358 



INDEX 



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 con- 

 sumed, 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, 16C. 

 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, SS, 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. 



anfl 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. 



