The above is the process for the plain or white tablets. In making the tinted tablets, the following additional particulars are to be attended to. The rags are cleansed, washed, and beaten into half 'Mfg in the usual way; the water being drained oft; the pulp is put into a vat with a solution in water of acetate of alumine, or sulphate of iron, as a mordant or ground to fix the colour intended to be made ; the whole is well incorporated, and suffered to remain for half an hour or more, when the colouring tincture, previously prepared, is added; after which, the whole being returned to the engines, is beaten into fine pulp, and then wrought into fine tablets. The dyeing materials chiefly made use of by Mr. Steart, are, mangrove bark, quercitron bark, best blue Aleppo galls, sulphate of iron, and acetate of alumine. A due combination of these materials pro duce a great variety of drabs, greys, sand-colours, &c.
An apparatus and process for sizing paper in a more effectual manner than it had previously been done, was recently patented by Mr. Towgood, of Dart ford, in conjunction with Mr. L. Smith, of Paternoster-row, London. This invention consists in the application of pressure along with the size ; which is effected by depositing on the surface of a pair of pressure rollers, or on one of them, if the paper be required to be sized only on one side, a thin uniform film of size, which is pressed into the paper as itbetween the rollers. An endless felt is sometimes made to pass over Orthe rollers, and in that case the size will be forced through the felt to the paper. This sizing apparatus may be applied either separately, or in combination with a paper machine of any construction ; but the form and arrangement of the different applications will necessarily vary with the form of the machinery to which it is applied. The form represented in the following diagram will be sufficiently explanatory.
sb represent two pressure rollers, with pieces of endless felts c c e, and ddd passing around them, being sup ported and guided by a series of friction rollers e e e and fff ; g is a small trough with a perforated bottom for supplying the surface on the surface of the pressure roller a; and k is a similar trough for supplying size to the roller i, which transfers its supply to the other pressure roller b ; and jj are two scrapers for keeping clean the sur faces of the pressure rollers.
The cutting of paper into sheets of any required dimensions as ex actly and expeditiously as possible, ban object of great importance to the manufacturer ; and as the machine made paper is of considerable greater width than is required, it becomes to cut it lengthwise. The following is the patented method adopted bylrrompton, of Tamworth, in Lancashire, and Mr. Taylor, of Marsden, in Yorkshire, according to their enrolled specification, dated 1828. Fig. 1 is a side elevation of the machine; Fig. 2 a plan of the cutters. a is the roller upon which the paper (either in the moist state in which it is delivered from the felts when freshly made, or when dry,) is rolled ; b b and c c are two pairs of drawing rollers, which conduct the paper first between the circular cutters e e, and thence on to the roller d, where it is wound in its divided state. The
shaft upon which the upper cutter is fixed, is driven by any prime mover; and by means of endless bands and pulleys it imparts motion to the upper drawing rollers b and c; these two upper rollers turn the two lower, by means of cog wheels at the other extremities of their axes, which gear into each other; the upper cutter has in like manner a toothed wheel upon its axis, which tarns another toothed wheel upon the axis of the lower; none of these toothed wheels are brought into view in the drawing, to prevent confusion. By the revolutions of these parts of the apparatus, the paper, represented by a line g g, is drawn from a between the rollers b, is severed at e, and thence is carried by the rollers c on to d, by means of an endless band from the latter, as shown. In order to accommodate this movement to the increasing circumference of the roller d, occasioned by the paper accumulating upon it, the band pulley on d is a friction roller, which is set so as to allow of its slipping a little in its revo lutions. It should also be noticed, that the axis of the lower cutter is not quite parallel to the axis of the upper one, by which means the edges of the cutters facing the rollers a are brought into contact, whilst the other edges diverge, which causes the paper to be more freely delivered from the cutters. The great rapidity of this process of cutting is evident.
Another method of cutting paper of great merit was patented by Mr. Edward Newman Fourdrinier, paper maker, of Hanley, in Staffordshire. It consists of a series of receiving rollers placed one over the other. The several webs of paper to be cut pass over these, are then brought together, and passed over the collecting roller equally distant from the others; and thence, by the aid of an endless felt or blanket which passes about a series of guide rollers, they are conveyed under the main cylinder of the machine, and delivered to the cutter at the opposite side to which they entered. The cutter consists of a machine which acts on the principle of shears ; the lower blade being fixed, and the upper attached to an arm which vibrates upon a centre, and placed to meet the sta tionary blade at an appropriate angle, so as to produce the best clipping action. When a sufficient quantity of the paper has passed over the lower blade to constitute the length of a sheet, the upper blade begins to descend ; but pre vioualy to the blades coming into contact, a holder, consisting of a bar extend ing the whole width of the paper connected with the same vibrating arm, is made to press down and hold the paper firm on the lower blade, while the cutting is performed. During the operation of cutting, the main cylinder, as well as the guide rollers, remain stationary, while an actuating rod returns to bring another length of paper. This vibrating rod gives motion to a sector, which has on its upper side retched teeth, that are acted upon by the rod as it moves in the direction from right to left, but which remain stationary while the rod moves in the contrary direction. The sizes of the sheets cut by this machine are regulated by an expanding crank, which gives motion to the actuating rod, and through that means to the main cylinder, and other parts of the apparatus.