178 



Physics of the Soil. 



Table showing the absorptive power of soils spread out in thin 



layers. 



It will be seen that in the saturated atmosphere the 

 largest amount of moisture was absorbed at the highest 

 temperature, while the reverse was true in the half sat- 

 urated atmosphere. Under the high temperature the rate 

 of molecular movement is so rapid that the rate at which 

 the water from the air falls upon and enters the soil is so 

 much increased that more water must have accumulated 

 in the soil before the number of molecules which can 

 leave its surface in a unit of time equals that which falls 

 upon it. In the dryer atmosphere, on the other hand, 

 where there are less molecules to fall upon the soil and 

 increase its amount, the higher temperature favors the 

 rapid escape as much as when the saturation was high 

 and, since less water is condensing, a lower per cent, is 

 finally present when an equilibrium of interchange has 

 been reached. 



