338 



Mr. J. N. Lockyer. 



[Apr. 29; 



the oxyhydrocarbon and oxynitrocarbon jets of gas burning in air. 

 The characteristic lines were present in every case. Lastly, by similar 

 inter-observation 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 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. Carbonic oxide, however, 

 ignited by the electric discharge in a semi- vacuous 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 burns 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 furrowed than in the case of carbonic oxide ; but when 

 ignited by the electric current its spectrum is well defined, and is 

 that of carbon plus the sulphur. That is to say, it is the spectrum of 

 carbon plus the spectrum that is obtained from vapour of sulphur 

 when ignited by the electric discharge in an otherwise vacuous tube. 



" Having thus demonstrated that dissimilar compounds containing 

 carbon emit, when sufficiently ignited, similar rays of light, I come to 

 the cod elusion that those rays are characteristic of ignited carbon 

 vapour, and that the phenomenon they give rise to on being refracted 

 by a prism is the spectrum of carbon." 



The only reference to this admirable work, in which vacuum tubes 

 and the electric discharge were largely employed, which I can find in 

 Messrs. Dewar and Liveing's paper is the following : — " The spectrum 

 of hydrocarbon burning in air* has been . . . described .... by 

 Attfield." 



In 1865 Morren wrote : f — 



" A la reception de cet interessant et substantiel Memoire, j'avoue 

 * The italics are mine. — J. N. L. 



f " Annales de Chemie et de Physique," 4 serie, tome iv, pp. 309, 312. 



