THE LINEAR FORCE OF GROWING CRYSTALS 



3 2 9 



diffusion through increased viscosity and in interposing an adsorp- 

 tion film at the crystal surface. 



Conditions in ore deposits appear to correspond very well with 

 those in the laboratory, for crystallization may be found accom- 

 panied by local evidence of linear thrust or not, according to the 

 magnitude and distribution of the opposing forces. Its failure is 

 most often manifest in comb structure, found in crevices whose 

 walls are each lined with tightly adhering crystals which either 

 interlock and extend quite across the crevice or grow together near 

 the central plane and mutually exclude further development. 

 Such comb structure is common in veins, but far from universal. 



TABLE VIII 



Same Plates, Block of Glass, and Conditions, except 

 that the 2 per cent gum arabic solution has 

 Been Saturated with Potassium Aluminium Sul- 



It may be inferred, further, that linear pressure plays a subordi- 

 nate part in much more complex occurrences. 



Messrs. Bruhns and Mecklenburg seem to have misunderstood 

 the last paragraph of our paper in which we called attention to the 

 fact that the linear force of growing crystals cannot be disposed of 

 as a mystery comparable to the growth of plant roots. It is a 

 sharply defined physical process open to quantitative experimental 

 investigation. It may not be fully understood, but it is no mystery. 



