Connexion between ft and 7 Bay Spectra. 



313 



that the value of qhv 2 + A. is very small compared with pliv 1 

 for the actual groups of swift ft rays under consideration. 



We shall now consider whether the experimental evidence 

 supports the view that the energy of the homogeneous 

 groups of ft rays from radium B and radium C are connected 

 with the values of hv, where v is the frequency of one or 

 more of the stronger lines in the ft ray spectrum. 



For convenience of discussion, the frequencies of the 

 stronger lines of the 7 ray spectrum of the penetrating 

 7 rays from radium B and radium C are included in the 

 following table. The value of hv is calculated from the 

 observed frequency, assuming h = 6*55 x 10~ 27 , and expressed 

 in the same form as the energies of the groups of ft rays 

 from radium B and radium in the previous paper of 

 Rutherford and Robinson. The value of e is taken as 

 4*69 x 10" 10 e.s. units — the value deduced directly by Planck 

 from his theory of radiation. The energy hv of the strong- 

 line, which is reflected at 1° from rocksalt, is 1*25 X 10 13 <?, 

 where e is in electromagnetic units. If Millikan's value of 

 e is taken, viz. 4'77xl0~ 10 , the corresponding value of hv 

 is 1-23 Xl0 l3 <?. 



Angles of reflexion and energies of lines in 7-ray spectra 

 of radium B and radium C. 



Angle of 



reflexion from 



rocksalt. 



43' 



1°0' 



1°10' 



1°24' 



1°37' 



1°43' 



2°0' 



2° 20' 



2 C 28' 2° 40' 



3°0' 



3° 18' 



4°0' 

 •312 



4° 22' 



(E=Ai/)H-10 13 « 



1-74 



1-25 



1-07 



•893 



•773 



•728 



•625 



•537 



•507 | -469 



•417 



•379 



•286 



ft-ray spectrum of radium C. 



In the previous paper by Rutherford and Robinson (Joe. 

 cit.), it was shown that the energy of the lines of the /3-ray 

 spectrum of radium C from No. 1 to No. 29 could be expressed 

 approximately by an integral multiple of a unit of energy 

 E = *4384 x 10 13 *>. It was pointed out, however, that in 

 several cases the adjacent lines appeared to be closer together 

 than would be indicated by this difference relation. Since 

 one of the strong lines of the 7 ray spectrum of radium C, 

 reflected at 1°, has an energy of 1*25 xl0 13 £ on Planck's 

 relation, it is to be anticipated on the theory that the energy 

 of a number of lines should show differences of this unit or 

 integral multiples of it. As a special case, the energy of the 

 ft particle itself might be expected to be integral multiples 



