of the Pyrites. 33$ 



The method of working fulphur exprefly at Fri- r 

 berg, M. Rofsler * deicribes thus : c For the pur- 



■ pole, there mull be a driving and a fining fur- 



* nace, both to be properly proportioned. The 



* fulphur, or driving furnace, is built in length, in 



* fuch a manner, as between the two front, or head 

 6 walls, to admit of either eleven, thirteen, or fif- 



* teen pipes, to reach acrofs from wall to wall ; alio 



■ lower, there are either fix, feven, or eight pipes, 



* placed at a height ; over the fpaces between 

 6 thefe, another row of five, fix, or feven pipes, 



* alfo at a height, fo that each pipe may come to 



* be within the reach of the fire, and become ig- 

 4 nited. The width of this furnace muff, be de- 



* termined by the length of the pipes. Over the 

 c pipes, from one head or front wall to the other, 

 c is turned or caft a flat arch of tiles, with a num- 

 c ber of holes left, of the fize of a fmail arm, for 



* difcharging the fmoke of the wood. The pipes 



* are made of good fluff or clay, and two and a 

 1 half inches thick, and nine inches wide at the 



* mouth, which is flat in the under, and fomewhat 



* round in the upper part, and to be fo made, that 

 c a clay plate may be moved down over ir, and 



■ again removed occafionally •, from the mouth 



* they run tapering off to the other end, where the 

 4 fulphur runs out, leaving an aperture only of an 

 4 inch. Behind, where the fulphur runs out, there 



* is left on the wall a fettle, whereon the lead-pans 



* may ftand to receive the fnouts of the lower 

 c pipes •, and for each upper pipe a fmall wall is 



* raifed for thrir pans. The pans are fquare, with 



* a flat half cover, reaching half way : fome cold 



* water is put into the pans, for the fulphur to run 



* into and be quenched in. The furnace is heated 

 6 with billet-wood laid on a grate, through which 

 ' the coals may fall down. You mull be well ac- 



' quainted 

 * Berg-bauf^iegel. 1. iv. cap. 16. p. 155. 



