154 Mr. Harold B. Dixon on 



atmospheric pressure at the temperature of the oxy- 

 hydrogen flame, it does not seem improbable that dissocia- 

 tion would also occur at the higher pressures and higher 

 temperatures of the explosion-wave. The researches of 

 MM. Berthelot and Vieille, and those of MM. Mallard and 

 Le Chatelier, on the pressures registered in an explosion of 

 gases, have led these investigators to the conclusion that 

 the specific heat of steam rapidly rises with the temperature. 

 The deficiency of "available" pressure, which Bunsen first 

 observed in the explosion of gases, and attributed to in- 

 complete combustion, they consider to be due to an increase 

 of specific heat. Such an increase in the specific heat of 

 steam with rise of temperature would explain the divergence 

 between the observed and calculated rates of explosion of 

 hydrogen with oxygen. And, conversely, it appears to me 

 that the results of the French experimenters might be 

 equally well explained by the temporary dissociation of 

 steam in their explosions. 



That the combustion of pure electrolytic gas is not 

 zvJwlly complete in the explosion-wave has been proved by 

 collecting the residue and exploding it.* In the propagation 

 of the wave the cooling due to expansion is so rapid that 

 some molecules of hydrogen and oxygen, which are unburnt 

 in the wave-front, have not time to combine before they are 

 cooled below the temperature of combination. In a leaden 

 tube, 9 mm. in diameter and lOO metres long, about i per 

 cent of electrolytic gas was found uncombined after the 

 explosion. That this incompleteness of combustion was 

 not due to the cooling effect of the walls was shown b}' 

 making comparative experiments in tubes 4 mm. and \(^ 

 mm. in diameter. Nearly the same percentage of unburnt 

 residue was found in all the tubes, and also when the gases 



•"Incompleteness of Combustion in Gaseous Explosions," by H. li. 

 Dixon and H. W. Smith. Manchester Memoirs [IV.] 2 1888. 



