Trade Wrinkles.

Shellac Cement for Rubber.—Powdered shellac is softened in ten times its weight of water of ammonia, whereby a transparent mass is obtained, which, after keeping some little time, becomes fluid without the use of hot water. In three or four weeks the mixture is perfectly liquid, and when applied it will be found to soften the rubber. As soon as the ammonia evaporates the rubber hardens again—it is said quite firmly—and thus becomes impervious to both gases and liquids. For cementing sheet rubber or rubber material in any shape to metal, glass, and other smooth surfaces, the cement is highly recommended.

Working of Blue and Green.—If you want to get the best results with blue ink, especially ultramarine, as well as the more brilliant greens, don't use hard rollers. Use good fresh glue-and-molasses rollers, and do not carry too much color. It is common to notice a mottled or speckled appearance in solid blue surfaces. In other cases a stringy appearance is seen. This indicates either too much moisture or too much oil in the rollers—a simple matter, but one to be watched with care. Attention to these remarks will remedy the mottled and streaky appearance of the various tints on the array of music titles often seen in the windows of our prominent music stores.

To Split a Piece of Paper.—In interleaving books, making scrap-books, and the like, it is often desirable to separate an engraving from printed matter on its back, or separate two pictures printed back to back. There are two ways to do this, says the Manufacturers' Gazette. 1. Lay the paper to be split upon a piece of glass, soak the paper thoroughly and press it smooth. Then with a little care the upper half of the sheet can be peeled off. leaving the engraving on the glass. Let this part dry, and it will come off the glass readily. 2. A better plan is to paste a piece of cloth or strong paper to each side of the sheet to be split. When dry, pull the two pieces of cloth apart suddenly and violently. Soften the paste with water, and the two halves of the sheet will easily part from the cloths. It is well to experiment with printed sheets of no value until the trick is mastered.

Substitute for Gum Arabic.—A substitute for gum arabic, which has been patented in Germany, and is likely to be largely used for technical purposes now that good gum arabic is so scarce, is made as follows, according to the American Druggist: Twenty parts of powdered sugar are boiled with seven parts of fresh milk, and this is then mixed with fifty parts of a 36% solution of silicate of sodium, the mixture being then cooled to 122° F, and poured into tin boxes, where granular masses will gradually separate out, which look very much like pieces of gum arabic. This artificial gum copiously and instantly reduces Fehling's solution, so that, if mixed with powdered gum arabic as an adulterant, its presence could be easily detected. The presence of silicate of sodium in the ash would also confirm the presence of adulteration.

Glue Stamps.—Herr Anton Gerhard, of Emden, writes to the Nurnberg Stereotypeur: « I have ceased using rubber stamps in my business, and now use glue stamps, for which for stamping purposes I use letterpress ink. The glue stamp I make in the following manner:—Upon the composition I place several leaves of tin-foil; over this a piece of felt is placed and the whole pressed tightly. I loosen the press at once and take out the tin-foil matrix, which is now ready for use. Oil the matrix slightly and surround with oiled bridges or reglets; then pour fluid glue mixed with a trifle of roller composition over it. After the same gets cool the layer of glue will loosen itself slightly from the matrix and become sufficiently hard, but still remains elastic. The glue I use is pure carpenters' glue. During the first few days the glue may appear somewhat soft, but it soon becomes nice and hard, and retains sufficient elasticity. I am very well satisfied with the stamp, as it prints in an excellent manner. »