The composition of which printing-rollers are made was discovered by a Salopian printer. Not being able to find the pelt-ball, he inked the type with a piece of soft glue which had fallen out of a glue pot. It was such an excellent substitute that, after mixing molasses with the glue, to give the mass proper consistency, the old pelt-ball was entirely discarded. _Mezzotinting._ This art was suggested by the simple accident of the gun-barrel of a sentry becoming rusted with dew. _Whitening Sugar._ The process of whitening sugar was discovered in a curious way. A hen that had gone through a clay puddle went with her muddy feet into a sugar house, leaving her tracks on a pile of sugar. It was noticed that wherever her tracks were the sugar was whitened. Experiments were instituted, and the result was that wet clay came to be used in refining sugar. _Discovery of Glass._ Pliny informs us that the art of making glass was accidentally discovered by some merchants who were traveling with nitre, and stopped near a river issuing from Mount Carmel. Not readily finding stones to rest their kettles on, they employed some pieces of their nitre for that purpose. The nitre, gradually dissolving by the heat of the fire, mixed with the sand, and a transparent matter flowed, which was, in fact, glass. _Essence of Pearl._ A French bead-maker named Jaquin discovered the manner of preparing the glass pearls used at present, which approach as near to nature as possible, without being too expensive. He once noticed, at his estate near Passy, that when the small fish called _ables_ or _ablettes_ were washed, the water was filled with fine silver-colored particles. He suffered the water to stand for some time, and obtained from it a sediment which had the lustre of the most beautiful pearls, which suggested to him the idea of making pearls from it. He scraped off the scales of the fish, and called the soft shining powder which was diffused in the water essence of pearl, or _essence d'orient_. He succeeded in coating the interior of glass beads with the pearly liquid, and amassed a large fortune. This was during the reign of Henry IV. (according to some authors), and Jaquin's heirs continued the business down to a late period, and had a considerable manufactory at Rue de Petit Lion, at Paris. It required from eighteen to twenty thousand fish (which were not more than four inches in length) to make a pound of the essence of pearl. These pearls were frequently taken for genuine ones. Mercure Galant (1686), tells us in that year of a poor marquis, who, being in love with a lady, gained her affections by presenting her with a string of artificial pearls. They cost him not more than three louis, while she, believing them to be genuine pearls, valued them at 2,000 francs. Jewelers and pawnbrokers were frequently deceived by them. _Diminutive Note Paper._