ON THE NATURE AND PROPERTIES OF GLASS, AND THE HISTORY OF ITS MANUFACTURE. NATURE OF GLASS. ITS VARIOUS PROPERTIES. ITS UTILITY. — THE ASSISTANCE IT LENDS TO SCIENCE. EXCESSIVE PRICES FORMERLY PAID. ORIGIN OF ITS ENGLISH NAME.ARISTOTLE'S PROBLEMS. FIRST INVENTION ASCRIBED TO THE PHOENICIANS. MANUFACTORIES OF ALEXANDRIA. UTENSILS FOUND IN HERCULANEUM. MALLEABLE GLASS. TAX ON GLASS BY ALEXANDER SEVERUS. PORTLAND VASE. GLASS EMPLOYED IN FORMING WINDOWS. - PRIVILEGES GRANTED TO MANUFACTURERS IN FRANCE. PLATE-GLASS CASTING. ESTABLISHMENT AT ST. GOBAIN. ITS EARLY FAILURE, AND REVIVAL. - MANUFACTURE COMMENCED IN ENGLAND. OF FLINT GLASS. OF PLATE GLASS. CHINESE UNACQUAINTED WITH GLASS MAKING. IMPORTANCE OF THE MANUFACTURE IN ENGLAND. - GLASS MADE A SOURCE OF REVENUE. MANY circumstances contribute to render glass one of the most curious and interesting of manufactured substances. Although perfectly transparent itself, not one of the materials of which it is made partakes of that quality. Exceedingly brittle while cold, it becomes, by the application of heat, so remarkably flexible and tenacious as to be convertible into every form that fancy may dictate or convenience suggest. Its great ductility is shown in a very striking manner by the slender filaments — small as the fibres of a spider's web into which it is spun for ornamental purposes. Many hundred feet of these filaments may be drawn out from a heated mass in the space of one minute. Its pliancy and elasticity are proved by the facility with which, when in the state just mentioned, it may be bent and retained in various forms, and by the energy wherewith its original shape is resumed at the moment of release from its constrained position. The impermeability of glass to water, even under a considerable degree of pressure, is well ascertained. A few years ago, the reverend Mr. Campbell, while on a voyage to Southern Africa, among other philosophical experiments wherewith he amused himself, caused two globular glass bottles hermetically sealed to be lowered by means of leaden weights to the depth of 1200 feet beneath the surface of the sea. These, through the united and continuous exertions of ten men during fifteen minutes, were again drawn up, and were found to be perfectly empty. The continued exposure of glass to the greatest heat whereby it is melted, does not produce any sensible diminution in its weight and quantity, or any alteration of its properties. It is capable of receiving colours, and of retaining them in all their lustre for an indefinite period. The strongest acids with one exception that will be noticed-have no effect upon it; a circumstance that renders glass additionally useful in assisting the researches of chemists. It is capable of receiving the most perfect polish, preserves all its beauty, and does not lose the smallest portion of its substance by the longest and most frequent use. The admirable qualities and important uses of glass have been so happily pointed out by one of the most celebrated writers of the last century, that no apology will be needed for the insertion of the passage. Who, when he saw the first sand or ashes by a |