210 TRAVELS THROUGH 



The blafted Hones are calcined in furnaces, 

 which have an inverted conical form. They 

 are in the open fields clofe together, fur- 

 rounded and feparated by a covering of turf and 

 mould. The upper diameter is about eight feet. 

 They are filled at the bottom with wood, and then 

 heaped with alum-Hone, which appears above the 

 furnaces as an accumulated cone, nine or ten feet 

 high, which is nearly anfvvering to the depth of 

 the furnace. Then fire is let to the wood by a 

 fquare vent near the bottom, and the whole" is 

 burnt down in about three hours time ; which is, 

 as they told me, the requifite time for burning : 

 after which the heated Hones are carried to the 

 boiling-houfe, diftant about one Italian mile from 

 .the quarries. Here they are put into large pits, 

 or fquare wooden refervoirs, half funk into the 

 ground ; where they are fleeped in a convenient 

 quantity of water, which, after fufficient diflblution 

 of the alum, is by troughs conveyed into the 

 alum-houfe, and in large fquare wooden fettlers, 

 that the dregs may fettle at the bottom. This 

 done, the clear lixivium is poured into brafs pans, 

 and after fufficient boiling conveyed into wooden 

 coolers, on whofe fides the alum cryftallizes white 

 and reddifh. Before the infpiflated brine be con- 

 veyed into the cooler, they flop it for fome time 

 jn the troughs, in order to facilitate the precipita- 

 7 tion 



