Pliny ascribes the discovery of glass to some Phœnician sailors accidently lighting a fire on the sea-shore; but if an effect of chance, the secret is more likely to have been arrived at in Egypt, where natron (or subcarbonate of soda) abounded, than by the sea side; and if the Phœnicians really were the first to discover it on the _Syrian_ coast, this would prove their migration from the Persian Gulf to have happened at a very remote period. Glass was certainly one of the great exports of the Phœnicians; who traded in beads, bottles, and other objects of that material, as well as various manufactures, made either in their own or in other countries: but Egypt was always famed for its manufacture; a peculiar kind of earth was found near Alexandria, without which, Strabo says, "it was impossible to make certain kinds of glass of many colors, and of a brilliant quality," and some vases, presented by an Egyptian priest to the Emperor Hadrian, were considered so curious and valuable that they were only used on grand occasions. Glass bottles, of various colors, were eagerly bought from Egypt, and exported into other countries; and the manufacture as well as the patterns of many of those found in Greece, Etruria, and Rome, show that they were of Egyptian work; and though imitated in Italy and Greece, the original art was borrowed from the workmen of the Nile. Such, too, was their skill in making glass, and in the mode of staining it of various hues, that they counterfeited with success the emerald, the amethyst, and other precious stones; and even arrived at an excellence in the art of introducing numerous colors into the same vase, to which our European workmen, in spite of their improvements in many branches of this manufacture, are still unable to attain. A few years ago the glass-makers of Venice made several attempts to imitate the variety of colors found in antique cups; but as the component parts were of different densities, they did not all cool, or set, at the same rapidity, and the vase was unsound. And it is only by making an inner foundation of one color, to which those of the outer surface are afterwards added, that they have been able to produce their many-colored vases; some of which were sent to the Great Exhibition of 1851.