PRACTICE XV 



DETEJ^MINATION OF POROSITY (SECOND METHOD) 



Find what per cent the apparent specific gravity is of the real 

 specific gravity and subtract this from 100 per cent. The re- 

 mainder expresses the per cent of pore space in the soil, or its 

 porosity. 



Use the real specific gravity and the average figures for 

 apparent specific gravity from Practice XI, as given you by 

 the instructor. 



Determine the porosity of the stock soils, loose and compact, 

 and express the results in tabular form. 



What relation exists between porosity and apparent specific 

 gravity ? Why ? 



References. 



*\Soils," Lyon and Fippin, pp. 92-93. 

 " The Soil," Hall, pp. 60-63. 



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