94 



Prof. W. X. Hartley and Mr. H. Eamage. 



lime, slags, flue dust, and the finished steel have all been analysed, and 

 their constituent elements have been traced all through the process 

 of manufacture. 



While no indication was obtained of the amount of phosphorus in 

 the metal during the process of " blowing," some insight into the 

 chemistry of the process has been obtained. The greatest interest, 

 however, is attached to the knowledge it has given us of flame spectra 

 under variations of temperature, and of the wide distribution of many 

 of the rarer elements in minute proportions in ores and common 

 minerals.* 



Comparison of Spectra from Open-hearth and Cupola Furnaces. 



Early in 1895, by kind permission of Mr. F. W. Webb, the flame 

 over the hearth of a Siemens' open hearth steel furnace in Crewe 

 works was examined spectroscopically, but no lines of metals except 

 sodium were detected. The continuous spectrum of the light emitted 

 by the walls was very strong, and extended to wave-length 3470. 

 Observations were also made at this time on the spectra of the flame 

 above the charge in a cupola. While the blast was turned on the 

 flame was bluish, and lines of sodium, lithium, and potassium were 

 observed. When the blast was stopped, the flame became smaller and 

 whiter, and the lines of the above elements became stronger ; the 

 ends of the two strongest bands of manganese were also seen. 



Description of the " Blow" anal 11 Over Blow" in the Basic Bessemer 



Process. 



The converter is first charged with about two tons of lime in lumps, 

 and then with twelve tons of fluid " mixer metal," a mixture of metal 

 coming direct from the blast furnace, and molten pig iron from the 

 cupolas. The blast is turned on and the vessel rotated into a nearly 

 vertical position. 



The "blow" may be divided into three stages. The first stage ends 

 when the flame drops, indicating that the carbon has been burnt. The 

 second stage ends when the vessel is turned down for a sample of 

 metal to be taken out and the slag poured off. More lime is then 

 added and the blow is continued for a few seconds longer to complete 

 the removal of the phosphorus; this forms the third stage. The 

 average duration of the first stage was twelve minutes and twenty 

 seconds, and of the second stage, five and a half minutes. 



The blow began with the expulsion of a large quantity of lime 

 dust, which hid everything from view for a minute or two and covered 



* 'Roy. Soe. Proc.,' toI. 60, pp. 35 and 393; 'Chem. Sec. Trans.,' 1897, pp. 533 

 and 547. 



