456 



Dr. C. A. Sadler on Homogeneous 



manner in each case. This is clearly shown in fig. 4, in 

 which the values of k' for the tertiary radiation are taken 

 from a previous paper supplemented by values recently 

 obtained, the scale chosen for k and k' being quite arbitrary. 



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/"lasoriPT/OSI CoEFF/C/ENTS 'ri /!u/miWJM. 



It is thus evident that a very close connexion exists 

 between the emission of corpuscular radiation and the pro- 

 duction of Rontgen radiation of the homogeneous type in 

 the case of the group of elements Cr — Ag. 



This is in entire agreement with the supposition advanced by 

 various investigators -that the production of Rontgen radiation 

 is always accompanied by the emission of negative corpuscles. 



We may even go further and say that there is strong 

 evidence that whenever the characteristic radiation is excited 

 there is always produced a strictly proportional amount of 

 corpuscular radiation. 



Aluminium as Tertiary Radiator. 



In the case of aluminium it was found that traces of iron 

 were present in every specimen that could be obtained, and 

 although in the sample used iron was present only to the 

 extent of *4 per cent., by weight, these traces increased the 

 tertiary Rontgen radiation from aluminium to a considerable 

 3xtent. Correcting for this iron radiation it was found that 

 the radiation of the Rontgen type emitted by aluminium when 

 used as a tertiary radiator was nearly all scattered radiation. 



It has been stated by various experimenters that the radia- 

 tion scattered by a substance of low atomic weight is of the 

 same penetrating power as the incident radiation. Experi- 

 ments now in progress seem to throw doubt on this statement. 



