PRACTICE XI (Continued) 



The apparent specific gravity of soils varies with the degree 

 of compaction. Ar freshly plowed field is much lighter per cubic 

 foot than one compacted by rains, tramping, or by means of the 

 roller. 



Fig. 3. Soil Compactor 



A, movable interior to be lifted, which, by dropping, compacts the soil ; B, soil tube 

 in place on base of ^ ; C, rubber stopper closing tube ; D, felt or rubber cushion 



Why is the apparent specific gravity of a sandy soil higher 

 than that of a silt loam ? 



Why is the apparent specific gravity of peat so low ? 



24 



