_Gum for Backing Labels._—Take any quantity of clear, pure dextrine and mix it with boiling water until it assumes the consistency of ordinary mucilage. Apply thinly with a full-bodied, evenly made, and wide camel’s-hair brush. The paper should not be too thin or unsized. The preparation will dry quickly, and adhere when slightly wet. NOTE.—No more of the dextrine should be mixed at one time than can be used at once, as it cannot be remelted easily. * * * * * _Mucilage for Postage Stamps, Envelopes, etc._, is composed of dextrine 2 parts, acetic acid 1 part, alcohol 1 part, water 5 parts. * * * * * _Common Prepared Glue._—Dissolve 2 lbs. good common glue in 3 pints warm water, and add 1 quart of strong vinegar. Ready to use after twenty-four hours. * * * * * _For making Magenta Surface Paper._—1½ oz. of Magenta, (aniline,) ½ oz. Bismarck brown, (aniline,) 1 cake of glue; put these into 4 gallons of boiling water. Coat the paper with this, using an 8-inch double-filled camel’s-hair brush. Quantity given will coat two reams of double-crown. A hard-sized paper must be used. * * * * * _Coloured Writing Inks._—The following receipts have been well tested, and are commended by good authorities as preferable to the solutions of aniline dyes, which are now so extensively used as coloured inks:— GREEN.—Two parts acetate of copper, one part carbonate of potash, and eight parts of water. Boil until half evaporated, and filter. BLUE.—Three parts Prussian blue, one part oxalic acid, and thirty parts of water. When dissolved, add one part of gum-arabic. YELLOW.—One part fine orpiment, well rubbed up with four parts thick gum water. RED.—With the aid of a gentle heat, dissolve four grains of carmine in 1 oz. of aqua ammoniæ, and add 6 grains of gum-arabic. GOLD.—Rub gold leaf, such as is used by bookbinders, with honey, till it forms a uniform mixture. When the honey has been washed out with water, the gold powder will settle at the bottom, and must be mixed with gum water in sufficient quantity. SILVER.—Silver leaf treated in precisely the same manner gives a silver ink. Both these inks may be polished with ivory when dry. BLACK.—Three ounces crushed gall-nuts, two ounces crystallized sulphate of iron, two ounces gum-arabic, and twenty-four ounces water. WHITE.—Fine French zinc-white, or white lead, rubbed up with gum water to the proper consistency. * * * * *