110 president's address— section b. 



incorrectly sampled, so that the metal balance was thrown out of order. 

 Before that time, Vivian's, in Swansea, claimed a loss of 2 per cent, in 

 copper in blowing up to white metal, and considered the losses in further 

 blowing the latter prohibitive. In 1894 Dr. Peters (c) save the figures 

 ior the treatment of a small parcel of matte which, on account of 

 2.2 per cent, of bismuth, had caused an unintentional exceptionally 

 ■careful clean-up. They were 2.9 per cent, for copper, 5.6 per cent, 

 for silver, and no appreciable loss in gold. These results he then re- 

 garded as approximately characteristic of average American practice 

 at that time. Later, in 1895, {d) he estimated the loss, with good dust- 

 chamber facilities and not too many volatile metals in the matte, as 

 1 per cent, to 1.5 per cent, of the copper and 2 per cent, to 2.5 per cent, 

 of the silver. The loss in Bessemerising leady mattes, containing 10 

 per cent, to 15 per cent, lead and 40 per cent, copper, he placed at 33 

 per cent, to 50 per cent, of the silver. Dr. James Douglass, in 1895, (e) 

 on the showing of admittedly inconclusive data, mentions losses of 

 3 per cent, in copper. 5 per cent, in silver, and again, 1899, (/) 4.6 per 

 cent, in silver and 8.2 per cent, in gold. Since then, however, appre- 

 hensions have become very much pacified by greater intimacy with 

 the process, and it is the custom nowadays to rest satisfied that, given 

 good condensing arrangements for the fluedust and fumes, the losses 

 are merely nominal. In any case they are held to be much lower than 

 they would be in the only alternative pyro-metallurgical method — that 

 of roasting : a method, too, which, under the spell of two centuries of 

 supreme sway, has itself generally been left quite untroubled by any 

 serious probing for avenues of loss and the special degree of their in- 

 fluence. A modern French view on the subject of the converter losses 

 is that of M. Vuigner, at Eguilles, 1902, who expresses the opinion that 

 copper is mostly lost by volatilisation, never amounts to 2 per cent., 

 and is taken largely if put down at 1 per cent. ; that the silver loss 

 never surpasses 4 per cent., but is frequently over 2 per cent, when lead 

 and antimony are present ; and who considers that perfect dust and 

 fume deposition will guarantee a practically full recovery of all the 

 three metals. 



Undoubtedly the extent of the actual losses depends largely upon 

 the magnitude of the scale of operations, small plants suffering through 

 channels of incomplete apparatus, &c., against which large plants are 

 protected. As an instance may be cited the interesting case of a care- 

 ful, systematic determination by Juon, in 1903, {g) at the antiquated 

 works at Bogoslowsk. in the Ural Mountains, which was made on a very 

 contracted scale : 882 pud (14 tons) of 29 per cent, matte were melted 

 down in a reverberatory furnace, blown to white metal in a small, 

 inefficiently constructed converter, in eight charges, poured, remelted, 

 and then finished in four charges to black copper of 98 per cent. Taking 



(c) Mineral Industry, 1894, vol. III. 



{d) " Modern Copper-smelting," 7th ed., 1895. 



(e) " Recent American Methods, &c.," Cantor Lecture, Jl. Soc. Arts, vol. LXIII. 



(/) " Treatment of Copper Mattes, &c.," Inst. Min. and Met., 1899. 



(g) Oesterr. Zeiisrhr. f. B. u. H., 1903, vol. LI., No. 30. 



