Section III, 1918 



[59] 



Trans. R.S.C. 



Regtilarities in the Spectra of Lead and Tin. 



By R. V. ZuMSTEiN, M.A. 



University of Toronto. 



Presented by Professor E. F. Burton, Ph.D., F.R.S.C. 



(Read May Meeting, 1918). 



Lead and tin belong to a group in Mendeleeff's table in which 

 series of spectral lines have not been recognised. 



Kayser and Runge,^ who made the first exact measurements on 

 the lead arc, pointed out that a group of. ten lines repeated itself 

 three times in the spectrum with constant frequency difference. 

 They will be denoted as Kayser and Runge's I, II, and III groups. 

 The frequency differences are 1081-08, and 2832-0. Seven additional 

 lines have recently been added to these groups by Saunders.^ 



On carefully examining the work of Kayser and Runge, and some 

 unpublished researches of Fuller and Ainslie of this laboratory, it was 

 found that a symmetrical group of three lines repeated itself five times 

 in the spectrum. This gives five groups with constant frequency 

 difference. 



Table I. 



Spectrum of Lead. 



The frequency difference between: 



I and II is 1081-2. 



II and III is 2504-5. 



III and IV is 327-3. 



IV and Vis 8147-1. 



1 H. Kayser, Handb. der Spect., p. 574 (1902). 



2 F. A. Saunders, Ast. Journal, 43, p. 240 (1916). 



