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derate age. The fame antiquity is, likc-a 

 wife, probably the reafon, why in Felicuda 

 we do not find fcori^e, or fcoriaceous lavas ; 

 thefe, ufually, from their flight and feeble 

 texture, and from their lying on the furface 

 of the current, being the firft which are 

 altered and deftroyed. 



When treating of Lipari, I remarked the 

 great effeds which have been produced on 

 the products of that ifland by the fulphu- 

 reous-acid exhalations. The contrary is to 

 be obferved of Felicuda, there not being a 

 fmgle lava which exhibits the leaft fign of 

 their influence; though they all bear the 

 marks of the injuries of time and of the at- 

 mofphere. So much have I found them 

 changed, efpecially near the furface, that 

 had I not broken up the lavas to the depth 

 of fome feet, a pradice to which I had ac* 

 cuftomed myfelf in thefe refearches, I fliould 

 freouently have taken the fame lava for 

 others fpecifically different. 



Having thus defcribed the different kinds 



of 



