Figure stone, description and uses of, 84 Filtering stone, of what made, 233 Fire damp in coal─mines, what it is, how produced, &c., 19, 153 Flint, description and uses of, 53, 54 ——, gun─flints, how made, 54 Florence marble, description and use of, 115 Fluat of lime, 119 Fluats, 13 Fluoric acid, what it is, 13 —— ——, how to etch on glass by means of, 120 —— ——, mode of obtaining, 120 Fluor spar, description and properties of, 119 —— ——, how manufactured, and the uses of, 119 Flux, white, of what made, 137 ——, black, 137 Freestone, description and uses of, 233 French chalk, description and uses of, 92 Fuller’s earth, description and use of, 87 Fulminating powder, 176 Fulminating silver, extraordinary properties of, 182 Fumigating of rooms, how effected, 133 Fur in tea kettles, how formed there, 114 G. Galena, what it is, 203 Gangue, in mining, what it is, 4 Garnet, precious, where found, how cut, and value of, 42, 43 –– ——, how set, and uses of, 42 ——, common, 43 ——, Syrian and pyrope, 43 Gas, what it is, 10 Gas lights, history and uses of, 156 —— ——, how produced, 156 –– ——, how exhibited on a small scale, 156 Gems, engraving, cutting, and value of, 21─23 ——, imitations of, 22 Giant’s causeway, account of, 95 Gilding on iron or copper, how performed, 172 —— in or─moulu, what it is, 172 —— on silver, how performed, 172 —— on the edges of tea─cups, 173 —— wax, how made, and use of, 172 ——, ancient mode of, 172 ——, on wood, 172 Glass, how made, 55 ——, bottles, how made, 55 ——, window and plate, how made, 55, 56 ——, annealing of, the use of, 56 ——, how to etch on, 120 ——, Muscovy. See Mica. Glauber salt, description of, how obtained, and uses of, 123 —— ——, pleasing experiment with, 134 Glimmer. See Mica. Glucine, 16 Gneiss, 226 Gold, description and properties of, 167, 168 ——, how obtained from mines in America and Europe, 168 ——, found in Ireland and Scotland, 168, 169 ——, mode of extracting from the ore, 169 ——, value and uses of, 170 ——, coinage or sterling gold; and gold of the new standard, 170 ——, description of the stamps on gold plate, 170 ——, how alloyed, 170 ——, coinage gold of Portugal, America, France, Spain, Holland, and Morocco, 170 ——, trinket and pale gold, how alloyed, 170 ——, ductility and tenacity of, 170 Gold leaf, how beaten, 171 Gold wire, 173 Gold thread and lace, what they are, 173 Gold powder for painting, how made, 173 ——, Dutch, how made, 187 Gold─beaters’ skin, how made, and uses of, 171 Granite, description and uses of, 225 ——, various kinds of, 225 Goulard, of what made, 207 Grey─wacka, 232 Grindstones, of what made, 234 Gritstone, description and uses of, 233 Gun─barrels, how browned, 141 Gun─flints, how made, and how to choose, 54 Gunpowder, how made, 137 Gypsum. See Alabaster. ——, fibrous, description and uses of, 118 H.