106 president's address — SECTION B. 



actual work, have been made ; but a painstaking investigation of 

 concrete cases is still to be looked forward to. Next after Bode's 

 (1872), Hollway's and Professor Akerman's (1878), and Professor 

 Balling's (1882) theoretical calculations of the pyrometric intensity 

 developed by the combustion of the ordinary natural (p}Tites) and 

 metallurgical sulphides (mattes), the first to apply a similar test to the 

 pneumatic treatment of mattes by Bessemerising was the last mentioned. 

 In his text-book of 1885 he calculated the temperature evolved in the 

 blowing of the matte blanche of Eguilles (77.61 per cent, copper) as 1,862°, 

 exclusive of losses by radiation, &c., but accidentally omitted to take 

 into account the calories absorbed in the decomposition of the ferrous- 

 sulphide. No excess of air was assumed to be injected ; but in this 

 respect the tendency has subsequently been to make allowances far 

 exceeding all necessities. Only that particular practice must be con- 

 ceded to represent the type that should be striven for, i.e., the normal 

 one, which utilises for serviceable work as nearly as possible 100 per 

 cent, of the oxygen blown in ; and it is wholly unnecessary, and altogether 

 detrimental, to apply twice the theoretical amount of air, as has been 

 assumed, or even more. 



The most elaborate attempt so far published to elucidate the 

 thermo-chemical mysteries of matte-conversion is that of Jannettaz 

 (1902) (2;). It is, however, after all, only a mere approximation like 

 its predecessors, not executed at the hand of analytical data derived 

 from any one specific case, or series of tests, and therefore goes quite 

 astray. A temperature of as high as 2,009° is calculated for the slag- 

 ing period, which figure is then modified to 1.450° by the introduction 

 of an excess of air based on the practice at Eguilles, where, it is said, 

 2,500 cubic meters of air are blown in for 1,500 kilos of 30 per cent, 

 matte, being one-third more than is required. But even this reduced 

 temperature is too high, for direct measurement, by means of Seger 

 cones encased in iron bottles thrown into the vessel, showed the tempera- 

 ture to be only 1,260°. The heat relations for a blow on regulus are 

 not gone into by this writer, though equally as interesting as those of 

 the slagging period, and at least equally as important, because affording- 

 the proof of the very significant fact that the final temperature in the 

 converter leaves the metallic copper in a sufficiently superheated 

 state to guarantee absolute hquidity. 



This point was incidentally touched upon by Roesing (1892) in 

 a paper (a) devoted to the Bessemerising of argentiferous lead-bullion, 

 in a steel converter, into enriched lead and litharge, an accelerated 

 cupellation process in which the heat relations are rather more favor- 

 able than they are in matte-conversion. For purposes of comparison 

 the above-mentioned Eguilles white metal (77.61 per cent, copper), with 

 an assumed initial temperature of 1,000°, is calculated to a finish at 

 the melting point of copper (1,054°), with 10 per cent, radiation loss,. 

 and the proof is given that an excess of 23 per cent, of air will nullify 

 the process. The same figures, extended and corrected for the actual 



(2) P. Jaimettaz, " Les Convertisseurs pour Cuivre, Paris, 1902." 

 (a) StaM u. Eisen, 1892 ; Eng. and Min. Jl., vol. LIII., 1892. 



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