 
consequently in this case = 0°1394. Consequently the specific 
heat of steam under the pressure of one atmosphere is, the pres- 
sure being constant, = 1°6869, and, the volume being constant, 
= 1°5475. 
The ratio of one to the other is 10901. For any pressure p, 
c = 1687 — 0321 .log 2, 
NT Se WO eal 107, (8.) 
c, = 1548 — 0321. log, 
Po 
The logarithms are Briggs’s, and the specific heats refer to 
units of weight. 
The limit ¢,, equal to 0 (see No. 12), makes its appearance 
here very late, viz. at a pressure approaching closely to 100,000 
atmospheres. 
21. There are very few experiments with the results of which 
the values here found might be compared, and even these de- 
‘serve but little confidence. Benzenberg has found the velocity 
of sound in steam nearly equal to that which results from New- 
ton’s formula. This indicates that < must be very nearly =1. 
1 
VOL. IV. PART XIV. Q 
