CHAPTER XIV.

ABSORPTION BY SOILS OF SOLIDS FROM SOLUTIONS. ABSORPTION OF GASES, AIR OF SOILS, 267.—_Absorption of Solids_, 267.—Desalination, 267.—Decolorization, 267.—Complexity of Soil-Action, Physical and Chemical, 268.—“Purifying” Action of Soils on Gases and Liquids, 269.—Waste of Fertilizers, 269.—Variation of Absorptive Power, 270.—Generalities Regarding Chemical Action and Exchange, 270.—Drain Waters, 271.—Distinctions not Absolute, 272.—_Absorption or Condensation of Gases by the Soil_, 272.—Proof of Presence of Carbonic and Ammonia Gases in Soils, 273.—Absorption of Gases by Dry Soils. Figure, 274.—Composition of Gases Absorbed by Various Bodies from the Air. Table, 275.—Discussion of Table, 277.—_The Air of Soils_, 279.—Empty Space in Dry Soils, 279.—Functions of Air in Soils, 279.—Insufficient and Excessive Aeration, 280.—Composition of the Free Air of Soils, 280.—Carbonic Dioxid vs. Oxygen, 281.—Relation to Bacterial and Fungous Activity, 281.—Putrefactive Processes, 282.