455 On Crystallography* 



The Isotonic Scale*', Beats in 15'', 



(The Vibrations communicatee] by Mr. Faret.) 



LXVIU. On Crystallography. %M. Hauy. Translated 

 from the last Paris Edition of his Traite de Mineralogie. 



[Conunuedfrom p. 363.] 

 GEOMETRICAL CHARACTERS OF CRYSTALS. 



16. Forms, Nucleus or primitive form. 



It is very rare to find a mineral under its primitive form 



fiven immediately by nature, and there is a certain num- 

 er of species in which this form is known only from the 

 results of mechanical division and by theory. The just 

 measurement of actions susceptible of producing it is only as 



* See our ixviihb volume, p. 65, and our xxixth volume, p. 347.— Edit. 



it 



