158 The Rate of Explosions in Gases. 



hand the physical properties of hydrochloric acid more 

 nearly resemble those of carbonic oxide and the elementary 

 gases than those of steam or carbonic acid ; we should 

 expect, therefore, that the specific heat of hydrochloric acid 

 should remain as constant as that of carbonic oxide at high 

 temperatures. 



I am aware that some of the assumptions made in 

 calculating the temperature of the wave-front cannot be 

 strictly accurate. For instance, the high velocities of the 

 molecules in a heated layer cannot be transferred without 

 loss to the molecules of the next layer, or otherwise sound 

 would be propagated in a gas at the rate of the original 

 disturbance. Again, I assume that the whole heat of 

 chemical combination is developed in the wave-front, an 

 assumption that requires the chemical change to be com- 

 pleted within exceedingly small limits of space and time in 

 those cases where dissociation does not occur. It has been 

 suggested that there is not a true wave motion in the 

 explosion, but that the wave breaks and sends forward jets 

 of heated gas which produce secondary waves coalescing 

 and breaking in turn. 



The tentative formula I have proposed must be regarded 

 as nothing more than a working hypothesis. 



In conclusion, I would say that these experiments have 

 amply confirmed the truth of Berthelot's statement that the 

 explosion-wave is a " specific constant " for every gaseous 

 mixture ; that it has been shown that the rate of explosion 

 depends upon the primary reaction occurring, and that the 

 determination of the rate may throw some light on what is 

 now so obscure — the mode in which chemical changes are 

 brought about ; and, finally, that it does not seem impossible 

 that a connexion between the rate of the molecules and 

 the rate of the explosion may be worked out, which will 

 give us some definite information on points of high interest 

 in the theory of gases. 



