ATTRACTION. i4,j 



FIG. 10. Dodecahedron FIG. 11. Triangular or 



with triangular faces. three sided prism. 



" The primitive forms, by a further dissection of the octahedron, 

 hexangular prism, and dodecahedra, in directions, not parallel to the 

 sides, may be reduced into three forms : the tetrahedron, or simplest 

 solid, the triangular prism, or the most simple prism ; and the paral- 

 lelopiped, including the cube, rhomboid, and four sided prism. As 

 it is in size only, that integrant atoms can be altered by cleavage ; it 

 it is inferred that if the dissections were continued until the smallest 

 integrant atom should be developed, its form would be the same as that 

 of the parent mass. Hence also the inference has arisen, that the only 

 forms, which belong to integrant atoms, are those above mentioned." 

 It is remarkable that (the sphere and spheroids only being except- 

 ed,) these three forms are the simplest of solids. As three lines 

 are the smallest number that can include a superficies, so four planes 

 are the smallest number that can include a solid ; the integrant 

 molecules above named have successively, four, five, and six faces. 



(n.) The actual or secondary forms are built up, by the union of 

 Integrant particles, to produce the primitive form, and then by the 

 addition of other particles, single or in groups, upon the faces of the 

 primitive form . 



(o.) The dev elopement of these processes, constitutes the theory of 

 crystallization, proceeding according to the laws of decrement. 



1. Parallel to the edges 2. Parallel to the diagonal 3. Par- 

 allel to a line intermediate between the side and the diagonal ; or, 

 parallel to either of the above, but proceeding by three in breadth, 

 and two in height, or the reverse, or by such a ratio that the relation 

 of height and breadth, in the ranges of particles, shall be expressed 

 by a proper vulgar fraction ; this supposed arrangement of integrant 

 particles is called 4. Mixed decrement. 



(p.) A minute, consideration of this subject, belongs to mineralogy 

 but the following illustrations will render the descriptions of incre- 

 ment and decrement intelligible. 



Conversion of a cube into a dodecahedron. 



" If a cube be increased by layers of particles, applied to all its 

 sides, the edges of the layers being parallel to those of the cube, and 



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