212 Mr. W. Sutherland on the Spontaneous 



817 is 2'2/K) 11 gram ; now the total mass of oxygen filling 

 the other gauge at about '001 atmo is about 1'3/10 4 gram. 

 Thus a conversion of less than a millionth of their mass of 

 gas into ions collected into one of the gauges would explain 

 the strange phenomenon encountered by Baly and Ramsay, 

 if it is allowed that between the isolation of the gauges from 

 one another and the compression into the fine tubes the 

 charge Q got discharged, so that in both fine tubes after 

 compression there was only pure oxygen, 2 . We have also 

 to account for the disappearance of the equal and opposite 

 charge to Q. But it is not worth while occupying space to 

 speculate on these minor matters, as the phenomenon is so 

 important as to entitle it to a thorough experimental investi- 

 gation. 



There are one or two consequences of the spontaneous 

 formation and decomposition of ozone at low pressures which 

 deserve to be touched on briefly. The first is, that as there 

 is no theoretical reason why the presence of nitrogen should 

 suppress the actions which we have been discussing, there 

 ought to be slight departure from Boyle's law in rarefied 

 air ; in fact, let p n and p be the partial pressures of nitrogen 

 and oxygen in the air, then 



p n B = k n ; but p B = k — aB, 

 so that 



(p n +Po)B=pB = k n + k -*B, 



and thus for air the equation is of the same form as for 

 oxygen, but the departure from Boyle's law will make itself 

 conspicuous in a different region of pressure : Bohr found 

 the departure in oxygen from a pressure of 15 millim. down 

 to *7 millim. where the first discontinuity occurred, and so 

 for air it might be looked for from about 75 millim. down 

 to 3*5 millim. where a discontinuity should be expected, but 

 of a different nature from that with oxygen, in fact p 

 becomes constant for a short range of volume, and so 



(p+p )B=pB = k n +p B 



till the region of volume is reached for which a. in oxygen 

 has the smaller value «', and then pB = k n + & — a'B, which 

 lasts until p =2a, at which point all the oxygen will have 

 been changed into ozone, and therefore p n will be 4p x 3/2, 

 seeing that in the atmosphere at 760 millim. j> n = 4-p ; thus 

 the pressure at which Boyle's law will become re-established 

 for the air, now a mixture of nitrogen and ozone, will be 

 13a' or about '715 millim. of mercury. 

 The only accessible data suitable for comparison with these 



