204 PRACTICAL AGRICULTURE. 



It is also found that some soils retain water much 

 more strongly than others when exposed to a dry at- 

 mosphere. Thus, if you should moisten a handful of 

 dried sand, another handful of dried clay, and another 

 of dried peat, with equal portions of water, and ex- 

 pose them to a dry atmosphere, the sand will lose its 

 water two or three times as fast as the clay, and three 

 or four times as fast as the peat. 



CAPILLARY ATTRACTION. 



387. If you thrust one end of a small glass tube 

 into water, the water will rise inside of the tube higher 

 than its surface on the outside. It is drawn up by the 

 attraction of the glass, called capillary attraction. The 

 same takes place in a sponge, which is but a collection 

 of small tubes. If the lower part of the sponge 

 touches the surface of -the water, the water will be 

 drawn upward, and will fill the whole. So if a snow- 

 ball be brought into contact with water, the same will 

 take place. 



888. This capillary attraction exists in soils. If you 

 fill a cup with dry soil, after having made a hole in 

 the bottom of the cup, and then place it in a broad 

 dish containing a little water, the water will find its 

 way upward, till it moistens the whole soil, and ap- 

 pears on the surface, It is thus in the open field. 

 Water in the subsoil is drawn upward by capillary 

 attraction. If there is a surplus of water in the sub- 

 soil, it is drawij upward \n too great quantities. 



