To detect ground Wood in Paper.—Mix three parts of strong nitric acid with one part of sulphuric acid: a drop of this solution will immediately turn paper containing an admixture of ground wood a brown colour.
French Gold Printing.—French copal varnish 1 oz., mastic varnish ¼ of an oz.; mix together and add twenty drops to the black ink table, and distribute; take an impression and apply, with wool, gold leaf, Dutch metal, or bronze. Apply the bronze with cotton wool and rub hard over the black ink. After each fifty printed, wipe off the superfluous gold from the type with a silk handkerchief.
Transfer Varnish.—Take equal quantities of fir balsam and spirits turpentine. Mix, shake well, and set in a warm place until clear. Used in decalcomania, and for maps, prints, drawings, and other articles of paper; and also to prepare tracing papers, and to transfer engravings.
To make Paper Waterproof.—Dissolve 8 oz. of alum and 3⅓ oz. of white soap in 4 pints of water. In another vessel dissolve 2 oz. of gum-arabic and 4 oz. of glue in 4 pints of water. Mix the two solutions and heat them over the fire. Then immerse the paper, sheet by sheet, in the hot liquid, then hang them up edgewise to dry, or pass them between heated cylinders.