﻿tu Gaseous Mixtures by Rontgen Radiation. 321 



greater than the possible errors of experiment in the relative 

 ionizations produced by a given radiation. Typical results 

 are given in Table I. 



As the ionization was exceptional, it seemed advisable to 

 directly measure the absorption of X-rays in these two gases. 

 This was done by Mr. Collier, who found the absorption in 

 S0 2 greater than in SH 2 by an amount about equal to the 

 absorption in Q 2 . This result showed there was no violation 

 of absorption laws, and that impurity was not producing any 

 appreciable effect. 



Thus the ionization and absorption in these two gases are 

 in the reverse order of magnitude. The fact would not be 

 remarkable, however, if the secondary rays were not also 

 accounted for. But the secondary corpuscular radiation 

 was all absorbed in both gases with the exception of that 

 from a very thin layer at the boundaries of the ionization- 

 chamber. The resultant effect of this must have been ex- 

 ceedingly small in these two g;ises, and have actually entailed 

 greater loss by the SH 2 than the S0 2 . The difference must 

 have been inappreciable. Again, the fluorescent X-radiations 

 emitted by IS are very absorbable, and must have been more 

 absorbed in S0 2 than in SH 2 , owing to the higher absorbing- 

 power of 2 than H 2 . Finally, though there is the possibility 

 of the energy of fluorescent X-radiation escaping from 2 

 being greater than that from H 2 , the maximum possible 

 difference would again be inappreciable. There seemed, 

 therefore, little doubt of the less absorption in SH 2 being- 

 accompanied by the greater ionization. This, however, by 

 no means proved that ionization is not an atomic phenomenon. 

 For sulphur atoms might emit the same amount of corpus- 

 cular radiation in both gases ; but whereas in SH 2 the 

 corpuscles would be almost entirely absorbed in sulphur, in 

 S0 2 they would be partially absorbed in sulphur and partly 

 in oxygen. Thus the difference might be due to the greater 

 production of ions from sulphur than from oxygen by the 

 absorption of the same amount of energy of corpuscular 

 radiation. This would still leave ionization a strictly atomic 

 phenomenon. 



In order to determine if ionization is truly atomic and 

 at the same time to further test the observed absence of 

 proportionality of ionization and absorption, experiments 

 were made on the ionization in mixtures of SH 2 and O a at 

 equal partial pressures and of S0 2 and H 2 . Jn these mixtures 

 we have the same elementary constituents in the same 

 proportion. They therefore absorb all radiations to an equal 

 extent, and each constituent is subject to the same radiation 

 in the two cases. The results show a decided difference 



