r lo ] 



and laft of all, the felfpar fliould coalefcc and congeal, (at lead 

 in the Baronet's fuppofitlon) in regular cryftals ; now as the 

 . cryftallizations of thele three fpecies of ftone take place each at 

 a diftindl portion of time, each fliould occupy alfo a diftind 

 portion of fpace, the firfl; fet of cryflals being loweft, the next 

 over that and the laft uppermoft, as we find to happen when 

 falts of very different folubility and yet in equal quantity are 

 diffolved and cryftallized in water, or vphen fubftances of dif- 

 ferent degrees of Volatility are fublimed by fire. Now, among 

 the immenfe mafles of granite that have been obferved and 

 examined in various parts of the globe, not above half a dozen 

 have occurred in which the three conftituent parts of granite 

 were regularly cryftallized, very few in which diflin(5l layers of 

 each were feen, and none at all confifting of diftindl regular 

 cryftals of each, fuperimpofed on each other. On the contrary 

 in far the greater number of granitic mafles the three above 

 named conftituent mafles lie intermixed with each other in the 

 moft confufed and irregular manner, and without any appear- 

 ance of regular cryftallization ; infomuch that none can fay, 

 from bare infpedtion only, which was cryftalized firft, and which 

 laft. — nay granitic maflTes not unfrequently occur, in which it 

 is evident that the mica muft have cryftallized contempora- 

 neoufly with the quartz, for in breaking the quartzy part flakes 

 of mica are found within it. See 6, Saufs. § 1621. 



Lastly, I muft add, that even on the fuppofition that diftindl 

 cryftals of quartz, felfpar and mica could be produced by 



fufion, 



