ft* Cryfiallizaticn. [Book I. 



body in the menftruum, or fluid, which is a pro- 

 per folvent for one or both of the component Jub- 

 ilances *. 



It may be proper, before the conclufion of this fec- 

 tion, to add a few words concerning one of the moft 

 curious effects of the attraction of combination, name- 

 ly, cryflallization. The word cryftal is derived from 

 cryos (froft), zndfallo (to contract) ; it was originally 

 confined to a particular diaphanous ftone refcinbling 

 clear ice, and was probably afterwards extended to all 

 bodies which were tranfparent, and had their particles 

 difpofed in a regular manner, particularly the different 

 fpecies of falts. It is now expreflive of that regular 

 order or dilpofition, in which the particles of inert 

 bodies arrange themfelves on pafling from a fluid to a 

 folid flate. This difpofition of the particles is, how- 

 ever, by no means the fame in all fubftances, but va- 

 ries almoil infinitely in different bodies. Thus com- 

 mon fait cryftallizes into a cubic form, falt-petre into 

 that of oblong pillars with fix fides, cubic nitre into 

 the rhomboidal form, vitriolared tartar and Glauber's 

 lalt into a mafs of four or fix fides. Each fpecies of 

 fait preferves its peculiar form however frequently the 

 procefs of diflblving it is repeated, and equally in the 

 fmalleft mafles which the microfcope renders vifible, 

 and in the largeft which art or nature have been able 

 to produce f . 



It 



* Kirwan's Mineralogy. 



} ' If what has been faid relative to cryftallization be not per- 

 fe<EUy intelligible to the reader, I would advife him to make the 

 ' following eafy experiment, which will give him a better notion 

 of the matter than a thoufand words. Into a bafori full of boil- 



* ing water, put as much faltpetre as the water will take up; if 



the faltpetre was purified, the tranfparency of the water will not 

 ' be injured, it will llill appear to be a homogeneous fluid: when 



the 



