100 
Copper rods were substituted for the carbons of the inclosed lamp. 
The lower rod was hollow. Cyanogen was passed through it into the are 
and globe. The cyanogen bands were strong. The carbon bands at 2 — 
4737 and 72—4382 appeared as bright as in the inclosed are between carbon 
terminals. 
It may be urged that the decomposition of the cyanogen was brought 
about by the presence of Cu, and not by heat alone. If this be true it 
would seem that the metallic impurities ordinarily present in carbon 
would prevent the formation of cyanogen in an are where N was present 
in traces only. 
Many substances besides N appear to affect the spectrum of carbon. 
Sulphur is an instance. When sulphur vapor was forced into the are it 
seemed to tend to equalize the band spectrum, somewhat diminishing the 
intensity of the lines on the side of the bands next the heads and strength- 
ening the weaker lines on the more refrangible side. The bands were 
widened until the ‘‘grating effect’? became continuous in the region of the 
spectrum photographed. S vapor alone, when forced into an are be- 
tween copper poles, gave a faint “grating effect” in the same region. 
Tue EvLectrotytTic NATURE OF THE ELEcTRIC ARC. By ArtrHUR L. FoLEy. 
[Abstract. ] 
The spectra of twelve elements were studied to determine the nature 
of the lines near the carbons and directly between them. The spectrum 
was obtained by removing the core of one or both of the carbons and re- 
placing it by the salt of the metal to be studied. The salts used were 
barium carbonate, sodium nitrate, the chlorides of zinc, calcium, stron- 
tium, postassium and lithium, the sulphates of chromium, cadmium, and 
aluminum and the oxides of rubidium and titanium. 
Six photographs were taken of the spectrum of each element. The 
conditions were as follows: 
No. I, upper carbon plain (containing no metallic salt) and positive, 
salt in lower carbon. 
No. II, upper carbon plain and negative, salt in lower carbon. 
No. III, salt in upper negative carbon, lower carbon plain. 
No. LY, salt in upper positive carbon, lower carbon plain. 
