~ in which ¢ and ¢ are to be calculated as above.* 

MECHANICAL ACTION OF HEAT. 587 
already found is sufficiently near the truth, viz., 2°-1 centigrade; so that, in the 
present instance r—x=272°'5 centigrade. 
Then we find the following results when r=7,, and D=D,; 
Metres, Feet. 





(tT — k) FM S = per centigrade degree, . ; : ; : 0°145 0:48 
0 2 
a? P 
(7 ay kK) at. a ” ” ” . . oy . 0 0-150 0-49 
Sum = K, — & = excess of apparent specific heat at constant volume 
above real specific heat, 2 . : : 4 0:295 0:97 
(a) 
(7 — k) Z fs = difference between apparent specific heats at con- 
Sry stant volume and at constant pressure, - 19565 64-19 
Kk, — k = excess of apparent specific heat at constant pres- 
sure above real specific heat, ; 5 . 19860 65:16 


3 of the above quantities are of course the corresponding quantities for FanREN- 
HEIT’s scale. 
- 
Secondly, If the velocity of sound in the gas is given, let this=w. Then we 
know that 
Signe tg eluant vee ub ois’ 9) Yor ioe oA 
in which 
dP. ene oA 1d.A 
eae Yelat ads ABT} tp RAD 
So that from the velocity of sound we can calculate the ratio of the specific heats 
at constant pressure and at constant volume. Let this ratio be denoted by vy, 
and let g 
K, =k +¢; K,=&+4+¢; then 
a Seats 
Mia al a’? 

_¢= Ve 
and Kk = ya ; E : oo 5 (002583) 
(63.) In using the formula (110) for a gas whose pressure is represented by 
the formula, 

V 0 
the integrals may be transformed so as to be taken, with respect to the density, as 
in the preceding article. Thus we obtain 
Peeve Bie nesta 
T) Ve 
* See Appendix, Note B. 
