332 Tlie Philosophical Society of Glasgotv. 



copper to be extracted during the process, and whose other elements 

 pass into the slags, or are dissipated in the gaseous state. 



3. The water and carbonic acid, which are volatilized by the iirst con- 

 tact of heat either in the calcination or melting. 



In speaking of the Welsh ores, Mr. Mitchell judges correctly; for by 

 no quick or patent process can poor ores be treated alone, with a speedy 

 result, unless by the addition of rich ores. And as the importation of 

 the high class reguline and carbonate ores only began twenty years 

 anterior to 1S4S, it is of the former class he principally writes. 



Certain modifications are now inculcated, to meet the rich additions 

 made to the smelter's heap by the importations from Australia and the 

 western coast of Africa, South Ajnerica, Cuba, &c., but it is merely for 

 the purpose of getting a better quality of copper, as the operations, in- 

 stead of being lessened, are increased to 10. 



1. Calcination of the ores — calcination of sulphuretted ores and 

 medium per centage, with pyritous gangue. 



2. Melting for coarse metal — melting of poor ores crude and 

 roasted. 



3. Calcination of coarse metal. 



4. Melting for white metal — fusion of calcined coarse metal with 

 rich ores. 



5. Melting for blue metal — ^melting of calcined coarse metal with the 

 calcined ores of medium richness. 



6. Smelting of slags — fusion of slags, from operations 4, 7, and 8. 



7. Boasting of white metal — manufacture of extra white metal, or 

 roasting of blue metal. No. 5. 



8. Hoasting for regulus — roasting of extra white metal. 



9. Boasting manufacture of black copper, or roasting of ordinary 

 white metal and regulus. 



10. Befining or toughening. 



The ores noio treated in Wales may be classed into two grand divi- 

 sions. The first composing the product of all the Cornish, Devon, and 

 Irish mines ; the second, those imported from abroad, — the native fur- 

 nishing the poor, and the foreign the rich. The sales in Cornwall 

 include the former — those in Swansea, the latter. 



This gradual increase in the proportion of high-class ores imported, 

 and the heavy smelting chai-ges, now led practical and theoretical men 

 to the train of thought, that a shorter process might be instituted for 

 the purpose of a more speedy unadulterated reduction, and with less 

 expense ; for the charges upon ten consecutive calcinations and fusions 

 were of course very heavy. 



Patent after patent was now ushered into existence — one more 



