and is perfectly opaque; whilst the upper surface is of white transparent glass. Between the two, is a very thin layer of gold-leaf—the whole being fused into one substance. This description of gilded Glass was, no doubt, high valued; and the perfect state in which it is found, affords a convincing proof that the art of Glass incrustation was, to a certain extent, known to the ancients. The pieces which have hitherto been met with are, for the most part, about an inch square, or of the same size in a diamond form.

During the reign of Nero, great improvements were made in Roman Glass. The perfectly clear Glass, which bore the nearest resemblance to crystal, was so highly valued, that Nero is stated to have given for two cups, of no extraordinary size, with two handles, 6000 sestertia, or nearly £50,000 sterling. The superior kinds of Glass were in such extensive use, in the time of Pliny, as to have almost superseded cups of gold and silver. Hence, the manufacture would appear to have been confined chiefly to articles of luxury—such as vessels of glass to imitate precious stones, intended for cutting by the lathe, by Roman artists, or Grecian artists resident in Rome, in the style of cameos in relief. In the British Museum are preserved many specimens of fragments of vases, and small pieces of white opaque enamel Glass, upon blue and amethyst transparent grounds, supporting the probability of this opinion. White crystal Glass, without lead, cut to imitate rock-crystal, was then known; although the introduction of lead into white glass was, till recently, considered to be of British origin.* (See PLATE 3, fig. 3.)