268 ANALYSIS of 4 COPPER ORE, &e. 
If we compare this analyfis with feveral analyfes of grey cop- 
per ore, lately publifhed by Kuarrorn, we fhall find, that the 
conftituents are the fame in both; but the proportions of the 
two firft ingredients are very nearly reverfed. KiaPrroTH 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 diftin@ly 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 
Kxarroru * in his various analyfes, is fo confiderable, as to 
lead to a fufpicion, that even his {pecimens, in all probability, 
contained a mixture of foreign matter. 
® GrHLEn’s Jour, vol. v. p. 9. 21.13. 
VIII. 
