THE PHYSICAL ACTION OF LIME ON CLAY SOILS 



The recent investigations in the field of soil acidity have raised anew 

 the question of the physical action of lime on the soil. A number of 

 physical investigations have been conducted in the past, but the recent 

 progress in certain auxiliary subjects, as colloid chemistry, has tended 

 to depreciate the value of much of this work, and bring new problems 

 to the front. The question may therefore be properly considered again : 

 What is the specific effect of each form of lime on the soil, and how great 

 is that effect? 



Our problem resolves itself into two parts: First, the selection of 

 desirable methods, and second, their application. Let us first review the 

 procedures available for the study of the colloidal characteristics of the 

 .soil, and determine wherein their merits and deficiencies lie. The vari- 

 ous methods may be classified under eight distinct headings, as follows: 



Methods for Estimating Soil Colloidality 



Flocculation in solution. 



1. The suspension method. 

 Solubility of colloidal material. 



2. Fraps Ammonia Method. 



3. Van Bemmelen Acid Method. 



4. Endosmometer method. 

 Heat Liberation on Wetting. 



."). Poiiillet-Mitscherlich Method. 

 Capillarity and Eetentive Power. 



6. Hilgard Total Retentive Cup Method. 



7. Briggs and McLane Moisture Equivalent Method. 



8. Capillary Kise of Water. 



9. Percolation of Water. 



10. Atterberg Plasticity Method. 

 Adsorption. 



11. Hygroscopic Water. 



12. Dye Adsorption. 



13. Selective Adsorption of ions. 



14. Endell Histological Method. 

 Volume Change. 



15. Expansion Method. 



ACKNOWLEDGMENT 



The writ' r takes pleasure in ackiHovledging his obligations to Professors T. L. Lyon. W. 1). 

 Bancroft. T. I*. Briggs. and II. O. Buokman for helpful criticisms and suggestions He is 

 particularly ; ndebted to Professor J. A. Biz/oil, under The immediate di ection of whom the 



work was conducted. 



