tight, and pipes are conducted into it from a retort, which convey chlorine, formed, by the application of heat, from manganese, common salt, and sulphuric acid. This part requires much care ; for if carried beyond its due point, it proves most injurious to the durability of the fabric. The rags when taken from this chamber are strongly imbued with a most nauseous smell, and require pro fuse and frequent washings. After this process they are put into the beating en gines, and pass through a sort of tritura tion, which reduces them to a coarse and imperfect pulp, which is called half stuff or first stuff, and this is again levigated until it assumes the appearance of cream.
The state and quality of this pulp is of the utmost importance to the final per fection of the paper. If, in the leviga tion, the fibre should have been so en tirely destroyed as to reduce it to a jelly, the paper will inevitably prove liable to break, moulder away, and be rotten ; and this must result whatever be the pre vious excellence of the material. A fibre is absolutely necessary to the production of a servicable paper. Mr. Murray, in a little work on the subject full of practical science, recommends that a small propor tion of unbleached flax should be added to the half stuff—an expedient that would doubtless much increase the strength and durability of the manufacture. But, unfortunately, so far from means being taken to improve its consistency, others are resorted to, for the sake of an in creased profit, which deteriorate almost to destruction : we mean the introduc tion of plaster of Paris, or other earthy substances, into the pulp; and this can never be done without ensuring brittle ness and want of cohesion as the result. While the pulp is in this state, the size, made from sheep-skins and other animal substances, together with a solution of alum, is introduced, excepting only in the manufacture of writing paper, and then the sheets are most generally sized after their formation.
A patent was granted in 1847, in this country, for the mode of making the pulp from straw. The material of straw has long been used for this purpose, but the method of treatment is believed to be new, and is as follows :—The straw, or other vegetable fibrous material, is heat ed or boiled with milk of lime twelve hours, in a suitable boiler, and the lime and coloring matter washed out in a suit able tub. The fibrous matter is then transferred to mill-stones, so arranged us to crush it, and at the end of this opera tion the pulpy matter is again transferred to another tub for further washing out the coloring matter. Theulpy matter is next removed to a set of boil ers, where fresh lime-water and an alka line solution of the strength of two to four degrees of the hydrometer is sup plied, and the heat continued for six hours.
At the end of this time, the whole li quor and pulp are forced up by steam pressure into a third washing tub, where it is washed, and sulphuric or muriatic acid of the ordinary strength used for bleaching purposes, is supplied, and the contents kept in agitation for two hours, and the acid is then entirely washed out. The pulp is next returned to the second set of boilers, where it is mixed with alkali of the strength of two to four de grees of the hydrometer, and boiled four hours, or until the alkali is spent.
The pulp and liquor are again forced up into the third washing tub, and all soluble matters washed out of it. Chlo ride of lime of the ordinary bleaching strength is now added, and agitation kept up for two hours longer; when steam is let on and the boiling continued until the salt is spent, when the whole is discharged into the fourth tub, where the spent chloride of lime is washed The pulp is now subjected to the opera tion of souring, whieh consists of sub mitting it to the action of acid and water of the usual strength used for bleaching, and keeping the whole in agitation for four hours. It is now ready to be dis
charged into a fifth tub or set of tubs, when the process is considered as com pleted.
The fine pulp, or stuff, as it is techni cally called, is transferred into a chest or large tub with a revolving agitator ; from thence into a vat, usually about 8 feet in diameter, and 21 feet in depth, and sus tained at a proper temperature by means of a fire ; and it is generally arranged for this vat to be placed against a wall of the room, that the fuel to the fire may be supplied at an aperture externally, to prevent any injury from smoke. During the whole of the subsequent process it is requisite that the pulp in the vat should be stirred up at short intervals, to keep it of an equal consistency. There are three workmen employed in this stage of the operation, called the dipper, the coveher, and the lifter. The dipper is provided with a mould, formed of well seasoned mahogany, across which par allel wires are stretched close together, a few other stronger ones being also placed at right angles with them, and at some distance from each other. The lines formed in the paper by these wires are called watermarks; hut, in the modern improvement of wove paper, these are avoided by using wire cloth woven in a loom, which, being tightly stretched over the frame, produces no water-mark. This mould is provided with another frame, called a deckle, which fits it exact ly, and forms a boundary line to the sheet of paper, which would otherwise have a rough and jagged edge. This contri vance, by supplying an edge to the mould, gives it the character of a sieve, which enables the dipper, after he has dipped the mould into the vat, and taken in a sufficient quantity of the pulp, and given it a gentle motion to equalize its thickness, to drain the water away ; he then removes the deckle, replaces it on another mould, and proceeds as before ; while the second workman, the toucher, removes the sheet of paper thus made on to a felt, being a piece of woollen cloth, and then returns the mould to the dipper, who, in the meantime, has been operating with another mould, and form ing another sheet : they thus exchange the moulds, the one dipping, and the other couching, until they dipping, com pleted six quires of paper, which is called a post. When this quantity is com pleted, the heap is conveyed to the vat press, and subjected to heavy pressure. These six quires remain in the vat press until the dipper and the toucher have perfected another post, when they are removed to give place to it ; and then the office of the third workman, the lifter, commences. He separates the sheets of paper from the felts, and forms them into a pile, which is again subjected to a second press, which detaches from them a great quantity of moisture. Here it remains until the workmen are pre pared to replace it with a similar quan tity, when it is taken to the drying rooms, and.. hung up on lines to dry. These lines are carefully covered with wax, both to prevent adhesion and con traction ; and the opening of the win dows should be strictly attended to, that the drying may not proceed too rapidly. This being accomplished, it is taken down, shaken, to make the dust fall out, and to separate the sheets from each other, and laid up in heaps ready to be sized. The size is prepared of a due consistence, twice filtered, and a portion of alum added. The workman dips a handful of the sheets, holding them open at the edges, that they may more equally imbibe the moisture, and after this pro cess they are again subjected to the press. They are afterwards dried, sorted, brought under repeated and excessive pressure, and, finally, made up into quires and reams.