al, 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.

Bomb calorimeter, 61.

Borax, as meat preservative, 253.
as washing powder, 226.

Boric acid, as meat preservative, 253.

Boyle's law, 95-96.

Bread, 232-233.
unleavened, 233.

Bread making, 232-235.

Breathing, hygienic habits of, 50.
by mouth, 50-51.

Burns, treatment of, 52-53.

Butter, adulteration test, 16.
bacteria in, 133.

Buttermilk, 230.

Caisson, 203-204.

Calcium carbide, 152-153.
in making nitrogenous fertilizer, 264.

Calico printing, 249.

Calorie, 27-28, 61-62.

Calorimeter, 61.

Camera, 128-129.
films, 129.
lens, 129.
plates, 129.

Camping, water supply, 195-197.

Candle, 148-149.
as standard for light-measure, 104-105.

Candle-power, 1