18 



EFFECT OF WATER ON ROCK POWDERS. 



TABLE II. White china clay, 

 SERIES I: CLAY DIGESTED 5 MINUTES. 



a Within limit of experimental error. 



The results which are given in Table II show conclusively that the 

 action which takes place is rapid, as the series in which the clay was 

 digested for three days is in essential agreement with the series in 

 which the digestion lasted for a few minutes. An inspection of the 

 tabulated results shows that the acid ions have not in any case been 

 absorbed. The quantitative results which show the amount of absorp- 

 tion of the bases have been very carefully checked and can be accepted 

 as practically constant for this clay with the solutions used. It is cer- 

 tain, however, that the figures must not be taken as indicating a defi- 

 nite absorption law. The barium was absorbed to a much higher 

 degree than the aluminum, but it must be remembered that the barium 

 chlorid solution was quite neutral, whereas it is not possible to pre- 

 pare a solution of an aluminum salt of an inorganic acid that does not 

 suffer hydrolysis and become strong^ acid. Moreover, barium is not 

 present in any form in the clay, whereas aluminum is its principal 

 basic 4 constituent. Undoubtedly these absorptions must be studied 

 from the point of view of the phase law and offer an attractive and 

 important field for research. 



In view of the fact that the alkaline constituents of rock powders 

 are to a certain extent set free by the action of water, while at the 

 same time pectoid matter is formed, it is interesting to study the 

 subsequent action of dilute solutions of ammonic chlorid in order to 

 determine whether the alkaline bases can be made to pass freely 

 into solution, as was found to be the case with colloidal precipitates. 



