448 



Professor Harold B. Dixon 



[June 12, 



caused by the addition of an inert gas to electrolytic gas evidently, 

 therefore, depends upon the volume and the density of the gas added. 

 In the following table the retarding effect of oxygen and nitrogen, 

 on the explosion of electrolytic gas, is compared: — 



TABLE III. 



Eate of Explosion of Electrolytic Gas with Excess of Oxygen and 



Nitrogen. 



I think it a fair inference from these facts to conclude, when the 

 addition of a gas to an explosive mixture retards the rate of explosion 

 by an amount proportional to its volume and density, that such added 

 gas is inert as far as the propagation of the wave is concerned, and 

 that any change which it may undergo takes place after the wave- 

 front has passed by — in other words, is a secondary change. 



This principle has been applied to determine whether, in the 

 combustion of gaseous carbon, the oxidation to carbonic acid is 

 effected in one or two stages — an important question, on which there 

 is little experimental evidence. If, for instance, in the combustion of 

 a hydrocarbon, or of cyanogen, the carbon is first burnt to carbonic 

 oxide, which subsequently is burnt to carbonic acid, the rate of the 

 explosion-wave should correspond with the carbonic oxide reaction, 

 in this case the primary reaction ; whereas, if the carbon of these 

 gases burns to carbonic acid directly, in one stage, then the rate of 

 the explosion-wave should correspond with the complete reaction. 



Now, if we adopt Berthelot's formula as a working hypothesis, 

 we can calculate the theoretical rates of explosion of marsh gas, 

 ethylene, or cyanogen : Q) on the supposition that the carbon burns 

 directly to COg, and (2) on the supposition that the carbon burns 

 first to CO, and the further oxidation is a subsequent or secondary 

 reaction. On the first supposition, if 100 represents the rate of 

 explosion of these three gases burning to carbonic oxide, the addition 

 of the oxygen required to burn the gases to carbonic acid should 

 increase the rate of explosion : — 



Marsh Gas. Ethylene. 



Cyanogen. 



Calculated rate of explosion 

 when burnt to CO2 



} 



104 



103 



107 



Whereas if these gases really burn first to carbonic oxide, and the 



