go forth to the world it would lower the value of the precious metals.[10] The secret, consequently, perished. A chance, however, arose for its recovery during the reign of Louis XIII., a period that might be considered more favorable to such undertakings; but unfortunately with no better result. The inventor on this occasion submitted a bust formed of malleable glass to Cardinal Richelieu, who, instead of rewarding him for his ingenuity, sentenced him to perpetual imprisonment, on the plea that the invention interfered with the vested interests of the French glass manufacturers.[11] We should have more reliance on these anecdotes of the martyrs of glass, if they had bequeathed to mankind some clew to the secret that is supposed to have gone to the grave with them. To die for a truth, and at the same time to conceal it, is not the usual course of heroic enthusiasts. [Footnote 10: This story is attested, with slight variations, by several writers, Petronius, Dion Cassius, Pliny, and Isidorus. Pliny says that the populace, imagining that their interests would be injured by the discovery, destroyed the workhouse, tools, and dwelling of the artificer.] [Footnote 11: Blancourt.] Many attempts have been made to produce a material resembling glass that should possess the quality of malleability, and respectable evidence is not wanting of authorities who believed in its possibility, and who are said to have gone very near to its accomplishment. An Arabian writer[12] tells us that malleable glass was known to the Egyptians; but we must come closer to our own times for more explicit and satisfactory testimony. Descartes thought it was possible to impart malleability to glass, and Boyle is reported to have held the same opinion. But these are only speculative notions, of no further value than to justify the prosecution of experiments. Borrichius, a Danish physician of the seventeenth century, details an experiment by which he obtained a malleable salt, which led him to conclude that as glass is for the most part only a mixture of salt and sand, he saw no reason why it should not be rendered pliant. The defect of his logic is obvious; but, setting that aside, the fallacy is practically demonstrated by his inability to get beyond the salt. Borrichius also thought that the Roman who made the vase for Tiberius, may have successfully used antimony as his principal ingredient. Such suppositions, however, are idle in an experimental science which furnishes you at once with the means of putting their truth or falsehood to the test. There is a substance known to modern chemistry, _luna cornea_, a solution of silver, which resembles horn or glass, is transparent, easily put into fusion, and is capable of bearing the hammer. Kunkel thought it was possible to produce a composition with a glassy exterior that should possess the ductile quality; but neither of these help us toward an answer to Aristotle's question. Upon a review