The Morocco leather (so termed from its being the same description of article as was formerly imported from the kingdom of Mcirocco,) is distinguished into two kinds; one being made from deers' and goats' skins, which kind is by far the most durable and beautiful in appearance, and often called "real Morocco;" the other from sheep skins, which, from being only about one-third the price of the real, and being artfully made to imitate the other, by the dressing and finish, is most extensively used for book-binding, shoes, coverings to desks, fur niture, and an infinite variety of purposes. The leather is thus made :—The skin, cleansed and worked in the way already described, is taken from the lime water, and the thickening thereby occasioned is brought down, not by bran liquor, as in tawing, but by a bath of dogs' or pigeons' dung diffused in water, where it remains until sufficiently suppled, and until the lime is quite got out, and it becomes a perfectly white clean pelt. If intended to be dyed red, or any other colour, the opposite edges of the skin are brought together and sewed up very tight, forming an irregular close bag, with the grain side of the skin out wards, as this side alone receives the dye ; therefore, if there are any holes in the skin, they are also sewn up that the dye may not get inside the bag and dye both sides of the skin. The temperature of the bath should not be greater than the hand can bear, when the skin bags may be thrown in, which float upon the surface, the dyer working them about with a rod until they have imbibed the dye uniformly. The proper management of this process requires much skill and experience, some colours,particularly the compound, requiring two or more baths to obtain the required hue. The cochineal and Brazil reds are usually passed through a weak bath of saffron, which heightens the brilliancy of the colour, and gives an agreeable odour to the skins. After dyeing, the skins are tanned in a large vat containing a warm infusion of sumach, wherein they are kept for some hours, until they are sufficiently tanned. Those skins that are intended to be black, are first tanned in sumach, without any previous dyeing, as the sumach (or the gallic acid contained in it) acts as a mordant, to strike a black colour by the addition of a solution of iron, which is rubbed over them by a workman with a stiff brush.
The next processes are polishing and graining; they are performed either by hand or by machinery,, and are technically called finishing. When per formed by hand, the workman takes a skin and lays it before him upon an inclined mahogany table, the highest side of which is upon a level with the workman's middle, and the opposite side about a foot lower, in order that the weight of the body may assist in giving effect to the polisher; this is a ball of glass cut into polygonal surfaces, with which the workman, holding it between his fists, rubs the surface of the skin uniformly from the higher part of the table to the lower, the weight of the upper part of the body being the principal force applied : the skin being held by its edges overhanging the highest side of the table against which the man presses during the work. This polishing or glazing of the surface, (which greatly improves the appearance of the article,) being done, the graining is proceeded in. For this purpose the workman employs a ball of hard wood, usually box or lignum vibe, around which, equa tonally, are cut a series of equidistant parallel grooves, producing thereby an alternating series of projecting parallel ridges ; with these ridges the workman scores the skin all over in parallel lines, and when that is done he shifts fig, skin a little, so as to cross the first lines at a very acute angle, with his ridged ball; which he does uniformly over the skin, and thus produces a regularly corrugated surface.
In the application of machinery to the operations of polishing and graining, the principal difficulty to be overcome was to make the action accommodate itself to the varying thickness, hardness, and texture of the skin ; for the neces sary quantity of force to grain the firm parts of the skin, would, if applied to the tender parts, tear them ; and unless the machine possessed a very sensible degree of flexibility, the prominent parts would get severely rubbed or struck, while the depressed parts would not get touched, or be but slightly acted upon.
annex a description of the earliest invention (about twenty-five years ago) for this purpose, which has been in use ever since.
Hebert's Patent Leather-finishing Machine.—This essentially consists of a very stiff circular frame or wheel, 8 feet in diameter, revolving horizontally on a vertical axis. On the under side of the periphery of this wheel are fixed, in suitable carriages, a series of circular polishers or grainers, according to the nature of the work to be done : the carriages being provided with proper means of adjusting the position of the rubbers with great exactness, and of readily fixing, unfixing, and changing them, according to circumstances. These rub bers, in their revolution, pass directly over a series of eight tables, circularly arranged underneath them. The upper surfaces of the tables are all brought to one true horizontal plane, parallel to the plane described by the under surfaces of the rubbers in their revolution. The skins to be polished or grained, are placed on these tables, one on each, and if they were all perfectly equal in thickness, tenacity, and texture, very little more would be required to make such a machine work ; but as the skins differ in every possible degree in those qualities, the tables are mounted upon elastic bearings, and are further sup ported by a lever to each, at the end of which lever is a step or needle, whereon the workman stands, either with both feet or with one foot only, that he may temper the force according to circumstances, or the nature of the work under operation ; and when he steps entirely off the lever, the table falls below the level of theof the rubbers, and therefore out of action. When the man is on the step, the surface of the table over which the rubbers act, approaches within the hundredth part of an inch of the plane described by the lower sides of the rubbers, so that when a skin is interposed, the thinnest parts are operated upon, and with a force as slight as the workman pleases, and the thick and tough parts with any greater pressure at the direction of the operator. For attaining and preserving a very true plane on that part of the table over which the polishers and grainers traverse, that portion of it is made of brass with adjusting screws underneath. The extremities of this metallic portion are gra dually lowered a little from the true plane to prevent the rubbers striking the skin as they pass in rapid succession on to or off their work. A workman, who stands before each table, spreads the skin upon it, and keeps constantly shifting it after each rub it receives, till it has all been operated all over alike in parallel lines ; he then turns the skin a little sideways, so that the grainer. pass over the previous lines at an acute angle, as before mentioned in the hand work. The glazing and graining of leather may thus be performed in an equal, if not a superior manner to that of hand finishing, and at about one-tenth the cost. Owing to the ground rubbers not being properly chamfered off towards their edges, and to the irregular movements of the skin over the table, by unpractised operators, the skins were at first occasionally scored, showing in a disadvantageous manner the curved lines upon its surface. These defects were soon remedied by atten tion to the points mentioned, and the work afterwards executed was upon the whole of a superior description; for it will be readily conceived, that with so great a radius as 4 feet (the wheel being 8 feet in diameter), the curvilinear form of the lines so close together, and crossing each other, so as to form minute lozenge shaped projections, would appear to be straight; and that if a scratch be made across a skin, it would equally mar its beauty, whether it were in a straight or a curved line. However, a gentleman of great talent (Mr. Joseph Ellis) subse quently conceived the idea of a finishing machine that would groove the skin in straight lines ; and it was constructed with great accuracy and beauty of work manship by Mr. Alexander Galloway, who joined Mr. Ellis in a patent for it. Whether this machine was ever brought to work to advantage the writer is not informed, or has no recollection, but it appears to him to be of a character deserving of notice in this place.