26S ANALTSIS of a COPPER ORE, tjc. 



If we compare this analyfis with feveral analyfes of grey cop- 

 per ore, lately publifhed by Klaproth, we mail find, that the 

 conftituents are the fame in both ; but the proportions of the 

 two firft ingredients are very nearly reverfed. Klaproth ob- 

 tained from 0.4 to 0.5 of copper, and from 0.22 to 0.27 of 

 iron. This renders it obvious, that the two ores were not in 

 the fame ftate. I have little doubt, that the difference, how- 

 ever, is merely apparent, and that it arofe, altogether, from a 

 quantity of iron pyrites, and perhaps alfo of arfenic pyrites, 

 which I could not feparate from the grey copper ore which I 

 examined. Both of thefe minerals could be diftinctly feen in 

 many of the fpecimens, intimately mixed with the grey cop- 

 per ; and I have no doubt that the fame mixture exifted, even 

 in thofe fpecimens which were felected as pureft. The differ- 

 ence in the proportions of copper and arfenic, obtained by 

 Klaproth* in his various analyfes, is fo confiderable, as to 

 lead to a fufpicion, that even his fpecimens, in all probability, 

 contained a mixture of foreign matter. 



* Gehlen's Jour. vol. v. p. 9. 11. 13. 



VIII. 



