Part 323

Potassium ferricyanide 2.5 parts Distilled water 10.0 parts

allow the mixture to stand in the dark half an hour. Apply the preparation on the paper by means of a soft brush, in artificial light, and dry in the dark. Next, expose the paper to light until it appears dark violet, place in water for 10 seconds, air a short time, wash with water, and finally dip in a solution of

Eau de javelle 50 parts Distilled water 1,000 parts

until it turns dark blue.

«Filter Paper.»—This process consists in dipping the paper in nitric acid of 1.433 specific gravity, subsequently washing it well and drying it. The paper thereby acquires advantageous qualities. It shrinks a little and loses in weight, while on burning only a small quantity of ash remains. It possesses no traces of nitrogen and does not in any way attack the liquid to be filtered. Withal, this paper remains perfectly pervious for the most varying liquids, and its filtering capacity is in no wise impaired. It is difficult to tear, and still elastic and flexible like linen. It clings completely to the funnel. In general it may be said that the strength of the filtering paper thus treated increases 100 per cent.

«Fireproof Papers.»—I.—Ammonium sulphate, 8 parts, by weight; boracic acid, 3 parts; borax, 2 parts; water, 100 parts. The temperature should be about 122° F.

II.—For paper, either printed or unprinted, bills of exchange, deeds, books, etc., the following solution is recommended: Ammonium sulphate, 8 parts; boracic acid, 3 parts; sodium borate, 1.7 parts; water, 10,000 parts. The solution is heated to 122° F., and may be used when the paper is manufactured. As soon as the paper leaves the machine it is passed through this solution, then rolled over a warm cylinder and dried. If printed or in sheets, it is simply immersed in the solution, at a temperature of 122° F., and spread out to dry, finally pressed to restore the luster.

«Hydrographic Paper.»—This is paper which may be written on with simple water or with some colorless liquid having the appearance of water.

I.—A mixture of nut galls, 4 parts, and calcined sulphate of iron, 1 part (both perfectly dry and reduced to very fine powder), is rubbed over the surface of the paper, and is then forced into its pores by powerful pressure, after which the loose portion is brushed off. The writing shows black when a pen dipped in water is used.

II.—A mixture of persulphate of iron and ferrocyanide of potassium may be employed as in formula I. This writes blue.

«Iridescent Paper.»—Sal ammoniac and sulphate of indigo, of each 1 part; sulphate of iron, 5 parts; nut galls, 8 parts; gum arabic, 1⁠/⁠8 part. Boil them in water, and expose the paper washed with the liquid to (the fumes of) ammonia. {505}

«Lithographic Paper.»—I.—Starch, 6 ounces; gum arabic, 2 ounces; alum, 1 ounce. Make a strong solution of each separately, in hot water, mix, strain through gauze, and apply it while still warm to one side of leaves of paper, with a clean painting brush or sponge; a second and a third coat must be given as the preceding one becomes dry. The paper must be, lastly, pressed, to make it smooth.

II.—Give the paper 3 coats of thin size, 1 coat of good white starch, and 1 coat of a solution of gamboge in water, the whole to be applied cold, with a sponge, and each coat to be allowed to dry before the other is applied. The solutions should be freshly made.

Lithographic paper is written on with lithographic ink. The writing is transferred simply by moistening the back of the paper, placing it evenly on the stone, and then applying pressure. A reversed copy is obtained, which, when printed from, yields corrected copies resembling the original writing or drawing. In this way the necessity of executing the writing or drawing in a reversed direction is obviated.

«MARBLING PAPER FOR BOOKS.»

Provide a wooden trough 2 inches deep and the length and width of any desired sheet; boil in a brass or copper pan a quantity of linseed and water until a thick mucilage is formed; strain it into a trough, and let cool; then grind on a marble slab any of the following colors in small beer:

For Blue.—Prussian blue or indigo.

Red.—Rose pink, vermilion, or drop lake.

Yellow.—King’s yellow, yellow ocher, etc.

White.—Flake white.

Black.—Burnt ivory or lampblack.

Brown.—Umber, burnt; terra di sienna, burnt.

Black mixed with yellow or red also makes brown.

Green.—Blue and yellow mixed.

Orange.—Red and yellow mixed.

Purple.—Red and blue mixed.

For each color have two cups, one for the color after grinding, the other to mix it with ox gall, which must be used to thin the colors at discretion. If too much gall is used, the colors will spread. When they keep their place on the surface of the trough, when moved with a quill, they are fit for use. All things in readiness, the colors are successively sprinkled on the surface of the mucilage in the trough with a brush, and are waved or drawn about with a quill or a stick, according to taste. When the design is just formed, the book, tied tightly between cutting boards of the same size, is lightly pressed with its edge on the surface of the liquid pattern, and then withdrawn and dried. The covers may be marbled in the same way, only letting the liquid colors run over them. In marbling paper the sides of the paper are gently applied to the colors in the trough. The film of color in the trough may be as thin as possible, and if any remains after the marbling it may be taken off by applying paper to it before you prepare for marbling again. To diversify the effects, colors are often mixed with a little sweet oil before sprinkling them on, by which means a light halo or circle appears around each spot.

«WATERPROOF PAPERS.»