Iridium, 129 Iron, 18, 262, 294 Iron pyrites, 18 Italy, 249 Jablochkov: electric candle of, 117 Jamaica, 19 Jandus, 118, 122 Japan: 19; use of oil in, 30; 281 Jerusalem, 43 Jews: artificial light among, 40 _Journal_, Paris, quoted, 210-212 Kerosene: 57; weight of, lumens, 60; 62, 187, 233 Kitson, platinum-gauze mantle applied by, 61 Laboratories: achievements of, 137 Lamps: 16, 25; Roman, 30; 31; invention of safety, 33; ancient funereal, 39; sacred, of antiquity, 41; ceremonial, 44; scientific development of oil, 51 _et seq._; Holliday, 55; Carcel, 54, 55; Franchot's moderator, 55; gasolene, 55; development of, in Germany, 56; air pressure, 61; supremacy of oil, ends, 62; Bowditch's, 77, 78; 80, 97; mercury-arc, 126; electric incandescent filament, 127 _et seq._; gem, 132; tungsten, 133 _et seq._; luminous efficiency (table) of incandescent filament, 141; 299; in home, 328-333 Lange, 167 Lard-oil, 51 Lavoisier, 195 Lead, 262, 294 Le Bon, 72 "Legend of Montrose, The," Scott, cited on primitive lighting, 27 Leigh, Edmund, quoted, 226 Lenses, 20, 171 _et seq._ Libanius, quoted, 153, 154 Liberty, Statue of, 301, 302, 303 Libraries, 9 Light: relation of artificial, to progress, 3 _et seq._; as a civilizing agency, 3-14; primitive man and artificial, 4; Milton, quoted on importance of, 5; artificial, and science, 7; artificial, and industrial development, 8; Maeterlinck's tribute to, 9; Lincoln's debt to artificial, 9; symbolism of, 9, 10; therapy, 10; in war, 11; adaptations of, 12; 13; mythical origin of artificial, 16; earliest source of, 16; production of, in stone age, 18; matches as source of, 21; animals as, sources, 24, 25; primitive sources of, 24-37; evolution of artificial, sources, 24-37; development, 28 _et seq._; early outdoor use of artificial, 28; Roman uses of artificial, 30; beginning of scientific, 33, 34; candles as modern, source, 36, 37; symbolism and religious uses of, 38 _et seq._; Bible cited on artificial, 42-44; in relation to worship, 43, 45, 46; Argand's contribution to, 53, 54; coal as, source, 55; early uses of gas as, source, 63 _et seq._; as a public utility, 70; first installation of industrial gas, 72; science of, production, 80 _et seq._; causes of, radiation, 80, 81; 83; lime, 84; electric, 89 _et seq._; principle of, production, 90, 91; sources, 93; various gas-burners', supply, 95; relative efficiency of, sources, 95, 96; in the home, 97; influence of, upon science, invention, and commerce, 97 _et seq._; yield of acetylene, 106, 107; electric, 109; influence of gas upon development of artificial, 110; development of artificial, 111 _et seq._; efforts to improve color of mercury-arc, 125; electric-incandescent-filament, 127 _et seq._; effect of tungsten, upon, 133 _et seq._; of the future, 143-152; in warfare, 178-193; signaling, 194-207;