Abstract The artificial blue pigment used in Egypt from the IVth Dynasty and also used widely during the time of the Roman Empire has been investigated by many chemists, including Sir Humphry Davy, Vauquelin, H. de Fontenay, Darcet, F. Fouqué, and Dr. W. J. Russell, F. R. S., but the exact nature of the compound and the manner of its formation do not yet seem to have been finally decided. According to Vitruvius, the blue was made by heating together a mixture of copper filings, sand, and soda in a furnace. A great deal of information has been obtained as to the actual furnaces used and the methods of heating which will be found in “Notes on Egyptian Colours” by F. C. J. Spurrell, reprinted from the ‘Archæological Journal,’ September, 1895.