268 



Scientific Proceedings, Royal Dublin Society. 



Lithium. 



Lithium chloride gives a beautiful spectrum without difficulty, the 

 luminosity in the tube being of a bright red colour, and a good supply of 

 vapour was easily maintained by the occasional a^lioation of a Meker 

 burner. The metal did not readily give the spectrum of lithium, as it is not 

 sufficiently volatile at the temperature of tlie Meker burner. Tlie red glow 

 of the lithium was seen in the bulb, but it did not extend to the capillary 

 tube, and the photograph only showed one line of lithium, A 4972*1, the 

 other lines being due to more volatile impurities in the metallic lithium used, 

 and were the lines of hydrogen and sodium, together with helium, X 4026'3 ; 

 magnesium, A 2852-2 ; mercury, A 2536-7 ; and manganese, A 2801"3, 

 A 2797-8, and A 2795-3. These are, no doubt, the ultimate lines of these 

 impurities, ; but, if so, it is very remarkable that they are not the strongest 

 lines, and that the lines of manganese are not the ultimate lines of the spark 

 spectrum of that element, and it is certainly strange that, out of the whole 

 spectrum of manganese, only three inconspicuous lines should show. Tlie 

 spectrum of metallic lithium sparked in air is reproduced on the plate for 

 comparison with the vacuum tube spectra of the chloride. 



Principal Lines of Litldum. 



