Scattering of X-rays and Atomic Structure. 



229 



Moseley's wave-lengths for the more homogeneous character- 

 istic X-radiations, and finding the wave-lengths corresponding 

 to the determined values of \/p *. 



As the scattering intensities given in Table II. are relative 

 to the scattering from aluminium, it remained to determine 

 if the amount of radiation scattered from aluminium varied 

 with the wave-length of the radiation. A similar deter- 

 initiation had been made by one of us when paper and air 

 were the scattering substances ; in these cases little or no 

 variation with wave-length had been observed. It was 



Table II. 



[Showing relative intensities of scattered X-radiation of 

 various wave-lengths from several metals. 



X-radiation. 



i Scattering 



from Cu, Ag, 



Sn, and Pb compared 



with that from equal masses 



of Al. 



Approximate 



Approximate 



( S /P)cu 



( S /p)Ag 



(S/P)s„ 



(S/p) Pb 



wave-length. 



Absorbability 



Wp)m- 



Wp)ai 



1 (S/rtAj 



! 



( s /p)ai 



(S/P) A 1 



•9GxlO~ 8 cm. 



13 



i 





5-6 





•91 



11 





3-66 







•63 



3-3 



25 



... 





11-2 



•59 



2-8 





1 





11-5 



•585 



2-7 



i 2-3 



i 







•52 



1-8 



J 21 







90 



•47 



1-3 



1-9 







5-8 



•43 



•95 



! 1-5 







4-4 



•38 



•65 



L-05? 



i 





2-85 



•316 



•37 



j 1-12 







2-65 



•314 



•36 



1-07 



1-37 





21 



•311 



•35 







1-47 





•306 



•33 



... 



1-25 





1-9 



•305 



•32 



1-05 



... | 



... 



1-7 



thought possible that aluminium, an element of higher 

 atomic weight, might show an appreciable variation in 

 scattering through a long range of wave-length. The relative 

 intensities of the primary and scattered beams were therefore 

 compared by means of the ionization they produced in two 

 electroscopes as the wave-length of the primary radiation 

 was varied. The penetrating powers of both primary and 

 scattered radiation were also examined throughout. 



* The wave-length of the most prominent line, the a line, was taken 

 as representing the wave-length of the K radiation sufficiently 

 accurately. The short wave-lengths were ohtained by extrapolation. 



