56 EXPERIMENTS on WHINSTONE and LAVA. 



produced a uniform ftony cryftallite, greatly refembling the 

 original. 



It has thus been fhown, that all the whins employed afTume, 

 after fufion, a ftony character, in confequence of flow cooling ; 

 and the fuccefs of thefe experiments, with fo many varieties, 

 entitles us to afcribe the fame property to the whole clafs. The 

 arguments, therefore, againft the fubterraneous fufion of whin- 

 ftone, derived from its ftony character, feem now to be fully 

 refuted. 



Experiments on Lava. 



In the investigation of Dr Hutton's fyftem, great advantage 

 may be expected from an examination of lavas. They have un- 

 doubtedly flowed on the furface by means of heat ; and whin- 

 ftone, according to his hypothefis, having flowed in the bowels 

 of the earth by the influence of the fame agent, the two clafTes 

 ought to poflefs many properties in common, by which the 

 hiftory of both may be illuftrated. 



I have been enabled to inftitute a comparifon between them, 

 by -means of a cabinet of volcanic productions which I collect- 

 ed in 1785, in company with Dr J. Home of this Society, 

 on Vefuvius, iEtna, and the Lipari Ifles. On this occafion 

 we were greatly aflifted by the celebrated M. Dolomieu *, 

 who accompanied us in part of our expedition. This author 

 complains, in his writings, that travellers, in collecting volcanic 

 productions, have brought away only the fuperficial fcoria of 

 lavas, which nearly refemble each other in all cafes, and convey 



no 



* Though I differ widely from this gentleman in many of his theoretical opi- 

 nions, I cannot too flrongly exprefs my admiration of his merit as a natural hiftorian, 

 His defcriptions of countries, as well as of minerals, prefent the moft lively repre- 

 fentations to the mind of the reader, which, in the numerous inftances I have witneC- 

 £ed, are perfectly correct. . ' 



