46 THE PHYSICAL PROPERTIES OF SOILS 



SEVENTH EXERCISE 



I. CAPILLARY RISE OF MOISTURE IN 



SOILS 



Prepare five brass capillary tubes (T) and fill them 

 as follows : 



Tube No. I — Sand. 



Tube No. 2 — Mixture, three parts sand, one 



part organic matter. 

 Tube No. 3 — Loam or silt. 

 Tube No, 4 — Clay. 

 Tube No. 5 — Mixture, three parts clay, one 



part organic matter. 



Compact each tube on the spring-board compactor 

 by dropping the weight four times from the lo-inch 

 mark, and weigh. Place the tubes in a rack with the 

 lower ends dipping into a tray of water, the depth of 

 the water being kept at a constant level by means of 

 a siphon flask. Record the height of the rise of water 

 after thirty minutes, one hour, and every twenty-four 

 hours thereafter for seven days. 



Express the results in tabular form and by means of 

 curves. Discuss the efifect of texture and the presence 

 of organic matter upon the capillary rise of moisture. 



References : 



Hall, "The Soil," pp. 68 and 94. 

 Hilgard, "Soils," pp. 202-208. 



II. INTERRUPTION OF THE CAPILLARY 

 RISE OF MOISTURE 



Fill three brass tubes (T) to the depth of one foot 

 with sandy loam soil, and place them in a rack with 



