Date 



EXERCISE 21 (55) 



Capacity of Loose and Compact Soils to Hold Water 



Purpose. — To study the influence of the texture and structure of different 

 soils upon their capacity to retain water. 



Use four soils — sand, loam, clay, and muck. 



1. Select eight soil cj'linders (Fig. 16) and place a circular piece of filter 



paper in the bottom of each. Number and weigh each cylinder carefully. 



2. Fill the first four tubes to within exactly one inch of the top, pouring the 



soil in gentl}' so that it will rest in the tube in a very loose condition. 



3. Fill the second lot of tubes to within one inch of the top and pack uniformly 



by the dropping method or by means of the compacting machine. 



4. Weigh and record weights of filled tubes. 



5. Place the tubes in a galvanized iron tank and pour water around them 



until it reaches the height of the surface of the soil, thus allowing the 

 water to percolate up through. 



6. Let stand until moisture appears at surface of soil in each cylinder, noting 



time required for water to come up through. 



7. Finally remove the tubes from the tank and, after wiping off all free water 



with a cloth, weigh immediately upon balances. 



8. Place cylinders in racks where the water maj^ be allowed to percolate out, 



and cover top with a glass plate to prevent evaporation. 



9. Weigh the cylinders according to the time indicated in the table. 



