493 Mr. J. Napier on Copper Smelting. 



at any time more than 0*13 per cent, of antimony, gave by 

 analysis, about two inches from the surface, — 



Copper .... 50-30 



Silica ...... 42-43 



Sulphur .... 2-11 



Iron 1-68 



Tin -16 



Antimony ... 1*92 



98-60 



The relation of the antimony to the copper in this analysis is 

 3*8 per cent., showing the accumulation of that metal, caused 

 no doubt by the strong attraction which silica has for the oxide 

 of antimony ; and suggests the probability of some of the anti- 

 mony existmg in the copper, not as an alloy, but in the form of 

 a compound, probably antimoniate of copper, which the silica of 

 the bottom decomposes. All the impurities found deteriorating 

 copper exist in the ore ; and we repeat what has been previously 

 stated, that if these metals be not removed before the copper 

 reaches the state of metal, their entire separation is as yet com- 

 mercially impracticable. 



The effect of minute quantities of metal in copper has not yet 

 been fully investigated, and a considerable difference of opinion 

 exists on this question. A few years ago a quantity of copper 

 was returned to the makers as unfit for the purposes for which it 

 was sold, being brittle. This on being analysed gave a trace of 

 nickel, which was considered the deteriorating impurity. Expe- 

 riments made by Bun sen on this subject showed that small 

 quantities of nickel do not affect the roUing property of copper. 



Arsenic in copper is considered very deleterious both by 

 smelters and copper-workers. Dr. Percy has shown that the 

 presence of that metal is not hurtful. 



Silver has been found in copper complained of, and con- 

 sequently considered to be the deteriorating agent. We have 

 found copper highly prized by the manufacturers for its quality, 

 containing from 20 to 25 oz. of silver per ton of copper. We 

 have no doubt but all these statements are true ; an alloy in one 

 proportion may deteriorate, and in another improve certain work- 

 ing qualities of copper. A minute quantity of lead does not 

 seem to hurt copper, yet it requires but a small proportion of 

 that metal to make copper brittle. Iron makes copper hard, 

 yet we have seen it with 0*3 per cent, of that metal highly prized 

 both for rolling and hammering. These cases are cited to show 

 how much has yet to be done in this inquiry. 



Tliere is another circumstance connected with the working of 

 copper closely related to the presence of minute quantities of 



