300 report— 1879, 



copper and sodium left the spectrum. During the last few minutes of the hlow the 

 mouth of the converter was dull and without flame, the sulphur and oxidisable 

 matter having been burnt out. 



The principal cost of plant will be for the blast. Where sufficient water-power 

 is available, a plant capable of treating 15,000 tons of pyrites annually could be 

 erected at a cost of about 1,500/. Where, however, water-power is not available, 

 steam boilers will be requisite, and the additional cost for plant may be 500/., or 

 perhaps 1,000/. 



With regard to the furnace, it is proposed to make the hearth, or rather crucible, 

 •of siliceous, aluminous, or refractory carbonaceous material. A sufficiently large 

 proportion of siliceous flux in the furnace charge will greatly mitigate the action 

 of the resulting iron protoxide upon the silica of the lining. Aluminous shrunk 

 bricks may answer still better. It might even be found convenient to allow con- 

 siderable corrosion to the lining to take place, if the converting hearth is of such 

 form, and the materials are of such a nature, that it can be readily and economic- 

 ally renewed. 



It may be also advantageous to run the regulus and slag, after the desired con- 

 centration has been effected, directly on to the hearth of a reverberatory furnace, 

 where they can be kept molten by external heat, and where a more perfect 

 separation of the one from the other may be effected. In such a furnace the final 

 oxidation of the rich regulus would probably be most conveniently effected, 

 although it is of course possible to produce metallic copper from the regulus by the 

 transmission of air currents in a specially constructed furnace. 



Not only would antimony, lead, zinc, copper, nickel, silver, and other valuable 

 metals be extracted from the sulphides that contain them, but also from the incom- 

 bustible fluxing materials that are added to the charge, and the extraction of the 

 copper, and silver, and gold will probably be more complete than by any other 

 known process. In countries where cupreous siliceous schists and sandstones 

 abound, the use of these as siliceous fluxes would partially, if not wholly, compen- 

 sate for the loss of copper in the slag. Thus, by using 0*5 ton of such material, 

 containing 05 per cent, of copper for each ton of the sulphuretted ore, the whole 

 of the copper could be recovered from the latter, assuming the slag to contain even 

 as much as 02 per cent, of that metal. 



The crude sulphur may be freed from the accompanying sulphide of arsenic by 

 boiling it with milk of lime, and from the metallic oxides and sulphides with which 

 it is contaminated by distillation ; or purification by bisulphide of carbon might be 

 resorted to. The sulphurous acid can be oxidised in chambers to sulphuric acid, 

 either with or without previous liquefaction. 



This process, on account of its simplicity and economy, may reasonably be 

 expected, not only to take the place of the ordinary smelting, but also of many of 

 the wet processes now in use. 



5. A Lecture Experiment in Illustration of the Hollivay Process of Smelting 

 Sulphide Ores. By Alfred H. Allen, F.C.S. 



By causing oxygen gas to bubble through molten antimony sulphide contained 

 in a V-shaped piece of combustion-tube, combustion takes place with such rise of 

 temperature as to soften the glass, while a sublimate is obtained of antimonious 

 oxide, and sulphurous acid gas is evolved. The sublimate is collected in an empty 

 globe, and the sulphurous acid is absorbed by passing it into a large vessel containing 

 lumps of wood-charcoal. At the conclusion of the experiment the contents of the 

 combustion-tube may be poured out, when a button of metallic antimony free 

 from sulphur is obtained. 



By passing oxygen over lumps of pyrites contained in a heated combustion-tube, 

 vivid combustion takes place, much free sulphur sublimes, and sulphurous acid gas 

 is obtained and absorbed as before described. 



