1836=] 



Miscellanea, 



158 



" Prom the above data, we may now proceed to extract the simple 

 elements of each specimen of ore: 



No. I. No. 2. No. 3 



L Metallic copper, calculated from the 





30.2 



39.5 



69.0 





0.8 



4,5 



12.8 



to. Carbonic acid, less --g-th for hygrome- 











10.S 



13.1 



6.3 



" The carbonic acid being supposed to be wholly combined with cop- 

 per, while the sulphur may be partly united with iron, we may cal- 

 culate the proportions of the carbonates and sulphurets by means of 

 the scale of chemical equivalents, thus : 



No. t No. 2. No. 3. 



o. The carbonic acid will require copper,. . 31.4 38.6 18.3 

 " Now in the first two of these, the copper required so nearly agrees 

 with the calculated weight of metal, I, that the latter may be looked 

 upon as existing here wholly in the form of carbonate, and the suphur 

 as united entirely with iron*. In No. 3, however, we find that the 

 majority of the copper remains; and knowing the nearly total absence 

 of iron in this specimen, we may conclude it to be a mixture of nearly 

 two parts sulphuret, with one of carbonate. 



tl The miner would rest content with the determination of the pure me- 

 tal in the ore, and would have good reason to be satisfied with the 60 per 

 cent, "actual yield" of No. 3, or even with the 30 per cent, of the poorest 

 of the three ores °, but the mineralogist will prefer an exhibition of the 

 component salts of the ores, according to the usual synthetical formula, 

 I may here remark, th&t the water separated (b ) is more than is re- 

 quired to convert the carbonate into a hydrate or ordinary malachite : 

 thus, 



No. i. No. 2. No. a 



p. The copper combined with carbonic acid 



being,.... 30.2 39.5 18.3 



q. Will require water to hydrate it,. ... . . . . 4.2 5.5 2.6 



The excess in b may have been carbonic acid, partially driven off. 



" The chemical composition of the three minerals may therefore bs 

 thus expressed : 



No. (. No. 2, No, 3, 



Hydrated carbonate of copper, ........ 



52-4 



68-5 



31-7 





0- 



0-? 



63-0 







12-4 



o-o 



Oxide of iron, silex,&e 





25- 1 



5-3 







—60 



o-o 





100-0 



100-0 



iOO-O 



* In the second Analysis of No. 2, however, the copper actually recovered, k, so much 

 exceeds this quantity, that it is evident this ore frequently contains sulphuret, or is of 

 very variable quality, 



