xiv.] LITHIUM. 197 



We will now pass to lithium. 



Before the maps comparing the long and short lines of some 

 of the chemical elements with the solar spectrum l were com- 

 municated to the Eoyal Society, I very carefully tested the 

 work of prior observers on the non-coincidence of the red and 

 orange lines of lithium with the Fraunhofer lines, and found 

 that neither of them was strongly, if at all, represented in the 

 sun. This remark also applies to a line in the blue at wave- 

 length 4603. The lithium line in the violet, however, has a 

 strong representative among the Fraunhofer lines. 



Applying, therefore, the previous method of stating the facts, 

 the presence of this line in the sun differentiates it from all the 

 others. 



Feeble 

 spark 



Arc. 



FIG 77. Showing the various intensities of the lines of Lithium under different 



conditions. 



For the differentiation of the red and yellow lines I need 

 only refer to Bunsen's spectral analytical researches, which 

 were translated in the Philosophical Magazine, December, 1875. 

 In plate 4 two spectra of the chloride of lithium are given, 

 one of them showing the red line strong and the yellow one 

 feeble, the other showing merely a trace of the red line, while 

 the intensity of the yellow one is much increased, and a line in 

 the blue is indicated. 



Certain observations of Professors Tyndall and Frankland, to 

 be referred to in the sequel, differentiate this blue line from 



1 Philosophical Transactions, 1873, Plate 9. 



