Further Observations of Enhanced Lines. 



441 



interior, so that as the carbon burnt away in the arc the calcium in 

 the interior became manifest. 



" Again, we found that when we used a perforated pole and passed 

 a stream of hydrogen into the arc through it, H and K could be 

 both entirely obliterated ; but by then reducing the current of gas 

 they gradually reappeared, and H always came out first; and after- 

 wards K ; and H remained stronger than K, until they had both 

 resumed their ordinary appearance. This observation was repeated 

 several times. 



" Both sets of observations, those with the purified carbon poles 

 and those with the perforated pole, seem to me to confirm your con- 

 clusions. 



" In the case of those with the perforated pole, the stream of 

 hydrogen diluted the calcium vapour, and the degree of dilution was 

 controlled by the rate at which the gas was introduced. The mass 

 of gas passing was too small to reduce the temperature by any 

 considerable amount, or even, I should think, to any sensible 

 amount. 



" We found also that metallic lithium, introduced into the arc, 

 produced effects similar to those produced by hydrogen, that is, that 

 it reduced very much the strength of the H and K lines. If more 

 than a very minute piece of lithium were introduced, the arc was 

 invariably broken, so that we did not notice the complete oblitera- 

 tion of H and K with the Jithium. 



" The reduction of the strength of H and K, in this case, I 

 attribute to the dilution of the calcium vapour by that of lithium." 

 — June 25.] 



" Further Observations of Enhanced Lines.' 5 By J= NORMAN 

 Lockyer, C.B., F.R.S. Beceived May 12,— Read June 17, 

 1897. 



In a recent paper I gave an account of a series of experiments 

 having for their object the determination of the lines which were 

 enhanced in the spectra of iron, magnesium, and calcium, on passing 

 from the arc to a high temperature spark, and I pointed out the 

 presence of these lines in the spectra of the hotter stars and in the 

 solar chromosphere. 



The spectra of the following additional elements have since been 

 investigated in a similar manner, and the enhanced lines have been 

 tabulated and compared with chromospheric and stellar spectra. 



2 i 2 



