6 Jackson and Rich, Solubility of Lead Glasses. 



These numbers when plotted as curves appear as in 

 the accompanying Figure. 



20 30 ■'O 50 60 70 80 '30 



Height in Piezoineler ( cms. ). 



Now since the finest material is carried over by the 

 slowest current of water, or when the water is at the least 

 height in the piezometer, it is clear from the above results 

 that there exists an undoubted connection between the 

 amount of surface exposed to the solvent, and the solu- 

 bility. At first sight it might appear that the solubility 

 should vary directly as the original surface of the particles ; 

 but our numbers do not support this conjecture. This 

 we consider can be explained by the hypothesis that the 

 action is more complex than a mere surface action of the 

 acid on the fritt, i.e., that by the friction of the particles, 

 during the hour's shaking, fresh surfaces are to some 

 extent exposed to action and so more material is dissolved 

 than is demanded by the simpler supposition of surface 

 action only. 



Having found that solubility in dilute acid is greatly 



