The High-Frequency Spectrum of Tungsten. 369 



The reflexion angles are believed to be accurate within +3'. 

 The wave-lengths are calculated from the formula 



X = 2^sin0, 



where d is taken as 2'814 x 10~* 8 cm. 



Reflexion angle. 



Wave-lengths X 10 s cm. 



Intensity. 



15° 13' 



1477 



Strong. 



13 c 29' 



1-312 



Weak. 



13° 19' 



1-296 



Strong. 



13° 07' 



1-277 



Weak. 



12° 55' 



1-258 



Strong. 



11° 24' 



1113 



Strong. 



11° 05' 



1-082 



Weak. 



It will be noticed from this table that the first line 

 corresponds to the only line in the spectrum of tungsten 

 referred to by Moseley, which he designates the a line of 

 the "L" series. The lines X 1'296 and X 1-258 fill exactly 

 the gaps in the curves as given by the beta and gamma lines 

 of this series for the elements from zirconium to gold. 

 X 1*277 is probably the <j) radiation. It will be interesting 

 to investigate if these elements have also radiations analogous 

 to X 1-312, X 1-113, and X 1-082. 



Extrapolating Moseley's * results as expressed by the 

 relation 



v =c(is-iy, 



where v is the frequency, a constant, and N the atomic 

 number, which for tungsten is 74, we get 0*22 x 10~ 8 cm. 

 for the wave-length of the a line of the " K " series. This 

 wave-length corresponds to a reflexion angle of 2° 18' from 

 rock-salt. The photographs obtained with the thick crystal 

 showed no signs of this line, but a continuous spectrum 

 extended from 4° 54' almost to the edge of the central 

 image. Beyond this band towards the longer wave-lengths 

 was another band much less uniform in intensity, and ex- 

 tending almost to the lines of the "L" series. De Broglief 

 found similar results for "tungsten and platinum (atomic 

 number 78) ; and Maimer t observed in the case of cerium 



* Phil. Mag. xxvii. p. 710 (1914). 



t Comptes Rendus, clviii. p. 177 (1914). 



% Phil. Mag. xxviii. p. 792 (1914). 



Phil. Mag. S. 6. Vol. 30. No. 177. Sept. 1915. 2 B 



