Theory of CryjJallizatioft. 3 J 



*ii a tubular piece of the before-mentioned fpongia villofa 

 firft induced mc to repeat the fame experiment on other 

 kinds of tough fea fponges. 



w, 



X. On the Theory of the Structure of Cryjiah, 

 [With a Plate, No. II.] 



HEN we reflect on the rapid progrefs which has been 

 of late made in mod branches of natural knowledge, and 

 particularly in chemiftry and mineralogy, and confider how 

 much thefe may be facilitated by a competent knowledge of 

 thofe regular forms which all mineral and faline fubftances 

 affume, in certain cireumftances ; it appears furprifing, that, 

 though we have a number df books which treat on chemif- 

 try, we have not one Englifli work on the theory of the 

 ftru&ure of cryltals. To remedy this defe£t in fome de- 

 gree, and as an introduction to original papers on the fub-, 

 je£l promifed to us by an eminent mineralogift, we think 

 proper to lay before our readers the following tranflation of 



The Abbe HaVY's Theory of Gryfiallizaiioh. From 

 Vol. XVII. of the Annales de Chimie. 



I GAVE in this Journal, fome years ago, a fhort account 

 of the theory of cryftallization ; but that paper may be 

 confidered only as a fhort fketch, and more calculated for 

 thofe who wifh not to be entirely ignorant of the fubje£t, 

 than for thofe defirous of becoming thoroughly acquainted 

 With its principles and reiults. In the prefent paper I pro- 

 pofe to afford the latter an opportunity of obtaining their 

 object, by prefenting them with the theory required, and 

 With all the facts neceffary to give them a juft idea of the 

 laws to which it is fubjeel, and of the progr fs by which it 

 ha$ been carried to fuch a degree of generality that an im- 

 D 2 menfe 



