PRESIDENT S ADDRESS — SECTION B. 127 



Under given conditions the rise from 95 per cent, to 96 per cent, 

 of the iron enriches the matte from 40 per cent, to 50 per cent, of 

 copper. 



Pyritic Smelting. — Not all pyritic ores, however, are sufl&ciently 

 low in associated earthy matter, or gangue, to be amenable to the 

 almost cokeless variety of pneumatic treatment. Fortunately, a 

 deficiency in iron and sulphur can be quite made up by a proper addi- 

 tion of carbon? ceous fuel, commonly coke, the three fuels burning 

 conjointly without interference, except, of course, that the carbon 

 arrogates to itself the first allegiance of the oxygen. Barring the 

 introduction of the " pyritic efEc^t," this special work does not very 

 materially differ from the older raw smelting. It will always require 

 the use of an essential proportion of carbonaceous fuel. It may, 

 therefore, be dismissed as a side issue of our subject, because it is only 

 a partial materialisation of our main theme. The conditions of work 

 are quite distinct from those characteristic of true pyrite-smelting, 

 and much more facile. As the latter will always be applicable to a few 

 localities only, it may, however, be stated that the compromise treat- 

 ment of semi-pyritic ores here referred to, or modern " pyritic smelt- 

 ing," is destined to greatly surpass the purer form, or " pyrite-smelt- 

 ing," in general economic importance, as time goes on. Too much 

 stress cannot be laid on its very decided utility, and it is not an over- 

 estimate to say that it will yet be found to be the special channel 

 through which the general mechanical and operative media of blast- 

 furnace smelting, other than iron, will be chiefly improved and further 

 enlarged in the futm-e. The method is bound only to a modicum of 

 copper, but may treat any percentage ; it has in its favor the greatest 

 latitude in point of slag composition, both as to acidity and relative 

 proportions of metallic and earthy bases ; it allows of any concentra- 

 tion ratio whatsoever, dependent on the ore composition, and it permits 

 of enormous tonnages ; also, on profitable grounds, of the reinstate- 

 ment of hot blast. 



Apparatus for Ores. — With regard to the apparatus required for 

 the pneumatic treatment of ores, it need only be remarked that the 

 blast furnaces used follow the general lines of construction character- 

 istic of modern copper-matting furnaces, the most salient special 

 peculiarity, perhaps, being a very large number of tuyeres. Other 

 constructional dtmands, which the fiirnace action would seem to make 

 towards conformable departures from established types, are not yet 

 sufficiently clearly understood to have led to any positive innovations 

 and the fixation of a special design, though, needless to say, there are 

 innumerable inventions and tentative improvements before the pro- 

 fession. The blast paraphernalia calls for no observation, beyond the 

 remark that its capacity should be ample, and that blast pressures are 

 steadily rising, 31bs. per square inch now being merely middling. As 

 in ordinary copper-smelting, rotary blowers continue chiefly to be 

 used, though their place is disputed by piston-blowing engines, while 

 the turbo-blower is the latest rival of both. 



Summary). — We have now followed the development of the rapid 

 oxidation processes, apphed to copper mattes and ores, through to the 



