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flioerls or feltfpars ; and, in their external 

 charaders, feem not to difFer eiTentially 

 from the lava itfelf. 



Among the number of the pitch-ftone 

 lavas- already mentioned there is one which 

 muit peculiarly attracfi the attention of vol- 

 canifts, from the pumices it contains. Mon- 

 felice, one of the Euganean mountains, 

 whicn ftand^ detached, and is of a moderate 

 extent and height, is partly compofed of a 

 white argillaceous i .va, of an earthy afpedt, 

 in which we find this peculiarity ; only 

 that, while t'le pumices of the pitch-ftone 

 lava are derived from the parts of it being 

 dilated and tumefied by gafeous elaftic fub- 

 ftances, thofc of the prefent lava appear to 

 be adventitious, confifting in white globules 

 eafily feparable from the bafe, from which 

 probably they were taken when it was in 

 a fluid flate. Except that they are lefs, 

 they confiderably refemble the pumiceous 

 globules of Pompeii near Vefuvius ; and 

 both, in the furnace, produce a fimilar 

 enamel. 



U 2 This 



