Art. VIII. — The Spectra of the Alkalies and their 

 Atomic Weiyhts. 



By L. RuMMEL. 



[Eead 10th June, 1897]. 



In a paper read before the Royal Society of Victoria in 



V 

 November last \ea\\ I introduced the formula \ = x + —t — , by 



which to express the relationship of several spectrum lines of 

 the same metal. The three constants x, y and s I determined 

 from three successive wave lengths, n being assumed a round 

 number and found experimentally. In order to test the validity 

 of the last assumption and to effect a better accordance between 

 the experimental and the calculated values, I have added a 

 fourth wave length and determined the value of n by an 

 additional equation. If a, b, c and d are the numbers repre- 

 senting the wave lengths of four successive spectrum lines of a 

 series, their relations may be expressed as follows : 

 r 



a = X + 



b = X + 



;r - z 

 r 



XA- 



{n + -If - z 



a = x + 



[n + 'if-z 

 and theii' constants found by the four equations : 



1 ,-_.,^ y 



-'• ;• 



n- — z 

 Xa-b){,r-z)[{u + \f^z] 



•2n + \ 

 3 .^,.._ {b-c)[2H + \){\n + \) 



, ., , o 27a -32/^ 



it a = a - c and /? -= ^ '^ ' 



b - d 



