t MOLECULES. 39 



trihedral prisms; and fig. 61 shews the trihedral 

 prism separately. 



Fig. 62. 



If we reduce a cube of jluate of lime to fragments, 

 we shall find that it does not split in directions paral- 

 lel to its planes as galena does, but that it splits 

 obliquely. If we suppose fig. 62 a cube of fluor, and 

 we apply the edge of a knife to the diagonal line a b y 

 and strike it in the direction of c, we may remove the 

 solid angle a b e c. 



Fig. 63. 



If we again apply the edge of the knife to the same 

 line a b, and strike it in the direction of f, we may 

 remove another solid angle a bfd; applying the 

 knife again in the direction of the line c c?, and strik- 

 ing successively in the directions g, and h, we may 

 remove two other solid angles. 



The new solid produced by these cleavages is re- 

 presented by fig. 63. 



