44 THE PHYSICAL PROPERTIES OF SOILS 



pirator bottle, open the stop-cock, and note the time 

 necessary for one hter of water to escape. Repeat with 

 each of the soils, and tabulate the results in liters per 

 hour. Make at least two determinations on each soil. 

 What effect has the texture of the soil and the pres- 

 ence of organic matter upon the rate of aeration? 



II. FLOW OF AIR THROUGH FIELD 

 SOILS IN PLACE 



The permeability of undisturbed field soils may be 

 determined with this apparatus in the manner described 

 by King, ''Physics of Agriculture," p. 127. 



The movement of air in field soils in place may be 

 determined also by the Heinrich method, as described 

 by Wiley, ''Agricultural Analysis," Vol. I., pp. 

 163, 164. 



References : 



Burkett, "Soils," pp. 95-96. 

 King, "The Soil," p. 239. 

 Hilgard, "Soils," p. 279. 



