Vlit HOW CHOPS FKED. 



CHAPTEli II. 



Origin and Formation op Soils 10(j 



§ 1. Chemical Elements of Rocks 107 



§ 2. Mineralogical Elements of Rocks 108 



§ .3. Rocks, their Kinds and Characters 117 



§ 4. Conversion of Rocks into Soil 12* 



§ 5. Incorporation of Organic Matter with the Soil, and its Effects 135 



CHAPTER III, 

 Kinds op Soils, their Definition and Classipication. 



§ 1. Distinctions of Soils based upon the Mode of their Formation or Deposi- 

 tion 142 



S 2. Distinctions of Soils based upon Obvious or External Characters 146 



CHAPTER IV. 

 Phtsioal Characters of the Soil 167 



S 1. Weight of Soils 158 



y S. State of Division 159 



§ 3. Absorption of Vapor of Water 161 



§ 4. Condensation of Gases 165 



§ 5. Power of Removing Solid Matters from Solution 171 



I 6. Permeability to Liquid Water. Imbibition. Capillary Power 176 



§ 7. Changes of Bulk by Drying and Frost 183 



§ 8. Adhesiveness 184 



§ 9. Relations to Heat 186 



CHAPTER V. 



The Soil as a Source op Food to Crops : Ingredients whose Elements 

 ARE OP Atmospheric Origin. 



S 1. The Free Water of the Soil in its Relations to Vegetable Nutrition 199 



§ 2. The Air of the Soil 217 



S 3. Non-nitrogenous Organic Matters. Humus 222 



§ 4. The Ammonia of the Soil 238 



§ 5. Nitric Acid (Nitrates) of the Soil 251 



§ 6. Nitrogenous Organic Matters of the Soil. Available Nitrogen 274 



§ 7. Decay of Organic Matters 289 



§ 8. Nitrogenous Principles of Urine 293 



I 9. Comparative Nutritive Value of Ammonia-Salts and Nitrates 300 



