SMELTING OF CUPRF.OUS PYRITES. ^g 



conjointly. In the first place no doubt the high temperature Owing to the 

 of these furnaces, and the long time the ore is kept in them, ^^f^^^ lengtrof 

 must be reckoned*; neither must we omit the presence of the operation, 

 earths and metallic oxides, the action of which on the silex ^^ ^j^ij^^ g^j,, 

 may counterbalance that of the oxide of iron. To confirm stances, 

 this opinion, Mr. Gueniveau took an artificial compound of 

 ^ilex and iron, added ^ its weight of very pure white marble, 

 made the mixture into a paste with olive oil, and placed it 

 in a crucible lined with charcoal powder. A button of iron 

 and a few grains were obtained ; and the scoriae wore an 

 opake glass, of a light green colour, that did not contain a j. . . 

 fifth of the iron. An analysis of the scoriae of the high fur- mine,' and 

 nace shows, that the separation of the iron is much more "^^'ig^nese, 

 ix UT /• i-ii- promote tiie 



complete, when lime, alumme, and oxidp ol manganese, are separation of 



found in due proportion with the silex. ^^^^ ^^^^^• 



The presence of other earths beside silex, which is advan- These earths, 



tageous in iron furnaces, because they facilitate the reduc- f^ ^Q.^e^case"^ 



tion of this metal, is for the same reason prejudicial in prejudicial ia 



furnaces for smelting cupreous pyrites. In these furnaces '' ^^ °^ ^'^^' 



opposite eiferts are endeavoured to be produced on the iron : 



the object being to reduce the oxide of the metal in the for- 



juer ; while in the latter it is to prevent this reduction, and 



at the same time to promote tlie reduction of the copper. 



The means employed by the metallurgist to eff'ect these 



opposite purpo:^es merit the attention of the man of science. 



The scoriae produced in the smelting works of copper py- The scorix 



rites resemble iron ores, not only in their aspect and mai^- i^("*«"yic'i "i 



, f. -T ' -I 1-11 • 1 i" n-onthanmanr 



netic properties, but m the laciiity witli which they yield a iron ores. 



very considerable quantity of ii'on when assayed. It may 

 be reckoned, that the mean produce of the assay would be 

 at least 40 per cent ; a quantity superior to that of many 

 bog iron ores, which are notwithstanding wrought with ad- 

 vantage. 



To ascertain how far these scoriae are capable of being Examined 



wrouglit for iron in the high furnace, thev were treated with ^'^^^ '^ ^'^^^ *^ 

 , c 1 CI- 1 " 1, • 1 , working them. 



25 per cent ot carbonate ot lime, and a well united button 



was obtained, equivalent to two thirds of the iron it con- 

 tained. 



* This is an opiHioii long held by Mr. Hasscnfratz, 



Mr 



