1902.] 



some Lines in the Spectrum of Lithium. 



109 



moist lithium carbonate which had been fused into the aluminium cup. 

 The blue line was very weak and nebulous, and it was difficult to 

 obtain measurements of it. The following were obtained from four 

 photographs :— 4603*18, 4603*14, 4602-99 and 4603-97; the mean 

 of these is 4603*15. Better photographs were obtained when a coil 

 of wire was also introduced into the secondary circuit. The line more 

 nearly resembled that obtained when no Leyden jar was used ; the 

 broad reversed line was more clearly defined at- the electrode when 

 negative than when positive. 



An attempt was made to photograph the blue line in the Bunsen 

 flame spectrum, but with an exposure of six hours no trace of it was 

 obtained. 



Other lines in the Spectrum of Lithium, 



The orange line was examined in the arc and flame spectra by eye 

 observations and by photography. The line in the flame spectrum 

 was measured on four plates : — 



Spectrum. Wave-length. 



244 2 6103*84 centre of line. 



244 2 6103 * 85 near tip of line. 



244 4 6103 * 88 rather strong line. 



245 2 6103*84 



245 3 6103*83 



The mean of these, omitting the rather strong line, is 6103-84. None 

 of these lines showed any signs of reversal. 



The wave-length of the bright line in the arc produced by the 

 Gulcher lamp in the open was : — 



Spectrum. Wave-length. 



241° 6103*81 nebulous in middle with sharp points. 



The nebulous part extended from 

 6102*46 to 6104*94. 



242 4 6103*86 



242 5 6103*82 



The mean result is 6103*83. 



The orange line is easily reversed in the arc. The reversed line was 

 photographed and the wave-length measured on two plates, the results 

 being 6103*82 and 6103*84. The reversal was narrow and the wings did 

 not extend very far. The more refrangible wing was slightly broader 

 than the other, and this difference was observed in the photographs 

 and by eye observations. The part of the arc near the negative pole 

 was examined very carefully ; the line was most sharply reversed in 

 that part, but there was no trace of a broad dark line. The orange 

 line, with the exceptions noted, behaved normally. 



o 2 



