20 
DES. J. PLUCKEE AND J. W. HITTOEF ON THE 
elements when Davy’s charcoal light is produced within an atmosphere of hydrogen, 
when introduced into our tubes is nevertheless rapidly decomposed by the discharge, 
and most incompletely recomposed after the discharge has passed. The inside of the 
tubes is instantly blackened, and in the first moment only, along with the spectrum of 
hydrogen, we perceive the groups of carbon-lines seen in the case of olefiant gas. 
55. Finally, Ruhmkorff’s large induction coil was discharged between two electrodes 
of carbon, surrounded by an atmosphere of hydrogen. The four groups a , b, c, and d 
were obtained, constituting the spectrum of vaporized carbon. 
56. In resuming, we are struck by the variety of appearances presented by ignited 
vapour of carbon when submitted to spectral analysis under different conditions. But, 
whatever may be this variety, it is impossible not to admit that all or nearly all of the 
various types of spectra we described are derived from the same source. We may 
distinguish four such types : 1st, the bands, especially seen when the flame of cyanogen 
is fed by air ; 2ndly, the particular distribution of light and shadow near H|3 when the 
flame of olefiant gas is fed by oxygen ; 3rdly, the large fields shaded by transversal dark 
lines ; 4thly, the characteristic groups of bright lines, a, b, c, d, e, f, g, h , which are to 
be ranged into two different sets, a, b , c, d, and e, f, g, h. It is a curious fact that all 
these different types, either fully developed or indicated only, are represented in the 
flame of cyanogen, if fed with oxygen, while in all the other cases we examined there 
are represented either a single type or two types, or even three, — namely, 1, the third 
type alone ; 2, the first type, with the second set of groups ; 3, the third type, with one 
set of groups (a, b , c, d) ; 4, the same type, with the other set ( e , g) ; 5, the second and 
third types, with the first set of groups. There is no doubt that the different types 
correspond to different degrees of temperature, — the temperature being lowest when the 
bands are principally developed, lower in the case of the second set of groups than in 
the case of the first, lower in the case of the shaded large fields than in the case where 
the characteristic groups appear simultaneously. 
In the present state of the question we are not able fully to explain the various 
types of spectra of carbon. It is only proved that all spectra which we referred to 
carbonic vapour do not contain any bright line belonging to another elementary gas. 
Either the well-known spectra of foreign admixed gases, of nitrogen, oxygen, hydrogen, 
for instance, do not appear at all ; or if they do, they may be subtracted from the whole 
apparent spectrum. 
It appears doubtful that the different types depend solely upon temperature. If so, 
the temperature varying in the different parts of the ignited vapour of carbon, different 
types may be seen simultaneously. We shall not now discuss the influence which the 
coexistence of foreign gases might have on the spectra of vapour of carbon, nor may we 
here decide whether or not, in the lower temperature of the flame, a gaseous compound 
of carbon, not being entirely decomposed, exhibits, with the spectrum of the vapour of 
carbon, simultaneously the spectrum of the undecomposed gas. 
In the spectrum of cyanogen, for instance, we got no visible traces of the spectrum 
