Violet ink is obtained by dissolving one part of aniline violet-blue in 300 parts of water. This ink is quite limpid, dries quickly, and gives a remarkably dark color. It is necessary that new pens should be employed in using it, as the smallest quantity of ordinary ink mixed with it causes its alteration. Blue ink is made by dissolving 1 part of soluble Paris-blue in 250 parts of boiling water; red ink, by dissolving 1 part of soluble fuchsin in 200 parts boiling water. While ordinary inks are decomposed by numerous substances, and notably by hydrochloric acid, aniline inks are completely ineffaceable from the paper on which they are used. They resist the action of acids, and even of chlorine.