[ 302 ] 

 XXXIX. Proceedings of Learned Societies, 



ROYAL SOCIETY. 



[Continued from p. 225.] 



June 16, 1870. — General Sir Edward Sabine, K.C.B., President, in 



the Chair. 



HP HE following communication was read : — 



-*- " Note on the Spectra of Erbia and some other Earths." By 

 William Huggins, LL.D., F.R.S. 



Bahr and Bun sen have shown * that erbia, rendered incandescent 

 in a Bunsen's gas-flame, gives a spectrum of bright lines in addition 

 to a brilliant continuous spectrum. As they were unable to discover 

 the bright lines in the flame beyond the limits of the solid erbia, 

 they suggest that the light which is dispersed by the prism into 

 bright lines is emitted by the solid erbia, which substance therefore 

 appears to stand alone, as a remarkable exception, among solid 

 bodies. Bahr and Bunsen found the spectrum of bright lines to 

 coincide very nearly with the absorption spectrum of some com- 

 pounds of erbium. 



A few weeks since, when in Ireland, I made the observation that 

 the spectrum of the ordinary lime-light contains bright linesf. Dr. 

 Emerson Reynolds, Director of the Laboratory of the Royal Dublin 

 Society, kindly undertook to make experiments to ascertain from the 

 position of the lines if they were due to the cylinder of lime, or to im- 

 purities contained in it. 



Upon my return to town I made the following experiments; 

 shortly after commencing them I received from Dr. Reynolds the 

 account of his experiments, which, with his permission, I have added 

 to this note. 



Erbia. — A few months since, I received, through the kindness of 

 Dr. Roscoe, F.R.S., a few grains of nitrate of erbia, which he had 

 procured from a trustworthy source. I followed Bunsen's method 

 of placing it with syrupy phosphoric acid upon a platinum wire. 

 The erbia, obtained by this method in a finely divided state, was 

 then submitted to the heat of the oxyhydrogen blowpipe. 



In all the experiments described in this paper hydrogen alone was 

 first turned on, and the effect of the heat of the flame on the sub- 

 stance under examination observed with the spectroscope. Oxygen 

 was then admitted slowly, and the effect of the increased heat care- 

 fully noted. 



With the flame of hydrogen alone, the lines represented in the 

 map which accompanies Bahr and Bunsen's paper were seen ; but the 



* Liebig's Annalen, Bd. lxi. (1866) S. 1. 



t Dr. W. Allen Miller informs me that in 1845 he noticed a bright line 

 in the spectrum of the diffused light of the oxyhydrogen jet reflected from a sheet 

 of paper. 



