6 Mr. H. Eamage. Relations of Spectra, Densities, [Nov. 7, 



of these contains one line which is very much stronger than any of the 

 other lines. The wave-lengths are : — Calcium 4227, strontium 4607, 

 barium 5536. Eder and Valenta record them also in Bunsen flame 

 spectra of the chlorides of these metals. They attribute the following 

 lines to the metals : — 





Intensity in — 





Bunsen. 



Oxyhydrogen. 



Arc. 



Calcium — 









4227 



10 



10 



lOr 



Strontium — 









5968 



2 







4608 



10 



10 



10 r 



4032 



2 





Ur 



Barium — 









6497 



2 



7 



Gr 



5536 



10 



10 



lOr 



It is very doubtful if- the strontium lines, wave-lengths 5968 and 

 4032, are due to the metal. They should, if metallic lines, appear in 

 both flame and arc spectra. The barium line A. 6497 is probably due 

 to the metal, as also is a line X " 4554 (?)," which Eder and Valenta 

 attribute to the oxide of barium : it is present both in the oxyhydrogen 

 and arc spectra. 



The three lines in question are practically the only lines due to the 

 metals in their Bunsen flame spectra : they are the strongest lines in the 

 oxyhydrogen flame spectra, and they are reversed in the arc spectra. 

 No other line has been observed which resembles them, so we conclude 

 that they correspond to one another : that they are produced by 

 similar motions of the molecules. 



These lines are probably the only representatives of the principal 

 series of these elements. 



Eyclberg also selects these three lines as corresponding to one 

 another. 



There are other lines in the oxyhydrogen spectra of these elements 

 which must be considered. These present difficulties, and it is prob- 

 able that it will be necessary to examine them under the " Zeeman 

 effect," before a final selection can be made. Some of the lines of 

 barium which should correspond to those observed in calcium and 

 strontium will probably be found in the red region of the spectrum. 

 Ten lines have been observed on the less refrangible side of the line 

 A 4227 in the spectrum of calcium ; eleven have been observed in 

 strontium on the less refrangible side of line A 4607, but none have 



