64 TAAVELS THROUGH 



ifblate and conic. "They are furrounded with th 

 fcaglia ; which confifts of calcareous beds, crofled 

 by black horn-iione veins, and is obliquely fu- 

 perincumbent to their fides, feeming to have co- 

 .vered the whole plain in which they arofe. This 

 happened by the effufion of the lava, which 

 through their crater ran down on every fide, and 

 not only heightened their fummit, but thickened 

 their periphery to a conical elevation. 



I cannot finifh without taking notice of the mi- 

 nerals, which now and then are found in volcanic 

 countries, and have been occafioned either by fub- 

 limation and ftearhs of the fubterraneous fire, or 

 by its vomiting the metallic bodies, which it mec 

 with under ground and irtclofed into the lava. 



To fublimation ought to be afcribed the/#//>#r, 

 which in fome volcanic countries appears In the 

 furface of the foil ; and vitriol is owing to fulphxK 

 cous acid and iron, as alum to its penetrating clay 

 or argillaceous ftones, and gypfum of felenites to its 

 uniting with lime. The cinnabar, which appea/ed 

 in the furface of the foil at Silvena nella Contea di 

 S. Fiore, had undoubtedly the fame origin. But, in 

 refpect to metals, there is no probability of finding 

 any veins in the lava's; neverthelefs, there are fome- 

 times in the diftrictof Vicenza metallic lavas in- 

 cluded iri limeftone fiflltres. All lavas contain fome 

 iron, but in different proportion 5 and two large rich 



iron- 



