it 
MECHANICAL ACTION OF HEAT. 589 
EXPERIMENTAL Data. THEORETICAL RESOLTS. VELOCITY OF SOUND aT 0° CENT. 

PV at 0° C, . By Obser- 
REGNAULT, Ky [Bp Ky [By Theory.! vation. Observers. 
| Feet. Feet. Feet. Feet, Ft. per sec./I"t. per sae: 
Ase 26214:4|0-2379 | 3306) 96:0 | 234-6 /|1:-4094| 1090-4 | 1090-5 | Bravais & Martins. 
1090-1 | Mout & Van Berx. 
i Oxygen, . . | 23710°4 6-2182| 303-2) 86:8 | 216-4 /1-4014|1036-4 | 1049-3 Dutone. 
Hydrogen, . (3788190 |3-4046|4731-0 |1388:°0 |3343:0 |1:4150| 4153-3 |4165-1 | Dutone, 
Carbonic oxide, | 27097-8 |0:2479 | 344-5] 99-25) 245-25 |1-4047| 1106-8 | 1107-0 | Duone. 
Carbonic acid, | 17144-7|0:2169| 300-7) 64:2 | 236-5 |1:2714| 837-55) 858-28) Dutone. 










The real specific heat of carbonic acid gas is 235°5 feet of fall per centigrade 
degree. That of the other gases does not differ from the apparent specific heat 
at constant volume by an amount appreciable in practice. 
VOL. XX. PART IV. 7U 
