CONTENTS. 



Page. 



Wet grinding 5 



Marked effect of water upon the binding power of certain substances 7 



Discussion of phenolphthalein reaction 9 



The colloid theory . 12 



Absorption power of clays and rock powders 16 



Practical applications 22 



Summary 23 



ILLUSTRATIONS. 



Page. 

 PLATE I. Fig. 1. Orthoclase ground dry in a ball mill for three hours. 



Fig. 2. Orthoclase ground wet in a ball mill for three hours 8 



^ II. Fig. 1. Orthoclase ground wet in an agate mill for three hours. 



Fig. 2. Wet ground orthoclase stained with methylene blue 8 



III. Fig. 1. Orthoclase dust in the finest state of subdivision possible. 



Fig. 2. Same powder as shown in fig. 1, ground wet, dried, and 

 repul verized 16 



IV. Fig. 1. Same powder as shown in Plate III, fig. 2, but stained with 



methylene blue. Fig. 2. Wet ground orthoclase powder remain- 

 ing in suspension in water after several days, dried, and lightly 



pulverized 16 



3 



