ITALY. LETTER VI. 71 



have been defcribed by Count Vincenzo Mafmi in 

 his poem // Zolfo, in three books, printed a fecond 

 time at Bologna, 1762, in 4^0. The above plaifter 

 is employed in mouldings in the china-manu- 

 factory at Venice. 



2. Ludus Helmontii, or cubical marl-done, fer- 

 ruminated by calcareous fpar-veins, from rio delk 

 maravtglie pre/o al Martignone ful Bolognefe. 



3. Several petrified fhells from the Bolognefe. 

 The fmaller, and moft remarkable ones, have been 

 defcribed by Mr. Bajfi, in the Afta Inflltuti Bom- 

 menjis. 



4. The celebrated Lapis Bononienfis^ a felenitical 

 fpar; which, after a convenient uftulatton, grows 

 phofphorefcent, and has been, together with other 

 phofphorefcent ftones, very well defcribed by Mr. 

 Markgraf at Berlin. The waiter of the Infti- 

 tute makes, of this {lone and Tragacanth, 

 ftars, and other fuch things, which light in the 

 dark. He fells them pretty high to travellers, 

 who believe him, on his word, to be the only 

 man poffefled of this arcanum. The Lapis Bo- 

 nonienfis is found in pieces' of a white opaque, 

 or femi-pellucid water-colour, either entirely foiid 

 or in nodules, ftriated from the centre. It is 

 found detached and loofe in monfe Paterno, three 

 Italian miles diftant from Bologna, in clay or 

 marl, whence it is warned by rain. 



F 4 5- T ' 



