The glass-making art in Italy does not date earlier than the commencement of the Roman empire, importations from Sidon and Alexandria having previously supplied the want of native manufacture; but there is ample evidence of its extensive manufacture at that period, having been introduced in the days of the Ptolemies, large plates being used for incrusting chambers, vitrece econerm ; and hollow columns made of this material, with lamps inside, were used to illumine the public theaters. As early as 58 B.C., the theater of Scaurus had been decorated with mirrors or glass plates, disposed on the walls. Glass was also used for paving, and for the blue and green tesser? of mosaics (see Mosxic). Window-glass does not appear till about the 3d c. A.D.; the houses at Hercu laneum, destroyed in the reign of Titus, being glazed with talc, and some doubt remain ing as to the use of glass for this purpose at Pompeii. Lactautius in the 3d e. A.D.; St. Jerome, 422 A.D., mention glass windows. Older windows of this material are said to have been found at Ficulnea, and even in London. Under the Romans, colored as well as white glass was extensively used; it had a greenish tint in the first days of the empire, but had sensibly improved in color and quality in the days of Constantine. The first production of a white glass like crystal was in the days of Nero. Its use was most extensive, and it was either blown or stamped aecebrding to the objects required. Glass vases, vases vitrea escaria potoria, are mentioned. Su are costly cups of many colors, purple ones of Lesbos, and balsamarii, especially the kind long called lachrymatories, which held perfumes, medicine, drugs, and other substances like modern vials, amphora?, ampulla, pillar-molded bowls, bottles for wine (laden). urns (urna) for holding the ashes of the dead, and pillar-molded bowls or cups (pocula).
Besides these articles of amusement and luxury, hair-pins, beads, rings, balls, draughtsmen, dice, knuckle-bones (astraguli), mirrors, multiplying•glasses, prisms, magnifying-glasses, telescopes, and water-clocks were made of this material.
Many vases are stamped, and some, principally of square shape, have the initials and devices of their makers or contents, as eye-waters, impressed on the bottom. Most of the precious stones were successfully imitated in glass pastes; and the empress Salonina was egregiously cheated by a fraudulent jeweler. But the most remarkable works in glass are the camel vases (toreumata vitri); of which the most celebrated is the Portland vase in the British museum, a two-handled vessel about 10 in. high, of transparent dark blue glass, coated with a layer of opaque white glass, which has been treated as a cameo, the white coating having been cut down, so as to give on each side groups of figures delicately executed in relief. The subject is the marriage of Peleus and Thetis, and the urn held the ashes of a member of the imperial family of Severus Alexander, who died 221-35 A.D. This emperor had imposed a tax upon glass. It was found in a magnifi
cent sarcophagus in the Monte del Grano, near Rome. A vase of smaller size, but of similar fabric, with arabesques, found at Pompeii, exists in the Naples museum; and numerous fragments of even finer vases, some with five colors, exist in different museums. In the reign of Tiberius, an adventurer pretended that he had invented flexible glass, and threw down a vase which only bent, and which he readjusted with a hammer; he seems to have connected it iu some way with the philosopher's stone, and the emperor is said to have banished him or put him to death. This invention is said to have been twice reinvented in modern times—once by an Italian at the court of Casimir, king of Poland. In the 3d c. A.D. appeared the diatreta or "bored vases," consisting of cups ( pouela) having externally letters, and net-work almost detached from the glass, but connected by supports; all which must have been hollowed out by a tool, involving great labor. One vase of this class, bearing the name of 1.4faximianns, who reigned 236-310 A.D., fixes their age. At a later period, bowls of engraved glass, having 'subjects of gladiatorial fights, came into use. Still later, apparently in the 5th c., a new style of glass ornamentation was introduced, consisting of the figures of Christ and legends of saints, and the portraits of private persons laid on in gold upon one layer of over which was placed another, through which they appeared. At the close of the Byzantine empire, the glass art was still rich and ornamental. Achilles Tatius describes a vase which, when filled with wine, made the portion representing the bunches of grapes seem red, as if ripened by the autumn. The numerous beads called serpents' eggs or adder stones (girth/ nerdryr), found throughout Roman Britain, were imported by route of Gaul to Britain, or made in Britain. Glass was cheap under the empire, and Strabo informs us that in his days in Rome a glass cup and saucer only cost an as (about a half-penny). Such articles, indeed, can only have been of the commonest kind, as Nero is said to have paid 6,000 sesterees, or about £50,000, for two- cups of moderate dimensions. Aurelian made the Alexandrines pay a tax of glass. A peculiar white glass seems to have been made at Carthage under the Roman empire. Glass gems for rings (came gamma) were in most extensive use. Glass, however, was considered always something costly and rare, and is mentioned as such in the R.evelations and in the Recognitions of ,St. Clement, in which St. Peter is described as praying to see some mar velous columns of this material in the island of Aradus. At the close of the Roman empire, only two kinds of glass appear to have been manufactured—bottles of a greenish glass in the west, and the kyalina diachrysa, or gilded glass of many colors, in the east.