of the Phenomena of Dissociation in Gases. 23 



therefore 



0_ 3_2N 2 



(13) 



According to the (a) hypothesis, $ is the mean time during 

 which the molecules exist, and T/ot the mean time during 

 which a liberated atom remains free. According to the (/3) 

 hypothesis, on the other hand, 6 has the former and T the latter 

 meaning. In any case we can easily calculate 0/T or wS/T from 



this equation, since -^ is equal to ,%*_ ;y ^ or example, 

 we have for N 2 4 , according to the experiments quoted in § 2*, 

 Isotherm D.f» = 26-80 mm. . . 0/T=O'O96 



( + 49°-7C.)\ 497-75 1-069 



Isotherm E.Jp = 49-65 mm. . . 0/T = O'O58 



( + 73°-7C.)\ 633-27 0*396 



Isotherm F.J> = 11'73 mm. . . 0/T=O-O16 



( + 99°-8 0.)l 732-51 0-139 



Isotherm H. fp=35-99 mm. . . 0/T = O-Oll 



( + 129°-90 G.) \ 550-29 mm. 0-023 



N 

 At constant temperature we can put C proportional to — . If 



we write C= — r -^> then Z= — </ 5 an( l, according to 

 (12), v ^ 



N 2= ^> (14) 



We have thus obtained the condition (C) of § 1, but only in 

 case 6 depends on the temperature alone, and not on the 

 pressure or volume. If we assume that the course of an 

 impact is not affected by the frequency of occurrence of the 

 impacts, I do not see how this condition relative to 6 is to be 

 reconciled with the hypothesis (a). In that case 6 would 

 indeed depend on the volume, in the same way that the time- 

 interval between consecutive impacts of a molecule does. 

 From the above table, or from Gibbs's equation, regarded as 

 the outcome of experiment, it follows that tvS/T varies greatly 



* For nitrous acid and other dissociable gases the absolute magnitude 

 of T is unknown. We can, however, take for granted that it is not essen- 

 tially different from the length of the same time-period in such gases as 

 oxygen, nitrogen, or nitrous oxide. We shall be within the limits when 

 we say that the mean time of existence of the N 2 0± molecule in the 

 experiments quoted was somewhere between 10~ 13 and 10~ 10 second. 



