34^ ¥be Uses 



prefent they ufe a furnace, with a cavity and two 

 mouths, and divided in two parts, and having over 

 the fmoke-vent fuch another pafiage or funnel, as 

 above defcribed, though not all of mafonry, but part- 

 ly of wood, nor quite ftraight, but with three or 

 four crooks or windings, againft which the arfcnic- 

 fume may ftrike, and the meal fettle. The meal, 

 in order to be fitted for market, muft be fublimed 

 like a cinnabar, which is performed in a hut, fome- 

 what high and open above, like a roaft-houfe, 

 wherein is built an oblong, vaulted furnace, about 

 three feet high from the earth, and fo long, that 

 three plate-hoods, the width of each afunder, may 

 ftand thereon. Above, in the vault of the furnace, 

 three round holes are left with each a difh of caft- 

 iron, and on each dim an iron hood of plate, be- 

 low fo large and round as to fit the difhes, and ta- 

 pering to an aperture of the fize of a man's arm. 

 After fecuring the above hoods on the dimes, a 

 quantity of the arfenic-mcsLl is fhot through the 

 aperture into the difh, fire made in the furnace, and 

 the meal directly fublimes into the hoods, being 

 often ftirred in the difh, by pafling a (tick through 

 the aperture ; and when a quantity has fublimed, 

 they convey in more meal, 'till the hoods become 

 fufRciently charged, and generally they let the fire 

 in the furnace go out every evening, the aperture 

 always remaining open : but the operators muft bind 

 up mouth and nofe in charging and ftirring the 

 meal. Now, in order to procure yellow arfenic> 

 amongft three centners of meal, between two and 

 four pounds of fulphur are added, which being fu- 

 blimed together, a beautiful yellow arfenic is pro- 

 cured *. Thus far M. Rofsler. 



IV. To 



* Id. ib. Lib. IV. c. it. p. T57. feq. 



