water in, 75.

Foot pound, 172.

Force and motion, 156, 157.
and work, 156, 157.
magnetic lines of, 329-331, 334.
muscular, 155, 160.

Force pumps, 192, 193.

Forests and water supply, 216-217.

Forging of iron, 40, 41.

Formaldehyde, 253.

Freezing, effect of salt, 44.
effect on ground and rocks, 42.
expansion of water on, 41.
ice cream freezer, 44.

Frequency in music, 273, 275.

Fresh air, 22-24, 49.
amount consumed by gas burner, 22.
and health, 49, 50.
in underground work, 202.
in work under water, 203-205.

Friction, 173, 174.
losses by, 174, 210.
source of heat and fire, 47.

Frost, 36, 37.

Fruit, canned, bleached with sulphurous acid, 242.
colored with coal tar dyes, 253.

Fuel value of foods, 60-62.
table of fuel values, 67.

Fulcrum, 159, 160.

Fumigation, 251.

Fundamental tone, 290, 291, 292.

Furnace, hot air, 19.

Fuse, 340.

Fusion, heat of, 40.

Galvanometer, 341.

Gas, acetylene, 152, 153.
and unburned carbon, 151.
coal, 151, 152.
effect of heat on volume, 96, 97.
effect of pressure on volume, 95-96.
engine, 185-186.
for cooking, 151, 152.
illuminating, 92, 93, 150, 151.
liquefaction, 97, 98.
meter, 93, 94.
natural, 152.

Gasolene, 149, 150.
as cleaning agent, 227, 243.
in gas engine, 185, 186.

Gauge, pressure, 92-94.

Gelatin, plate and film, 129.

Glass, kinds of, 119.
molding of, 40.
non-conductor, 321.

Grape juice, fermented with millet, 233.

Gravity cell, 309, 310.

Grease, and lye, 221.
and soap making, 223.

Gulf Stream, 24.

Hard water, and soap, 225.

Harp, 295.

Headache, 124, 125.
powders, 259.

Health, effect of diet, 62, 64.

Heat, 9.
absorbed in boiling, 31-32.
and disease germs, 250.
and food, 252.
and friction, 47.
and light, 142, 147.
and oxidation, 45, 48, 49.
and wave motion, 145-147.
conduction, 25.
convection, 24, 25.
from burning hydrogen, 80.
from electricity, 312-315, 339.
needed to melt substances, 39.
of fusion, 40.
of vaporization, 32.
produced by compression, 96.
relation of water to