118 KEPOKT— 1891. 



their paths, must increase their probabihty of impact, and 

 enormously increase the energy of the blows given, so that 

 the probability of dissociation was increased by molecular 

 attraction, by increasing both the frequency and power of 

 molecular encounters. It was also shown that most of the 

 encounters must be of a grazing character, thus tending to 

 knock off single atoms Avhose inertia was small. These were 

 suggested as the most potent factors in producing dissociation 

 at temperatures so very much lower than the temperatures 

 produced by the combination of the same substances. 



