450 Pro/. H. B.Dixon on the Bate of Exj^losions in Gases. [June 12, 



I suggest the following modifications : (1) the specific heats should be 

 taken at constant volume instead of at constant pressure ; (2) the 

 density of the gas should be taken as the mean of the burnt and 

 unburnt molecules, instead of that of the burut molecules alone ; 

 and (3) a correction should be made for the alteration of volume by 

 the chemical reaction, which in some cases increases, in others 

 diminishes, the volume. 



The rates so calculated agree with the explosion rates of cyanogen 

 when burnt to carbonic oxide either by oxygen, nitrous oxide, or 

 nitric oxide ; with the explosion rates of hydrogen and oxygen with a 

 large excess either of hydrogen, oxygen, or nitrogen ; with the 

 explosion rates of ethylene and acetylene with oxygen and a large 

 excess of nitrogen ; and, lastly, with the explosion rates of hydrogen 

 and chlorine with an excess of hydrogen. 



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 connection 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. 



[H. B. D.] 



