722 



STATP] BOARD OF AGKICULTURPl 



TABLE 27.— RATE AND EXTENT OF SOLUBILITY OP NATURAL SOILS IN DISTILLED 

 WATER WHEN THE RATIO OP SOIIiS TO WATER IS 1 TO 5 AND THE MIXTURE 

 MAINTAINED AT THE TEMPERATURE OP 53°. FIGURES REPRESENT FREEZING 

 POINT DEPRESSION. 



1 



4 



8 



9 



11 



12 



14 

 19 

 31 

 26 



Days. 



Wisconsin Superior clay 



Georgia Cecil clay 



Michigan clay loam 



Michigan clay loam 



Michigan dark brown silt loam. . . 

 Michigan dark brown silt loam . . 

 Michigan dark orown silt loam. . 



Wisconsin Miami silt loam 



Mississippi Memphis silt loam . . . 



Michigan fine sandy loam 



California Okley fine sandy loam. 

 Michigan fine sand 



63 



C° 



.021 



.014 



.023 



.031 



.031 



.031 



.020 



.028 



.014 



.020 



.011 



.009 



A critical examination of the results in the above table and of those 

 in table 24 makes it at once apparent that even at the temperature of 

 53 °C the solubility of the soils, when the ratio of soil to water is 1 to 5, 

 is greatly less than that at the ratio of 1 to .7. Indeed, the degree of 

 solubility in many soils is only one-third as great in the ratio of 1 to 5 

 as it is in the ratio of 1 to .7. Thus, the freezing point depression at the 

 end of 63 days, was as follows for the various corresponding soils : 



Eatio — 



1:5 .021° .014° .023° .031° .031° .031° .028° .014° .020° .011° .009° C. 

 Ratio — 



1:7 .031° .011° .054° .068° .070° .064° .038° .019° .052° .013° .010° C. 



It is to be noted even at this high temperature that although the con- 

 centration is greatly lower at the ratio of 1 to 5 than it is at the 

 rate of 1 to .7 yet an a^jparent equilibrium sets in at the end of about 30 

 days and practically no material goes into solution thereafter. It would 

 be expected that the solubility at the ratio of 1 to 5 would continue much 

 longer and its extent would tend to reach that of th'e 1 to .7 ratio, but 

 such is not the case. 



It is extremely interesting to observe that the solubility product of 

 Cecil Clay and Memphis silt loam is extremely low and is not affected 

 either by temperature or water content, but remains constant under all 

 these treatments. In these respects, it acts very mucli like the solu- 

 bility product of pure sand and quartz sand. This is a very significant 

 fact. 



The results of all the preceding series of investigations go to prove 

 very conclusively at least one principle, namely, that when the solu- 

 bility of a soil becomes constant or stationary it does not mean that 

 absolute equilibrium has been attained or that the solution has become 

 saturated. This conclusion becomes at once obvious from the fact that 



