720 EXPERIMENT STATION EECORD. [Vol. 36 



bulb is allowed to remain in the ice mixture with frequent movement until 

 equilibrium is reached. The total rise of the ligroin in the stem is taken to 

 represent the total quantity of water that freezes in the soil. 



" It was found that not all of the water added to soils freezes. Some of it 

 fails to freeze, and the quantity that fails to freeze is different in the various 

 classes of soil. Under the empirical conditions of 25 gm. of aii--dry soil mixed 

 with 5 cc. of water, supercooled to 3° C. in a temperature of —4°, the quantity 

 that fails to freeze varies from 2 per cent in quartz sand to 80 per cent in 

 clay, of the 5 cc. of water added. It increases, therefore, from the simple and 

 noncolloidal types to the complex and colloidal types of soil. 



" In the case of colloidal soils the amount of water that fails to freeze de- 

 creases with the increase in supercooling, but in the case of noncolloidal soils 

 it remains the same. By increasing the degree of moisture content, the amount 

 of water that fails to freeze is decreased in the colloidal soils, but remains prac- 

 tically the same in the noncolloidal soils. At the low-moisture content, suc- 

 cessive freezings diminish the quantity of the unfrozen water in the case of 

 the colloidal soils, but not in the noncolloidal soils. 



" The percentage of water content that fails to freeze in all soils under the 

 empirical conditions [stated] corresponds remarkably closely to the moisture 

 content known as the wilting coefficient, to the percentage of moisture at which 

 solidification can not be started, to the thetmal critical moisture content, 

 etc. . . . 



"The dilatometer method appears to be of considerable value in showing (1) 

 that soils cause water to become unfree, as indicated by its refusal to freeze ; 

 (2) in measuring quantitatively the amount of water thus becoming unfree; (3) 

 in determining, under certain empirical conditions, the wilting coefl^icient of 

 soils; and (4) in classifying, under certain empirical conditions, the water in 

 the soil into free, capillary, physically adsorbed, and chemically combined." 



The soil solution, how it is obtained, its composition and use in mechani- 

 cal analysis by sedimentation, J. P. van Zyx (Jour. Landw., 64 (1916), No. S, 

 pp. 201-275). — Experiments with a tenacious clay soil on methods of obtaining 

 the soil solution, and its composition and use in mechanical analysis, are 

 reported. 



It is concluded that methods hitherto used for obtaining soil solution, espe- 

 cially of heavy soil types, are either not permissible or are impracticable. The 

 pressing out of soil (Auspressen) was found to be a good method for obtaining 

 relatively large amounts of soil solution, especially from naturally very damp 

 soil. The concentration of the soil solution was found to vary considerably not 

 only for different soils but for different samples of soil from the same field. 

 The variations in different soils were due for the most part to fertilization and 

 climatic factors. The percentage composition of the soil solution in a heavy 

 clay soil, on the other hand, remained approximately the same with different 

 fertilization, which is attributed to the strong absorptive power of the soil. 



Mechanical analysis with distilled water was found to be the best process 

 for determining the absolute mechanical composition of the soil. The sedi- 

 mentation process with soil solution was entirely different from that with dis- 

 tilled water. The influence of fertilization and time of year was marked, but 

 the final results were similar to those obtained with distilled water. 



It is concluded that the use of the soil solution will give a close indication 

 of the momentary structure of cultivated soil. 



Methods of mechanical study of soils, D. J. Hissink (Arch. Suikerindus. 

 Nederland. Indie, 2^ (1916), No. SI, pp. 1204-1217).— Se\era.l methods of 

 mechanical analysis of soils are discussed. 



