WHAT WATER DOES IN SOILS 



45 



surface evaporates quite as much as a water surface. 

 So, in the greater part of the arid states, it is easy to 

 lose the entire rainfall of the year unless we make it 

 penetrate the land by the means described above. 



Wick action of soils. Soils differ greatly, both in the 

 rapidity with which water rises in them by wick action, 

 and in the height to which 

 water finally rises in them 

 (figure 20) . In soils having 

 much coarse sand, water 

 will rise ten or fifteen 

 inches in a few hours or 

 days, and will then rise no 

 farther however long you 

 may leave it. Soils having 

 much fine, powdery silt 

 will draw up the water 

 more slowly, but after one 

 or two months, it will 

 stop at a height of four 

 or five feet. In some such soils water has been known 

 to rise twelve feet in eighteen months. In clay soils 

 water rises still more slowly, but may finally rise to 

 forty or fifty inches. 



The picture (figure 21) shows how such trials are 

 made. The glass tubes, or lamp chimneys, have a 

 piece of muslin tied around their lower ends, which dip 

 into water, which darkens the color of the soil as it rises. 



Sand 

 10 in. 



Clay 

 2^ in. 



FIG. 20. Three tubes filled with soil 

 and placed with the lower end in 

 water for two hours. The height 

 to which the water rose is shown 

 by the black part of each tube. 



