the AIM Ham/ s Theories of Crystallography. 165 



the application of them. For it is an incontestable fact, 

 that by a series of arbitrary truncations we may pass insen* 

 sibly from any given form to any other. Grounded on this 

 principle, and seconded by Mr. de ITsle's ingenuity, any 

 form may become primitive, and any other deduced from 

 it. Now, as the combinations are infinite, a multitude of 

 tables may be constructed ; forms of the same species may 

 be dispersed in different tables ; the most simple of each 

 table will be the primitive ; therefore forms of the same spe- 

 cies will have different primitives. But when by the same 

 principle both sides of the question can be proved, nothing 

 is proved. 



To say the most simple form must be the primitive, is 

 an illusion ; for we know not what is the most simple for 

 nature. With our feeble organs and confined senses we 

 can form no judgment of simple when the operations of 

 nature are in question. Nature embraces the entire uni- 

 verse ; her laws are simple ; but the combinations made 

 according to those laws are unbounded, therefore compli- 

 cated. 



Let u« not forget, however, that the idea of truncations, 

 and the idea of taking the most simple form for the primi- 

 tive, are so natural, that they must have been the first to 

 present themselves to the man who was opening the career. 

 \\ Often," says the Abbe Haiiy, (vol. i. p. 14.) « a more 

 compound form only differs from a more simple one by 

 certain little faces, which may be produced by sections ei- 

 ther at the solid angles, or on the edges of the simpler form/* 

 And in a note he says : " This was the observation which 

 gave the celebrated Rome de ITsle the idea of his system of 

 truncations, that he might successively deduce from each 

 other the different varieties of crystalline forms assumed by 

 the same substance." 



Mr. de Tlsle terminates the introduction to his work by 

 certain axioms, as he styles them, the 2d and 1 6th. of which 

 are as follow : 



II. " Every angular polyedron, or every crystallized sub- 

 stance, is a salt in the most extended acceptation of thai 

 term." 



XVI. " Every saline substance whose constituent parts 

 are perfectly saturated and combined, affects the cubic form, 

 or its inverse the octa'edron ; whereas the salts which are 

 not neuter, or whose constituent parts are not exactly comr 

 bined, affect either the prismatic or the rhomboida I forms." 



I need scarcely observe that, to treat such axioms only as 

 doubtful, would' be treating them kindly. The other axioms 



Vol. 19. No. 74. July 1804. N are 



