They were made in imitation of Oriental stones, of which the supply was inadequate for the great demand of the first and second centuries A. D., and also as a matter of economy. Often in ancient times a quantity of fragments of hard semi-precious pebbles too small to be engraved were pulverized, and the sand or granulated mass was fused in crucibles just as glass is made. This process enabled many lovers of the art to possess examples in this cheaper artificial substance when the same subjects on real India stones were commanding exorbitant prices. Some of these gems are beautifully opalescent and iridescent. This iridescence, though so beautiful on the specimens of that kind, is only owing to chemical action on the paste gems during the centuries they have been buried in the earth. Interesting intaglios and cameos in enamel have withstood the wear of ages, and are in better condition; the imitations of red jasper are wonderful. SOMMERVILLE COLLECTION. [Illustration: 1183] [Illustration: 1244] [Illustration: 1288] ANTIQUE PASTES. Many intaglios in antique paste are representations in designs of ancient bronzes, of which we have no other trace except their mention by early historians. The most precious antique example in paste is the Portland Vase. It was discovered in the sixteenth century in a sarcophagus within the monument of the Emperor Alexander Severus and his mother, Julia Mamæa, on the Frascati road, about two miles and a half from Rome. It was long known as the Barberini Vase, having belonged to that family in Rome for two hundred years; thence it came to England in the last century, and after twice changing ownership, at the death of the Duchess of Portland, from whom it takes its name, it was sold to the Duke of Marlborough, and is now in the British Museum. It has been broken and mended. It is about ten inches high, and at the broadest part six inches in diameter. It was formed of paste, and afterward engraved. The paste is in imitation of onyx, in two strata, white upon blue, of an amethyst tinge; the figures are cut in relief on the lighter color, the blue forming the second plane or background. Though the antique paste cameos and intaglios are largely reproductions of subjects also found engraved on pietradura, we are indebted to this class of gems for many examples of ancient cameos and intaglios which we would otherwise never have seen; in fact, from the rare beauty of some specimens in paste, they never could have existed in any other material. Not only do both intaglios and cameos in antique paste present us with the choicest examples of miniature art, but the iridescence created on them by time frequently renders them the most beautiful specimens in a collection. [Illustration] MYTHOLOGICAL. Through the possession of these Pagan cameos and intaglios we have become heirs to the most thorough knowledge of Mythology.