140 



from the solvent, and the solvent, may account for immense 

 variety. This, however, is a very rare example, identifying 

 a new kind of form, and bespeaking another source of 

 boundless variety. The crystals seem to be formed of plates 

 belonging to the cube and cubo-octaedron, passing in a 

 more or less continued line of elongation, forming a sort of 

 wall-like appearance in various directions, and may perhaps 

 be compared to a tall weak wall on an irregular foundation, 

 bending before it was hardened by drying. The crystalli- 

 zation of Pearl-spar, tab. \g, lower Jigure, which curves, 

 seems governed by a different law : the molecules seem to 

 slip while depositing ; and the Sulphate of Lime, tab. 68, 

 seems to bend from an elastic property. 



