EXPERIMENT STATION BULLETINS. 605 



From a careful examination and consideration of tlie above results 

 it will at once be recognized that they are extremely unusual and indeed 

 almost incredible, in view of the present ideas concerning the soil solu- 

 tion. They show, for example, that at the high moisture content, the 

 lowering of the freezing point and conwquently the concentration, are 

 very small and only slightly different for the various classes of soil, but 

 at the low moisture content, the lowering of the freezing point and con- 

 sequently also the concentration, are extraordinarily high and very differ- 

 ent for the same classes of soil as above. Thus, at the high water content, 

 the magnitude of the lowering of the freezing point varies from .003° C 

 in case" of the peat, to O.OoO°C in humus loam, but the mean for the 

 majority of the soils is around 0.010° and 0.020°C. At the low moisture 

 content, however, the magnitude of the depression varies from 0.070°C 

 in the case of washed quartz sand of medium texture, to 0.955° C in 

 medium heavy clay, and tends to increase" from soils composed mainly 

 of pure silica, to soils containing complex aluminum-silicates and or- 

 ganic matter. 



These values of the freezing point depression at the low moisture con- 

 tent would have been still greater had the moisture content been farther 

 lowered. It is to be noted. hoAvever, that with some soils, the lowering 

 of the freezing point could not be much more increased with further 

 reduction in water content because they have approached the point of 

 dryness. Thus, the quartz sand and one of the sandy soils contain only 

 1.5 and 2.6% of water, respectively. While many of the clays and clay 

 loams contain as much as 20% and one of the peats, 138.97% moisture. 

 Yet, when the quartz sand and sandy soils have reached the point of 

 dryness, their maximum lowering of the freezing point is only about 

 ().ioO°C, while that of the clays and clay loams, whose moisture content 

 is more than enough to saturate these sandy soils, give a lowering of 

 the freezing point close to 1.000°C, or ten times greater. 



The concentration that the lowering of the freezing point at the low 

 moisture content of the more complex soils represents, is really tre- 

 mendous. Thus, the depression of .935 °C in one of the clay soils repre- 

 .sents a concentration, as calculated by the method already described, of 

 28,940 p. p. m. and an osmotic pressure of 12.04 atmospheres. These 

 great magnitudes of concentration and osmotic pressure of clay are 

 typical examples of all the complex types of soils investigated. In the 

 simple types of soils. hoAvever, as typified by quartz sand, the corres- 

 ponding depression of .070°C indicates a concentration of only 2121 p. 

 p. m. and an osmotic pressure of 0.800 atmospheres. 



On the other hand, the concentration that the depression of the freez- 

 ing point of all the soils represents at the high moisture content, is 

 comparatively low, averaging about 600 p. p. m. for the majority of 

 the complex soils and about 300 p. p. m. for the simple soils, with an 

 osmotic pressure of .350 and .150 atmospheres, respectively. 



A further examination of Table 2 also reveals the remarkable fact 

 that the lowering of the freezing point increases in all the soils, with 

 the exception of quartz sand, at a far greater rate than the percentage 

 of water decreases. In other words, the ratio of the lowering of the 



