168 Conductivities and Viscosities in Pure and in Mixed Solvents. 



work, van Bemmelen 1 had shown that the treatment of a soil with a 

 solution of potassium chloride resulted in an almost complete exchange 

 of potassium for sodium, calcium, and magnesium. In one experiment 

 he determined the chlorine and found that the amount had not changed. 



Schreiner and Failyer 2 percolated a solution of potassium chloride 

 through a short column of clay soil at the rate of 50 c.c. in 24 hours. 

 The first few hundred cubic centimeters of the 200 parts per million 

 solution, in passing through the soil, was reduced in concentration to 

 approximately 60 parts per million of potassium. In the succeeding 

 fractional percolates the concentration gradually increased until it 

 reached 173 parts per million when 1,100 c.c. had passed. Up to this 

 point the soil had retained approximately 900 parts per million of 

 potassium. The absorption obtained with clay loam was less than 

 that observed in the clay, while loam soil gave results intermediate 

 between the clay and the clay loam. For the sandy loam used, the 

 absorption was much less marked than in the finer textured soils, but 

 was, nevertheless, quite marked in the first fractional filtrates. At 

 the close of the absorption periods the clay and the clay loam soils were 

 washed with distilled water, the percolation of water being at the 

 same rate as that used in passing the potassium solution. After about 

 450 c.c. of water had passed through the clay soil the successive frac- 

 tional percolates showed a practically constant composition of 20 parts 

 per 1,000,000 of potassium. The washing was continued until over 

 2 liters of water had passed, at which time the quantity of absorbed 

 potassium in the soil had been reduced to 350 parts per 1,000,000 from 

 an initial concentration of 900 parts. With the clay loam the removal 

 of the absorbed salt was more rapid. The quantity of potassium in 

 this soil was reduced from 570 to 250 parts per 1,000,000 with the 

 passing of approximately 800 c.c. of water. 



Patton and Waggaman 3 have recalculated the results of Peters's 4 

 work on the absorption of potassium chloride from aqueous solutions 

 by the soil. They bring out the fact that the absorptive effect is nearly 

 twice as great with dilute solutions as with the strong concentrations. 

 With his most dilute solution (1.011 grams of potassium per kilo of soil) 

 94 per cent of the total potassium present was absorbed, while from a 

 solution 20 times as strong only about 55 per cent was removed. 



In the same publication Patton and Waggaman call attention to the 

 fact that the maximum absorptive capacity of an absorbent, while a 

 perfectly definite quantity, is of little practical interest in soil studies, 

 because of the fact that maximum absorption can take place only in 

 the presence of a solution which is saturated with respect to the solute 

 and at the same time is in equilibrium with the absorbing material. 



!Landw. Vers.-Stat., Bd. 21, pp. 135-191 (1877). 



2 U. S. Dept. Agriculture, Bureau of Soils, Bui. 32 (1906). 



3 Ibid., Bui. 52, (1908). 



4 Landw., Vers.-Stat., 2, 129 (1860). 



