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BOOK VIII. 



Thuringian pyrites, in which there is gold, sulphur, and vitriol, after the last 

 particle of vitriol has been obtained by heating it in water, is thrown into a 

 furnace, in which logs are placed. This furnace is very similar to an oven 

 in shape, in order that when the ore is roasted the valuable contents may not 

 fiy away with the smoke, but may adhere to the roof of the furnace. In this 

 way sulphur ver>' often hangs hke icicles from the two openings of the roof 

 through which the smoke escapes. 



A — Burning pyre which is composed of lead ore with wood placed above it. 

 B — Workman throwing ore into another area. C — Oven-shaped furnace. 

 D — Openings through which the smoke escapes. 



If pyrites or cadmia, or any other ore containing metal, possesses a good 

 deal of sulphur or bitumen, it should be so roasted that neither is lost. For 

 this purpose it is thrown on an iron plate full of holes, and roasted with char- 

 coal placed on top ; three walls support this plate, two on the sides and the 

 third at the back. Beneath the plate are placed pots containing water, into 

 which the sulphurous or bituminous vapour descends, and in the water the 

 fat accumulates and floats on the top. If it is sulphur, it is generally of a 

 yellow colour ; if bitumen, it is black like pitch. If these were not drawn 

 out they would do much harm to the metal, when the ore is being smelted. 

 When they have thus been separated they prove of some service to man, 

 especially the sulphurous kind. From the vapour which is carried down, not 



