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 CHAPTER XIV. FORM IV: SPRING Method of Improving Home and School Grounds 263 Making and Care of a Lawn; References 264 Soil Studies 265 Weight 265 Subsoils 266 Fertilizers--experiments 268 Soil-forming Agents 268 Tilling the Soil 269 Garden Work--experiments in plots out-of-doors 270 Function of Parts of Plants 273 How the plant gets its food from the soil; germination of some of the common grains 274 Weeds 278 Vines 279 Wild Flowers 279 Planting of Trees, Shrubs, and Herbaceous Perennials in Home and School Grounds 280 Shade trees; transplanting 281 Animal Studies 283 Scale Insects 283 San Jose scale; oyster-shell bark-louse; cutworms; white grubs 283 Crayfish 285 Freshwater Mussel 286 Bird Study 287 Different Aspects of Nature Study 288 PREFATORY NOTE