168 Profs. Liveing and Dewar on the Spectral Lines 



Strips of copper, electro-plated with nickel, brought out 

 almost all the strong nickel lines in the ultra-violet between 

 K and Q; 25 were photographed. When nickel oxalate was 

 put in so as to give a powder of metallic nickel after the first 

 explosion, the same lines were developed, and three additional 

 lines in the ultra-violet. Only one line was seen in the 

 visible part of the spectrum, and that was the yellowish-green 

 line (w.l. 5476). 



Copper wires electro-plated with cobalt gave in the flash 

 22 lines in the violet and ultra-violet, between G and P; no 

 lines beyond those limits. Cobalt oxalate gave no more. 



No other metal gave anything like so many lines as iron, 

 nickel, and cobalt ; and it is remarkable that almost all the 

 lines of these metals developed in the flash lie in the same 

 region between G and P. 



We expected that manganese would have given several 

 lines in the flash ; but it was not so. Neither metallic man- 

 ganese, nor any of several compounds which we tried, gave 

 us any lines of that metal except the violet triplet, and this 

 was generally given by the iron tube alone, and was merely 

 stronger for the manganese put in. The green channellings 

 characteristic of manganese, and ascribed to the oxide, were, 

 however, well seen when metallic manganese was used. 



Chromium, introduced as bichromate of ammonia, which of 

 course became chromium oxide at the first flash, gave three 

 triplets in the green, the indigo, and the ultra-violet near JST 

 respectively, but no other lines. 



Bismuth, antimony, and arsenic gave no lines, nor did 

 mercury spread over a sheet of copper lining the tube. 

 Several metals were tried as amalgams spread over such a 

 piece of copper, but with no fresh results, except in the case 

 of thallium, which gave the green line strongly, the strong 

 line between L and M, and two lines between N and 0. 



On the whole it does not appear that the form in which the 

 metal is introduced into the tube makes much difference. 

 The merest traces of those which gave lines were sufficient. 

 Generally when a metal had been put into the tube, its lines 

 continued to show after the strip or lining had been removed. 

 Thus, after the nickel strips had been taken out, and the tubo 

 cleaned out as completely as it could be mechanically, the 

 nickel lines still came out in the flash, and the same was the 

 case with other metals. 



The strongest part of the water-spectrum, from s to near R, 

 generally impressed itself more or less on the photographic 

 plate; but, with the exception of T, which was only developed 

 on co or twice, no lines made their appearance in the region 

 more refrangible than s. 



