Microscopical Essays. 6Si 



figured mafles, like native cryftal ; from which refemblance the 

 word crystallization has evidently been taken.* 



But modern chemifts and naturalifts have much extended this 

 expreffion, and it now lignifies a regular arrangement of" the 

 parts of any body which is capable of it, whether the mafles fo 

 arranged be tranfparent or not. Thus opake ft ones, pyrites, and 

 minerals, when regularly formed, are faid to be cryftallized, as 

 well as tranfparent ftones and falts. 



The opacity and tranfparency of fubftances are juftly difre- 

 garded, in confidering whether they be cryftallized or not ; for 

 thefe qualities are perfectly indifferent to the regular arrangement 

 of the integrant parts of fubftances, which is the eflential objecl of 

 cryftallization. 



This being eftabli fried, cryftallization may be defined, an 

 operation by which the integrant parts of a body, feparated from 

 each other by the interpofuion of a fluid, are difpofed to unite 

 again, and to form folid, regular, and uniform mafles. 



To underftand as much as we can of the mechanifm of cryftal- 

 lization, we muft remark, 



i . That the integrant parts of all bodies have a tendency to 

 each other, by which they approach, unite, and adhere toge- 

 ther, when not prevented by an obftacle. 



4 O 2. That 



* Macquer's Di&ionary of Chemlftry, Art. Cryftallization. 



