Ichthyol and resorcin as representatives of the group of reducing remedies / by P.G. Unna.

  • Unna, Paul Gerson, 1850-1929.
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: Ichthyol and resorcin as representatives of the group of reducing remedies / by P.G. Unna. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    a deep blackening; the same occurs with the milder remedies, as resorcin. These examples can be multiplied ad infinitum. Notwithstanding, I believe that yet other factors, known and unknown, play a part in the process; for example, the thickness and the quantity of moisture of the horny layer, its transparency, etc. It is, for example, striking that, in general, the horny layer of the palms always undergoes a more rapid and more intense blackening than that of other parts of the body, a fact which cannot be well explained through the reaction of the secretion of the skin alone, but is rather explained through its strict analogy to the especially rich blackening which silver salts produce upon the horny layer of the palm of the hand, which indicates that, with each deeper coloration, processes of reduction also play a role, as they become extended through the thicker horny layer. These artificial colors have, therefore, without a doubt, a relation to certain physiological and patho- logical colors of the horny layer, which I have shown, in the place just cited, to be a result of a more or less decided collec- tion of a pigment peculiar to the horny substance ; that is, the “ horny substance color.” Here belongs the color of the hair, varying from light yellow to an ebony black, depending upon whether this pigment is diffusely spread out in the hair-cells or not. Likewise the diffuse color, and the brown granular accu- mulations found between the horny cells of the comedo heads {Virchow's Arch., Bd. 82, p. 175), concerning which I have elsewhere shown that they are not dirt, for which, I am sorry to say, they still pass in most text-books, though certainly with- out proof. In a certain article (“ Uber das Pigment der Menschlichen Haut”) I have produced evidence that the matter in question, in reference to this horny layer, is a reduction product provided by the horny substance itself, which in minute subdivisions is colored yellow, but in larger masses is brown, or even black, and is oxidized by peroxide of hydrogen, with fading of the dark color. I therefore assume, as a logical consequence of this conception, that this reduced body, the horn color, appears under the influence of the reducing agent in a greater or less quantity; and even if it does not influence the shade, still it