ME. J. ATTEIELD ON THE SPECTEUM OE CAEBON. 
223 
3 inches long, with platinum wires fused into its sides, and its ends prolonged by glass 
quills having a capillary bore, was filled with pure dry cyanogen, and the greater por- 
tion of this gas then removed by a good air-pump. Another tube was similarly prepared 
with olefiant gas. The platinum wures in these tubes were then so connected with each 
other that the electric discharge from a powerful induction coil could pass through both 
at the same time. On now observing the spectra of these two lights, in the simul- 
taneous manner previously described, the characteristic lines of the hydrocarbon spec- 
trum were found to be rigidly continued in that of the nitrocarbon. Moreover, by the 
same method of simultaneous observation, the spectrum of each of these electric fiames, 
as they may be termed, was compared with the corresponding chemical fiames, that is, 
with the spectra of the oxy hydro- and oxynitro-carbon jets of gas burning in air. The 
characteristic lines were present in every case. Lastly, by similar interobservation, a 
few other lines in the electric spectrum of the hydrocarbon were proved to be due to 
the presence of hydrogen, and several others in the electric spectrum of the nitrocarbon 
to be caused by the presence of nitrogen. 
The electric discharge through cyanogen rapidly causes decomposition. The charac- 
teristic spectrum soon disappears, a black deposit is formed on the sides of the tube, 
and the spectrum of nitrogen alone remains. Olefiant gas is similarly aflected, but not 
to the same extent. The glass tube is much blackened, but the spectrum is constant. 
Bekthelot has, in fact, already shown that olefiant gas is decomposed by the electric 
current, acetylene being at the same time produced. Indeed, as acetylene may, accord- 
ing to Beethelot, be formed from its elements under the influence of the electric dis- 
charge, it is inconceivable that a hydrocarbon gas could be perfectly decomposed in 
such a tube as I have described. 
The spectrum under investigation having then been obtained in one case when only 
carbon and hydrogen were present, and in another when all elements but carbon and 
nitrogen were absent, furnishes, to my mind, sufficient evidence that the spectrum is 
that of carbon. 
But an interesting confirmation of the conclusion just stated is found in the fact, that 
the same spectrum is obtained when no other elements but carbon and oxygen are 
present, and also when carbon and sulphur are the only elements under examination. 
And first with regard to carbon and oxygen. Carbonic oxide burned in air gives a 
flame possessing a continuous spectrum. A mixture of carbonic oxide and oxygen 
burned from a platinum-tipped safety-jet also gives a more or less continuous spectrum, 
but the light of the spectrum has a tendency to group itself in ill-defined ridges. Car- 
bonic oxide, however, ignited by the electric discharge in a semivacuous tube, gives a 
bright sharp spectrum. This spectrum was proved, by the simultaneous method of 
observation, to be that of carbon plus the spectrum of oxygen. With regard to carbon 
and sulphur almost the same remarks may be made. Bisulphide-of-carbon vapour bums 
in air with a bluish flame. Its spectrum is continuous. Mixed with oxygen and burned 
at the safety-jet, its flame still gives a continuous spectrum, though more distinctly 
