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



The cause of the Non-appearance of Lines at the Commencement and 

 Termination of th,e " Slow." 



Some controversy followed upon the publication of the papers by 

 Roscoe and Lielegg. Tunner stated that in Sweden the Bessemer- 

 process was not facilitated by the use of the spectroscope. Brunner 

 pointed out that the spectroscopic phenomena were not dependent on 

 the combustion of carbon, but were characteristic of the various 

 impurities in the metal. Wedding and Silliman discussed the origin 

 of the spectrum seen at different periods of the "blow," and failed ta 

 account fully at that time for the non-appearance of lines at its com- 

 mencement and termination. Their views did not harmonise. Many 

 facts were discovered which were not understood, appeared contra- 

 dictory, and required verification. These have all been carefully 

 examined and accounted for. 



Support is given to Wedding's view, based on the analyses of 

 Brunner, that the non-appearance of the lines of manganese at the- 

 commencement and termination of the blow is owing to the quantity 

 of metal volatilised at those periods being insufficient for the produc- 

 tion of a spectrum. At the commencement the temperature is too 

 low, being very little above that of the molten metal ; and, as free 

 oxygen escapes along with carbon dioxide, the gaseous mixture con- 

 tains too small a proportion of carbon monoxide. The alkalies which 

 come from the ganister lining of the converter are present as silicates, 

 and in very small proportion ; many silicates, such as, for instance, 

 felspar, do not exhibit spectra of the alkalies they contain until 

 heated in the oxyhydrogen flame, but at this temperature the metals- 

 potassium, lithium, and rubidium have been detected with the 

 greatest ease in such silicates. Similarly, the alkali metals do not 

 show themselves in the Bessemer flame until a layer of slag has been 

 formed, and the temperature has risen sufficiently high for these- 

 basic constituents to be vaporised. At the temperature of the- 

 "boil," or second period, both metallic manganese and iron are freely 

 vaporised in a current of carbon monoxide, which, in a highly 

 heated state, rushes out of the bath of molten metal. The evidence- 

 of this is the large number of bands of manganese and lines of iron 

 in the spectrum. 



When the metal blown contains but little manganese, as, for 

 iustance, haematite pig, this is all converted into silicate during the 

 first period. The manganese spectrum in the flame does not arise- 

 from that substance being contained in the bath of metal, it must be 

 vaporised from the slag. That this is so has been proved by photo- 

 graphs of the spectrum from samples of slag obtained from the Crewe- 

 works. There is very little difference between these and the photo- 

 graphs of the flame-spectrum taken at Crewe, during the " boil," the- 





