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many places, includes extraneous bodies, 

 feme of which are of conlidcrable import- 

 ance to volcanic enquiries. Thefe are 

 fmall pieces of hom-flone pofleffing that 

 porofity which characterizes them for true 

 lavas. One of the fpecimens above men- 

 tioned contains a fragment of this kind 

 two inches in thicknefs, extremely perfedt, 

 and very porous. The vacuities are round 

 and elliptical : fatisfacflory figns that it has 

 made a part of fome current. 



The other lava from the fame mountain 

 refembles the former, as far, at leaft, as can 

 be judged from the fpecimens I brought 

 away, in its colour, w^hich is that of tur- 

 pentine, only much darker and lefs lively.; 

 and in its confidence ; except that it forms 

 unmixed mafles, and contains amorphous 

 feltfpars, of Uttle or no brilliancy. Among 

 all the pitch-ftone lavas of the Euganean 

 mountains that fell under my obfervation, 

 this is the moft compact, heavy, and hard. 

 The eye alone, however, is fufficient to 

 .difcern the great difference between thefe 

 S 4 pitch- 



