xii CONTENTS 



Retention of Substances by Soil. 



PAGE 



46. Absorption of Colouring Matter and Free Ammonia . 68 



47. Absorption of Salts (Qualitative) . . . .68 



48. Absorption of Salts (Quantitative) . . .69 



49. Removal of Lime from the Soil . . . .71 



CHAPTER VII 

 Physical Properties of Soil 



Colour of Soil. 



50. Observation of Colour . . . . • 73 



Specific Gravity. 



51. Determination of True Specific Gravity . . .74 



52. Determination of Apparent Specific Gravity . . 74 



Pore-space. 



53. Direct Determination in Sand . . . .74 



54. Pore-space of Soils by Calculation . . •75 



Absorption of Water by Soils. 



55. Hygroscopic Moisture • • • • = 75 



56. Retention of Water by Soils . . . .76 



57. Percolation of Water in Soils . . . '77 



Surface Tension and Capillarity. 



58. Measurement of Capillarity . . . .78 



59. Capillary Attraction in Soils . . . .79 



Soil Thermometry. 



60. Absorption of Heat by Soil . . . .81 



Flocculation and Deflocculation of Soil. 



61. Effect of Acids, Alkalies, Salts, etc. . . .82 



62. Shrinkage of Clay on Drying . . . .83 



