1 22 The llartz. 



During this time twenty three mixtures, composed as above, were 

 smelted, producing two hundred and sixty six quintals of lead, 

 containing silver (Plomb d'oeuvre) and one hundred and sixty nine 

 quintals of mattes. Consumption, six hundred and ten balgen of 

 coke. 



The schlich has been heretofore smelted in high furnaces, with 

 charcoal, and iron employed as the only agent of reduction. Coke 

 is not used. The pores of this combustible lodge a portion of the 

 ore, thus preventing the action of the reducing agent, and proportion- 

 ally increasing the quantity of metal in the scoria. 



Essays have been undertaken with the intention of substituting the 

 methods so advantageously employed in the treatment of the mattes, 

 thus replacing the granulated iron by limestone in the fusion of the 

 ore. These attempts were not as successful as the former. The 

 fusion was unequal, and the scoria rich in lead, apparently owing to 

 the infusibility of the sulphuret of calcium. 



Mr. Ethropel, sub director of the silver works, thought that the 

 lime could have no action upon the galena, and that in the course of 

 smelting the mattes, the lime only acted upon the sulphuret of lead 

 through the intermedium of sulphuret of iron, or the iron liberated 

 by the presence of lime, acts upon the galena. Mr. Albert on the 

 contrary justly held, that lime had a direct action upon sulphuret of 

 lead as already proved both by the experiments of Mr. Berthier and 

 also by the assays differing in the proportions of limestone and iron 

 employed ; two distinct assays were made with limestone alone, the 

 results of which prove the fact beyond a doubt. 



To throw aside any causes of error that might arise from the fine- 

 ness of the schlich and porosity of the coke, the graupen alone 

 was employed ; graupen signifies small pieces of ore obtained by an 

 instrument now very much used in the Hartz, termed setzfass. This 

 instrument is filled with small pieces of ore and gangue and is thus 

 agitated in water by any mechanical power. The gangue or lighter 

 pieces remain at the surface. The graupen or rich ore is found at 

 the bottom. 



