Bulletin 92, Bureau of Chemistry, U. S. Department of Agriculture. 



PLATE I. 



FIG. 1 ORTHOCLASE ROCK GROUND DRY IN A BALL MILL FOR THREE HOURS. 



FIG. 2. ORTHOCLASE ROCK GROUND WET IN 'A BALL MILL FOR THREE HOURS 

 (ENLARGED 25 DIAMETERS). 



