INDEX 



11 



References are to pages 



Household Continued 



building-material and cloth- 

 ing 307 



homes dependent upon soil . 307 

 minerals and mineral oils 254-255, 

 516-519 

 see also Sanitation 



Humidifiers 107-108 



Humidity 102-107, 133 



absolute humidity . . . . 102 



causes of 104 



comfort vs 106-107 



dew-point 102-104 



hygrometer 103 



relative humidity . . . . 102 

 saturation 102 



Humors (of eye) 414 



aqueous 414 



vitreous 414 



ttamus (constituent of soil) . 311, 

 314-320, 327, 345 



bacteria in 314-315 



qualities of . . . . .319-320 



Hydrogen (a gas) . . . 136, 167, 

 425, 484-485 



constituent of food .... 456 

 constituent of water . . 136, 167 

 formed in voltaic cell by elec- 

 tricity 484-485 



Hydrogen peroxide (disin- 

 fectant) . . 444 



Hydrometer 153 



Hygrometer 103-104 



Ice 127,137-138,279, 



285-287, 293-295, 303 

 a factor in earth's surface 



changes 303 



contraction of, after forma- 

 tion . . ... . . . 138 



erosion by 285 



expansion of, while forming . 138 



formation of 137-138 



glaciers, icebergs and ice 

 fields 285-301,304-305,525-528 



manufacture of 127 



power of 279 



pressure of . . . . = . . 138 

 weight of 138 



[Humiliation ; see Light 

 Imperial Valley (fertility of) . 173 

 Incandescent lamps .... 488 

 Incidence (angle of) .... 352 



law of 352 



Inclination (of axis) .... 26 



Industries 546-547 



Inertia 42-49, 58 



laws of . . . . . 43, 44, 48, 49 

 [nfluenza (bacterial disease) . 442 

 Inorganic matter (or substance) 426 

 Insects (invertebrates) 400-405, 533 



beneficent 403-405 



productive 403-405 



bee 403-405 



silkworm 403 



harmful ..403 



of the sea . 533 



of the soil 403 



Insolation 209-210 



Intakes (cribs) 204 



Intensity 349-350,477 



of heat 350 



law of 350 



of light . . , i . 349-350, 477 



law of 477 



of magnetism 477 



of sound 477 



International Date Line . . 35, 40 



Intestines 420-421 



large 421 



small 420-421 



function of . . . . . . 421 



liver 421 



pancreas 421 



Inventions . 39, 91-92, 103-107, 



111, 117-131, 137, 143, 147-150, 



202-206, 416, 459-474, 467-478, 



483, 486-501 



Invertebrates . . . 317-319,345, 



400-405, 423, 533-534 



insects . . . 400-405,533-534 



protozoa . . 400-401,423,452 



shellfish 400 



worms . . 317-319,345,401-402 



Iris (of eye) 414 



Iron and steel (magnet-making 



minerals) 476 



Irrigation 330-331, 346 



