vi ELEMENTS OF GENERAL SCIENCE 



PAGE 



composition of water. The molecule of water. Explanation 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. The gases of the air. 

 More about oxygen. Nitrogen and argon. Summary. 



CHAPTER VII. RELATION OF AIR TO FOOD MANUFACTURE 07 



Sources of our food. Source of plant food. Food of plants. The 

 place where food is made. Some problems. Structure of the leaves. 

 Structure of the epidermis. Structure of the leaf interior. En- 

 trance of materials into the leaf. Manufacture of carbohydrates. 

 The waste material. The source of energy. Importance of chloro- 

 phyll. Photosynthesis. Sugar and starch in the leaf. Comparison 

 with a factory. Importance of photosynthesis. 



CHAPTER VIII. DUSTS, MOLDS, AND BACTERIA OF THE AIR 70 

 Dust in the air. Dust is everywhere. The nature 8f dust. Living 

 dust. Dependent plants. Bacteria. Bacteriology. Relation of 

 bacteria to decay. Bacteria and disease. Useful bacteria. Bac- 

 teria in cultivation. 



CHAPTER IX. DISTRIBUTION OF BACTERIA AND OTHER 



DISEASE GERMS 88 



Distribution of bacteria. Bacteria upon carelessly handled bread. 

 Transmission of typhoid bacteria. Importance of pure milk and 

 water. Results of improved hygienic conditions. Typhoid carried 

 by flies. The life history of house flies. How flies carry bacteria. 

 Disposal of house flies. Cleanliness and disease. Practical ques- 

 tions. Mosquitoes and malaria. Malaria caused by an animal 

 organism. The life history of the mosquito. How mosquitoes 

 carry 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 103 



The three states of matter. When water freezes. Changing water 

 to steam. Other facts about steam. Distillation. Boiling and 

 melting points. Evaporation. Laws of evaporation. Cooling 

 effects. Ice machines and cold storage. Perspiration. Amount of 

 water evaporated by the air. Evaporation from plants : transpira- 

 tion. Refrigerators. Freezing mixtures. 



