We might greedy lengthen this list of new processes, but these few will illustrate the whole ; especially, as the old operations of the tan pit have not yet been very extensively departed from in practice. Really good leather is still very slowly made. One inventor has gone No far to employ galvanic agency to drive the tan into the limes of the hide ; but the result Is unrecorded.
Simached leathcr.—Ws have hitherto alluded chiefly to the prepare den of the thick hides used fur soleleether ; but the thinner and weaker bides, as well as the skins of calves and other animals, are also prepared for WOO as upper leathers ; in which case It is necessary to reduce their thickness by shaving or paring them down upon the flesh or inner side, before they are subjected to the action of the tanning inflowns. Such hidva or skins also require, after leaving the hands of the tanner, to be rubbed. softened, and dressed by the currier, in order to bring thorn to the necessary degree of flexibility and smooth ness. Horse-hides, which are comparatively weak and thin, are some time* dressed on the grain side, under the name of cordovan hides, from the circumstance of such leather having been formerly made et Cordova in Spain. Calf-skins supply the kind of leather most gene rally preferred for the nppor part of boots and shoes.
Of the thin skins prepared for ornamental purposes, many are tanned with a substance called sumach, prepared (ruin a plant of the rases D611/6. The most important kind is that called Morocco, which Is med. from gnat-skink In the routine of operations, theprocesses of cleansing the skins from fleshy Impurities, and removing the hair, preemst no material variation from those before described. During therms — processes. the lime employed to assist in the depilation enters the pores of the skin so completely, that it would impede the action of the tanning liquid if allowed to remain. It is therefore removed by fin meraion in an alkaline solution, which opens the pores in a way resem bling the process of raising, described in a previous paragraph. The tanning is then performed b7 sewing up each skin into the form of a bag. with the grain or hairaide outwards, and nearly filling it with a strong solution of sumach in water. The bag is then fully distended by blowing into it, and the aperture is tied up ; after which it is thrown into a large shallow vessel filled with hot water containing a little sumach. The distended bags float in this vessel, and are occa sionally moved about with a wooden instrument, until the solution which they contain has thoroughly penetrated their substance. Owing to the thinness of the skins and the heat to which they are exposed, this operation is performed iu a few hours. The process is expedited by taking the bags out of the solption and piling them upon a per forated bench or rack at the side of the tub. so that their own weight may force the confined liquid through the pores. When the tanning is completed, the bags are opened to remote the sediment of the sumach ; the skins are washed, rubbed on a beard, and dried ; after which they are ready for dyeing and finishing with a ridged instru ment, which imparts to the surface that peculiar grain by which morocco leather is distinguished. An inferior kind of leather, known
as imitation morocco, is prepared in a similar manner from eheep-akins.
Tutted leather Tatting 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 towing pass through a series of preliminary opera tions resembling those by which skins are prepared for tanning ; but they are then subjected to a solution of alum and silt, to which, for the superior kinds of leather, flour and yolks of eggs are added, instead of a vegetable astringent solution. Sometimes the skins are put into a kind of barrel with the solution, and then the whole is made to rotate rapidly, by which the skins are quickly penetrated and in other cases the impregnation is effected in an open tub, the skins being worked in the pasty liquid with the hands, or trampled upon by the naked feet of a man, until the emulsion is thoroughly incorporated with them. They subsequently require a good deal of stretching and rubbing over a kind of blunt-edged knife, and some other finishing operations, to give them the requisite smoothness and suppleness. Many of the gloves sold as kid are really made of lamb-skins, of which considerable numbers are imported from the shores of the Moditerranesn. These are brought with the wool on; and, as it would be injured by the action of slime, it is loosened by inducing fermentation or incipient putrefaction in subterranean vaults or cellars ; an operation which requires_ great nicety, since the pelt would be injured by allowing the fermentation to proceed too far. After the wool has been removed, and the skins have been scraped to free them from a slimy substance which exudes from the pores, the pelts are immersed in lime-water for a few days, to remove the grease which yet remains in them. The subsequent operations of removing the limo, towing, see., are similar to those required for other skins. In taming sheep-skins with the wool on, for housings and similar articles, the wool side is carefully folded inwards, to protect it from the towing liquid or paste, which is then applied to the flesh side only. Alunied leather is made in very large quantities for kid gloves and shoes, real or imitative. The French are skilled in that art. At Annonay, a town about fifty miles from Lyon, the teeing operations are carried on so largely, that 4,000,000 kid-skins are dressed there annually. It has been computed that France and England together consume 6,000,000 eggs yearly. in preparing kid leather. The eggs are kept by the leather dressers in lime-water, to preserve them till wanted fur use.