18 FIELD AND LABORATORY STUDIES OF SOILS 



the amount of water used. This represents the amount 

 of water necessary to fill all of the open space in the sand. 

 Repeat the above operations, using the sample of clay soil. 

 Report 3'our observations in the following table: 



Fig. 9. — Spring-board Compactor Used to Secure Uniform Packing 

 of the Soil. The can or tube of soil is placed at the middle of 

 the board and the weight on the standard to the left is dropped 

 a definite number of times from a fixed ))oint. 



Discussion: The large amount of water which a can 

 will hold after it is already filled with dry soil serves to 

 bring out the fact that only about half of the soil is occu- 



