My friend M. Landerer, Professor of Chemistry in Athens, who has carefully examined the colours of the Trojan antiquities, writes to me as follows:—“In the first place, as to the vessels themselves, some have been turned upon a potter’s wheel, some have been moulded by the hand. Their ground-colour varies according to the nature of the clay. I find some of them made of black, deep-brown, red, yellowish, and ashy-grey clay. All of these kinds of clay, which the Trojan potters used for their ware, consist of clay containing oxide of iron and silica (argile silicieuse ferrugineuse), and, according to the stronger or weaker mode of burning, the oxide of iron in the clay became more or less oxidised: thus the black, brown, red, yellow, or grey colour is explained by the oxidation of the iron. The beautiful black gloss of the vessels found upon the native soil, at a depth of 46 feet, does not contain any oxide of lead, but consists of coal-black (Kohlenschwarz),[69] which was melted together with the clay and penetrated into its pores. This can be explained by the clay vessels having been placed in slow furnaces in which resinous wood was burnt, and where there was consequently dense smoke, which descended upon the earthenware in the form of the finest powder and was likewise burnt into the clay. It is also possible, but by no means probable, that they used a black pitch or asphalt, which was dissolved in oil of turpentine; perhaps they used liquid pitch, and painted the vessels with it. The burning of these would likewise produce coal-black, which in later times was called the Atramentum indelibile of Apelles. This is the manner in which colour and gloss were given to Hellenic terra-cottas.
