Experiments and Exercises 



Sound Transmitted Through Air 170 



Sound Transmitted Through Substances Other Than Air ... 171 



Speed of Sound 171 



Variation in Speed of Sound 172 



Production of Sound by Vibrations 172 



Testing the Hearing 177 



Light Rays Travel in Straight Lines 182 



Nature and Cause of Shadows 182 



Mirror Images 184 



Effects of Lenses 187 



Inverted Images in a Camera 188 



Formation of Carbon Dioxide by a Candle Flame 191 



Carbon in a Bunsen Burner 192 



Attraction of Iron Filings by Magnets 196 



Polarity 196 



Attraction and Repulsion of Magnetic Poles 196 



Attraction of Different Substances by Magnets 197 



Magnetizing Iron and Steel 197 



Principle of the Compass 198 



Induced Magnetism 198 



Magnetic Field 199 



Magnetic Fields of Two Magnets 199 



The Dipping Needle 201 



Static Electricity 204 



A Simple Cell 209 



Effect of an Electric Current on a Magnetic Needle .... 215 



Induced Currents 223 



The Lever 244 



Why a Metal Ship Floats 275 



Layers in Sedimentary Rock 291 



The Paramecium 319 



The Amoeba 321 



Effect of Tobacco on Cell Life 345 



Generation of Heat in the Body 349 



Production of Carbon Dioxide in the Body 349 



Action of Lungs and Diaphragm in Breathing 350 



Characteristics of Some Nutrients and Their Presence 



in Common Foods 356-357 



Test for Starch 357 



Test for Grape Sugar 357 



