Mineral Causes. 117 



law in their crystallisation. Alum is composed of 

 three metallic elements — aluminium, potassium, and 

 hydrogen ; and two non-metallics, oxygen and sulphur. 

 It is thus a dual or sexual substance, built up of com- 

 pound molecules. In an evaporating solution of alum, 

 consequently, the separate elementary atoms, discover- 

 ing their affinities, rush together in certain proportions 

 and form molecules of alum : the acting: law beiner 

 the dual one of sexual-material-selection. Nextly, the 

 molecules in turn aggregate into alum crystals by the 

 primary law of like-material-attraction, the process 

 and the results throughout being wholly automatic. 

 Further, when we realise that the same laws in a 

 compound solution build up, besides alum crystals, 

 separate crystals of copper sulphate — each law, so to 

 speak, interpenetrating the other — we are filled with 

 wonder at the infinite diffusion, unerring accuracy, 

 and infallible " intelligence " of natural automata. 



(c) The fact that better order, larger crystals, and 

 more beautiful forms are produced by slow than fast 

 selection indicates, in addition to the preceding laws, 

 the influence of a methodical form-selector or design- 

 ing power in nature. This power, as already demon- 

 strated, is the other automatic law — polarity. 



All substances through their atomic, magnetic, or 

 primary constitution are themselves magnetic ; hence, 

 when any substance is in a condition to indicate form, 

 as in a slowly evaporating crystalline solution, the 

 polar laws strike in between the laws of like and 

 sexnal-matcrial-selections, and direct that while these 



