president's address — SECTION B. 71 



flux, reducing metallic copper out of its sulphide, while a sodium sul- 

 phate slag would result capable of carrying in solution the non-cuprous 

 oxides. The method, it appears, was not fully worked out, and the 

 idea has found no further entrance into copper, and is not likely to do 

 so, though an analogue is in use for nickel. 



Another out-of-the-way process of rapid oxidation of mattes, but 

 exhibiting more novel mechanical features than chemical ones, which 

 belongs to this period (the late fifties), is that of von Rostaing.()f) 

 Molten matte is poured on a disc of refractory material, which is caused 

 to revolve at a high rate of speed, say 2,000 revolutions a minute. The 

 stream is thus divided into so fine a spray that each rebounding particle, 

 in its passage through the atmosphere, becomes thoroughly oxidised. 

 Tn this way low-grade matte may be deprived of 37 per cent, of its 

 sulphur contents, and the copper tenor correspondingly increased. 

 There is, of course, no simultaneous increase of temperature, for the 

 particles congeal. But the interesting reversal of the usual procedure 

 in the mechanical execution of the pneumatic method, consisting in 

 projecting the substance to be oxidised through the gaseous oxidising 

 agent, instead of the latter through the former, together with the 

 enrichment which the matte receives (and which is a chief feature of 

 pneumatic smelting), may justify the reference. There have been 

 some modern replicas of this general conception, but it is, on the whole, 

 foreign to current tendencies. 



Causes Contrihulinq to Delay in Applicatwn of Bessefner Idea to 

 Copper. — We now return to the time when the first valid attempts 

 were made to transfer the distinctive features of Bessemer' s great 

 invention to the work of copper-smelting in all earnestness, and in a 

 competent, thorough, and dynamically adequate manner. The realisa- 

 tion of this transfer had, so far, transcended the operative ways and 

 means of earlier experimerters and patentees — a scantiness of equip- 

 ment which lead to half measures, falling far short of the actual 

 capabilities of the principle, even in the comparatively narrow sphere 

 of the red metal. Kupelwieser, writing in 1869, {k) briefly explains 

 the absence of headway in the application of the Bessemer process to 

 the production of metals other than iron by saying that it was owing 

 to a variety of causes. Tn part the delay was due to the expense of 

 the special and cost! 3^ apparatus required for experimenting. More 

 prominent still, however, was a serious fear of heavy metal losses. An 

 erroneous sentiment no doubt prevailed at the time in this respect, 

 nurtm'ed by the knowledge that even the slow-going Welsh roasting 

 process yielded excessively rich slags, so that, in all chemical proba- 

 bility, the accelerated pneumatic method would very injuriously 

 aggravate this evil. Lastly, he attributes the manifest hesitation 

 displayed to an apprehension that success would only be achievable 

 along lines of very considerable operative magnitude. This belief 

 sprang from certain experiences with the Bessemer method for iron, 

 in which a contracted scale of working had so far proved quite dis- 



ij) Bull. Soc. d'Encourag., 1S59. 

 {k) Oesterr. Zeitschr. f. B.-u. H., 1868, vol. XVI., No. 50. 



