_Pyrogallic acid_ may be used for darkening the hair, not only in combination with metallic substances, but also by itself, or with alkalies. Hair moistened with pyrogallic acid becomes under the influence of light and air dark gray to blackish. However, the color is not handsome, and appears only in the course of weeks. In connection with alkalies, pyrogallic acid produces a red-brown to black-brown coloration. Under the name of _Kohol_, an extremely fine powder, consisting of black sulphide of antimony, is used in Egypt by all classes for blackening the edges of the eyelids and the eyebrows. A hair dye, much used in the Orient, is _henna_, the dried and pulverized leaves of _Lawsonia inermis_. By the women this powder is used for coloring the hair and nails red-brown. In the Turkish sweating baths the attendants scatter the henna upon the hair of the women and tie it upon the finger nails. The women then frequently remain for hours in the steam bath, whereby the powdered henna is converted into an extract-like mass which colors hair and nails red-brown. It is said that henna even colors the coal-black hair of the Arabs red-brown, which is considered beautiful. Before treating with henna, the hair must be freed from fat with soap or fuller's earth. Hair dyed red with henna acquires a beautiful black color when subsequently treated with indigo, this mode of dyeing black being much in vogue in the Orient. The process is as follows: The hair, being freed from fat with soap, is divided into separate strands and anointed with quite a stiff paste prepared from pulverized henna and lukewarm water. The hair, after being smoothed, is allowed to remain for at least one hour in contact with the paste, and is then rinsed off with lukewarm water. Being slightly dried, it is then in the same manner anointed with a paste prepared from indigo and water, and allowed to remain in contact with it for one hour. The hairs which were colored orange-red by the henna, now have a greenish-black appearance, but by the oxidation of the indigo in a short time acquire an intensely blue-black color, which is extraordinarily durable, the hair only after several months requiring to be again dyed. The freshly expressed juice and the fresh parenchyma of _green walnut shells_, or of unripe walnuts, gradually color light or gray hair dark to nut-brown. The coloring substance is not thoroughly known, but is very likely a phloroglucide; it is extracted by fats and alcohol, but, according to Paschkis, is no longer effective in such solution. This, however, is not correct in regard to the alcoholic extract, because the extract from ordinary walnut shells, prepared by mixing the expressed juice of green walnut shells with 10 parts of alcohol, allowing the mixture to stand for ten days, and then filtering, also colors brown.