44 EXPERIMENTS on WHlNStONE and LAVA. 



the fuperincumbent mafs, many important phenomena of the 

 mineral kingdom, which he has thus reconciled to his fy- 

 flem. 



One necelTary confequence of the pofition of thefc bodies, 

 feems, however, to have been overlooked by Dr Hutton him- 

 felf : I mean, that, after their fufion, they mull have cooled 

 very flowly ; and it appeared to me probable, on that account, 

 that, during their congelation, a cryftallization had taken place, 

 with more or lefs regularity, producing the ftony and cry- 

 flallized ftructure, common to all unftratified fubftances, 

 from the large grained granite, to the fine grained and 

 almoft homogeneous bafalt. This conjecture derived addi- 

 tional probability from an accident fimilar to thofe former- 

 ly obferved by Mr Keir, which had juft happened at Leith : 

 a large glafs-houfe pot, filled with green bottle glafs in fu- 

 fion, having cooled flowly, its contents had loft every cha- 

 racter of glafs, and had completely afTumed the ftony ftruc- 

 ture. 



These views made part of a paper which I had the ho-- 

 nour of laying before this Society in 1 790 * ; and about the 

 fame time I determined to fubmit my opinions to the teft 

 of experiment. I communicated this intention to all my 

 friends, -and in particular to Dr Hutton; from him, how- 

 ever, I received but little encouragement. He was impreffed 

 with the Tdea, that the heat to which the mineral kingdom 

 has been expofed was of fuch intenfity, as to lie far beyond 

 the reach of our imitation, and that the operations of nature 

 were performed on fo great a fcale, compared to that of 

 our experiments, that no inference could properly be drawn 



from 



* Particular reafons Induced me not to publifh this paper at full length; but*, 

 wifhing to preferve a record of fome opinions peculiar to myfelf which it contain- 

 ed, I introduced a fhort abftracVof it into the Hiftory of the Tranfaclions, 



