( 220 ) 



iumjiar pr'tfms — RefleSlions and corollaries 

 '—The Eugatfean mountains once were 

 iflajidsy like thofe of Po7ivs>a^ the Eoliany 

 Safitorine^ ^c. — Their prodigious afiiiqui- 

 ty^ and vicinity to civilized places^ two 

 caufes of the great chajiges they have un- 

 dcrgone — Their lavas analogous to thofe 

 of other volcanos^ in having rocks for their . 

 bafe — Comparifon between the rocks of 

 ether volcanos and thofe of the Euganean 

 mountains — Immeife depth of thefe rocks^ 

 ivhich would remain unknown to men 

 were it not for volca?ios — Three different 

 bafes in the Euganean rocks ^ defer vi7ig ob- 

 fervation : the feltfpar in the mafs^ the 

 volcani%ed petrofilex^ extremely refembling 

 the natural^ and the pitch-fone — Volcanos 

 ivhich have fiot this fone^ and others in 

 ivhich it is found more or lefs — Magnefa 

 7iot me of the elements of the pitch-fone of 

 volcanos^ as fume have thought — Interef- 

 ing obfervaiion of the change of petrcflex 

 into pitch-fone — Chemical analyfis of thefe 

 two fones agreeing with this obfervation — 

 FrobablUty that fome volcanic pitch-foncs 



are 



