20 Mr. H. Kamage. Relations of Spectra, Densities, [Xov. 7,. 





Differences in Oscillation Frequencies, P t — P 2 . 



111. 





















Sodium. 



Potassium. 



Rubidium. 



Caesium. 



1 



17 



57 



225 



564 



2 



5 



19 



77 



181 



3 





8 



35 



80 



4 





5 



20 



40 



5 





2 







6 











7 











These figures show that the two series merge into one in both sodium 

 and potassium, and that in rubidium and caesium they are rapidly 

 approaching each other. When m = oo, therefore, they must have the- 

 same value, and n^, corresponding to this, must be common to the' 

 two series. 



When we take this view it is pretty evident that the value of fi 

 must vary throughout the series. It diminishes as the refrangibility 

 of the line decreases, and, at the same time, the intensity of the line- 

 increases. 



The differences between the values of \i for the corresponding lines 

 of the two series of each element are very nearly constant. The figures- 

 are as follows : — ■ 



m. 



Differences between values of . 



Series P x — Series P-. 













Potassium. 



Rubidium. 





Caesium. 



1 



-0029 



-0122 ? 





-033] ? 



2 



0-0030 



-0129 





-0321 



3 



-0029 



-0130 





-0320 



4 



-0033 



-0132 





0-0317 



5 



0-0022 









The mean values of these are proportional to the squares of the- 

 atomic masses, and are given by the term 18W 2 x 10~ 7 . 



The diagrams prove that there is a very close relation between the 

 spectra of the three elements under consideration and the atomic 

 masses. Eydberg's equation has, therefore, been modified in accord- 

 ance with the above work, and an empirical formula has been obtained, 

 which contains only one variable, W the atomic mass. One equation, 

 the following, gives the second principal series of all three metals- 

 with considerable accuracy : — 



