ELEMENTS OF GENERAL SCIENCE 



viii 



PAGB 



CHAPTER VI. COMPOSITION OF THE AIR-ATOMIC THEORY 63 



Questions for Discussion. The air not a simple substance. A 

 burning candle. Products of the flame. Water produced by a 

 flame. Composition of water. The molecule of water. Explana- 

 tion of some chemical terms. Formation of water in the flame. 

 Other products from the flame. Carbon dioxide formed by the 

 flame. Some further facts about carbon dioxide. Gases of the 

 air. Abundance of oxygen. Nitrogen and argon. 



CHAPTER VII. RELATION OF AIR TO FOOD MANUFACTURE 75 



Questions for Discussion. Sources of our food. Source of plant 

 food. Food of plants. The place where food is made. Some 

 problems. Structure of leaves. Structure of the epidermis. Struc- 

 ture of the leaf interior. Entrance of materials into the leaf. 

 Manufacture of carbohydrates. The waste material. The source 

 of energy. Importance' of chlorophyll. Sugar and starch in the 

 leaf. Comparison with a factory. Importance of plant synthesis. 

 Manufacture of fat. Manufacture of protein. 



CHAPTER VIII. DUSTS, MOLDS, AND BACTERIA OF THE AIR 87 



Questions for Discussion. Abundance of dust. The sources of 

 dust. Living dust. Tests for living materials. The dependent 

 plants. Size and growth of bacteria. Study of yeast, molds, and 

 bacteria. Relation of bacteria to decay. Bacteria and disease. 

 Useful bacteria. Useful yeast. Bacteria in cultivation. 



CHAPTER IX. DISTRIBUTION OF BACTERIA AND OTHER 

 DISEASE GERMS 97 



Questions for Discussion. Means of distribution. Bacteria upon 

 carelessly handled bread. Protecting ourselves and others. Trans- 

 mission of typhoid bacteria. Importance of pure milk and water. 

 Results of improved hygienic conditions. Results of anti-typhoid 

 vaccination. Typhoid bacteria carried by flies. The life history 

 of the house fly. How house flies carry bacteria. Disposal of 

 house flies. Cleanliness and disease. Malaria caused by an animal 

 organism. The life history of the mosquito. How the mosquito 

 carries malaria. How to destroy mosquitoes. Different kinds of 

 mosquitoes. Disease germs distributed by other insects. 



PART II. WATER AND ITS USES 



CHAPTER X. ICE, WATER, AND STEAM 113 



Questions for Discussion. When water freezes. Changing water 

 to steam. Other facts about steam. The usual states of matter. 

 Distillation. Use of thermometers in candy-making. Boiling and 

 melting points. Evaporation. Cooling effects. Ice machines and 

 cold storage. Perspiration. Amount of water evaporated by the 

 air. Evaporation from plants transpiration. The principle of 

 the refrigerator. Freezing mixtures. 



