48 PYROMETALLURGY. [III. 



The ore is now converted into regulus by fusion with lime 

 and old slag, in a metal furnace ; if the proportion of copper 

 is less than 25 per cent., a second roasting of the ore is also 

 advisable, previous to its treatment in the "metal" furnace. 



The regulus is to be mixed with a quantity of sand equalling 

 the amount of contained oxides of copper and iron ; also with 

 sufficient lime and old slag to promote fluxing. Charcoal — 

 say one-tenth of the weight of sand and flux — is also added, 

 and heat applied. After fusion, an additional portion of 

 coal is well stirred in and the heat increased and continued 

 for a short time. By this operation the silicate of copper, at 

 first formed, is reduced, while the silicate of iron remains 

 untouched. 



It is doubtful whether, in working copper-ores, mixed to 

 only 8 per cent., the metal can be extracted by these few 

 operations without loss of copper ; for, in the ordinary process, 

 the sulphur left after roasting serves to collect the metal more 

 perfectly from the slag. 



Phosphorus in Copper. — Percy and James (Ch. Gaz. viii.) 

 have given the results of a series of essays which go to prove 

 that the presence of phosphorus in copper improves its sound- 

 ing quality in casting ; an effect also produced by small pro- 

 portions of arsenic. They found that even as much as 2.4 

 per cent, of phosphorus did not impair the tenacity or mallea- 

 bility of the copper. It seems also to exert a protective 

 influence against the corrosive action of sea-water. 



Coating Iron with Copper. — Pomeroy's patent (Lond. Journ. 

 Oct. 1850) proposes to make sheet-copper similar to sheet- 

 tin, by which a stiff'ness is imparted to the copper, which is 

 desirable in many processes of the arts. After cleansing the 

 surface by acid-water and heat, the sheet-iron is dipped into 

 water containing clay suspended in it, and then dried, when it is 

 plunged for a moment of time into melted copper. The sheet 

 metal may then be rolled. The chemical reason given for the 

 use of a clay bath to protect the iron from oxidation, viz. the 

 ammonia In the clay neutralizing the acid left on the iron 

 from the acid bath, — is erroneous. 



