----, brown, 174, 175 Augite, 179 Azurite, 33 Ball Mills, 55–56 Barium carbonate, 20 ---- sulphate. _See_ Barytes. Barytes, 19, 20, 119–122 ----, artificial, 133 ----, correcting colour of, 121 ----, detecting, in white lead, 120 ----, low covering power of, 121 Black chalk, 38 ---- earth colours, 185–196 ---- ----, trade names of, 202 ---- earths, 6, 38–39 ---- schist, 38 Bitumen, 174, 175 Blanc fixe, 19 Blue earth colours, 183–184 ---- ----, trade names of, 202 ---- earths, 4, 33–36 Bole, 31, 32, 152–154 Bone breccia, 13 Brown coal, pigments from, 175 ---- earth colours, 168–175 ---- ----, trade names of, 200 ---- earths, 5, 36–38 Calcareous marl, 110, 111 ---- tuff, 12 Calcining, 81 ---- Ferric oxide, 161–164 ---- furnaces. _See_ Furnaces. ---- lime, 88–90 ---- ochre, 132–136 Calcite, 11, 12, 14, 15 Calcium carbonate, 12, 14, 15, 16 ---- ----, action of acids on, 15 ---- hydroxide, 16 ---- sulphate. _See_ Gypsum. Calc sinter, 12 ---- spar. _See_ Calcite. Caledonian brown, 36 Cappagh brown, 36 Caput mortuum. _See_ Colcothar. Carbon brown, 37 ---- in limestone, 16 Cassel brown, 37, 38, 174 Celadon green. _See_ Green earth. Chalk, 13 ----, black, 194–196 ----, colour of, 103 ----, correcting colour of, 104, 105, 106 ----, covering power of, 106 ----, grinding, 101 ----, impurities in, 103, 104 ----, precipitated, 107–109 ----, preparation and properties of, 98–106 Classification of earth colours, 4–8 Clay, 21–23 Clay, formation of, 113 ----, impurities in, 114–119 ---- in ochre, 128 ----, levigating, 114–117 Colcothar, 160, 161, 162 Cologne earth, 173, 174 Commercial nomenclature of earth colours, 197–202 Crushers and Breakers, 43–45 Crushing, 77–80 ---- machinery, 43–60 Disintegrators, 58–60 Distemper, weatherproof, 94 Dolomite, 18 Draining and Drying, 66–77 Drying appliances, 73–77 Dyestuffs for improving earth colours, 85 Edge runners, 48–55 English red, 160 Ferric hydroxide in ochre, 128–132 ---- oxide, artificial ochre from, 143–144 ---- ---- as by-product, 30 ---- ----, burnt, 158–164 ---- ----, calcining, 161–164 ---- ---- in lime, detection of, 91 ---- ----, native, as pigment, 154 ---- ---- pigments from alum sludge, 164–167 ---- ----, range of colours, 29 ---- ---- shading, 28 ---- ----, violet shades from, 164 Ferrous sulphate, artificial ochre from, 139–143, 146–148 Filter-cloths, cleaning, 72 Filter-presses, 70–73 Furnaces, calcining, 158, 162, 163, 166 Granulator, 43 Graphite, 38, 39, 185–194 ---- as a lubricant, 194 ---- as anticorrosive, 194 Graphite in the manufacture of lead pencils, 191–193 ---- for crucibles, 193 ----, refining, 189–192 Green earth, 176–180 ---- ----, artificial, 180