Gaseous Mixtures by Rontgen and Corpuscular Radiations, 839 



The relative total ionizations due to corpuscular radiation 

 resemble tlie relative ionizations found by Bragg for the 

 complete absorption o£ the ol rays, though there are marked 

 differences. For a rays, for instance, some of the relative 

 ionizations are air 100, 2 109, C0 2 108, CH 3 I 133. 



Kleeman concluded from his experiments on other vapours 

 that the relative ionization by these two types of rays were 

 almost exactly the same. There is certainly similarity be- 

 tween them, but perfect agreement cannot be said to have 

 been established. 



If we divide the values found by Kleeman for the ioni- 

 zation per centimetre path of a j3 particle by the density of 

 the absorbing substance, then on the assumption that the 

 diminution of energy of a corpuscle per centimetre of path is 

 proportional to the density of the substance traversed (the 

 range of velocity being the same), we get the following 

 relative values of the total ionization : Air 100, 2 106, C0 2 

 105, S0 2 101, C 2 H 5 Br 116, CH 3 I 112. Comparison of these 

 results with those given in Table II. suggests either a complete 

 change in the relative ionizations with the velocity of the 

 corpuscles, which other experiments do not support, or that 

 the absorption of energy is not according to the density law. 

 Kleeman's suggestion that the absorption of ft particles 

 follows the same law as that for « particles, that is, that the 

 relative distances travelled by a and ft particles in different 

 gases for equal losses of energy are probably the same, does 

 not appear to be in harmony with our previous experiments 

 on the maximum distances traversed in different gases by 

 corpuscles. 



One interesting feature of the results given in Table II. is 

 the marked difference between the energy spent in producing 

 a pair of ions in SH 2 and in S0 2 . 



Total Ionization produced by Corpuscular Radiation in 

 Gaseous Mixtures. 



As the ionization produced by corpuscular radiation 

 depends on the particular gas absorbing the radiation, 

 accurate experiments on the ionization produced in gaseous 

 mixtures by corpuscular radiation show us at once on the 

 simplest assumptions what portion of the ionization takes 

 place in each gas. Thus the total ionization in ethyl bromide 

 is 1*5 times that in air. If the total ionization in a mixture 

 of air and ethyl bromide is x times that in air, then 



.*=/(l-5) + (W), 



where /is the fraction of energy absorbed in ethyl bromide. 

 Knowing x we determine f. 



3L2 



