LABORATORY PRACTICE 31$ 



filling one tube, and moderately compacting another with the com- 

 pacting machine- Note the difference in time required for the air 

 to pass through the loose and the compacted soil. 



FlG. 56. Aspirator for determining the Rate of Movement of Air through Soils. 

 (Adapted from Bui. 107, U. S. Dept. Agr., Office of Expt. Stations.) 



Experiment No. 9 

 Separation of Sand, Silt, and Clay 



For this experiment the student should use some of the soil from 

 his home farm. Ten grams of air-dried and crushed soil which have 



