88 THE rilYSlCAL PROPERTIES OF SOILS 



the same length of time. Again decant, and continue 

 the process until the water becomes clear. Evaporate 

 the liquid in the saucepan almost to dryness on a hot 

 plate, and transfer the residue to a weighed porcelain 

 dish. Complete the evaporation on a steam bath and 

 dry in the oven, cool in a desiccator and weigh. This 

 weight, less the weight of the dish, gives the amount 

 of clay which should be expressed as per cent of the 

 dry weight of the soil. 



SILT SEPARATIONS 



Stir up the soil remaining in the centrifugal tube 

 and allow to stand for about one minute, or until all 

 particles larger than silt (0.05) have settled. Decant 

 the liquid into a saucepan, stir the remaining soil in 

 the tube, and decant as before. Continue decanting 

 at the proper time until the water is again clear. 

 Evaporate the liquid in the saucepan as before, trans- 

 fer the residue to a porcelain dish, dry, weigh, and 

 calculate as in case of the clay. 



SAND SEPARATIONS 



Wash the sand remaining in the centrifugal tube into 

 a porcelain dish, evaporate on the steam bath, dry in 

 the oven, and weigh. This weight, less the weight of 

 the dish, represents the total sands. Sift this sand 

 through a nest of sieves provided for the purpose. 

 The material remaining in the first sieve is the fine 

 gravel ; in the second, coarse sand ; in tlic third, medium 

 sand; in the fourth, fine sand; and in the fifth, very 

 fine sand. Carefully transfer each grade of sand sep- 

 arately from the sieve to a dish and weigh. 



Calculate the i)cr cent of each grade, and tabulate 



