Index 



389 



Sky, reason why blue, 169; why red 

 at sunset, 170. 



Smoke, consistency of, 318-319. 



Snow, 275 ; formation of, 285-286 



Snowflakes, 97, 286*. 



Soap, how made, 357-358. 



Soda water, how made, 365-366. 



Sodium, experiment with, 304. 



Softening due to oil or water, 290-292. 



Soil, litmus test of, 359. 



Solution, denned, 261 ; difference 

 between emulsion and, 263; a 

 mixture and not a compound, 309; 

 chemical change helped by, 349. 



Sound, cause of, 174; rate of speed, 

 181-182; action of, in echoes, 183- 

 185*; pitch of, 185-188. 



Sour milk, litmus test of, 359; neu- 

 tralization of, by baking soda, 362. 



Sourness, taste of, caused by acids, 



353, 354-355- 



Spectroscope, use of the, 172. 

 Spectrum, the, 172. 

 Spring water, carbon dioxid in, 366. 

 Stability, 29-34. 

 Starch, iodine test for, 373-374. 

 Stars, twinkling of, 141 ; how to tell 



of what made, 171-172. 

 Static electricity, 196-202*. 

 Steam, reason for force exerted by, 



no; geysers and volcanoes caused 



by, no; real, not visible, 112 n. 

 Steel, generally an alloy, 310. 

 Stereopticons, lenses of, 148. 

 Storage battery, 206, 207*; action 



of electricity in, 339. 

 Stoves, electric, 230, 232. 

 Street car, electric motor of, 255- 



257- 



Suction pump, 19*. 

 Sugar, making of, by plants, 332-333 ; 



litmus test of, 359. 

 Sulfur, an element, 300. 

 Sulfuric acid, action of, on cloth, 354; 



litmus test of, 359. 

 Sun, radiation of heat and light from 



the, 122-128; how to tell of what 



made, 171-172. 



Sunbeams, explanation of, 131. 

 Sweat glands, function of, 291. 



Tanning, process of, 327. 



Telegraph apparatus, 247-252*, 380- 



381*. 



Telegraph code, 253. 

 Telephone, working of, 253-255. 

 Telescopes, 156*, 157 ; how made, 157; 



reflecting, 157. 

 Temperature, finding the, by reading 



a thermometer, 90-91. 

 Thermometer, the, 89*~9i*. 

 Thermos bottle, how made, 126-127*. 

 Thunder, cause of, 200-201. 

 Tin, an element, 300. 

 Tin salt, poisonous, 353. 

 Toasters, electric, 230, 232. 

 Tomatoes, use of soda to neutralize 



acid of, 362-363. 

 Tungsten, in incandescent lamps, 



231. 

 Tuning-fork experiments, 181*, 186- 



187* 

 Twinkling of stars, cause of, 141. 



"Up," meaning of word, 4. 



Vacuum, denned, 1 1 ; reason for, in 

 electric lamp, 12*, 317; use of, in 

 manufacture of thermos bottles, 

 1 26-1 2 7* ; impossibility of producing 

 sound in, 176-177. 



Valves, safety, on boilers, 347. 



Vaseline, production of, 114. 



Vibrations, of air, 174-181*; pitch due 

 to rapidity of, 186. 



Vinegar, litmus test of, 359; neu- 

 tralization of lye by, 363. 



Violin, tuning of, 187. 



Volcanoes, cause of, no; explosions 

 and, 346*. 



Volume, elasticity of, 86-87. 



Washing soda, a common base, 356; 

 litmus test of, 359. 



Water, seeks its own level, 6-10; 

 gurgling of, when poured from bot- 

 tle, 13 ; experiment with, to show 

 centrifugal force, 73~745 used for 

 making thermometer, 9o*-92 ; ex- 

 pansion of, when frozen, 98 ; evapo- 

 ration of, 100-106; action of, in 



