Powder the ink and the gum, and triturate small quantities of the powder with rose water until a uniform black liquid results, which must be free from granules. This liquid is placed in a bottle and the rest of the rose water added. Kohol can be used only by persons with black hair, and is employed particularly for dyeing the eyebrows. As the coloring matter of this preparation consists of carbon in a state of fine division, the dye is perfectly harmless. VEGETABLE DYE. Silver nitrate 2 oz. Distilled water 1 qt. This hair dye produces a deep black color, but cannot be recommended, as it is injurious to the hair. Its full effects appear only after the lapse of some hours. POTASSIUM PERMANGANATE. Potassium permanganate 5½ oz. Distilled water 2 qts. Crystalline potassium permanganate is soluble in water, forming a dark violet solution. When brought in contact with an organic substance—paper, linen, skin, horn, hair—it is rapidly decolored and imparts to the substances named a brown tint due to hydrated oxide of manganese. The hair is washed, as stated above, to remove the fat, and the dilute solution applied with a soft brush; the color is produced at once and according to the degree of dilution this innocuous preparation can be made to give any desired color from blond to very dark brown. Of course, this preparation can be used for the beard as well as the hair. All the hair dyes here and elsewhere given stain the skin as well wherever they come in contact with it; hence care should be taken to protect the skin during their application. B. Double Hair Dyes. SILVER HAIR DYES. This and similar hair dyes consist of two preparations, preserved in bottles I. and II.; the latter, containing the silver solution, should be of dark amber-colored or black glass, as the silver salts are decomposed by light. It is utterly useless to employ blue glass for this purpose, as this admits the chemical rays of light as easily as flint glass. For use, some of the liquid from bottle I. is poured into a cup and the hair is moistened with it by means of a soft brush. The liquid from bottle II. is poured into a second cup and applied with another brush. BROWN DYE. I. (_In White Bottle._) Sulphide of potassium 7 oz. Alcohol 1 qt. II. (_In Dark Bottle._) Silver nitrate 4¼ oz. Distilled water 1 qt. BLACK DYE. I. (_In White Bottle._) Sulphide of potassium ½ lb. Alcohol 1 qt. II. (_In Dark Bottle._) Silver nitrate 5½ oz. Distilled water 1 qt.