24 



Journal of Agricultural Research 



Vol. XII, No. I 



Table II. — Reaction of soil-film water 



o Sufficient soil not available for duplicate extractions. 



The data presented in Table II show rather conclusively that the 

 soil-film water has the same reaction as the free water. The difference 

 is only in degree of intensity. Those soils which showed an acid reaction 

 in suspensions gave a greater concentration of H ions in the film water. 

 Conversely, those which indicated a greater OH-ion concentration than 

 H in suspension gave a greater intensity of OH ions in the solution. 

 These results are not in keeping with those of Sharp and Hoagland (12), 

 who found no appreciable change in H or OH ions in varying the pro- 

 portions of soil to water in making suspensions. 



With the freezing-point method for measuring the concentration of 

 the soil solution Bouyoucos and McCool (j) show that as the amount of 

 water decreases in an arithmetic progression the lowering of the freez- 

 ing point (increase in concentration) increases in a geometric progression. 

 This apparently is due to the rendering inactive of a portion of the water 

 in the soils, hence this water does not take part in dissolving the solutes 

 of the soil. That portion left free or tmcombined becomes highly charged 

 with soluble salts and gives phenomenal increases in the freezing-point 

 lowering. The same line of reasoning may be applied to the increase in 

 intensity of reaction of film water when compared to that of soil sus- 

 pensions. 



With the heavier types of soil only a small percentage of the added 

 water was recovered. It would be of extreme interest to note the 

 intensity of reaction of the thinnest moisture film which could remain 

 in contact with the soil grains. In other words, all of the liquid added 

 to the soil should be recovered and studied. 



