66; early views of, 6 f.; Franklin’s theory of, 14, 20, 24; growth of theories of, 10 f.; ion of, 28; and light, 232; and matter, 186; proof of atomic nature of, 66, 131; structure of, 3, 4; two-fluid theory, 13 Electrolysis, 27, 28, 43 Electrolytic laws, 25 Electromagnetic theory of mass, 20, 183, 187; conflict with, 212 Electron, 4, 26, 77, 261; basis of all static charges, 72; early values of, 27-63; energy of, 239, 250, 282; mass of, 27; origin of the word, 23; positive and negative equal, 82, 83, 182, 208; radius of, 183 f., 188; speed of, 191; theory of, 11, 21, 24 Electronic energy, 245 Electronic orbits of atoms, 221, 222 Electrons: emission of, 233, 236; number of, in atom, 193; number of free positive, in nucleus, 277, 281 Elements, with atomic numbers and weights, and chemical positions, 286 : for cathode rays, 42; value of, in electrolysis, 27, 30; value of, in exhausted tubes, 43; for negative and positive ions, 43; Bucherer’s value of, 214 Emission energy of electron, 236, 250 f.; explosive, 253; from light, 251 Epstein theory of orbit, 219, 220 Ether, 16, 26; theory, 232, 235 Ether-stress theory, 17 f.; objections to, 248 Ether-string theory, Thomson’s, 236, 237, 248, 249 Faraday constant, 120 Faraday’s laws, 15, 19, 22, 25 Faraday lines, 237 Faraday-Maxwell theory, 17 Franklin theory, 20 Gamma rays, 232, 232 Gaseous conduction, nature of, 32 Gases: electrical properties of, 46; ionization of, 123; gases, quantitative measurements in, 147 Gram molecule, volume of in gases, 30, 31 Grating: molecular, 197; spacing, 261 Greek philosophy, 1, 2, 9 f., 232 , value of, 117, 212, 213, 242, 245, 261 [Pg 292] Hipp chronoscope, 74 “Hot spark,” 143, 220 Ion, 28, 29; diffusion coefficient of, 36, 262; gaseous and electrolytic, 34; isolation of, 67; mobility of, 35, 36 f., 39, 262; positive and negative, 38, 48; univalent, in electrolysis, 34, 39 Ionic charge, 29, 39, 45, 47, 176; elementary, 76; mobility, 264 Ionization: by rays, 139 f., 144; by -rays, 138, 144; by ether waves, 134, 144; gaseous and electrolytic, 39; mechanism of gaseous, 125; oil-drop experiments in, 127, 141; by X-rays and radium rays, 125, 134 Kinetic energy: of atom, 194, 273; of light, 239; of translation of molecule, 261 Kinetic theory, 8, 31, 49, 157; of gases, 145, 268 Lenard’s trigger theory, 251 Light-quantas, 244, 256 Mass, electrical theory of, 185, 188; of hydrogen atom, 261; variation of with speed, 188 Mass of charge on sphere of radius , 272 Maxwell-Boltzmann law, 81 Maxwell distribution law, 151, 275 f.; theory, 24 Mean free path of a gas molecule, 8, 183, 275 Mean free path of a negative electron, 191 Measurements, exact, 58, 65 Molecular cross-section, 275 Molecule: diameter of, 215; of gas, 261; kinetic energy of