SMELTING OF CUPREOUS PYRITES. 55 



after exposure to a red licat, O.Ql gr. As the ammoniacal 

 solution of , copper and zinc had a very slight blue colour, it 

 did not appear necessary, to separate the few atoms of cop- 

 per: so the whole was precipitated together by carbonate of ^^PP®*" ^"'^ 

 r • '^'^ • I r ^^ ^ . ^ Zinc by carbon- 



potash, assisted by a boiling heat. The carbonate, being ate of potash, 

 calcined, gave O'l? gr. of zinc mixed with a very small 

 quantity of copper. The quantity of copper and zinc was 

 ascertained likewise by separating them from the iron by 

 sulphuretted hiilrogen, and it did not differ perceptibly from 

 this. 



One hundred parts of these scoriae gave therefore silex 35, Component 

 barvtes, not sulphurated, 12, alumine 4, lime 3, magnesia 2, parts^ot" scoriae 

 red oxide of iron 46, oxide of zinc 3, beside some traces of 

 copper and of sulphur. 



This specimen contained much less iron than No. 1, which Less iron than 

 was formed under the same circumstances: but the differ- No. 1. 

 ence will not appear surprising to those, who know how 

 much tlie proportions of the gangue, and foreign matter 

 added to the ore, vary in different smeltings. The follow- 

 ing are the most important consequences deducible from 

 these analyses. 



1. The predominant parts of the scoriae of the pyrltous General infer- 

 copper of Chessy are oxide of iron and silex, the rest being ences. 

 variable, and in small proportion. 



2. The combination of the silex with the oxide of iron is 

 effected in the furnaces in which the ore is smelted. 



3. The presence of barytes, not sulphurated, announces, 

 tfiat the sulphate of barytes, which made part of the gangue, 

 is decomposed. No doubt it had been converted into a sul- 

 phuret, the sulphur of which was taken up by the iron or 

 copperj and the free barytes remained in the scoriae. 



4. The scoria? arising from the smelting of the copper py- 

 rites and matts may be considered as iron ores, since they 

 yield a considerable quantity of iron when assayed. 



The application of chemistry to the art of treating ores, chemistr}' the 

 observes Mr. (jueniveau, is considered by all metallurgists means of ex- 

 as one of the most certain means of elucidating its opera- f ^^icaf urol^ ' 

 tions, and consetpiently improving its processes: and ac- cesses, 

 cordingly he relates in a few words the principal parts of 

 tlie metallurgic treatment of the pyritous copper of Chessy, 



from 



