Dr. F. H. Thomson's Historical Notes of Capper Smelting. 339 



6. Remeltiug of slags, or fusion of the rich slags obtained from the 

 operations 4, 7, and 8. 



7. Roasting for white metal, or production of white metal of extra 

 quaUty. This operation includes the roasting of the blue metal 

 obtained in process 5. 



8. Eoasting for regulus, or preparation of extra white metal. 



9. Preparation of crude copper by the roasting and fusion of ordinary 

 white metal, regulus, &c. 



10. Refining and toughening of the crude copper, and production of 

 malleable metal. 



It is quite possible that all these different processes may, to a certain 

 extent, be prudent in the reduction of the very poor ores, but certainly not 

 where the per centage of metal ranges from 20-30, or 40 per cent. ; for 

 the deterioration in the quahty of the metal by the admixture of the 

 high class with the poor is more than enough to balance any advantage 

 derivable from the fusible matrix, combined with the latter, and which 

 is necessary for the reduction of the Cuban and rich foreign ores, having 

 comparatively none. Indeed all the ores brought to this country from 

 South Australia, Chili, Peru, and Cuba, range from 40 to 60 per cent., 

 and could easily be reduced by three or four operations at most. By 

 simple calcination and fusion with a proper flux, such as many of those 

 noted by Napier, Mitchell, Philips, and others, a regulus of 70 or 80 

 per cent, could always be obtained. This, disintegrated, calcined, and 

 fused again in a refining furnace with charcoal, would produce a metallic 

 copper of great purity. I have on many occasions got this result by the 

 appUcation of whinstone, even with much lower class ores. 



The great objection to the admixture of the poor class with the rich 

 consists in the combination of sulphur, arsenic, and other deteriorating 

 principles, always present in the former, requiring much and repeated 

 calcinations for their eradication, and lowering the quality of the metallic 

 result, also adding expense to the process. 



Statistics of the Impokts akd Exports. 



Having thus far attempted to trace copper smelting, its early history 

 and present practical results, it may not be amiss to give a slight 

 statistical digest of the quantities raised in England and derived from 

 other countries ; also the quantities exported and imported, wrought 

 and unwrought. In tracing this portion of my subject, I have ab- 

 stracted so much as may be sufficient in a paper of this limit, from Mr. 

 Hunt's valuable Records of the School of Mines, and from Messrs. 

 Philips and Darlington's Records of Mining and Metallurgy, — the best 



