180 Physics of the Soil. 



have been replaced by an equal amount through condensa- 

 tion from some other place. 



It appears to the writer possible that the ability of such 

 soils to withstand drought may perhaps be partly due to 

 a more rapid evaporation from the soil grains and con- 

 densation of moisture on the root hairs, the thermal move- 

 ment, in this way, tending to supplement the enfeebled 

 capillarity. 



