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



IV. *'Flame Spectra at High Temperatures. Part II. The 

 Spectrum of Metallic Manganese, of Alloys of Manganese, 

 and of Compounds containing that Element." By W. N. 

 HARTLEY, F.R.S. Received April 25, 1894. 



(Abstract.) 



The spectrum of manganese has been the subject of much investi- 

 gation ; the spark spectrum was examined by Huggins, Thalen, and 

 Lecoq de Boisbaudran ; the arc spectrum was studied by Angstrom, 

 Thalen, Cornu, Lockyer, also Liveing and De\var; the flame spectra 

 obtained from compounds of manganese were investigated by Simmler, 

 Von Lichtenfels, Lecoq de Boisbaudran, and Lockyer, while Marshall 

 Watts has given us accurate measurements of the wave-lengths of 

 lines and bands observed in the spark and oxyhydrogen flame-spectra 

 of spiegel-eisen, manganese dioxide, and other compounds of this 

 metal. 



When investigating the spectrum of the Bessemer flame, I found it 

 necessary to compare the spectrum of elementary manganese under 

 different conditions with that of its oxide when heated in the oxy- 

 hydrogen flame. Comparative experiments were made also with 

 various alloys, as spiegel-eisen, silico-spiegel, ferromanganese, tool 

 steel, and malleable nickel which contains manganese; also with 

 compounds containing similar quantities of metal. 



Metallic manganese was prepared by the electrolysis of manganese 

 chloride, from which all other metals had been carefully separated. 

 One preparation of pure manganese oxide was precipitated from a 

 solution of potassium permanganate by the action of alcohol and a 

 small quantity of sulphurous acid. Other specimens were precipitated 

 from solutions of potassium permanganate by the addition of hydrogen 

 peroxide. By this treatment pure manganic oxide containing only 

 traces of potash was obtained. From one preparation even the potas- 

 sium was removed. 



Photographs of the spectra of metallic manganese and of manganic 

 oxide were taken and compared. They were also compared with the 

 spectra of the alloys of manganese. The periods of exposure varied 

 from a mere flash in the case of spiegel-eisen when being poured into 

 a Bessemer converter, to 30 minutes and even as much as 80 minutes 

 with manganic oxide. 



The leading features of the spectra of manganese and manganese 

 oxide are the same, but they differ in detail, as may be observed by 

 comparing the wave-lengths of the lines and bands in their respective 

 spectra, 



