The custom of dyeing the hair is universal in the Orient; in the Occident, however, hair dyes are also frequently used, namely, to hide the grayness of the hair, sometimes to give the hair a preferred color. Hair dyes, which are very numerous, may be divided into groups—those containing the dye-stuff ready formed, and those in which it is produced in the hair by some chemical process. Some hair dyes contain substances which in their nature are decidedly injurious to the hair; such articles, of course, must be dispensed with because, if frequently employed, they would certainly lead to baldness. We shall return to this subject in connection with the several preparations. Regarding the use of hair dyes, especially those consisting of two separate portions, we may state that it is necessary to remove the fat from the hair before applying the dye, as the chemicals in question do not adhere well to fat. The hair should be thoroughly washed once or twice with soap, and dyed when nearly dry. When dyeing the hair the preparations should first be diluted; if the color is not deep enough, the process is repeated. If the preparation is used at once in a concentrated form, a color may result which has no resemblance to any natural tint; hair meant to be black may assume a metallic bluish-black gloss. A. Simple Hair Dyes. LEAD HAIR DYE. Oxide of lead 4 lb. Quicklime 1 lb. Calcined magnesia 1 lb. The ingredients are rubbed to a very fine powder and for use are mixed with water, applied to the hair, and left there until the desired tint—light brown to black—is obtained, from four to twelve hours, when the powder is removed by washing. The lime by its caustic effect acts destructively on the horny substance of the hair. Moreover, _all lead preparations_ without exception are _very injurious_ to the organism; hence this hair dye is to be rejected, especially as there are harmless preparations which produce the same effect. KARSI (TEINTURE ORIENTALE). Ambergris 75 grains. Nut-galls 4 lb. Iron filings 1¾ oz. Copper filings 30 grains. Musk 30 grains. This preparation, which really comes from the Orient, is made as follows: Reduce the nut-galls to a very fine powder and roast them in an iron pan under continual stirring until they have become dark brown or almost black. This powder is triturated with the metals in fine powder and the aromatics, and preserved in a moist place. For use, some of the powder is moistened in the palm of the hand and vigorously rubbed into the hair; after a few days it assumes a deep black, natural color. The roasting changes the tannin bodies contained in the galls into gallic and pyrogallic acids which form deep black combinations with the metals, and themselves are easily transformed into brownish-black substances. KOHOL (TEINTURE CHINOISE). Gum arabic 1 oz. India ink 1¾ oz. Rose water 1 qt.