66 



THE PHYSICAL PROPERTIES OF SOILS 



increase in weight deducted from the total increase 

 in the soil trays. 



CONSTANT TEMPERATURE CHAMBER 

 Used in determining the hygroscopic capacity of soil. Heat is sup- 

 plied by means of a coil of fine wire attached to the lighting circuit 

 and coiled around the inner chamber. An air thermometer regulates 

 the temperature automatically. 



Tabulate the results and express the absorptive 

 capacity of each soil in per cent and as pounds per 

 acre-foot. 



How is the absorptive capacity effected by the tex- 

 ture of the soil and by the presence of organic matter? 



References : 



Hall, "The Soil," p. 8i. 

 King, ''The Soil," p. 252. 



