Index 



615 



Gases, expansion of, 64, 85, 153 

 Gasoline, 129, 139, 143 ff., 314 



motor, 330 ff., 400 

 Generator, electric, 325, 327 

 Germicide, 582 ff., 597 

 Gilbert's theory of magnetism, 373 ff. 

 Girder, principle of, 280 ff. 

 Glacial moraine, 457, 474 

 Glass, 168, 421 ff. 

 Glucose, 519 

 Gluten, 567 

 Gneiss, 414 

 Grades, 268 ff., 318 

 Gradient, of roads, 272 ff., 318 



of winds, 25 

 Grafting, 502, 503 

 Granite, 408 ff., 415 

 Graphite, 128, 414, 415 

 Gyro-compass, 375 ff. 

 Gyroscope, 375 ff., 399 



Hail, 36, 52, 55 



Harbors, 379 ff., 387 



Heat, absorption of, 109, 152 ff. 



capacity of substances, 100 ff., Ill, 



142, 307 

 of water, 101, 142, 304 



-energy, 107 ff., 295 ff., 306 ff., 31-1 



measuring, 141 ff. 



of the liquid, 304 



of melting, or fusion, 149, 156 



of steam, 303 ff., 305, 309, 312, 315 

 measuring, 306 



sources of, 59 ff., 93, 108 



transfer of, 93 ff. 



units of measure of, 141 ff., 306 



values of fuels, 142 ff., 144 

 Helium, 90, 546 

 Hematite, 434, 540 

 Heredity, in plants, 480, 493, 503, 514 



Mendel's law of, 505 ff., 508, 511 ff. 

 Hero's steam engine, 364 ff. 

 Hookworm, 217 

 Horsepower, 243 ff., 249 



and efficiency of machines, 243 ff. 



248 



Humid soil, 457 

 Humidity of atmosphere, 43 ff., 103, 



305 ff. 



Humus, 455 ff., 471, 474 

 Hurricanes, 22 ff., 30 ff., 51 

 Hybridization, 497 ff., 503 



Hybrids, 497 ff., 503, 506 ff., 514 



Hydraulic press, 230 



Hydrocarbons, 129, 139, 144, 162 ff., 



413 



Hydrochloric acid, 120, 519 

 Hydrogen, 117 ff., 120 ff., 138, 144, 



391 ff., 515 

 peroxid, 122, 546, 584 

 Hygienic lighting, 182 

 Hygrometer, 46 ff., 54 



Ice, manufacture of, 151 ff. 

 Ice cream freezer, 150 

 Igneous rock, 410, 413 ff. 

 Illuminants, 159 ff. 

 Illumination, standards of, 176 ff. 

 Immunity, artificial, 591, 593, 603, 

 605 



biological or phagocytic theory of, 

 601 ff. 



chemical theory of, 599 ff., 601 ff. 



how acquired, 532, 591, 602 ff. 



natural, 591, 602 

 Improvement of plants, 481, 496 ff., 



503, 511 ff. 

 Incandescent lamp, electric, 160, 165 



ff., 183 



Inclined plane, 268 ff. 

 Inertia, 275 ff. 



law of, 276 

 Infantile paralysis, 533 

 Infectious diseases, 217, 588, 589, 603 

 Inflammable air, 117 

 Inland waterways, 380 ff. 

 Inoculation, 532, 591 ff., 603 ff. 

 Insects and cross-pollination, 490 ff., 

 494 



and human health, 523, 532, 534, 



590 



Insulators, 96, 167 ff. 

 Iron, production of, 430, 431, 434 ff., 

 540 



properties of, 168, 431 ff., 491 ff. 



uses of, 429 ff. 



Iron ore, distribution of, 386, 432, 433, 

 450 ff. 



kinds of, 433, 450 



mining, 435, 436, 451 



reduction of, 438 ff., 451 

 Irrigation, 201, 203 ff., 465 

 Isobars, 9 ff. 



and altitude, 10 



