The hair : its growth, care, diseases, and treatment / by C. Henri Leonard.

  • Leonard, C. Henri (Charles Henri), 1850-1925.
Date:
1880
Catalogue details

Licence: Public Domain Mark

Credit: The hair : its growth, care, diseases, and treatment / by C. Henri Leonard. Source: Wellcome Collection.

    16/328 (page 12)
    CHEMISTRY OF THE HAIR. between the chemical analyses of the different substances given than there is between the two different analyses of the hair itself. This variation is in part due to the fact that no two heads of hair are exactly alike in their chemical composition; they vary much with the color of the hair too. Thus, for intsance: Brown hair gives us the largest proportion of carbon, while sulphur, oxygen and hydrogen are found in a smaller ratio. In black hair we find a larger amount, comparatively, of oxy- gen and sulphur, but a smaller amount of carbon and hydrogen. Fair hair is the richest in oxygen and sulphur, but has less carbon and hydrogen than hair of any other color. In red hair is found a reddish oil, a small quantity of iron, but a large quantity of sulphur. White hair, besides the sulphate of alumina, yields the phos- phate of magnesia, a whitish oil, and, in the aged, a large amount of the phosphate of lime. The beard gives us more carbon and hydrogen than the head hair, but less oxygen and sulphur; the quantity of nitrogen is, however, about the same. Upon the variation of the amount of these different chemical constituents present in hair of a given color, de]3end the dif- ferent shades of color caused by the use of the same dye, as spoken of in the chapter devoted to the consideration of hair- dyes and bleaching agents. The peculiar offensive odor noticed on burning hair is due to the decomposition of its nitrogenous or animal substance, called keratin, thus setting the previously combined sulphur free. This substance, which goes to make up the bulk of the hair, is soluble in alkalies, with the formation of ammonia, and strong sulphuric acid; but insoluble in boiling acetic acid, which dissolves the nails, horn and epidermis, and hence distinguishes