MancJiester Memoirs, Vol. xlv. (1901), No. 15. 3 



upon the extent of surface exposed— that is, upon the 

 fineness of the particles. 



The following specimens of fritts were all reduced to 

 nearly impalpable powder in an agate mortar before being 

 submitted to the action of the solvent. They were there- 

 fore in closely similar, if not identical, conditions of 

 fineness. Hence, if the solubility were merely a function 

 of the extent of surface, the solubilities should all approxi- 

 mate to the same value. If subdivision were even a 

 considerable factor, there should be some approach to 

 similarity in the results— they should be quantities of 

 much the same order of magnitude. It will be seen that 

 there is no suggestion of any such uniformity : — 



Thus the fineness alone of a fritt is not the chief 

 factor in determining the solubility of the lead. The last 

 three specimens belong, in fact, to a class of silicates 

 which, whether ground moderately fine or extremely so, 

 readily give up practically the whole of their lead to 

 dilute acids. The first three belong to a class which, 



