Acids, action on litmus, 220.

    Adenoids, 51.

    Adulterants, detection of, 16.

    Air, characteristics of, 81-83, 86, 189.
      compressibility of, 91.
      expansion of, 10-11.
      humidity, 38, 39.
      pumps, 201-205.
      transmits sound, 269.
      weight of, 86.
     See Atmosphere.

    Alcohol, 234.
      in patent medicines, 260.

    Alizarin, 248.

    Alkali, 222.

    Alternating current, 351.

    Alum, 247.
      in baking powder, 230.

    Ammeter, 341, 343.

    Ammonia, 152.
      a base, 221-222.
      in bath, 226.
      in manufacture of ice, 98.
      neutralizing chlorine, 240.

    Ampere, 342.

    Anemia, 259.

    Angle, of incidence, 110.
      of reflection, 110.
      of refraction, 114.

    Aniline, 152, 245.

    Animal charcoal, 58.

    Animal transportation, 132.

    Antichlor, 240.

    Antipyrin, 259.

    Armature, 319, 320.
      dynamo, 350.
      motor, 335.

    Artificial lighting, 148-153.

    Atmosphere, 81.
      carbon dioxide in, 54-55.
      height of, 81.
      nitrogen and oxygen in, 262.
      pressure of, 82-86.
      water vapor in, 36-38.
      weight, 86.
      See Air.

    Atmospheric pressure, 82-86.

    Atomizer, 92.

    Atoms, 102.

    Automobiles, gas engines, 185.

    Axis of a lens, 119.

    Bacteria, 133.
      as nitrogen makers, 263.
      destroyed by sunlight, etc., 133, 250, 251.
      diseases caused by, 133.
      in butter and cheese, 133.

    Baking powder, 229-230.

    Baking soda, 227-229.

    Barograph, 87.

    Barometer, aneroid, 84-85.
      mercury, 84.
      use in weather predictions, 86-87.

    Bases, action on litmus, 221-222.
      properties, 220-222.

    Battery, electric, 311.

    Beans, as food, 66.
      roots take in nitrogen, 263.

    Bell, electric, 319-321.

    Benzine, 150.
      as a cleaning agent, 227.

    Benzoate of soda, 253.

    Bicarbonate of soda, in fire extinguisher, 55, 56.
      in Rochelle salt, 227.
      in soda mints, 231.
      in seidlitz powder, 231.

    Bicycle pumps, 202.

    Blasting, by electricity, 314.

    Bleaching, 237-243.
      by chlorine, 238-240.

    Bleaching powder, 239-240.

    Body, human, 63-64.
      a conductor of electricity, 292.

    Boiling, 31.
      amount of heat absorbed, 31-32.
      of milk, 32.
      of water, 77.
      point, 15.