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 Phoenicia 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 Phoenicia, 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.

The earliest examples of Venetian Glass were massive, richly gilt and enamelled in colours; one fine example in the British museum is signed by its maker, “Magister Aldrevandini.” In the 15th and 16th centuries the most delicate and beautiful blown glass was made, often uncoloured and with enrichments of knots and wings in blown and shaped blue glass. The Venetians used with equal skill all the old methods of glassmaking; the Millefiori; the Laticinio or threads of opaque white enclosing pattern; Reticelli, a network of white lines enclosing at the intersections a bubble of air; and the beautiful Vitro di Trina, filigree or lace glass, formed by canes or threads of white or coloured glass being placed in a mould, a bubble being then blown in, and the glass afterwards taken from the mould and blown or twisted to the shape required. The artistic bronze mirrors of ancient and mediÆval times now give way to the glass mirrors of the Venetians, A.D. 1500.