Blocks, fire-clay, 58 tank, 59 Blower, sheet glass, 158 Blower’s chair, 111 Blowing glass, 89 holes, 91, 161, 189 sheet glass, 161 Blown glass, decoration of, 114 plate glass, 171 Bohemian glass, 109, 240 Boiling up, 81 Bottles, annealing of, 103 blowing, improvements in, 99 machines, 100 colour of, 96 manufacture, furnace for, 97 moulds for blowing, 98 production of, by hand, 98 raw materials for, 95 strength of, 18 Boric acid, 11 Boron, 186 Boro-silicate crown, 212 Boucher’s bottle-blowing machine, 101 Bricks, fire-clay, 58 silica, 60 Bubbles in optical glass, 230 removal of, 81 Burning, pots, 58 C. Cadmium, 186 Calcium carbonate, 46 oxide, 45, 186 sulphate, 47 Carbon, 53, 79, 186 Carbonate of soda, 41 Carbonic acid, action of, on glass, 12 Carboys, blowing of, 104 Casting plate glass, 132 Chair, glass-blower’s, 111 Chalk, 46 Chamotte, 57 Chance, 211 Charcoal, 42, 58, 79 Charging furnaces, 75 Chemical behaviour of glass, 6 composition of glass, 5 of optical glass, 217 reactions during fusion, 76 Chilled glass, 247 Chimneys, gaslight, 23 lamp, 238 Chromium, colouring effect of, 190 Cleaning of lenses, 220 Coal, anthracite, 42, 53, 79 Cobalt, colouring effect of, 197 Coke, 42, 53, 79 Colour of ancient windows, 16 glass, 32 theory of, 181 optical glass, 208 sheet glass, 167 Coloured blown glass, 113 glass, 178 technical uses of, 203 Combustion tubing, 7, 241 Compressed air for glass blowing, 91, 105, 117 Conductivity, electrical, of glass, 30 thermal, of glass, 24, 29 Copper, colouring effect of, 184 ruby, 184, 188, 198 Corrosion of glass, 11 Covered pots, 56, 109 Crown, boro-silicate, 219 glass, 175, 211 hard, 212, 219 soft, 212 telescope, 215 Crowns, furnace, 60 Crucibles, manufacture of, 56 for glass melting, 54 Crushing strength of glass, 19 Cryolite, 52 Crystallisation of glass, 3 Crystals, mineral, 218 Cullet, 74 for optical glass, 224 Cutting rolled plate glass, 128 Cylinders, sheet glass, 161, 171 D. Decolourisation of glass, 52, 188, 190, 193, 197 Decoration of blown glass, 114 Defects in rolled plate glass, 129 sheet glass, 166 Definition of glass, 1 De la Bastie, 248 Devitrification, 3, 11 Diamond, refractive index of, 216 Dimming of glass surfaces, 12 Dinas bricks, 61 Dipping of sheet glass, 166 Dispersion of optical glass, 209 partial, 214 Double refraction in optical glass, 221 rolling machine, 130 Drawing tubes, 239 Ductility of glass, 20 Durability of glass, tests for, 14 Dust, action of, on lenses, 220 glass, 245 E. Elasticity of glass, 20, 24 Electrical properties of glass, 29 Epinal, 39 Etching of glass, 12