Leather and its production / [H.R. Proctor].

  • Proctor, H. R. (Henry Richardson), 1848-1927.
Date:
1929
Catalogue details

Licence: Public Domain Mark

Credit: Leather and its production / [H.R. Proctor]. Source: Wellcome Collection.

    2/42 (page 2)
    lime and natural grease, and portions of the scarf skin and hair roots which still remain. This consists in soaking in a solution of dogs’ or pigeons’ dung; which, however unpleasant, seems to answer the purpose better than any¬ thing else as yet found out. After this the skins are again worked and stretched with the knife over the beam, and are also frequently soaked in fermenting bran and water, which has a further cleansing effect. In this stage the skins are soft, clean, and white, but would still easily putrify if left wet, and if dried would become almost like a piece of horn. They are now, however, ready for the tanning, which will change all this and make them into durable and pliable eather. This is done by soaking infusions of barks and other astringent vegetable matters which have a harsh rough taste, like that of strong tea which has stood long on the leaves. This astringency is caused by the presence of matters called tannins, which will tan skin and other animal membranes, and which are consequently useful in making leather, but very injurious to the stomach. One of the oldest and most important tanning materials is the bark of the oak tree. The acorns of an evergreen oak which grows in the Levant and in Greece also contain much tannin (quite three times as much as oak bark). They are much used for tanning thick leather for the soles of boots, and are called Valonia. The inner bark of the cork-oak is also a valuable tanning material. Among other barks may be mentioned those of the larch, of the American hemlock pine, and of the Australian mimosa or wattle. The leaves of the sumach bush from Sicily are greatly used in tanning fine and soft leathers ; and the bean-like pods of Divi-divi, and Algarobilla from South America, and the hard-dried Indian fruits called Myrabolanes are very rich in tannin. Several wmods, such as the oak and chestnut in Europe, the Quebracho in Brazil, and the areca or cutch