CONTENTS XV 



PAGES 



of soils ; Influence of color upon the temperature of soils ; 

 Rate of movement of air through soils ; Rate of move- 

 ment of water through soils ; Separation of sand, silt, and 

 clay; Sedimentation of clay; Properties of rocks from 

 which soils are derived; Form and size of soil par- 

 ticles ; Pulverized rock particles ; Reaction of soils ; The 

 granulation of soils ; Absorption of gases by soils ; Acid 

 insoluble matter of soils ; Acid soluble matter of soils ; 

 Extraction of humus from soils ; Nitrogen in soils ; Test- 

 ing for nitrates ; Volatilization of ammonium salts ; Test- 

 ing for phosphoric acid ; Preparation of acid phosphate ; 

 Solubility of organic nitrogenous compounds in pepsin 

 solution ; Preparation of fertilizers ; Testing ashes ; Ex- 

 tracting water soluble materials from a commercial fertili- 

 zer; Influence of continuous cultivation and crop rotation 

 upon the properties of soil ; Summary of results with tests 

 of home soil. 



REVIEW QUESTIONS 327-339 



REFERENCES . . . . . . . . 340-344 



INDEX 345~35 



