Several schemes have been devised for forcing a tanning solution through the pores of the hide by mechanical pressure. Mr. Spils bury patented a method of forcing the tan liquor into the pores of the hide by hydro static pressure, but in a mode which was found to produce leather of unequal quality. Ano, ther process, by Mr. Drake, consisted in sewing two skins together (after they had received a slight tanning in the ordinary way), so as to form a water-tight bag, which was filled with tan-liquor, and compressed so as to force the liquor through the skin. In another plan, which has been tried under several forms, the tanning liquid is applied to both sides of the hides, which are placed in an air-tight vessel, and is forced into their pores by hy drostatics pressure, the air being previously pumped out. In the plan patented by Messrs. Ilerapath and Cox of Bristol, a number of hides are connected together by strings, so as to form a continuous belt, and passed between rollers turned by steam or otherpower ; there are several pairs of rollers, each pair erected over a pit. The pits contain tanning liquors of different degrees of strength. The hides are dipped first in the weakest liquor and so on to the strongest, passing between and being compressed by the rollers after each dipping. This process is said greatly to expe dite the conversion of hide into leather ; but it is not yet settled whether the leather is of quality equal to that prepared by the old method.
The thinner bides or skins for the upper teathers of boots and shoes are tanned with the same materials as the thicker, but by a quicker and less elaborate process.
Of the thin skins prepared for ornamental purposes, many are tanned with a substance called sumach, prepared from a plant of the same name. After a preparatory cleansing, &c., the goat-skins for morocco leather are sewed up into the form of a bag, with the grain or hair-side outwards ; they are nearly filled with a solution of sumach, inflated with air, the aperture tied up, and the bags then thrown into a cistern of hot sumach liquor. Being thus acted on, both within and without, the skins are soon impregnated with sumach. The bags are then opened, the liquor removed, and the skins washed, rubbed, dried, dyed, and wrinkled by pressure with a grooved instru ment. Cheap or imitation morocco is made of sheep -skins.
Taiping is the name applied to the process by which the skins of sheep, lambs, and kids, are converted into soft leather by the action of alum. Of this kind of leather gloves are usually made. Skins intended for tawing pass through a series of operations resembling those by which skins are prepared for tan ning ; but the tawing materials consist of alum, salt, flour, and yolk of eggs (chiefly the first two), which are applied in various ways. The skins require a great deal of stretching and rubbing after the steeping, to give them the requisite softness.
In making Chamois Leather or Shamayed Leather, of which wash-leather is a cheap example, the skins of deer, goats, and sheep, are impregnated with oil instead of with the ingredients hitherto mentioned. After a certain preparation, the skins are beaten for many hours with heavy wooden machines, and eod-oil is forced into the pores.
Sheep-skins, when simply tanned, are em ployed for inferior bookbinding, for leathering bellows, and for various other purposes for which a cheap leather is required. All the
whit-leather, as it is termed, which is used for whip-lashes, bags, aprons, &c., is of sheep skin ; as are also the cheaper kinds of wash leather, of which gloves, under-waistcoats, and other articles of dress, are made. Mock or imitation morocco, and most of the other coloured and dyed leathers used for women's and children's shoes, carriage-linings, and the covering of stools, chairs, sofas, writing-tables, &c. are also made of sheepskin. Lamb-skins are mostly dressed white or coloured for gloves ; and those of goats and kids supply the best qualities of light leather, the former being the material of the best morocco, while kid leather affords the finest material for gloves and ladies' shoes. Leather from goat skins, ornamented and sometimes gilt, was formerly used as a hanging or covering for walls. Deer and antelope skins, shamoyed or dressed in oil, are used chiefly for riding breeches. Horse-hides, which, considering their size, are thin, are tanned and curried, and are used by the harness-maker, especially for collars ; and occasionally, when pared thin, for the upper leathers of ladies' walking shoes. Dog-skins are thick and tough, and make excellent leather. Seal-skins produce a leather similar but inferior to that supplied by dog shins ; and hog-skins afford a thin but dense leather, which is used mostly for covering the seats of saddles.
Currying is the general name given to the various operations of dressing leather after the tanning is completed, by which the requi site smoothness, lustre, colour, and supple ness are imparted. The processes of the currier are various. The first is styled dip ping the leather. It consists in moistening with water, and beating upon a trellis-work of wooden spars, with a mallet or mace. After this beating, by which the stiffness of the hide or skin is destroyed, it is laid over an inclined board, and scraped and cleaned, and, where ever it is too thick, pared or shaved down on the flesh side, by the careful application of various two-handled knives ; and then thrown again into water, and well scoured by rubbing the grain or hair side with pumice-stone, or with a piece of slaty grit, by which means the bloom, a whitish matter which is found upon the surface in tanning, is removed. The leather is then rubbed with the pommel, a rectangular piece of hard wood, about twelve inches long by five broad, grooved on the under surface, and fastened to the hand. The currier uses several of these instruments, with grooves of various degrees of fineness, and also, for some purposes, pommels' of cork which are not grooved at all. The object of this rubbing is to give grain and pliancy to the leather. The leather is then scraped with tools applied nearly perpendicular to its surface, and worked forcibly with both hands, to reduce such parts as may yet be left too thick to a uniform substance. After this, it is dressed with the round knife, a singular instrument which pares off the coarser fleshy parts of the skin. In addition to these operations, the currier uses occasionally po lishers of smooth wood or glass for rubbing the surface of the leather; and, when the leather is intended for the use of the shoe maker, he applies to it some kind of greasy composition called dubbing or stuffing.