EXPERIMENT STATION BULLETINS. 629 



The lowering of the freezing point has been determined in a large 

 number of soils at two different moisture contents, low and high. The 

 results of this study show that at the high moisture content the freezing 

 point lowering of all the different types of soil examined is very low 

 and varies only slightly in the different soils. At the low moisture con- 

 tent, however, the lowering of the freezing point is very high and varies 

 tremendously with the extreme types of soil, being highest in clay type 

 and low^est in sand. The amount of concentration and osmotic pres- 

 sure that are represented by the great depressions in the complex types 

 of soil, are indeed very great. The depression of .955°C of clay, for in- 

 stance, which was obtained at 18.80% moisture content, represents a 

 concentration of 28,941 p. p. ni., and an osmotic pressure of 12.04 atmos- 

 pheres. 



In all the soils, with the exception of quartz sand and some extreme 

 types of sandy soil, the ratio of the lowering of the freezing point is 

 not directly inversely proportional to the ratio of the water content, as 

 might be expected, (approximately), but the former is many times 

 greater than the latter. Thus, in the case of clay the inverse ratio be- 

 tween the lowering of the freezing point and the water content is 27 

 to 1.85, respectively. Upon investigating this relation more thoroughly 

 by determining the lowering of the freezing point of various soils at 

 a large number of moisture contents it was found that this relation fol- 

 lows a mathematical law and indeed the geometric law, i. e., the lower- 

 ing of the freezing point increases in a geometric progression while 

 the water content decreases in an arithmetic progression. In the case 

 of quartz sand and some extreme types of sandy soil, however, the de- 

 pression of the freezing point increases inversely proportional with 

 the water content. 



The enormous concentration which the lowering of the freezing point 

 of some soils represents at the low moisture content created at first 

 some doubt as to whether this lowering of the freezing reall^y repre- 

 sents concentration or is caused by some physical factor such as the 

 supposed pressure with which the water films are held by the soil parti- 

 cles, etc. All possible physical factors that might enter into the freez- 

 ing point have been thoroughly considered but it has not become appar- 

 ent that the great depressions have been caused by any physical agent. 

 On the contrary all evidences, both direct and indirect, point over- 

 whelmingly to the fact that these high depressions of the freezing point 

 are produced by and represent actual concentration. Thus, washed 

 quartz sand which would not be expected to possess a solution of high 

 concentration causes a lowering of the freezing of only .070°C at 1.5% 

 moisture content, while clay, which would a priori be considered as 

 containing a solution of high concentration produces a depression of 

 the freezing point of .955°C at 18.80% moisture content. The rate of 

 increase in the lowering of the freezing point with the decrease in mois- 

 ture content is uniform throughout, from the maximum to the minimum 

 moisture content, etc. 



In explaining that the high depression of the freezing point at the 

 low moisture content, or the increase of the depression of the freezing 

 point with the decrease in moisture content, might represent concen- 



