40 A UNIT IN AGRICULTURE 



tlic \vatrr in the tumbler l.rloiv and after the experiment. This- power 

 of soils to raise water from below is called capillarity, and the water 

 is called capillary water. Because of this capillarity, plants are able 

 to get moist n re from the subsoil in time of drought. What effect on 

 water capacity does the addition of organic matter have? (Jive one 

 method by which the farmer may increase the amount of organic mat- 

 ter in the soil. 



Wator that percolates through the soil until it reaches the rock 

 or hard pan is called soil water. How deep are the wells in your 

 neighborhood? Are they deeper on the upland than on the lowland? 

 Is the impervious layer rock or clay? Are there any springs? If so, 

 observe the character of the strata over which the water flows. 



Ex. 21. Absorption of Moisture from the Soil. 



Material : a wide mouthed bottle, an egg, a glass tube 3 or 4 

 inches long and about y inch in diameter, a candle and a piece of 

 wire about 5 inches long. 



Remove part of the shell, about the size of a dime, from the large 

 end of the egg, without breaking the skin beneath. In the same man- 

 ner remove a piece of shell, no larger than the diameter of the glass 

 tube, from the small end of the egg. Cut from the lower end of the 

 candle a piece about Vi> inch long and bore a hole in this the size of 

 the glass tube. Soften one end of the piece of candle and stick it on 

 the small end of the egg so that the hole in the candle covers the hole 

 in the egg, making a water-tight joint. Place the glass tube in the 

 hole in the candle, cement closely as before. Now run the wire down 

 the tube and break the skin of the egg. Now fill the bottle with 

 water until it overflows and set the egg over the mouth of the bottle, 

 small end up. In an hour or so, the white of the egg will be seen ris- 

 ing in the glass tube. The water enters the egg through the skin and 

 forces the white to rise in the tube. The skin itself has no openings 

 that can be seen even with a microscope. This process by which a 

 liquid passes through a membrane is called osmosis. It is by this 



