The city of Paris, like our own national capitol, contains a large number of literary charlatans, whose existence depends upon the marvelous stories they are able to erve up for the journals for which they correlpond, and hence these Bohemians of the press do not hesitate to manufacture the most improbable canards, to give spice to their correspondence, and gratify the prevalent appetite for the extraordinary. Royalty appears to receive the special attention of these gentlemlh, and the most trifling event of interest pertaining to the courts of Europe is embellished and magnified through their exuberant fancies in such a degree as to make it extremely palatable to those for whom they cater. In detailing the many discoveries and inventions in science and the mechanic arts for which the French people are noted, they often mar and render them ridiculous to those of their readers whose education enables them to detect the proclivities of their trade ; but it is seldom that one of these correspondents entrenches so far upon acknowledged principles in science as to manufacture and start a story involving a scientific solution. One, however, has had the temerity to do so in the following :— TROUBLE IN A JEWEL CASKET.— An alarm of a most serious nature was spread throughout the Tuileries on Monday. The Empress having expressed her intention of wearing the beautiful parure of pearls at the ball given in honor of the Queen of Holland, it was discovered on opening the ecrin which contains the necklace, that two of the precious gems were discolored, and sickening of that disease, the terror of jewelers and guardians of crown jewels, the cure for, or preventive of which have yet to be discovered. By this disease the pearls change color, then become scaly, and finally crumble to powder. The malady is contagious ; and if the first pearl attacked be not removed, every one confined in the same ecrin will soon be lost. In the present case, the separation of four of the diseased pearls from the necklace was speedily resolved upon by Kramer, the court jeweler, as the only means of saving the rest.—Paris letter. We need hardly inform our readers that the above statement, beyond the assertion of discoloration, although studiously clothed in the positive language and precision of truth, cannot, from the nature of pearls, have any foundation whatever in fact. The exact formation of pearls has given occasion to any number of theories, including the poetical hypothesis of Pliny, that they are the result of the dew of heaven, imbibed by the shell oyster, which, like a liquid pearl, insinuates itself into the body of the same, fixes by its salts, and there assumes the color, hardness, and form of pearl ; and many others of an equally absurd and extravagant character Sufficient, however, is known of pearls to know that they are calcareous, and are all liable to change with wearing, and that in many cases they become of little value in a hundred years, especially the white ones, which often turn yellow and spoil in fifty years' time. Pliny tells us that Cleopatra was able to gain a wager from her lover, by dissolving her pearls in vinegar; but it is clear that she must have employed stronger vinegar than that at present used, as the hardness and natural enamel of a sound pearl cannot be easily dissolved by a weak acid. The pearls of the Empress may, therefore, have become discolored from age, or the action of an acid, or like cause ; but the story that this was occasioned by a contagious disease as asserted, is evidently the result of intellectual friction, in Qonnection with a well-known fact, in the inventive brain of some Paris correspondent, domiciled in the street of the Four Winds of the Quartier Latin. An engraving and description of Hock's gas apparatus is unavoidably postponed.