$6$ Wave-Length of the Sojt y Rays from Radium B. 



Table II. 



Element. 



Radiation. 



Atomic Number. 



Uranium I 



Uranium X t 



Uranium Xo 



a 



P 

 P 



: 



« 



a 

 a 



a 



92 

 90 

 91 

 92 

 90 

 88 

 86 

 84 

 82 

 83 

 82 

 83 

 84 

 82 





Ionium 



Radium 



Emanation 



Radium A 



Radium B 



Radium C 



Radium D 



Radium E 



Radium F 



End product (Lead). . . 



If the general formula of Moseley holds throughout, the 

 frequencies of vibration of the " L " type of radiation for 

 each of these elements can be simply calculated. 



Sin 



ry. 



(1) The 7-ray spectrum of the soft radiations from radium 

 B has been examined by reflexion from the cleavage faces 

 of crystals, and found to consist of a number of well-marked 

 lines. 



(2) The 7-ray spectrum of radium B is found to be of 

 the same general type as that found for platinum and other 

 heavy elements when bombarded by cathode rays. 



(3) Attention is directed to the structure of the spectral 

 lines using an emanation tube as source of radiation, and 

 also to the imperfections of the crystals employed. 



(4) Evidence is given indicating that the spectrum of the 

 soft y-rays spontaneously emitted from radium B, is identical 

 within the limits of experimental error with the spectrum 

 given by lead when the "L ;j characteristic radiation is 

 excited by the bombardments of /3 rays. 



(5) The bearing of these results on the structure of the 

 atom is discussed. 



