CONNEXION OF FORMS. 



17 



example of both these kinds of difference may be seen in the crys- 

 tals of Iron Pyrites, Figs. 10, 11, 12, and 13 ; 



Fig. 10. 



Fig. 11. 



Fig. 12. 



Fig. 13. 



in those of Carbonate of Lime, Figs. 14, 15, and 16; 



Fig. 14. Fig. 15. Fig. 16. 



~ c 



aid in those of Uranite. Figs. 17, 18, and 19.* 



Fig, 17. Fig. 13. Fig. 19. 



The different forms in each of these substances have a constant 

 uniformity in the value of their respective angles; and individuals 

 belonging to them, though from the most remote situations, present 

 not the slightest variation in this respect. 



* Fig. 11 is obviously, a mere modification of Fig. 10; Fig. 12 of 11, 

 the difference being, that in 12, the faces o are considerably more exten- 

 ded than in 11 ; 13 is a modification of 12, in which the faces o are pro- 

 duced so as to extinguish the planes a, seen in 11 and 12. Between Figs. 

 14 and 15, the difference is not so easily explained ; while, we have only 

 to conceive of the enlargement of c at both extremities of the prism, Fig. 

 15, in order to form Fig. 16. 



2* 



