If the removal of the lime be the only object aimed at in bating, the ordinary process is most wasteful, as well as dis gusting, from the loss of pelt it entails. It is easy to find chemical reagents which will remove the lime ; but the resultant leather has been found wanting in softness, and it is probable that the solution of the inter cellular matter is in many cases advan_ tageons.
The bating required may, however, be shortened, and probably with advantage, by washing the hides with warm water in a " tumbler," or rotating drum, Fig. 917, prior to putting them into the bate, or the whole bating may be done in the tumbler. After a short bating, also, the hides may be softened and cleansed by stocking for 15-20 minutes.
Various machines have been proposed to take the place of hand-labour in the beam work, and, at least as regards the smaller skins, with considerable success. As a type of these, may be mentioned Molinier's bide-working machine, Fig. 906, which consists of a drum covered with helical knife', rotating at a speed of about 500 rev. a minute, over a oylinder coated with indiarubber. The skin is allowed to be drawn in between these drums, and the two being pressed together by a treadle, it is drawn out by a mechanical arrangement in a direction contrary to the rotation of the knives, which scrape off the flesh, or work off the hair.
After bating, " shaved " hides are reduced in thickness in the stronger parts by a shaving-knife, on an almost perpendicular beam. The workman stands behind the beam, and works downwards. The knife is represented at A, Fig. 903, and is a somewhat peculiar instrument. The blade is of softish steel, and after sharpening, the edge is turned completely over by pressure with a blunt tool, eo as to cut at right angles to the blade. There ie an obvious economy in shaving before tanning, since the raw shavings are valuable for glue-making, while, if taken off by the currier, they are useless for this. urpose. The hide also tans faster.
Instead of shaving, the untanned hide is frequently split, by drawing it against a rapidly vibrating knife. The piece removed is tanned for some inferior purpose, if sufficiently perfect. In sheep-skins, which are split by a special machine, the grain-side is tanned for French morocco or basil, while the flesh-side is dressed with oil, and forme the ordinary chamois or wash-leather.
Such a machine is shown in Fig. 918.
Tanned leather is usually split by forcing it against a fixed knife, as in the American " Union" machine, Fig. 919.
After bating, scudding, and shaving, the hides are taken into the tan-house, where they are grained, either by fre quent handling, or by working in a paddle-tumbler (a vat agitated with a paddle-wheel), with a liquor of suit able strength, What this strength should be depends on whether a well- marked grain is required or not. The
stronger the liquor, the more it con tracts the hide, wrinkling the surface into a network of numberless crossing furrows, which form the well-known marking of " grain-leather." In bark tannage, the after management is much like that described with sole-leather, except that weaker infusions are employed, and acid liquors, which would swell the hide and produce a harsh leather, are avoided. In old-fashioned country yards, which produce some of the best bark - tanned shaved hides, the liquors rarely range above 10°-15° of the barkometer, and the time employed is 3-6 months. The hides, after passing through a set of handlers, of gradu ally increasing strength, in which they are at first moved every day, are laid away with bark liquor and layers of fresh bark, receiving per haps 4-5 layers of 2-4 weeks each. Unfortunately, these tannages are so unprofitable that they are rapidly being supplanted by quicker and cheaper methods.
These more rapid and cheap tonnages mostly depend on the use of " terra " (block or cube gambler) in combination with bark, valonia, or myrabolams. Liquors warmed to 43° or even 60° (110°-140° F.) are employed, and a bright colour is finally imparted by handling in a warm sumach or myi-bolams liquor, which dissolves out much of the colour imparted by terra or extracts. The tannage is helped forward by frequent handling, by working in tumblers, or sometimes by suspension on rocking or travelling frames, after the American fashion.
To this class of tannage belongs that of E. India kips, which is largely carried on in the neigh bourhood of Leeds. These kips are the hides of the small cattle of India, and are imported in a dried condition, and with their flesh side protected (and loaded) with a coat of salt and whitewash or plaster. They arc usually softened in putrid soaks, and unhaired with lime, and are used in England for many of the purposes for which calf-skins were formerly employed. A variety of E. India kips, called " arsenic kips," are treated (instead of plastering) with a small quantity of arsenic before drying, to prevent the ravages of insects, which are often very destructive to these goods. Many kips tanned in India have also been imported of late years, and have greatly interfered with the profits of English tanners.