EXPERIMENT STATION BULLETINS. 579 



The question now is, in what particular form or forms does this in- 

 active or unavailable water exist in the soil? It should be mentioned 

 that this special subject is now under investigation and the final con- 

 clusions will be reserved for a subsequent paper. It might be mentioned 

 here, however, that this inactive or unavailable water appears to exist 

 both as physically adsorbed water and as loosely chemically combined 

 water with the latter probably predominating. In both cases the water 

 is conceived to exist practically in- a solid state like water of crystali- 

 aation. 



The foregoing hypothesis, therefore, would tend to explain, at least 

 partially, why the lowering of the freezing of soils, with the exception of 

 quartz sand and possibly of some extreme types of sand, should increase 

 in a geometric progression while the percentage of water decreases in 

 an arithmetic progression. It would also tend to explain why the 

 freezing-point lowering of the quartz sand should increase inversely pro- 

 portionally with the water content, which would tend to indicate that 

 quartz sand causes very little if any of the water added to become in- 

 active or unavailable. That the latter fact might be so is further shown 

 by the solidification which can be induced when the moisture content is 

 only 0.7% or practically at absolute dryness. Jt should be stated, how- 

 ever, that even quartz sand under certain conditions, may cause some of 

 the water to become inactive, the amount, however, is very small. 



THE SIGNIFICANCE OF THE INACTIVE OR UNFREB WATER IN THE SOIL UPON 

 VARIOUS DETERMINATIONS NOW IN VOGUE. 



If the soils cause some of the water to mecome inactive or unfree 

 and the amount varies with the kind of soil, then the results obtained by 

 some methods now in vogue are not really and justly comparable. Thus, 

 for instance, take the results obtained from soil water extracts as pre- 

 pared by mixing soil and water in certain definite proportions. If the 

 extracts are made from various types of soil .':'nd these types of soil 

 cause difi'erent amounts of water to become inactive or unfree and 

 thereby lose its solvent action, then the soils are really extracted not 

 by the same amounts of water but by entirely different quantities. The 

 result will be that the concentration of the extracts will vary not en- 

 tirely according to the total soluble material present but also accord- 

 ing to the amount of water which acted as a solvent. 



The validity and force of these statements are most strikingly illus- 

 trated by the data presented in Table 8. These data were obtained by 

 mixing 20 grams of air dry soil with 4 c. c. of water and then determin- 

 ing the lowering of the freezing point in the usual manner. This pro- 

 cedure is really and purposely an imitation of the method widely used 

 by mixing 100 grams of soil with 500 c. c. of water and then ascertain- 

 ing the concentration of the extract. 



