PROPERTIES AND CONDITIONS OF SOIL 285 



Fill the lamp chimneys once more with the different 

 kinds of dry soil. Stand them in a dish or pan of water so 

 that the mouth over which the cheese cloth is tied will rest 

 about half an inch in the water. What happens ? What 

 makes the water creep upward in the soils ? 



Hang a towel over a desk so that about an inch of the 

 corner will rest in a dish of water sitting on the floor. 

 What takes place? The same thing is happening in the 

 towel and in the soil. The water is slowly rising. This 

 is due to what is known as capillarity or capillary attrac- 

 tion. To explain fully why this takes place would take us 

 too far into the subject of physics. It is enough for us to 

 know that liquids rise long distances through small tubes 

 or pores. We have a good illustration of this in the ordi- 

 nary lamp wick which conveys oil from the bowl of the 

 lamp to the top of the wick. 



In which kind of soil does the water rise most rapidly ? 

 In which does it reach the greatest height ? If a field has 

 an abundance of water in the subsoil this may be lifted by 

 capillarity to the place where it will be of use to the growing 

 plants. What becomes of this water as it reaches the sur- 

 face of the ground ? May much of it be lost to the plants 

 by evaporation? Is there anything that may be done to 

 prevent this waste of moisture during the dry, summer 

 months ? We saw that a layer of fine, dry soil on the moist 

 soil in the tumblers retarded evaporation. Now place in 

 two tin pails (lard or syrup pails will serve the purpose) 

 equal amounts of moist soil. Firm the soil slightly by 

 jarring the pails. Set them side by side. Leave one un- 

 disturbed, but in the other stir thoroughly the upper two 

 inches of soil every day. Weigh at the end of a week. 



