INDEX. 503 



right rectangular prism, 341.- to the right rhombic 

 prism, 343. to the right; oblique-angled prism, 347. 

 to the oblique rhombic prism, 351. to the doubly 

 oblique prism, 355. to the hexagonal prism, 356. 

 to the rhomboid, 360. applied to a particular case, 

 378. 



Carbonate of Lime, see Lime, carbonate. 

 Cleavage, the direction in which a crystal may be split, 1. 

 on what its direction is supposed to depend, 56. two 

 or more sets of, may exist in the same crystal, viz. 

 primary set, supernumerary sets, 56. planes, generally 

 similar, when the primary planes to which they are 

 respectively parallel, are similar, 57. more easy in 

 one direction of the crystal than another, when the 

 primary planes are not similar, 57. primary set may 

 lie in one, two, or more different directions, hence the 

 terms, single cleavage, double, threefold, &c. 58. 

 solids produced by, do not necessarily represent the 

 molecules of crystals, but are sometimes imperfect 

 primary forms, 59 to 65. how it might ultimately pro- 

 duce an octahedron from the tetrahedron, by the remo- 

 val of cubic molecules, 65. primary form may some- 

 times be developed by, 79. 

 Cleaving a crystal, is splitting it, 1. 

 Crystal, A, defined, 1. 



Crystals, may be split in different directions, 1. formed by 

 aggregation of homogeneous molecules, 5. when said 

 to be in position, 17. how supposed to increase in size, 

 17. by added molecules arranged in plates, 18. which 

 are entire or defective, 18. when defective, the de- 

 fect is termed a decrement, and a secondary plane is 

 produced, 19. and the crystal is then said to be 

 modified, 24. their formation attempted to be explained 

 by Mr. Beudant, 76. hemitrope and intersected, 88. 

 epigene and pseudomorphous, 93. differing in spe- 

 cies may belong to the same class or to different classes 

 of primary forms, 95. the nature of the differences in 

 relation to different classes, 96. method of reading 

 them, 223. how to describe them, 229. methods of 

 drawing the figures of, 402 to 438. 

 Crystallography, its object, 1. 



Cube, defined, 6. its axisj 13. its molecule a cube, 37. 

 its relation, as shewn by cleavage, to the regular octa- 

 hedron, 39, 40. to the rhombic dodecahedron, 44. 

 to the regular tetrahedron, 84. its modifications, 107. 



