THE TANNER.

The art of the Tanner, consists in converting the gelatinous part of the skins of animals, into the substance called leather, by impregnating it with tannin, or the tanning princiciple, in such a way as to render it tenacious, durable, and impenetrable to water.

It is difficult to say at what period the art of tanning was discovered. It was doubtless known to the ancients in some degree of
perfection ; and it is highly probable that the skins of animals were employed by man as a covering, long before the art of tanning was known : but they would require, in this state, to be constantly kept dry, as moisture would soon bring them into a state of putrefaction.

The astringent matter which converts the akin into leather, abounds in so many vegetables in every country, that accident would soon lead to some method of producing the change. Independent, however, of vegetables, many earthy and metallic substances have the property of rendering skins incorruptible to a .certain extent ; and some mineral waters, containing copper or iron, will occasion this change. Hence we may conclude that some means of giving preference to the skins, must have.been known at a very early period.

Though there has been no radical alteration, or any great practical improvements in the art of tanning, yet for the last twetity or thirty years, it has attracted the attention of many celebrated chemists and philosophers in all countries, who have investigated the subject with great accuracy and precision. Previous to this period we occasionally find some experiments and observations by men of science on the materials of tanning, A variety, of patents has also been obtained in this country for improvements in the art of tanning, but we cannot speak of them as having effectuated much important advantage to the art. The last patent is one which promises, according to the specification, to shorten the time, and improve the process of tanning ; and if the assertions of the Patentee, W. A. Ronalds, of Hammersmith, be correct, leather, by his process, can be tanned in a few weeks. An account of this patent may be seen in the Monthly Magazine for July, 1818.

All tanned leather is classed and universally known under two general denominations : namely, hides and skins. The former being
commonly applied to the larger animals, as bulls, oxen, cows, &c. whose skins are chiefly intended for the soles of stout shoes, and other purposes, requiring very thick and solid leather; while the latter term is used for calves' seals' skins, &c, which being thinner
and more flexible, are intended for the upper leather of shoes and boots, for saddles, harness., &c.

The stoutest and heaviest of the bull and ox hides, are generally selected to make what are technically called butts or backs, and are manufactured in the following manner :

When the horns, &c. have been removed, the raw hides are laid in a heap for two or three days, and are then suspended on poles
in a close room, called a smoke-house, which is heated somewhat above the eommen temperature by a mouldering fire ; this occasions incipient putrefaction, which loosens the epidermis, and renders the hair, and other extraneous matter, easy of separation from the true skin. This is effected by extending the hide, on a wooden horse or beam of a convex form and acraping it with a large two-handled knife, called a fleshing-kmfe, which is bent to suit the convexity of the beam. The hides are then immersed in a pit, containing water slightly impregnated with sulphuric acid. This operation, which is called raising, by distending the pores and swelling the fibres, prepares the hide for the reception of the tanner, and renders it more susceptible of its action. When the hides are sufficiently raised, they are removed into a pit, in which they are laid smooth with a layer of oak bark, ground to a coarse powder, between each.

The pit is then filled with the tanning lixivium, or ooze, prepared from oak bark and water, and the hides remain a month or six weeks without being moved. At the end of this time the tanning principle being exhausted, the ooze and spent bark are taken out of the pit, and the hides put in again in the same way with fresh bark, and covered with fresh ooze as before. Here they remain ahout three months, when the same process is repeated at about the same intervals, three, several times or more, according to the strength of the lixivium, and the substance of the hides. When sufficiently tanned, they are taken out of the pit, hung up in a shed to dry gradually, and being compressed with a steel instrument and beaten smooth to render them fine and dense, the operation is complete ; and, having been numbered, and weighed and stamped by the excise officer, they are ready for sale, and are termed butts or backs.

Crop hides are thus manufactured. The horns having been removed, the hides are immersed in pits, containing a mixture of lime and water, where they remain three or four days, being occasionally moved up and down that every part may be uniformly exposed to the action of the lime-water. They are then taken out of the lime-pits, and the hair and other extraneous matter being scraped off, on a wooden beam as before described, are washed in water to free them from the lime: and filth adhering. They are now immersed in a weak ooze, and by degrees are removed into other pits containing solutions, gradually increasing in strength during the time that they are taken up and put down, (technically termed handling,) at least once in every day, that all the parts of the hide may be acted upon by the tanning principle equally and uniformly. This is continued for about a month or six weeks, when they are put into other pits with stronger ooze, and a small portion of ground bark ; whence, as the tannin becomes exhausted tbey are removed to other pits in regular succession, with fresh ooze and fresh bark for two or three months.

At the end of this period, the hides are put into larger vats called layers, in which they are laid smooth in a lixivium of greater strength, and with a larger quantity of ground bark between each fold. Here they remain about six weeks, when they are taken uip and relaid in the sajne manner, with fresh bark and strong ooze for two months. This procees is repeated with little variation onee, twice, or thrice, at the discretion of the manufacturer, till the hides are thoroughly fanned when t hey are taken out of the pits, suspended on poles to dry, and being compressed and smoothed nearly in the same manner as before described, are called crop hides, and form the principal sole leather of England.

The process of tanning calves'and seals' skins, &c. is somewhat different. They are continued in the lime pits for ten or fifteen days ; they are then deprived of their hair and washed in water, after which they are immersed in an infusion of pigeons' dung, called p grainer, having the property of an alkali. In this they remain for a week or ten days, according to the state of the atmosphere, and
other circumstances, during which titne they are frequently haudled and scraped on both sides upon a convex wooden beam. This
scraping, or working as it is termed, with the action of the grainer, helps to discharge all the lime, oil, and saponaceous matter, and renders the skins soft and pliant, and fitted to imbibe the tanning principle. They are now removed into pits containing a weak solution of bark, where they undergo nearly the same process of handling, &c. as crop hides; but they are seldom placed in layers : and the time occupied in tanning them is usually from two to four months, according to their nature and substance. The skins are then dried and sold to the currier, who dresses and blacks them for the upper leathers of boots, shoes, for harness, and various other purposes.

The light and thin sort of cow-hides and horse-hides, undergo nearly the same process in tanning as calves' skins, and are applied to similar uses.

Tanned leather is subject to a heavy excise duty, amounting to threepence per pound. Tanners are obliged to take out an annual
license from the board of excise, and are besides subject to a variety of fiscal regulations and penalties, which, for the honour of a free state, and the advantages of trade, it would be well if they did not exist.

The trade of a tanner canot be carried on without considerable capital; and a roomy yard, sheds, and pits, with plenty of water, are indispensable requisites.