B. A. Keen 415 



free water is suggestive in any consideration of the "optiniiini-moisture- 

 content," and tlie passage, according to Cameron and Gallagher, of 

 various physical properties through a maximum or minimum value at 

 that point. 



(5) The same general conclusions on the relations existing between 

 the soil and its moisture content that were drawn from the writer's 

 experiments on the evaporation of water from soil, follow again. The 

 soil colloids must be considered as primarily concerned in the relations; 

 the water present is subjected to the same law over the whole experi- 

 mental range and the various constant and critical points shown by 

 soil at varying degrees of water contents, are approximate equilibrium 

 values only and do not indicate any break or abrupt change in the 

 physical condition of the soil moisture. 



{Received 1st June, 1919.) 



