Gaseous Mixtures by Rout gen and Corpuscular Radiations. 851 



Table VI. 



Showing that when X-rays are absorbed in a given vapour, 

 the ionization depends on the surrounding gas absorbing 

 the corpuscles from that vapour. 



Partial pressure 

 of C 2 H 5 Br in 

 cm. of mercury. 



Ionization due to 

 C 2 H 5 Br when 

 with air. 



Ionization due to 

 CH.Ur when 

 with SH 2 . 



Ratio of column 3 

 to column 2. 



2 cm. 



3-92 



478 



1-22? 



4 cm. 



8-i e 



952 



1*17 (irregular) 



6 cm. 



12-06 



14-46 



1-20 



10 cm. 



194 



22-9 



M8 



The numbers in column 4 show the ratio of the ionization 

 due to mixing C 2 H 5 Br with SH 2 to that due to mixing with 

 air. In each case the former is the greater of the two, as 

 might be foretold from the results of experiments on the 

 ionizing effect of corpuscular radiations, given in Table II. 

 The results for 4 cm. of C 2 H 6 Br were somewhat irregular, 

 and for 2 cm. of C 2 H 5 Br much more so; consequently in the 

 latter case, although the percentage error cannot be great, 

 we cannot attach much significance to the exact results of 

 calculations of relative absorptions based on the numerical 

 result given. 



Now assuming all X-ray ionization to be due to secondary 

 corpuscular radiation and that energy absorption of such 

 a radiation is proportional merely to the density of the 

 absorbing gas or vapour, we should have expected the ratio 

 of the values given in columns 3 and 2 to be somewhat 

 higher than that actually found. Thus if m 1 and m 2 be the 

 masses of C 2 H 5 Br and air in a mixture, and if c and a be 

 the ionizations in C 2 H 5 Br and in air when alone, and / the 

 fraction of the ionization in either gas due to its corpuscular 

 radiation, then the additional ionization due to mixino- 

 C 2 H 5 Br with air is 



a -/>+/« 



Wlj 



m x -f m 2 



+fi 



m< 



X iT* +/« 



?}2i 



mi+m 2 1*5 J ?72 1 -f-772 2 



(1-5-1). 



The four terms in the above expression represent (1) 

 direct ionization in C 2 H 5 Br ; (2) ionization in C 2 H 5 Br due 

 to corpuscular radiation from C 2 H 5 Br ; (3) ionization in air 

 due to corpuscular radiation from C 2 H 5 Br ; (4) increase in 



