﻿and the Theory of Atomic Structure. 555 



dark background. No indication of an emission-line which 

 could be /3 5 was found for these elements. Interpolating 

 between the values of /?-, for W and Ta and the L x discon- 

 tinuities of Eu-Ba we get values which do not coincide with 

 a measured line for any of the elements Lu-Gd. Only in 

 the case of Tb (65) a very faint discontinuity in the blacken- 

 ing of the plate was observed at about 1647 X.U., a value 

 which agrees very well with the interpolated value ; but 

 this discontinuity in the blackening looked more like an 



Table XX. 

 Frequencies. 



ft 



& 



ft. 



47 Ag... 



48 Cd... 



49 In ... 



50 Sn ... 



51 Sb ... 



55 Cs ... 



56 Ba . . . 



57 La . . . 



58 Ce ... 



59 Pr ... 

 60Nd... 



62 Sm . . . 



63 Eu... 



64 Gd... 



65 Tb... 



66 Dy... 

 68 Sr ... 

 71 Lu... 

 73 Ta ... 

 74W ... 



09.) 



27473 

 289-37 



(fti) 



367-38 



383 60 

 401-41 

 418-73 

 43656 

 454 65 

 491-96 

 510-76 

 53022 

 550-34 

 571-09 

 61191 

 677-07 

 723-30 

 746-45 



251-67 I 251-05 



279-55 

 293-] 9 

 307-26 

 368-58 

 384-31 

 400-23 

 417-25 

 434-80 

 45299 



279-03 

 292-60 

 306-57 



ft 



398-87 

 415-80 

 433-42 

 451-29 



248-76 

 26205 



275-81 

 289-97 

 304-43 



fto 



24940 

 262-73 

 276-48 

 290-69 

 305-20 



490-44 



488-42 



509-78 



507-31 



(ft) 



527-32 



55 



547-63 



614-69 



(ft) 



68363 



680-15 



733-22 



728-65 



758-06 



75350 



367-00 

 382 62 



(ft, fto) 



(fto) 



606-96 

 670-61 

 715-60 

 737 60 



ft-fto 



*l""*2 



062 



043 





0-50 



0-52 



0-57 



0-59 



0-62 



0-69 



0-69 



1-20 



104 





111 



1-36 



1:18 



1-45 



1-26 



1-38 



1-49 



1-70 



1-67 



202 



2-00 



247 



2-23 



2-61 



233 



2-71 



2-52 





2-75 



2-78 



314 



3-48 



3-76 



4-57 



4-37 



4-56 



460 



absorption edge than a line, whereas the line /3 5 , though very 

 faint, for W and Ta is still a very sharp line. 



§ 7. The line fi 7 follows Moseley's law closely. Further- 

 more, the behaviour of this line is what we should expect 

 from theoretical considerations (compare Part V. § 2). For 

 Cd and Ag it could not be separated from the broadening on 

 the short wave-length side of /3 2 , but, since for Ag and espe- 

 cially for Cd this broadening extends to a larger region and 

 is more sharply limited than for the other elements in the 

 neighbourhood, we may assume that /3 7 exists also for these 

 elements. 



§ 8. The lines j3 9 and /3 10 were studied by the author in a 

 former paper*. They are both very faint lines, /3 10 is still 



Zeitschr.f. Physik, vi. p. 185 (1921). 



