EXPERIMENT STATION BULLETINS. 571 



Table 6. Lowering of the Freezing Point of Various Types of Soils at Different Moisture Contents. 



Considering first Table 4 which contains the results of the quartz sand 

 it will be seen that by multiplying the percentage of moisture by its 

 corresponding depression a constant or factor is obtained which is re- 

 markably the same for all percentages of water content. These results 

 of the quartz sand, therefore, follow the mathematical law of inverse 

 proportionately and confirm entirely the results and conclusions of the 

 first investigation. 



It should also be recorded that a similar constant is obtained even 

 when the quartz sand is treated with a salt solution, allowed to dry, and 

 then its depression determined at different moisture contents. 



Examining next Table 5 which contains the typical datat obtained in 

 soils, it will be at once observed that these results are entirely different 

 from those of the previous table. In the first place they do not follow 

 the inverse proportionality law but the geometric progression law, that 

 is, the lowering of the freezing point increases in a geometric progres- 

 sion as the water content decreases in an arithmetic progression. The 

 closeness with which the results follow this law can be judged by compar- 

 ing the observed and calculated depressions. The calculated values were 

 obtained by dividing the last observed depression in each soil by the one 

 preceding and then multiplying the various observed depressions by the 

 ratio or constant thus obtained, A comparison of the two columns 

 immediately shows that the calculated values agree quite closely with 

 the observed ones. This close agreement is really remarkable considering 

 the nature of the soil medium. Those cases where the disagreement is 



