74 president's address — section b. 



described exactly as we now know it. The flame indications which, as- 

 given, point to a great purity of the matte used, are quite correct, and 

 the completion of the slag-forming period, as revealed by a change in 

 the color of the flame, is explicitly referred to, and is interpreted as 

 standing in some relation to the chemical reactions taking place. It 

 is stated that one may absolutely rely on the fact that, if the process 

 is terminated three to five minutes after this particular alteration in 

 the flame takes place, a product of from 72 per cent, to 80 per cent, 

 copper is obtained, but that further blowing leads to a scorification of 

 copper. The process, it is remarked, could be positively and reliably 

 divided into two periods. The first was distinguished by a yellow 

 flame with violet streaks, a violent ebullition, and vigorous projections 

 from the vessel, with a high temperature, maintained by the com- 

 bustion of the iron, so that during this period the matte and slag were 

 in an exceedingly fluid state. The second period differed from the 

 first by a much shorter flame of a " green " color, by an even or uniform 

 noise within the retort, and by a sinking of the temperature. With 

 the second period the slags grew thick and cold, and enclosed particles 

 of enriched matte. Continuation of this period caused a decided falling 

 off of the temperature, a great entanglement of matte, attended by a 

 considerable copper loss, also the formation of accretion'' of black 

 copper, inconveniently adhering to the coohng walls of the retort. 

 It was, therefore, held advisable to interrupt the process soon after the 

 appearance of the " green " flame, and to diminish the body of slag. 

 This was done by bringing the vessel into the horizontal position and 

 skimming off the slag in layers, after allowing it to cool into such, the 

 skimming being repeated three to five times in each blow. Evidently 

 it was done too timorously. On the completion of the entire blow the 

 vessel contents were poured into a cast-iron mould, in which they 

 separated into rich matte and slag. The quantity of the first mentioned 

 varied greatly, from 2 pud to 18 pud (721bs. to 6481bs.). 



With the 18,0001bs. of matte 15 tests were made in all, which were 

 divided into four groups, viz., enrichment to a product of 72 per cent, 

 to 80 per cent, copper ; retreatment of this product into one of 80 per 

 cent, to 95 per cent, copper ; enrichment of the matte with the injection 

 of steam with the air ; finally, the treatment of the enriched matte to 

 black copper in the roaster furnace (Spleissofen). Complete analytical 

 data support the conclusions drawn, but the gases were not analysed. 



It was unfortunate that the blowing of the white metal in the 

 second group gave disastrous results, for to these is to be attributed 

 the non-appreciation of this portion of the process. Only 20 puds 

 (7201bs.) of the rich matte were used. The blowing was done with 

 the two side tuyeres and only three bottom openings. On pouring, 

 2 pud to 3 pud (721bs. to 1081bs.) of 80 per cent, matte were obtained, 

 but the retort was found lined with a coating of scrap copper of 95 per 

 cent, tenor, from -Jin. to l-Jin. thick, which had remained behind. A 

 repetition of the test, with the addition of charcoal, gave no better 

 results ; neither did the partial tilting of the vessel, so that the blast 

 struck over the surface of the bath, improve matters. The conviction 



