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



477 



propagated through the air and cyanogen mixture, so as to meet the 

 detonation- wave .coming in the contrary direction before the latter 

 reached the end of the tube. The detonation-wave was then photo- 

 graphed as it met the sound-wave. The photographs clearly show 

 several sound-waves passing through the incandescent gases. 



The rates of these sound-waves have been measured and the corre- 

 sponding temperatures calculated. These values are given in Table III 

 on the assumption that the combustion was complete. 



Table III. 



Number. 



Telocity of sound-waves 

 in explosion of 

 C 2 N 2 + 20. : . 



Calculated temperature. 

 7 for diatomic gas, .1 *41. 

 7 for triatomic gas, 1 "28. 



1st, 



1116 metres per sec. 



4100° 



2nd 



1014 



3330 



3rd 



893 



2530 



It will be seen that the temperature calculated for the first sound- 

 wave (4100°) is in close accordance with that calculated from the 

 reflection-wave in the same mixture (4200°) given in Table II. 



The experiment was next varied by the introduction of a thin iron 

 membrane between the air and the explosive mixture. The shock 

 transmitted through the air from the fulminate struck the flexible 

 plate, and so propagated a wave of small displacement through the 

 explosive mixture. This wave had very little effect on the movements 

 of the gas in the wake of the detonation-wave, but its passage through 

 the luminous gas was plainly marked. The gases were ignited as 

 before, the lengths of the tubes being so adjusted that the first sound- 

 wave met the detonation-wave about 1 metre from the membrane. 



With the mixture C 2 N 2 + Oo three photographs were obtained in 

 which the course of the sound-waves were fairly marked. The mean 

 of several independent measurements made on each photograph gave 

 as the velocity of the sound-wave in the stationary gas as 1250 metres per 

 second. This velocity corresponds to a temperature of 3460° (y = 1*41), 

 a number in very fair agreement with that calculated from the reflec- 

 tion-waves, viz., 3330° (Table II). This agreement indicates that the 

 reflection-waves really travel with a velocity approximately equal to 

 that of sound. 



