It may be well here to notice from whence the material used in this country is obtained. Next to the home col lection, the supply derived from Germany, through the ports of Bremen and Hamburgh, is most considerable ; and a great quantity of rags from the Alediterranean is anuually imported, chiefly from Leghorn, Trieste, and Palermo The different nature of these kinds of rags is very striking ; while our home supply consists very much of cotton, and of a finer quality than the rest, that from Germany is a strong linen material, almost all unbleached, but not very fit for the paper-maker, unless bleached with the oxy muriatic acid gas, except the finer kinds, called S i'FF Bremens, which arc perhaps the best material for a fine NvIiting-paper, and which brings a high price accordingly. The Tuscan rags, again, though dirty, acquire a high co lour by the common way of washing, without being bleached, but toe unfit lor the purposes of writing-papers, from the difficulty of making them take the size. A mix ture of the different kinds of rags is most esteemed by paper-makers, as it combines the good qualities of each and, as it were, neutralizes the bad effects which would re sult from using a particular sort unmixed.
The next operation is the (lusting of the rags. A re volving cylinder, about six feet long and four high, cover ed with the same kind of wire-cloth as the tables, is at tached to the machinery of the mill, so that it can be set in motion with considerable velocity. In the axle of this cylinder, spokes, about twenty inches long, are fixed. A part of the circumference opens, and by this door the rags are placed in the duster. The door being closed, it is set in motion. The rags are prevented from remaining in a mass by the spokes, and the dust escapes through the wire-cloth. After being driven about for half an hour or thereabouts, they are taken out to be placed in the engine, and reduced to pulp. This part of the process merits a particular description.
This engine (see Plate CCCCLVII. Figs. 1, 2.) consists of a trough A, 10 feet long, 44 broad, and 21 deep, gene ratly made of wood, but sometimes of iron. If of wood, it must he lined with lead. BB is a division in the engine, dividing it into two sides, one of 26 inches, and the other of 22 inches. CC (Figs. 1, 2.) is the roller, which is com posed of wood or iron, 22 inches in diameter, and 26 inches wide. Along it, and firmly fixed in it, are bars or plates of steel, 1-8th or 1-16th of an inch thick, but taper ing towards the edge, and projecting two inches beyond the wood or iron of the roller. Below the roller is the plate Dll, (Figs. 2, 3.) which slides in a groove exactly under the roller, but not parallel to it. It is composed (Fig. 3.) of bars of the same kind as those of the roller, but placed close together, and 5 inches broad. The roller is supported on the box I, (Figs. 1, 2.) in which is a screw G, for the purpose of elevating or depressing it. Above the roller is a cover, which extends 6 or 8 inches on each side of it. In this cover towards the ends arc two frames (Fig. 2.) I, I, covered with fine wire-cloth, and sliding in grooves in the cover, and leaving a space behind K, K, communicating with the pipes \l, M, (Figs. 1, 2.) Before the frames are two boards, L, L, which can also be removed. We now come to describe the operation. The roller being set in motion by means of the pinion E on the same axle, with a velocity of 160 revolutions in a minute, from 112 to 130 lbs. of rags are put into the engine, with as much water as will raise the whole to within an inch or two of the brim. The roller is depressed till its bars touch those of the plate ; the rags are carried through, bruised on their passage, and the greater part of them arc thrown over the height P. Here they are collected and
pushed round till they arrive again at the roller, are again carried through, and again carried round. This goes on continually. Meanwhile the pipe 0 being opined, water is allowed to run into the engine, and the boards L, L, be ing removed, part of the rags and water are thrown up against the frames I, I ; the water passes through, and off by the pipes Al, M. Thus the rags are bruised down and washed ; at the same time, it is of the utmost conse quence to have a regular supply of spring water. indeed, line papers cannot be made to advantage without this ; a hogshead per minute will be an ample supply for a wash ing and beating engine, which will prepare about six cwt. of rags in a day, if the power of the mill is sufficient to keep them constantly at work. Both engine and roller ought to be made of elm, where iron is not used, which is better, especially for the latter, if there be power to drive them, as its weight makes it go steadier, and thus pre pares a more equal stuff. The engine must be lined with lead, as the head of a nail rusting in it is sufficient to cause great numbers of those red or rusty marks often seen in paper. It is of consequence that the machinery should go equably, a heavy fly wheel is hence advanta geous. The power required for a 5 or 6 vat-mill is about 20 horse. The roller must make from 150 to 160 revo lutions in a minute in the washing engine, and about 180 in the beating. When the rags have been about an hour in the engine they are bleached ; there are two ways of bleaching used at present, one by the oxymuriatic acid gas, the other by the acid combined in the dry with quicklime. In the first way the rags are boiled in an alkaline solution of potash and lime, for four or five hours, or if very coarse, for eight hours The purpose of this is to destroy the coarse part of the hemp, commonly call ed shun or sheave, and which exists in a great degree in coarse linens, especially German rags. The solution is then washed out in the washing engine ; the water being pressed out, they are exposed to the acid, in the gaseous form, as linen is, (see BLEACHING.) The gas is then washed out as carefully as possible ; this is of great im portance, as, if any acid remain in the rags, it causes the paper after some time to putrefy and change its colour. In the other way the oxymuriate of lime is diffused in water by agitation, the insoluble matter is thrown out, and the liquor when clear is diluted and put in the en gine ; being thoroughly mixed with the rags, it is al lowed to stand for an hour or more, and the acid care fully washed out. Bleaching is not now in very common use, on account of the low price of rags. The stuff is then reduced for an hour more in the washing engine, and is then put into the beating engine. The bars of the roller in this engine are placed three together, nearly at the same distance as in the other engines. The plate has from 18 to 20 bars ; it is common to make the plate of brass ; then a greater number of bars, or rather grooves sawn in the brass, are necessary. The process does not go on so quickly with a plate of this sort, but the stuff prepared is clearer. The cover of this roller has only one washing frame, and even that is little used ; this en gine is rather smaller than the other. When the stuff has been beat, as it is called, for about three hours and 'a half, it is generally fine enough, and a valve placed in the bot tom of the engine being opened, the stuff escapes into the chest.