TJie Rate of Explosions in Gases. 



151 



of the sound wave would be 2,670 metres per second — a rate 

 which is about 2 per cent less than the observed velocity of 

 the explosion-wave. Now, the theoretical velocity of sound 

 is calculated on the assumption that the disturbance is very 

 small ; if the displacements are large the velocity of sound 

 should be higher. Direct measurements of the velocity of 

 sound waves of great intensity have confirmed this anticipa- 

 tion. Under ordinary conditions the rate of the sound wave 

 is to the mean rate of the molecules as "688 : i. If we take 

 the ratio in an explosion as 7 : i the velocity of the sound 

 wave agrees with the observed rate of explosion in this 

 particular case. 



We may now compare the rate of the sound wave so 

 calculated with the velocity of explosion of cyanogen with 

 oxygen (i) in presence of excess of oxygen ; (2) in presence 

 of excess of nitrogen ; (3) of cyanogen with nitrous oxide 

 alone, and (4) in presence of excess of nitrogen ; and lastly,. 

 (5) of cyanogen with nitric oxide ; taking the data furnished 

 by Berthelot's experiments for the quantities of heat evolved. 



Table XVI II. 



The Rate of Explosion of Cyanogen mixtures compared ivith the 

 calculated velocity of somid (S). 



I. Cyanogen with Oxygen. 



2. Cyanogen with Oxygen and Nitrogen. 



