EXERCISE 8 

 THE RISE OF CAPILLARY WATER IN SOILS 



Object. To compare the rate of the rise of capillary 

 water in soils of different texture. 



Explanation. Capillary water is held in the soil as a 

 thin film surrounding the soil particles. It moves by the 

 force of capillarity from a moist to a drier part of the soil. 

 Capillary water will move upward through the soil if the 

 soil above is drier than the soil below. The height to which 

 capillary water will rise in the soil depends upon the soil 

 texture. In a coarse-grained soil it rises very rapidly, but 

 for only a short distance. In a fine-grained soil it rises 

 slowly, but to a greater height. Capillary water rises in the 

 soil until the force of capillarity is overcome by the force 

 of gravity. 



Equipment. 1. Four glass tubes 3 feet long and 1 

 inch in diameter. 



2. A tube rack for holding the tubes. 



3. A pan for water in which to immerse the bottom of 

 the tubes. 



4. Cheesecloth. 



5. String. 



6. One-foot rule. 



7. Air-dry soil : gravel, sand, loam, and clay. 



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