NOTE ON THE TUNGSTEN X-RAY SPECTRUM 



(L-SERIES). 



O. B. OVERN 



A rather incomplete report of the work of Dershem on the 

 X-ray spectriim of tungsten has appeared in the proceedings of 

 the Iowa Academy of Science. A complete report is to be found 

 in the Physical R-eview of June, 1918, where he finds this spec- 

 trum to contain 19 lines in the L reg-ion. 



Further experiments have been carried on using the same appa- 

 ratus and method as used by Dershem, but increasing the time 

 of exposure, with the result that six new lines have been dis- 

 covered. 



These results are tabulated below, (giving Dersheurs results 



for reference. 



TABLE 



Wave lengths in lO-'cm. 



Grating constant for rock salt being 2.814xl0-*'cm. 



Accuracy of above figures assumed to be one-tenth per cent. 



The table shows that Dershem 's results have been verified 

 except in the case of one line mientioned below. 



It is the writer's opinion that the wave length 1.419 listed by 

 Dershem as 1.416^ is the second order of the line .706^ found on 

 most of the plates. This line has appeared on only one of my 

 plates sufficiently strong to admit of measurement. This plate 



