480 



Prof. A. Smithells on the 



hydrocarbon at a high temperature is the formation of carbon 

 monoxide. 



The fact that carbon monoxide is formed, and formed in 

 the primary chemical act of combustion wherever the Swan 

 spectrum is seen in a hydrocarbon flame, led me to consider 

 whether or not the spectrum was essentially connected with 

 carbon monoxide. 



Our knowledge of the genesis of spectra does not allow 

 us to solve such a question by reasoning alone. But it is 

 no new thing to attribute the spectra of combustion to the 

 products of chemical action. During chemical combination 

 the energy which is transformed can hardly be supposed to 

 exist otherwise than in the vibrations of the nascent substance, 

 rapidly though these vibrations may die down in consequence 

 of radiation and molecular collisions. Thus the spectrum of 

 a hydrogen flame is said to be the spectrum of water, and no 

 luminous radiation from the flame can be recognized as 

 belonging to either the hydrogen or oxygen singly. It seemed 

 therefore prima facie that a spectrum seen in flames only in 

 those regions where carbon monoxide was being formed might 

 depend on the mutual action of carbon and oxygen — in other 

 words, be essentially connected with the carbon monoxide 

 molecule. 



The Sivan Spectrum and the Cyanogen Flame. 



The flame of cyanogen has played an important part in 

 investigations concerning the spectra of carbon compounds. 

 The existence of bands of the Swan spectrum in the brilliant 

 spectrum of cyanogen was pointed out by Attfield (Phil. 

 Trans, clii. p. 221, 1862), and has been the subject of discussion 

 by many observers. When cyanogen is burned in air the 

 green series only of the Swan spectrum is distinctly visible, 

 but in oxygen the Swan spectrum is completely and brilliantly 

 developed. 



The cyanogen flame consists, as is well known, of two dis- 

 tinct parts, a rose-coloured inner zone and a bright-blue 

 outer one. I found that this flame, when produced in the 

 flame-cone separating apparatus, permitted of the ready 

 separation of the two characteristic zones, and in a paper 

 published in conjunction with Dr. Dent (Journ. Chem. Soc. 

 lxv. p. 603, 1894) I gave an account of an investigation of the 

 interconal gases. The analysis showed that the chemical 

 change taking place in the inner cone was essentially the 

 formation of carbon monoxide, this gas afterwards burning 

 in the blue region of the flame to form carbon dioxide. 



