838 Prof. Barkla and Mr. Philpot : Ionization in Gases and 



the absorption by the gold leaves and that in column 2. 

 Column 5 gives the ratio of ionization in S0 2 to ionization in 

 air due to the complete absorption of a corpuscular radiation. 

 The actual order of experiments was the determination 

 first of ionizations in a number of gases occupying the 

 ionization-chamber in turn when this was faced with carbon, 

 and afterwards of the ionizations in the same gases when the 

 two ends were faced with gold. This ensured more exactly 

 the same experimental conditions for the various gases. 



The range in the velocity of the corpuscles obtainable by 

 means of the homogeneous Rontgen radiations is certainly 

 not very wide, though the absorbabilities may vary enor- 

 mously. The extreme radiations with which accurate results 

 could be obtained were those excited by Se and by Sn 

 X-radiations of series K. According to Whiddington the 

 range of velocity of the most rapidly moving corpuscle in 

 each case is from *8 to 1*2 x 10 10 cm. per second. Using Sn 

 X-radiation (series K) to excite the corpuscular radiation, the 

 ratio of total ionizations in SH 2 and S0 2 was 1*40 ; using Se 

 radiation it was 1*43, which was within the possible error of 

 experiment in agreement with the other. It was evident that 

 within the range of velocity here experimented upon the 

 relative ionizations were independent of the velocity. 



The corpuscular radiations subsequently employed in these 

 experiments were those excited in gold by Ag, Sn, and Ba 

 X-radiations (series K). 



The relative total ionizations produced in nine gases and 

 vapours by the complete absorption of identical corpuscular 

 radiations are given in the following Table. 



Table II. 

 Showing relative numbers of ions produced by corpuscular 

 radiation (set up by a homogeneous X-radiation) when 

 completely absorbed in various gases. 



Gas 

 ionized. 



Relative total ionization 



by corpuscular 



radiation. 



Relative energy of 



corpuscular radiation 



absorbed per pair of ions 



produced. 



Air 



100 

 102 



93 

 110 

 102 

 133 



96 

 150 

 148 



1-00 

 •98 



1-07 

 •91 

 ■98 

 •75 



1-04 

 •67 

 •68 



H 



N" 



o 



CO., 



SH 2 



S0 



C 2 H,Br 



CH j 





