The Hart z: 119 



sufficient data, from which, the different mixtures employed in smelt- 

 ing are formed. For the last century the melting of the schlich has been 

 performed in high furnaces (20 feet) ; and the method consists in 

 desulphurating the galena by means of granulated iron, — the ore 



not having undergone any preceding chemical preparation. Such 

 other additions are made to the galena and iron, so as to insure a 

 perfect fusion, calculated after the result of the assay. 



The following is the composition of one of the mixtures or smelting 

 heaps for the schlich. 



38 quintals of Schlich, (ore washed). 



5£ " " Granulated iron. 

 48 " " Scoria. 



2 " " Abstrichs, with a portion of litharge 

 taken from that which is produced during the latter part of a cupel- 

 lation, containing from one half to three fourths loths of silver per 

 quintal. 



Charcoal is the only combustible employed in this operation, for 

 frequent assays have proved that a portion of schlich is invariably 



this 



an 



metal which not observed when charcoal is employed. Three times 

 the quantity of mixture, as given above, (one rost) may be passed in 

 a single furnace per day ; when the furnace is in good order two hun- 

 dred cubic feet of charcoal are consumed in melting one rost, or the 

 above quantity. The metal is drawn off at intervals of from one hour 

 to one and a half according to the energy of the furnace. The pro- 

 duct of this operation is a certain quantity of lead containing silver, and 

 a great deal of matte, (coarse metal, sub sulphurets,) scoria, &c. be- 

 sides a deposit found in the series of canals that form the cheminees. 



The lead is cupelled for silver, giving litharge, abstrichs, &c. 



The working of the mattes comprehends the following series of 

 operations. 



1. The first matte is roasted three or four times; these roastinrrs 

 last three or four weeks, after w r hich they are smelted in a furnace 

 differing from the first in dimensions, and in the manner of charging. 



" ' ^ mixture is thus composed. 



32 quintals of roasted mattes. 



30 " " scoria containing .10 of lead, 



5 " " cnnnllin^ bottoms, ashes containing: litharge, silver 



&r 



3 " " scoria produced by the reducing of the oxide of lead, 

 1 " " granulated iron. 



