AIR, 240 always in motion, 293 bad conductor, 13, 177, 178 bad radiator, 219, 237 cold, 177 colder than blood, 181 composed of two gases, 27, 240 cooled by convection, 220 " by rain, 159 cools hot iron, 246 density diminished by rain, 337 descends when cold, 289 double current in a room, 290 dries linen, 160 elements of, 33 expanded by heat, 103 full of smells, 152 gets fire up, 50 healthful, 252 heated, 219, 245, 246, 289 " not by sun, 290 in a room, 252 inflammable, _see hydrogen_ in summer, 313 of cities unhealthy, 243, 253 of the country healthy, 243, 252 on land colder than on water, 224 on land cold at night, 230 preserved normal, 244 purified by lightning, 27 rusts iron, 257 still before a tempest, 146 strong, 108 varies in temperature, 335 Aisles famous for echoes, 417 Alcohol, 109, 270, 271 ALE, 109 bottled, 268 froth of, 109 froth increased by heat, 268 Alkali, 45 Anenometer, 314 Anglers hate a magpie, 153 Angle of incidence, 370 of reflection, 370 Animal heat, 83, 85, 243, 277 Animals and vegetables co-dependent, 244 Ants love honey-dew, 221 Appetite, 89, 90, 91 (_See hunger._) Apples full of air, 105 roasted, 105 soft, 106 April showers, 307 Aqua fortis, 426 Argand lamps, 83 Arnott's stoves smell of sulphur, 56 smoke, 69 Ascent in balloons painful, 145 Ashes soften water, 345 Asses bray in wet weather, 148 Aurora borealis, 142, 285 coloured, 143 white, 142 a prognostic, 143 Avenues, 380 Azote, _see nitrogen_ Bales catch fire spontaneously, 57 Balloons, 146 inflated, 109 rise, 110 Balls of fire, 6 Banisters wet, 216 Barley malted, 270 BAROMETER, 317 affected by cold, 328 " frost, 329 " heat, 328 " thaw, 329 " wind, 327 rules for its rise and fall, 330 sudden change in, 330 use of, 319 varies most in winter, 327 " least in summer, 327 when highest, 328 " lowest, 328 Barren land collects no dew, 209 Bass notes in music, 412 Bass preserves flowers from frost, 206 Bathing, danger of, 387 with ether for inflammation, 157 Beakers broken by hot water, 126 Beasts covered with hair, 176 Beds damp, 157 BEER, fermentation of, 269 flat, 273 froth increased by bottling, 268 froth increased by heat, 268 raisins and raw meat improve it, 273 stale, 275 soured by lightning, 27 not _old_ beer, 27 spoiled, if the vent-peg be left out, 273 yeast added to make it work, 271 Beer-vats dangerous, 265