THE PROBLEM OF CRYSTALLIZATION. 



53 



the vertex of the pyramid with a force proportional to its distance 

 from the vertex. 



The proper mathematical interpretation of the stated force law in 

 crystals shows its perfect identity with the Newtonian law of gravita- 

 tion, according to which 

 every particle of the uni- 

 verse attracts every other 

 particle, with a force pro- 

 portional to the product of 

 the masses, and inversely 

 as the square of the dis- 

 tance. Thus, the symme- 

 try, beauty, and definite- 

 ness displayed in the in- 

 finite variety of crystal 

 forms have necessarily im- 

 pressed themselves upon 

 the observing mind, ever 

 since the remote period of 

 the dawn of the natural 

 sciences, as the silent car- 

 riers of a law of profound 

 influence upon the nature 

 of substances. That this 

 law, in obedience to which 

 the planets are swept 

 through space, should also regulate the position of the tiny crystal mole- 

 cule, is a striking instance of the truism, in accordance with which the 

 essences of things are not affected by their magnitude, and without 

 which the human mind could not conceive the interaction of the forces 

 of Nature. 



The stated law also governs the interaction of electrical masses. 

 Now, the only reason why it applies to the ultimate particles of a crys- 

 tal is their tetrad arrangement. Hence 

 the tetrad grouping of the ultimate par- 

 ticles, and therefore crystallization, is 

 caused by an agent which acts like elec- 

 tricity. Very probably it is electricity 

 itself, as is evidenced by the electrical 

 properties of certain crystal forms, which 

 appear to establish an intimate causal 

 connection between the structure of 



crystals and this agent. This is illustrated in many so-called hemi- 

 morphic forms : these are forms in which opposite ends of a crystal, 

 instead of being bounded by faces of the same form, are bounded 

 by faces belonging to different forms. This phenomenon occurs in 



Fig. 18. 



Fig. 19. 



