316 EXPERIMENT STATION RECORD. [Vol.40 



periment Station it was found that when different kinds of soil were washed 

 until their soluble salt content was greatly reduced, their lowering of the freez- 

 ing point was practically identical. This suggested that at a comparatively 

 high moisture content the influence of the unfree water on the concentration of 

 the soil solution was practically negligible, If not entirely absent. It was 

 found further that air-drying did not increase the freezing-point depression of 

 the soils. On the basis of these facts, the following method to determine the 

 absolute salt content of soils at high moisture content was devised : 



" The soils are allowed to air-dry if freshly taken from the field. Then a 

 15-gm. sample of soil is taken and poured into the freezing tube containing 

 10 cc. of distilled water. The soil is stirred, usually by shaking, allowed to 

 stand for a few minutes, and its freezing-point depression determined. For 

 accomplishing the latter the tube is placed directly in the ice mixture, having 

 a temperature of about —2.5° C, and the soil Is stirred constantly with the 

 Beckmann thermometer until the temperature falls to about 1° above the zero 

 point of the thermometer. Then it is allowed to remain undisturbed until the 

 temperature falls to about 0.5° below the zero point, when the soil is again 

 stirred with the thermometer in order to cause solidification to take place. As 

 soon as solidification begins, the tube is at once taken out of the ice mixture 

 and placed in the air jacket in the same bath. The soil is gently stirred and 

 the thermometer gently tapped, and the freezing point read by means of a lens. 

 By this procedure it takes only about 10 minutes to make a freezing-point deter- 

 mination." 



Tests of the method which Indicate a high degree of accuracy are reported. 



Chemical estimation of the fertility of soils in Fulton County, Ind., EL H. 

 OABB and \Y. K. Cam {Proc. Ind. Acad, fifot, 1917, pp. 101-eiO, figs. 8).— The 

 results of determinations of total organic matter, nitrogen, and phosphorus in 

 128 soil samples, Including 38 subsoils and l ( o virgin soils, are presented and 

 a correlation of the data with the yield of corn per acre attempted, observa- 

 tions were also made upon the presence of carbonates and upon soil acidity. 



About one half the soils of the county were found to contain less than i per 

 i of organic matter. Six of the samples are described as unusually acid and 

 52 as slightly acid to litmus, most of the add -oils also being low in organic 

 matter. Both the nitrogen and phosphorus content of a large number of these 

 soils was less than 1,500 lbs. per acre (to a depth of 65 in.). The cultivated 

 soils showed a considerable decrease in plant-food elements as compared with 

 corresponding virgin soils. The results are held to Indicate that corn yields 

 increase with an increase of the nitrogen and phosphorus content of the soil. 



Granitic and gneiss soils of the Corso {Rev. Sri. [I'aris], 57 (1919), No. 1. 

 p. 26). — Brief reference is made to a recent monograph by D. Bollande on the 

 geology of the Corso, in which the character of the soils derived from gran. 

 and .umeiss. and the processes by which they are formed, are discussed. 



Soil acidity as affected by moisture conditions of the soil, S. D. Connkr 

 (Jour. Agr. Research [U. S.], 15 (WIS), No. 6, pp. 381-489).— Supplementing 

 previous Investigations at the Indiana Experiment Station on soils from tiled 

 and untiled land (E. S. K.. 40. p. 22 I, live typical acid Indiana soils were studied 

 under controlled moisture conditions in pots, namely, at full water-holding 

 capacity, at one-half water-holding capacity, and at one-fourth water-holding 

 capacity, other portions of each soil being taken when the pots were tilled and 

 kept in an air-dry condition in the laboratory. Samples of the soil of each pot 

 were tested for acidity by the potassium-nitrate, calcium acetate, and ethyl- 

 acetate methods in both moist and air-dried condition, and the potassium nitrate 

 extracts were analyzed. 



