412 Soil, Soil Solution ami Freezing-Point Determinations 



conceive of any physical reason why the amount of unfree moisture 

 actually increases and then decreases as the total moisture content 

 diminishes. For this reason it would seem more probable that the real 

 relation is expressed by a curve of the shape given when Fji is put 

 equal to 9, in which case, both !'„ and Z„ decrease in actual numerical 

 value as the soil gets drier, while the percentage ratio they bear to 

 the total moisture content decreases and increases respectively. An 



16 



20 



22 



2 4 6 8 10 12 14 



Amount of free water ( l'„) 



Fig. 4. Relation between free and unfree water, for various values of I'oi. 



examination of the numerical values for this curve shows that at low 

 percentages nearly all the water is present in the unfree condition. At 

 a total moisture content of 7, only -58 is free and 6-48 is rendered unfree. 

 The question as to whether this very small amount of free water would 

 make it impossible for the freezing-point depression to be measured is 

 partially answered by the experiments with quartz sand where a 

 moisture content of -7 per cent, gave satisfactory measurements. 



