EXPERIMENT STATION BULLETINS. 5G3 



EXPERIMENTAL DATA. (a) 



THE FREEZING-POINT LOWERING OF SOILS AT LOW AND HIGH MOISTURE 



CONTENT. 



In accordance with the foregoing improved method the freezing-point 

 lowering of a great number of soils was determined. These soils varied 

 greatly both in type and origin. They were obtained from ten different 

 states and were supposed to represent the typical types of these respec- 

 tive states. In these states are included California, Washington, Wis- 

 consin, Minnesota, Michigan, Kentucky, Texas, Florida, Ehode Island, 

 and Pennsylvania (5). From many of these states nearly all the main 

 and important types existing in them were emploj'ed in this investiga- 

 tion. In all 58 soils were used. The object of procuring soils from the 

 different states was to ascertain the magnitude of their freezing-point 

 depression and hence the concentration of their soil solution. The cul- 

 tural history of many of these soils is known for several years back and 

 therefore a comparison between the concentration of their solution and 

 their cultural treatment can be made. 



All these soils were used in the air dry state. Their freezing point 

 depression was determined at two different moisture contents, low and 

 high. The object for employing these two opposite and extreme water 

 contents was to ascertain the variation in the depression. The low mois- 

 ture content represents very nearly the minimum water content at which 

 solidification starts very readily and the results can be relied upon. 

 These low water contents were selected from a large number tried in each 

 soil. It must be emphasized, however, that they do not represent in 

 every case the exact point where solidification started readily, but only 

 approximately. 



The high moisture content may be taken to represent the point of 

 saturation. At this degree of water content the absorptive power of the 

 soil for water is quite satisfied. The addition of more water above this 

 point remains as gravitational water. 



The magnitude of the freezing-point lowering of the various soils ob- 

 tained at the two opposite moisture contents is shown in Table 3. The 

 percentage of water is expressed on the oven-dry basis. 



In the same table there are given the magnitude of concentration and 

 osmotic pressure that the depression of each soil at both moisture con- 

 tents represents. The concentration is expressed in parts per million of 

 solid material in one million parts of solution and was calculated directly 

 from soil water extracts and not from any particular pure chemical com- 

 pound or a combination therefrom. The procedure of accomplishing this 

 consisted of mixing 100 grams of soil with 500 c. c. of pure distilled 

 water, allowing the mixture to stand for about two days with occasional 



(a) The authors wish to express their gratitude and indebtedness to Mr. M. Wolkoff, a former grad- 

 uate student, for his aid in procuring some of the experimental data. 



(5) In procuring these soils from other states the writers are thankful and indebted to Prof. A. Whitson 

 of Wisconsin Agricultural College, Prof. Chas. Shaw of California Agricultural College, Prof. G. 

 Roberts of Kentucky Agricultural College, Prof. G. S. Fraps of Texas Agricultural College, Prof. W. 

 C. Etheridge of Florida Agricultural College, Prof. S. Severance of Washington Agricultural College, 

 Prof. F. Alway of Minnesota Agricultural College, Prof. White of Pennsylvania Agricultural College, 

 and Prof. Pember of Rhode Island Experiment Station. 



