S6 EXPERIMENT'S on WHINSTONE and LAVJ. 



produced a uniform ftony cryftallite, greatly refembling the 

 original. 



It has thus been fliown, that all the whins employed affumc, 

 after fufion, a ftony charadler, 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 fulion of whin- 

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

 refuted. 



Experiments on Lava. 



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

 may be expecfted 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 claffes 

 ought to pofTefs many properties in common, by which the 

 hiftory of both may be illufti-ated. 



I HAVE been enabled to inftitute a comparifon between thent, 

 by means of a cabinet of volcanic produdliions which I colledl- 

 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 colledling volcanic 

 produclions, have brought away only the fuperficlal fcoria of 

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



no 



• Though I difter widely from this gentleman in many of his theoretical opi- 

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

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

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

 £ed, are perfedly correft. 



