INDEX

Absorption, of heat by lampblack, 143-144. of gases by charcoal, 57. of light waves, 135-138.

Accommodation of the eye, 123.

Acetanilid, 259.

Acetylene, as illuminant, 152-153. manufacture of, 152-153. properties of, 220.

Acid, boric, 253. carbolic, 152, 251, 252. hydrochloric, 55, 80, 227, 238, 241. lactic, 230. oxalic, 247, 248. salicylic, 253. sulphuric, 55, 80, 240, 241, 307. sulphurous, 242.

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.

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, 105-107.

Carbide, calcium, 152-153, 264.

Carbohydrates, 64-65, 149.

Carbolic acid, 152. as disinfectant, 251.

Carbon, 56, 66.

in voltaic cells, 308.

Carbon dioxide, 53. as fire extinguisher, 55-56. commercial use, 55-56. in baking soda, 228. in fermentation, 234. in health, 54. in plants, 55. preparation of, 55. source of, 53. test for, 228.

Catarrh, 259.

Caustic lime, 222..

Caustic potash, 222.

Caustic soda, 218, 222. to make a salt, 227.

Caves and caverns, 71.

Cell, dry, 310. gravity, 309-310. voltaic, 306-308, 310.

Cells of human body, 63, 64, 66.

Centigrade thermometer, 15.

Central heating plant, 19.

Chalk, in making carbon dioxide, 55.

Charcoal as a filter, 57. commercially, 57. preparation, 57-58.

Chemical action, and electricity, 307, 315-317. and light, 126, 127.

Chemistry, in daily life, 218, 219.

Chills, 38.

Chloride of lime, in bleaching, 240. disinfectant, 251.

Chlorine, and hydrogen, 239. effect upon human body, 239. in bleaching, 238-240. influence of light upon, 126. presence in salt, 227.

Circuit, electric, 321. local, in telegraph, 325-326.

City water supply, 206-212.

Clarinet, 297.

Cleaning of material, 226, 243.

Climate, influenced by presence of water, 29, 40.

Clover, nitrogen producers, 263.

Coal, 30.

Coal gas, 150, 151. by-products, 152.

Coal oil, 149, 150.

Coal tar dyes, 152, 218, 245.

Cogwheels, 170.

Coil, current-bearing, 320. magnetic field about, 331-333.

Coke, 152.

Cold storage, 97.

Color, 134-141. and heat, 142, 143. influenced by light, 137. of opaque bodies, 136, 137. of transparent bodies, 135, 136.

Color blindness, 140, 141. designs in cloth, 248, 249.

Colors, compound, 138, 139. essential, 139-140. primary, 135. simple, 138. spectrum, 134-135. variety in dyeing, 247, 248.

Combustion, heat of, 45. spontaneous, 52.

Commutator, 335.

Compass, 328.

Compound colors, 138, 139.

Compound machine, 171.

Compound substances, 103.

Compression of air, 91, 92. cause of heat, 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, 321-322. cost of, energy, 352. current, 306, 312. flatiron, 313. heating pad, 314. lights, 314. street cars, 337.

Electricity, heat, 312-315, 339. as a magnet, 319, 331-333. practical uses of, 312-317.

Electrodes, of cell, 308.

Electrolytic metals, 317.

Electromagnets, 319.

Electromotive force, 308. unit of, 344.

Electroplating, 315.

Electrotyping, 317.

Elements, 102-103.

Emulsion, 224.

Energy, conservation of, 58, 59. transformations of, 58, 59.

Engine, steam, 183-185. gas, 185-186. horse power, 173.

Erosion, 73-74.

Essential colors, 139-140.

Evaporation, 35-39. cooling effect, 35-36. effect of temperature on, 35, 36. effect of air on, 38. freezing by, 98. heat absorbed, 36. of perspiration, 38.

Expansion, of air, 10, 11. cooling effect of, 97. disadvantage and advantage of, 11-13. of liquids, 9-11. of solids, 10, 11. of water, 9, 10, 11, 12. Eye, 122-125. headache, 124, 125. how focused, 122, 123. nearsighted and farsighted, 123. strain, 125.

Fahrenheit thermometer, 15.

Fats, 65. in soap making, 223.

Fermentation, 232-236. by yeast, 234-236.

Ferric compounds, 248.

Fertilizers, 262-265. nitrogen, 262. phosphorus, 263, 264. potash, 263-265.

Field magnet, 336.

Filings, iron, 329.

Film, photographic, 129.

Filter, charcoal, 57.

Filtering water, 77.

Fire, 9. and oxygen, 45, 47. and tinder box, 47. making of, 51. primitive production of, 47. produced by friction, 47. spontaneous combustion, 52. sores and burns, 52-53. extinguisher, 55, 56.

Fireless cooker, 25, 26.

Fireplaces, 17, 18.

Fixing, in photography, 128.

Flame, hydrogen, 80.

Flood, Johnstown, 214, 215. relation to forests, 217.

Flour, self-raising, 231.

Flume, 177.

Flute, 297.

Focal length, 118.

Focus, of lens, 118.

Fog, 37.

Food, 60-69. carbohydrates, 64, 65. economy in buying, 66-69. fats, 65. fuel value of, 60-62. need of, 63, 64. preservatives, 252. proteids, 66. value, 67. waste, 60. 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 weather, 29, 40. set free by freezing water, 40. sources of, 29-30. specific, 28-29. temperature, 27. unit of, 27, 28.

Heating effect of electric current, 312-315.

Heating of buildings: central heating plant, 19. fireplaces, 17-18.

Heating, furnaces, 19. hot water, 19-22.

Helix, 318.

Horse power, 173, 351.

Hot water heating, 19-22.

Hues, primary, 135.

Humidity, 38. proper percentage for health and comfort, 38, 39.

Humus, 216, 217.

Hydrocarbons, 149.

Hydrochloric acid, composition, 227. in bleaching, 241. to make a salt, 227. to make carbon dioxide, 55. to make chlorine, 238. to make hydrogen, 80.

Hydrogen, 65, 66. and chlorine, 239. and water, 79. chemical conduct, 126-127. flame, 80. in voltaic cell, 307. peroxide, 53, 252. preparation, 80. to liquefy, 97.

Ice, lighter than water, 42. manufacture of, 98, 99.

Ice cream freezers, 44.

Illuminating gas, manufacture of, 150, 151. measurement of quantity consumed, 93, 94. test of pressure, 92, 93.

Illumination, intensity of, 105, 106.

Image, in mirror, 108, 111.

Incandescent lighting, 107, 314.

Incidence, angle of, 110.

Inclined plane, 162-166. screw, 166. wedge, 166.

Indigo, 218.

Induced current, 346-347.

Ink spots, removal of, 243.

Insoluble substances, 71.

Insulators, electric, 324.

Intensity, of light, 105-107. of sound, 270-271.

Interval, in musical scale, 283.

Iron, forging, 41. filings, 329. galvanizing, 49. oxidation of, 48.

Irrigation, 193-194.

Isobaric lines, 88, 91.

Isothermal lines, 89, 91.

Johnstown flood, 214, 215.

Kerosene, 149, 150.

Kilowatt, 351.

Lactic acid, 230.

Leaves, 132, 262.

Lens, 117-121. concave, 118. converging, 118. crystalline, of eye, 122. focal length, 118. material, 119. refractive power, 119.

Lever, 158-162. examples, 160-162. fulcrum, 159, 160.

Life, and carbon dioxide, 54. and nitrogen, 261. and oxygen, 49, 54.

Lifting pumps, 189-192.

Light, absorption, 135-138. and heat, 142-147. a wave motion, 145-147. bent rays, 113, 114. chemical action, 126-127. disease, 131-132. essential to life, 131, 132. fading illumination, 105, 106. influence on color, 134. reflection of, 109-112. refraction of, 113-125. travels in a straight line, 108. white, composed of colors, 134.

Lighting, artificial, 148-153.

Lime, chloride of, 240, 251.

Limewater, 220. and carbon dioxide, 228.

Linen, bleaching, 241. dyeing, 245-247.

Lines, of force, 329-331, 334. isobaric, 88, 91. isothermal, 89, 91.

Liquefaction of gases, 97, 98.

Liquid air, 98.

Liquid soap, 223, 224.

Litmus, action of acids, 220. action of bases, 221, 222. action of neutral substance, 222.

Logwood dyes, 245, 247, 248.

Los Angeles aqueduct, 211.

Lye, 221, 222.

Machines, compound, 171. inclined plane, 162-166. lever, 158-162. pulley, 166-169. wheel and axle, 169-171.

Madder, for dyes, 245.

Magnet, 328. electro-, 319. field of, 329-331. lines of force about, 329-331. poles of, 330-332. properties of electricity, 318.

Magnetic, needle, 328. poles, 329-331.

Magnifying power, of a lens, 115. of a microscope, 115. of a telescope, 115.

Mammoth Cave of Kentucky, 71.

Manganese dioxide, 46. chlorine made from, 238. oxygen made from, 46.

Marble, for carbon dioxide, 55.

Matches, 47. safety, 47-48.

Matching colors, 137.

Matter, conservation of, 58, 59.

Meat, 66. preservation of, 253.

Mechanical devices, 154, 155.

Melting, 39, 40.

Melting point, 40.

Melting substances without a definite melting point, 40.

Mercerized cotton, 218.

Mercury, barometer, 84. thermometer, 14-17.

Metals, electroplating, 317. preservation by paint, 253-254. veins deposited by precipitation, 72, 73. welding, 315.

Meter, gas, 93, 94.

Microörganisms, 132, 133.

Microscope, 115.

Milk, boiling point, 32. Pasteurized, 250.

Minerals, in foods, 62, 63. in water, 70, 71.

Mirrors, 108-112. distance of image behind mirror, 111. distance of object in front of mirror, 111. image a duplicate of object. 111.

Molding of glass, 40.

Molecule, 100-103.

Mordants, 247, 248, 249.

Morphine, 257.

Morse, telegraphic code, 324.

Motion, in sound, 266, 278, 280. in work, 156.

Motor, electric, 336. principle of, 333. street car, 337.

Mouth breathing, 50. cause of, 51.

Movable pulley, 167, 168.

Music, 278.

Musical instruments, percussion, 299. stringed, 284-295. wind, 295, 299.

Musical scale, 282.

Naphtha in gas engines, 185.

Naphthalene, 152.

Narcotics, 255.

Natural gas, 152.

Needle, magnetic, 328.

Negative, electrode, 308. photographic, 130.

Neutral substance, 222. and litmus, 222.

Neutralization, 222.

Niagara Falls, 176.

Nitrogen, 66. and bacteria, 263. and plant life, 261. in atmosphere, 261. in fertilizer, 262-265. in food, 66. preparation of, 261. properties of, 261.

Noise in music, 280.

Non-conductors, of electricity, 321-322. of heat, 25.

Nutcracker, as a lever, 162.

Oboe, 297.

Octave, 284.

Odors, 101.

Ohm, unit of resistance, 345.

Oil, gasoline, 149, 150. kerosene, 149, 150. lubricating, 174. olive, 16.

Orchestra grouping, 299.

Ore, 72.

Organ pipes, 297.

Overtones, 290-293.

Oxalic acid, 247, 248.

Oxidation, 45-59. and decay, 49. heat the result of, 49-52. in human body, 49, 53. of iron, 48.

Oxygen, 66. and bleaching, 239. and combustion, 45. and food, 66. and plants, 55. and the human body, 50. and water, 79, 80. in the atmosphere, 45. preparation of, 46.

Paint, as wood and metal preservatives, 253, 254. removal of stains, 243.

Paper making, 219.

Paraffin, 150, 321.

Pasteurized milk, 250.

Patent medicines, 257-260.

Peas, sources of nitrogen, 263.

Pelton wheel, 177.

Percussion instruments, 299.

Period of a body, 273.

Peroxide of hydrogen, 53, 252

Petrolatum, 150.

Petroleum, 149, 150.

Phonograph, 303-305.

Phosphorus, in fertilizer, 263, 264. in making nitrogen, 261. in matches, 47, 48. poisoning by, 47.

Photography, 127-131.

Photometer, 107.

Pianos, 284-292.

Pin wheel, 181.

Pitch of sound, 280, 281. cause of, 282. in wind instruments, 296-299.

Plane, inclined, 162-166.

Plants, and atmosphere, 55. and light, 131-132. and nitrogen, 261.

Plate developing, photographic, 128.

Pneumatic dispatch tube, 205.

Poles, magnetic, 330-332. of cell, 308.

Positive electrode, 308.

Potash, in fertilizer, 263-265.

Potassium chlorate and oxygen, 46. permanganate, 100. tartrate and Rochelle salt, 227.

Power, candle, 105-107. electric, 351. horse, 173, 351. sources of, 174, 175, 185. transmission by belts, 171. water, 176-180.

Precipitation, 72, 73.

Preservatives, food, 252. wood and metal, 253-254.

Pressure, atmospheric, 82-86. calculation of atmospheric, 83, 84. calculation of gas, 92, 93. calculation of water, 94. gauge, 92-94. of illuminating gas, 93. relation of pressure of gas to volume, 95, 96. water pressure, 208-211, 214-216. within the body, 86.

Primary colors, 135.

Print, photographic, 131.

Printing, color designs in cloth, 248, 249. electrotype, 317.

Prisms, 135. refraction through, 117.

Proteids, 66.

Pulleys, 166-169. applications of, 169.

Pump, 187-205. air, 201-205. force, 192, 193. lifting, 189-192.

Pupil of the eye, 122.

Pure food laws, bleaching, 242. preservatives, 252.

Purification of water, 77, 196.

Push button, 321.

Radiator, 19-21.

Railroads, grading of, 165-166.

Rain, 36, 37.

Rainbow, 134.

Rain water, 225.

Reflection, angle of, 110. of light, 109-112. of sound, 278, 279.

Refraction, angle of, 114. by atmosphere, 114. of light, 113. uses of, 115-116.

Relay, telegraph, 325.

Reservoir, 214. artificial, 211. construction of, 214-216. natural, 211.

Resistance, electrical, 312. internal, of cell, 343. unit of, 345.

Resonance, 276.

River, volume and value of, 180.

Roads, application of inclined plane to, 165-166.

Rochelle salt, 227, 231.

Rocks, effect of freezing water on, 42-43. water as a solvent, 71.

Rosin, obtained by distillation, 35.

Safety matches, 47-48.

Salicylic acid, 253.

Salt, 227-228.

Salts, 227. general properties, 227. in ocean, 227. smelling, 222.

Saturation of air, 37.

Scale, musical, 282.

Screw, and inclined plane, 166.

Seaweed, 265.

Seidlitz powder, 231.

Self-raising flour, 231.

Sewage, disposition of, 198-199. of camps, 196. source of revenue, 201.

Sewer gas, 57.

Silk, bleaching, 241. dyeing, 245-247.

Silver chloride, 127-131.

Simple colors, 138.

Simple substances, 103.

Siren, 280.

Smelling salts, 222.

Snow, 36-37.

Soap, 222-224. and hard water, 225. liquid, 223-224. preparation, 223.

Soda, baking, 227, 228-229. benzoate, 253. caustic, 218, 222, 223, 227. washing, 225, 226, 229.

Soda mints, 231.

Sodium, bicarbonate, 56, 227, 228, 230-231. carbonate, 228. chloride, 228.

Soil, deposited by streams, 73.

Solenoid, 318.

Solution, 70.

Soothing sirup, 258.

Sound, and motion, 266, 278. musical, 278. nature of, 266. reflection, 277. speed of, 271-272. transmission of, 267-271. velocity of, 271-272. waves, 272-274.

Sounder, telegraph, 324.

Sounding board, 277.

Sour milk in cooking, 230.

Specific heat, 28-29.

Spectrum, 134-135.

Speed, of sound, 271, 272.

Spontaneous combustion, 52.

Stains, removal of, 226, 243.

Standpipes, 212.

Starch, 65.

Steam, and work, 183-184. engine, 183-185. heat of vaporization, 32. heating by, 33. turbine, 183-184.

Steel, forging and annealing, 16.

Stoves, 18-19.

Streams, carriers of mud, 73. volume of, 179-180.

Street cars, electric, 337.

Stringed instruments, 284-295.

Strings, vibrating, 286-290.

Sugar, 16, 65. fermented by yeast, 234.

Sulphur, 66. as disinfectant, 251. in making sulphurous acid, 242.

Sulphuric acid, in bleaching, 240,241. in fire extinguisher, 55. in making of hydrogen, 80. in voltaic cell, 307.

Sulphurous acid, in bleaching, 242. preparation, 242.

Sun, energy derived from, 143-144. source of heat, 29-30.

Sunlight, 135. and bacteria, 133. and chemical action, 126-127.

Sympathetic vibrations, 274-277.

Tallow, 105, 148.

Tartar, cream of, 229.

Telegraph, 322. long distance, 327. relay, 325. sounder, 324.

Telephone, 350-351.

Temperature, 13-14. as measurement of heat present, 27. in detecting adulterants, 17. in forging steel, 16. in making sirups, 16. measurement of, 14-15.

Thermometer, 14-17. Centigrade, 15. Fahrenheit, 15.

Tinder box, 47.

Transmission, of light, 145-147. of sound, 267-271.

Tuning fork, 266, 273, 278, 290.

Turbine, steam, 183. water, 178.

Turpentine, and grease, 226. by distillation, 35.

Unleavened bread, 233.

Vacuum, sound in, 268.

Vapor, in atmosphere, 36-38.

Vaporization, heat of, 32.

Varnish, on candies, 253.

Vegetable matter, and coal, 30. and gas, 30. and oil, 30.

Veins, formation in rock, 72-73.

Velocity, of sound, 271-272.

Ventilation, 21-24, 54. need of, 38.

Vibration, of strings, 286-290. sympathetic, 274-277.

Viola, 295.

Violin, 295.

Violoncello, 295.

Vocal cords, 300.

Voice, 300.

Volt, 344.

Voltage, 345.

Voltaic cell, 306-308, 310.

Voltmeter, 344.

Volume, of a stream, 179-180. relation of pressure of a gas, 95-96.

Washing powders, 224-226. soda, 229.

Water, action in nature, 70-74. amount used daily per person, 181. and hydrogen, 79. and oxygen, 79, 80. as solvent, 70-71. boiling, 77. boiling point, 15. composition, 79-80. condensation, 33. dams and reservoirs, 214-216. density, 11. distilled, 34, 77. drinking, 75-77, 195-201. electrolysis, 79-80. evaporation, 33-34. expansion, 9-10, 41-42. filtration, 77. freezing, 40-41. hard, 225. heat of fusion, 40. impurities, 76-77. in atmosphere, 36-38. in food, 75. in human body, 75. in vegetables, 75. influence on climate, 29, 40. irrigation, 193-194. minerals in, 70-71. ocean, 265. power, 176-180. precipitates, 72, 73. pressure, 208-211, 214-216. purification, 77. rain, 225. running, value of, 178-180. source of, 78. steam, 32. waves, 145-147. weight, 208-209, 215. wells, 195-201. wheels, 176-180. work under, 203-205.

Water supply, and forests, 216-217. cost, 212-214. of city, 206-212, 217.

Watt, 351.

Waves, heat, 145-147. light, 145-147. sound, 268, 272-274. water, 145-147.

Weather, bureau, 87-91. forecasts, 38-39, 86-88. relation of water to, 29, 40.

Weather maps, 89-91.

Wedge, and inclined plane, 166.

Weight, of air, 86. of water, 208-209, 215.

Welding, by electricity, 315.

Wells, 195-201. drilled, 199. driven, 196-197.

Wheel and axle, 169-171. cogwheels, 170. windlass, 169.

Wheelbarrow as lever, 160-161.

White light, nature of, 135.

Wind instruments, 297-301.

Windlass, 169.

Windmill, 174-175, 180-182.

Winds, 24.

Wine, 232, 234.

Wood, as source of charcoal, 58. ashes in soap making, 223. in paper making, 219. preservation, 253-254.

Wool, bleaching, 241. dyeing, 245-247.

Work, 156-186. and steam, 183-184. and water, 176-180. conservation, 174-175. formula, 157. machines, 157-175. unit of, 172-173. waste, 173.

Woven designs in cloth, 249.

Yeast, 234-236. wild, 235-236.

Zinc, in galvanizing iron, 49. in making hydrogen, 80. in voltaic cell, 307-308.