gio On the Arfeniales of Copper ami of Iron. 



ate of copper, were intimately mixed, and heated at a tow 

 Ted hf.ai, the oxygen feenied to be equally diftributcd through 

 all the lual's^ and eveiy particle leemed perfectly homoge- 

 neous. 



In the ore here fpoken of, it is bv no means rare to find 

 large pieces of real native copper; and, whether we confider 

 it mineralogically or chemically, it certainly is an intereftinl; 

 fubllance. But, how much more will it be efteemed, if it is 

 regarded with a view to public utility ! "• 



The Baron de Born has mentioned a gray cupreous pyrites, 

 which, he fays, contains 90 per cent, ot copper. I have ana- 

 Ivfed a (imilar one from Cornwall, (gray vitreous copper ore, 

 p. 212,) which I found to contain 86 of the fame metal. Biit 

 ifwerefieft, not fo much on the quantity as upon the ex- 

 treme purity of this copper, and the wonderful facility with 

 which this ufeful metal mavbe extra^^ed, it will be found 

 much fiiperior to every copper ore hitherto diicovered. It 

 would be well worth the attention of miners, to keep a con- 

 ftant look-out for this fubftance, which, I am informed, is 

 not rare in Cornwall. It contains no iron, and no fulphur; 

 the abfence of which latter is a peculiar advantage. It is. a 

 fail not generally known, I believe, that there is hardly fuch 

 a thing in commerce, as copper which does not contain a 

 little iulphur ; at lead, I have rarely met with any fuch ; and 

 it requires but a very minute portion of fulphur to inereafe 

 the fufibility of copper. The advantage of obtaining copper 

 free from fulphur, is too obvious to require to be poinicd out ; 

 and that advantage does this ore polleis. 



To work it feparately, if ever it lliould be found in fufficient 

 quantity, would well repay the labour it would coft ; and a 

 very fniall mixture of any difoxidatiug fubltance would, in a 

 Ihort time, reduce immenfe quantities. 



From the loregbing experiments we may perceive into how 

 many errors we niav be drawn, if, in arguing from the refults 

 which we obtain, we pronounce too halHly upon the ftate in 

 which a fubfiance exilts, in the fubje6t of any analylis. After 

 what has been thown, with regard to the aftion of muri.itic 

 acid upon a mixture of metallic copper and black oxide of 

 copper, both reduced to powder, and of the aftion of phof- 

 phorie acid upon the ore itfelf, it may be Hill a doubt whe-- 

 ther thi* ore is really a fuboxide, or a mixture of metallic 

 copper and oxide of copper, at 20 per cent, of oxvgrn. But, 

 as funilar proportions of both, after having been made red- 

 hot, prefented all the properties and appearances of the ore 

 nuich more ftronoly than witen limply mixed, it is fair to 

 conclude that it is a real fuboxide. Had not muriatic acid 



been 



