Si 



Component 

 parts of the 

 scoria: No. 1 



No. 2. 



Assay gaVe 

 of iron. 



The iron 



slightly 



oxiUed. 



SMELTING OP CTJPREOUS PYRITES. 



were treated witti concentrated muriatic acid, mixed with 

 a little nitric acid. With this tliey formed a tolerably te- 

 nacious jelly, which was diluted by adding water, and boil- 

 ing- it. The insoluble part, become very white,, was sepa- 

 rated, dried, weighed, and then heated red hot, to expel the 

 sulphur* The residuum had all the characters of wlex. 

 The muriatic solution contained no sulphuric acid. To 

 this ammonia was added in excess, which gave indications 

 of copper and dissolved the zinc. The precipitated oxide of 

 iron was treated while wet with a solution of caustic potash, 

 to separate the alumine. Into the aramoniacal liquor oxa- 

 late of ammonia was poured, to separate the lime : after 

 which an excesg of sulphuric acid was added, in order to pre- 

 cipitate the co})per by a slip of iron. By a large quantity 

 of ammonia the zinc was separated from the iron intro- 

 duced ; and the proportion of this metal was determined 

 by converting it into a prussiate. 



The first precipitate of oxide of iron was examined anevr, 

 in the hope of finding in it portions of copper and of lime, 

 which might have escaped the first operations. The sul- 

 phur, copper, and zinc, were examined by separate experi- 

 ments. 



From 100 parts of tlie scoriae of the roasted ore were ob- 

 tained silex 31, red oxide of iron 75, metallic zinc 2. Be- 

 side which there were some indications of copper and sul- 

 phur, and an atom of lime. 



From 100 parts of the scoriae of the roasted matt were 

 obtained silex 22, red oxide of iron C)0, lime 3, sulphur 3 ; 

 beside a trace of copper and of zinc. 

 50 The assay in the dry way, with Guy ton's flux, gave 50 

 per cent of iron. 



The iron in these scorife is very little oxided^ for the weight 

 of all the products of the analysis exceeds that of the sub- 

 stance employed, and ammonia precipitates the muriatic 

 solutions of a green colour*; It is observable too, that the 

 second kind of scorife contained much more iron than the first. 



Some 



iBtate of the 'The stats of the iron in this combination appears to me very doubt- 



iron doubtful, fui . for, if we consider it as black oxide, that is with 27 per cent of 

 oxigen, it is not easy to explain the efFcrvesceuce, that the powdered 



scoriir 



