106 Dr. Attfield on the Spectrum of Carbon. 



state, we shall then have an exception to the law that incandes- 

 cent solids give continuous spectra, of which we have only one 

 other example, viz. the spectrum of bright lines obtained by Bahr 

 and Bunsen from glowing erbia. In the case of erbia it is not 

 impossible that the bright lines are really produced by a gas 

 (Huggins and Reynolds, Proc. Boy. Soc. June 16, 1870) ; and 

 it is by no means improbable that, when a hydrocarbon is burned 

 it is first of all decomposed into its elements, which then com- 

 bine with oxygen. If this be so, the carbon may exist for the 

 moment in the gaseous state." 



The difference to which Professor Piazzi Smyth calls attention 

 between the spectra of compounds and elements (the difference, 

 namely, between PKicker's " spectra of the first order" and 

 " spectra of the second order") is important. It is perfectly 

 true that the spectrum of carbon is a spectrum of the first order, 

 and would, from that evidence, be inferred to be the spectrum of 

 a compound. If, however, this spectrum be caused by a com- 

 pound, it can only be a compound of carbon with carbon. 



XIV. Note on the Spectrum of Carbon. By Dr. Attfield, 

 Professor of Practical Chemistry to the Pharmaceutical Society 

 of Great Britain. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen^ 



IN chemistry, when compounds of an element with dissimilar 

 radicals yield similar reactions with a reagent, the reactions 

 are held to be evidence of the presence of the element, even though 

 that element in its free state be a massive metal and those com- 

 pounds be liquid or even vaporous or gaseous. At least, to 

 the question " who gainsays the deduction ? " the answer is, 

 " at present, no one." 



In 1862 I showed that gaseous or vaporous compounds of car- 

 bon with dissimilar radicals, when ignited by the aid of the chemical 

 force in flames, or by the electric force in tubes, or in certain 

 cases by either force, yielded identical spectra; and therefrom I in- 

 ferred that the spectrum was that of carbon, though I could not 

 say whether the carbon was free or combined in the gases 

 and vapours. And who gainsays the deduction ? Mr. Piazzi 

 Smyth, Astronomer Boyal for Scotland, in the current Number 

 of the Philosophical Magazine (January 1875). 



Mr. Piazzi Smyth regards my deduction as a delusion, a 

 blunder, an egregious error, a myth, a mistake patronized, he 

 says, by the Boyal Society through secret committees, which he 

 designates accursed things, acting occasionally " as very dragons 

 to keep out any salutary doubt expressed on & favoured topic." 



