22 Mr. H. Eamage. Relations of Spectra, Densities, [Kov. 7,. 



Rubidium. 





Second Series. 





First Series. 





m. 







Differ- 







Differ. 





Observed. 



Calculated. 



ences 



Observed. 



Calculated. 



ences 









-27-5. 1 







-27 5. 



1 



2 

 3 

 4 

 5 



*12575 -0 

 112574 -3 

 23714 -4 

 27832 -8 

 29833 -5 

 30958 



12608 -2 



23738 -6 

 27861 «5 

 29860 -6 

 30984 -9 



+ 5 -7 

 + 6'4 

 -3-3 

 + 1-2 ! 

 -0-4 j 

 -0-6 ; 



*12799 -7 

 fl2806-9 

 23791 -4 

 27868 -4 

 29852 -6 

 30968 -4 



12851 9 



23818 -1 

 27897 -3 

 29879-8 

 30996 -2 



+ 24-7 

 + 17 -5 



- 0-8 

 + 1-4 



- 0-3 

 + 0*3 



Caesium. 





Second Series. 



First Series. 



m. 



Observed. 



Calculated. 



Differ- 



Observed. 



Calculated. 



Differ- 









ences. 







ences. 



1 



flll69 -8 



13170-9 



+ 1-1 



fll723-0 



11718 -4 



-4-6 



2 



21764 -8 



21763-1 



-1-7 



21945 -6 



21944 -3 



-1-3 



3 



25707 -9 



25707 -7 



-0-2- 



i 25790 -4 



25790*3 



-0-1 



4 



27635 -7 



27633 -4 



-2-3 



: 27680 -0 



27677 "9 



-2-1 



5 









; 28750 -3 



28749 -3 



-1-0 



6 









! 29417 '3 



29416 -7 



-0-6 



This formula, though empirical, involves only seven adjustable con- 

 stants ; in these tables it represents, in the two series, thirty-two lines- 

 It thus affords striking evidence for the fundamental identity of type- 

 of the spectra of the three metals to which it applies, and indicates that 

 their differences depend on the atomic mass alone. This evidence 

 is further strengthened when it is remembered that, being only an 

 approximation to an unknown formula, it will naturally come nearer 

 it for large values of m than for small ones. Additional evidence 

 supporting these views is given above by the observations upon the- 

 subordinate series of these three metals, in which the differences depend 

 directly on the atomic mass, and upon the fundamental spectra of 

 calcium, strontium, and barium, in which the differences depend on the 

 square of the atomic mass. — Added January 27, 1902.] 



Rydberg's formula and method give better results for the series 



* Kayser and Runge. 



f Lehmann, ' Ann. d. Physik,' vol. 5, p. 633, 1901. Unmarked lines observed 

 by the Author (Flame Spectra) . 



