properties are due to the presence of metallic oxide in connexion with silex, and therefore requiring a less proportion of alkali.

Of this character of artificial crystal, the author has seen an ancient drinking-glass, of a Medicean form, on a foot of considerable substance, and nearly entire, the property of a tourist, who procured it from the neighborhood of Rome. It is remarkably heavy, and appears as if it had been shaped all over at the cutting lathe, so as to raise rings out of the exterior of the solid Glass, they were certainly not welded on in the ordinary manner while hot; and the vessel has the appearance of having been blown in an open-and-shut mould, like the modern Bohemian Glasses, and the rim afterwards cut off and polished. Although no opportunity has been afforded of taking its specific gravity, it appears much heavier than modern Flint Glass, and slightly yellow in tint. It is clear, therefore, that the ancients had not only the art of colouring Glass, and of using lead in these imitations of the precious stones, but they had (at what precise period in history is unknown) likewise the knowledge of the use of lead, and perhaps barytes, to give to white Glass density and refractive beauty. In truth, the more a manufacturer gets acquainted with ancient fragments, the more firmly he appreciated the high state of perfection to which ancient workers in Glass carried their interesting art, but of which we find few records in ancient literature.

Fig. 4. Part of an ancient handle of the specific gravity, 2500. Its green tint is indicative of the presence of iron. It is in a high state of preservation owing to the conservative tendency of the iron which forms one of the constituents. The workmanship is ingenious.