CONTENTS Xlll 



Diffusion Other forms of solutions Alloys Solution and 

 change of state Emulsions Practical exercises. 



CHAPTER XX. PRECIPITATION, FILTRATION AND DISTILLATION. 139 

 Precipitates Filters and filtering Distillation Practical 

 exercises. 



CHAPTER XXI. ACIDS, BASES AND SALTS 145 



Nature of Acids Bases Formation of salts -Practical exer- 

 cises. 



CHAPTER XXII. LIGHT AND VISION 149 



Radiation from luminous bodies Reflection of light Refrac- 

 tion -Lenses The camera Persistence of images -Various 

 effects of light Phosphorescence 'Artificial lighting Prac- 

 tical exercises. 



CHAPTER XXIII. COLOR 160 



Composition of light Absorption and reflection Fluorescence 

 Complimentary colors The eye and color Practical exer- 

 cises. 



CHAPTER XXIV. SOUND 167 



Vibrations in air Echoes Sympathetic vibrations Distin- 

 guishing sounds Practical exercises. 



CHAPTER XXV. FORCE AND MOVING BODIES '. . 173 



Momentum and inertia Friction Advantages of friction 

 Gravity Equilibrium Practical exercises . 



CHAPTER XXVI. LONGITUDE AND TIME 181 



Locating points on a globe Distances on the earth Time on 

 the earth Time belts The earth's axis and the zones Prac- 

 tical exercises. 



CHAPTER XXVII. MACHINES 188 



Mechanical advantage Simple machines The lever and its 

 adaptations The inclined plane and its adaptations The hy- 

 draulic press Practical exercises. 



CHAPTER XXVIII. MAGNETISM 194 



The lodestone Poles of the magnet The earth a magnet 

 The compass Lines of force Practical exercises. 



CHAPTER XXIX. STATIC ELECTRICITY 199 



Electricity by friction Two kinds of electricity The electro- 

 scope Insulators -The Ley den jar Lightning Practical exer- 

 cises. 



CHAPTER XXX. CURRENT ELECTRICITY 205 



Useful electricity The voltaic cell Direction of the current 



