388 BOOK IX. 



form round about the nozzles of the bellows. This process of smelting is very 

 ancient among the Tyrolese^^, but not so old among the Bohemians. 



The second method of smelting ores stands in a measure midway between 

 that one performed in a furnace of which the tap-hole is closed intermittently, 

 and the first of the methods performed in a furnace where the tap-hole is 

 always open. In this manner are smelted the ores of gold and silver that are 

 neither very rich nor very poor, but mediocre, which fuse easily and are 

 readily absorbed by the lead. It was found that in this way a large quantity 

 of ore could be smelted at one operation without much labour or great expense, 

 and could thus be alloyed with lead. This furnace has two crucibles, one of 

 which is half inside the furnace and half outside, so that the lead being put 

 into this crucible, the part of the lead which is in the furnace absorbs 

 the metals of the ores which easily fuse ; the other crucible is lower, and 

 the alloy and the molten pyrites run into it. Those who make use of this 

 method of smelting, tap the alloy of gold or silver with lead from the upper 

 crucible once or twice if need be, and throw in other lead or htharge, and 

 each absorbs that flux which is nearest. This method of smelting is in use 

 in Styria^^. 



The furnace in the third method of smelting ores has the tap-hole hke- 

 wise open, but the furnace is higher and wider than the others, and its bellows 

 are larger ; for these reasons a larger charge of the ore can be thrown into 

 it. When the mines yield a great abundance of ore for the smelter, they 

 smelt in the same furnace continuously for three days and three nights, 

 providing there be no defect either in the hearth or in the forehearth. In this 

 kind of a furnace almost every kind of accretion will be found. The fore- 

 hearth of the furnace is not unhke the forehearth of the first furnace of all, 

 except that it has a tap-hole. However, because large charges of ore 

 are smelted uninterruptedly, and the melted material runs out and the slags 

 are skimmed off, there is need for a second forehearth crucible, into which the 

 molten material runs through an opened tap-hole when the first is full. When 

 a smelter has spent twelve hours' labour on this work, another always takes his 

 place. The ores of copper and lead and the poorest ores of gold and silver 

 are smelted by this method, because they cannot be smelted by the other 

 three methods on account of the greater expense occasioned. Yet by this 

 method a centumpondium of ore containing only one or two drachmae of 

 gold, or only a half to one uncia of silver,^'' can be smelted ; because there 

 is a large amount of ore in each charge, smelting is continuous, and without 

 expensive fluxes such as lead, htharge, and hearth-lead. In this method 

 of smelting we must use only cupriferous pyrites which easily melt in the 

 fire, in truth the cakes melted out from this, if they no longer absorb 



^^Rhetos. The ancient Rhaetia comprised not only the greater part of Tyrol, 

 but also parts of Switzerland and Lombardy. The mining section was, however, in 

 Tyrol. 



^'Noricum was a region south of the Danube, embracing not only modern Styria, but 

 also parts of Austria, Salzberg, and Carinthia. 



^''One drachma of gold to a centumpondium would be (if we assume these were Roman 

 weights) 3 ozs. i dwt. Troy per short ton. One-half uncia of silver would be 12 ozs. 3 dwts. 

 per short ton. 



