EXPERIMENT STATION BULLETINS. 503 



a sieve and theu mixed tlioronglilv. It was then placed in the tubes and 

 packed uniformly by allowing the tubes to fall in a vertical position from 

 a certain height a definite number of times. 



At the end of each experiment the warm column was separated from 

 the cold column of soil by means of a spatula. This was done by draw- 

 ing out all the soil from that warm section of the tube which extended up 

 to the plane of the partition and allowing for the cold column of soil 

 all the soil that was contained in that cold section of the tube up to the 

 other plane of the partition, and also that portion of the soil contained 

 in the tube under the hole of the partition. This last part of the soil was 

 accorded to the cold column of soil because its temperature is inter- 

 mediate between the opposite temperature extremes and it was desired 

 to make the lines of demarcation between the two columns of soil as 

 prominent and distinct as possible. The moist soils were dried in an 

 electrical oven for about 20 hours at a temperature of 105° C, and the 

 percentage of moisture content was calculated on the dry basis. The 

 weights were alwaj^s made on a sensitive chemical balance. 



The fact has been mentioned that the mobility of moisture from warm 

 to cold column of soil was studied in two different ways: (1) when the 

 column of soil stood horizontally, and (2) Avhen it stood vertically. The 

 data obtained from both series of experiments show that if the same per- 

 centages of moisture were employed practically the same results were 

 obtained, no matter whether the soil columns remained in the horizontal 

 or vertical position. For sake of brevity and simplicity of presentation, 

 therefore, only the results of the series of experiments wherein the soil 

 column was held in the vertical position, will be presented here. These 

 experimental data together Avith their diagramatic representations are 

 submitted below. Table 2 contains the different soils with their various 

 moisture contents, and the percentage of moisture moved from the column 

 of soil at 20° to the column of soil at 0° C. and from the column oC 

 soil at 40° to the column of soil at 0° C. The percentage of moisture 

 moved represents the difference between the percentages of moisture 

 found in the cold and warm columns of soil respectively at the end of 

 the experiment ; at the beginning of the experiment the moisture content 

 was the same in both columns of soil. Figure 2 represents all these data 

 in a graphical form. 



The foregoing data present many important and remarkable facts. 

 First of all, they show most emphatically that the a priori prediction re- 

 garding the thennal movement of moisture as deduced from the laws of 

 surface tension and viscosity in their relation to temperature, is not 

 strictly realized. According to these laws the amount of water moved 

 from warm to cold column of soil should be the same for all moisture 

 contents, providing the soil mass exerts no influence upon water; in- 

 asmuch, hoAvever, as the soil does exert an adhesive force for water, then 

 the thermal translocation of moisture should increase with rise in water 

 content. Instead, the percentage of tvatcr moved from warm to cold col- 

 umn of soil, at hoth temperature amplitudes, increases regularly and 

 rapidly icitJi increase in moisture content in all the different types of 

 soil, nntil a certain moisture content is reached and then it commences 

 to decrease with further rise in percentage of tvater. The results plot then 

 into a parahola, ivith a maximum point, instead of a straight line. This 

 maximum point of water thermal translocation is significanl iu at least 



