Glass resists the action of all acids except the "fluoric." It loses nothing in weight by use or age. It is more capable than all other substances of receiving the highest degree of polish. If melted seven times over and properly cooled in the furnace, it will receive a polish rivalling almost the diamond in brilliancy. It is capable of receiving the richest colors procured from gold or other metallic coloring, and will retain its original brilliancy of hue for ages. Medals, too, embedded in glass, can be made to retain forever their original purity and appearance. Another singular property of glass is shown in the fact, that when the furnace, as the workmen term it, is settled, the metal is perfectly plain and clear; but if by accident the metal becomes too cool to work, and the furnace heat required to be raised, the glass, which had before remained in the open pots perfectly calm and plain, immediately becomes agitated or boiling. The glass rises in a mass of spongy matter and bubbles, and is rendered worthless. A change is however immediately effected by throwing a tumbler of water upon the metal, when the agitation immediately ceases, and the glass assumes its original quiet and clearness. All writers upon the subject of glass manufacture fail to show anything decisive upon the precise period of its invention. Some suppose it to have been invented before the flood. Nervi traces its antiquity to the yet problematical time of Job. It seems clear, however, that the art was known to the Egyptians thirty-five hundred years since; for records handed down to us in the form of paintings, hieroglyphics, &c., demonstrate its existence in the reign of the first Osirtasen, and existing relics in glass, taken from the ruins of Thebes, with hieroglyphical data, clearly place its antiquity at a point fifteen centuries prior to the time of Christ. Mr. Kennett Loftus, the first European who has visited the ancient ruins of Warka, in Mesopotamia, writes thus: "Warka is no doubt the Erech of Scripture, the second city of Nimrod, and it is the Orchoe of the Chaldees. The mounds within the walls afford subjects of high interest to the historian; they are filled, or I may say composed, of coffins piled upon each other to the height of forty-five feet." "The coffins are of baked clay, covered with green glaze, and embossed with the figures of warriors, &c., and within are ornaments of gold, silver, iron, copper, and _glass_."