52 



THE PHYSICAL PROPERTIES OF SOILS 



first week. After the first week the intervals may be 

 lengthened to three days. 



A short time before the end of the term make a close 

 comparison of the different tubes. Plot a curve show- 

 ing the height of the water at each observation. Dis- 

 cuss the effect of texture and the presence of organic 

 matter upon the capillary rise of moisture as shown 

 by the behavior of the soils in these tubes. 



How do these results compare with those obtained 

 in the preceding exercises ? 



References : 



Hilgard, "Soils," pp. 202-207. 



King, "Physics of Agriculture," pp. 161-165. 





TORSION BALANCR 



Used for all rough weighings. A chemical balance is used where 



greater accuracy is required 



