Crystallized Minerals by Heat. 133 



phuret of copper. If the ore has been too much roasted* 

 there remains too little sulphuret of iron to collect all the cu- 

 preous particles throughout the whole mass of the slags ; and 

 the smelters must add in this case some of the rich ore not 

 roasted. 



The metallic compounds are roasted six times ; and, by 

 this operation they are transformed into a mixture of magne- 

 tic oxide of iron, and oxide of copper. This mass is now- 

 melted either with quartz, or with the quartzy ore, and their 

 result is a silicate of the protoxide of iron and black copper. 

 In the process followed in the Hartz for refining copper} 

 much protoxide of that metal is formed, in the middle of 

 which large crystals of arsenious acid are found, but never, 

 as far as I know, any oxide of antimony. 



The purpose of refining iron is to separate along with the 

 carbon, all those substances which might have a bad in- 

 fluence on the quality of the wrought iron. In this view part 

 of the pig-iron is first oxydised ; the oxide of iron combines 

 with the silica, which either is introduced by the charcoal, or 

 produced by the decomposition of the silica contained in the 

 iron, and forms a silicate. If the quantity of oxide of iron is 

 too great, this oxide again acts upon the melted iron, or it 

 combines with the silicate, and forms a sub-silicate, which 

 being very fusible, will mix entirely with the melted mass, 

 and burn its carbon, because the affinity between the oxide 

 and silica is greater for forming a silicate than an embrolicate, 

 and to discharge the rest of the oxide, when in contact with 

 the carbon at the temperature of the refining furnaces. — 

 {Anil, de Chim. torn xxiv. p. 355 ; Ann. des Mines, torn ix. 

 p. 176.) 



Art. XXII. — Notice respecting Euchroite, a New Mineral 

 Species. By William Haidinger, Esq. F.R. S.E. Com- 

 municated by the Author. 



A mineral has lately been brought to this country under 

 the name of Euchroite, of which a short notice will find here 



