Leather
2 of the 7 encyclopedias on this shelf carry an entry for Leather. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
the skins of animals chemically modified by tanning and otherwise, so as to arrest that proneness to decomposition which characterizes unprepared skins, and to give to the substance greatly increased strength, toughness, and pliancy, with insolubility and unalterability in water. Remains exist of tanned leather made in Egypt not less than 900 years B. C. There are three methods by which leather is prepared: first, and by far the most important, with tan barks and other vegetable substances containing tannin; second, by tawing with alum, bichromate of potash, and other mineral salts; and third, by shamoying or impregnating the raw skin with oil. The skins of all animals used for leather making consist chiefly of a fibrous gelatigenous substance called collagen, which on being boiled forms the ordinary gelatin of commerce, with an interfibrous compound called coriin, insoluble in water, but which in common with collagen unites with tannin to form the insoluble and unalterable compound tanno-gelatin, the chemical basis of tanned leather. The skins of all animals may be made into leather; but in practice the raw materials of the manufacturer consist of the skins of certain animals which are reared and slaughtered primarily for other purposes, and of which the supply is sufficiently large to form the basis of a great industry. Large skins, it may be remarked, such as those of oxen and horses, are in trade termed hides; those of calves, sheep, goats, and other smaller creatures are called skins. Of all leather-making hides the most important are those of oxen, which are primarily distinguished as ox, cow, and bull hides, and calf skins. Leading sources of supply are Australia, the Cape of Good Hope, the River Plata and South America generally, and China and Japan. From the East Indies there come vast quantities of small hides termed kips, both salted and tanned. Buffalo hides are imported in large quantities from Singapore, Batavia, Bombay, Kurrachee, and Calcutta. Horse hides are brought in considerable quantities from South America. Sheep skins, from the vast quantities yearly available in nearly all parts of the world, are a most important source of leather. Goat skins and kid skins come from dies, Asia Minor, and Switzerland; but the Cape, the East Inmany of skins are when imported already tanned, the East Indian and Asiatic and require which have only a local or a limited only dressing. Other skins market are the walrus, rhinoceros, and elephant, from which leather of great thickness, suitable for polishing wheels and other mechanical purposes is obtained; and hog or pig skin is an important source of leather for saddle making and other purposes. The skins of various species of deer and antelope, porpoise and kangaroo, are also sources of leather; and from the Cape there are occasionally sent to the London market skins of the gnu and quagga. As sources of leather for fancy articles there may be mentioned the alligator (a leather now extensively imitated), and certain snakes' and sharks' skins. Tanning. The operations of tanning and the duration of the process vary very widely. Oak tannage is a very tedious process, and the common practice is now to hasten the completion of the operation by mixed tannage, in which more rapidly acting agents play a part. In the United States hemlock bark from Abies canadensis is the most important tanning material; and the mimosa or wattle barks of Australia are very largely used in the British colonies as well as in Great Britain. Standard extracts containing a fixed percentage of tannin have also come into favor for rapid tannage. But, with all the devices which have been suggested, tanning is essentially a slow operation. The great amount of poor leather in the markets is due to hurried preparation and use of chemicals that injure the texture. In the treatment of ox hides for the production of, say, sole leather, the first object of the tanner is to clean and soften the hide. This is done by washing with water, and if necessary working the hide under stocks till the whole is uniformly soft and pliant. The unhairing and removal of the scarf skin is the next operation, for which in English tanneries the hides are steeped in pits containing lime water, while in the United States the Alpine ch plan adopted consists of sweating the consists pr hides, or artificially heating them till inset sheep ski skin cipient putrefactive fermentation is of stock sl up. The hides are afterward stretched skin and over a tanners' beam, and the hair and ing a kind scarf skin are removed by shaving with a fleshing knife. At the same time the tinous cor liarly soft flesh side is gone over, and any fragments of fiber or fat adhering to it are LEAVE pared away. All traces of lime in the seat of L hides must be got rid of, and that some- Missouri z times is effected in the first tan pit, conand Santa sometimes by "bating" in "pure" which Chicago, Rock Island and Pacific and taining acid liquors weak in tannin, and Chicago, I several oth is a warm decoction of pigeons' or other Kansas C fowls' dung. The method of actual tana farming ning varies endlessly, but in general it factures may be said to consist in suspending or machinery depositing in layers the hides in a successive series of pits containing tan wagons, b iron bric liquor or ooze which is weak at first, but brooms. which as the tanning proceeds is made increasingly rich in tannin. To finish the softened Academy, hides they are damped and in Whittier water, scoured to remove the bloom from United S their surface, then liberally oiled and the electzia i whole surface worked over by pressure a three-sided steel implement called excellent with a striking pin. This operation removes all creases and smooths out and solidifies the leather-an operation carried further and finished after renewed oiling, by Adjoining rolling the hide on a smooth floor under LeavenwO a heavy hand roller. Morocco leather is Zantry an al comete a term which now applies rather to the 16,912. finish of a certain class of goods than to LEBAL the source of the skin of which it is county se formed. It is a richly grained and dyed Cleveland leather, originally and properly made from goat skins tanned in sumach. Louis and Its indus Sheepskins roughly tanned and undressed are termed basils; dressed and factories, elevators. dyed as for morocco, but finished smooth, (1920) they form roans; and split sheep skins (the flesh sides of which go to be sham- LEBAT oyed to form wash leather) tanned and dressed are known as skivers. Russia the count the Phils leather is now any smooth finished thin wall, and leather, impregnated with the empyreu- POДOB. matic oil of birch bark, which gives the substance its peculiar odor and insect posits o brick cla resisting qualities. Originally it was made in Russia of dressed calf skins. industrie Tawing. Tawing consists in dressing brickmak skins with certain mineral salts, and is useful principally for glove leathers and silk, bolts four libr the so-called kid leather employed for the also uppers of ladies' boots. It is by public b (1920) 2 tawing that furriers' skins are prepared, and hides and skins in the hair generally LEPA Syria. preserved. Shamoying. This consists simply in impregnating and saturating skins with つな oil. The name is derived from the fact tains, that the process was originally applied their for the preparation of the skins of the logically Alpine chamois. Shamoy leather now leather now consists principally of the flesh splits of spiita of sheep skins. The oil is worked by means worked by means of stock slowly into the interstices of the interstices of the skin and there becomes oxidized, formoxidized, forming a kind of combination with the gelaation with the gelatinous constituents, and yielding a pecuyielding a peculiarly soft and spongy texture. zy texture.
Aiton's Encyclopedia (1910)
the skin of an animal dressed by a process called tanning. The skins of the cow, ox, buffalo, elephant, and other large, thick-skinned animals are called hides, as distinguished from the skins of calves, sheep, goats, dogs, and fur-bearing animals. Kip leather is produced from the hide of a half-grown animal. Green hides are rubbed with salt to prevent putrefaction, or else they are dried before they are sent to market. Both green hides and dried hides may be converted into glue by boiling. So far as the art of tanning is concerned, all skins and hides consist of three layers,--the outer or epidermis, including the hair; an inside fleshy, fatty layer; and a third, or intermediate layer between the two, out of which leather is made. The preparation of leather consists of two entirely distinct processes. First, getting rid of the hair and the flesh; second, filling the central layer with curative and preservative material. Skins valued for their fur are, of course, dressed and tanned from the flesh side only. There are many ways of removing the hair and fat. One of the simplest consists of laying the hides in a bath of milky limewater for from two to twenty days, which loosens the epidermis and hair, and forms a kind of soap with the fatty matter. During this process the hides are turned over frequently and are churned about to make sure that the lime reaches all parts. Working or handling, as it is called, also assists in breaking up the epidermis and fatty cells. When taken out of the lime bath, the hides are scraped both inside and out with knives until nothing is left but the fibrous portion of the hide. The skins are now ready for the real process of tanning which converts them into leather. This may be done by immersion in a vat containing liquor strongly impregnated with tannin,--a strong coffee-like liquid obtained from the ground bark of oak, hemlock, birch, beech, or from the leaves and shoots of the sumac. The wood of a tree found in Argentina yields a fourth of its own weight of tannin. The more the hides are handled during this process, the more flexible and soft the leather. This treatment is continued for from one to six weeks, and then the hides are shifted into a second vat containing a still stronger decoction of tannin. To obtain the best results, the tanning process should continue for eight or ten months. After this the skins are worked thoroughly over a beam, and are shaved carefully on the flesh side to a uniform thickness. They are then filled with a mixture of oil, soap, and tallow, thoroughly worked in by a prolonged tumbling about in a revolving drum. There are shorter methods, but they do not produce as durable leather. Leathers intended for the uppers of boots and shoes are blackened on the hair surface with a mixture of lampblack and oil or tallow. The treatment of sole leather, intended for the soles of boots and shoes and similar purposes, is more simple, as a less degree of flexibility is desired. In place of tannin from vegetables, a tanning solution is made of certain minerals compounded of alum, salt, sulphur and other elements. Well tanned leather is flexible, soft, tough, and proof against all forms of bacteria; that is to say, it will not putrefy under any circumstances. Leather exposed to moisture, however, especially in a dark place, will mold. Tanning is at bottom any process that renders the fiber proof against the attacks of bacteria; that is to say, against putrefaction. This may be accomplished also by a process called oil tanning. Oil-tanned leather is leather in which the tanning bath is omitted. The skins are pounded, rolled, and pressed in oil until every particle of animal matter capable of putrefaction has been driven out and replaced by preservative oils, chiefly those of the whale or cod. The Indians tanned their buckskins by filling them with the oily brains of the deer. Chamois leather is tanned in oil. Morocco leather is tanned with sumac and stained with dye. Patent leather is made by splitting a skin into thin layers and coating them with a varnish of linseed oil containing lampblack and some other coloring matter, as Prussian blue. Parchment is made from the skin of sheep from which the flesh and hair have been removed in the usual manner. It is then stretched on a frame, and putrefying matter which it contains is absorbed by powdered chalk, after which the surface is smoothed with pumice and scraped with a steel blade. The skin is then dried and smoothed into shape. Vellum is made in a similar manner. The making of leather is an ancient art preceding the dawn of history. The Egyptians tanned leather certainly 3,000 years ago. The United States leads the world in the production of leather. 600 tanneries produce one-fourth of the world's supply. Every year nearly 200,000,000 hides and skins pass through these 600 tanneries, and when finished into leather they are worth $250,000,000. It requires 1,250,000 cords of tanbark and 650,000 barrels of extract to meet the demands of the American tanner in the conversion of these hides and skins into leather. Two-thirds of the tanbark used is from the hemlock tree. Philadelphia is noted for the production of kid leather from the skin of the goat and substitutes. A quarter of a millon alligator hides are said to be tanned yearly at Newark, New Jersey . See Buckskin ; Morocco ; Boots And Shoes ; Gloves; Pergamus