PRACTICE XXX 



-134- 



#r 



FIG. 8 



A, lower section ; B, second section 



showing joint ; C, perforated bottom 



of A 



DETERMINATION OF PER CENT OF 

 CAPILLARY WATER AT DIFFERENT 

 HEIGHTS ABOVE THE WATER TABLE 



Students may be assigned to work 

 in groups, using the stock soils. 



Place a disk of cheesecloth in bot- 

 tom of tube. 



Fill a brass tube cut in 4- or 6-inch 

 sections, according to the accompany- 

 ing cut, with the soil to be studied. 

 Compact by letting the filled tube 

 drop a distance of 4 inches four times 

 on a book with covers removed. Place 

 the base in a pan of water and allow 

 the water to rise by capillarity. 



When the water has reached the 

 surface take the tube apart and place 

 the soil from each section in a weighed 

 pan. Set out to dry at room tempera- 

 ture for 24 hours. Place in an oven 

 for 24 hours. Cool partially and 

 weigh. 



On the basis of the water-free soil 

 calculate the percentage of total 

 water held, and by deducting the 

 percentage of hygroscopic water find 

 the actual percentage of capillary 

 water held. Find also pounds per 

 cubic foot and acre inches held in 

 each section. 



Why is there any difference in the 

 amount of water held at different dis- 

 tances above the water table ? 



REFERENCES. 



"Soils," Lyon and Fippin, pp. 148- 



149. 

 "Physical Properties of Soil," War- 



ington, pp. 77-79. 

 " The Soil," King, p. 157. 

 Soils," Hilgard, pp. 207-208. 



62 



