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.

CHAPTER XV.
COLORS OF SOILS, 283.—Black Soils, 283.—“Red” Soils,
284.—Origin of Red Tints, 285.—White Soils,
285.—Differences in Arid and Humid Regions, 286.—White
Alkali Spots, 286.

CHAPTER XVI.
CLIMATE, 287.—Heat and Moisture Control Climates, 287.—Climatic
Conditions, 287.—_Ascertainment and Presentation of
Temperature Conditions_, 288.—Annual Mean not a Good
Criterion, 289.—Extremes of Temperature are most
Important, 289.—Seasonal and Monthly Means, 289.—Daily
Variations, 290.—_The Rainfall_, 290.—Annual Rainfall
not a Good Criterion, 290.—Distribution most Important,
290.—_Winds_, 291.—Heat the Cause of Winds, 291.—Trade
Winds, 291.—Cyclones, 292.— Influence of the Topography
on Winds; Rains to Windward of Mountains, Arid Climates
to Leeward, 293.—General Distribution of Rainfall on the
Globe. Figure, 294.—Ocean Currents, 295.—The Gulf Stream,
295.—The Japan Stream, 296.—Contrast of Climates of N. W.
America, 297.—Continental, Coast and Insular Climates,
297.—Subtropic. Arid Belts, 298.—Utilization of the Arid
Belts, 299.

CHAPTER XVII.
RELATIONS OF SOILS AND PLANT GROWTH TO HEAT, 301.—Temperature
of Soils, 301.—Water Exerts Controlling Influence,
301.—Cold and Warm Rains, 302.—Solar Radiation,
302.—Penetration of the Sun’s Heat into the Soil,
302.—Change of Temperature with Depth, 303.—Surface
Conditions that Influence Soil Temperature, 303.—Heat of
High and Low Intensity, 304.—Reflection vs. Dispersion
of Heat, 304.—Influence of Vegetation, and of Mulches,
305.—Influence of the Nature of the Soil-Material,
306.—Influence of Evaporation, 307.—Formation of
Dew, 307.—Dew rarely adds Moisture, 308.—Dew within
the Soil, 308.—Plant Development under Different
Temperature-Conditions, 309.—Germination of Seeds; Optimum
Temperature for each Kind, 309.—Artificial Heating of
Soils; by Steam Pipes or Water, 310.