Chapter VI. Physical Composition of Soils.

“ VII. Density, Pore Space, and Volume-Weight of Soils. “ VIII. Soil and Subsoil; Causes and Processes of Differentiation; Humus. “ IX. Soil and Subsoil; Organisms Influencing Soil-Conditions. Bacteria. “ X. Soil and Subsoil in their Relations to Vegetation. “ XI. Water of Soils; Hygroscopic and Capillary Moisture. “ XII. Water of Soils; Surface, Hydrostatic, and Ground water; Percolation. “ XIII. Water of Soils; Conservation and Regulation of Soil Moisture. Irrigation. “ XIV. Absorption by Soils of Solids from Solutions. Absorption of Gases. The Air of Soils. “ XV. Colors of Soils. “ XVI. Climate. “ XVII. Relations of Soils and Plant-Growth to Heat.

3. CHEMISTRY OF SOILS.