PRACTICE II 



DETER'MJNATION OF HYGROSCOPIC MOISTURE IN SOILS 



Use air-dry soils from Practice I after grinding thoroughly 

 m a mortar. 



Weigh the necessary weighing bottles or crucibles which have 

 been made water-free by drying in an oven at 100° C. for five 

 hours. Crucibles may be made water-free in a blast flame. Cool 

 in a desiccator before weighmg. It is best to weigh out all of 

 the duplicate samples at the same time, so as to have them 

 under the same moisture conditions: The hygroscopic moisture 

 of soil varies with the temperature and relative humidity of 

 the atmosphere. 



Dry in an oven at 100° to 105° C. for at least eight hours. 

 Cool in a desiccator. Weigh rapidly to avoid the absorption of 

 much moisture from the air. The loss in weight is the hygro- 

 scopic moisture. Express in tabular form on the opposite page 

 the hygroscopic water in grams and in per cent of water-free 

 soil; also the total moisture in the samples in per cent of 

 water-free soil. 



References. 



''Soils," Lyon and Fippin, pp. 141-144. 



;^The Soil," Hall, A. I)., pp. 84-88. 



" Physical Properties of Soil," Warington, Robt., pp. 57-60. 



"The Soil," King, F. IL, p. 252. 



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