his book, in the library of Wolfenbuttle, are on this | trate all the modern improvements in detail. Linen paper. The manner of fabricating this paper is described by Mr. Lloyd in the Philosophical Transactions, No. 166. A certain quantity of the asbestos is pounded in a mortar of stone till it is reduced to a substance like cotton. All the parts of earth or stone remaining in the asbestos are then taken off by means of a fine sieve, and it is formed into sheets of paper by another cutters fixed underneath the cylinder. The ordinary paper-mill. Mixing it with water reduces it to pulp; only, as it is heavier than that from linen rags, it requires to be continually stirred when they are taking it up with the frames. The only excellence of this paper is that the writing disappears when it is cast into the fire. It must be observed, at the same time, that as it is of a slender consistency, and easily torn, it is more an object of curiosity than use. Paper made from rags is manufactured through the whole of Europe and America. This kind of paper was utterly unknown to the ancients. The libri lintei, mentioned by Livy, and by other Roman writers, is proved by Guilandin to have been written on pieces of linen cloth, or canvass prepared for that purpose. But it is not sufficient to know that paper made from linen is a modern invention; it is necessary to know by what nation, and at what period, it was actually discovered. Polydore Virgil, De Inventoribus Rerum, c. ii. c. viii., confesses his ignorance of these facts. Scaliger, without any kind of proof, ascribes it to the Germans; and Count Maffei to the Italians. Other writers give the honour of this invention to some Greek refugees at Basil, to whom the manner of making paper from cotton in their own country had suggested the idea. Du Halde is persuaded that Europe derived this invention from the Chinese, who, in several provinces, make paper from linen rags. But this invention was practised by the Europeans before they had any communication with China, and previous to the taking of Constantinople, at which time the Greek refugees were supposed to have retired to Basil. The precise time of this discovery in Europe is not exactly known. In 1762 M. Miermann offered a reward to the person who could procure the most ancient manuscript written on this kind of paper. The memoirs sent to him along with the manuscripts were published at the Hague in 1767, and proved that this kind of paper had been used in Europe previous to the year 1300. and cotton rags are the common material of which paper is now made; but hemp and some other fi brous substances are occasionally used for the coarser kinds. These materials, after being washed, are subjected to the action of a revolving cylinder, the surface of which is furnished with a number of sharp teeth or cutters, which are so placed as to act against rags are kept immersed in water, and continually exposed to the action of the cutters for a number of hours, till they are minutely divided, and reduced to a thin pulp. During this process, a quantity of chloride of lime is mixed with the rags, the effect of which is to bleach them, by discharging the colouring matter with which any part of them may be dyed or otherwise impregnated. Before the discovery of this mode of bleaching, it was necessary to assort the rags, and select only those which were white to constitute white paper. If, however, the bleaching process is carried too far, it injures the texture of the paper by corroding and weakening the fibres. The pulp, composed of the fibrous particles mixed with water, is transferred to a large vat, and is ready to be made into paper. In the hand paper, the workman is provided with a mould, which is a square frame with a fine wire bottom, resembling a sieve, of the size of the intended sheet. With this mould he dips up a portion of the thin pulp, and holds it in a horizontal direction. The water runs out through the interstices of the wires, and leaves a coating of fibrous particles, in the form of a sheet, upon the bottom of the mould. The sheets thus formed are subjected to pressure, first between felts of woollen cloths, and afterwards alone. The sheets are then sized, by dipping them in a thin solution of gelatin, or glue, obtained from the shreds and parings of animal skins. The use of the size is to increase the strength of the paper, and, by filling its interstices, to prevent the ink from spreading among the fibres by capillary attraction. In blotting paper, the usual sizing is omitted. The paper, after being dried, is pressed, examined, selected, and made into quires and reams. Paper is also manufactured by machinery, and one of the most ingenious methods is that invented by the Messrs. Fourdrinier, who may be considered as the Arkwrights' of paper making. In this arrangement, instead of moulds, the pulp is received in a continual stream upon the surface of an endless web, or brass wire, which extends round two revolving cylinders, and is kept in continual motion forwards, at the same time that it has a tremulous or vibrating motion. The pulp is thus made to form a long continued sheet, which is wiped off from the wire web by a revolving cylinder covered with flannel, and, after being compressed between two other cylinders, is finally wound into a coil, upon a reel prepared for the purpose. Another machine for making paper consists of a horizontal revolving cylinder of wire web, which is immersed in the vat to the depth of more than half its diameter. The water penetrates into this cylinder, being strained through the wire web, at the same time depositing a coat of fibrous particles on the outside of the cylinder, which constitute paper. The strained water flows off through the hollow axis of the cylinder, and the paper is We may now give a general outline of the pro-wound from the part of the cylinder above water, in gress of manufacturing paper, and afterwards illus-¦ a continued sheet. In 1782, the Abbé Andrez published a work entitled Dell' Origine, Progressi e Stato attuale d' Ogni Letteratura; in which he speaks of the discovery of many kinds of paper, and particularly of that made of rags. He states that paper made from silk was very anciently fabricated in China, and in the eastern parts of Asia; that the art of making this paper was carried from China to Persia about the year 652, and to Mecca in 706. The Arabs substituted cotton, the commodity of their own country, in place of silk, or rather bamboo. This paper of cotton was carried into Africa and Spain by the Arabs. The Spaniards, from the quantity of linen manufactured in the kingdom of Valencia, seem first to have adopted the idea of using linen rags; and the most ancient paper of this kind is of Valencia and Catalonia. The complete arrangement of a paper-machine similar to those employed in some of our largest manufactories may now be examined :— It is exihibited in our plate, PAPER-MAKING, fig. 1, in which a vat a is fed by a stream of pulp from a reservoir above. It should here be observed that this semi-fluid stuff, as it is technically called, would precipitate if it were allowed to remain in a quiescent state, to prevent which a species of stirrer is in continual operation. A wire frame or sifter, which is continually ascending and descending, serves to stop any large or injurious lumps from passing onward. From this the pulp passes to an endless web of wire-gauze b, which gradually advances onward, | carrying with it the semi-fluid mass. The pulp solidifies as it advances, and before it quits the wire plane it is pressed by a roller c covered by felt. It is now taken up by an endless web of felt, d, which is placed in an inclined direction, and then squeezed between two rollers, e, e. A second inclined plane of flannel conducts it to another pair of rollers. The paper continues its passage by the machinery, and is conducted over the polished surface of a cylinder, f, heated by steam, from which it passes to another, g, at a higher temperature. A third and still hotter cylinder, h, completes the process; and having been subjected to a slight degree of pressure from a woollen cloth it is wound on a reel, i. The ascending pipes, k, k, k, are intended to convey steam from a boiler in a separate building, and the exact degree of temperature is determined by a valve, which limits the supply of steam. The paper is cut into various lengths by an apparatus which will be described in a subsequent page, and thus, by a process unequalled for its simplicity and ingenuity, the liquid pulp introduced at one extremity of the machine may in the course of a few minutes be printed upon in the form of perfect paper at the other. mounted upon a central axle or spindle. The central figure of the above engraving represents a section taken vertically through the sieve, exhibiting the concentric rings as seen edgewise, bearing upon the radial arms. The rings are usually attached to the arms by small screws, but they may be fixed by soldering or in any other convenient way, and the whole is circumscribed by a hoop of thin metal, e c, which completes the sieve. The patentee sometimes makes a frame, consisting of radial arms with rings or hoops, either cast to the arms or affixed thereto concentrically, at about a quarter of an inch apart, and by solder or otherwise attaches to the upper level surfaces of the said frame of hoops a circular plate of metal, which is then placed in a lathe, and by a fine parting-tool cut through the apertures or narrow spaces forming the sieve. Under some circumstances, in place of the thin metal plate, or upper surface, the patentee constructs the face of the sieve of wire, by placing several rings of wire close to each other, side by side, on a level or plane, which wires are fastened together either by solder or by cross wires, and at distances of about half an inch apart. The circular concentric spaces as above described are left for the passage of the fine fibres of the pulp, and sometimes the sieves are constructed by affixing segment pieces to the frame or arms, as shown in the two side figures, the principal object of the patentee being the construction of a sieve capable of revolving, and that there should be interstices or long apertures in the sieve, corresponding, or nearly so, with the rotary wave in which the pulp flows through and under the sieve. The sieves are generally made from about twentyfour to thirty inches in diameter, and the upper surface of the rings forming the face of the sieve about half an inch in breadth, the outer ring or hoop being about eight inches deep. In order to facilitate the passage of the fine pulp and water, the sieves receive an up and down motion through the agency of a vibrating beam, the end of which is connected to a rod, the lower part of that rod being attached to a rapidly-revolving crank. We have now to examine a variety of processes for separating the knots and other extraneous matters in the passage of the pulp through the sieves prior to its manufacture into complete sheets of paper. Mr. Turner's improved process may first be noticed. These improvements enable the patentee to dispense with the common vat, in which the pulp for making paper is mixed with water and agitated, The effects of this rapid raising and depressing of immediately before it flows on to the wire-gauze or the sieves will be, that a partial vacuum will be proendless web, constructed upon the principle of Four-duced beneath each sieve as it rises, which will cause drinier's patent, or any other paper-making machine of a similar character: this sieve may also be applied with great advantage to the common vat used for hand papers. C These sieves are of a circular form, and composed of a number of concentric rings of metal, smoothly formed, with small openings between them, from about a 50th to 100th part of an inch apart. This series of rings are to be attached to radial arms, the air above to carry the fine fibres of the pulp through the interstices of the sieve, and in the descent of the sieves the pressure of the liquid will force upwards any lumps which might otherwise clog up the interstices of the sieves. The fine fibres of the pulp are kept in continual agitation, and prevented from subsiding, by a rotary motion of the sieves on their spindle, which supersedes the necessity of the hog employed in other paper-making machines. The coarse parts of the pulp, that is, the lumps and knots, being thus prevented from passing, are retained in the sieves, and may be removed from time to time as may be found necessary, while the finer parts of the pulp having passed through a sieve into a box below, it flows thence over a lip, on to the ordinary wire web of the machine, in the usual way, and is then made into paper. Another mode of separating the knots and lumps from the fine fibres of the pulp may now be described. It is the invention of Mr. Dickinson, and like the preceding it has also been made the subject of a patent. The accompanying figure represents a trans-link, and by these links it is hung to two levers, k, k, verse section of the apparatus. in such a way that the levers in moving up and down raise and depress the float, but in all cases without bringing any part of it into contact with the cylinder. It is intended, with the links and levers to which it is fixed, to be much heavier than water, so that after being elevated by the levers it may sink very suddenly by its own weight when they are no longer supported. The range of up and down movement given to this float should be about one inch and a quarter, and the rate of movement about eighty or 100 alterations per minute, and this by suddenly checking the flow of pulp through the apertures in its descent, or rather reversing the flow which in its ascent it promotes, prevents any lodgment of the fibres of rag. A shallow vat is shown at a, in which the revolving cylinder b works. The pulp, being diluted to the consistency which suits the paper-machine it is intended to supply, is delivered into this vat, and the The cylinder b has a toothed wheel y, fixed on the level of it is regulated by means of a waste, so as to tube part of one of the ends, and working between keep the vat nearly full. From this vat there is two metal flanches fixed to the wooden side of the no outlet for the pulp except through the peri-vat, for the purpose of keeping the pulp away from phery of the revolving cylinder b, and out of each end of it into the troughs c, c, through which it is conducted to the machine that is intended to make it into paper. the wheel, and it is made to revolve by a pinion fixed on a spindle, which goes across the vat and is fixed by two plummer blocks on the outside of the troughs, and has a rotary motion given to it The revolving cylinder b is constructed like a by a rigger, by means of strap a from any convesquirrel cage, of circular hoops, or an endless spiral nient power at the rate of forty or fifty revolutions wire attached to transverse metal bars, and is so per minute. This spindle has also fixed upon it formed that the spaces between the hoops, or be-two double eccentrics, immediately under the levers tween each spiral ring of the wire, are sufficient to k, k, so that in every revolution it twice lifts those allow of the passage of the fibres of pulp, but narrow | levers, and at the same time elevates the float d. enough to intercept the knots and other substances which it is desirable to keep out of the paper, and which, when the machine is at work, will therefore remain and accumulate in the vat a. For making fine papers it is found practicable to pass the pulp through spaces the hundred and fifteenth part of an inch wide, and even less than that; but the cylinder must in other cases be formed with wider apertures, as for coarser paper the fibres are larger, and in some cases they require to be twice the width above specified. It has been before mentioned that the pulp enters the revolving cylinder solely through the periphery, the ends being solid except the axis, which at each end consists of a large tube, through which the pulp flows out. The hoops of wire, of which the periphery is formed, are about three-eighths of an inch wide on the outer surface, and about one-fourth of an inch thick; and the inner surface about one-fourth of an inch wide, so that the apertures towards the inside of the cylinder are wider than they appear externally. The best mode of forming these cylinders is by a spiral wire drawn to the shape above described, and wound round and attached to the transverse bars by a rivet at every point of contact, and the ends of the transverse bars require to be firmly fixed to the cylinder ends by screws and soldering. The diameter of the cylinder b is not very material; fourteen inches has, however, been found the most convenient size; the length of this cylinder must be regulated according to the size of the machine it is intended to supply with pulp, but a cylinder four feet long in the grooved part will supply pulp to a machine of the largest size in ordinary use, and is capable of making paper four feet six inches wide: when of that breadth, it is necessary to have a wheel and pinion at each end. The metal flanches v, v, v, are firmly fixed to the sides of the vat a, with a water-tight joint, and form the bearings in which the cylinder works. Mr. Ibotson has also directed his attention to this branch of the art of paper-making. We have seen that when sieves or strainers made of wove wire are employed for separating the knots from the paper stuff they soon become stopped, and will not allow the pulp to pass through them; sieves of this kind are necessarily made of very fine wire, that is to say, there must be a great many wires or holes to the inch, and consequently the diameter of each individual wire must be a very small fraction of an inch. The principle of this invention is, that instead of making use of round wire, woven or otherwise, for the purpose of making a strainer, the inventor uses a number of bars of brass or copper, of about half an The pulp would naturally accumulate on the sur-inch in width, the upper side of each of which bars, face of this cylinder, and almost immediately stop up the aperture between the wires; but this effect is prevented by the agitation of the pulp in the interior of the cylinder, produced by the constant up and down motion of a float. This instrument is nearly long enough to reach from one end to the other of the cylinder inside. It is hollow, but made water-tight, and formed of strong copper, and has a metal bar, d, through it with an arm projecting from each end, to which is fixed a strong as also the edges, are made as nearly straight, flat, and smooth as possible, and a number of them are fixed side by side to the bottom of the sieve frame, so that the upper surfaces or the flat sides of all the bars may be in the same plane, that the edge of each bar may be parallel with the edge of the neighbouring bar, thereby leaving between every two bars a parallel slit of from about one-seventieth to about 100th part of an inch in width, less or more, according to the fineness or coarseness of the pulp to be strained. |