194 Prof. W. N. Hartley. [June 14, 



Lichtenfels,* Spear Parker,f Kupelwieser,;}: Brunner, and Wedding 

 in 1868 ;|| also by A. Greiner in 1874.^ 



Up to the present time the precise nature of the spectrum, the 

 cause of its production, its sudden disappearance when decarbarization 

 of the metal takes place, and the connexion between the decarburiza- 

 tion of the metal and the extinction of the spectrum, have not been 

 satisfactorily explained. According to Roscoe, Lielegg, Kupelwieser, 

 and Spear Parker, the spectrum is characterised by bands of carbon 

 or of carbon monoxide, which disappear when all carbon is burnt out 

 of the metal. 



On the other hand, according to the investigations of Simmler,** 

 Brunner, Von Lichtenfels, and Wedding, the spectrum is not due to 

 carbon (Roscoe) or to carbon monoxide (Lielegg and Kupelwieser), 

 but to manganese and other elements in the pig-iron. 



The very careful examination of these spectra by Watts and his 

 comparison of them with that of the Bessemer flame led to the con- 

 clusion that it was not the spectrum of carbon in any form nor of 

 manganese, but that of manganic oxide. Lielegg established the fact 

 that carbon monoxide yields a continuous spectrum, and that this gas 

 causes the continuous bright spectrum of the Bessemer flame ; but 

 he also attributed certain lines or bands to the high temperature of the 

 carbon monoxide. All observers are agreed as to the appearance after 

 a certain interval of the lines of the alkali metals which were origin- 

 ally discovered by Roscoe to be present during the first period of the 

 " blow." Watts observed the C line of hydrogen during wet weather. 



This research was undertaken in 1882, and an instrument was 

 devised for the purpose of photographing the spectra of various 

 flames emitted during metallurgical operations. The work was left 

 in abeyance until certain practical difficulties encountered in study- 

 ing flame spectra at high temperatures in the laboratory had been 

 overcome. The original mounting of the instrument was too light, 

 but that which has recently been used with success is described. 



Owing to the courtesy of Mr. F. W. Webb, the engineer of the 

 Locomotive Department of the London and North Western Railway, 

 and of Mr. E. P. Martin, the manager of the Dowlais Ironworks, 

 observations have been made at Crewe and at Dowlais during the past 

 year. About ninety spectra were photographed, about fifty of which 

 were available for study. 



* ' Dingler's Polytech. J.,' vol. 191, p. 213. 

 f ' Chem. News,' vol. 23, p. 25. 



I ' Oesterreichische Zeitschr. fur Berg- und Hiitten-Wesen,' No. 8, p. 59, 1868. 

 Loc. cit., No. 29, p. 227, 1868. 



|| ' Zeitschrift fur das Berg- Hiitten- und Salinen-Wesen,' vol. 27, p. 117, 1869. 

 T ' Revue TJniverselle,' rol. 35, p. 623. 

 ** ' Zeitschr. fur Analytische Chemie,' 1862. 



