294 ILLINOIS STATE ACADEMY OF SCIENCE 



3. The Veitch and Jones methods gave consistently 

 higher results than the Hopkins, particularly on those 

 soil types which ordinarily contain fairly large propor- 

 tions of colloidal material, including organic and inor- 

 ganic. 



4. The comparatively low results obtained by the Hop- 

 kins method are due probably to the failure of this 

 method to measure fully the absorption capacity of soils 

 for bases. 



5. The Comber and Truog field tests agreed fairly 

 closely with each other in the comparative intensity of 

 their respective colors with the various soils, but these 

 graduations of color intensity are considered of but little 

 significance as quantitative indications of the lime needs 

 of soils. 



6. Both the Comber and Truog tests are reliable as 

 qualitative tests. 



7. In the Comber test the alcoholic KCNS solution 

 must be brought in contact with the soil mass. Neither 

 water nor alcohol extracted ferric iron from the acid 

 soils used in these tests. 



8. By the addition of iron filings to the soil previous 

 to applying the Comber test, it may be used for soils very 

 high in organic matter, such as peats and peaty loams. 



ABBREVIATED LIST OF REFERENCES. 



1. Comber, N. M. Jour. Agr. Sci. 10, 420 (1920). 



2. Christenson, H. R. Soil Sci. -'/, 115 (1917). 



3. Carr, R. H. Jour. Ind. and Eng. Chem. 131. 



4. Conner, S. D., Abbott, J. B. and Smalley, H. R. Ind. Bull. 170. 



5. Hartwell and Pember, Soil Sci. 6, 259 (1918) 



6. Mirasol, J. J. Soil Sci, 10, 153 (1920). 



7. Troug, E. Jour. Ind. and Eng. Chem. 8, 341 (1916). 



8. Veitch, Jr. Am. Chem. Soc. 21,, 1120 (1902); 26, 637 (1904). 



