Chapter 13

Forest Trees 246 Evergreens; Wood Specimens 246

Fruits 247

Weeds and Weed Seeds 248

Physical Science Phase of Nature Study 248 Water Pressure--exercises 248 Study of Air 249 The barometer; the common pump; expansive force of air; composition of air; oxygen; carbon dioxide; impurities of air 250 Solutions of Solids 255 Solutions of Liquids 256 Solutions of Gases 256 Limestone 256 Carbon 257 Hydrogen 258 Magnets 258 Electricity 259 Steam 260 Farm tools--machines; problems 260