FORMS OF SOIL WATER 



plants, like rice, which grows part of the time with 

 its roots covered with free water. 



CAPILLARY WATER 



* 



If you will take a number of glass tubes of differ- 

 ent sizes, the largest not more than one-fourth of 

 an inch in diameter, and hold them with one end 

 of each in water or some colored liquid, you will 

 notice that the water rises in the tubes (Fig. 26), 

 and that it rises highest in the smallest tube. The 

 force which causes the water to rise in these tubes 

 is called the capillary force, from the old Latin 

 word capillum (a hair), because it is most marked 

 in hair-like tubes, the smaller the tube the higher 

 the water will rise. The water which rises in the 

 tubes is called capillary water. 



Another method of illustrating capillary water is 

 to tie or hold together two flat pieces of glass, keep- 

 ing two of the edges close together and separating 

 the opposite two about one-eighth of an inch with a 

 sliver of wood. Then set them in a plate of water 

 or colored liquid and notice how the water rises 

 between the pieces of glass, rising higher the smaller 

 the space (Fig. 27). It is the capillary force which 

 causes water to rise in a piece of cloth or paper 

 dipped in water. 



Take a plate and pour onto it a cone-shaped pile 

 of dry sand or fine soil; then pour water around 

 the base of the pile and note how the water is drawn 

 up into the soil by capillary force (Fig. 28). 

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