Quartz, behaviour in the kiln, 39, 42, 43 cavities in, 40, 41 characters of, 39 imperishable, 40 micro-structure of, 128 occurrence in brick-earths, 40 under blowpipe, 72 vein, 40 Race: concretions of carbonate of lime, commonly found in brick-earths in brick-earths, 50 Rainfall and the durability of bricks, 108 “Rattling” tests, 148 Reading mottled clay, 18 Red brick, 100 Red brick clay, 86 Red bricks, colouring matter of, 45 Reducing flame, 65 Refractory minerals (see Calcite, Dolomite, Magnesite, Quartz, etc.). Reindeer remains, found in brick-earth, 2, 3 Reptiles, fossil, 25 Rhinoceros’ remains, found in brick-earth, 2, 3 River deposits, typical section, 10, 11 River terraces, brick-earths of, 12, 13 Rock crystal, 40 Rock salt, under blow-pipe, 74 Ruabon bricks and terra-cotta, 84 terra-cotta, 116 Rubbers, 29, 86 Saarbrücken “iron bricks,” 92 Salt, a powerful flux, 57 behaviour in the kiln, 57 glazing, 57 in brick-earths, 25, 27, 56 in quartz crystals, 41 under blow-pipe, 74 Schorl, 40 Scum, 110 Sea-shore, brick-earths from the, 25 Selenite, 54, 131 under blow-pipe, 74 Septaria: tabular or rounded concretions of argillaceous limestone, commonly found in clays Septaria, 51 Shrinkage of brick-earth in the kiln, 85 Silica, behaviour in the kiln, 28 group of minerals, 39 Slates, chemical composition of, 87 débris for brickmaking, 87 refuse, 47 used in brickmaking, 47 Snails, found in brick-earth, 4 Specific gravity of bricks, 146, 149 Stacking in the kiln, 97 Staffordshire blue bricks, 99 Stibnite, 68, 70 Stocks, London, 140 Stoneware, earths for making, 21 Stourbridge bricks, 82 Strength of bricks, 136 Styrian magnesite, 56 Swiss brick-earths, 89 Temperature and weathering of bricks, 115 in kilns, 98 Terra-cotta earths, 19, 30 earth, chemical composition of, 84 expansion of in weathering, 115 Ruabon, 116 Tests for bricks (see strength, absorption, specific gravity, chemical composition, micro-structure, etc.). Thames, mineral salts in solution in the, 7 Thames Valley brick-earths, 1, 2, 3, 4, 5 Tuscany, infusorial earth, 92 Variable character of brick-earths, 10 Variability in character of marine brick-earths, 23, 24 of estuarine brick-earths, 21 of lacustrine brick-earths, 17 Vegetable growth on bricks, 113 Vein quartz, 40 Volcanic ejectamenta for brickmaking, 93 Wales, fire-clays of, 81 Warping, 98 “Weathering” agents which affect bricks, 6 Weathering of brick-earths, 27 White bricks, 100 Yellow bricks, 101 [Illustration] Transcriber’s Notes As Footnote 1 states, technical terms are explained in the Index at the end of the book.