1902.] of the Flame in the Explosion of Gases. 475 



Table I.— Velocity of Keflection-waves in Gaseous Explosions. 



Mixture of 

 gases. 



Velocity of 

 explosion -wave 

 in metres 

 per second. 



Velocity of 

 reflection-wave 

 in metres 

 per second. 



Eatio of 

 velocities. 



2H 2 + 2 



Ho + N 9 

 2CO + 2 



C 2 1N T 2 + G 2 

 CJN2 + 2O0 

 2CoHo + 50 2 



2820 

 2805 

 1676 

 2728 

 2321 

 2391 



1538 

 1383 

 1078 

 1230 

 1129 

 1133 



1-83 



1- 67 

 1 -56 



2- 22 

 2*06 

 2-11 



of sound in such a gas would therefore give an approximation to the 

 temperature. 



Now the velocity of the reflection-wave in cyanogen exploded with 

 its own volume of oxygen is 1230 metres per second. Assuming y to 

 be unaltered by rise of temperature, and the velocity of sound in air 

 at 0° 0. to be 333 metres per second, the temperature of the gas where 

 the reflection-wave was measured is given by the formula — 



where V is the velocity of sound, and d\ and d the densities of the gas 

 and air respectively under the same conditions. If, on the other hand, 

 we assume (with Le Chatelier) that the specific heat at constant volume 

 of diatomic gases rises with the temperature and becomes 7 at the 

 temperature of this experiment, then the ratio yi falls to 1*29, and the 

 formula becomes : — 



In the case of cyanogen exploded with twice its volume of oxygen, the 

 first reaction probably consists in the burning of the cyanogen to car- 

 bonic oxide, which combines more slowly to form carbonic acid. How far 

 this second reaction is completed when the reflection- wave is measured, 

 it is impossible to decide. On the assumption that the specific heat of 

 nitrogen is constant, and that 0O 2 is 7 '2, the velocity of the wave in 

 the completely burnt mixture indicates a temperature of 4200° C. ; on 

 the assumption that the specific heats of C0 2 and N 2 are 20 and 7, the 

 temperature indicated is 4780° C. On the other hand, if no carbonic 

 acid had yet been formed, the temperature indicated for the mixture 

 of diatomic gases (2CO, 2 , N 2 ) is 2880° C. (C v = 4*8). 



273 = 3330° C., 



273 - 3672° C. 



