Red Color From Picric Acid.

Harper's new monthly magazine, 41 / 1870

According to the Chemical News, picric acid may be employed for imparting a beautiful red color to ivory, bone, and horn, by means of the following method: Take 4 grammes of the picrid acid (the gramme about equal to 15 grains), and dissolve in 250 grammes of boiling water; and, after cooling, add 8 grammes of liquid ammonia. Dissolve also two grammes of crystallized fuchsine (magenta) in 45 grammes of alcohol, dilute with 375 grammes of hot water, and next add 50 grammes of ammonia. As soon as the red color of the magenta solution has disappeared the two solutions are mixed together, making a bulk of liquid amounting to about a pint, which is a sufficient quantity for dyeing from four to six sheep-skins. Ivory and bone should be placed in very weak nitric or hydrochloric acid first, before being immersed in the ammoniacal liquid; wood can not be dyed by this liquid unless it has been previously painted over with paste made from flour. When, to the ammoniacal liquid, some gelatine solution is added, it will serve as a red ink, which does not attack steel pens. By changing the proportions of the magenta and picric acid, the tints obtained may be varied from a bluish-red to a bright orange-red. The desired colors do not appear until the ammonia is evaporated.

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