l%6 TRAVELS THROUGH 



terraneous inflammations are demonftrable by ex- 

 perimental philofophy. They are many. But it 

 is impoffible exactly to determine to what they are 

 owing, whether to water and pyrites, or to a fer- 

 mentation of calcareous materials produced by 

 acids or waters. According to general report, 

 pyrites have been thrown out, though in fmall 

 quantities ; but fublimated fulphur is very com- 

 mon on its fmoking funnel. 



The amazing quantities of lava and aflhes, vo- 

 mited in fo many eruptions during fo many cen- 

 turies, prove that Vefuvius is hollow, and that 

 there are befides, under ground, large holes and 

 refervoirs of inflammable and vitrefcent materials. 

 The common finking of the volcanos into flat 

 pools countenances that opinion. However, the 

 lava-eruptions out of the upper funnel can be pro- 

 duced by its fermentation and ebullition, which 

 overflowing the funnel have fuccefiively raifed it, 

 and will continue to do fo, till the whole fire-built 

 conftruction link into the ground. 



The undermoft and inner part of Vefuvius 

 confifts probably of lavas, afhes, and burnt ma- 

 terials. The remains of funk and extindt vol- 

 canos prove it. Monte Somma and Ottajano is the 

 beft evidence to the purpofe. This mountain 

 confifts of many horizontal or fomewhat dipping 

 beds, each one or two feet thick ; and thefe are 



compofed. 



