Leather

Skins of animals, in which the agglutination of the fibers after drying is prevented by some method or other. It resists putrefaction, and is supple and tough. Skins consist of four layers: the epidermis; then the malpighian layer, containing the nerves, fine blood-ve els, and perspiration glands, the hair having its roots here as well as below; the third is the corium, of fibrous structure, of which leather is made; and the inner layer, the fat bearing ti ue. The hair is removed by soaking in lime water or sweating and then scraping with knives; the fatty ti ue is also scraped off. There are three varieties of leather, tanned, tawed, and oil tawed. In the first the skins, prepared as above, are subjected to a water solution of tannic acid, for a greater or le time, in proportion to their thickne , and the gelatine in them combines with the acid, forming leather. That used for the soles of shoes is made from the hides of cattle; the tannic acid is extracted from hemlock and oak bark: it requires 5 months for its production. Leather for the uppers of shoes is made from calf-skins tanned with oak bark, requiring 8 weeks. It is blacked with lampblack and fish oil on the flesh side. Ru ia leather is made from calf or sheep skins, tanned with bark of the willow, fir, or birch; it is impregnated with oil of birch and dyed on the hair side; it requires 6 weeks. Morocco leather is made from goat or kid skins, tanned with sumac, dyed with aniline colors on the hair side, requiring 3 days. Imitation morocco is made from split calf or sheep skins. Lacquered leather is made from split ox hides, coated with a black varnish at 50° С. Danish glove leather is made from goat, kid, and lamb skins, tanned with willow bark. Tawed leather is made from thin skins, sheep or goat, cleansed as in the tanning proce , and then treated with a water solution of alum and salt, the aluminium sulphate combining with the gelatine of the skins; it requires 2 to 3 weeks; the white leather for boot linings is thus made. Glove leather is made from skins of goats or lambs, tawed with a mixture of wheat flour, yolks of eggs, alum, salt and water, and dyed on the hair side. Oil-tawed or wash leather is made from ox, deer, sheep, or calf skins, cleansed as in the other proce es, fish oil being rubbed and stamped in on the hair side, which combines with the skin. The uncombined oil is removed by a solution of pota ium hydroxide.