president's address — SECTION B. 109 



of tlie converter process. Furthermore, lack of manipulative skill 

 then still allowed occasion for the formation of slags rich in copper 

 to arise, and this circumstance, together with the absence of fluedust 

 chambers, &c., for condensing the fumes, was the cause of disparaging 

 balance-sheets. Investigation confirmed the suspicion that, though 

 the loss of silver by volatilisation might be slight in the sUg-making 

 period, it was higher, and possibly very serious, in the after-blows on 

 white metal, and for a number of years a corresponding note of alarm 

 was sounded to the detriment of the process, and is still current in some 

 Cjuarters. As a corrective it was suggested to simply blow the matte 

 up to white metal or regulus, and to run this to blister in the ordinary 

 reverberatory furnace way, or to subject it to the so-called " direct " 

 process, or one of its older or more recent variations. Still more recently 

 the direct electrolysation of the regulus is being urged as the proper 

 means for circumventing heavy losses in silver (and gold). Meanwhile, 

 however, quite cognisant of the fact that the item of losses was the 

 particular feature by virtue of which their marvellous plants might 

 become magnificent mistakes, the large establishments of America 

 and its technical dependencies have continued to blow hundreds of 

 thousands of tons of matte into blister, and have produced millions 

 of ounces of the precious metals, undismayed by the apprehensions 

 that were disquieting more purely academic circles. 



The difficulties in the way of a correct determination of the losses 

 are principally of a practical, i.e., mechanical nature, and reside, in the 

 last instance, in the obstacles which the extremely irregular distribu- 

 tion of the three metals, in all the products involved, opposes to true 

 average samples. An amount of careful sampling of materials very 

 difficult to sample is required, which is calculated to appall the works 

 managers of to-day. Stoppages and clean-ups, i.e., interruptions of 

 current operations, would be necessary which even the strongest metal- 

 lurgical curiosity cannot condone to the disadvantage of the business 

 end of the work, and so the losses in copper-converting have generally 

 been tal-ring care of themselves. As intimated, they have, in a few 

 isolated cases, been crudely determined at large plants with a general 

 result that they might be worse, and no attention is being paid to them 

 in this complacent temper. 



Some of the figures available from the literature of the subject 

 are the following. In the older Anaconda plant (1890-4), on very 

 clean ores, the copper loss appeared to be 4 per cent., and that in silver 

 5 per cent. But this plant had very imperfect dust-catching arrange- 

 ments, and the censurable practice of cc ohng the vessels by filling them 

 with water aggravated the copper loss. In the newer plant (1895) 

 the losses ran out at copper 2 per cent., silver below 1 per cent. This 

 was on a scale of production of 45.000 tons of copper annually. About 

 this time unspeakable losses were attributed to the square-shaped 

 vessels in use at Durango, Colorado, which prejudiced the process 

 considerably. On the best of authority it may be stated that the 

 losses were incurred, but that they were due to the use of linings made 

 of silicious silver ores, carrying lead, which ores, furthermore, were 



