INDEX 



(References to illustrations are indicated by asterisks accompanying page num- 

 bers. When an asterisk precedes the citation of a group of pages it means that 

 several illustrations are included) 



Absorption by plants, *234-240 



Agar, 81, 82 



Air, 1*, 102 



Air, composition of, 65, 66 



Air, compressibility of, 49, 50, 52 



Air, expansion of, 50-52 



Air, expansion when heated, 10, 11*, 



12, 13 



Air, how warmed, 10, 19, 20 

 Air, movements of, 140* 

 Air, properties of, *1~15 

 Air, structure of, 49-54 

 Air, water of, *21-27 

 Air, weight of, *3-10 

 Air a mixture, 55, 65 

 Air and combustion, *55~64 

 Air pressure, *4-10, 119, 121, 122, 



129, 130 



Air pressure and altitude, 8*, 9*, 10 

 Air pressure and winds, *28~45 

 Air pressure shown on weather maps, 



*29-45 



Alcohol, 111, 135 

 Alcohol and evaporation, 111 

 Altitude and air pressure, *8-10 

 Altitude of sun, *16-18 

 Aluminum, 61, 135 

 Ammonia and cold storage, 111 

 Aneroid, 5*, 6, 8* 

 Animals as soil formers, 197, 200, 



202, 203 



Anopheles, 98, 99* 

 Anti-cyclone, 35, 37, 38* 

 Antimony, 61 

 Argon, 65, 66 

 Arsenic, 61 

 Artificial selection, 294-297*, 298, 



299 



Ascent of water, 238, 239* 

 Assimilation, 251, 252, 259 

 Atmospheric pressure, *5-10, *28- 



45, 119, 121, 122, 129, 130 



Atomic theory, 59, 60 

 Atoms, 59, 60, 62-64, 66 

 Automobile, 10 



Bacteria, *85-97, 156, 157, 225, 226 

 Bacteria, colonies of, 82*, 91* 

 Bacteria, distribution of, *88-97 

 Bacteria, photomicrographs of, 86* 

 Bacteria, useful, 87 

 Bacteria and decay, 86 

 Bacteria and disease, 87 

 Bacteria in cultivation, 87 

 Bacteria in water, 156, 157 

 Bacteria of the air, 79-82* 

 Bacteria of the soil, 225, 226 

 Bacteria upon bread, 88, 89 

 Bacteriology, 85, 86 

 Balance of life, 285-289 

 Balloons, 133, 134 

 Barium, 61 

 Barograph, 5*, 8 

 Barometer, *5-8, 29-48, 129, 130 

 Barometer, aneroid, 5*, 6, 8* 

 Barometer, graduation of, 7*, 8* 

 Barometer, mercurial, 6*, 7*, 129, 



130 



Barometric readings, *29-48 

 Bees, overproduction of, 283 

 Bicycle, 1, 10 



Birds, reproduction of, 275, 276 

 Bismuth, 61 

 Bladder glass, 4*, 6 

 Blade of leaf, 69, 70* 

 Blizzard, 40 

 Blood poisoning, 87 

 Boiling, *104-108 

 Boiling and elevation, 106* 

 Boiling and melting, 108 

 Boron, 61 

 Brass, 135 



Bread, in relation to bacteria, 88, 89 

 Breathing, 268 



303 



