ITALY. LETTER XV. 211 



tion of a reddiih felenite -, and in the boiling they 

 mix in the liquor feme lime * and urine. 



The fupports of the pans are rmde of a grey 

 lava with large white cryftalline fherl-prifms, 

 whofe quantity exceeds the mafs of the ferrumi- 

 nating lava. It is found, as they told me, in large 

 loofe pieces, at nine or ten miles diftance from 

 'Tolfa i and it refembles much the lava of. a 

 volcanic hill, called S. Flora in Tofcana, which I 

 have feen, and (hall defcribe in my following 

 Letters. 



. The Tolfa alum-works are faid to have been 

 difcovered in former times by a man, who, having 

 been long time a flave in Turkey, and worked 

 there in fome alum-works, gueffed by the Ilex 

 Aquifoliunt) common about 'Tolfa, that there muft 

 be aluminous works in the neighbourhood. But 

 this fhrub is found in many places where no 

 alum is to be had at all. 



Monfignor Borgia at Rome, who had the good- 

 nefs to provide us with recommendations to Ci- 

 vita Vecchia and Tolfa, and who, notwithftand- 

 ing his troublefome infpe&ion of the Collegium de 

 propaganda fide, preferves a good tafle for every 



fcience, has made in his travels through the Ro- 

 3jui\?r zssnifcjjip o 



* If this be the cafe, the felenite is in no refpea a fubftan- 

 tisl part of the Tolfa alum-ftone, as the author feems inclined 

 to fuppole. 



P 2 man 



