CONTENTS XXI 



teurization. Number of Bacteria Allowed in Milk. Uses of Carbon 

 Dioxide in Cooking. Use of Ammonium Carbonate. Use of Baking 

 Soda. Use of Hydrochloric Acid in Baking Soda. Baking Soda and 

 Molasses. Sour Milk Bread. Baking Soda and Cream of Tartar. 

 Phosphate Baking Powder. Burnt Alum Baking Powder. Yeast in 

 Bread Making. Food Preservation and Adulteration. Nostrums. 



CHAPTER VIII 

 WATER 257 



Facts about Water. Composition of Water. Electrolysis. Spe- 

 cific Gravity. Submarines as Sinking and Floating Bodies. Hydrom- 

 eter. Water Pressure. Deep Sea Fish. Water Systems. Water 

 as a Solvent. Cleaning of Fabrics. Water Meters. Leaks in Faucets. 

 Source of Fresh Water. Test for Impurities in Water. Hard and 

 Soft Water. Drinking Fountains. Cisterns. Wells. Rivers and 

 Streams. Sewer Gas. Traps. Peppermint Test. 



CHAPTER IX 



GERMS AND DISEASE 289 



Protozoa. Bacteria. Cause of Disease. Diseases Caused by 

 Protozoa. Diseases Caused by Bacteria. Prevention of Diseases. 

 Disease of Fruits and Vegetables. Bacteria Useful to Man. Methods 

 of Preventing and Spreading Disease. 



CHAPTER X 

 LIGHT AND ITS RELATION TO THE WORLD , 324 



Light Waves. Sources of Light. How Light Travels. Trans- 

 parent, Translucent and Opaque Objects. Shadows. Reflection. 

 Why Images are Seen in Plain Mirrors. Kinds of Mirrors. Para- 

 bolic Mirrors. Refraction in a Prism. Why a Prism Breaks up Sun- 

 light into Colors. The Rainbow. Color of the Sky. Sunset Colors. 

 A Mirage. Use of Lenses. Motion Picture Machines. The Eye. 

 Lens of the Eye. Near and Far Sightedness. Evidence of Eye Strain. 

 Abusing the Eye. Objections to Wearing Glasses. Varieties of 

 Lenses. The Iris. The Orbits. The Eyeball. The Sclerotic Coat. 

 The Choroid Membrane. The Aqueous Humor. The Vitreous 

 Humor. The Protectors of the Eye. Optical Illusions. Blind Spot. 

 Illumination. Methods of Lighting. Computing the Cost of Light- 

 ing. Color and Chemical Action of Lighting. Color Blindness. 



