PAPER-MAKING. 



409 



rriher substances, as straw, are used for the coarser 

 kinds. These materials, after being washed, are sub- 

 jected to the action of a rev olvirig cylinder, the surface 

 of which is furnished with a number of sharp teeth 

 or cutters, all so placed as to act against other cutters 

 fixed underneath the cylinder. The 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 be 

 carried too far, it injures the texture of the paper by 

 corroding and weakening the fibres. In that kind 

 of paper intended for lithographic printing, the rags 

 should not be bleached by chlorine at all ; the least 

 quantity of chlorine will materially injure it. The 

 pulp, composed of the fibrous particles mixed with 

 water, is tranferred to a large vat, and is ready to be 

 made into paper. 



Paper is made either by the hand or by machinery. 

 When it is made by the hand, the workman is pro- 

 vided with a mould, which is a square frame with a 

 fine wire bottom, resembling a sieve, of the size of 

 the intended sheet. He dips this mould, and lifts up 

 a portion of the thin pulp, and holds it in a horizontal 

 direction. The water runs out through the inter- 

 stices 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 or woollen cloths, and 

 afterwards alone. They are then sized, by dipping 

 them in a thin solution of gelatin, or glue, obtained 

 from the shreds or 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, se- 

 lected, and made into quires and reams. Hot-pressed 

 paper is rendered glossy by pressing it between hot 

 plates of polished metal. 



Paper is also manufactured by machinery, and one 

 of the most ingenious methods is that invented by 

 the Messrs Fourdrinier. The general principles upon 

 which paper-making machinery operates are not dif- 

 ficult of comprehension. The rags, after having 

 been cut by the machine formerly alluded to, and 

 soyked in water, are in a state of pulp placed in a 

 wooden trough, called the vat. This vat is placed 

 at one extremity of a long wooden frame, whicli 

 has a revolving cylinder at each of its ends. Over 

 these two cylinders, which both revolve in the same 

 direction, there is stretched an endless web of brass 

 wire cloth. The vat, at the one end of the frame, 

 has an opening or slit along its whole length, which 

 is intended to permit the pulp to flow down upon 

 the wire web below ; and in order to regulate the 

 proper quantity of pulp, that flows down from the 

 vnt to the web, the slit in the side of the vat 

 may be made larger or smaller by means of a regulat- 

 ing screw. The cylinders being in motion while the 

 pulp is flowing from the vat upon the web, and 

 continued sheet of pulp, will be laid upon the web, 

 which is in continual motion forward from the vat. 

 The web moves slowly forward, and the pulp is dis- 

 persed equally over its surface by the action of ec- 

 centrics keeping it in a tremulous motion. When 

 tlie web arrives at the cylinder, at the other end of 

 the frame, the sheet of puip is wiped off by a large 



revolving cylinder, covered with felt or flannel, from 

 which it advances through between a series of rol- 

 lers, and over three polished cylinders heated by 

 steam, the second being of a higher temperature than 

 the first, and the third than the second. From the 

 last steam cylinder the pulp is delivered dried, and 

 in the state of paper on to a reel, when it is cut into 

 sheets. 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 cylin- 

 der, being strained through the wire web, at the 

 same time depositing a coat of fibrous particles on 

 the outside of the cylinder, which constitutes paper. 

 The strained water flows off through the hollow axis 

 of the cylinder, and the pulp is wound from the part 

 of the cylinder above water, in a continued sheet, ii 

 would be totally inconsistent with the plan of this 

 work to enter into minute detail in describing the 

 machinery employed in paper manufacture, and 

 numerous plans, elevations, and sections would be 

 necessary to make the action of all the parts intelligi- 

 ble even to a practical mechanic. The account 

 we have given will be understood by the general 

 reader, and those who wish for minute details must 

 have recourse to the accounts given of the various 

 patents that have been taken out by the original 

 inventors, and those who have followed them in the 

 way of improvement. 



It may be remarked that a most important part of 

 the process must be performed on the material before 

 it comes to the machine, in order that the paper may 

 be of a good quality, and free from knots and other 

 irregularities of surface. After the rags have been 

 thoroughly cut, they are passed through a sieve in 

 the state of pulp, which sieve is of such a fineness as to 

 allow the pulp to pass through, while the coarser par- 

 ticles are retained. This process, which is equally es- 

 sential to the hand and to the machine paper-making, 

 has consequently received great attention from those 

 who have devoted themselves to this important 

 branch of manufacture, and several ingenious con- 

 trivances have been devised for the effective clearing 

 of the pulp. Mr Turner contrived a most ingenious 

 piece of apparatus for this purpose, in which he 

 caused the pulp to pass through a sieve of a given 

 fineness, varying with the quality of the paper to be 

 made, and assisting the passage of the pulp through 

 the sieve, by causing a partial vacuum to be formed 

 below it, Mr Dickinson and Mr Ibitson have also in- 

 vented ingenious and effective machines for the same 

 purpose. By peculiar contrivances, invented and 

 patented by Messrs Towgood and Smith, the paper 

 is sized before it leaves the machine, and also cut 

 into sheets by the apparatus of Fourdrinier, or that 

 of Mr Cowper. For the purpose of making very 

 thick drawing or copper-plate printing paper, or fine 

 bristol boards, a process called couching, is followed ; 

 this consists in uniting two or more sheets, and press- 

 ing them together, in order to form one thick sheet. 

 This is a tedious process, and adds considerably to the 

 cost of these papers. Mr Dickinson, to whose in- 

 genuity much is due for improvements in all the de- 

 partments of the paper-making machinery, has some 

 time since taken out a patent for making plate and 

 drawing papers, by the union of the two continuous 

 sheets of pulp in the machine. One web of pulp 

 moves from each end of the machine towards the 

 centre, where, both passing between rollers, become 

 united, and being taken up by a web of felt are pass- 

 ed over the drying rollers, and delivered in one thick 

 sheet upon the reel. Mr Cubb has lately invented a 

 method of fabricating a beautiful species of embossed 

 paper, coloured in the pulp, and adapted for paper 

 hangings or for decorating the walls of rooms ; and 



