374 



BOOK IX. 



bellows in rotation. Finally we must not omit to state that this is only one 

 of many such axles having cams and a water-wheel. 



I have arrived thus far with many words, and yet it is not unseasonable 

 that I have in this place pursued the subject minutely, since the smelting of all 

 the metals, to which I am about to proceed, could not be undertaken without 

 it. 



The ores of gold, silver, copper, and lead, are smelted in a furnace by 

 four different methods. The first method is for the rich ores of gold or silver, 

 the second for the mediocre ores, the third for the poor ores, and the fourth 

 method is for those ores which contain copper or lead, whether they contain 

 precious metals or are wanting in them. The smelting of the first ores is 

 performed in the furnace of which the tap-hole is intermittently closed ; the 

 other three ores are melted in furnaces of which the tap-holes are always 

 open. 



First, I will speak of the manner in which the furnaces are prepared for 

 the smelting of the ores, and of the first method of smelting. The powder 

 from which the hearth and forehearth should be made is composed of char- 

 coal and earth (clay ?). The charcoal is crushed by the stamps in a mortar- 

 box, the front of which is closed by a board at the top, while the charcoal. 



A — Tub. B — Sieve. C — Rods. D — Bench-frame. 



