Expansion, coefficient of thermal, 24, 25 F. Felspar, 40, 44 Fibres, glass, 245 silica, 245 Figured rolled plate glass, 87, 130 cutting of, 131 Finger-marks on lenses, 219 Fining of glass, 81 optical glass, 229 Fire-clay, action of, on glass, 6 for pots, 55 wetting up, 57 Fire-polish, 117 Flashed glass, 25, 199 Flint, 40 boro-silicate, 212 dense, 212, 246 densest, 212 extra dense, 212 glass, 7, 49, 78, 108, 211 light, 212 soda, 212 telescope, 215 Fluorite, refractive index of, 216 Fontainebleau, 38 Founding of optical glass, 227 Fourcault process, 174 Fresnel, 251 Furnace crowns, 60 gas, 63 Furnaces for bottle manufacture, 97 glass melting, 54, 62 optical glass, 225 plate glass, 133 rolled plate glass, 122 sheet glass, 151, 170 ports, 67 recuperative, 66, 156 regenerative, 66, 155 tank, 59, 69 economy of, 72 Fusion, process of, 73 temperature of glass, 5 Freezing of glass, 2 G. Gaslight, chimneys for, 23 Gas producers, 62, 64 Gatherer, 158 Gathering of glass, 85, 88, 158 Gauge tubes, 10, 18, 23, 26 Gems, artificial, 246 Ghosts, photographic, 16 Glauber’s salt, 43 Gold, colouring effect of, 185 Grinding plate glass, 137 Gypsum, 47 H. Hardened glass, 20 Hardness of glass, 21 tests for, 22 Heavy spar, 48 Henrivaux, 19 Hertz, 22 Hock-bottle colour, 195 Hohenbocka, 38 Hollow glass-ware, 108 Horse-shoe flame, 69 Hydrofluoric acid, action of, on glass, 12 Hygroscopic glass, alkali content of, 6 I. Indentation modulus, 22 Index, refractive, 216 Insulating properties of glass, 29 Iron, 96 colouring effect of, 196 oxidation of, in glass, 195 Irregularities caused by rolling, 86 J. Jena, 7, 10, 14, 26, 29, 203, 210, 213, 241 K. Kelp, 40 Kowalski, 19 L. Laboratory ware, 10, 23 Ladling glass, 85 rolled plate glass, 124 Lagre, 166 Lamp-chimneys, 110, 238 Lamp-work, 240, 244 Large vessels, production of, 105 Lead, 49, 183, 188 Lear for rolled plate glass, 127 sheet glass, 165 Leighton, 39 Lenses, cleaning of, 220 finger-marks on, 220 pressing small, 94 Light, action of, on glass, 15 Lighthouse glass, 178, 250 Lime, slaked, 45 Lime-stone, 46 Limited range of vitreous bodies, 4 Lippe, 38 Lynn, 39 M. Machines, bevelling, 145 double rolling, 130 grinding, 139 polishing, 141 Magnesia, 48, 186 Manganese, 15, 52, 80 Mangin mirrors, 252 Marver, 111 Massive glass, 249 Mechanical properties of glass, 18 Metal, attachment of, to glass, 26 Minerals, crystalline, 217 Mirrors, 145 searchlight, 251 Mixing of materials, 73 Moulds for glass-blowing, 90, 110, 116 pressed glass, 119 Muffled glass, 172 Muranese glass, 123 N.