The Japanese cloisonné with its literal treatment of natural forms, and the painted enamel portraits of Francis I. and contemporary princes by Leonard Limousin, clever as they undoubtedly are, lack the depth and purity of colour obtained by the early methods. Frequently, however, the Penicauds, Nardou, and Jean I. and II. obtained some richness in the painted enamels by the use of “_Paillons_” or pieces of metallic foil which were afterwards flooded with translucent enamel. [Illustration: GLASS. Plate 30. ] GLASS. The purity of glass, its adaptability to colour, and its remarkable ductility while hot for blowing, twisting or drawing into threads, differentiates it from all other materials and methods of treatment. Its tradition dates from the remote past, for glass-blowing is represented on the tombs at Thebes, B.C. 2500. It was also used in Egypt for vitreous pastes for bronze and gold cloisonné jewellery, and for the small bottles or Stibium, with chevron patterns, in yellow, turquoise and white on a coloured ground. Similar patterns, colours and forms were used by Phœnicia and her colonies, the usual forms being the Alabastra and Amphorae. Many remains of bowls were found in Assyria, one (now in the British museum) of transparent green glass, having the name of Sargon, B.C. 722. Greece seems to have imported most of her glass from Phœnicia, but the Romans carried on the tradition, producing fine MOSAIC or MILLEFIORI. This was made by fusing rods of white and coloured glass together, then drawing it out to fine threads and slicing it transversely; the section is then placed in a mould and a bubble blown, uniting the mosaic, which is then blown into various shapes. The Romans also used the interlacing of white and coloured rods called LATICINIO, but they excelled in the CAMEO GLASS, of which the Portland vase is the finest known example. This vase is of dark blue glass, covered with white opaque glass, which was ground away with the wheel, leaving the figures in delicate relief. It was found in 1644 in the sarcophagus of Alexander Severus, A.D. 325, the subject of its relief being the myth of Peleus and Thetis. Another Roman example of cameo glass in the British museum is the Auldjo vase or Oinochoè with beautiful reliefs of vine leaves. Frequently these reliefs were blown or pressed into moulds, and a good example of this treatment is in the South Kensington museum (fig. 6). The tradition then declined until the 14th century, when the Venetians in the island of Murano, perfected the art of glass making.