l68 TRAVELS THROUGH 



very often native alum is found flicking. Na- 

 ture wants here no artificial affiftance, but the bare 

 accumulating of rlay in fuch places where the 

 acid fleams are mod frequent. 



Mr. Beaume has proved, in his quoted Treatife, 

 that fome fulphureous acid clofe connected to 

 much vitrefcent earth produces clay ; but that by 

 a greater quantity of acid the clay becomes alu- 

 minousthe very thing which happens in Solfa- 

 tara, and is pra&iled every day by the ignorant 

 unphilofophical alum-makers, in gathering clay 

 from the furface of the floor and the inclofing 

 rocks, and pat-ting' it in heaps around thofe places 

 of the floor whence the fulphureous fleams arife 

 (Irongefl, to have it the more penetrated and en- 

 riched by alum. This being clone, they bring the 

 clay into open tubs, and lixiviate it with water 

 from the Pifciarelle, which is alfo fomewhat alumi- 

 nous. The cleared brine is afterwards put into 

 fquare lead-pans, which to the brim are dug into 

 the hot bottom of the Solfatara. The fubterra- 

 neous heat makes it boil ; and, to flrengthen the 

 aluminous water, they put large pieces of hard 

 aluminous rocks into it. Being fufficiently evapo- 

 rated, they mix feme urine or pot-afhes into it, 

 in order to take away the fuperfluous acid, and 

 then put it, without any percolation, to cryftal- 

 Jize in fmall round tubs. That is the whole mani- 

 pulation 



