It appears from ancient testimony, that there have been many successful attempts at making glass mouldable in its cold state, or of so far altering its state as to render it malleable. There is a tradition, that a clever artist, in the time of Tiberius Cæsar, made glass both elastic and malleable, for which he was rewarded by the loss of his head. A similar discovery is said to have been made in France, in the reign of Louis XIII. The inventor presented a bust, formed of malleable glass, to the Cardinal Richelieu, and was rewarded for his ingenuity by perpetual imprisonment, lest the French glass-makers should be injured. In our day, a description of glass, perhaps more remarkable, has been discovered by Mr. Fuchs, the curious properties and important applications of which it will be proper to advert to in this place. The preparation of soluble glass does not greatly differ in its early stages from that of common glass. It is a union of silica and an alkali, which has, in addition to some of the properties of common glass, the property of dissolving in boiling water. To form this compound, carbonate of potash and stone sand, are taken in the proportion of two, to three, or four parts of charcoal, and added to every ten parts of potash, and fifteen of sand. The charcoal accellerates the fushion of the glass, and separates from it all the carbonic acid, a small quantity of which would otherwise remain and be injurious. The materials must first be well mixed, then fritted and finally melted at a high heat, until a liquid and homogenous mass be obtained. This is removed by means of an iron ladle, and the glass-pot filled with fresh grit. The crude glass thus obtained is usually full of bubbles; it is as hard as common glass—it is of a blackish gray, and more or less transparent at the edges. In order to prepare it for solution in water, it must be reduced to powder by pounding. One part of this glass requires from four to five of water for its solution. The water is first boiled in an open vessel; the powdered glass is added gradually, and is continually stirred to prevent adhesion. The boiling is continued for three or four hours, until no more glass is dissolved. If the boiling be checked before the liquor has thus attained the proper degree of concentration, carbonic acid will be absorbed by the potash from the air, which will produce an injurious effect. When the solution has acquired the consistency of syrup, and a density of 1·24, it is fit for use, and will keep for any length of time.