WATER IN SOILS 



13 



mately the same size. Distilled water was then slowly ad- 

 ded to each to the point of apparent saturation. The humus 

 probably was not thoroughly saturated owing to the resist- 

 ance of the numerous capillary air spaces contained in the 

 organic matter. The dishes were placed in similar physical 

 conditions and the water allowed to evaporate from the soil, 

 in order to determine the daily rate of evaporation. After 

 continuing the process for several days the soils were again 

 dried in an oven under the same conditions as before except 

 that they were not pulverized. The experiment of evapora- 

 tion was now repeated, using the hard soils, with the excep- 

 tion that this time they were allowed to become air dry. The 

 first experiment was performed in the laboratory under dry 

 conditions, the second under more moist conditions in the 

 plant house. The following tables give the data obtained : 



Water Capacity of Soils (in per cent of weight) 



Shrinkage of Loose Sails on Becoming Hard as Indicated by the 

 Difference in Bulk. 



