126 On the Nature of the Motion which we call Heat. 
whence we conclude that 
q('—<2) 
Tae T=pv. ©. dus) rte Vinee CR (10) 
By means of this equation (9) becomes 
: . 
H=7— -p. ge atone By faimitich be 8 
20. Let us now return to the equation (6a) before established, 
and for brevity let us denote the vis viva of the translatory mo- 
tion by K, then 
3 
i 5 PY. 
By combining this with the foregoing equation we obtain 
K "3/e ) 
Z=5(--1): cove oil) 
The ratio of the vis viva of the translatory motion to the whole 
vis viva is thus reduced to the ratio between the two specific 
heats. 
In order to compare with each other the values of the ratio K 
H 
corresponding to different gases, it will be found convenient to 
introduce in the above formula, in place of the specific heats cal- 
culated with reference to the unit of weight, those calculated 
according to the unit of volume, which for distinction may be 
represented by y and 7’. The equation then becomes 
TEL 2° eet . . . . ° . (13) 
If we neglect deviations which arise from an imperfect gaseous 
condition, and conceive all gases to be in the ideal state, then, 
as I have shown in my memoir “ On the Moving Force of Heat*,” 
the difference y'—vy is the same for all gases, Hence the ratio 
2 is inversely proportional to the true specific heat of the gas cal- 
culated according to the unit of volume, 
For those simple gases which manifest no irregularities with 
respect to their volume, and for those compound ones which suf- 
fered no diminution of volume during the act of combination, y, 
K 
and therefore vi also, has the same value. For these gases we 
* Poggendorff’s Annalen, vol. lxxix. p. 394. Phil. Mag. vol. ii. p.1, 
