PRESIDENT S ADDRESS — SECTION B. 91 



distribution of the precious metals is more imifoim. The direct casting, 

 of the blister from the vessel into thin anode plates, in preparatiou 

 for subsequent electrolytic refining, is also practised, but offers many 

 difficulties. The best solution appears to be to transfer the copper 

 in crane-carried ladles to a special storage reverberatorv furnace, in 

 which it is partially refined and brought to pitch by means of com- 

 pressed air and poling, and from which it is then poured by suspended 

 ladle into a special endless chain casting-machine. 



In point of blast-supply the earlier period simply duplicated the 

 blowing machinery of the steel plants, on a smaller scale, and for a 

 lower pressure. Later on various high-class types of horizontal blowing 

 engines came in, until to-day the practice in respect of this most impor- 

 tant, or rather, vital accessory, stands on the high level of mechanical 

 perfection characteristic of the times. A common deliver}' for the- 

 older, smaller, upright vessels is 3,000 cubic feet of free air per minute. 

 Large units recently installed supply 6,500 to 15,000 cubic feet per 

 minute. The quantity of air consumed may be inferred from the fact 

 that in American practice a 7ft, by I'L^ft. upright vessel demands 

 200.000 cubic feet of free air per short ton of copper produced, not 

 excluding lealcage in transmission, kc. At Mount I-yell the correspond- 

 ing figures are 100,000 cubic feefc for a 50 per cent., and 165,000 cubic 

 feet for a 40 per cent, matte for the long ton of copper. The very- 

 latest blowing apparatus of all, the turbo-blower, of which great things 

 are expected in the future for blast-furnace work, has so far only found 

 one application for copper-converting purposes, and that is at Mount 

 Morgan. Tt is electric motor-driven there, but in combination with 

 the steam turbine — its naturally cognate driving apparatus — its further 

 development may be watched with interest. On purely mechanical 

 grounds, however, no type of rotary blower can ever surpass the 

 efficiency of the reciprocating piston type of blowing-engine. 



The Horizontal Vessel.— In recent years the newer installations- 

 have, as already remarked, been giving the preference of type of vessel 

 to the recumbent horizontal form of Manhes and David, of 1883 : 

 known also as the " trough," " bjrrel," or " Lediorn " converter. 

 They have, however, as also stated, departed very essentially both 

 from the dimensions and detail appointments of the small vessels of 

 Eguilles and their local modifications. As mentioned above, this, 

 shape has a precursor in a form of steel converter constructed by 

 Nystrom, in 1862, the special object of which was to permit the tuyeres 

 to be placed at any desired depth below the surface of the metal, so 

 that the latter could be partially or wholly traversed by the air currents. 

 An advantage, it is stated, did not accrue from this point; on the con- 

 trary, the varying contact of the metal surface and the lining greatly 

 increased the wear of the latter. Turning to copper- converting, it may 

 be said that, as far a-< actual practice is concerned, the same feature, 

 i.e., the ability to regulate the position of the tuyeres to suit the volume 

 of the matte, largely remains a mere mechanical hyperbole. It is 

 contended that a lower pressure of blast, accompanied by a saving in 

 power, &o., is thus rendered sufficient for the oxidation of the matte 



