ITALY. LETTER. XX. 283 



fummit is a fiat, which is furrounded with fome 

 hills. On the (loping fide of fuch a hill towards 

 the valley, appear continual flames ; which being 

 ever to be feen, have caufed this hill to be called 

 Pietra Mala. The calcareous Apennines are to 

 the left. The flaming place is covered with earth, 

 and loofe fepc.rated lime, clay, and marl ftones. 

 Every circurnftance fpeaks a violent devaftation. 

 The whole is furrounded with grafs and corn. 

 The flaming place has properly but fix feet diame- 

 ter, and the flames appear between and upon the 

 before-mentioned ftones. The marl and clay- 

 Hones are hardened by them. The calcareous 

 ones are rather calcined and diflblved. The flames 

 are exceedingly clear, and yellowilh- white as 

 arifing from burning oil. They have a faint 

 fmell of petroleum, and depofit by its confump- 

 tiqn a fine fod upon the furrounding ftones. They 

 rife about two feet above the ground, give no 

 mark of any fulphureous acid, grow ftronger after 

 WCL weather, and fainter in dry fummers. This I 

 was afiured by the neighbouring people. Among; 

 the loofe feparated ftones of this place I obferved 

 fragments of Serpentine-ftone * aiid calcareous 

 poms or tophus. 



* Mr. Guettard has found likewife Gabbro or Serpentine- 

 ftone in an old extinft volcano between Rome and Loretto. Tho* 

 I mean not hence to draw too rafli or falfe conclufions of this 



(tone's 



