96.

Compression pumps, 201, 205.

Concave lens, 118.

Condensation, 33.
heat set free, 40.

Conduction of heat, 25.

Conductivity metals, 321.

Conductors, electric, 321, 322.

Conservation, of energy, 58, 59.
of matter, 58, 59.

Convection, 24, 25.

Convex lens, 118.

Cooling, by evaporation, 35-36.
by expansion, 97.

Copper, in electric cell, 307.

Core, iron, 319.

Corn, bleached with sulphurous acid, 242.

Cotton, mercerized, 218.
bleaching, 241.
dyeing, 245-247.

Cough sirup, 258.

Crane, compound machine, 172.

Cream of tartar, 229.

Creosote oil, 254.

Crude petroleum, 149, 150.

Current, electric, 306, 312.
alternating, 349.
induced, 346-347.
measurement of, 340.
resistance, 312, 343, 345.
strength, 339, 340, 344.

Dams, 214-216.

Decay, 49.

Decomposition of soil by water, 70-74.

Degrees Fahrenheit and Centigrade, 15.

Density, 11.

Designs in cloth, printed, 248, 249.
woven, 249.

Developer in photography, 128.

Dew, 36, 37.

Dew point, 38.

Diarrhea, 251.

Diet, 62, 66.
economy on table, 66-69.

Discord, reason for, 271.

Disease, and surface water, 76.
relation of light to, 131-132.

Disease disinfectants, 250, 251, 252.

Distillation, 34-35.
in commerce, 35.
of petroleum, 149-150.
of soft coal, 150.
of water, 34, 35, 77.

Diving suits, 204.

Door bells, 319-321.

Drainage, of land, 194, 195.
sewage, 196, 198, 199, 201.

Drilled well, 199.

Drinking water, 75-77.
in camping, 195-196.
and rural supplies, 198, 201.

Driven well, 196-197.

Drought, 217.

Drugs, 255, 260.

Dry cell, 312.

Dyeing, 244-249.
color designs, 248.

Dyeing, direct, 245.
home, 247.
indirect, 247.
variety of color, 247.

Dyes, 218, 244, 245.

Dynamo, 346.
alternating current, 349.
source of energy, 346-347.

Ear, in man, 301-303.
care of, 303.

Earth, conductor of electricity, 326.

Echo, 277.

Economy in buying food, 66-69.

Effort, muscular, 155, 160.

Electric, battery, 311.
bell, 319-321.
bread toasters, 314.
conductors and non-conductors,