TANNING of leather is one of the manufactures where, with an unlimited supply of hides and flist-rate balks, gums, and extracts, the goods turned out by natives of India are not of a superior quality. Inferiority of Indian leather may be ascribed to want of skill on the part of the currier, and the use of quicklime. This is probably owing to the very low rank of the artisans, for the art of leather production is well understood and snccessfully practised by the Euro pean tanners, the leathers Made by them being scarcely inferior to that made in Europe. In the usual native process, the raw hides, on first being removed, are steeped in stone vats for four and five weeks in a strong pickle of salt and water ; from ten to fifteen hides aro placed in each vat. IVIiile steeping, a pint or quart of the milk bush, Euphorbia tirucallt, is thrown into each vat. This contains a considerable quantity of elastic gum, and is used for water-proofing leather, and render ing cords elastic. Currying the leather is the province of the wife, while manufacturing it for the i»arket belongs to the husband. The ba.sis of the skins of animals is composed of a substance to which the name of gelatine is given. One of the properties of this substance is, that when c,om bined with tannin, it forms the compound of Militate of gelatine or leather material. Tannin obtained from various SOUITCS differs materially in some of its characters. The tannin of gall nuts, which is that generally employed for chem ical purposes, is sometimes called gallo-tannic acid, to distinguish it from other species. The tannin,g materials best known in Europe are the oak bark, Peruvian bark-, and the barks of some of the acacias. The importance of oak bark has, however, been greatly diminished since the intro duction of the smnaciis, as Rhus cotiuus, the Venus smnach, and R. coriaria, the hide or elm-leaved suinach ; also of the Divi divi, or Cmsalplina coriaria ; of Valonia, the acorn cups of Quercus yEgilops ; of catechu and gambir, from the Acacia catechn and Uncaria gainbir ; of tho Indian Myro &dans, the mimosa or wattle bark of Australia, the cork tree bark of Spain, and willow bark. Catoctin has long been employed In India for tanning skins, and its tanning properties are so great that skins aro tanned by it in five days.
The Czesalpinia coriaria, or Divi-divi, WM intro duced into India by Dr. Wallich in 1842. The produce of the k i no tree (Pterocarpiia mansupium), and catechu of the betel palm, are also employed. Dr. Ileyne states that the morocco manufactured at Hurryhur was treated with salt and a mixture of water, and the milk of wild cotton (Calotropis gigantea).
In many parts of India the hides are so removed as to form a bag, into which the tan is placed, and the filled bag kept suspended for several weeks. Such leather is soft and flexible, and looks tolerably well, but it resists the rain indifferently, is easily penetrated by wet, and during the S.W. monsoon becomes as moist and flexible as paper clipped in water. When set aside it becomes mouldy, aud very easily rots.
The following are tho.principal of the tanning plants of Southern and Eastern Asia :— Divi-divi, c.atechu, tanghedu bark, etc., produce their effect rapidly, and the leather is durable.
The bark of Baultinia variegata is made use of it.9 a tanning substance in Sind and other parts of Asia. The bitter astringent bark mad the galls of several of the tamarisk tribe aro also well suited for the purpose.
The Tenasserim Provinces are rich in materials for tanning. The bark of the careya, and of half a dozen different species of mangrove, the fruit of the sea-cocoanut, and the peel of a species of ebony, all abound in tannic acid.
All attempts to hurry the leather-making pro cess beyond a certain point, by the use of concen trated solutions of tan, ete., are for the most part failures, as the manufacture of good leather to a great extent depends on the process being con ducted in a slow and gradual, but at the same time thorough and complete manner.
The currier and tanner of India is known as the Chamar, Chakili, Malla-vadu, Mang. They are held in great disesteem, and are the public execu tioners. The condition of the tanners is similar in Japan, where, as in India, they are restricted to a particular locality, and are similarly employed.
—Wilson; Heyne's Tracts; Simnionds' Conant. Pro ducts; Prof. Solly in Jury Reports of Exhibition, 1851 ; Madras Exh. J217'. Reports ; Stewart.