英文科學(xué)讀本 第六冊(cè)·Lesson 36 Leather—Skins

Lesson 36 Leather—Skins

We have already dealt with the preparation of hides— that is, the skins of large animals, such as the ox, horse buffalo, antelope, etc. —for the heavier, thicker kinds of leather. But besides these there are many varieties of thin light leather, made from the skins of the goat, kid, sheep, and lamb; such as are used for kid gloves, bags, purses, pocket-books, linings for hats, and a host of other purposes. These leathers are prepared, not by tanning, but by another process known as tawing.

For this purpose the skins, after being prepared in the usual way, are first soaked in a solution of alum and salt, and then in a liquor made of wheaten flour mixed with the yolk of eggs. The alum and salt by combining with the gelatine of the pelts does the work of the bark ooze in tanning, while the yolk of eggs and the flour give this kind of leather its peculiar softness and elasticity.

The consumption of eggs for this purpose is so great that it is no uncommon thing for some of the great leather factories in Bermondsey to have at one time as many as 100,000 eggs in store, preserved in lime and salt.

The skin of the sheep is sometimes tawed whole; sometimes it is split into two distinct skins before the tawing process is begun. The unsplit or whole skin in its finished state is called roan. It resembles morocco, but is less expensive, and is largely used by bookbinders.

Sheep-skin leather is also extensively used in the manufacture of trunks and bags, pocket-books, purses, linings for hats, boots and shoes, cases for jewellery, musical instruments, men's braces, etc.

When it is split into two skins the grain or outer one is known as a shiver, the under one is called a flesher, The fleshers of sheep-skins are largely used for the manufacture of military gloves, and for wash-leather.

Wash-leather was formerly made from the skin of the chamois-goat; hence it is frequently styled chamois, shamoy, or shammy leather.

Large numbers of sheep-skins are converted into mats and rugs. For this purpose they are tawed with the wool on them. The process of preparation is very simple. All that is necessary is to carefully scrape away every little particle of flesh and fat from the skin, stretch it out flat upon a board with a few tacks, the woolly side downwards, and then rub the surface of the skin itself with a mixture of powdered alum and salt repeatedly for a few days.

The alum and salt are readily absorbed into the gelatine of the skin, and convert it into the new substance— leather. The best of the skins are afterwards treated to a dressing of the flour and yolk-of-egg liquor, to make them supple and pliant.

Parchment is made from the skin of the sheep, goat, and young calf. Rams' skins supply parchment of excellent quality, but that made from lamb-skins is best. Vellum, a very white, fine, and smooth kind of parchment, used mostly for important documents, is prepared from the skin of the young calf.

The heavier kinds of men's gloves, known as dog-skin gloves, are made from the skin of the South African sheep.

Lamb-skins are always tawed unsplit, as they are too thin to bear splitting. From them is made a soft white leather, known as beaver, which is used largely for making the cheaper sorts of white kid gloves.

Goat-skins are chiefly used in the manufacture of morocco leather. The skins for this purpose are dressed with shumach. The Moors of Northern Africa long held the complete monopoly in this manufacture, but the tanners of Europe have now not merely learned the art, but actually surpassed the Moors themselves in the quality of their production.

Morocco leather is used only for ornamental purposes, and is always dyed either red or bright yellow. An inferior morocco is made from sheep-skins. Kid-skins are always used for the best kid gloves.

It is estimated that England's own slaughter-yards yield annually 17 million sheep and lamb skins, and imports from other countries supply 10 millions more. The largest shipments of these skins come from South African colonies.

The number of goats reared in the United Kingdom is not large, but they annually import about 7 million goat-and kid-skins, most of which come from India and South Africa.

Woodstock has long been noted for its gloves, but the trade has declined of late years, except for military and hunting gloves. The glove manufacture is mainly located now in Yeovil, Worcester, and London. Limerick carries on a brisk manufacture and trade in soft, delicate gloves— so thin and fine that it is a common thing to pack a pair of them in a walnut shell for sale.

Immense quantities of foreign gloves are imported, mostly from France—the French gloves being specially sought after, both for the quality of the kid and the excellence of the workmanship. Indeed, the glove manufacture in France is a very lucrative branch of industry. It is estimated to yield an annual output of more than 30 million pairs, worth from ￡3,000,000 to ￡4,000,000 sterling, and to give employment to about 90,000 persons.

Russia leather is well known by its pleasant smell, which, however, moths and other insects do not like. It is used for binding valuable books, and for making many varieties of articles for use and ornament. It is tanned with willow bark, and afterwards treated with a kind of tar made from birch bark, but the actual process of manufacture is kept a secret.