JoLY — Some Sedimentation Experiments and Theories. 



395 



TABLE II. 



Rate of Compacting. — Influence of Valency. 



5 Grammes Slate Powder in 12 c.cs. Zdquid. 



The following experiments, Table III., show the difference in behaviour for 

 sea water and fresh water ; the latter obtained from the city supply. Four 

 grammes of slate were used and 10 c.cs. of liquid. The numbers are the 

 depression of the surface of sediment in cms. below meniscus of liquid. It will 

 be seen that in the fresh water suspension no surface was discoverable. 



During the experiment a dark layer appeared rising in the bottom of the 

 fresh water suspension due to the coarser particles collecting below. 



In all these experiments care was taken to render the experiments strictly 

 comparative by mounting the tubes in groups close together upon the one stand 



