SOIL WATER 



325 



sagebrush, and mesquite, can grow only where the supply 

 of moisture is very scant. Most cultivated crops cannot 

 live in a soil that holds too much free water ; that is, water 

 that lies between the particles of the soil instead of in a film 

 around them. Too much free water excludes the air from 

 the ground and the plant literally drowns. Even where 

 there is not sufficient free water to drown the plant, in- 

 sufficient under-drainage keeps the soil cold and prevents 

 the injurious substances in solution from being washed out 

 of the soil. This explains why flowerpots always have a 

 drainage-hole and why farmers are some- 

 times compelled to tile their farms. 



Experiment 96. Place small glass tubes 

 of several different bores in a dish of colored 

 water. In which is the surface of the water 

 higher, in the tubes or in the dish ? In which 

 tubes is it the higher, those of large or small 

 bore? 



Experiment 97. Place two wide-mouth 4-oz. bottles side by side 

 and fill one partly full of water. Put a coarse piece of cloth, or 

 better, a lamp wick, into the water bottle and allow the other end 

 to hang over into the empty bottle. (Figure 95.) Allow the bot- 

 tles to stand thus for an hour. 

 What happens? The force that 

 causes the rising of water up tubes 

 and wicks is called capillarity. 



Experiment 98. Tie pieces of 

 cloth over the ends of four lamp 

 chimneys. Fill one of the chimneys 

 with coarse sand, another with fine 

 sand, another with clay, and the 

 fourth with a deep black loam. Stand each chimney in a shallow pan 

 of water. (Figure 96.) Allow them to remain for a week, keeping 

 water in the pan all the time. Note how high the water has risen 

 in the different chimneys at the end of an hour ; two days ; a week. 



FIGURE 95 



FIGURE 96 



