Tannin in clay, 25, 26, 41 Telluric water, 165 Temperature, resistance to, 119, 120 Tensile strength, 23, 45 Terra-cotta clays and shales, 5, 10, 12, 31, 46, 56, 63, 91, 104, 123, 124, 129, 166 Tertiary clays, 62 Texture, 112, 130 Thermal reactions, 146, 154, 158 Tiles, 1, 5, 57, 91, 101, 129 Titanium compounds, 121 Tourmaline, 76, 104 Transportation of clays, 49, 86, 98, 99, 100 Transported clays, 70 Triassic clays, 57, 112, 130 True clay, 144, 146, 149, 150, 160 Twisted ware, 114, 129, 131 Types of clay, 82 Ultimate analysis, 16, 144 Ultra-marine, clays for, 109 Underclays, 53, 117, 118 Uses of clay, 1, 165 Valuation of clay, 103, 109, 123, 126, 162, 165 Vegetable matter, 15, 119 Veins, 85 Viscosity, 152 Verifiable clays, 113, 156, 166 Vitrification, 15, 20, 37, 112, 113, 114, 156 Vitrification range, 38, 114, 115, 116, 129 Volcanoes, 85 Warp, 99 Warped ware, 114, 129, 131 Washing, 7, 79 Water, effect of, 74, 76, 81, 85, 86, 151 Water in clays, 15, 17, 29, 39, 45, 154 Wealden clay, 62 Weathering, 44, 74, 76, 79, 80, 97, 107, 165 White bricks, 68, 128 White clays, 70, 166 Wind, 86 Zeolites, 157 CAMBRIDGE: PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS End of Project Gutenberg's The Natural History of Clay, by Alfred B. Searle