High- Frequency Spectra of the Elements. 703 



In view of the fact that the ft radiations of thorium D and 

 actinium D are much less penetrating than those of the 

 Op products, it is somewhat anomalous that the ft rays of 

 radium C 2 (equivalent to Th D and Act D) have exactly the 

 same penetrating power as those of radium C^. Again, 

 although thorium C and actinium C emit no y rays, yet 

 radium C undoubtedly appears to ; for it is improbable that 

 the relatively few atoms of radium C 2 can give rise to the 

 whole of the intense 7 radiation of radium C. A closer 

 examination of these latter points would be of interest. 



In conclusion we wish to express our indebtedness to 

 Prof. Sir E. Rutherford for his kind interest in this 

 research. 



LXXX. The High- Frequency Spectra of the Elements. 

 Part II. ' By H. G. J. Moseley, M.A* 



THE first part f of this paper dealt with a method of 

 photographing X-ray spectra, and included the spectra 

 *of a dozen elements. More than thirty other elements have 

 now been investigated, and simple laws have been found 

 which govern the results, and make it possible to predict 

 with confidence the position of the principal lines in the 

 spectrum of any element from aluminium to gold. The 

 present contribution is a general preliminary survey, which 

 -claims neither to be complete nor very accurate. 



A somewhat different method of photographing these 

 spectra has been developed independently by de Broglie J 

 and by Herveg §. The latter closely confirms the angles 

 given by Moseley and Darwin || for reflexion of Pt rays fron: 

 rselenite. De Broglie finds less satisfactory agreement for 

 the reflexion from rocksalt. De Broglie has also examined 

 the spectra of W and Au, and has obtained for Cu and Fe 

 ^results similar to those given in Part I. 



The general experimental method has remained unaltered, 

 ..and need not be again described. The same crystal of 

 potassium ferrocyanide has been used as analyser throughout. 

 The sharpness of the lines of short wave-length has 



* Communicated by the Author. 

 t Moseley, Phil. Mag. xxvi. p, 1024 (1913). 



% De Broglie, C. R. 17 Nov., 22 Dec, 1913, 19 Jan., 2 Feb., 2 March 

 TL914. 



§ Herveg, Verh. d. D. Pkys. Ges. xvi. p. 73, Jan. 1914. 

 || Moseley & Darwin, Phil. Mag. xxvi. p. 210 (1913). 



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