1822.] Variegated Copper Ore, S5 



Klaproth has considered to be oxygen, we may regard this ore 

 as a compound of sulphuret of copper and of sulphuret of iron ; 

 and it v/ould then appear to consist of four atoms of sulphuret 

 of copper and one atom of sulphuret of iron ; thus 



„ /. 1 1 i. r r 64 sulphur 



Four atoms of sulphuret of copper. | ^-^ copper 



n 1 1 . r- r 16 sulphur 



One atom of sulphuret of iron -J 28 iron 



364 

 According to this, its composition will be 



_ ,, By analysis, substituting sul- 



By theory. ^ ph^r for oxygen. 



Sulphur 21-98 21-65 



Copper 70-33 69*50 



Iron 7-69 7-50 



100-00 98-65 



Loss .... 1*35 



100-00 



This is unquestionably a possible, but I think not a probable, 

 combination ; and that the coincidence is accidental is more 

 likely, because the specimen from Rudelstadt contains the same 

 quantity of sulphur, nearly 12 per cent, less of copper, and 

 about 2-i- times more iron. 



According to Mr. Chenevix (Phil. Trans. 1804, p. 60), this 

 ore consists of 



Sulphur 17 to 25 



Copper 65 60 



Iron 13 15 



Too 100 



On these analyses I would remark, that in the first state- 

 ment the sulphur exceeds only by 0*75, the quantity required to 

 convert the copper into sulphuret, without leaving any to com- 

 bine with the iron ; while in the second, the proportions of the 

 constituents are such as to indicate a compound of two atoms of 

 sulphuret of copper and one atom of sulphuret of iron. 



From the differences which exist in the proportions of the 

 constituents of this mineral by the eminent analysts named, I 

 was desirous of submitting the variegated copper to fresh exa- 

 mination : for this purpose I employed a specimen from Ross 

 Island, in the lake of Killarney, which appeared to be remark- 

 ably pure, of a crystalline structure, although not exhibiting 

 a regular crystalline form, and perfectly unmixed with any other 



