In order to bring some kind of order into the various names which are applied to the earth colours, a list of those in current use is appended. Many of these names, it may be stated, have been selected in a purely arbitrary manner, some manufacturers, for instance, selling ordinary chalk under a variety of foreign names, for the purpose of thereby obtaining higher prices. These borrowed names would seem to be superfluous, to say the least. Pure and properly levigated chalk is the same article everywhere, whether prepared from English, French or German limestone; and in all cases the simple name, “chalk,” with an explanatory “single,” “double,” or “triple” levigated, should be quite sufficient. In the case of earth colours that are really obtained of special quality in certain localities, such as terra di Siena, green earth from Verona, or the like, the corresponding name might be retained, even if the pigment did not originate from the locality in question, as a generic term for a pigment possessing certain properties and of a certain composition. In the following classification, the names of the earth colours are given in accordance with their colour and chemical composition. WHITE EARTH COLOURS _Carbonate of Lime_: Chalk; levigated chalk; Vienna white; Spanish white; marble white; artists’ white; Bougival white; Champagne chalk; Paris chalk; Cologne chalk; Mountain chalk; craie; blanc minéral; Blanc de Champagne; Blanc de Meudon; Blanc de Bougival; Blanc de Troyes; Blanc d’Orleans; Blanc de Rouen; Blanc de Briançon. _Basic Carbonate of Lime_: Vienna white; Vienna lime; pearl white; whiting; Blanc de chaux; Blanc de Vienne. _Note._--The calcareous marls, consisting of carbonate of lime and clay, are also frequently sold under the above names, the same being the case with gypsum. _Silicate of Alumina_: White earth; pipeclay; Dutch white; Cologne earth; terre d’Argile; Argile blanc; Terre blanche. _Silicate of Magnesia_ (mineralogically, talc and soapstone): Talc; Venetian earth; French chalk; Venetian white; glossy white; feather white; shale white; face-powder white; Blanc de Venise; Blanc d’Espagne; Blanc de fard. _Note._--Fine grades of white lead are also sold as Venetian white, Spanish white and shale white; but can easily be recognised by their weight. The term “prepared” white, frequently applied to earth colours in the trade, usually indicates that the material in question has been either levigated, ground or burnt--in short, put through some kind of preparatory treatment--and is therefore in frequent use for all the colours. _Barium sulphate_: Heavy spar; barytes; heavy earth; mineral white. _Precipitated colours_: Permanent white; blanc fixe. YELLOW EARTH COLOURS _Ferric hydroxide_, with admixtures of ferric oxide, clay, lime, ferric silicate, basic ferric sulphate, etc.