﻿324 Prof. Barkla and Mr. Simons on Ionization 



The ionizations of the two mixtures were determined, the 

 silver fluorescent X-radiation (series K) being used. Both 

 internal faces of the ionization-chamber were then covered 

 with gold-leaf of '00017 gram per square centimetre — gold 

 being used to produce an intense corpuscular radiation — and 

 the ionizations were again determined while the same beam 

 of X-rays was employed. As the absorption by the gold-leaf 

 of the X-radiation used was negligible, the difference 

 between the ionizations in the two cases was due to secondary 

 rays from gold. — or more strictly to the difference between 

 the rays from carbon and from gold. 



Xow the effective radiation so close to a gold radiator is 

 the corpuscular radiation*-. We therefore attribute practically 

 all the difference between the ionizations in the two cases to 

 corpuscular radiation excited by the X-radiation. The 

 following Table gives the results obtained : — 



Tafle II. 



Ionizing radiation : the fluorescent radiation from Ag (series K). 



Gas. 



Observed 



Ionization in 



Chamber with 



C ends. 



Observed 

 Ionization in 

 Chamber with 



Au ends. 



Ionization due to 



Corpuscular 



radiation. 



SH 2 +0, 



Cv38 

 574 



157 

 13o 



9-32 ] 



I ratio 1-20 

 7-76] 



SO -fH 2 





As indicated above, when the ionization-chamber was faced 

 with carbon, there was considerable loss of ionizing corpuscles 

 and of the fluorescent X-radiation from S. The values 

 given in the last column are, however, the relative values of 

 ionization due to the absorption of the same radiation — 

 almost entirely corpuscular radiation. The ratio 1*20 differs 

 little from that produced by X-rays (with the very soft rays 

 set up by these X-rays) in the same two mixtures. 



Thus 



Ionization in (SH9 + O9) i A v , n , 



- — : : ; — ;,., ~ — ^y— by Act X-rays and all seconuary 



Ionization m (SOo 4- Ho) „i n 



rays =1*1 bo. 



Ionization in (SH 2 + 2 ) 



Ionization in (JS0 2 4-H 2 ) 



by corpuscular (electronic) rays 



set up by Ag X-rays =1*20. 



* This may be shown from a knowledge of the fluorescent X-radiation 

 from gold. It has been shown experimentally bv Kleeman (Proc. Rov. 

 ISoc. A, vol. lxxxiv. 1'JlO). 



