136 



Mr. Harold B. Dixon on 



Berthelot's conclusion that the explosion-wave is inde- 

 pendent of the initial pressure of the gases must, therefore, 

 be modified. At low pressures the rate falls off, but above 

 a certain crucial pressure, which, in the case of hydrogen 

 and oxygen, seems to be about two atmospheres, the velocity 

 is independent of the pressure. 



§4. Berthelot's formula fails for the explosion of carbonic 

 oxide with oxygen or nitrous oxide. This was to be expected 

 if, in the detonation of carbonic oxide in a long tube, the 

 oxidation is effected indirectly by means of steam, as it is 

 in the ordinary combustion of the gas. Measurements of 

 the rate of explosion of carbonic oxide and oxygen in a long 

 tube showed that the rate increased as steam was added to 

 the dr)' mixture, until a maximum velocity was attained 

 when between 5 and 6 per cent of steam was present. 



In the following table the mean results obtained with 

 the dried and with the moistened gases are given : — 



Table V. 



Rate of Explosion of Carbonic Oxide a?id Oxygen saturated with 



Steam at Different Temperatures. 



§5. When electrolytic gas was mixed with an excess of 

 either hydrogen or oxygen the rate of explosion was found 



