$8 SMELTING OF CUPRKOpS PYIITTES. 



the rich matts, except in quantity sufficient as it were to 



complete tlie saturation of tlie su1])hur. 

 A small q«an- The process adopted at Chessy is as remarkahle for the 

 extiacteTfrom "^^J^^^^ ^^ which it accomplishes its object, as for the sim- 

 a large portion plicity of the agents.it employs. From a ferruj^inous mass 

 of irou. containing only 4 or 5 per cent of copper, more than half 



this is obtained; a result, that theory could scarcely have 



predicted, since it can hardly render it conceivable. ♦ 



Oxide of iron fo ascertain how far oxide of iron is capable of direct 



COIVi billed di- , • • ■ ^ ■^ ^r ^ • • • 



rectiy with si- combmation with silex, Mr. Guemveau intntiately mixed 



*^^* some red oxide with powdered quartz; put the mixture into 



a crucible lined with a thin stratum of levigated quartz; and 



exposed it to a forge fire equal to the heat of the furnace. 



Forms a glass, The first trials produced only glasses njore or less opake 



and coloured ; but at length he formed a compact com- 



,pound of a metallic aspect, exhibiting laminae indicative of 



crystallization, and in Cact perfectly similar to the scori<^. 



The coating of the crucible was attacked, but the crucible 



•was not melted. When the siiex was equal or superior in 



unless the iron wj^jo^jt to the oxide, the product was vitreous ; when it was 



naii\! ^"l^ ^ third, fourth, or sixth of the mass, it was compact and 



metallic. 

 The operation He likewise attempted to produce in a crucible the same 

 smaU way!'^^ effects as took plaqe in tlie furnaces of Chessy. Accord- 

 ingly he mixed ;with great cave some of the rich copper py- 

 rites, as well roasted as possible, with 14 hundredths of its 

 weight of pure silex, .made it into a paste with olive oil, and 

 put it into a crucible not lined. On heating it as in a com- 

 mon assay, a portion of red copper and some grains were 

 obtained. Some matts were distinguishable, but the greater 

 part of the substance covering the copper had precisely the 

 appearance of the scoriae of Chessy. 

 Why does not Perhaps it may be asked why in iron furnaces, where an 

 silex unite with ^^,^ mixed with quartz is frequently smelted, the same com- 



oxide of iron . * i ^^ i • • p i > t- i • 



in iron fur- bmation between the silex and iron is not tormed? Jb or this 

 iiaces ? several causes may be assigned, acting either separately or 



No. 1), are added to the roasted malts ; and the scorix issuing from the 

 furnace during this operation contain three fourths of their weight (ana- 

 lysis No. 2). 



conjointly. 



