YELLOW EARTH COLOURS 127 The Ochres 128 Calcining (Burning) Ochre 132 Ochres from Various Deposits 136 Artificial Ochres 138 Ochres as By-products 146 CHAPTER VI RED EARTH COLOURS 151 Bole 152 Native Ferric Oxide as a Pigment 154 Iron Glance 154 Hematite 155 Raddle 155 Burnt Ferric Oxide and Ochres 158 (_a_) Burning in the Muffle 158 (_b_) Caput Mortuum, Colcothar 160 (_c_) Calcining Ferric Oxide 161 Ferric Oxide Pigments from Alum Sludge 164 CHAPTER VII BROWN EARTH COLOURS 168 Terra di Siena 168 True Umber 170 Cologne Earth (Cologne Umber) 173 Asphaltum Brown (Bitumen) 174 CHAPTER VIII GREEN EARTH COLOURS 176 Green Earth, or Celadon Green 176 Artificial Green Earth (Green Ochre) 180 Malachite Green 181 CHAPTER IX BLUE EARTH COLOURS 183 Malachite Blue (Lazulite) 183 Vivianite or Blue Ochre 184 CHAPTER X BLACK EARTH COLOURS 185 Graphite 185 Black Chalk 194 CHAPTER XI THE COMMERCIAL NOMENCLATURE OF THE EARTH COLOURS 197 White Earth Colours 198 Yellow Earth Colours 200 Red Earth Colours 200 Brown Earth Colours 200 Green Earth Colours 201 Blue Earth Colours 202 Grey Earth Colours 202 Black Earth Colours 202 INDEX 203 EARTH COLOURS CHAPTER I INTRODUCTORY