These are recipes for blue inks.

(1) Place in a tumbler a teaspoonful of soluble Prussian blue pigment, and add sufficient pure water to dissolve all the blue and make it of the proper consistency for use as ink.

(2) Allow 1 oz. of powdered indigo to stand in 7oz. of oil of vitriol for forty-eight hours. Stir occasionally, and then add 8oz. of water, thus forming sulphate of indigo. A permanent blue ink is made by dissolving 3oz. or 4oz. of this sulphate in 1 gal. of water.

(3) Dissolve 3 parts of Prussian blue and 1 part of oxalic acid in 30 parts of water, and add 1 part of gum arabic.

(4) Dissolve soluble Paris blue (cornflower blue) in alcohol.

(5) Dissolve 2oz. of Chinese blue in 1 qt. of water and add loz. of oxalic acid, when the ink is at once ready for use.