1094 



Mr. D. Coster on the Spectra of X-rays 



could not be separated from a/. The last columns give the 

 difference between the square root of the frequency of u i or 

 fti and that of a satellite. These differences are nearly 

 constant but decrease slowly with decreasing atomic number. 



§ 8. Two very remarkable lines are the new lines /3 U and 

 /3 12 . They may be seen on fig. 2 (PL XXIII.). For Ba, Cs, 

 Te, these lines probably do not occur ; they could be detected 

 for the first time for Sb. From In down to Mo they are 

 fairly strong lines which could be easily measured under 

 the microscope. They could be detected also for Nb and 

 Zr, although for these elements they nearly coincide with 75, 

 which is a much sharper line in this region. For Sr and lib 

 they are very faint or perhaps they do not occur at all. 

 Apparently these lines have nothing to do with the lines /3 7 , 

 /3 8 , /3 9 , and f3 l0 which I have previously measured for the 

 heavier elements *. 



On the short wave-length side of <y 1 a new line (77) could 

 be detected. This line is weaker than j3 n and /3 12 and could 

 be observed as early as Ba. It might be supposed that this 

 line forms a relativity-L-doublet with @ u or /9 12 . The differ- 

 ences, however, between the frequency-differences y 7 -/3 n 











Table X. 













Wave-lengths. 



Frequencies. 



Differences . 



A 





fti 



ft. 



77 



0ii 



>i 2 



■ 7r 



Ai-/3 2 1 £»-& 



77-Ti 



41 Nb 



5161 





176-56 





0-081 



42Mo 



4859-7 



4841-7 





187-52 



188-21 





0071 



0095 





45 Rh 



4084-8 



4072-5 



5896-8 



223 09 



223-76 



233-85 



68 



91 



0076 



46Pd 



3867-6 



3856-7 



3676 



235-61 



236-28 



247-87 



65 



86 



86 



47 Ag 



3663-3 



3653-7 



3479-5 



| 248-76 



249-40 



261-89 



66 



87 



85 



48 Cd 



3477-5 



3468-4 



3302 



i 26205 



262-73 



275-98 



67 



88 



66 



49 In 



3304 



3295-9 



3125 



; 275-81 



276-48 



291-57 



68 



89 



81 



50 Sn 



3142-6 



3134-7 



2968-5 



! 289-97 



290-69 



306-98 



69. 



90 



78 



51 Sb 



2993-4 



2985-8 





304-43 



305-20 





67 



89 





56 Ba 





2218 







410-82 





84 



or y 7 -/3]2 and the /Si-« 2 doublet are in most cases greater 

 than the limits of experimental error. As is seen from the 

 last columns of Table X.. /3 n and j3 2 form a screening-doublet, 

 also /9 12 and /S 2 . The same is true for y 7 and y lm Some other 



* (Note added during the proof.) — From a paper recently published 

 by Mr. Wentzel (Annalen der Physik, lxvi. p. 437 (1921)), however, we 

 are inclined to suppose that the lines /3 n and (3 l2 might be connected 

 with the line /3 8 of the heavier elements. 



