x^^^ ,0 c ''•'\v FHE MANUFACTURE OF PAPER R. W. SINDALL, F.C.S. CONSULTING CHEMIST TO THE WOOD PULP AND PAPER TRADES ; LECTURER ON PAPER-MAKING FOR THE HERTFORDSHIRE COUNTY COUNCIL, THE BUCKS COUNTY COUNCIL, THE PRINTING AND STATIONERY TRADES AT EXETER HALL, 1903-4, THE INSTITUTE OF PRINTERS ; TECHNICAL ADVISER TO THE GOVERNMENT OF INDIA, 1905 AUTHOR OF "paper TECHNOLOGY," " THE SAMPLING OF WOOD PULP " JOINT AUTHOR OF " THE C.B.S. UNITS, OR STANDARDS OF PAPER TESTING," "the APPLICATIONS OF WOOD PULP," ETC. WITH ILLUSTRATIONS, AND A BIBLIOGRAPHY OF WORKS RELATING TO CELLULOSE AND PAPER-MAKING ^2^-H*| NEW YORK D. VAN NOSTRAND COMPANY 23 MURRAY AND 27 WARREN STREETS ^ -n Oo^ Xj. g. TaxUt Board i>39f PREFACE Paper-making, in common with many other industries, is one in which both engineering and chemistry play important parts. Unfortunately the functions of the engineer and chemist are generally regard'ed' as independent of one another, so that the chemtst is only called in by the engineer when efforts along the lines of mechanical improvement have failed, and vice versa. It is impossible, however, to draw a hard and fast line, and the best results in the art of paper-making are only possible when the manufacturer appreciates the fact that the skill of both is essential to progress and commercial success. In the present elementary text-book it is only proposed to give an outline of the various stages of manufacture and to indicate some of the improvements made during recent years. The author begs to acknowledge his indebtedness to manufacturers and others who have given permission for the use of illustrations. CONTENTS PEEFACB LIST OF ILLUSTRATIONS CHAPTER I. HISTORICAL NOTICE II. CELLULOSE AND PAPER-MAKINa FIBRES . III. THE MANUFACTURE OF PAPER FROM RAGS IV. ESPARTO AND STRAW .... V. WOOD PULP, AND WOOD PULP PAPERS . ^ VI. BROWN PAPERS AND BOARDS . VII. SPECIAL KINDS OF PAPER VIII. CHEMICALS USED IN PAPER-MAKING IX. THE PROCESS OF " BEATING" . X. THE DYEING AND COLOURING OF PAPER PULP ,^^1. PAPER MILL MACHINERY XII. THE DETERIORATION OF PAPER Xin. BIBLIOGRAPHY INDEX 273 PAGE V ix 1 20 47 72 95 126 137 153 175 199 214 229 253 LIST OF ILLUSTRATIONS FIG. PAGE 1. SHEET OF PAPYRUS, SHOWING THE LAYERS CROSSING ONE ANOTHER . . 3 2. AN EARLY PAPER MILL (fROM " KULTURHISTORISCHEN BILDER- BUCH," A.D. 1564) 10 3. THE PAPER MILL OF ULMAN STROMER, A.D. 1390 (SUPPOSED TO BE THE OLDEST KNOWN DRAWING OF A PAPER MILL) . 12 4. THE FIRST PAPER MACHINE, A.D. 1802. PLAN AND ELEVATION 17 5. THE IMPROVED PAPER MACHINE OF A.D. 1810 ... 18 6. A RAG SORTING HOUSE 47 7. A RAG DUSTER .49 8. A RAG CUTTER 50 9. INTERIOR OF PAPER MILL FOR HAND-MADE PAPER (r. BATCHELOR & sons) 51 10. view of a rag boiler, showing connections ... 52 11. a breaking and washing engine 54 12. oettel and haas' apparatus for the manufacture of electrolytic bleach liquor 58 13. the " hollander " beating engine 59 14. the hand mould, showing frame and deckle ... 61 15. apparatus for sizing paper in continuous rolls . . 63 16. a supercalender 65 17. the first watermark in paper .67 18. COTTON .69 19. LINEN .70 20. an esparto duster 74 21. Sinclair's "vomiting" esparto boiler .... 75 22. a porion evaporator 76 23. SCOTT's multiple effect EVAPORATOR . . . .79 24. A PRESSE-PATE FOR ESPARTO PULP 85 25. ESPARTO PULP 88 26. A CYLINDRICAL DIGESTER FOR BOILING FIBRE ... 89 27. STRAW 93 P. b LIST OF ILLUSTEATIONS FIG. PAGE 28. A PAIR OF BARKERS FOR REMOVING BARK FROM LOGS OF WOOD 98 29. VIEW OF HORIZONTAL GRINDER (a), WITH SECTION (b) . . 99 30. A VERTICAL GRINDER FOR MAKING HOT GROUND MECHANICAL WOOD PULP 101 31. CENTRIFUGAL SCREEN FOR WOOD PULP . . . . . 102 32. SECTION OF CENTRIFUGAL SCREEN FOR WOOD PULP . . 103 33. WOOD PULP DIGESTER, PARTLY IN ELEVATION, PARTLY IN SECTION , 106 34. VIEW OF ORDINARY SULPHUR-BURNING OVENS . . . 108 35. SPRUCE WOOD PULP ........ 114 36. MECHANICAL WOOD PULP 115 37. THE SCREENS FOR REMOVING COARSE FIBRES FROM BEATEN PULP 118 38. THE PAPER MACHINE (WET END SHOWING WIRE) . . . 119 39. PAPER MACHINE SHOWING WIRE, PRESS ROLLS, AND DRYING CYLINDERS 123 40. SINGLE CYLINDER OR YANKEE MACHINE .... 130 41. SECTION OF WET PRESS, OR BOARD MACHINE . . . 131 42. DOUBLE CYLINDER BOARD MACHINE 133 43. APPARATUS FOR MAKING PARCHMENT PAPER .... 138 44. GENERAL ARRANGEMENT OF PLANT FOR MAKING " ART " PAPER 143 45. SECTIONAL ELEVATION OF " COATING " PLANT . . . 144 46. COTTON PULP BEATEN 8 HOURS ...... 179 47. COTTON PULP BEATEN 37 HOURS 180 48. PLAN AND SECTIONAL ELEVATION OF A " HOLLANDER " . . 185 49. BEATING ENGINE WITH FOUR BEATER ROLLS. . . . 186 50. UMPHERSTON BEATER 188 51. SECTION OF UMPHERSTON BEATING ENGINE .... 189 62. NUGENT's BEATING ENGINE WITH PADDLES FOR CIRCULATING THE PULP .......... 190 53. A " TOWER " BEATING ENGINE WITH CENTRIFUGAL PUMP FOR CIRCULATING PULP . 191 54. WORKING PARTS OF A MODERN REFINING ENGINE . . . 192 55. CONVENTIONAL DIAGRAM OF A WATER SOFTENING PLANT . 216 56. AN " ENCLOSED " STEAM ENGINE ...... 220 57. AN ELECTRICALLY DRIVEN PAPER MACHINE . . . . 222 58. DIAGRAM OF THE " EIBEL " PROCESS 223 THE MANUFACTURE OF PAPER CHAPTEK I HISTORICAL NOTICE History. — The art of paper-making is undoubtedly one of the most important industries of the present day. The study of its development from the early bygone ages when men were compelled to find some means for recording important events and transactions is both interesting and instructive, so that a short summary of the known facts relating to the history of paper may well serve as an intro- duction to an account of the manufacture and use of this indispensable article. Tradition. — The early races of mankind contented them- selves with keeping alive the memory of great achievements by means of tradition. Valiant deeds were further com- memorated by the planting of trees, the setting up of heaps of stones, and the erection of clumsy monuments. Stone Obelisks. — The possibility of obtaining greater accuracy by carving the rude hieroglyphics of men and animals, birds and plants, soon suggested itself as an obvious improvement ; and as early as b.c. 4000 the first p. B 2 THE MANUFACTUEE OF PAPEE records which conveyed any meaning to later ages were faithfully inscribed, and for the most part consigned to the care of the priests. Clay Tablets. — The ordinary transactions of daily life, the writings of literary and scientific men, and all that was worthy of note in the history of such nations as Chaldea and Assyria have come down to us also, inscribed on clay tablets, which were rendered durable by careful baking. On a tablet of clay, one of the earliest specimens of writing in existence, now preserved in the British Museum, is recorded a proposal of marriage, written about b.c. 1530, from one of the Pharaohs, asking for the hand of the daughter of a Babylonian king. Waxed Boards. — Bone, ivory, plates of metal, lead, gold, and brass, were freely used, and at an early period wooden boards covered with wax were devised by the Komans. In fact, any material having a soft impressionable surface was speedily adopted as a medium for the permanent expression of men's fancy, so that it is not strange to find instances of documents written on such curious substances as animal skins, hides, dried intestines, and leather. The works of Homer, preserved in one of the Egyptian libraries in the days of Ptolemseus Philadelphus, were said to have been written in letters of gold on the skins of serpents. Leaves, Bark. — The first actual advance in the direction of paper, as commonly understood, was made when the leaves and bark of trees were utilised. The latter especially came speedily into favour, and the extensive use of the inner bark {liber) made rapid headway. Manuscripts and documents written on this liber are to be found in many museums. Papyrus. — The discovery of the wonderful properties of the Egyptian papyrus was a great step in developing the art of paper-making. The date of this discovery is very uncertain, but one of the earliest references is to be found HISTORICAL NOTICE 3 in tlie works of Pliny, where mention is made of the writings of Numa, who lived about b.c. 670. This celebrated plant had long been noted for its value in the manufacture of Fig. 1.— Sheet of Papyrus, showiDg the layers crossing one another (Evans). mats, cordage, and wearing apparel, but its fame rests upon its utility in quite a different direction, namely, for convey- ing to posterity the written records of those early days which have proved a source of unending interest to antiquaries. B 2 4 THE MANUFACTURE OF PAPER The Egyptian papyrus was made from the fine layers of fibrous matter surrounding the parent stem. These layers were removed by means of a sharp tool, spread out on a board, moistened with some gummy water, and then covered with similar layers placed over them crosswise. The sheets so produced were pressed, dried, and polished with a piece of ivory or a smooth stone. Long rolls of papyrus were formed by pasting several sheets together to give what was termed a volumen. Roman Papyri. — The Komans improved the process of manufacture, and were able to produce a variety of papers, to which they gave different names, such as Charta hieratica (holy paper, used by priests), Charta Fanniana (a superior paper made by Fannius), Charta emporetica (shop or wrap- ping paper), Charta Saitica (after the city of Sais), etc. The papyrus must have been used in great quantities for this purpose, since recent explorations in Eastern countries have brought to light enormous finds of papyri in a wonderful state of preservation. In 1753, when the ruins of Hercu- laneum were unearthed, no less than 1,800 rolls were discovered. During the last ten years huge quantities have been brought to England. Parchment. — Parchment succeeded papyrus as an excel- lent writing material, being devised as a substitute for the latter by the inhabitants of Pergamus on account of the prohibited exportation of Egyptian papyrus. For many centuries parchment held a foremost place amongst the available materials serving the purpose of paper, and even to-day it is used for important legal documents. This parchment was made from the skins of sheep and goats, which were first steeped in lime pits, and then scraped. By the plentiful use of chalk and pumice stone the colour and surface of the parchment v>^ere greatly enhanced. Vellum, prepared in a similar manner from the skins of HISTOEICAL NOTICE 5 calves, was also extensively employed as a writing material, and was probably the first material used for binding books. Until comparatively recent times the term " parchment " comprehended vellum, but the latter substance is much superior to that manufactured from sheep and goat skins. Palmer. — The Chinese are now generally credited with the art of making paper of the kind most familiar to us, that is from fibrous material first reduced to the condition of pulp. Materials such as strips of bark, leaves, and papyrus cannot of course be included in a definition like this, which one writer has condensed into the phrase " Paper is an aqueous deposit of vegetable fibre." A.D. 105. — The earliest reference to the manufacture of paper is to be found in the Chinese Encyclopaedia, wherein it is stated that Ts'ai-Lun, a native of Kuei-yang, entered the service of the Emperor Ho-Ti in a.d. 75, and devoting his leisure hours to study, suggested the use of silk and ink as a substitute for the bamboo tablet aiid stylus. Sub- sequently he succeeded in making paper from bark, tow, old linen, and fish nets (a.d. 105). He was created marquis in A.D. 114 for his long years of service and his ability. A.D. 704. — It has been commonly asserted that raw cotton, or cotton wool, was first used by the Arabs at this date for the manufacture of paper, they having learnt the art from certain Chinese prisoners captured at the occupation of Samarkand by the Arabs. The complete conquest of Samarkand does not, however, seem to have taken place until a.d. 751, and there is little doubt that this date should be accepted for the introduction of the art of paper-making among the Arabs. Recent Researches. — Professors Wiesner and Karabacek have ascertained one or two most important and inter- esting facts concerning the actual manufacture of imrc rag paper. In 1877 a great quantity of ancient manuscripts 6 THE MANUFACTURE OF PAPEE was found at El-Faijum, in Egypt, comprising about 100,000 documents in ten languages, extending from b.c. 1400 to A.D. 1300, many of which were written on paper. The documents were closely examined in 1894 by these experts, at the request of the owner, the Archduke Kainer of Austria. Eesearches of a later date resulted in the discovery of some further interesting documents which appear to estabhsh with some degree of certainty the approximate date at which 2^ure rag paper, that is, paper made entirely from rag, was manufactured. Chinese documents dated a.d. 768 — 786, which have been reported upon by Dr. Hoernle, and others dated a.d. 781 — 782 — 787, reported upon by Dr. Stein as recently as 1901, appear to show what materials were used by the Chinese paper-makers in Western Turkestan. The manuscripts mentioned were dug out from the sand-buried site of Dandan Uilig, in Eastern Turkestan. Professor Wiesner found that all the papers of the Kainer collection were made of linen rag, with an occasional trace of cotton, probably added accidentally. The earliest dated paper was a letter a.d. 874, but two documents, which from other reasons could be identified as belonging to a.d. 792, proved that at the end of the eighth century the Arabs understood the art of making linen paper on network moulds, and further that they added starch for the purpose of sizing and loading the paper. Professor Karabacek advances some ingenious explana- tions as to the origin of the idea that raw cotton was first used for paper-making, and he suggests that the legend owes its origin to a misunderstanding of terms. In mediseval times pajDer was known as Charta homhycina, and sometimes as Charta Daniascena, the latter from its place of origin. Paper was also made in Bambyce, and a natural confusion HISTOEIOAL NOTICE 7 arose between the terms, since the word homhyx was used as a name for cotton, and the paper commonly in use suggested that material to the mind of the observer, and the name became corrupted to homhycina. The suggestions of Professor Karabacek, together with the microscopical investigations of Dr. Wiesner, appear to show that paper made entirely from raw cotton fibre was not known. Invention of Rag Paper. — Dr. Hoernle, in discussing this question, points out that, taking a.d. 751 as the date when the Arabs learnt the art of paper-making, and a.d. 792 as the date when paper made entirely of linen rag was pro- duced, the date of the invention of rag paper must lie between these two dates. The documents discovered in Eastern Turkestan and bearing the dates mentioned, which papers fill up the gap between the years a.d. 751 and A.D. 792, were found to contain certain raw fibres, such as China grass, mulberry, laurel, as the main constituents, and macerated flax and hemp rags as the minor con- stituents. The addition and substitution of rag evidently increased in course of time, and since the improvement thus effected soon became an obvious and established fact, the raw fibres were omitted. Hence the credit of the manufacture of pure rag paper would be given to the people of Samarkand, the date being between the years a.d. 760 and a.d. 792 ; and further the constitution of such paper has been shown by Dr. Wiesner to be linen, and not cotton, as commonly stated. These researches are of such interest that we quote Professor Hoernle's translation of the summary of the principal results of Dr. Wiesner 's examination of the Eastern Turkestani papers so recently discovered :— - " Taking into account the dates assigned to the papers on 8 THE MANUFACTURE OF PAPEE palaeographic grounds, the following conclusions may be drawn from the examination of their material : — ''(1) The oldest of the Eastern Turkestani papers, dating from the fourth and fifth centuries a.d., are made of a mixture of raw fibres of the bast of various dicotyledonous plants. From these fibres the half-stuff for the paper was made by means of a rude mechanical process. "(2) Similar papers, made of a mixture of raw fibres, are also found belonging to the fifth, sixth, and seventh centuries. But in this period there also occur papers which are made of a mixture of rudely pounded rags and of raw fibres extracted by maceration. " (3) In the same period papers make their appearance in which special methods are used to render them capable of being written on, viz., coating with gypsum and sizing with starch or with a gelatine extracted from lichen. " (4) In the seventh and eighth centuries both kinds of papers are of equal frequency, those made of the raw fibre of various dicotyledonous plants and those made of a mixture of rags and raw fibres. In this period the method of extract- ing the raw fibre is found to improve from a rude stamping to maceration ; but that of preparing the rags remains a rude stamping, and in the half-stuff thus produced from rags it is easy to distinguish the raw fibre from the crushed and broken fibre of the rags. " (5) The old Eastern Turkestani (Chinese) paper can be distinguished from the old Arab paper, not only by the raw fibres which accompany the rag fibres, but also by the far- reaching destruction of the latter. " (6) The previous researches of Professor Karabacek and the author had shown that the invention of rag paper was not made in Europe by Germans or Italians about the turn of the fourteenth century, but that the Arabs knew its preparation as early as the end of the eighth century. HISTOETCAL NOTICE " The present researches now further show that the beginnings of the preparation of rag paper can be traced to the Chinese in the fifth or fourth centuries, or even earlier. " The Chinese method of preparing rag paper never pro- gressed beyond its initial low stage. It was the Arabs who, having been initiated into the art by the Chinese, improved the method of preparing it, and carried it to that stage of perfection in which it was received from them by the civilised peoples of Europe in the mediaeval ages. " (7) The author has shown that the process of sizing the paper with starch in order to improve it was already known to the Arabs in the eighth century. In the fourteenth century the knowledge of it was lost, animal glue being substituted in the place of starch, till finally in the nine- teenth century, along with the introduction of paper machines, the old process was resuscitated. But the inven- tion of it was due to the Chinese. The oldest Eastern Turkestani paper which is sized with starch belongs to the eighth century. " (8) The Chinese were not only the inventors of felted paper and the imitators of rag paper — though in the pre- paration of the latter they made use of rags only as a _3irrogate by the side of raw fibres — but they must also be credited with being the forerunners of the modern method of preparing ' cellulose paper.' For their very ancient practice of extracting the fibre from the bark and other parts of plants by means of maceration is in principle identical with the modern method of extracting ' cellulose ' by means of certain chemical processes." Paper-making in Europe. — The introduction of the art into Europe seems to have taken place early in the eleventh centui-y, when the Moors manufactured paper at Toledo. The early authorities who have studied this subject express 10 THE MANUFACTUEE OF PAPEE Fig. 2.— An Early Paper Mill (from " Kulturhistorischeii Bilderbuch, A.D. loQi). HISTORICAL NOTICE 11 the opinion that the paper produced in Europe at this time was made from cotton rags and from raw cotton, but, in view of the recent researches into the composition of paper, it is difficult to say how this idea arose, unless we accept the explanation offered by Professor Karabacek. In standard encyclopaedias the following statements are made as to existing early documents printed on paper made in Europe: — A.D. 1075. Syriac manuscripts of early date in the British Museum. A.D. 1102. A document printed on cotton, being a deed of King Eoger of Sicily, now at Vienna. A.D. 1178. A treaty of peace between the Kings of Aragon and Spain, said to be printed on linen paper, preserved at Barcelona. A.D. 1223. The "Liber Plegierum," printed on rough cotton paper. One of the most interesting books on this subject is the " Historical Account of the Substances used to describe Events from the Earliest Date," by Matthias Koops, pub- lished in 1800. This writer appears to have obtained most of his information from German authorities. The industry of paper-making passed through Spain into Italy, France, and the Netherlands. In 1189 paper was being manufactured at Hainault, in France, and the industry rapidly spread all over the Continent. In 1390 Ulman Stromer established a mill at Nuremberg, in Ger- many, employing a great number of men, who were obliged to take an oath that they would not teach anyone the art of paper-making or make paper on their own account. In the sixteenth century the Dutch endeavoured to protect their industry by making the exportation of moulds for paper-making an offence punishable by death. 12 THE MANUFAOTUEE OF PAPER The bulk of the paper used in England was imported from France and Holland, and it was many years before the industry was established in England. This is not sur- FiG. 3.— The Paper Mill of Ulman Stromer, A.D. 1390 (supposed to be the oldest known drawing of a Paper Mill). prising in view of the protective and conservative policy of the Continental paper-makers. Paper-making in England. — The actual period at which the manufacture of paper was first started in England is somewhat uncertain. The first mention of any paper-maker is found in Wynkyn de Worde's " De Proprietatibus HISTOEICAL NOTICE 13 Kerum," printed by Caxton in 1495, the reference being as follows : — And John Tate the younger, joye mote he brok, Which late hathe in England, doo Make thj^s paper thynne, That now in our Euglyssh Thys booke is prj^nted inne. John Tate was the owner of a mill at Stevenage, Hertford- shire. In the household book of Henry VII. an entry for the year 1499 reads, " Geven in rewarde to Tate of the mylne, 6s. 8cZ." In 1588 a paper mill was erected by Sir John Spielman, a German, who obtained a licence from Queen Elizabeth " for the sole gathering for ten years of all rags, etc., necessary for the making of paper." This paper mill was eulogised by Thomas Churchyard in a long poem of forty- four stanzas, of which we quote two : — I prayse the man that first did paper make, The only thing that sets all virtues forth ; It shoes new bookes, and keeps old workes awake, Much more of price than all the world is worth : It witnesse bears of friendship, time, and troth, And is the tromp of vice and virtue both ; Without whose help no hap nor wealth is won, And by whose ayde great works and deedes are done. Six hundred men are set to worke by him That else might starve, or seeke abroad their bread, Who now live well, and goe full brave and trim, And who may boast they are with paper fed. Strange is that foode, yet stranger made the same, For greater help, I gesse, he cannot give Than by his help to make poore folk to live. The industry made but little progress for some time after Spielman's death, and up till 1670 the supplies of paper were obtained almost entirely from France. The first British patent for paper-making was granted to Charles 14 THE MANUFACTURE OF PAPER Hildeyard in 1665 for " the way and art of making blue paper used by sugar bakers and others." The trade received a great impetus on account of the presence of Huguenots who had fled to England from France in con- sequence of the revocation of the edict of Nantes in 1685. In 1695 a company was formed in Scotland for the "manufacture of white and printing paper." Improvements in the art were slow until 1760, when Whatman, whose name has since become famous in connec- tion with paper, commenced operations at Maidstone. Meantime the methods by which the rags were converted into paper were exceedingly slow and clumsy, so that the output of finished paper was very small. Some interesting details as to the early manufacture of paper in England are given by Mr. Ehys Jenkins, and from his account of " Early Attempts at Paper-making in England, 1495^1788," the following extracts have been made : — About 1496. First attempts at paper-making by John Tate at Hertford. 1496. Tate's paper used by Wynkyn de Worde in " De Proprietatibus Rerum/' 1557. A paper mill in existence at Fenditton, Cambridge. 1569. A mill at Bemmarton, Wilts. 1574. Mill erected at Osterley, Middlesex, by Sir Thomas Gresham. 1585. Richard Tottyl asked for sole right to make paper for thirty- one years, which was not granted. 1588. John Spilman erected a mill at Dartford, Kent. Granted a patent for sole manufacture of paper. 1588. Churchyard's poem on the "Paper Myll built near Darthford by Master Spilman." 1 612. Robert Heyricke's mill at Cannock Chase, Staffordshire. 1636. The three or four paper mills in the neighbourhood of Hounslow and Colnbrook temporarily shut down on account of the plague, the collection of rags having been forbidden. 1665. Patent granted to Charles Hildeyard for an invention, "the way and art of making blew paper used by sugar bakers and others." HISTOEICAL NOTICE 15 About IfiTo. Approximate date of erection of mills at Wolvercote, Oxford, where the Oxford India paper is now made. 1678. Mill at Byfleet, Surrev, mentioned by Evelyn in his diary. 1682. Bladen — A patent for an engine and process whereby rags are wrought into paper. 1684. Baysmaker — A patent for "the art and misterj^ of making paper in whole sheets." 1684. Jackson — A patent for "an engine, either for wind or water, which prepareth all materials whereof paper may be made." Evi- dently Jackson was acquainted with the "Hollander" beating engine. 1686. A charter granted to the "White Paper Makers' Company " for the sole right of making paper exceeding 4s. a ream in value. 1674. Annual importation of paper, presumably from France, stated to be 160,000 reams, of average value of os. (Somers). 1689. Trade with France prohibited by royal proclamation. 1696. Price of paper very high owing to scarcity, being lis. per ream. 1712. Duties levied on all kinds of paper, manufactured or imported. 1725. Monopoly of making paper for Bank of England notes granted to De Portal, of the Laverstoke mills, Hampshire. This paper is still made by the firm of Messrs. Portal. 1739. Galliott and Parry estimated that there were 600 paper mills in England, making 6,000 reams a day. The Commissioner of Excise reported only 278. 1739. James Whatman erected a mill at Boxley, Maidstone. 1758. Baskerville printed an edition of Virgil on so-called " woven " paper. Early Methods. — The most rapid development of the industry appears to have taken place in Holland. The rags used for paper-making were moistened with water and stored up in heaps until they fermented and became hot. By this means the dirt and non-fibrous matter was rendered partially soluble, so that on washing a suitable paper pulp was obtained. The washed rags were then placed in a stamping machine resembling an ordinary pestle and mortar. The mortars were constructed of stone and wood, and the stamps were kept in motion by levers which were 16 THE MANUFACTURE OF PAPER raised by projections fixed on the shaft of a water wheel. The operation of beating thus occupied a long period, but the paper produced was of great strength. The invention of the " Hollander," a simple yet inge- nious engine which is deservedly known by the name of the country in which it first originated, gave a tremendous impetus to the art of paper-making, as by its means the quantity of material which could be treated in twenty -four hours was greatly increased. Unfortunately the date of the invention of this important machine has not been definitely traced. The earliest mention of it seems to occur in Sturm's " Vollstandige Muhlen Baukunst," published in 1718. It was in extensive use at Saardam in 1697, so that the invention is at least some years previous to 1690. On this point Koops says: ''In Gelderland are a great many mills, but some so small that they are only able to make 400 reams of paper annually, and there are also water mills with stampers, like those in Germany. But in the province of Holland there are windmills, with cutting and grinding engines, which do more in two hours than the others do in twelve. In Saardam 1,000 persons are employed in paper-making." The First Fourdrinier Paper Machine. Up till the year 1799 paper was made entirely in sheets on a hand mould, but during the last few years of the eighteenth century a Frenchman, Nicholas Louis Eobert, manager for M. Didot, who owned a paper mill at Essones, had been experimenting for the purpose of making paper in the form of a continuous sheet, and eventually produced some of considerable length. The idea was taken to England by Didot's brother-in-law, Gamble, and introduced to the notice of Messrs. Fourdrinier, wholesale stationers, of London. HISTOEICAL NOTICE 17 The first machine was naturally a very crude affair. It consisted of an endless wire cloth stretched in a horizontal Fig. 4. — The First Paper Machine, a.d. 1802. Plan and Elevation. position on two rollers, one of which rotated freely in a bearing attached to the frame of the machine, the other being fitted in an adjustable bearing so that the wire could be tightened up when necessary. p, c 18 THE MANUFACTUEE OF PAPER The beaten pulp, contained in a vat placed below the wire, was thrown up in a continual stream upon the surface of the wire, and carried forward towards the squeezing rolls. A shaking motion was imparted to the travelUng wire so as to cause the fibres to felt properly. A great deal of the water fell through the meshes of the gauze, and further quantities were removed by means of the press rolls. The wet paper was then wound up on to a wooden roller, which was taken out as soon as sufficient paper had been made. The whole process was carried on under great difficulties, but substantial improvements were soon made by the EiG. 5. — The Improved Paper Machine of a.d. 1810. enterprising Fourdriniers, who commenced operations in Bermondsey, employing Mr. Bryan Donkin, then in the service of Messrs. Hall & Co., of Dartford, who had shown himself keenly interested in the machine. In 1803 the first " Fourdrinier," so called, was built at Bermondsey, and erected at Two Waters Mill in Herefordshire. In this machine the mixture of pulp and water was carried forward between two wires, and, after passing through the couch rolls, transferred to an endless felt. This arrangement proved to be faulty because the water did not escape freely enough from the wire, and a great deal of the paper was spoilt. HISTORICAL NOTICE 19 Donkin, however, hit upon a simple but effective device for curing this fault by altering the relative position of the two couch rolls. Instead of keeping the two rolls exactly in a vertical position one over the other, he placed them at a slight angle so that the upper one should bear gently on the web of paper carried by the wire before receiving the full pressure of the rolls, and thus remove a greater pro- portion of the water. In this way the paper was firmer and less liable to break when pressed between the couch rolls, an additional advantage being secured in the fact that the upper wire could be dispensed with. The various improvements effected resulted in a machine the details of which appear in the appended diagram, the device of the inclined couch rolls being fitted about 1810. The mixture of water and pulp flowed from a stuff chest into a small regulating box and on to the wire over a sloping board. The pulp at once formed into a wet sheet of paper, the water falling through the meshes of the wire, being caught in a bucket-shaped appliance, and conveyed back to the regulating box. The stream of pulp was confined upon the wire by means of a deckle. Further quantities of water were removed by the aid of a pair of squeezing rolls before the web passed through the couch- rolls, after which the paper was reeled up on a wooden spindle. From this date the success of the machine was assured, though the inventor and his colleagues were practically ruined, an experience only too common with the early pioneers of many great and useful industrial enterprises. In fact, the firm of Messrs. Donkin were the only people to profit from the invention, for they manufactured a number of machines, as stated in the report of the Jurors of the Exhibition of 1851, and from 1803 to 1851 no less than 190 Fourdriniers were set to work. c 2 CHAPTEE II CELLULOSE AND PAPER- MAKING FIBRES When plants such as flax, cotton, straw, hemp, and other varieties of the vegetable kingdom are digested with a solution of caustic soda, washed, and then bleached by means of chloride of lime, a fibrous mass is obtained more or less white in colour. This is the substance known to paper-makers as paper pulp, and the several modifications of it derived from different plants are generally known to chemists as cellulose. Although plants differ greatly in physical structure and general appearance, yet they all contain tissue which under suitable treatment yields a definite proportion of this fibrous substance. The preparation of a small quantity of cellulose from materials like straw, rope, hemp, the stringy bark of garden shrubs, wood, and bamboo can easily be accomplished without special appliances. Soft materials, such as straw and hemp, are cut up into short pieces, hard substances like wood and bamboo are thoroughly hammered out, in order to secure a fine subdivision of the mass. The fibre so pre- pared is then placed in a small iron saucepan, and covered with a solution made up of ten parts of caustic soda and 100 parts of water. The material is boiled gently for eight or ten hours, the water which is lost through evaporation of steam being replaced by fresh quantities of hot water at regular intervals. When the fibrous mass breaks up readily between the fingers, it is poured into a sieve, or on a piece CELLULOSE AND PAPER-MAKING FIBEES 21 of muslin stretched over a basin, and washed completely with hot water until clean and free from alkali. Hard pieces and portions which seem incompletely boiled are removed, and the residual fibres separated out. These fibres are placed in a weak, clear solution of ordinary bleaching powder, left for several hours, and subsequently thoroughly washed. This simple process will give a more or less white fibrous material. The purest form of cellulose is cotton. A very slight alkaline treatment, followed by bleaching, is sufficient to remove the non-fibrous constituents of the plant, and a large yield of cellulose is obtained. For this reason the cotton fibre ranks high as an almost ideal material for paper-making, possessing the quality of durability. Cellulose is an organic compound, containing carbon, hydrogen, and oxygen in the following proportions : — Carbon .... 44*2 Hydrogen .... 6'3 Oxygen . . . . 49 '5 100-0 Its composition is represented by the formula Ce Hio O5. The celluloses obtained from various plants are not identical either in physical structure and chemical constitu- tion, or as to their behaviour when employed for paper- making. In fact, the well-known differences between the raw materials used for paper-making, and also betwesn the numerous varieties of finished paper, are to be largely accounted for and explained by a careful study of the cellulose group, particularly \Aith reference to the microscopic characteristics and the chemical composition of the individual species. The only vegetable substance which may be regarded as 22 THE MANUFACTUEE OF PAPEE a simple cellulose is cotton, all others being compound celluloses of varying constitution, the nature of which cannot be appreciated without a considerable knowledge of chemistry. The classification of such plants, therefore, in a book of this description must be limited to certain dis- tinctions having some immediate practical bearing on the question of paper manufacture. Cotton. — Eegarded as the typical simple cellulose, contain- ing 91 per cent, of cellulose, and remarkable for its resistance to the action of caustic soda. Linen. — The cellulose isolated from flax by treatment with alkali or caustic soda cannot readily be distinguished from cotton cellulose by chemical analysis or reactions. The difference is almost entirely a physical one. Flax is a typical compound cellulose, to which has been given the name pecto-cellulose on account of certain pro- perties. Other well-known plants of this class are ramie, aloe, " sunn hemp," manila. Esparto. — The cellulose isolated from esparto differs in composition from cotton cellulose : — Carbon .... 41*0 Hydrogen . . . . 5*8 Oxygen .... 53-2 100-0 It is regarded as an oxycellulose, being readily oxidised by exposure to air at 100° C. Other oxycelluloses familiar to the paper-maker are straw, sugarcane, bamboo. Wood. — The difference between wood and the plants already mentioned is expressed by the term lignified fibre or ligno-cellulose. This term is used to indicate that the wood is a compound cellulose containing non-fibrous CELLULOSE AND PAPER-MAKING FIBEES 23 constituents, to which has been given the name lignone. Jute is another example of this class. These distinctions may be exemplified by reference to a simple experiment. If three papers, such as a pure rag tissue or a linen writing, an ordinary esparto printing, and a cheap newspajDer containing about 80 per cent, of mechanical wood, are heated for twenty-four hours in an oven at a temperature of 105*^ C, the first will undergo little, if any, change in colour, while the others will be appreciably discoloured, the mechanical wood pulp j)aper most of all. This change is due to the gradual oxidation of the con- stituents of the paper, the ligno-cellulose of the mechanical wood pulp being most readily affected by the high tempera- ture, and the pure cellulose of the rag paper being least altered. The process of oxidation, brought about rapidly under the conditions of the experiment described, takes place in papers of low quality exposed to air in the ordinary circumstances of daily use, but of course at an extremely slow rate. The deterioration of such paper is not, however, due to the simple oxidation of the cellulose compounds, because other factors have to be taken into account. The presence of impurities in the paper on the one hand, and of chemical vapours in the air on the other, hastens the decay of papers very considerably. Percentage of Cellulose in Fibrous Plants. — The value of a vegetable plant for paper-making is first determined by a close examination of the physical structure of the cellulose isolated by the ordinary methods of treatment. If the fibres are weak and short, the raw material is of little value, and it is at once condemned without further inves- tigation, but should the fibre prove suitable, then the question of the percentage of cellulose becomes important. 24 THE MANUFACTUEE OF PAPER There are several methods employed for estimating the amount of cellulose in plants. The process giving a maximum yield is known as the chlorination method, the details of which are as follows : — About ten grammes of the air-dried fibre is dried at 100° C. in a water oven for the determination of moisture. A second ten grammes of the air-dried fibre is boiled for thirty minutes with aweak solution of pure caustic soda (ten grammes of caustic soda in 1,000 cubic centimetres of water), small quantities of distilled water being added at frequent intervals to replace water lost by evaporation. The residue is then poured on to a piece of small wire gauze, washed thoroughly, and squeezed out. The moist mass of fibre is loosened and teased out, placed in a beaker, and submitted to the action of chlorine gas for an hour. The bright yellow mass is then washed with water and immersed in a solution of sodium sulphite (twenty grammes of sodium sulphite in 1,000 cc. of water). The mixture is slowly heated, and finally boiled for eight to ten minutes, with the addition of 10 cc. of caustic soda solution. The residue is washed, immersed in dilute sodium hypochlorite solution for ten minutes, again washed, first with water containing a little sulphurous acid and then with pure distilled water. It is finally dried and weighed. The second process for estimating cellulose is based upon the use of bromine and ammonia. About ten grammes of the air-dried fibre is placed in a well-stoppered wide-mouthed bottle with sufficient bromine water to cover it. As the reaction proceeds the red solution gradually decolourises, and further small additions of bromine are necessary. The mass is then washed, and boiled in a flask connected to a condenser with a strong solution of ammonia for about three to four hours. The fibrous residue is washed, again treated with bromine water in the cold, and subsequently CELLULOSE AND PAPEE-MAKING FlBEES ^5 boiled with ammonia. The alternative treatment with bromine and ammonia is repeated until a white fibrous mass is obtained. In practice the paper-maker is confined to two or three methods for the isolation of the fibres, viz., alkaline pro- cesses, which require the digestion of the material with caustic soda, lime, lime and carbonate of soda, chiefly applied to the boiling of rags, esparto, and similar pecto- celluloses ; acid processes, in which the material is digested with sulphurous acid and sulphites. The latter methods are at present almost exclusively used for the preparation of chemical wood pulp. Yields of Cellulose in the Paper Mill. — The object of the paper-maker is to obtain a maximum yield of cellulose residue at a minimum of cost. Usually the amount of actual bleached ^^aper pulp obtained in the mill is less than the percentage obtained by careful quantitative analysis, for reasons easily understood. In the first place, the raw material is digested for a stated period with a carefully measured quantity of caustic soda, for example, at a certain temperature. Now the conditions of boiling may be varied by altering one or more of these factors, the period of boiling, the strength of solution, or the steam pressure, and the paper-maker must exercise his judgment in fixing the exact relation between the varying factors so as to produce the best results. In the second place, the mechanical devices for washing the boiled pulp and for bleaching cause slight losses of fibre, which cannot be altogether avoided when operations are conducted on a large scale. Frequently, also, a greater yield of boiled material may involve a larger quantity of bleaching powder, so that it is evident the adjustment of practical conditions requires considerable technical skill and experience. 26 THE MANUFACTUEE OF PAPEE The percentage of cellulose in the vegetable plants employed more or less in the manufacture of paper is given in the following table : — Table showing Percentage of Cellulose in Fibrous Plants. Fibre. Cellulose, per cent. Cotton 91-0 Flax 82-0 Hemp 77-0 Eamie 76-0 Manila 64-0 Jute 64-0 Wood (pine) 57-0 Bagasse 50-0 Bamboo 48-0 Esparto 48 to 42 Straw 48 to 40 The Properties of Cellulose. — Cellulose is remarkably inert towards all ordinary solvents such as water, alcohol, turpentine, benzene, and similar reagents, a property which renders it extremely useful in many industries, with the result that the industrial applications of cellulose are numerous and exceedingly varied. Solubility. — Cellulose is dissolved when brought into con- tact with certain metallic salts, bat it behaves quite diffe- rently to ordinary organic compounds. Sugar, for example, is a crystalline body soluble in water, and can be recovered in a crystalline state by gradual evaporation of the water. Cellulose under suitable conditions can be dissolved, but it cannot be reproduced in structural form identical with the original substance. If cellulose is gently heated in a strong aqueous solution of zinc chloride, it gradually dissolves, a thick syrupy mass being obtained, which consists of a gelatinous solution of CELLULOSE AND PAPEE-MAKING FIBEES 27 cellulose. If the mixture is diluted with cold water, a pre- cipitate is produced consisting of cellulose hydrate intimately associated with oxide of zinc, which latter can he dissolved out hy means of hydrochloric acid. The resulting product is not, however, the original substance, but a hydrated cellulose, devoid of any crystalline structure. Cellulose is also soluble in ammoniacal solutions of cupric oxide, from which it can be precipitated by acids or by substances which act as dehydrating agents, e.g., alcohol. Hydrolysis. — An explanation of the behaviour of cellulose towards the solvents already mentioned, and towards acid and alkali, requires a reference to its chemical composition. The substance is a compound of carbon, hydrogen, and oxygen represented by the formula Ce Hio O5 being one of a class of organic compounds known as carbo- hydrates, so designated because the hydrogen and oxygen are present in the proportions which exist in water. Water = Hydrogen + Oxygen H2 + 0. The Hio O5 in the cellulose formula corresponds to 5 (H2 0). When cellulose is acted upon by acid, alkali, and certain metallic salts, it enters into combination with one or more proportions of water, forming cellulose hydrates of varying complexity. This change is usually termed hydrolysis. With mineral acids like sulphuric and hydrochloric acids, cellulose, if boiled in weak solutions, is converted into a non-fibrous brittle substance having the composition C12 H20 Oio 2 H2 to which the name hydra-cellulose has been given. Similar changes occur, but at a much slower rate, Avheii cellulose is 28 THE MANUPACTUEE OF PAPEE in contact with free acids at ordinary temperatures. For this reason it is important that paper, when finished, should not be contaminated with free acid. The nature and extent of the chemical change can be varied by altering the strength of the acid and the con- ditions of treatment. The manufacture of parchment paper is an example of the practical utility of the chemical reaction between cellulose and acid. A sheet of paper is dipped into a mixture of three parts of strong sulphuric acid and one part of water, when it becomes transparent. Left in the solution it dissolves, but if taken out and dipped into water in order to wash off the acid the reaction is stopped, and a tough semi-transparent piece of parchment is obtained. The cellulose is more or less hydrated, having the composition Cl2 H20 Oio H2 0, a substance having the name amyloid. Oxidation. — Cellulose is only oxidised to any appreciable extent by acid and alkali if treated under severe condi- tions. It is remarkable that the processes necessary for isolating paper pulp from plants when digested with these chemical reagents do not act upon or destroy the fibre, and this capacity for resisting oxidation has rendered cellu- lose extremely valuable to many of the most important industries. The resistant power of the cellulose is, however, broken down by the use of acid and alkali in concentrated form. Oxalic and acetic acids are obtained when cellulose is heated strongly at 250° C. with solid caustic soda. Oxy- cellulose, a white friable powder, is produced by means of strong mineral acids. Nitric acid at 100° C. attacks the fibre very readily and produces about 30 — 40 per cent, of the oxidised cellulose. CELLULOSE AND PAPER-MAKING FIBRES 29 Cellulose Derivatives. The great number of compounds and derivatives, i.e., substances obtained by chemical treatment, may be judged from the following list. The substances of commercial importance are suitably distinguished from those of merely scientific interest by the printing of the names in small capitals. Acetic Acid. — An important commercial product obtained by the destructive distillation of wood. The crude pyroligneous acid is first neutralised with chalk or lime, and the calcium acetate formed then distilled with sulphuric acid. Wood yields 5 to 10 per cent, of its weight of acetic acid according to the nature of the wood. Acetone. — A solvent for resins, gums, camphor, gun cotton, and other cellulose products. Prepared by distilling barium or calcium acetate in iron stills, the acetate being obtained from the crude acetic acid produced by the dry distillation of wood. Acid Cellulose.— (^eeHydrsil-CeWulose.) Adipo -Cellulose. — A distinct compound cellulose present in the complex cuticular tissue of plants, and separated easily by suitable solvents from the wax and oily constituents also present. Alkali Cellulose. — When cotton pulp is intimately mixed with strong caustic soda solution, this compound is formed. It is utilised in the manufacture of Viscose. Amyloid. — Strong sulphuric acid acts upon cellulose and converts it into a gelatinous semi-transparent substance to which the name amyloid has been given. (See Parchment Paper.) 30 THE MANIIFACTUEE OF PAPEE Ballistite. — A smokeless powder composed of nearly equal parts of nitro-glycerine and nitrated cellulose, with a small quantity of diphenylamine. Carbohydrate. — A large number of important commercial products, such as cellulose, sugars, starches, and gums, consist of the elements carbon, hydrogen, and oxygen, associated in varying proportions. The ratio of hydrogen to oxygen in these compounds is always 2 : 1 (H2 and 0). Cellulose CeHioOs. Sugar C6H12O6. Dextrin n {Cq Hio O5). To all these substances the term carbohydrate is applied. Celloxin (Tollens). — A substance having the stated com- position CsHeOe considered to be present in oxidised derivatives of cellulose. Celluloid. — This well-known material is made by incor- porating camphor with nitro-cellulose, a plastic ivory- like substance being produced. In practice the process is as follows : — Wood pulp or wood pulp paper is saturated with a mixture of sulphuric acid (five parts) and nitric acid (two parts), which produces nitrated cellulose. The product is washed, ground, and mixed with camphor, the mastication being effected by heavy iron rollers. The mass thickens and can be removed -» in the form of thick sheets. These sheets are submitted to great pressure between steam-heated plates. The cake obtained is cut into sheets of any desired thick- ness, seasoned by prolonged storage, and afterwards worked up into boxes, combs, brush-backs, and many other domestic articles of a useful and ornamental character. CELLULOSE AND PAPEE-MAKING FIBRES 31 Cellulose Acetate (Cross). — If cellulose is heated with acetic anhydride at 180° C, viscous solutions of the acetates are obtained. The process yielding a definite acetate of commercial value is based upon the following reaction : — 100 parts of cellulose prepared from the sulpho-carbonate are mixed with 120 parts of zinc acetate, heated and dried at 105° C. Acetic anhydride is added in small quantity, and 100 parts of acetyl chloride. At a temperature of 50° C. the mixture becomes liquid, and cellulose acetate is subsequently obtained as a white powder. The compound can be used in the place of cellulose nitrate, and, being non-explosive, may gradually replace the latter in many industrial applications. Cellulose-Benzoate. — When alkali cellulose is heated with benzoyl chloride and excess of caustic soda, this substance is obtained. Cellulose Hydrate. — The substances produced by the action of acid and alkali on cellulose under certain strictly defined conditions are bodies containing cellulose united with water to form hydrates. The industrial applications of cellulose based upon this reaction are described under the special headings. Cellulose Nitrate. — A considerable number of derivatives are obtained by bringing cellulose into contact with nitric acid. Variations in the strength of the acid, the tempera- ture of reaction, and the time of contact determine the nature of the product. The best known nitrates are : — Cellulose di-nitrate. Cellulose tri-nitrate and tetra-nitrate, present chiefly in pyroxyline. Cellulose penta-nitrate. Cellulose hexa-nitrate, the chief constituent of gun- cotton. 32 THE MANUFACTUEE OF PAPER Charcoal. — Not a cellulose derivative in the strict sense of the term, charcoal being a residue obtained in the dry . distillation of wood. Collodion. — A soluble nitrate of cellulose used in photo- graphy. (See Pyroxyline.) Cordite. — A smokeless powder consisting mainly of nitro- glycerine and gun-cotton mixed with acetone. The materials are thoroughly incorporated and the resultant paste formed into threads which are dyed and then cut up into suitable lengths for cartridges. Cuto-Cellulose. — Synonymous with adipo-cellulose. Dextron. — A compound prepared from the waste liquors of the bisulphite process used for the manufacture of wood pulp. Resembles dextrin in its physical properties. Dextrose. — A carbohydrate which can be obtained by the action of mineral acids on cellulose. Commercial dextrose, or glucose, is prepared by the conversion of starch with sulphuric acid. The starch is mixed with dilute acid at a fixed temperature, and the starch milk obtained poured gradually into a vessel containing dilute acid, which is maintained at boiling point. The conversion is complete and rapid. Explosives. — The production of the several cellulose nitrates has given rise to a great number of highly explosive substances. Blasting Gelatine. — A mixture of nitro -glycerine with cellulose nitrates. Amberite, Ballistite, Cordite, and other smokeless powders, consisting of nitro-glycerine and cellulose nitrates in about equal proportions. Sporting powders made by mixing nitro-cellulose with barium nitrate, camphor nitro-benzene, such as indurite, plastomenite, etc. Glucose. —(See Dextrose.) CELLCJLOSE AND PAPER-MAKING FIBRES 33 Gun-cotton. — An explosive prepared by the action of nitric acid on cotton. Selected cotton waste suitably opened up is immersed in a mixture of three parts of nitric acid by weight (1*50 sp. gr.) and one part of sulphuric acid by weight (1*85 sp. gr.) and submitted to a number of processes by which the nitration is properly effected so as to produce a nitro-cellulose of uniform composition. The material is washed, reduced to pulp, and moulded into various forms. Hemi-Cellidose. — The constituents of plant tissues are extremely varied in character. Many plants contain substances which resemble true cellulose, but differing from it in being easily converted by hydrolysis, and by the action of dilute acids, into carbohydrates. Plants which contain a large proportion of such constituents are termed hemi-celluloses. In some cases certain crystallisable sugars can be obtained by hydrolysis under suitable conditions. Hydral-Cellulose(B\imGke). — A compound of merely scientific interest, resulting from the treatment of cellulose with hydrogen peroxide. When acted upon by alkali it is decomposed into cellulose and acid cellulose, the latter a derivative of unstable composition. Hydro-Cellulose. — This product, a white, non-structureless, friable powder, is obtained by treating cellulose with hydrochloric or sulphuric acid of moderate strength. The substance itself has no commercial value, but the reaction is useful in separating cotton from animal fabrics. If a woollen cloth containing cotton is soaked in dilute sulphuric acid, washed, and dried at a gentle heat, the cotton is acted upon, and can be beaten out of the fabric, the wool resisting the acid treatment. Lignin. — The complex mixture of substances which is associated with cellulose in wood, jute, and other p. D 34 THE MANUFACTURE OF PAPER ligno-celluloses. The conversion of wood into chemical pulp effects the removal of this material more or less completely. The well-known " phloroglucine " test for mechanical wood in papers is based upon the presence of lignin in the wood. Ligno-Cellulose.— Wood, and jute are typical bodies con- sisting of cellulose and complex non-cellulose, gene- rally described as lignin, associated together in the plant tissue. The chemistry of the non-cellulose portion of wood is a matter still under investigation, its importance from a commercial point of view being obvious from the fact that the removal of the ligniji during the conversion of the wood into wood-cellulose results in a loss of 50 per cent, of the weight of wood. Lustra-Cellulose. — Synonymous with and suggested as a more appropriate name for the material usually described as artificial silk. Mercerised Cotton. — "When cotton is immersed in strong solutions of caustic soda a remarkable change sets in. The physical structure of the fibre is entirely altered from the long flattened tube having a large central canal to a shorter cylindrical tube in which the canal almost disappears. Hydration of the cellulose takes place, and these changes are taken advantage of in the production of mercerised cloth (so named from the discoverer of the reaction, Mercer). Cotton goods, particularly those made of long stapled cotton, when mercerised, exhibit a beautiful lustre, and some magnificent crepon effects are obtained by the process. Methoxyl. — A constituent of the complex compound known as ligno-cellulose, which is present in wood and similar fibres. The amount of methoxyl in lignified tissue can be accurately determined, and it has been suggested that the proportion of methoxyl found in a cheap CELLULOSE AND PAPER-MAKING FIBRES 35 printing paper could be used as a measure of mechanical wood pulp present. Muco-Cellulose. — This term is applied to certain compound celluloses present chiefly in mucilages, gums, and in seaweeds (Algge). The natural substances are all of commercial importance — Iceland moss, Carragheen, Algin, etc. Naphtha. — One of the products of the dry distillation of wood, usually described as wood-naphtha, or wood spirit. Nitko-Cellulose.— The treatment of cellulose with nitric acid gives a number of nitro-celluloses according to the conditions of the process. (See Cellulose Nitrates.) Oxalic Acid. — A substance of great commercial importance prepared by heating the sawdust of soft wood, such as pine, fir, and poplar, with strong solutions of mixed caustic soda and potash to dryness. The wood yields after six hours a greyish mass containing about 20 per cent, of the acid, which is separated out by water and then crystallised. It is used for bleaching, and as a discharge in calico printing and dyeing. Oxy-Cell'idose. — A white friable powder produced by treating cellulose with nitric acid at 100° C. The oxidation of cellulose is brought about by several reagents such as chromic acid, hypochlorites of lime and soda, chlorine, and permanganates. The extent to which cloth has been damaged by overbleaching may be determined by a simple test with methylene blue solution, which is readily absorbed by oxy-cellulose present in such fabrics. Parchment. — A tough paper prepared by the action of sulphuric acid on unsized paper. (See page 137.) Pectins. — (See Pecto-Cellulose.) D 2 36 THE MANUFACTUEE OF PAPER Pecto-Cellulose. — A generic term applied to many important fibrous materials, such as flax, straw, esparto, bamboo, phormium, ramie, &c., which on alkaUne treatment yield cellulose for paper-making, and a non-fibrous soluble residue of complex composition. These soluble derivatives are known as pectin (C32 H48 O32), pectic acid (C32 H44 O30), and metapectic acid (C32 H28 O36). Although the soluble constituents of the pecto-cellu- loses amount to 50 per cent, by weight in most cases, no process for the recovery of the product in a commercial form has yet been devised. (See descrip- tion of Soda recovery, page 78.) Pyroxyline. — A substance prepared by nitrating cotton. The cotton is immersed in a mixture of nitric and sulphuric acids of carefully regulated strength, and subsequently washed free of the acid. Three volumes of nitric acid (sp. gr. 1*429) are diluted with two volumes of water and nine volumes of strong sulphuric acid (sp. gr. 1*839) added. To the solution when cool the cotton is added in small quantities at a time. The resultant pyroxyline is soluble in a mixture of equal quantities of alcohol and ether, and in the soluble form is utilised as collodion for photography. Silk, Artificial. — A remarkable substance made from wood or cotton cellulose, closely resembling silk in appearance and physical properties. Nitrated cellulose is dissolved in a mixture of equal parts of alcohol and ether. The solution is forced through five capillary tubes under high pressure, and the filament so obtained solidifying at once is wound together with other similar filaments upon suitable bobbins. Various modifications of this general process are in use, such as the solidification of the solution into threads by CELLULOSE AND PAPER-MAKING FIBRES 37 passing it into water ; the application of solvents less inflammable than ether and alcohol ; the use of other forms of dissolved cellulose such as those prepared by means of zinc chloride, ammoniacal copper oxide, or acetic anhydride. In all cases the yarn or thread is submitted to further chemical treatment for the removal of nitric acid and to render the material non- explosive and less inflammable. The finished product is soft and supple, can be easily bleached and dyed, and is capable of acquiring a high lustre. Smokeless Powders. — (See Explosives.) Sulplio-Carhouate. — (See Viscose.) Sulphate Cellulose. — Chemical wood pulp prepared by the sulphate process. (See page 107.) Sulphite Cellulose. — Chemical wood pulp prepared by the sulphite process. (See page 107.) Viscose. — A soluble sulpho- carbonate of cellulose, prepared by treating cellulose with a 15 per cent, solution of caustic soda, and shaking the product with carbon bisulphide in a closed vessel. The mixture forms a yellowish mass soluble in water, giving a viscous solution which has some remarkable and valuable properties. This viscose, on standing, coagulates to a hard mass which can be turned and pohshed. If spread on glass and coagulated by heat, films are obtained from which the alkaline by-products can be washed out. These films are transparent, colourless, very tough and hard. Vulcanised Fibre. — Fibre or pulp treated with zinc chloride in acid solution, or otherwise, for the manufacture of hard boards. (See page 139.) Willesden Goods. — Paper, fibre, and textiles when treated 38 THE MANUPAOTUEE OF PAPEB with cuprammonium oxide are partially gelatinised on the surface and rendered waterproof. (See page 139.) Wood Spirit. — (See Naphtha.) Xylonite. — (See Celluloid.) . FiBKES FOR Paper-making. Although the vegetable world has been explored from time to time for new supplies of cellulose, and some plants have been found serviceable in certain directions, yet the number of fibres in actual use is very limited. The following table indicates the principal sources of the material required for paper-making : — Fibre. Source of the Fibre. Application of the Fibre. Linen Rags, textile waste. High class writings and print- Cotton . Eags, textile waste. ings. High class writings and print- Esparto . Natural grass. mgs. Writings and printings. Straw Straw from various cereals— wheat, bar- ley, oats, etc. Printings, box and card boards. Wood . Mechanically ground Cheap papers, boxboards. wood. middles, tickets and cards, writings and printings. jj Chemically prepared wood. Threads, waste from Writings and printings. Flax Wrappings, boards, cable spinning mills. papers. Hemp Spinning refuse, old Wrappings, boards, cable rope, sailcloth, etc. papers, strong writings. Jute Waste, old gunny bags. Wrappings, boxboard, cards. Bamboo . Natural stems. Writings and printings (not in Europe, and only limited quantities elsewhere). Ramie Bast fibres of the plant : Eareiy used, except in special textile refuse. cases. Bagasse . Sugar-cane refuse. Common papers (chiefly ex- perimental results). Manila Textile and rope refuse. Wrappings, cable papers. Hemp CELLULOSE AND PAPER-MAKLNG FIBRES 39 Exploiting New Fibres. — The exploitation of any new paper-making fibre requires attention to certain important details, which may be fairly considered in the following order : — (1) Supply. — The supply of material must be plentiful and obtainable in large quantities. Too often this question is entirely neglected by those who bring new fibres to the notice of paper-makers, probably because they do not realise that enormous quantities of material are necessary to supply even a very small section of the paper trade, the fact being that few plants yield more than half their weight of paper-making fibre. (2) Suitability. — The fibre should be properly examined as to its chemical and physical properties in a laboratory equipped with appliances for its conversion into bleached paper pulp on a small scale. The examination of the fibre would include tests as to the amount of pulp which can be obtained from one ton of raw material, the approximate cost of treatment, and details as to the value of the fibre for paper-making. (3) Cost of Raw Material. — If the supply of material seems to be sufficient, and the paper pulp obtained possesses suitable qualities, then it is necessary to get accurate infor- mation as to the cost of the fibre delivered to some given spot at or near the place of collection. The exploitation of any new fibre for paper-making pur- poses will involve a recognition of the fact that the raw material must be converted into pulp at or near the place where the material is most abundant. The only interesting exception to this is the case of esparto fibre, which is imported into England in large amount, but this is only possible because esparto possesses most valuable paper-making qualities, and is obtained in countries close to England, where large quantities are S . 40 THE MANUFACTURE OF PAPEE consumed. It is doubtful whether other fibres could be utilised in the same way. (4) The Cost of Manufacture at or near the place of collection requires to be carefully worked out, due con- sideration being given to the actual cost of chemicals on the spot, cost of labour, and the conditions under which the maintenance of machinery can be efficiently looked after. (5) Carriage and Freight Charges are the last, but by no means the least, items of importance. It is not too much to say that the whole success of the exploitation of new paper- making fibre hangs entirely upon this item, the majority of many fibres which have been brought to the notice of the trade being suitable, but impracticable, solely on account of these and similar commercial considerations. In the pages of the trade press for the last few years the following fibres have been noticed : — (1) Flax Pulp. — This material was to be obtained from flax straw. Attempts were made on a commercial scale to produce quantities of flax fibre, but so far the efforts made have not been very successful. (2) Ramie Fibre. — This material has been exploited over and over again, chiefly for textile trades, its application as a paper-making material being limited to small quantities used for special purposes such as bank notes. The fibre is too valuable, except for textile industries, and can only come into the paper trade as a waste material from such sources. (3) Tobacco Fibre has been before the trade for some years, the idea being to utilise tobacco stems and other tobacco waste for the manufacture of paper suitable for use as wrappers for cigars, cigarettes, and similar purposes. (4) Agave Fibre. — This name is given to a large and important genus of fibre-yielding plants found chiefly in Central America. It is also found in India, and in 1878 an CELLULOSE AND PAPEE-MAKING FIBEES 41 experiment was made for the manufacture of paper at a mill near Bombay, but this did not give any satisfactory results, probably on account of the primitive methods used in treatment. (5) Bagasse. — The waste material from sugar-cane has been looked upon for many years as a desirable fibre, much time and labour having been given to the utilisation of this material. In spite of these efforts bagasse still remains an almost useless and unworkable material. This is partly due to inferiority of the pulp and partly due to difficulties connected with its treatment. Probably cultivation of the plant for the sake of its fibre instead of the sugar might give better results. (6) Peat. — The attempts made to utilise peat for paper- making are probably fresh in the minds of those paper- makers interested in the production of wrappers and boxboards. The nature of peat, however, is such as to exclude the hope of making any useful article. The material has been exploited by companies in Austria, Ireland, and Canada on a fairly large scale, with but a limited amount of success. (7) Cotton-seed Hulls. — Many patents have been taken out for the chemical treatment of cotton-seed waste and having for their object the removal of the particles of seed hulls, so as to obtain a pure cotton pulp. The scheme sounds attractive, but there are so many conditions which have to be taken account of that the commercial success of any undertaking based on the use of cotton-seed hulls is very questionable. The fact is that the hulls have a market value quite apart from the possibility of their application to paper-making, and this initial cost would prevent paper-makers from buying the material owing to the large quantity necessary for the manufacture of one ton of pure pulp. 42 THE MANUFACTUEE OF PAPER (8) Apocynum. — This plant is said to be utilised to some extent by the Eussian Government in the manufacture of bank notes, the plant being cultivated at Poltava. This is an instance of the particular application of a fibrous material in limited quantities, a proposition which is always feasible in the case of special requirements. (9) Cornstalk. — This fibre has been chiefly exploited in America, experts having been attracted by the enormous quantities of cornstalk available in the several wheat- producing States. The manufacture of paper pulp from this material on a large scale has yet to be established. (10) Japanese Paper Fibres. — In Eastern countries a great number of fibrous plants are utilised in small quanti- ties for the manufacture of special papers. It is obvious that in these Eastern countries the employment of fibres which are not cultivated in large bulk is readily possible when the question of price obtained for the paper and the cost of production are considered. Of such fibres may be mentioned the Mitsumata and Kodzu, easy of cultivation and giving a good yield of material per acre of ground. The waxed papers used for stencils in duplicating work on the typewriter are made from these fibres. The paper Mul- berry is also a well-known fibre ; while a third species particularly valuable for thin papers is the Gampi. (11) Antaimoto Fibre. — The bark of this shrub is utilised in Madagascar in very small quantities for local purposes and possesses little interest for paper-makers. (12) Refuse Hempstalk. — The suggestion of the use of this material comes from Italy, the hempstalk having been experimented with at San Cesario Mill. This also is a fibre of a local interest only. The percentage of cellulose is very high, being over 50 per cent. (13) Papyrus. — The revival of this celebrated material is of comparatively recent date. It should be noted that the CELLULOSE AND PAPER-MAKING EIBEES 43 manufacture of papyrus as carried out by the Egyptians, by smoothing out layers of bark in order to utilise them as sheets of paper, and the present day proposals which involve the production of paper pulp from papyrus, are two entirely different propositions, and the success of the old Egyptian method cannot be referred to as any assurance of success for the production of paper from papyrus along modern lines. The exploitation of this fibre must follow the lines of modern research and commercial investigation, and its value, if any, could then be established. (14) Pousolsia, — This is a fibre of the same family as hemp and ramie. The value of this material is at present unknown, but the ultimate fibre appears to possess a most extraordinary length. Very little information is available at present as to its value for paper-making. (15) Bamboo. — This material has been before the paper trade for many years, having first been exploited seriously by Mr. Thomas Koutledge in 1875. Since that date a good deal of work has been done in connection with the fibre, but not until recently has the investigation been made of a sufficiently extensive character to enable paper-makers to form some conclusions as to the best methods of obtaining a reliable paper pulp. The researches of the writer in India go to prove that with any fibre it is necessary to take into account all the factors likely to affect the final cost of the paper pulp delivered to any given paper mill. The figures given in a report recently published, " The Manufacture of Paper and Paper Pulp in Burma," show the necessity of thorough investigation into all the points likely to affect the final results, viz., the price at which the paper pulp can be sold in England, assuming that the fibre in question is suitable for the manufacture of paper. Examination of Fibres. — The exact chemical analysis of 44 THE MANUFACTURE OP PAPER a new fibre is necessary in order to establish completely its value for textile and paper-making purposes, but the investigation of the suitability of the fibre for paper-making may be simplified by simple reduction of the raw material with caustic soda. The following process is sufficient for all practical purposes : — Condition of Sample. — A record should be made of the general appearance of the sample, its condition and the amount available for the investigation. Any information available as to the source of supply and the growth of the plant should also be noted. Preparation of Sample. — The material is cut up into small pieces. The most convenient appliance for this pur- pose is a mitre cutter as used by pictare-frame makers. If the sample is a piece of wood, sections one inch thick cut across the grain of the wood are most suitable, as they can be readily cut up into thin flakes by this machine. Moisture in Sample. — A small average sample should be dried at 100° C. for the determination of moisture. Treatment with Caustic Soda. — About two hundred grams of the raw material is closely packed into a small digester or autoclave and covered with a solution of caustic soda having a specific gravity of 1*050. A perforated lead disc should be j)laced above the sample in the digester to prevent any of it from floating above the level of the solution. The material should be digested for five or six hours at a pressure of 50 lbs. The conditions of treatment here given will need to be varied according to the nature of the fibre. Some materials can be readily converted into pulp with weaker liquor and at a lower pressure, while others will require prolonged treatment. These conditions must be varied according to judgment or according to the effects produced by the conditions already set out. Unhleached Pulp, — The contents of the digester are CELLULOSE AND PAPER-MAKING FIBRES 45 emptied out into an ordinary circular sieve provided with a fine copper wire bottom, having a mesh of about sixteen to the inch. The sieve is immersed in water and the con- tents partially washed with hot water. The partially washed material is squeezed out by hand and tied up in a strong cloth and then kneaded thoroughly by hand in a basin of water which is repeatedly renewed until the fibre is thoroughly washed. The process of kneading at the same time reduces the fibre to the condition of pulp. The water is carefully squeezed out of the pulp by hand, and the moist pulp is then divided into two equal parts, the first of which is made up into sheets of any convenient size, care being taken that none of the fibre is lost. These sheets are then dried in the air and preserved as samples of unbleached pulp, a record being made of the weight produced. Bleached Pulp. — The second portion of the moist pulp is mixed with a solution of bleach, the strength of which has been accurately determined by the usual methods. The amount of bleach added should be about 20 per cent, of the weight of air-dry fibre present in the moist sample of pulp. The pulp should be bleached at a temperature not exceeding 38° C, and when the colour has reached a maximum the amount of bleach remaining in solution is ascertained by titration with standard arsenic solution. In this way the amount of bleaching powder required to bleach the pulp is determined. The product is then made up into sheets of pulp which are dried by exposure to air and subsequently weighed. Yield of Pulp. — The percentage yield of finished pulp obtained from the raw material is determined from the figures arrived at in the experiment described, and the weight of raw material necessary to produce one ton of bleached pulp is readily calculated. Examination of Bleached Fibre. — The fibre should be 46 THE MANUFAOTUEE OF PAPEE carefully examined under the microscope and a record made of general microscopic features, especially with refer- ence to the length and diameter of the fibres, and the proportion of cellular matter present, if any. Sample of Paper. — It is only in the case of short-fibred material similar to esparto and straw that sheets of paper capable of giving comparative results as to strength can be made. The figures obtained with fibrous materials of this kind are only comparative, because it is possible in practice to make a much stronger sheet of paper when the material is beaten properly under normal conditions. A similar investigation should be made by submitting the fibre to treatment with bisulphite of lime, that is to say, if the fibre lends itself to such a process. A lead-lined digester is necessary, and the solution employed is bisulphite of lime prepared according to the directions given on page 160. The preparation of sulphite pulp requires more attention than the manufacture of soda pulp. It is most important that the digester should be absolutely tight in order to prevent the escape of any free sulphurous acid gas, and the contents of the digester must be heated slowly until the maximum pressure has been reached. CHAPTEK III THE IVIANUFACTURE OF PAPER FROM RAGS The word rag is used to designate a very wide range of raw material suitable for conversion into paper. In the Pig. 6. — A Eag Sorting House. case of high-class hand-made writing papers only the best qualities are employed, such as new linen and cotton 48 THE MANUFACTURE OF PAPEE cuttings from factories, or well- sorted rags of domestic origin. The usual classification adopted by merchants who supply the paper mills is somewhat as follows : — New white linen cuttings (from textile factories). New white cotton cuttings (from textile factories). Fine whites (domestic rags). Outshots (a quality between fines and seconds). Seconds (a grade inferior to fines). Thirds (inferior and dirty well-worn rags). Coloured prints (of all grades and colours). Fustians and canvas. Manila and hemp rope. Baggy, gunny, and jute. The total amount of rag used in England for paper- making is not known. The only figures available refer to rags imported; and these cannot be regarded as a measure of consumption, which could only be arrived at by first ascertaining the quantity of home rags used. The imports of rag at stated periods are given in the appended table : — Eags Imported into England. Weight (tons) Value 1872. 1882. 1892. 1902. 22,254 £373,035 21,200 £303,349 23,032 £214,065 18,692 £173,732 1905. 23,681 £224,232 Sorting and Cutting. — All rags on arrival at the mill are carefully sorted. This process is conducted entirely by women, who sort and cut up the rags at special tables provided with cutting knives curved in shape similar to a scythe. These are fixed at an angle in the centre of the table, with the back towards and in front of each work- woman. The top of the table is made of thick coarse wire THE MANUFACTURE OF PAPEE FROM RAGS 49 SO that some of the dh't and foreign impurities may fall through. All buttons, hooks and eyes, pins, leather, pieces of rubber, and other articles are carefully removed, while seams and hems are also opened out. The rags are cut into slips 3 — 5 inches long and then recut crosswise, and thrown into suitable baskets or receptacles standing round the Fig. 7. — A Rag Duster. table, by which means the sorting operation is effectually carried out. The care and attention given to the sorting is an important item in the manufacture of papers of uniform quality, and in the best mills the sorting is carried out to such an extent that twenty or twenty-five grades are obtained. Dusting. — The rags are next passed through a machine which removes dirt. This is a hollow cylindrical or conical p. F. 50 THE MANUFACTUEE OF PA PEE drum having an external covering of coarse wire cloth, which rotates inside a wooden box. The shaft is provided with projecting spikes, so that the rags are violently Fig. 8.— a Eag Cutter. agitated in their passage through the machine. The dirt and other impurities fall through the wire on to the floor of the room, while the clean rags are discharged from the lower end of the drum. The loss in weight varies according to the condition of the rags. With good materials the loss THE MANUFAOTUEE OF PAPER FROM RAGS 51 may only be 1 — 2 per cent., while with dirty common rags the loss during cleaning and dusting may amount to 10 per cent. Boiling. — The further purification of the rags is effected by a chemical treatment, viz^, boiling at a high temperature Fig. 9. — Interior of Paper Mill for Hand-made Paper (R. Batchelor & Sons). fatty. with alkaline substances, which process removes glutinous, and starchy matter from the material. For this purpose a spherical digester is used, generally 7 — 9 feet diameter, and capable of holding 2 — 2J tons of rag. The boiler or digester is filled with dusted rags, and the requisite amount of alkaline solution added. The man- hole is then closed, and steam admitted through the hollow E 2. 52 THE MANUFACTUEE OF PAPER trunnions until the pressure reaches 20 or 30 lbs., at which pressure the boiling is continued for three to six hours according to requirements, the digester rotating slowly the Fig. 10.— Yiew of a Eag Boiler, shcwiL^ c_li e ti i whole time in order that the rags may be evenly and thoroughly boiled. The liquor employed for boiling is a solution of caustic soda, carbonate of soda, or milk of lime. In the case of caustic soda the amount required varies from 5 to 10 per cent, of the weight of rag. Caustic soda is preferable to lime, because it acts upon the grease and other fatty THE MANUFACTUEE OP PAPER FEOM RAGS 53 matters, forming a soluble compound which is freely removed in the subsequent process of washing. Many paper-makers, however, use milk of lime, carefully strained through fine cloth, almost exclusively. Considerable expe- rience and skill are necessary in this operation in order to avoid injury to the fibre not only as regards its strength, but also its colour. Washing. — When the rags have been sufficiently boiled, the steam is turned off and the pressure allowed to fall. This can be effected quickly by blowing off from a valve fixed at the bottom of the boiler opposite to the manhole. The cover is removed from the boiler and the boiler slowdy rotated in order that the contents may be discharged into a tank placed below. The '' black liquor," as it is called, is then drained away from the rags, which are immediately subjected to a preliminary washing. The process of washing must be carried out in a thorough manner in order to remove all soluble compounds, which if left would cause an unnecessary waste of bleach in the subsequent stages of purification. There are many schemes employed for •washing, most of them being devised with the idea of using a minimum quantity of water. The most general practice, in the absence of special machinery, is the preliminary treatment in the tank below the digester, followed by a more complete washing process in a machine known as a breaking engine. This apparatus is a shallow oval-shaped vessel with circular ends, divided lengthwise by a partition called a mid-feather, which, however, does not extend the full length of the apparatus. In one of the two channels into which the vessel is thus divided a heavy roll is fitted, which is provided with a number of steel knives. On the floor of this channel there is fixed a " bed-plate," also provided with projecting knives which are parallel with the knives 54 THE MANUFACTUEE OF PAPER in the roll. The distance between the knives in the roll and those in the " bed-plate" may be altered as required by means of an adjusting screw. In the other channel of the breaking engine there is fitted a " drum-washer," which serves for the removal of the dirty water from the machine. This drum is divided into sections by means of partitions which reach from the centre to the circumference. The Fig. 11. — A Breaking and Washing Engine. surface of the " drum- washer " consists of a fine brass wire cloth supported by a coarser material placed underneath. The breaking engine is half filled with clean water, and the rags are thrown into the engine until it is suitably filled. The rotation of the heavy roll causes the mixture of rags and water to circulate round the vessel, the floor of which is so constructed that the pulp is drawn between the roll and " bed-plate " and discharged over the '' back-fall," which is that portion of the sloping floor behind the *' bed-plate." THE IklANUFACTUEE OF PAPER FROM RAGS 55 The '' drum-washer " rotates with its surface in contact with the mixture in the engine, so that the dirty water passes through the wire cloth and is caught in the curved sections or buckets inside the drum and discharged into a trough adjacent to the centre, and thereby conveyed away from the engine. Clean water is allowed to run into the vessel at one end while the dirty water is discharged by means of the ''drum- washer." At the same time the rags are broken up by means of the knives on the roll, so that when the rags are sufficiently washed, a process which usually occupies four hours, they are also partially disintegrated. Bleaching. — The clean disintegrated rag is next bleached by means of ordinary bleaching powder solution. Bleaching powder is a substance prepared by the action of chlorine gas on dry slaked lime, resulting in the formation of a com- pound which has the property of bleaching or '' whitening" vegetable matters. The clear solution obtained by treating the powder with water is utilised by the paper-maker for bleaching the rag pulp. Various methods are used for this purpose. Sometimes the requisite volume of clear bleach liquor is added to the pulp in the breaker, and the material kept in constant circulation until the operation has been completed. In other cases the broken pulp is transferred to a "potcher," which is a vessel similar in shape to the breaker, but merely provided with paddles for keeping the pulp in circulation, and bleached by the addition of chloride of lime solution. Another method frequently adopted is to discharge the pulp from the breaker, immediately after the addition of the bleach, into brick or cement tanks, allowing the bleaching action to proceed spontaneously without pro- longed agitation. In some instances the process is hastened by adding dilute sulphuric acid to the pulp after the bleach liquor has 56 THE MANUFACTUEE OF PAPER been run in, or by heating the mixture with steam. For high-class papers such devices as this are seldom resorted to, as experience shows that the colour of pulp bleached by drastic methods does not maintain a high standard. The pulp is then thoroughly washed in order to remove every trace of residual bleach, and also the soluble com- pounds which have been formed during the operation. Very large quantities of water, clear and free from suspended dirt, are necessary. In some mills any excess of bleach is neutralised by the use of an " antichlor " such as sodium hyposulphite, or sodium sulphite, but the best results are undoubtedly obtained when the quantity of chemicals used is kept at a minimum. If the pulp is bleached in a breaker or potcher, the wash- ing is effected by the aid of the drum-washer. With pulp treated in steeping tanks, fresh water is allowed to percolate or drain slowly through the mass. Electkolytic Bleaching. The substitution of a sodium hypochlorite solution for the ordinary calcium hypochlorite solution obtained from common bleaching powder has been the aim of specialists for many years. As early as 1851 a patent was taken out by Charles Watt for decomposing chlorides of the alkali metals and the formation of hypochlorites. It was not until 1886 that a practical method was devised for producing an electrolysed solution of salt, but in that year Hermite introduced a continuous process in which an electrolysed solution having a strength of three grammes chlorine per litre was passed continuously into the potcher. Many patents for the electrolysis of salt have been taken out during the last twenty years, of which the Bird- Hargreave process is in operation in England, the Ehodin process in America, the Siemens and Halske in Norway, ELECTEOLYTIC BTiEACHING and the Oettel and Haas apparatus in Germany. The figures relating to the latter apparatus may be mentioned as typical of the present condition of electrolytic bleaching. The apparatus consists of a narrow rectangular trough divided into a number of chambers through which a solution of brine flows at a constant and steady rate. The electric current is passed through the solution by suitable electrodes, the temperature being kept down by means of a cooling coil. The cost of producing the bleach liquor as given by the inventors of the apparatus from the results of actual working are shown in the following table : — Table giving Analysis of Cost por Phoducing Bleach Liquor. Capacity of tank . . . 750 litres = 166 gallons. Screngtib. or density of brine . I'o Beaume, or 2."3 Twaddell. 286 lbs. of common salt required for 166 gallons. Hours worked 2 4 6 8 10 12 Grammes of chlorine per litre produced 4-35 7-38 9-9 12-42 14-31 16-20 Temperature C. of brine during operation 20 21 20 21 20 20 Amperes of 110 volts 00 50 46 52 47 43 Power in h.p. hours 16 31 45 61 75 89 Cost of the h.p. at '22(1. per h.p. hour Hd. 6|rZ. lOd. Is. l^d. Is. 4id Is.l^d. Cost of salt ls"6d. Is. 6d. Is. 6c/. Is. 6d. Is. 6d. Is. 6d. Total cost Is. 9^d. 2s. Ofrf. 2s. 4d. 2s. l^d. 2s. lO^d. 3s. lie/. Total chlorine ob- tained in kilos. . 3-262 5'535 7-425 9-315 10-732 12-150 Cost of chlorine per kilo. . 6-6d. 4.^d. 3|d 3-4rZ. 3-2d. •3d. Salt used per kilo. chlorine 35 20 15 12 10 9 The above costs have been estimated on prices as follows : — Coal . . .10s. per ton. Salt . . .12s. per ton. After 12 hours the 166 gallons (750 litres) are converted into electro- lytic bleach liquor containing 26| lbs. of active chlorine (12-15 kilos.). 58 THE MANUFACTURE OF PAPER Beating. — Although the rags are reduced by the breaking engine to a condition of fibrous hnt, called " half-stuff," they are not fit for conversion into paper. They have to be beaten in special machinery until a complete separation of the single fibres has been effected, and this process is Fig. 12. — Oettel and Haas' Apparatus for the manufacture of Electrolytic Bleach Liquor. rightly regarded by many paper-makers as the most important stage of manufacture. The beating engine is similar in construction to the breaking engine, but there are certain essential differences in arrangement and manipulation. There is usually no drum-washer ; the roll contains a large number of knives which are fixed in clumps or sets of three round the circumference ; the lowering of the roll upon the bed-plate is carefully watched and controlled, and the desired effects BEATING 59 are only obtained by strict attention to the condition of the pulp during the whole process. The beater is first partially filled with water, and the drained half-stuff added gradually until the "furnish," a convenient term applied to the contents of the engine, has ?3f^^W i^'iG. 13.— The " Hollander" Beating Engine. the proper consistency, which varies according to the nature and quality of paper required. The mass is circulated steadily round the engine by the action of the beater roll, which is lowered from time to time until the distance between the knives on the roll and those on the bed-plate has been set to the desired adjustment. This lowering of the roll and its proper adjustment call for the greatest care. Influence of the Beating. — The importance of this opera- tion can easily be judged from one or two specific examples. 60 THE MANUFACTUEE OF PAPEE In the case of rag papers the two extremes of variation are represented by the ordinary blotting paper on the one hand and a hard strong writing paper known as a loan on the other. Now the great difference in these papers maybe traced to the careful selection of the rag and the treatment in the beater as the two primary causes of the final results. For blotting papers it is essential that the rags should be old and tender. In the beating operation subsequent to the usual boiling and bleaching processes the half-stuff is beaten quickly with sharp knives, the roll being lowered soon after the engine is filled, so that the beating is finished in about one to one and a half hours. For the strong writing paper new strong rags are selected. In the beating process the knives used are dull, the roll is lowered slowly and cautiously, and the beating goes on for eight to ten hours. The effect of such difference in treatment is easily seen by examination of the fibres of the papers under the micro- scope. In the first case the fibres appear short with clean cut ends, the shape little distorted, the structure well defined, bearing a strong resemblance to the unbeaten material. In the case of the well-beaten paper the ends of the individual fibres appear to be drawn or frayed out, the fibres do not possess the sharp well-defined outline characteristic of blotting paper; they are partly split up into fibrillse which lie together in a confused mass. In the blotting paper these effects are produced because the knives being sharp cut up the material quickly, and in the tvriting paper because the dull "tackle" tends to draw out the fibres and tear them up lengthwise. The practical result is a spongy, soft, and bulky blotting and a hard, strong, heavy writing paper. Of course the great difference between a blotting and a writing paper is BEATING Gl not all due to this one operation, but is obtained by a series of operations, of which one of the most important is, how- ever, the beating. Colouring the Paper. — The pulp is brought to any desired tint by the addition of mineral pigments or aniline dyes to the contents of the engine. The latter soluble dyes, however, are seldom used for high-class rag papers. Prussian blue, ultramarine, and smalts are chiefly used for this purpose, giving toned blue, azure, and blue laid papers. Making the Paper. — The beaten pulp, when duly prepared, is run from the engine into store tanks known as stuff chests, ready for the actual manufacture. The pulp pro- perly diluted with water is strained through special screens to remove any in- sufficiently beaten material and any impurities present, after which it is run off into the vat, a square-shaped vessel built of wood or stone. The apparatus used in forming the sheets is called a hand mould. The mould is a rectangular frame of mahogany upon which is stretched tightly a fine wire cloth, the surface of the latter being kept flat by a coarser wire cloth fixed underneath, supplemented by wedge-shaped pieces of wood. A second frame called the deckle fits on to the mould in such a manner as to form a shallow tray, the bottom of which is the fine wire cloth. The vatman takes up the mould with both hands and dips it into the vat full of pulp in a slanting position, draw- ing it through the stuff towards him in a peculiar manner and lifting it out from the vat with a definite quantity of Pig. 14.— The Hand Mould showing Frame and Deckle. 62 THE MANUPACTUEE OF PAPEE the mixture in the frame. As the water drains away from the pulp, through the wire cloth, he imparts a shaking motion to the mould in order to cause the fibres to " felt " properly, this felting or interlacing of the fibres being an essential feature in the manufacture of a good sheet of paper. When the water has drained away sufficiently from the pulp, the vatman removes the deckle from the mould and passes the latter over to the coucher, who takes the mould, reverses it, and presses the contents, which may now be described as a wet sheet of paper, down on to a damp piece of felt, by which means the paper is transferred to the felt. He returns the mould to the vatman, who meanwhile has made another sheet with a duplicate mould, and then, having laid a second felt upon the wet sheet of paper, he proceeds to transfer the next sheet of paper to the second felt. This process is continued until a pile is formed consisting of wet sheets of paper alternated with pieces of felt. The pile is at once submitted to great pressure in the hydraulic press, and the excess water slowly forced out, while at the same time the sheets are compressed and thus "closed up," as it is termed. When all the excess water has been removed as far as possible, the pile is taken away and the sheets of damp paper taken out, the felts being placed in one pile ready for further use, and the sheets of paper in a second ready for the next process. The papers are put back into the press without felts between the sheets and left for some time. In most cases the sheets are turned round or mixed in with the sheets of another pile, before pressing. In this way any unevenness or irregularity in the sheets is counteracted and a more uniform result obtained. When these changes are repeated several times the paper acquires an even texture and becomes firm and hard. Drying the Paper.~The sheets are hung up in the loft, SIZING 63 as the drying room is called, upon poles or ropes. The moisture gradually evaporates, and the paper is thus dried by exposure to air. In winter it is necessary to warm the air in the loft, as the air is then saturated with moisture. In lofts of limited capacity the air is heated in order to hasten the process, but the best paper is allowed to dry EiG. 15. — Apparatus for Sizing Paper in continuous Rolls. naturally, as by this means the shrinkage is gradual and a maximum strength is attained. Sizing the Paper. — The dried paper as it leaves the loft is termed Waterleaf because, being unsized, it readily absorbs water, and therefore before it can be used it must be sized. For this purpose it is dipped into a solution of gelatine, an operation described as tuh-sizing or animal- sizing, the former term being used on account of the tub in which the size is kept, and the latter on account of the fact that the gelatine is made from animal matter such as hides, cartilage, hoofs, and other refuse. Animal Size. — This is prepared from hide pieces, skins, 64 THE MANUFACTURE OF PAPER and the like by a simple process, which, however, requires a good deal of care in order to obtain the best results. The material is first thoroughly washed in plenty of clean water, and then heated with a definite quantity of water in a steam jacketed copper pan. The pieces slowly dissolve until a solution of gelatine is produced, and after the dirt and impurities have settled to the bottom of the pan the clear liquid is drawn off into store vessels. There are many details of a technical character to be attended to in the manufacture of good gelatine, and as the process is expen- sive, considerable attention is demanded at this stage in the completion of a sheet of paper. The dry sheets of paper are sized by the simple expedient of dipping, or by the passage of the paper through a long trough. In the first case the workman takes up a number of sheets and dips the bunch into a vat of size at the proper temperature, about 100° Fahrenheit. He then allows the surplus size to drain off, and the sheets are submitted to a slight pressure in order to remove the excess of gelatine that will not drain off. In the second case a different method is adopted in that the sheets of paper are carried by travelling felts through a bath of heated size, the excess gelatine being removed by the action of rubber or wooden rollers through which the papers are passed before leaving the apparatus. The papers are quickly and evenly sized by this method, which is now most generally used. Glazing. — When the sheets of paper are quite dry they are read^^ for glazing, a process which turns the dull rough surface of the sized sheet into a highly polished smooth surface fit for use. The sheets are placed singly between copper or zinc plates, and a pile of these passed several times through heavy iron rollers, great pressure being applied to the latter during the operation. SIZING 65 *i 1 1 1 II ^Ei^ Ilk R^'-^^^b^^^Hl__J^^^"* ^■^'^ ii r Fig. 16. — A Supercalender. P. 66 THE MANUFACTUEE OF PAPER The amount of polish imparted by this plate-glazing pro- cess, as it is termed, can be varied considerably. With a light pressure and few rollings, the sheet of paper can be turned out having a fairly smooth surface, and without a conspicuously shiny appearance. By employing a great pressure and repeated rolling a much higher surface is attainable. If the plates are hot a still higher finish is possible. Machine-made rag papers are glazed usually by means of the supercalender, which is a stack of alternate steel and paper rolls placed one above the other in a vertical position. The reel of paper passes between these rolls and becomes highly surfaced. This operation effects many changes in the paper, besides imparting a good finish. The thickness of the sheet is reduced by about 40 per cent., the fibres being compressed much closer together. The tensile strength of the paper is also materially increased, and in every way the paper is improved. Moderation is essential in this as in everything, because excess of glazing weakens a paper, rendering it brittle and liable to crack when folded. Laid and Wove Papers. — When certain papers are held up to the light and carefully examined it will be noticed that they appear to contain delicate transparent lines running parallel with one another at equal distances of about an inch, and that these are intersected by similar transparent lines running at right angles, which are much closer together. Such papers are known as Laid Papers, and the peculiar formation of the transparent lines is due to the construction of the mould used in the making. The wire surface of this mould consists of a number of some- what stout wires placed about one inch apart, interwoven with finer wires running across and at right angles, which are threaded much closer together. When the mould is dipped into the vat and withdrawn, the water drains away WATEEMAEKS 67 from the under surface of the wire, and the moist pulp settles down on the upper surface ; but since the coarser wires project a little from the finer threads, the paper is slightly thinner along those wires, though to an almost infinitesimal extent, with the result that on drying the sheet appears to contain transparent lines. Wove papers are so called from the nature of the mould used. The surface of the mould in this case consists of fine wires equally distributed, being woven in such a manner that the wires are equidistant from one another, as in ordinary wire gauze. A wove paper, on being examined in the light, simply shows a number of small diamond- shaped spaces, which in the majority of instances are difficult to detect. The Watermark. — The transparent device observed in many papers when held up to the light is known as the watermark, a term pro- bably derived from the conditions existing at the time the sheet of paper is made on the mould. The effect is produced by means of a raised design sewn or soldered to the surface of the mould, the design being fashioned out of fine wire. When a mould thus fitted with the design is dipped into a vat of pulp and lifted out, the water falls through the wire, and the pulp sinks down on to the surface of the mould, forming a replica, so to speak, of the design, which is easily seen when the dry paper is held up to the light, because the paper is thinner just at those points where the wires forming the design come into contact with the wet pulp. Some of the watermarks are very elaborate and interesting. A familiar illustration of a beautiful design of this F 2 Fig. 17.— The First Water- mark in Paper. 68 THE MANCJFACTUEE OP PAPEE description is to be found in the Bank of England notes. As a general rule the ordinary watermark consists of a mere trade term such as "Vellum," '' Zenobia," or of the name of the manufacturer, such as *' J. Whatman," '*E. Batchelor," and so on. In the earlier days of paper- making many highly interesting designs were used, and some of these are still extant. In fact many of the names by which certain standard sizes of paper are known owe their origin to the watermarks employed. The earliest known watermark bears the date a.d. 1301, being in the form of a globe and cross, as shown. Of equal interest are those designs from which certain papers are called foolscap, crown, pott, post, royal, columbier, and so on. The watermarks are now little used, but the terms are still retained, as indicating the size of the sheet. Microscopic Features of Cotton and Linen Fibres. The cotton fibre is about 30 mm. long, with an average diameter of '025 mm. of tube-like shape, and having a prominent central canal. There are no cross markings on the cell walls, and the ends of the fibre are rounded off into a somewhat blunt point. It exhibits a marked tendency to twist itself, especially if dry, and this peculiarity is readily observed with the raw material. The process of paper-making alters the characteristic structure of the fibre very greatly. The ends of the fibre are seldom to be seen ; the curious twist is less prominent, and the fibres are torn and destroyed. The effect of the beating process, for example, on cotton is easily to be noticed by comparing the fibres of a blotting paper under the microscope with the fibres of a bank or lomi paper. The distortions produced by prolonged beating renders ( COTTON AND LINEN FIBKES 69 the determination of the exact percentage of cotton in a rag paper rather difficult, but the features to be looked for are the absence of pores, cross markings, the existence of a central canal, striations produced in many cases on the cell Fig. 18.— Cotton. walls parallel to the length of the fibre. The structural features are more readily observed when the fibres are stained with a suitable reagent. (See page 71.) The linen fibre has an average length of 27 mm. with a diameter of '02 mm. The raw flax is very different from raw 70 THE MANUFACTURE OF PAPER cotton and is easily distinguished. The fibre is slender in shape, having thickened knots at regular intervals through- out its length, the general appearance of which may be Fig. 19.— Linen. compared to a stick of bamboo. The central canal of the fibre is extremely narrow, running like a small thread through the length of the fibre. The cell walls are further marked by numerous pores, which appear as small dark lines running from side to side, but not meeting in the centre. COTTON AND LINEN FIBEES 71 In the treatment necessary for making paper these characteristics are largely destroyed, and while it is quite easy to ascertain that a paper is of linen, or of cotton, or that a paper is mainly cotton with a small percentage of linen, yet there are conditions under which it is difficult to determine the exact percentage of cotton or linen in a rag paper. If, for example, a paper contains nearly equal quantities of cotton and linen, the exact proportions can- not be determined closer than 10 per cent., especially in well-beaten papers. Reagent for Staining Fibees. Preparation. — Dissolve 2*1 grams potassium iodide and 0*1 grams iodine in 5 c.c. of water. Mix this solution with a solution containing 20 grams of dry zinc chloride in 10 c.c. of water. Allow the mixture to stand ; pour off the clear liquid into suitable bottles. Coloration Produced. Cotton, linen, hemp. — Wine red. Esparto, straw and wood cellulose. — Bluish violet. Mechanical wood, unbleached jute. — Yellow. Manila hemp. — Blue, bluish grey to yellow. CHAPTEE IV esparto and straw Esparto Papers. The value of Esparto for the manufacture of high-class printing and medium quality writing paper is well known. This material has qualities which cannot readily be obtained from other fibres, such as rag and wood pulp. It is chiefly used in papers required for lithographic printing, books, and art illustration, since it gives a sheet having a good surface and one which is soft and flexible. The grass is obtained from Spain, Morocco, Algeria, Tunis, and Tripoli, in which countries it grows wild, requiring very little cultivation. The condition of the crop is improved by proper treatment, and in districts where the grass is cut for export as a paper-making material attention is given to cultivation. The plant grows to a height of three or four feet, and when mature the long blades of grass curl up into the form of a cylinder resembling a piece of wire. The leaf consists of two parts, the stalk and a sheath, which are easily separated when harvested. The grass is pulled up by hand and stacked into heaps in order that it may be dried by the heat of the sun, after which process it is carefully picked over for the removal of all extraneous matter and impurities. It is then graded, the best sorts being kept for weaving, and the remainder being sold for paper-making. It is packed up into large bales of about 4 cwt. capacity, compressed into small bulk by powerful presses, and shipped to England. ESPAETO AND STEAW 73 Esparto Pulp. — The first process in the manufacture of the paper is cleaning. The bundles of grass are opened up, shaken out, and put through a willowing machine. This consists of a hollow conical drum, the outer surface of which is a coarse wire cloth. Inside the drum is fitted a shaft provided with wooden teeth, and as the grass passes through it is tossed about and the dust removed. The clean grass is conveyed by travelling belts to the digester house. For the production of a high-class paper the grass is often examined by girls, who stand on either side of the travelling conveyer and take out any coarse root ends and foreign material not removed by the willowing machine. Boiling. — The object of submitting esparto to chemical treatment is to obtain a pure paper-making fibre known as cellulose. The composition of this raw material is shown by the following analysis : — Spanish Esparto. Cellulose .... . 48-25 Water . 9-38 Aqueous extract . 10-19 Pectous matter . 26-39 Fatty matter .... 2-07 Ash 3-72 100-0 Yield of dry cellulose obtained in actual practice from good raw material . . . . 45 to 48 % By boiling the esparto with caustic soda under pressure for a stated time, the non-fibrous constituents are removed, leaving the cellulose in a more or less pure form according to the severity of the chemical treatment. 74 THE MANUFACTURE OF PAPER In practice the grass is packed tightly into upright stationary digesters and a definite quantity of caustic soda solution added, the amount of chemical used being equal to 15 — 18 per cent, of the weight of grass packed into the digester. The form of digester almost universally employed is that known as the Sinclair's '' vomiting " boiler, which is constructed so that a continuous circulation of the Fig. 20. — An Esparto Duster. liquid is maintained by means of what are called " vomit " pipes. These are fitted to the sides of the digester in such a manner that the caustic soda solution circulates from the bottom of the digester, up through the "vomit" pipes, and is discharged downwards upon the contents of the boiler through a perforated plate fixed in the upper part of the digester. The requisite quantity of caustic soda solution is placed in the digester, and steam admitted into ESPARTO AND STRAW 75 the bottom of the vessel while the grass is being thrown in. In this way a much larger weight of grass can be boiled at Fig. 21. — Sinclair's " Yomiting " Esparto Boiler. one operation, since the bulk is greatly reduced when the grass has become thoroughly soft and wet. When the boiler is loaded the inlet is closed up and steam 76 THE MANrFACTUEE OF PAPER turned on to the full pressure of about 40 or 50 lbs., this being maintained for a period of about four hours. The non- fibrous constituents of the esparto are gradually dissolved out by the caustic soda, and when the operation is com- pleted the black liquor is run off from the digester into large store tanks, and the esparto grass which remains in D D >'>Hinn)H»»ji»i,n>,>,n ,,,,„n kMfff'fknirn vt",iiifi' -III,,. Mt,^-S777r\ V>»»^M^^./^i.,. w e V ^ ^ 9 3 ^ Fig. 22. — A Porion Evaporator. the digester is then completely washed until the soda is almost entirely washed out. The conditions for boiling and bleaching esparto are varied by the paper-maker as circumstances require. A maximum yield of fibre is obtained when the least possible quantity of caustic soda is used, but a larger percentage of bleaching powder may be necessary to ensure a well bleached pulp. The use of an excess of caustic soda is ESPARTO AND STRAW 77 probably the general practice for several reasons, amongst which may be noted the advisability of guarding against irregularities in the quality of the esparto, and consequent insufficient boiling, as well as the advantage of having some free caustic in the spent liquors to prevent the furring up of the tubes of the evaporating apparatus in the soda recovery department. The following experiments, given by a contributor to the Paper Trade Revieiv some years ago, are interesting as showing the effect of varying proportions of caustic soda used per unit of grass : — Experiments re Yield of Air-dry Bleached Pulp from Oran Esparto. Air-dry Pulp containing 10 per cent, water. No. of Experi- ment. Esparto. Soda Liquor. Conditions of Boiling. Weight Air-dry Pulp. Grams. Dry Pulp on Dry Esparto. Per cent. Bleach- Wt. taken. Grams. Volume, C.C. Per cent. NaaO. Time. Hours. Temp. °C. Pres- sure. Lbs. Powder Per cent. 1 2 3 200 200 200 800 800 800 1-58 2-13 2-69 3 3 3 142 142 142 55 55 55 87-30 80-67 72-00 43-65 40-33 36-00 29-5 18-5 10-5 Practical Data calculated from Experiments. Boiling. Weight of Esparto to give 1 ton Pulp. Cwts. 60 per cent. Caustic Soda required to Digest Esparto. Cwts. Bleaching Powder required to Bleach 1 ton Air-dry Pulp. Cwts. For One Ton of Esparto used. Experi- ment. Time. Hours. Pres- sure. Lbs. 60 per cent. Caustic. Lbs. Bleach- ing Powder. Lbs. 1 2 3 3 3 3 55 55 55 45-8 49-5 55-5 4-30 6-27 8-90 5-26 3-39 1-96 210 282 358 260 156 79 78 THE MANUFACTUEE OF PAPEE Recovery of Spent Liquor. — As it is possible to recover 75 to 80 per cent, of the soda originally used in digesting the esparto, the washing of the boiled grass is conducted on scientific principles in order to ensure a maximum recovery of soda at a minimum cost. The recovery is effected by evaporating down the black liquor, together with the washing waters, to a thick syrupy mass, which can be burnt. The organic and resinous constituents of the esparto which have been dissolved out by the caustic soda, forming the soluble soda compounds, ignite readily, and during combustion the organic soda compounds are converted more or less completely into crude carbonate of soda. It is obvious, then, that the cost of recovery depends mainly on the quantity of weak washing water which has to be evaporated. Consequently methods are devised by means of which the grass is thoroughly washed with as little water as possible, and some of the methods are very ingenious. The spent liquors and washing waters are evaporated to a small bulk in a vacuum multiple effect apparatus, and the thick liquid mass obtained by evaporation is burnt either in a rotary furnace or on an ordinary hearth. Every precaution is taken to effect this operation with a minimum quantity of coal. The burning off of this mass results in the formation of a black substance which is taken away from the furnace and allowed to char or slowly burn until the impure white soda ash, or carbonate of soda, is obtained. Two systems of recovery are in general use, which deserve a brief notice : — Direct Evaporation. — The liquors may be evaporated to a small bulk ready for incineration by treatment in long shallow pans or furnaces, the heat necessary for the process ESPARTO AND STRAW 79 ■^1 80 THE MANUFACTURE OF PAPER being obtained mainly from the combustion of the thick concentrated liquor. The most familiar type of this form of apparatus is the Porion evaporator. The combustion of the concentrated liquor is started by a coal furnace at one end of the apparatus. The thick viscous mass catches fire and burns with a fierce flame, and the heat is utilised in evaporating the weaker liquors which flow continuously through shallow brick troughs, the surface of which is freely exposed to the heat and flames from the hearth where the organic soda compounds produced in the boiling of esparto are being incinerated and converted into soda ash. Under suitable conditions this evaporator is most economical in its results. It can be erected cheaply, and when all the heat is fully used in every possible direction it can be worked at a low cost compared with the more modern multiple effect evaporators. Vacuum Multiple Effect Evaporation. — Advantage is taken of the fact that water boils at a lower temperature in a vacuum than at the ordinary pressure of the atmosphere. There are many forms of apparatus based on this principle, amongst which the most recent is Scott's evaporator. The black liquor from the boilers is pumped through tubes heated externally by high-pressure steam. The liquor is passed into a chamber in which a slight vacuum is maintained, so that immediately on entering, the liquor parts with a good deal of water in the shape of steam. The steam liberated is utilised in producing further evaporation of the partially concentrated liquor, and this operation is repeated several times until the concentration is effected to the desired point. In most cases the actual incineration of the thick liquor is carried out in a rotary furnace when such an apparatus as this is used. ESPAETO AND STEAW 81 Evaporation' Table. Showing the volume of liquor obtained by evaporating 1,000 gallons of weak black lye of density d to a higher density D. Lower Higher Density D (Twaddell) at 100° F. (at 100° F.). 20. 25. 30. 35. 40. 45. 50. 65. 60. 2 3 4 5 6 7 8 9 10 100 150 200 250 300 350 400 450 500 80 120 160 200 240 280 320 360 400 66-6 100 133-3 166-6 200 233-3 266-6 300 333-3 57-1 85-7 114-3 143 171-4 200 228-6 257 286 50 75 100 125 150 175 200 225 250 44-4 66-6 88-8 111-0 133-3 155*5 177-6 200 222 40 60 80 100 120 140 160 180 200 36-3 54-5 72-7 90-9 109 127 145-5 163-5 181-8 33-3 50 66-6 83-3 100 116-6 133-3 150 166-6 Example : — 1,000 gallons of weak liquor at a density of 7° Twaddell are reduced to a volume of 200 gallons having a density of 35° Twaddell, or to a volume of 140 gallons with a density of 50° Twaddell, by evaporation. Preparation of Caustic Soda. — The crude soda ash recovered from previous boiling operations is dissolved in large lixiviating tanks and extracted with hot water. The clear solution obtained after all impurities have been allowed to settle is pumped up into the causticising tanks, where it is converted into caustic soda, the loss due to the amount of soda not recovered being made up by the addition of ordinary soda ash. The causticising pans are large circular iron vessels usually 9 feet diameter and 8 or 9 feet deep, into w^hich a known volume of the recovered carbonate of soda solution is placed. A weighed quantity of ordinary quicklime is then put into a perforated iron cage which is fixed inside the causticising pan at such a level that the whole of the lime is immersed in the solution. The liquor is kept in P. G 82 THE MANUFACTUEE OF PAPEE constant circulation by means of an agitator and heated to boiling point, with the result that the chemical reaction sets in, the carbonate of soda being converted into caustic soda and the lime being thrown out as chalk. When the operation is completed, the steam is turned off and the chalk allowed to settle. The clear liquor is carefully strained off and pumped up into store tanks from which the required quantities are drawn off into the digesters as circumstances demand. Washing. — The grass which has been partially washed in the digester is dug out by the workmen and discharged through a manhole fitted on one side of the digester near the bottom. It is then conveyed in any convenient manner to the breaking engine, in which the grass is more com- pletely washed. This important machine has already been described on page 53. The floor of the vessel slopes slightly upward towards the front of the roll and falls suddenly behind the roll, in order to promote a circulation of the contents of the engine round and round the vessel. A definite weight of boiled grass is thrown into the engine together with a large quantity of fresh water. The circu- lation of the roll draws the mixture of pulp and water between the knives, breaking it up and at the same time discharging it behind the beater roll, and producing a continuous circulation of the mixture in the two sections of the vessels. The dirty water is continuously removed from the vessel by means of a " drum- washer." This is a large hollow drum, the outer surface of which consists of a fine wire cloth, the interior of the washer being fitted with specially curved scoops. The drum- washer is lowered until it is half immersed in the mixture of pulp and water, and as it rotates the dirty water finds its way through the wire cloth, being caught up by the internal scoops and discharged through a ESPAETO AND STRAW 83 pipe to a drain outside the breaking engine. At the same time fresh water is run into the vessel at one end, and the continuous washing of the pulp thus effected. Bleaching. — The clean boiled grass is bleached by means of a solution of chloride of lime. There are several methods used for this purpose, each of which has special advantages of its own, though this is largely a question of local conditions : — (A) The pulp can be bleached in the washing engine directly the grass has been sufficiently cleaned. In this case the flow of fresh water is stopped and as much water as possible removed by means of the drum-washer. The drum-washer is then raised out of the pulp and a known volume of bleaching powder solution corresponding to a definite weight of dry powder is added to the contents of the breaking engine. The amount used depends on the quantity of dry grass in the breaking engine, the usual proportion being 8 to 10 per cent, on the calculated air- dry weight of raw grass. As the stuff circulates round the engine the colour gradually changes from dark yellow to white. The process is sometimes hastened by blowing a small quantity of steam into the mixture and thereby raising its temperature. Considerable care must be exercised in using heat, because pulp bleached quickly by this means is liable to lose colour at the later stages of manufacture. When the pulp has been bleached to the required extent, the drum-washer is again lowered into contact with the bleached pulp, and the latter is thoroughly washed so as to be quite free from traces of bleach and other soluble impurities. (B) Esparto is often bleached in a " Tower " bleaching engine which consists of a tall cylindrical vessel of 9 feet diameter, and 15 or 16 feet deep, at the bottom of which is fixed a small centrifugal pump. G 2 84 THE MANUFACTUEE OF PAPER The boiled grass together with sufficient water and clear bleaching powder solution is placed in the engine ; the centrifugal pump draws the mixture from the bottom of the vessel and discharges it, by means of a large external pipe, direct into the top of the vessel, where, as it falls, it comes into contact with a circular baffle-plate, which distributes the pulp evenly over the surface of the mixture in the vessel. A continuous and rapid circulation is thus main- tained, and the process is said to be very effective. The bleached pulp is subsequently washed free from any traces of bleach. (C) Esparto is frequently bleached by the ''steeping" process. In this case the pulp is washed in the breaking engine, mixed with the required quantity of bleach, and at once discharged through the outlet pipes of the engine into large brick tanks, where the bleach is allowed to act quietly upon the boiled grass. This method produces a pulp of good colour and is economical. Whichever process of bleaching is adopted, it is necessary to remove all the by-products formed during the process, as these soluble by-products if left in the mixture produce a lowering of colour. The presence of small traces of bleaching powder solution can be detected by the use of starch and potassium iodide test papers. If a handful of the pulp after bleaching, when squeezed out, does not turn the test paper violet or blue, then the absence of any free bleach is taken for granted. The slightest trace of bleach will turn such test papers blue or violet according to the amount present. This is the tes usually applied by the men in charge of the bleaching operations. Making Sheets of Esparto Pulp. — For convenience in handling, it is usual to work up the washed and bleached pulp into the form of moist sheets. This is effected on a ESPARTO AND STRAW 85 QQ i'^W^ 86 THE MANUPACTUEE OF PAPER machine known as a " presse-pate," an apparatus which closely resembles the wet end of a paper machine. It con- sists of a set of flat strainers or screens, a horizontal wire similar to the paper machine wire, provided with deckles, the usual couch rolls, and press rolls. The pulp diluted with water is passed through the screens and on to the horizontal wire, where it is formed into a moist sheet, the water draining away from the wire, and also being removed by vacuum pumps. The thick sheet of pulp is carried through the couch rolls and press rolls, being finally wound up on a wooden roller at the end of the machine. In this moist condition it is ready for use in the mill. Dry Esparto Pulp. — When the bleached pulp is intended for export a more elaborate machine is used — to all intents and purposes a paper-making machine — by means of which the continuous sheet of moist pulp is dried and cut up into smaller sheets of suitable size. These dried sheets are packed up in bales containing 2 cwt. or 4 cwt. of dried pulp, then wrapped in hessian and bound with iron wires. Other Methods. — Since the yield of esparto pulp from the raw material is less than 50 per cent, and it requires 45 cwt. of grass to make one ton of finished pulp, methods have been devised for treating the grass in the green state in the districts where it is grown, but so far nothing has been done on a large scale. The isolation of the cellulose hy alkaline treatment in the cold has been suggested, but the method never passed beyond the experimental stage. This process was indeed first mentioned by Trabut, who many years ago considered that the removal of non-fibrous constituents from fresh grass could be readily accomplished by the less drastic treatment of the esparto with alkaline carbonates of soda and potash at ordinary temperatures. ESPAETO AND STEAW 87 The production of esparto pulp hy bacteriological fermenta- tion is an idea of later date. According to the inventor, the grass is crushed mechanically by means of rollers and then immersed in sea water inoculated with special bacillus obtained from esparto, and gradually resolved into cellulose and soluble by-products by fermentation which is complete in about eleven days. The commercial value of this idea has not yet been demonstrated. Esparto Pulp : Microscopical Features. The pulp of esparto when examined under the microscope is easily recognised, first by the characteristic appearance of the long slender cylindrical-shaped fibres, and secondly by the numerous cells always present. These cells consist of cuticular vessels with serrated edges, and also of small pear-shaped seed hairs, the shape of which is a ready means of identifying esparto. An examination of the transverse section of the raw material indicates the source of these pear-shaped vessels. Test for Esparto in Papers. — Paper containing esparto fibre may be tested by means of a weak solution of aniline sulphate. The suspected paper is gently heated in the test reagent, and if esparto is present the paper turns a rose-red or pink colour, the depth of colour being a measure of the amount of esparto. Most of the modern book papers are prepared from chemical wood pulp and esparto mixed in varying proportions, and while this test can be used as a means of detecting a small or a large proportion of esparto, a microscopical examination is required for a more accurate estimation. The proportions used by the paper-maker depend upon the weighing out of the wood pulp and esparto more or less accurately, while the microscopical test is based upon the relative proportions as represented by the volume of fibres 88 THE MANUFACTUEE OF PAPER of each class on the glass slip placed under the microscope. Since the wood pulp consists of a number of broad flat ribbon-like fibres, and the esparto of small cylindrical fibres, Fig. 25. — Esparto Pulp. considerable practice is necessary in making a proper analysis of the two constituents in paper. Steaw. The use of straw for the manufacture of paper was first brought prominently into notice about the year 1800 by STEAW 89 Matthias Koops, who published a book printed on paper made from straw, but it was not until 1860 that this material was used in any large quantity. Straw is now converted into a bleached paper pulp for Fig. 26. — A Cylindrical Digester for Boiling Fibre. news and printings, and is also utiUsed for the manufacture of straw boards. The production of a white paper pulp from straw is carried out in a manner similar to that used in the case of esparto fibre, viz., by digestion with caustic soda under pressure and subsequent bleaching. As the straw contains considerable quantities of siliceous matter, the chemical treatment necessary to reduce the material to paper pulp is more severe, a stronc^er solution of caustic soda being used, 90 THE MANUFACTURE OF PAPER and the process of digestion being carried out at a higher temperature. For the best quality of straw cellulose, the material is cut up into small pieces by machines which resemble an ordinary chaff-cutter, and the knots taken out by a separating machine. In most cases, however, the whole straw is simply cut up into small lengths of about one to two inches long, and placed at once in the digester. When the straw is contaminated with foreign weeds, sand, husks, and similar substances, as is usually the case, it is care- fully hand-picked by girls, who remove these impurities, which tend to produce particles of unbleached matter in the finished pulp. The expense of this preliminary cleaning process is more than compensated for by the enhanced value of the bleached straw pulp. Digesting. — The cut straw is boiled in rotary cylindrical or spherical vessels, stationary upright boilers of the vomit- ing type being seldom employed because the circulation of the caustic soda liquor does not take place freely with straw packed in the latter. As the material is very bulky, some of the liquor is first put into the boiler and the steam admitted while the straw is being thrown in. By this means the straw is softened and reduced in bulk, so that a larger quantity can be added before the digester is quite fulL The full amount of caustic soda is then made up by further additions of liquor, and the contents of the digester heated by high-pressure steam for four to six hours. The conditions of treatment are shown by the following trial : — Amount of straw . . . 5,600 lbs. Caustic soda, 20 per cent. . . 1,120 lbs. The caustic soda was added in the form of a liquor, STEAW 91 having a volume of 2,012 gallons and a specific gravity of 1-055. Time of boiling .... 5 hours. Pressure 60 lbs. Washing. — The boiled straw is discharged into large tanks placed below the digester and washed with hot water, the smallest possible quantity being used consistent with complete washing in order to prevent the accumulation of large volumes of weak lye. The spent liquor and washing waters are drained off into store tanks and evaporated in a multiple effect apparatus by the same process as that used for esparto pulp. The last washings are usually run away because the percentage of soda in them is too small to pay for the cost of recovery. The final washing of the straw pulp is completed by the use of a breaking engine or potcher. As straw pulp con- tains a large proportion of cellular matter which cannot be regarded as true fibres, there is always a danger of con- siderable loss in yield if the use of the breaking engine is extensively adopted, because the short cells escape through the meshes of the drum-washer. The washing is most economically effected in the tanks if a good yield of pulp is required. Separating out Knots. — The broken pulp from the break- ing engines is diluted with large quantities of water and pumped over sand traps in order to remove knots and weeds which have resisted the action of the caustic soda. These traps consist of long shallow trays, perhaps sixty to eighty yards long, one yard wide, and nine inches deep, containing boards which stretch from side to side, sloping at an angle, and nailed to the bottom of the trays. The dilute pulp flows through the trays, leaving the heavy particles, knots, and foreign matter behind the sloping 92 THE MANUFACTURE OF PAPER boards, and finally passes over the strainers, which retain any large coarse pieces still remaining. Making Sheets of Pulp. — The mixture from the strainers contains a large excess of water which has to be removed before the pulp can be bleached. For this purpose a wet press machine (see page 103) or a presse-pate (see page 85) is employed, and the wet sheets of pulp are then ready for bleaching. Bleaching. — The process by which the pulp is bleached is exactly similar to that used for treating esparto. From 1870 to 1890 large quantities of straw were used for the manufacture of newspaper in conjunction with esparto and wood pulp, but the price of the material was gradually advanced so that it could not be used with advantage, especially as the production of wood pulp gave a material which was much cheaper, and which could be utilised at once without chemical treatment. In the manufacture of newspaper the tendency during recent years has been to make the paper mill operations as mechanical as possible and to dispense with the preliminary operations which are essential for the manufacture of half- stuff, the chemical processes being left in the hands of the pulp manufacturers. The manufacture of straw cellulose is now practically confined to Germany, but small quantities of the bleached straw cellulose are imported because the pulp imparts certain qualities to paper which improve it, notably in making cheap printing papers harder and more opaque. Microscopical Features of Straw. The paper pulp obtained from straw consists of a mixture of short fibres together with a large proportion of oval- shaped cells. The fibres are short and somewhat resemble esparto, but the presence of the smaller cells is a sure MICROSCOPICAL FEATURES OF STRAW 93 indication of the straw pulp. The fibres themselves closely resemble the fibres of esparto, but as a rule the latter are long slender fibres, while the straw fibre is very often bent and twisted or slightly kinked. \ .-..^■^^^ppCs^./ M t \ /j^^^^"^^ m M^^^^?^ rP iFa/ ^ 1 Wr^ s //£>>^^^ wJ^ fw^t^^ rV ^^Si^r ' ^ V jyjf^ / ^^--0>4 Mi mh^^*-6 27-3 8-3 lS-2 77-7 66-6 55*5 114 33-3 22-2 IM 8. 7. 6. 5. 4. 3. 2. 100 128-5 166-6 220 300 133-3 700 87-5 111-3 150 200 '^75 400 650 75 100 133-3 180 250 3(56-6 600 62-5 85-7 116-6 160 225 333-3 550 50 7M 100 110 200 300 500 37-5 57-1 83-3 120 175 266-6 450 25 42-8 66-6 100 150 233-3 400 12-5 28-5 50 80 125 200 350 U-2 33-3 60 100 166-6 300 16-6 10 75 133-3 250 20 50 25 100 33-3 200 150 100 1,500 1,100 1,300 1.200 1,100 1,000 900 800 700 600 500 400 300 Anticlilors. — The residues of chlorine which may be left in pulp after bleaching are frequently neutralised by the use of substances termed antichlors, which react with the calcium hypochlorite, converting it into chlorides. The sodium hyposulphite is the most frequently used 164 THE MANUFAOTUEE OE PAPER antichlor, the reaction between this and hypochlorite resulting in the formation of calcium sulphate and sodium chloride ; 100 lbs. of commercial bleaching powder will require 30 lbs. of crystallised sodium hyposulphite. The sulphites of soda and lime also act as antichlors, reducing the hypochlorite of calcium into sulphate of lime or soda. The chief advantage of the use of sulphites is to be found in the fact that the substances obtained by the reaction are neutral. The best practice in bleaching is to avoid the necessity for using any forms of antichlors by careful regulation of the bleaching process. It has already been suggested in 23revious references to bleaching that the desired results are obtained when the pulp and bleach are left in contact with one another in tanks or drainers until the bleach is completely exhausted, the residual salts in solution being removed by thorough washing. Gelatine. — For animal- sized or tub-sized papers gelatine is used. It can be prepared by the paper-maker from hide clippings, sheep skins, bone, etc., or can be purchased ready made. Beadle gives the following interesting details as to the amount of gelatine which can be obtained from wet hide pieces : — Weight or Wet Hide Pieces, 2,128 lbs. Draught. Gallons. Per cent. Gelatine in Solution . Weight of Gelatine. Lbs. . 1 2 3 and 4 mixed 126-48 128-96 135-20 6-775 6-052 9-446 85-64 78-04 127-63 Total .. 390-64 291-31 Percentage of gelatine on weight of wet skins = 13*69. CHEMICALS USED IN PAPEE-MAKING 165 A similar trial on the same class of wet hide pieces gave a yield of 13'23 per cent. Two trials, of a somewhat different class of wet hide pieces, gave respectively 13"11 and 12'8 per cent. The temperature of the draught water should be approxi- mately as follows : — Draught. At Beginning. At End. 1 2 3 and 4 120° F. 130° F. 140° F. 150° F. 160° F. 180° F. In the final draught it is often necessary to use live steam at the finish, but this should be avoided if possible. The water contained in wet hide pieces varies from 77 to 90 per cent, in the different pieces, but in the bulk the average may be taken at 85 per cent. Casein. — Casein is the nitrogenous principle of milk, and belongs to the class of proteids which are definite com- pounds of oxygen, hydrogen, carbon, and nitrogen, forming the basis of the most important constituents of all animal fibres, albumen, casein, and gluten. A very pure forni of casein is cheese made from skimmed milk. Casein belongs to that class of albumens which are soluble in water, e.g., egg albumen, blood albumen or serum, and lactalbumen, or milk albumen ; these are mostly precipi- tated from solution by saturation with sodium chloride (common salt) or magnesium sulphate ; but they are all coagulated by heat. By the action of rennet on milk the ^Droteid or albumen principle is converted into a curd (casein). This curd, when freed from fats, is insoluble in water, but is soluble in dilute acids, or alkalies, or alkaline carbonates, from 166 THE MANUFACTUEE OE PAPEE which substances, however, it is reprecipitated by acidula- tion. Instead of the above method, casein may be pre- cipitated from milk by saturation with sulphate of magnesia, and washing the precipitate with a solution of that salt until the washings contain no albumen, and then redissolv- ing the prepared casein by adding water. The salt still adhering to the precipitate enables it to dissolve. On a large scale the casein is usually prepared by treating the milk with acid. Casein is readily dissolved by alkalies and alkaline carbonates, borax, boracic acid solution, caustic soda, and bicarbonate of soda. Starch. — This substance is used in many classes of paper for improving the surface and finish. It is added to the pulp in the beating engine in the dry form as powder, or in the form of starch paste, produced by boiling the starch in water. The viscosity of the starch paste is somewhat increased by the addition of a small quantity of alkali, but due care must be exercised in boiling, which should only be carried out sufficiently to cause the starch granules to burst, as any excessive boiling causes the starch paste to lose some of its viscosity. The presence of starch in paper is detected by the blue coloration produced when the paper is dipped in^o a weak solution of iodine. The determination of the exact per- centage of starch in a paper is a matter of some difficulty. Silicate of Soda. — The precipitation of gelatinous silica upon the pulp in the beating engine is generally regarded as favourable to the production of a sheet of paper having what is known as a harder finish. The precipitation is effected by adding a solution of silicate of soda to the beat- ing engine, with the subsequent addition of sufficient sulphate of alumina to react with the silicate of soda. CHEMICALS USED IN PAPEE-MAKING 167 Analysis of Commercial Alums. (Griffin and Little.) - (1) (2) (3) (i) Insoluble in water 05 10-61 0-11 0-56 Alumina (AI2 0,s) .... 15-47 14-96 11-64 16-58 Iron protoxide (Fe 0) . 02 0-13 0-06 — Iron sesquioxide (Fe2 Oh) 000 1-08 1-17 0-04 Zinc oxide (Zn 0) . — — — Soda(Na.2 0) .... 1-72 0-57 4-75 0-56 Magnesia (Mg 0) . — — 0-45 — Sulphuric acid (SO3) combined 37-26 37-36 35-98 39-17 Sulphuric acid (SOg) free — 1-08 5-13 — Water by difference 45-48 34-21 40-71 43-09 100-00 100-00 100-00 10000 Sizing test (parts of dry neutral rosin size precipitated by one part of the alum) 3-32 3-47 3-19 3-71 Table showing Value of Solutions of Aluminium Sulphate. Pounds per 100 gallons. 'S Pounds per 100 gallons. 1 Sulphate of Sulphate of $ H AI2 O3. SO3. Alumina containing 15 per cent. AI2 O3. H AI2 O3. SO3. Alumina containing 15 per cent. AI2 O3. 1 1-4 3-3 9-0 14 20-3 47-3 135-0 2 2-8 6-5 19-0 16 23-1 53-8 155-0 3 4-2 9-8 28-0 18 26-2 60-3 172-0 4 5-6 13-0 37-0 20 29-4 68-5 196-0 5 7-0 16-3 47-0 25 37-1 86-5 247-0 6 8-4 19-6 56-0 30 44-8 104-4 299-0 ■7 9-8 22-8 65-0 35 53-2 124-0 355-0 8 11-2 26-1 75-0 40 60-9 142-0 405-0 9 12-6 29-4 84-0 45 68-6 159-9 456-0 10 14-0 32-6 93-0 50 77-7 181-0 578-0 11 15-4 35-9 103-0 00 86-1 200-6 575-0 12 16-8 39-1 112-0 60 95-2 221-8 635-0 168 THE MANUFAGTUEE OE PAPER Alum. — Alum is one of the most important substances required in the manufacture of paper, its chief function relating to the sizing of paper. Various forms are utilised for this purpose, the purest being sulphate of alumina, required for high grade papers, and the cheaper form known as alum cake, for news and common printing. The alum is manufactured on a large scale by heating cbina clay or bauxite with sulphuric acid. This reaction gives sulphate of alumina together with silica. If the mass is heated to dryness, it is sold under the name of alum cake. If the mass is extracted with hot water and the insoluble silica filtered off, the solution can be evaporated down for the production of suljjhate of alumina, which is sold in the form of large cakes or in the form of crystals. By careful selection of raw material a sulphate of alumina can be prepared almost entirely free from iron. The presence of the latter is undesirable, since on exposure to air the sulphate of iron produced during the manufacture of the alum is slowly oxidised and turns brown. Ultimately this affects the colour of the finished paper. Alum is added to solutions of animal size^or gelatine in order to thicken the solution and render it more viscous. It also acts as a preservative, and is used for regulating the absorption of the gelatine by the paper, the penetration effects being materially varied by the extent to which the alum is utilised. In the process of engine sizing, a term applied to the application of rosin size on account of the fact that the process is completed in the beating engine, alum plays an important part. The mere addition of the prepared rosin soap to the mixture of pulp and water in the beating engine does not size the paper, but the alum precipitates the rosin from its solution, producing a complex mixture said to consist of resinate of alumina and free rosin particles, and CHEMICALS USED IN PAPEE-MAKING 169 subsequently the heat of the paper machine drying cyHn- ders renders the paper more or less impermeable to moisture. The appearance and tone of paper, more particularly of coloured papers, are brightened by the use of an excess of alum over and above that necessary to precipitate the rosin soap. Rosin Size. — This substance is used chiefly for the sizing of news and cheap printing papers, and is also employed together with gelatine for the commoner writing papers. It is prepared by boiling rosin with carbonate of soda under various conditions. Eosin, sometimes called colophony, is obtained from the sap of certain firs and pine trees. This on distillation yields spirits of turpentine, leaving behind as a residue the mixture of substances to which is given the name rosin. It behaves as an acid, and therefore will combine with certain alkaline oxides, producing soluble resinates. The nature of the rosin soap used in the paper mill varies according to the conditions under which the size is prepared. If a large proportion of rosin is used, then the size obtained consists of a mixture of resinate of soda together wilh free rosin dissolved in the solution. If the proportion of rosin is small compared with the amount of carbonate of soda, the composition of the final mixture is quite different. The difference in treatment results in the formation of — (A) Neutral Size, prepared by boiling a known weight of rosin with sufficient alkali to combine with it and form a neutral resinate of soda. Theoretically this may be obtained by using 630 parts of rosin to 100 parts of soda ash. It is doubtful how far the reaction is completed so as to produce an exactly neutral solution containing only resinate of soda. 170 THE MANUFACTUEE OE PAPER (B) Acid Size. — When the proportion of rosin is largely increased the soda becomes converted into the alkaline resinate, and the excess of rosin is gradually dissolved in the resinate formed. The practical operations necessary for the preparation of the size are comparatively simple. In the case of size containing relatively small percentages of free rosin, the boiling is conducted in open vessels, but for the manufac- ture of rosin size containing large proportions of free rosin boiling under pressure in closed vessels must be resorted to. With the open pan process a steam jacketed pan is used, and the required quantity of alkali, dissolved in water, is placed therein and heated to boiling point. The rosin well powdered is added in small quantities from time to time, this being effected cautiously in order that the carbonic acid gas set free during the process may readily escape. The rosin is generally completely saponified after four or five hours' boiling. It is then passed through strainers into store tanks, from which it is drawn into the beating engines as required. In the case of rosin boiled under pressure a cylindrical vessel provided with a manhole at the top is used. The correct amounts of alkali and water are put into the digester, and also the rosin in a powdered form, the digester being fitted with a perforated plate placed about two feet above the bottom of the vessel in order to prevent the rosin forming into a hard mass at the bottom of the digester. It is possible in this way to manufacture a thick size containing 30 or 40 per cent, of free rosin and a compara- tively small proportion of water. Many paper mill firms prefer io purchase such size ready made. The most recent modification of the ordinary rosin size is a compound prepared by treating rosin with silicate of soda. This alkali dissolves rosin readily, and the soap CHEMICALS USED IN PAPEE-MAKING 171 obtained when suitably diluted with water decomposes in the beating engine on the addition of aluminium sulphate, with the precipitation of a gelatinous silica which assists in hardening the paper. Bacon has patented a process in which powdered rosin is melted down with dry crystalline silicate of soda. The resultant product is ground to a fine powder, which is then ready for use. It dissolves easily in water, and when decomposed with the proper proportion of alum gives a gelatinous viscous mass said to have excellent sizing properties. The advantages of a dry powdered rosin size readily soluble in water are obvious. Loading. — The term ''loading" is applied to the various substances which are employed for the purpose, as it is commonly supposed, of making paper heavy. But china clay and similar materials are not added simply in order to give weight to the paper, since they serve to produce opacity and to improve the surface of papers which could not be satisfactorily made unless such materials were used. Examinatiun of Paper for Loading. — If a piece of paper is crumpled up, placed in a small crucible, and then ignited until all the carbonaceous matter has been burnt off, a residue is left in the crucible which may be white or coloured. This is usually termed the ash of the paper. The amount of ash present is determined by taking a weighed quantity of paper and weighing the residue obtained. Special appliances can be obtained for making rapid determinations of the ash in paper, but for occasional analyses they are not required. China Clay. — This is the best known and most commonly used loading. The purest form of this material is kaolin, a natural substance formed by the gradual decomposition 172 THE MANUFACTUEE OF PAPEE of felspathic rocks arising from exposure to the long- continued action of air and water. The clay occurs in great abundance in Dorset, Cornwall, and Devon, the southern counties in England, where the most famous deposits are found. The natural mineral is levigated with water, and the mixture allowed to flow through a series of settUng ponds, so that the clay gradually settles in the form of a fine deposit. The clay is dried and packed in bags. Its value is controlled largely by the purity of its colour and its freedom from grit and sand. It is essentially a silicate of alumina, having the approximate composition — Silica (Si O2) . . . . 43-00 Alumina (AI2 O3) • . 35*00 Combined water .... lO'OO Moisture and impurities : . 12'00 100-00 The specific gravity of the dry substance is 2*50. It is utilised as a loading in all kinds of paper, and forms also the main ingredient in the coating found on ordinary art and chromo papers. Ash containing China Clay. — In news, cheap printings, and common art papers the ash almost invariably contains china clay. This substance is insoluble in dilute acids, but is acted upon by concentrated sulphuric acid when digested for some time. A simple test for the presence of china clay in ash is the blue coloration which is obtained wheii the ash after being ignited is gradually heated with a fe^ drops of solution of cobalt nitrate. China clay can be decomposed by fusion with carbonate of soda in a crucible. By this means silicate of alumina is decomposed, and the alumina goes into solution, the silica remaining as an CHEMICALS USED IN PAPEE-MAKINa 173 insoluble residue. The filtered solution is boiled with an excess of ammonia which gives a gelatinous precipitate of aluminium hydrate. Sulphate of Lime. — This compound is valued chiefly for its brilliancy of colour, being used in high-class papers. It is slightly soluble in water, to the extent of about 23 lbs. in 1,000 gallons, and this fact must be taken into account when the material is added to the pulp in the beating engine. It occurs naturally in a variety of forms, such as gypsum, alabaster, selenite, the first of which when finely powdered is sold to the paper-maker as gypsum, powdered plaster, and under other fancy names. It can be prepared artificially by adding sulphuric acid to solutions of calcium salts ; and the precipitated product so obtained is sold as terra alba, pearl hardening, satinite, mineral white, etc. The tests for sulphate of lime in paper ash are based upon the following reactions : — Calcium sulphate is soluble in dilute hydrochloric acid. The addition of a few drops of barium chloride to the solution produces a dense heavy precipitate, indicating the sulphate. A small quantity of ammonium oxalate solution added to another portion of the dissolved calcium salt pre- viously neutralised with ammonia produces a precipitate and indicates calcium. A microscopic test of paper for the presence of sulphate of lime is based upon the slight solubility of the salt in water. The paper is boiled with some distilled water. The water is evaporated to a small bulk and transferred to a glass slip, and the gradual formation of characteristic sulphate of lime crystals can be seen by means of the microscope as the water cools down. French Chalk, — This material is prepared by grinding 174 THE MANUFACTUEE OF PAPEE talc into a fine powder, and possesses a good colour and i somewhat soapy feel. It is a silicate of magnesia, having the approximate composition — Silica (Si O2) . Magnesia (Mg 0) Water Traces of oxides, etc. 62-00 33-00 4-30 0-70 100-00 Other silicates of magnesia used for paper-making are agalite and asbestine, the latter being a finely ground asbestos. The composition of asbestos is approximately — - Italian. Canadian. Lime and magnesia Silica Oxides of iron and alumina . Total water ..... Traces of soda, etc. 38-0 42-0 50 13 2-0, 33-0 41-0 12-0 12-0 3-0 100-00 100-00 CHAPTEE IX THE PROCESS OF BEATING Introduction. — The process of beating has for its object the complete breaking down of the bleached puljD to the condition of single fibres, and the further reduction of the fibres, when necessary, into smaller pieces. The disinte- gration of the material is essential for the production of a close even sheet of paper, and the amount of beating required varies greatly according to the nature of the raw material, and the class of paper to be produced. The textile trade, on the other hand, depends on a raw material composed of strong fibres, or of filaments cha- racterised by great length, and any processes of treatment which tend to reduce the length of such fibres are carefully avoided, and it is therefore obvious that fibres which are of no value for textile purposes can be appropriated for paper- making. Condition of Fibres. — The great differences in the physical characteristics and structure of the fibres employed for paper-making suggest that the possible variations in the final product obtained by beating are very numerous. This is a well-known fact, and it is further to be noted that this mechanical operation brings about not merely alterations of a physical order, but introduces some interesting and important chemical changes. Of the better-known materials linen, with an average fibre length of 28 mm., the structure of which lends itself to considerable alteration by beating, is in marked contrast 176 THE MANtJFACTUEE OE I>At>EE to esparto, the fibre length of which is only 1'5 mm. If the process of beating a linen rag merely resulted in the cutting of all the fibres of 28 mm. long into short fragments of 1*5 mm., there would be nothing remarkable in it, but the changes which occur in reducing the long linen fibre to 1*5 or 2'0 mm. are of a far more important character than this. Eaiiy Methods.- — In the early days of paper-making the disintegration of the half-stuff was effected by a true ''beating" process, the rags being subjected to the action of heavy stampers, which broke up the mass of tangled fibre into a uniform pulp. The fibres for the most part retained their maximum length in this operation, which was exceedingly slow and tedious, though at the same time giving a sheet of paper of remarkable strength. The nearest imitation of these old-time rag papers is to be seen in the well-known Japanese papers, which are extraordinarily strong. Some of these the writer has examined in order to determine the length of the fibre. The sheets when held up to the hght appear " cloudy " and " wild " owing to the presence of the long fibres, which have only been separated or teased out by the primitive methods of beating used, and not completely disintegrated. Conditions of Beating.— Ahout a.d. 1700 there began a great epoch in the history of paper-making. With the invention of the Hollander engine about a.d. 1670, the pro- cess of disintegration was greatly hastened, because it was possible to reduce the half-stuff much more readily. The substitution of the idea of plain "beating" by a principle which combined the gradual isolation of the individual fibres with a splitting up of those fibres lengthwise and crosswise was not only an advantage in point of economy of time and cost, but also a material advance in the possi- bilities of greater variations in the finished paper. THE PEOCESS OF BEATING 177 The conditions of the process of beating carried out Avith a Hollander permit of considerable alteration, so that these changes in the fibre are not surprising when properly under- stood. In fact, it is now conceded that a close study of the theory and practice of beating is likely to bring about still more remarkable improvements in this important depart- ment of the paper-maker's work. The quality and character of the paper made may be varied with — (1) The origin of the raw material, e.g., rags, esparto, or wood ; (2) The condition of the material, e.g., old or new rags, green or mature esparto, mechanical or chemical wood pulp ; (3) The time occupied in beating, e.g., four hours for an ordinary rag printing and twelve hours for a rag parch- ment ; (4) The state of the beater knives, e.g., sharp tackle for blottings and dull tackle for cartridge papers ; (5) The speed of the beater roll, also its weight ; (6) The rate at which the beater roll is lowered on to the bedplate ; (7) The temperature of the contents of the engine. The Beater Roll. — If the beater roll is fitted with sharp knives, and this is put down close to the bedplate quickly, the fibres are cut up short, and they do not assimilate the water. If the roll is fitted with dull knives, or " tackle," as it is sometimes called, and it is lowered gradually, the fibres are drawn and bruised out without being greatly shortened. In this condition the stuff becomes very "wet," or "greasy," as it is termed. The cellulose enters into association with water when beaten for many hours, and the pulp in the beating engine changes into a curious greasy-like mass of a semi-transparent character. Eag pulp beaten for a long time produces a hard, translucent, dense sheet of paper. Flax thread beaten 48 to 60 hours is used in practice p. N 178 THE MANUFACTUEE OF PAPEE for the manufacture of gramophone horns and similar purposes. Soft porous papers hke blottings, filtering papers, heavy chromos, litho papers, antiques, light printings, are made from pulps which are beaten quickly with the roll put down close to the bedplate soon after the stuff has been filled in. With strong, dense, hard papers, such as parchments, banks, greaseproofs and the like, the pulp is beaten slowly and the roll lowered gradually. The nature of the pulp and the time occupied in beating are also important factors in producing these different papers, three to four hours being ample for an ordinary wood pulp printing, whereas a wood pulp parchment requires seven to eight hours. Beating Pulps Separately. — The use of esparto and wood pulp in conjunction with one another, or blended with rag, has introduced new problems into the question of beating. Perhaps the most important of these is the advisability of beating the pulps separately and eventually passing them through a mixer of some kind before discharging into a stuff chest. The necessity for differentiating the amount of beating is already partly recognised when very dissimilar pulps, such as strong rag and esparto, are blended, but the whole subject ought to be carefully studied by the paper- maker and investigated on its merits from the standpoint of "beating effects," apart from questions of cost and expediency. The former fully understood and exhaustively examined by practical tests would of course only be de- veloped if proved to be advantageous. The field of research in this direction has not yet been seriously explored. With the enormous consumption of wood pulps of varying quality made from many different species of wood by several processes, there is ample room for interesting and profitable enquiry, particularly as the THE PEOOESS OF BEATING 179 types of beating engine are so namerous. The effects produced by the Hollander, the refiner, the edge runner, the stone beater roll, and other mechanisms, are all of varying kinds. Effect of Prolonged Beating. The importance of a knowledge of the precise effects pro- duced by the beating of pulp cannot be emphasised too EiG. 46. — Cotton Pulp beaten 8 hours. much, and any contributions to the subject along the lines of special research will be welcomed by all students of cellulose. Some experiments were conducted by the writer in 1906 with cotton rags, in order to determine the results obtained N 2 180 THE MANUFACTURE OF PAPEE by beating the pulp for a prolonged period under exact and specific conditions. The cotton rags, of good quality, were boiled with caustic soda in the usual way for six or seven hours, at a pressure of 15 to 20 lbs., washed and partially broken down in the rag Fig. 47. — Cotton Pulp beaten 37 hours. breaker, and finally bleached, made into half-stuff, and then transferred to a Hollander beating engine. The particular conditions specified for the beating opera- tion were that the beaterman should manipulate the pulp according to his usual routine for the manufacture of the paper which he was accustomed to make from these rags. In this case the routine process meant beating for eight hours, by which lime the pulp was ready for the paper machine. In the ordinary course the pulp would be THE PEOOESS OF BEATING 181 discharged into the stuff chest, and converted into a strong, thin, bank paper. Durino- the prolonged beating the pulp became very soft and " greasy," and when made up into sheets the paper as it dried exhibited remarkable differences in shrinkage, the dry sheets obtained from pulp beaten thirty-seven hours being much smaller than those obtained from pulp beaten only four or six hours. The actual shrinkage is shown in the following table : — Houi's. Area of Sheet. Loss of A reel. ReLative Areas. Shrinkage Sq. mm. Sq. mm. Deckle 100 per cent. 26,384-0 100-0 4 26,076-0 308-0 98-9 1-1 6 25,520-1 863-9 96-7 3-3 8 25,160-0 1,224-0 95-4 4-6 . 10 24,794-8 1,589-2 93-9 6-1 13 24,467-4 1,916-6 92-8 7-2 15 24,215-2 2,168-8 91-8 8-2 17 24,024-0 2,360-0 90-9 91 19 23,616-2 2,767-8 89-6 10-4 21 23,616-0 2.768-0 89-6 10-4 23 23,535-7 2,848-3 89-3 10-7 25 23,329-9 3,054-1 88-5 11-5 27 22,920-5 3,463-5 86-9 13-1 29 22,831-2 3,552-8 86-5 13-5 31 22,492-9 3,891-1 85-3 14-7 33 21,917-2 4,466-8 831 16-9 35 21,226-1 5.157-9 80-5 19-5 37 20,778-8 5,605-2 78-8 21-2 If these results are plotted in the form of a curve the relation between the period of beating and the shrinkage in area is clearly shown. For the first twenty hours the shrinkage is proportional to the period of beating, after which the curve assumes an irregular shape, show- ing a tendency for shrinkage to proceed at a faster rate. 182 THE MANUFACTURE OF PAPER Weight and Suhstance of the Paper. — The shrinkage of the paper after prolonged beating indicates a closer and denser sheet, so that for papers of equal thickness the weight per unit area was much greater in the case of the pulp beaten for the full period. The results obtained are very interesting, and the following summary for a few of the readings obtained will serve to show the alteration effected. Weight of Thickness of r;,„vv,^ ,,„,. Hours. 20,000 sq. mm. 1 Sheet. ,„ ^'t" Giams. mm. ^^- ™*^^^®- Lbs. per ream 480 ^heets, 20" X 30". Class A 8-10 Ins. Class B 19-21 his. Class C 33-35 hrs. 1-875 -183 93-75 2-043 •189 102-15 2-203 •189 110-15 38-23 41-05 44-93 Sizing and Glazing Effects. — The behaviour of the water- leaf paper after sizing and glazing gave so];ne interesting results. In the first place, the effect of the altered density of the paper is strikingly shown by the amount of the size absorbed. Certain selected sheets w^ere passed through a solution of ordinary gelatine in the usual way, and subse- quently dried. The amount of gelatine absorbed differs in a remarkable degree, as shown in table. Te)isile Strength of the Paper. — It is interesting to note that the tensile strength of the waterleaf papers appears to remain fairly constant throughout the whole period of beating. But this uniformity is greatly altered by the operations of sizing and glazing. THE PEOOESS OF BEATING 183 Percentage of Air-dry Gelatine absorbed by the Wateuleaf Sheets. Hours. Pei'centayo of iSize ab ■iorbed. Mean. ] St Trial. 2nd Trial. 3rd Trial. 8 O'O 6-0 6-2 5-9 10 5-4 6-8 &o 6-2 19 8-8 5-0 4-5 4-4 21 4-8 3-9 •J-6 4-4 S3 2-7 1-7 2-4 2-3 3d 2-4 1-9 1-7 2-0 These results are rather remarkable. Tiie prolonged beating does not seem to have affected the tensile strength of the waterleaf, and the practical loss of strength which actually occm^s in the more completely finished paper does not manifest itself until after the sizing process. The importance of the gelatine as a factor in the ultimate strength is thus clearly and strikingly demonstrated. Tests for Strength on Original Waterleaf Paper. Mean result of Mean Strength Hours. Readings. of the Paper. Lbs. Lbs. 8 a 14-1 12-1 b 10-1 10 a 15-4 13-2 b 10-9 19 a 16-5 14-0 b 11-4 21 a 15-2 14-0 b 12-8 33 a 13-4 12-4 b 11-4 35 a 14-5 13-G b 12-'; 184 THE MANUFACTURE OF PAPER Tests foe, Strength on Papers, Sized only. Mean result of Mean Strength Hours. Readings. of the Paper. Lbs. Lbs. 8 a 22-7 20-0 b 17-3 10 a 28-0 23-2 b 18-0 19 a 22-5 21-0 b 19-5 21 a 26-0 21-7 b 17-5 33 a 15-0 15-0 b 15-0 35 a 14-2 15-3 b 16-5 Tests eor Strength on Paper Sized and Glazed. Mean result of Mean Strength Hours. Readings. of the Paper. Lbs. Lbs_^ 8 a 25-8 23-6 b 21-4 10 a 28-4 23-6 b 18-9 19 a 27-0 22-9 b 18-9 21 a 24-9 22-7 b 20-6 33 a 16-1 15-2 b 14-4 35 a 17-5 16-2 b 15-0 THE PEOCESS OF BEATING 185 It may also be noticed that the strength of the finished paper after twenty hours' beating, as in class B, is equal to that of the 23aper after nine hours' beating, as in class A. This is curious, especially in view of the fact that the per- centage of gelatine in the papers of class B. is only 4*4 per cent, as against 6'0 per cent, in class A. The relation of the percentage of gelatine to the period of beating thus becomes a matter of interest, and well worth Fig. 48. — Plan and Sectional Elevation of a " Hollander.' investigation. The figures are suggestive of further experimental research along definite lines. Developments in Beating Engines. — Since the introduc- tion of the Hollander beating engine, about a.d. 1670, other types of beater almost too numerous to mention have been devised to supersede it, but the fact remains that the principle of the original Hollander and its general design are still adhered to in the engines used by paper-makers for high-class work. The alterations and improvements which have taken 186 THE MANUFACTUEE OF PAPER place during the last fifty years relate chiefly to the modi- fications naturally arising from the introduction of fibres not requiring such drastic treatment as rags. The machines now in use for reducing half-stuff to beaten palp ready for the paper machine may be classified as follows : — (1) Beaters of the Hollander type, in which the circula- tion of the pulp in the engine and the actual beating process are both effected by the beater roll. (2) Beaters of the circulator type, in which the movement of the pulp is maintained by a special contrivance, and the beater roll used only for beating. (3) Beaters of the stone roll type in which the roll and bedplate are either or both com- posed of stone, granite, or similar non-metallic substance. (4) Eefiners, containing conical shaped beater rolls working in a conical shell fitted with stationary knives. The Hollander. — This beating engine in its simplest form consists of an oval shaped trough, divided into two channels by a " midfeather," which does not, however, reach com- pletely from one end to the other. In one of the channels the bed of the trough slopes up slightly to the place where the " bedplate " is fixed. The bedplate consists of a number of stout metal bars or knives firmly fastened into an iron frame, which lies across this Fig. 49. — Beating Engine with Four Beater Rolls. THE PEOCESS OF BEATING 187 channel. The heater roll, a heavy cast-iron roll provided with projecting knives or hlades arranged in clumps of three around the circumference, and supported on bearings at each side of the engine, revolves above the bedplate with the knives adjusted to any required distance from it, the raising or lowering of the beater roll for this purpose being effected by the use of adjustable bearings. The bed of the trough behind the beater roll rises sharply up from the bedplate and then falls away suddenly, as shown in the diagram, forming the " backfall." When the engine is in operation the mixture of water : and pulp is drawn between the knives and circulated round the trough. The material is disintegrated into fibres of the required condition, discharged over the backfall, and kept in a state of continual circulation, and the beating maintained until the stuff has been sufficiently treated. The dimensions of the engine vary according to the capacity, which is usually expressed in terms of the amount of dry pulp the beater will hold, and the following figures may be taken as giving the average sizes : — - 2 cwt. Engine. 5 cwt. Engine. Length . Width . Depth (average) . Diameter of roll . 11 ft. Oin. 5 ft. 6 in. 2 ft. 3 in. 3 ft. 6 in. ^ 16ft. Oin. 8 ft. in. 2 ft. 9 in. 3 ft. 6 in. Sundry modifications in the form and arrangement of the beater have been tried from time to time. In 1869 Granville patented the substitution of a second beater roll in place of the stationary bedplate for the purpose of hastening the operation. Eepeated attempts have been made to construct a beating engine with two or more rolls, but it is evident that such a device could hardly succeed, since it would be 188 THE MANUFACTUEE OF PAPEE impossible to ensure proper adjustment of the rolls, and in that case one roll might be doing all the work. The first machine of this type was patented in 1872 by Salt. Similar beaters were devised by Forbes in 1880, Macfarlane in 1886, Pickles in 1894, who proposed to use three rolls, and Partington in 1901. Hoffman describes a beating engine which was working in America containing four rolls, as shown in the diagram. llie Um'plierston. — A notable modification of the Hollander, having an arrangement by which the two channels of the Fig. 50. — Umpherston Beateh engines are placed under one another, and one which is largely used for fibres, is the Umpherston. Several engines differing in detail, but embodying the same principle, have been built in imitation of this one. Bedplates of large working surface were first tried in England by Cooke and Hibbert, in 1878, but in practice it has been found that no serious deviations from the narrow type of plate are of much value. As a matter of fact it is held by some paper-makers that one or two knives would be sufficient if they could be relied on to keep true and in proper adjustment. THE PEOCESS OF BEATING 189 The Circulating Type of Beater. — The addition of some device for keeping the pulp in circulation apart from the action of the roll has received considerable attention. The early experiments in this direction with the Hollander led ultimately to the construction of the engine of the circulator type mentioned in class 2. Thus, in 1872, Nugent patented a special paddle to be used in the Hollander, by which the pulp in the trough of the beater was impelled towards the roll. Many other plans EiG. 51. — Section of Uniplierstoii Beating Engine. were tried for this purpose, and details can be seen in the List of Patents (see page 192). The introduction of the beaters with special means of circulating the pulp was found to be of the greatest service in the treatment of stuff like esparto and wood pulp), since these materials did not require the drastic measures neces- sary with rag pulp. In 1890 several engines of this class were being adopted, amongst which may be mentioned Hemmer's, Eeed's and Taylor's. The pulp discharged from the beater roll was drawn through an independent pipe or channel by means of an Archimedean screw, or a centrifugal pump. Stone Beater Bolls. — The substitution of stone for metal in the roll and bedplate of the engine brings about some 190 THE MANUFACTURE OP PAPEU remarkable changes in the nature of the beaten stuff. The fibre is submitted to the action of rough surfaces rather than that due to the contact of sharp edges, with the result that the disintegration is much more rapid, and produces a " wet " working pulp suitable for imitation parchments and similar papers. The latest materials used for this purpose Pig. 52. — Nugent's Beatiug Engiae with. Paddles for Circulating the Palp. ^ are basalt lava stone in Germany, and carborundum in America. Care is necessary in the manipulation of these beaters to prevent fracture of the stone parts. In the Wagg Jordan engine this danger is materially reduced by the construction of the working parts. Refi7iers. — In these engines the beater roll is a conical shaped drum carrying the knives, which revolve inside a conical shell completely lined with fixed knives. The fibres are thus cut up to the desired length, but before dis- charge from the engine they pass betw^een two circular discs, THE PROCESS OF BEATING 191 one stationary and the other revolving in a vertical position. The effect of the discs is to tear or bruise the fibres rather than to cut them. The refiner is best employed to clear or brush out the mass of pulp after a certain amount of prelimi- nary treatment in the beater, as the refiner cannot pro- duce the effects obtained by actual beating as in the Hollander. Potcer Consump- tion. — The long treatment required to thoroughly pulp a strong material demands a great amount of power. Engines differ con- siderably in their power consump- tion, and compari- sons are frequently made in terms of the power required to beat a given weight of pulp. But this is not always a true criterion of efficient work. Some types of beater are suitable for producing certain Fig. 53.— a "Tower" Beating -Engine with Centrifugal Pump for Circulating Pulp. 192 THE MANUFACTUEE OF PAPER results, and the mere substitution of a beater consuming less power is worse than useless unless it can be shown that the same effects are being obtained. The efficiency of the Hollander for the beating of rag pulp, in spite of the high power consumption, is a case in point. With this factor properly considered, the power required Fig. 54. — Working Parts of a Modern Eefining Engine. for beating becomes an interesting study. Many detailed experiments have been published from time to time, the most recent being those described by Beadle. Patents taken out in Connection with Beating Engines. 1855. Park (1170). — A small-steam engine was" attached to the shaft of the beater roll, so that it could be driven direct. BEATING ENGINES 193 1856. KiNGSLAND (2828). — A form of refiner in which the pulp was beaten by a vertical disc rotating in an enclosed ease. 1860. Jordan (792). — A machine devised for mixing size with pulp, made like a conical refining engine, the rubbing surface being provided with teeth or cutters. 1860. Jordan (2019). — An engine of the refiner type, constructed with a conical drum rotating in a conical casing. The knives at the larger end of the drum are placed closer together than those on the smaller end. ' 1863. Park (1138). — Two beaters placed side by side are driven by one steam engine placed between them, the operations being so timed that one rag engine is used for breaking while the other is finishing. 1864. Ibotson (2913). — The pulp is passed continuously from one engine roll to another, or from one part of a beater roll to another part of the same roll through slotted plates. 1866. KoECKNER (140). — A beating engine of the refiner type with conical drum and casing. 1866. Berham (3299). — A beating engine of the conical type with the beater roll rotating vertically instead of horizontally. 1867. Crompton (482). — Device for raising the bars in the beater roll as the edge of the plate wears away. 1867. Wood (914). — Modification in the form of the beater bars (of little importance) . 1867. Edge (3673).— The knives of the beater roll dis- tributed at equal distances apart all round the roll, alternated with strips of wood. 1869. Granville (1041). — Substitution of a second beater roll for the stationary bed-plate, the knives being set spirally round the roller. 1869. Newell (2905). — Weight of the beater roll counter- p. o 194 THE MANUFACTUEE OF PAPER poised to allow of the exact regulation of the pressure on the stuff in the beating engine. 1870. Eo«E (997). — An intercepting plate fixed to the cover of the beating engine which causes that part of the stuff which was usually carried right round by the roll to fall back behind the backfall. 1870. Bentleyand Jackson (1633) — A beater roll having the same width as the engine, and provided with a cover fitted with a pipe which conducted the material back to the front of the roll. 1871. Patton (1336). — Bottom of beating engine curved in order to prevent the stuff settling or accumulating at an}' portion of the machine. 1872. Salt (1901). — A beating engine of usual type, but having two beater rolls and two drum washers, one pair in each of the two channels. 1873. Gould (769). — A curious engine with horizontal shaft having a circular disc at the lower end, fitted with knives on the under- surface, which are in contact with fixed knives lying at the bottom of the vessel. The circulation of the pulp is effected by the centrifugal force generated. 1873. Martin (3751). — A beating engine with two rolls in the same trough, the first roll working in conjunction with a smooth surfaced beating roll, the other being in contact with a bedplate of the usual type, the object of the first roll being to partially disintegrate the material without danger of choking. 1874. Johnstone (3708). — A pulping engine in which the rubbing action of two grindstones one upon the other is utilised as a means of beating. 1876. Gardner (307). — A beating engine in which the beater roll is conical in shape, working vertically in contact with the bottom of the beating engine, which is also conical in shape, the engine itself being circular. BEATING ENGINES 10r> 1878. Cooke and Hibbert (4068). — The bedplate con- structed in the form of a circular segment with a much larger face than usual, and capable of adjustment, the beater roll itself being fixed in the bearings. 1880. Forbes (692). — A long oval shaped beating engine divided into three channels instead of two. In the two outer channels are placed beater rolls and drum washers. The stuff discharged over the backfalls from the two beat- ing engines flows down the central channel and is circulated by a special paddle constructed in such a manner as to deliver the pul]3 in two equal streams into the outer channels to each of the beater rolls. 1880. Umpherston (1150). — An engine constructed with a passage below the backfall- so that the stuff circulates in a trough underneath the beater roll, the object being to ensure more effective treatment and to save floor space. 1883. AiTCHisoN (5381). — A beating engine of usual form, but with the beater roll made conical in shape with the larger circumference outwards, and the bedplate placed on an incline parallel with the knives on the beater roll. 1884. Mayfield (2028).— The backfall of the beating engine is of entirely different construction to the ordinary machine, for the purpose of improving the circulation. 1884. HoYT (11177). — An engine resembling the Um- pherston, but with a larger roll, the diameter of which is equal to the full depth of the engine, the backfall being in a line with the axis of the beater roll. 1885. Jordan (7156). — Additions to the Jordan engine for admitting water and steam to the engine as required. 1885. KoRSCHiLGEN (9433). — The beater roll made of stone or of metal with a stone casing furnished with ribs or knives placed close together. 1886. Hibbert (4237). — A beating engine fitted with an ordinary beater roll, and having in addition a heavy disc o2 196 THE MANUFACTUEE OF PAPER rotating vertically, the disc being fitted with knives on one surface which rotate in contact with knives fixed on a stationary disc. 1886. Kron (9885). — A device for securing better circula- tion of the pulp, the stuff leaving the beater roll being divided into two streams which are brought together again in front of the roll. 1886. HoRNE (10237). — A long rectangular vessel with a large beater roll at one end, contrived so as to force the pulp leaving the beater roll to pass down a partition separating it from the pulp going towards the beater roll. 1886. Macfarlane (11084). — An engine fitted with two beater rolls which rotate in opposite directions, the stuff being mixed between them. 1887. Nacke (746). — A centrifugal circulating wheel rotating horizontally in the centre of the beating engine is used in combination with a parallel cutting disc. 1887. Marshall (1808).^ — A conical refiner having in addition at its large end a pair of grinding discs fitted with knives and rotating vertically. 1887. VoiTH (6174). — An alteration to the covers of the beater rolls which prevent stuff from being carried round the cylinder, and cause it to pass over the backfall freely. 1890. Hemmer (17483). — A beating engine provided with a separate return channel for the pulp, the circulation through the channel being effected by a small centrifugal pump. 1890. A. E. Eeed (19107).— a beating engine in which the pulp discharged over the backfall is delivered to the front of the beater roll by a screw propeller. 1891. Karger (11564). — A beater similar to the Umpher- ston, but provided with a circulating roll fitted with radial projections which delivers the stuff to the front of the beater roll. BEATING ENGINES 197 1892. Taylor (7397). — A beating engine in which the beater roll operates in a closed chamber above the vat full of pulp, the stuff being continually circulated by a centri- fugal pump which draws the stock from the bottom of the vat and delivers it to the beater roll. 1892. Annandale (9173). — A conical- shaped beating engine with the beater roll rotating in a vertical position, the larger end of the cone being downwards. 1892. Umpherston (15766). — An addition to the beating engine arranged so that two fixed bedplates are used instead of one. 1892. Miller (15947). — A machine in which two fixed bedplates are used, one below the beater roll and one above, the engine being fitted with suitable bafHe plates to ensure proper circulation. 1893. Pearson and Bertram (11956). — A special form of refining engine in which the pulp is subjected to the action of discs rotating vertically, the knives being arranged radially on the disc. 1893. Caldwell (15332). — A rotary beating engine in which the beating surfaces admit of accurate adjustment. 1894. CoRNETT (945). — An outlet is fixed to the beater roll casing close to the discharge from the bedplate, so that the roll is not impeded by the weight of the pulp, which is subsequently pumped to the front of the beater roll. 1894. Shand AND Bertram (4136). — A beating engine similiar to the Umpherston beater in which the beater roll is raised up out of the pulp and the circulation effected by means of a worm which delivers the pulp to the front of the beater roll. 1894. Pickles (20255). — A beating engine somewhat similar to an Umpherston, but fitted with three beater rolls and bedplates. 1894, Hibrert (25040) .^A beating engine in which the 198 THE MANUFACTUEE OF PAPEE pulp is beaten between two discs rotating vertically, the pulp being brought between the discs through the hollow shaft of one of the discs. 1895. Brown (1615). — An engine in which the beater roll and bedplate both revolve, but in opposite directions, and at different speeds in order to draw out the fibres. 1895. Schmidt (24730). — A device by means of which the pulp discharged from the beater roll is diverted into supple- mentary channels on either side which come together again in front of the beater roll. 1900. Hadfield (2468). — An adjustable baffie board passing through the cover of the beater roll which prevents the pulp being carried round by the roll, more or less. 1900. Masson and Scott (5367). — An improved form of Taylor beating engine in which the chest of the engine is vertical instead of horizontal. 1901. Partington (24654). — A continuous elliptical trough provided with two beater rolls. 1902. PiCARD (19635).^ — Improvements in the form of the propellers used for circulating the material. 1902. Pope and Mullen (22089). — Iniprovements in propellers for circulating the pulp. 1903. Annandale (26012). — A new form of beating engine somewhat on the principle of a steam turbine. 1905. Bertram (1727). — A beater similar to Masson's tower beater, but in which a pair of reciprocating wheels fitted with projecting knives are used instead of a centrifugal pump. 1907. Wagg's Jordan Engine (6788). — A conical refiner fitted with specially arranged metal or stone knives. CHAPTER X THE DYEING AND COLOURING OF PAPER PULP Nearly all papers, even those commonly regarded as white, are dyed with some j)roportion of colouring matter. With the ordinary writing and printing papers the process is usually confined to the addition of small quantities of pigments or soluble colours sufficient to tone the pulp and correct the yellow tint which the raw material possesses even after bleaching. In the case of cover papers, tissues, and similar coloured papers, the process is one of dyeing as it is generally understood. The colouring matters which have been employed by the paper-maker are — Pigments. (A) Added to the pulp in the form of mineral in a finely divided state. Yelloic. — This colour is obtained by the use of ochres, which are natural earth colours of varying shades, from bright yellow to brown. Red. — Ordinary red lead. Various oxides of iron, such as Indian red, Venetian red, red ochre, rouge. Blue. — Smalts — An expensive pigment prepared by grind- ing cobalt glass. TJltramarine — A substance of complex composition prepared by heating a mixture of china clay, carbonate of soda, sulphate of soda, sulphur, 200 THE MANUFACTUEE OF PAPEE charcoal, and sometimes quartz, rosin and in- fusorial earth. Prussian Blue — A compound prepared by adding potassium ferrocyanide to a solution of ferrous sulphate. Brown. — Natural earth colours, such as sienna, umber, Vandyke brown. Black. — Lamp-black, bone-black, Frankfort black. (B) Produced by the reaction of soluble salts upon one another when added to the pulp in the beating engine. Yelloiu. — Chrome Yellow — The paper pulp is first im- pregnated with acetate of lead, and potassium or sodium bichromate added. This precipitates the chromate of lead as a yellow pigment. Chrome Orange — The addition of caustic alkali to the bichromate solution converts the chrome yellow into an orange. Blue. — Prussian Blue — The paper pulp impregnated with iron salts is treated with potassium ferrocyanide. The blue colour is at once obtained. Brotvn. — Iron Buff — A light yellow-brown colour due to the precipitation of ferrous sulphate by means of an alkali. Bronze. — Manganese chloride followed by caustic soda. Soluble Colours. (A) Natural Dyes. These colouring matters are now seldom used. Yelloiv and Brown. — The vegetable extracts, such as fustic, quercitron, cutch, turmeric, have practically all been replaced by aniline colours. Red. — Madder (Turkey red), Brazilwood, cochineal (a dye obtained from dried cochineal insects). Safflower, TBE DYEING AND CODOUEING OF PAPER PULP 201 Black. — Logwood, used in conjunction with an iron salt. Cutch, used with an iron salt. (B) Coal Tar Dyes. The dyeing and colouring of paper pulp by means of the artificial organic substances has become a matter of daily routine, the expensive natural dyes and the ordinary pigments having been almost completely superseded. The numerous colouring matters available may be classified either by reference to their chemical constitution or simply on general lines, having regard to certain broad distinctions. If the latter classification is taken, then the dyes familiar to the paper-maker may be divided into — {a) Acid dyes, so called because the full effect of the colouring matter is best obtained in a bath showing an acid reaction. Q)) Basic dyes, so called because the colour is best developed in an alkaline solution, without any excess of mordant. (c) Substantive dyes, which do not require the use of a mordant, as the colour is fixed by the fibre without such reagents. Some of the most frequently used colouring matters are shown in the accompanying table on page 202. The distinction between acid and basic dye-stuffs is largely due to certain characteristics possessed by many of them. Thus magenta, which is the salt of the base known as Eosaniline, belonging to the basic colouring matters, a group of dyes which do not possess the fastness of colour peculiar to acid dyes, has a limited application. But by treatment with sulphuric acid magenta is converted into an acid magenta, and this dye has wider application than the basic salt. Similarly the basic dye called aniline blue is insoluble in water, and therefore has only a limited use, but by treat- ment with sulphuric acid it is converted into alkali blue, 202 THE MANUFACTUEE OP PAPER soluble blue and so on, which dissolve readily in water and are good fast colours. The acid dyes generally have a weaker colouring power than the basic dyes, but they produce very even shades. The difference in the composition of the basic and acid dyes is taken advantage of in the dyeing of paper pulp to secure a complete distribution of the colouring matter upon Colour. Acid. Basic. Substantive. Yellow Metanil ^^ellow. Auramine. Cotton yellow. and Paper yellow. Chrysoidine. Chrysopbenine. Orange. Orange II. Napbthol yellow S. Quinoline yellow. Red. Fast red A. Rhodamine. Congo red. Cotton scarlet. Paper scarlet. Benzopurpurin. Erythrine. Safranine. Oxamine red. Ponceau. Magenta. Blue Water blue 1 N. Methylene blue. Azo blue. and Fast blue. Victoria blue. Violet. Acid violet. New blue. Indoine blue. Metbyl violet. Crystal violet. Brown Naplitbylaniine brown. Bismarck brown. Vesuvine. Black Nigrosine. Brilliant black B. Coal Black B. ^ Green Diamond green. Malacbite green. the pulp, with the result that the intensity of colour is increased, its fastness strengthened, and the process of dyeing generally rendered more economical. This is effected by the judicious addition of a suitable acid dye to the pulp already coloured with the basic dye. The direct colouring matters have but a very limited application for paper dyeing owing to their sensitiveness to acids and alkalies. THE DYEING AND COLOURING OF PAPER PULP 203 In the colouring of paper pulp, attention is given to many important details, such as : — Fading of Colour. — Some loss of colour almost invariably occurs even with dyes generally looked upon as fast to light. The shade or tint of the paper is affected not only by exposure to light, but by contact of the coloured paper with common boards on which it is often pasted. The alkalinity of straw boards, for example, is frequently one source of serious alteration of colour, and the acidity of badly made pastes and adhesives another. In all such cases, the dyes must be carefully selected in order to obtain a coloured paper which will show a minimum alteration in tint by exposure to light or by contact with chemical substances. This is particularly necessary in coloured wrapping paper used for soap, tea, cotton yarn, and similar goods. Unevenness of Colour. — The different affinity of the various paper-making fibres for dyes is apt to produce an uneven colour in the finished paper. This is very notice- able in mixtures of chemical wood pulp or cellulose and mechanical wood pulp. The lignocellulose of the latter has a great affinity for basic dyes, and if the required amount of dye is added to a beater containing the mixed pulps in an insufficiently diluted form, the mechanical wood pulp becomes more deejDly coloured than the cellulose. If the former is a finely ground pulp, the effect is not very notice- able, but if it is coarse, containing a large number of coarse fibres, then the paper appears mottled. The defect is still further aggravated when the paper is calendered, especially if calendered in a damp condition. In that case the strongly coloured fibres of mechanical wood are very prominent. When dyes have been carelessly dissolved and added to the beating engine without being properly strained, 204 THE MANUFACTURE OF PAPER unevenness of colour may often be traced to the presence of undissolved particles of dye. Irregular Colour of the two Sides. — Many papers exhibit a marked difference in the colour of the two sides. When heavy pigments are employed as the colouring medium, tbe under side of the sheet, that is, the side of the paper in contact with the machine wire, is often darker than the top side. The suction of the vacuum boxes is the main cause of this defect, though the amount of water flowing on to the wire, the " shake " of tbe wire, and the extent to which the paper is sized are all contributory causes. By careful regulation of these varying conditions the trouble is considerably minimised. The under surface of the paper is not invariably darker than the top surface. With pigments of less specific gravity the reverse is found to be the case. This is probably to be explained by the fact that some of the colouring matter from the under side is drawn away from the paper by the suction boxes, and the pigment on the top side is not drawn away to any serious extent, because the layer of pulp below it acts as a filter and promotes a retention of colour on the top side. It is interesting to notice that this irregularity sometimes occurs with soluble dyes, as for example in the case of auramine. The decomposition of this dye when heated to the temperature of boiling water is well known, and the contact of a damp sheet of paper coloured by auramine with the surfaces of steam-heated cylinders at a high temperature brings about a partial decomposition of the dye on one side of the paper. Generally speaking, acid dyes are more sensitive to heat than basic dyes. The presence of china clay in a coloured paper is also an explanation of this irregular appearance of the two sides. China clay readily forms an insoluble lake w^itli basic THE DYEING AND COLOUEING OF PAPER PULP 205 dyes, and when the suction boxes on the machine are worked with a high vacuum the paper is apt to be more deeply coloured one side than another. The Machine Backwater. — Economy in the use of dyes to avoid a loss of the colouring matter in the " backwater," or waste water from the paper machine, is only obtained by careful attention to details of manufacture on the one hand and by a knowledge of the chemistry of dyeing on the other. The loss is partly avoided by regulating the amount of water used on the machine, so that very little actually goes to waste, and further reduced by ensuring as complete a precipitation of the soluble dye as possible. The acid dyes generally do not give a colourless back- water, and all pulps require to be heavily sized when acid dyes are used. The basic dyes are more readily precipitated than the acid dyes, particularly if a suitable mordant is used, even with heavily coloured papers. The addition of an acid dye to pulp first coloured with a basic dye is frequently resorted to as a means of more complete precipitation. Dyeing to Sample. — The matching of colours has been greatly simplified through the publication of pattern books by the firms who manufacture dyes, in which books full details as to the composition of the paper, the proportion of colour and the conditions for maximum effects are fully set out. The precise results obtained by treating paper pulp with definite proportions of a certain dye, or a mixture of several dyes, is determined by experimental trials. A definite quantity of moist partially beaten and sized pulp, containing a known weight of air-dry fibre, is mixed with a suitable volume of water at a temperature of 80^ to 90^ F. and the dye-stuff added from a burette in the form of a 1 per cent, solution. If preferred a measured volume of a 1 per cent, solution of the dye can be placed in a mortar, 206 THE MANUFAGTUEE OF PAPER and the moist pulp, previously squeezed out by hand, added gradually and well triturated with the pestle. The dyed mixture is then suitably diluted with water, made up into small sheets of paper on a hand mould or a siphon mould, and dried. The effect of small additions of colour to the contents of a beating engine is frequently examined in a rough and ready way by the beaterman, who pours a small quantity of the diluted pulp on the edge of the machine wire while the machine is running. This gives a little rough sheet of paper very quickly. The comparison of the colour of a beaterfull of pulp with the sample paper which it is desired to match is also effected by reducing a portion of the paper to the condition of pulp, so that a handful of the latter can be compared with a quantity of pulp from the engine. This is not always a reliable process, especially with papers coloured by dyes which are sensitive to the heat of the paper machine drying cylinders. Detection of Colours in Papers. — The examination of coloured papers for the purpose of determining what dyes have been employed is a difficult task. With white papers which have been merely toned the proportion of dye is exceedingly small, and a large bulk of paper has to be treated with suitable solvents in order to obtain an extract containing sufficient dye for investigation. With coloured papers dyed by means of pigments, the colour of the ash left on ignition is some guide to the substance used, a red ash indicating iron oxide, a yellow ash chromate of lead, and so on. With papers dyed by means of coal tar colours the nature of the colouring matter may be determined by the methods of analysis employed for the examination of textile fibres. THE DYEING AND COLOUEING OF PAPER PULP 207 The following hints given by Kollmann will be found useful : — Tear up small about 100 grammes of paper, and boil it in alcohol, in a flask or a reflux condenser. This must be done before the stripping with water, so as to extract the size which would otherwise protect the dye from the water. Of course the alcohol treatment is omitted with unsized paper. The paper is now boiled with from three to five lots of water, taking each time only just enough to cover the paper. This is done in the same flask after pouring oif any alcohol that may have been used, and also with the reflux condenser. The watery extract is mixed with the alcohol extract (if any). Three cases may occur: — (1) The dye is entirely stripped, or very nearly so. (2) The dye is partly stripped, what remains on the fibres showing the same colour as at first or not. (3) The dye is not stripped. To make sure of this the solution is filtered, as the presence in it of minute fragments of fibre deceive the eye as to the stripping action. In the first two cases the mixed solutions are evaporated down to one half on the water bath, filtered, evaporated further, and then precipitated by saturating it with common salt. The dye is thrown out at once, or after a time. It may precipitate slowly without any salt. The precipitated dye is filtered off and dried. To see whether it is a single dye or a mixture, make a not too dark solution of a little of it in water, and hang up a strip of filter paper so that it is partly immersed in the solution. If the latter contains more than one dye they will usually be absorbed to different heights, so that the strip will show bands of different colours crossing it. If it is found that there is only one dye, dissolve some of it in as little water as possible, and mix it with " tannin-reagent," which is made by dissolving equal weights of tannin and sodium acetate in ten times the weight of either of water. If there is a 208 THE MANUFACTUEE OF PAPER precipitate there is a basic dye, if not, an acid dye. In the former case mix the strong solution of the dye with con- centrated hydrochloric acid and zinc dust, and boil till the colour is destroyed. Then neutralise exactly with caustic soda, filter, and put a drop of the filtrate on to white filter paper. If the original colour soon reappears on drying, we draw the following conclusions : — (a) The colour is red ; the dye is an oxazine, thiazine, azine, or acridine dye, e.g., safranine. (b) It is orange or yellow ; the dye is as in (a), e.g., phosphine. (c) It is green; the dye is as in (a), e.g., azine green, (d) It is blue ; the dye is as in {(i), e.g., Nile blue, new blue, fast blue, or methylene blue, (e) It is violet ; the dye is as in (a), e.g., mauveine. If the original colour does not reappear on drying, but does so if padded with a 1 per cent, solution of chromic acid, we draw the following conclusions ; — (a) The colour is red ; the dye is rhodamine or f uchsine, or one of their allies, (h) It is green ; the dye is malachite green, brilliant green, or one of their allies, (c) It is blue ; the dye is night blue, Victoria blue, or one of their allies. (d) It is violet ; the dye is methyl violet, crystal violet, or one of their allies. If the original colour does not reappear even with chromic acid, it was in most cases a yellow or a brown, referable to auramine, chrysoidine, Bismarck brown, thioflavine, or one of their allies. If the tannin reagent produces no precipitate, reduce with hydrochloric acid and zinc, or ammonia and zinc, and neutralise and filter as in the case of a basic dye. The solution when dropped on to white filter paper may be bleached (a), may have become a brownish red (b), may have been imperfectly and slowly bleached (c), or may have undergone no change (d). (a) If the colour quickly returns the dye is azurine, THE DYEING AND COLOUEING OF PAPEE PULP 209 indigo-carmine, nigrosine, or one of their allies. If it returns only on padding with a 1 per cent, solution of chromic acid, warming, and holding over ammonia, some of the dye is dissolved in water mixed with concentrated hydrochloric acid, and shaken up with ether. If the ether takes up the dye, we have aurine, eosine, erythrine, phloxine, erythrosine, or one of their allies. If it does not, we have acid fuchsine, acid green, fast green, water blue, patent blue, or one of their allies. If the colour never returns, heat some of the dye on platinum foil. If it deflagrates with coloured fumes, the dye is aurantia, naphthol yellow S., brilliant yellow, or one of their allies. If it does not deflagrate, or very slightly, dissolve a little of the dye in one hundred times its weight of water, and dye a cotton skein in it at the boil for about fifteen minutes. Then rinse and soap the skein vigorously. If the dyeing is fast with this treatment we have a substantive cotton yellow or thiazine red ; if it is not, we have an ordinary azo dye. (b) The dye is an oxyketone, such as alizarine. (c) The dye is thiazol yellow, or one of its allies, (d) The dye is thioflavine S., quinoline yellow, or one of their allies. If the dye is not stripped by alcohol and water, it is either inorganic or an adjective dye, such as logwood black, cutch, fustic, etc. ; and we proceed according to the colour as follows : — If it is red or brown, the dyed fibre is dried and divided into two parts. One is boiled with bleaching powder. If it is bleached entirely or to a large extent, the dye is cutch. If the bleach has no action, incinerate some of the dyed fibre in an iron crucible and heat the ash on charcoal before the blowpipe. If a globule of lead is formed, we have saturn red. The second portion is boiled with concentrated hydrochloric acid. If there is no action, we have Cologne p. p 210 THE MANUFACTUEE OF PAPER umber ; if there is partial action, we have real umber ; if the dye dissolves completely to a yellow solution, we have an ochre ; if the solution is colourless instead of yellow, and chlorine is evolved during solution, we have manganese brown. If the colour is yellow or orange, boil with concentrated hydrochloric acid. If we get a green solution and a white residue, we infer chrome yellow or orange. If we get a yellow solution, we boil it with a drop or two of nitric acid and then add some ammonium sulphocyanide. A red colour shows an ochre or Sienna earth. If the colour is green, boil with caustic soda lye. If the fibre turns brown, we have chrome green. If no change takes place, boil with concentrated hydrochloric acid. A yellow solution shows green earth ; a red colour logwood plus fustic. If the colour is blue or violet, boil with caustic soda lye. If the fibre turns brown, we have Prussian blue. If no change takes place, boil with concentrated hydrochloric acid. A yellow solution shows smalts. If the colour is destroyed, and the smell of rotten eggs is developed, we have ultramarine. If the colour is black, warm with concentrated hydro- chloric acid containing a little tin salt. If the black is unchanged, we have a black pigment. If we get a pink to deep red solution we have logwood black. By means of the tests above detailed at length the group to which the dye belongs is discovered, and often the actual dye itself. Once the group is known it is generally easy, by means of the special reactions given in many books, e.g., in Schultz and Julius's " Tabellarische Ubersicht," to identify the particular dye. When one has to deal with a single dye and simply desires to determine its group, the following table, due to THE DYEING AND COLOURING OF PAPER PULP 211 J. Herzfeld, will suffice. Originally intended for textiles, it will serve, with some modifications here made in it, for the rapid testing of paper. 1. — Ebd and Keddish Brown Dyes. Boil the paper with a mixture of alcohol and sulphate of alumina. If no dye is extracted or a fluorescent solution is formed, we have an inorganic pigment, or eosine, phloxine^, rhodamine, safranine, or one of their allies. Add bleaching powder solution, and heat. If the paper is bleached, add concentrated hydrochloric acid. A violet colour shows safranine or an analogue. If there is no colour, but the fluorescence disappears, we have eosine, phloxine, rhoda- mine, or one of their allies. If the paper is not bleached test for inorganic colouring matters. Cutch brown is partly but not entirely bleached. If the alumina solution gives a red or yellow solution without fluorescence, add to it concentrated sodium bisul- phite. If bleaching takes place, heat a piece of the paper with dilute spirit. A red extract shows sandal wood, fuch- sine, etc. If there is little or no extract, we have acid fuchsine or one of its allies. If the bisulphite causes no bleaching, boil a piece of the paper with very dilute hydro- chloric acid. If the colour is unchanged, heat another piece of the paper with dilute acetate of lead. If no change takes, place, we have an azo dye. If the colour turns to a dark brownish red, we have cochineal or the like. If the boiling with very dilute hydrochloric acid darkens the colour we have a substantive cotton dye. 2. — Yellow and Orange Dyes. Heat some of the paper with a not too dilute solution of tin salt in hydrochloric acid. If the colour is unchanged, p2 212 THE MANUFACTUEE OF PAPEE with a colourless or yellow solution, boil some more paper with milk of lime. A change to reddish or brown shows turmeric or a congener. Absence of change shows phosphine, quinoline yellow, or a natural dye-stuff. If the acid tin solution turns the paper red, and then quickly bleaches it to a pale yellow, we have fast yellow, orange IV., metanil yellow, brilliant yellow, or the like. If the tin turns the paper greyish, heat another portion with ammonium sulphide. A blackening shows a lead or iron yellow. If there is no change, we have naphthol yellow, auramine, azoflavine, orange II., chrysoidine, or one of their allies. 3. — Green Dyes. Heat a sample of the paper in dilute spirit. If the spirit acquires no colour, warm for a short time with dilute sul- phuric acid. If both paper and solution become brownish red, we have logwood plus fustic. If this fails, boil with concentrated hydrochloric acid. A yellow solution shows green earth. If this fails, boil with concentrated caustic soda. Browning shows chrome green. If the spirit becomes blue, it is a case of paper which has been topped with blue on a yellow, brown, or green ground. The solu- tion and the insoluble part are separately tested. The case is probably one of an aniline blue dyed over a mineral pigment. If the spirit becomes green, heat with dilute hydrochloric acid. If the fibre is completely or nearly bleached, and the acid turns yellow, the dye is brilliant green, malachite green, or one of their allies. 4. — Blue and Violet Dyes. Heat some of the paper with dilute spirit. If the alcohol remains colourless, we have Prussian blue or ultramarine. If it becomes blue or violet, shake some of the paper with THE DYEING AND COLOUEING OF PAPER PULP 213 concentrated sulphuric acid. A dirty olive green shows methylene blue, and a brownish colour shows spirit blue, water blue, Victoria blue, methyl violet, etc. If the spirit turns yellow, and the colour of the paper changes, we have wood blue or wood violet. r CHAPTEK XI PAPER MILL MACHINERY In the case of common printings and writings, which form the great bulk of the paper made, the possibiHty of one mill competing against another, apart from the im- portant factor of the cost of freight, coal, and labour, is almost entirely determined by the economy resulting from the introduction of modern machinery. The equipment of an up-to-date paper mill, therefore, comprises all the latest devices for the efficient handling of large quantities of raw material, the economical production of steam, and the minimum consumption of coal, matters which are of course common to most industrial operations, together with the special machinery peculiar to the manu- facture of paper. The amount of material to be handled may be seen from the table on page 215, which gives the approximate quantities for the weekly output of a common news and a good print- ing paper. Economy in Coal Consumption. — The reduction to a minimum of the amount of coal required for a ton of paper has been brought about by the use of appliances for the better and more regular combustion of the coal, such as mechanical stokers, forced and induced draught, the intro- duction of methods for utilising waste heat in flue gases by economisers, and the waste heat in exhaust steam and condensed water by feed-water heaters, the adoption of machines for securing the whole energy of the live steam PAPER MILL MACHINERY 215 by means of superheaters, adequate insulation of steam mains and pipes, high pressure boilers, and engines of most recent design. The firing of steam boilers is now conducted on scientific principles, the coal being submitted regularly to proper analysis for calorific value, the evaporative power of the boilers being determined at intervals by adequate trials, the condition of the waste flue gases being automatically Table showing the Materials required eor News AND Printings. - Common News. Good Printings. Weekly output of paper, say . 600 tons 250 tons Mechanical wood pulp, moist, 50 per cent, dry . 800 „ Nil. Chemical wood pulp, dry 200 „ 150 tons Esparto . Nil. 200 „ Soda ash . Nil. 16 „ Coal. 600 tons 800 ,, Lime Nil. 45 „ China clay 60 tons 25 ,, Bleach . Nil. 30 „ Alum, rosin, and chemicals 20 tons 20 „ Water, per ton paper 8,000 gallons 40,000 gallons recorded in order to obtain regular and maximum com- bustion. The Sarco Combustion Recorder. — This instrument is a device which automatically records the percentage of car- bonic acid gas in the waste gases from boiler furnaces. The flue gases are analysed at frequent and regular intervals, and the results of the analysis can be seen on a chart immediately, so that it is possible to determine the effect of an alteration in the firing of the boilers within two minutes of its taking place. The apparatus is rather complicated, but the principle upon which it is based is simple. 216 THE MANUFACTURE OF PAPEE Measured quantities of the flue gases are drawn into graduated glass tubes and brought into contact with strong caustic soda solution, which absorbs all the carbonic acid gas. The remaining gases not absorbed by the caustic soda are automatically mea- sured and the percentage of carbonic acid gas re- gistered on the chart. The use of suitable boiler feed-water is also an important factor in modern steam - raising plant. The hot condensed water from the paper machine drying cylinders, and exhaust steam from the engines and steam- pipes, is returned to the stoke-hole to be utilised in heating up the cold water which has been previously softened by chemical treatment. Water Softening. — The water softeners available on the market are numer- ous, and as each possesses special advantages of its own, it would be almost invidious to select any one for particular notice. They are based upon the principle of mixing chemicals with the water to be treated, so as to precipitate the matters in solution and give a boiler feed-water free from carbonates and sulphates of lime and magnesia. The chemicals are Fig. 55. — Conventional Diagram of a Water Softening Plant. A. Water supx)ly. B. Regulating tank. C. Lime mixer. D. Soda tank. E. Settling tank and filter. F. Outlet for softened water. PAPER MILL MACHINERY 217 added in the form of solutions of carefully regulated strength to the water, which flow in a continuous stream into a tank. The flow of the water and chemical reagent is adjusted by previous analysis. The various machines differ in details of construction, and in the methods by which the mixing of the water and re- agents is effected. The object to be achieved is the complete precipitation of the dissolved salts and the production of a clear water, free from sediment, in an apparatus that will treat a maximum quantity of water at a cheap rate per 1,000 gallons. The process needs proper attention. The addition of reagents in wrong proportions will do more harm than good, and possibly result in hardening the water instead of softening it. The following may be quoted as an example : — Composition of Water. Before Treatment. After Treatment. Change. Calcium carbonate . Calcium oxide (lime) Calcium silicate Calcium sulphate Magnesia .... Ferric oxide, etc. 13-863 00 2-062 1-625 0-0 0-447 38-920 14-300 3-591 2-121 0-266 0-987 25-057 gain 14-300 „ 1-529 „ 0-496 „ 0-266 ,, 0-540 ,, Scale forming minerals . 17-997 60-185 42-188 gain Calcium chloride Magnesium chloride Sodium chloride 1-331 0-672 0-478 2-114 0-0 0-476 0-783 gain 0-672 loss 0-003 „ Soluble salts . . . 2-482 2-590 0-108 gain Total mineral matter 20-479 62-776 42-297 gain Carbonic acid gas Oxygen gas . 9-71 0-66 0-0 0-66 9--71 loss 0-0 Treatment required: 1-8 lbs. of lime, 0-2 lbs. soda ash per 1,000 gallons. Apparently 5-5 lbs. of lime were being used and no soda (Stromeyer). 218 THE MANUFACTUEE OF PAPEE Superheated Steam. — The effective application of the energy of the high pressure steam is probably one of the most important problems in paper mill economy. The use of superheated steam is being extended in every direction, and, in addition to the advantages obtained in the steam engine itself, its wider possibilities for the boiling of esparto, wood, and fibres generally have been noted. The following case may be quoted as the result of a trial at a paper mill, showing for stated conditions the advantages of superheated steam : — - Superheated Steam. Ordinary Steam. Duration of test hours . 26 34 Coal consumed (lbs.) — Per hour .... 610-5 661-5 Per 1 h.-p. hour . 1-83 , 2-08 Water evaporated (lbs.)— Per hour .... 4,832 5,679 Per 1 h.-p. hour. 14-55 17-8 Prom and at 212^ P. . 8-7 8-94 Steam, temperature P. . 464 334 Pressure .... 90-3 90-8 Steam engine — 1 h.-p. total 331-5 323-2 Temperature P. . Coal used per 1 h.-p.^ — 381-8 , ^ 333-8 Per hour at boiler 1-83 2-08 This appears to show a saving of 12 per cent. Gas Producers. — The substitution of gas for steam in the paper mill has not yet proved a success. The fact that heat is required for the drying cylinders of a paper machine, and that the heat is most cheaply and readily obtained in the form of exhaust steam from the engines driving the paper machine, militates considerably against economies which might otherwise be possible. The difficulties of heating PAPER MILL MACHINERY 219 such cylinders, or rather of properly controlling and regu- lating the temperature by any other means than steam, may easily be surmised. Gas engines of over 200 h.-p. seem to give considerable trouble at present, but no doubt in course of time the required improvements will be effected. It is generally supposed that gas producers can only be economical when utilised for the production of gas on a large scale, and for distribution to engines of smaller capacity than the main steam engine required in a paper mill. The peculiar conditions of the manufacture of paper do not appear to be favourable to the adoption of the gas producer system in its present form. Motive Power. — The paper-maker has taken advantage of every modern improvement in steam engines for the purpose of reducing the cost of motive power. Amongst other alterations in this direction the use of a high speed enclosed engine and the employment of the modern steam turbine may be noted. In the enclosed engine the working parts are boxed in by a casing fitted with oil-tight doors. The cranks and con- necting rods splash into the oil, which is thus thrown about in all directions, so as to ensure sufficient lubrication. Another feature of this engine is the variable speed, and it is possible to run the paper machine at speeds varying from 100 to 500 ft. per minute without the use of change wheels. Electrical Driving. — The application of electricity for motive power has made steady advances in the paper mill. At first it was limited to the driving of machinery in which variations of speed or load were not required to any large extent, but of recent years beating engines, calenders, and paper machines have all been fitted with electrical drives. Fig enclosed" Steam Engine. PAPEE MILL MACHINERY 221 The following details relate to the installation at the Linwood Paper Mills : — The installation consists of 250-K.W. steam dynamos. The engines are Willan's high speed triple expansion, working with a boiler pressure of 250 lbs. per square inch at the stop valve, the steam being superheated to give a temperature of 500° Fahr. at the engine. By means of jet condensers a vacuum of 25 to 25J inches is obtained on the engines. The two boilers are of the Babcock type, and have 3,580 square feet of heating surface each. The furnaces have chain grate stokers, and the boilers are arranged with their own superheaters. The motor equipment consists of eight 80, two 50, and ten 25 B.H.P. motors. Six of the 80 B.H.P. drive the beating engines, and it has been found that the motors readily respond to an overload of 50 per cent, without beating or other trouble. To remedy the excessive and sudden variation a belt drive was adopted. An 80 motor drives the pulp refining engine. The two paper-making machines have each two motors, one a 25 and a 50 and the other two 25 B.H.P. motors. The speed can be regulated with exactitude. The auxiliary plant of the paper-making machine, pumps, agitators, etc., is worked from lines of shafting driven by motors. Calender motors are of the variable speed type, being- designed to run from 100 revolutions per minute to 600 revolutions per minute. Variations from 300 to 600 revolutions per minute can be regulated by the shunts, the loss being negligible. Several of the motors are geared up to the various machines, as is the case with the calender. As regards cost, the capital outlay on the 500-K.W. generating plant, including engines, dynamos, boilers, condensers, steam pipes, filters, etc., and all engine room accessories, was £9,500. In addition to the above, the plant also contains a Parson's 222 THE MANUFACTURE OF PAPER 1 a PAPER MILL MACHINERY 223 steam turbine of 1,000 K.W., driving two continuous current dynamos. The Eihel Patent. — One of the most important improve- ments in connection with the manufacture of newspaper is the Eibel process, designed to increase the speed of the machine and to reduce the amount of suction at the vacuum box. In the ordinary machine the wire has usually been arranged to move in a horizontal plane. In some machines means have been provided for adjusting the breast-roll end of the wire to different elevations to provide for dealing with different grades of stock, but the wire has never hitherto been so inclined as to cause the paper stock to travel at a XXXX^^OOroODDDOTpOODOOGOOOOODOC Fig. 58. — Diagram of the "Eibel" Process. speed, under the action of gravity, to equal or approxi- mate the speed of the wire. In all previous methods of working, the wire has for a considerable portion of its length, starting from the breast-roll, drawn the stock along in consequence of the wire moving much faster than the stock, and the stock has waved, or rippled, badly near the breast-roll end of the wire. This has gradually diminished until an equilibrium has been established and an even surface obtained, but not until the waving or rippling has ceased at some considerable distance from the breast-roll have the fibres become laid uniformly, and the machines have there- fore necessarily been run slowly to give ample time for the water to escape and for the fibres to lie down so as to make them a uniform sheet. In many cases the breast-roll has 224 THE MANUrACTUEE OE PAPER been raised 14 or 15 inches, and the stock rushes, as it were, downhill. As, during the formation of the paper, the stock and the wire practically do not move relatively to each other, there is no drag of the stock upon the wire ; consequently there is a more rapid and uniform drainage of the water from the stock, the full influence of the " shake" is made effective to secure uniformity in the distribution and interlocking of the fibres, and the regularity of the formation of the paper is not disturbed by waves or currents, which would otherwise be caused by pull of the wire upon the stock. This ingenious device is now working successfully in many paper mills. Machinery. — In setting out the plant necessary for a paper mill which is designed to produce a given quantity of finished paper, the manufacturer takes into consideration the class of paper to be made and the raw material to be employed. The following schedule has been prepared on such a basis : — Plant and Machinery for High-class Printings. Paper. High-class printings made of wood pulp and esparto, used alone or blended in varying proportions as required. Quantity, 250 tons weekly. Baw Material. Esparto; chemical wood pulp. Quantity: esparto, about 200 tons; wood pulp, 150 to 160. China clay and usual chemicals. In the estimation of materials required for the production of about 250 tons of paper, it is assumed that the 200 tons of esparto fibre will yield 90 tons bleached esparto fibre, and PAPER MILL MACHINERY 225 that the mechanical losses which take place during manu- facture are counterbalanced by the weight of china clay added to the pulp. These conditions naturally vary in different mills, but such variations do not affect the schedule of machinery. U^iloading Sheds. 2 steam or electric cranes for handling fibre, clay, alum, bleach, rosin, coal, and finished paper. 1 3-ton weighbridge. 1 5-cwt. platform scales. Steam Plant, 6 8-ft. by 30-ft. Lancashire boilers. Fuel economiser. Feed-w^ater pump and tank. Water softening apparatus. 1 500-h.-p. main steam engine, for fibre departments and beater floor. Chemical Department. Hoist for clay, alum, bleach, lime, &c. 4 causticising pans, 9 ft. diameter, 9 ft. deep. 2 storage tanks. 2 chalk sludge filter presses. 2 clay-mixing vats, 6 ft. diameter, 6 ft. deep. 1 starch mixer, 6 ft. diameter, 6 ft. deep. 1 size boiler, 8 ft. diameter, 8 ft. deep. 3 size storage tanks, 1,000 gallons each. 3 bleach-mixing vats. 3 bleach liquor settling tanks. 2 clear bleach liquor storage tanks. 1 alum dissolving tank. Recovery Department : — • Soda. 1 multiple effect evaporating plant. 1 rotary furnace, p. 0, 226 THE MANUFAOTUEE OE PAPER 4 lixiviating tanks, 2,000 gallons each. 2 storage tanks for clear liquor from lixiviating tanks, 20,000 gallons capacity. Fibre. 2 tanks for receiving machine backwater. 2 Fullner's stuff catchers, or some other system of treating backwater. 2 filter presses. Esparto Department. 1 esparto duster. Travelling conveyer for cleaned esparto. 6 Sinclair vomiting boilers, each of 3 tons capacity. 2 measuring tanks for caustic liquor. 4 washing engines, 15 cwt. capacity. 6 Tower bleaching engines. 1 press-pate. 10 galvanised iron trucks. Wood Pulp Department. 4 pulp disintegrators and pumps. 4 Tower bleaching engines. 4 washing tanks or drainers. 6 galvanised iron trucks. Beater Floor. ^ 8 1,200-lbs. beating engines. 2 Marshall Refiners. 6 galvanised iron trucks. Paper Machine Room. 2 paper machines, 106 in. wide, with stuff chests, strainers, and engines complete. 1 paper machine, 120 in. wide, with stuff chests, strainers, and engines complete. Patent dampers for each machine. Calendering Room. 2 110-in. supercalenders. PAPER MILL MACHINERY 227 2 100-in. supercalenders. 2 6-reel cutters. 1 200-h.-p. main steam engine. Finishing Room. Sorting tables. Packing press. Weighing machine. Repairs Department. Usual repair outfit, such as lathes, planing machine, drilling tools, etc. Blacksmith's shop outfit. Carpenter's shop outfit. Calender roll grinder. Water Supply. Main storage tank, 50,000 gallons capacity. Water pumps. Piping and connections to various departments. Bell's patent filters (if necessary). Q 2 CHAPTER XII THE DETERIORATION OF PAPER Eecent complaints about the quality of paper and the rapid decay of manuscripts and papers have resulted in arousing some interest in the subject of the durability of paper used for books and legal documents, and in the equally important question of the ink employed. The Society of Arts and the Library Association in England and the Imperial Paper Testing Institute in Germany have already appointed special committees of inquiry, and from this it is evident that the subject is one of urgent importance. It is sometimes argued that the lack of durability is due to the want of care on the part of manufacturers in preserving the knowledge of paper-making as handed down by the early pioneers, but such an argument is superficial and utterly erroneous. The quality of paper, in common with the quality of many other articles of commerce, has suffered because the demand for a really good high-class material is so small. The general public has become accustomed to ask for something cheap, and since the reduction in price is only rendered possible by the use of cheap raw material and less expensive methods of manu- facture, the paper of the present day, with certain exceptions, is inferior to that of fifty years ago. The causes which favour the deterioration of paper are best understood by an inquiry into the nature of the fibres and other materials used and the methods of manufacture employed. THE DETEEIOEATION OF PAPER 229 The Fibres Used. — Cotton and linen rags stand pre- eminent amongst vegetable fibres as being the most suitable for the production of high-class paper capable of with- standing the ravages of time. This arises from the fact that cotton and linen require the least amount of chemical treatment to convert them into paper pulp, since they are almost pure cellulose, cotton containing 98*7 per cent, of air- dry cellulose, and flax 90*6 per cent. The processes through which the raw cotton and flax are passed for the manu- facture of textile goods are of the simplest character, and the rags themselves can be converted into paper without chemical treatment if necessary. As a matter of fact certain papers, such as the 0. W. S. and other drawing papers, are manufactured from rags without the aid of caustic soda, bleach, or chemicals. The rags are carefully selected, boiled for a long time in plain water, broken up and beaten into pulp, and made up into sheets by purely mechanical methods. The liability of papers to decay, in respect of the fibrous composition, is almost in direct proportion to the severity of the chemical treatment necessary to convert the raw material into cellulose, and the extent of the deviation of the fibre from pure cellulose is a measure of the degradation which is to be expected. The behaviour of the fibres towards caustic soda or any similar hydrolytic agent serves to distinguish the fibres of maximum durability from those of lesser resistance. It may be noted that in the former the raw materials, viz., cotton, linen, hemp, ramie, etc., contain a high percentage of pure cellulose, while in the latter the percentage of cellulose is very much lower, such fibres as esparto, straw, wood, bamboo, .etc., giving only 40 — 50 per cent, of cellulose. The two extremes are represented by pure cotton rag and mechanical wood pulp. Other things being equal, the decay which may 230 THE MANUFACTUEE OF PAPEE take place in papers containing the fibre only, without the admixture of size or chemicals, may be considered as one of oxidation, which takes place slowly in cotton, and much more rapidly with mechanical wood pulp. Experimental evidence of this oxidation is afforded when thin sheets of paper made from these materials are exposed to a temperature of 100° to 110° C. in an air oven. The cotton paper is but little affected, while the mechanical wood pulp paper soon falls to pieces. The order of durability of various papers in relation to the fibrous constituents may be expressed thus : (1) rag cellulose ; (2) chemical wood cellulose ; (3) esparto, straw, and bamboo celluloses; (4) mechanical wood pulp. The rate and extent of oxidation is approximately shown by the effect of heat as described. The differences between, the celluloses are also shown by heating strips of various papers in a weak solution of aniline sulphate, which has no effect on wood or rag cellulose, dyes esparto and straw a pinkish colour, and imparts a strong yellow colour to mechanical wood pulp and jute. Physical Qualities. — The permanence of a paper depends not only upon the purity of the fibrous constituents and the freedom from chemicals likely to bring aboiit deterioration, but also upon the general physical properties of the paper itself. Other things being equal, the more resistant a paper is to rough usage the longer will it last. The reason why rag papers are so permanent is that not only is the chemical condition of the cellulose of the highest order, but the physical structure of the fibre is such that the strength of the finished paper is also a maximum. The methods of manufacture may be modijied to almost any extent, giving on the one hand a paper of extraordinary toughness, or on the other hand a paper which falls to pieces after a very short time. Thus a strong bank-note THE DETEEIOEATION OF PAPER 231 paper may be crumpled up between the fingers three or four hundred times without tearing, while an imitation art paper is broken up when crumpled three or four times. A thorough study of the physical qualities of a paper is therefore necessary to an appreciation of the conditions for durability. The physical structure of the fibre, the modifi- cations produced in it by beating, the effect of drying, sizing, and glazing upon the strength and elasticity of the finished paper, are some of the factors which need to be considered. Strength. — The strength of a paper as measured by the tensile strain required to fracture a strip of given width, and the percentage of elongation which the paper undergoes when submitted to tension, are properties of the utmost import- ance. The elasticity, that is, the amount of stretch under tension, has not received the attention from paper-makers that it deserves. If two papers of equal tensile strength differ in elasticity, it may be taken for granted that the paper showing a greater percentage of elongation under tension is the better of the two. The strength of a paper, as already indicated, is greatly influenced by the conditions of manufacture. This has been explained in the chapter devoted to the subject of beating, and other examples are briefly given in the following paragraphs. Bulk. — The manufacture during recent years of light bulky papers for book production has accentuated the problem in a marked degree, and the factor of hidk as one of the causes of deterioration is therefore a comparatively new one. It is interesting to notice that the rapid destruc- tion of such books by frequent use is in no way related to the chemical purity of the cellulose of which it is composed, or to the influence of any chemical substance associated with the fibre. It is purely a mechanical question, to be explained by reference to the process of manufacture. 232 THE MANUEACTUEE OF PAPER This paper is made from esparto entirely, or from a mixture of esparto and wood pulp. The pulp is beaten quickly, and for as short a time as possible, little or no china clay being added, and only a very small percentage of rosin size. The wet sheet of paper is submitted to very light pressure at the press rolls, and the bulky nature is preserved by omitting the ordinary methods of calendering. The paper thus produced consists of fibres which are but little felted together. The physical condition and structure of the paper are readily noticeable to the eye, and when these peculiarities are reduced to numerical terms the effect of the conditions of manufacture is strikingly displayed. The effect of this special treatment is best seen by con- trasting the bulky esparto featherweight paper with the normal magazine paper made from esparto. In the latter case a smoother, heavier, stronger sheet of paper is made from identically the same raw material. But the pulp is beaten for a longer period, while mineral matter and size are added in suitable proportions. The press rolls and calenders are used to the fullest extent. The difference between these two papers, both consisting, as they do, of pure esparto with a small proportion of ash may be emphasised by comparing the analysis by height with analysis hj volume. The two papers in question when analysed by weight proved to have the following composition : — Parts by Weight. Featherweight. Ordinary. Esparto fibre Ash, etc. 96-0 4-0 100-0 95-4 4-6 100-0 THE DETERIORATION OF PAPER 233 But if the papers are compared in terms of the composition by volume, it will be found that the featherweight contains a large amount of air space. Composition by Volume. Featherweight. Ordinary. Esparto fibre Ash, etc. Air space 28-0 0-7 71-3 100-0 6o-o 1-8 32-7 100-0 In other words, the conditions of manufacture for the bulky paper are such that the fibres are as far apart from one another as possible, and the cohesion of fibre to fibre is reduced to a minimum. While paper of this description is agreeable to the printer, and probably to the general reading public, yet its strength and physical qualities, from the point of view of resistance to wear and tear, are of the lowest order. It is very difficult to rebind books made from it, which is not altogether to be wondered at, seeing that the bookbinder's stitches can hardly be expected to hold together sheets containing 60 to 70 per cent, of air space. This concrete case emphasises the necessity for including in a schedule of standards of quality a classification of papers according to strength and bulk. Surface. — The introduction of new methods of printing has brought about some changes in the process of glazing and finishing paper which are not altogether favourable to the manufacture of a sheet having maximum qualities of strength and elasticity, two conditions which are essential 234 THE MANUFACTUEE OF PAPEE to permanence. In other words, the very high finish and surface imparted to paper by plate-glazing, supercalendering, water finish, and other devices of a similar character is carried to excess. All papers are improved in strength by glazing up to a certain point, but over-glazing crushes the paper, renders it brittle and liable to crack. Unfortunately, the maximum strength of a paper is generally reached before the maximum of finish, with the result that the former is frequently sacrificed to the latter. The usual result of glazing is found in an increase of 8 to 10 per cent, in the tensile strength, but a diminution of elasticity to the extent of 8 to 10 per cent. "With supercalendered magazine papers, the high surface is imparted for the sake of the illustrations w^hich are pro- duced by methods requiring it. The addition of consider- able quantities of clay or mineral substances improves the finish, so that the question of the relation of glazing to strength, surface, and loading is one which affects the subject of deterioration of paper very materially. With writing paper the false standard of an " attractive " appear- ance is almost universally accepted by the public as the basis of purchase without any reference to actual quality. Mineral Substances. — China clay, sulphate of lime, agalite and other inert mineral substances are important factors in lowering the quality of paper, not so much in promoting the actual deterioration of paper by any chemical reaction with the fibres, as in making the paper less capable of resistance to the influence of atmospheric conditions and ordinary usage. Clay in small, well-defined quantities serves a useful purpose, if added to some papers, because it favours the production of a smooth surface, but when the combination of mineral substances is carried to an extreme, then the result from the point of view of per- manence is disastrous. This is well recognised by all THE DETEEIORATION OF PAPER 23o paper-makers, and in Germany the limits of the amount of clay or loading in high-grade paper have been rigidly fixed. In the case of imitation art paper, which contains 25 to 30 per cent, of its weight of clay, the strength and resist- ance of the sheet is reduced to a minimum. The paper falls to pieces if slightly damped, the felting power of the fibres being rendered of no effect owing to the weakening influence of excessive mineral matter. This paper is used chiefly for catalogues, programmes, circulars, and printed matter of a temporary and evanescent character, and so long as it is confined to such objects it serves a useful pur- pose, being cheap, and suitable for the production of illustrations by means of the half-tone process ; but its lasting qualities are of the lowest order. The addition of 10 per cent, of any mineral substance must be regarded as the maxhnum allowance for papers intended for permanent and frequent use. Coati7ig Material. — The ingenious method for producing an absolutely even surface on paper by the use of a mix- ture of clay or other mineral substance and an adhesive like glue or casein brushed on to the surface of the paper, is responsible for many of the complaints about the papers of the present day. The sole merit of this substance is the facility with which half-tone process blocks can be utilised for the purpose of picture production. Beyond this, nothing can be said. The paper is brittle, susceptible to the least suspicion of dampness, with a high polish which in artificial light pro- duces fatigue of the reader's eye very quickly, heavy to handle, and liable to fall to pieces when bound up in book form. As the fibrous material is completely covered by mineral substances, it is frequently considered of secondary import- ance, with the result that the ''value" of the paper is 236 THE MANUFACTUEE OF PAPER judged entirely by the surface coating, with little regard to the nature of the body paper. In such cases, with an inferior body paper, the pages of a book very quickly discolour, and the letterpress becomes blurred. Analysis of a Typical Art Paper. - Per Cent, by Weight. - Volume Composition per Cent. Fibre 77-5 Fibre . 68-3 Ash, etc. . 22-5 Ash 12-0 Air space 19-7 100-0 100-0 Rosin. — The presence of an excess of rosin is a well- known factor in the disintegration of the paper, even when the fibrous composition is of the highest order. The decomposition is largely due to the action of light, many experiments having been made by Herzberg and others to determine the nature of the reactions taking place. One of the chief alterations is the change brought about in the ink-resisting qualities of the paper. The actual character of the chemical reactions as far as the effect on the fibre is concerned is not accurately known. The degradation of a hard-sized rosin paper by exposure to strong sunlight, for example, is probably due to the alteration in the rosin size, and not to any material change in the cellulose. It is hardly conceivable that in a pure rag paper sized with rosin and yielding readily to ink penetration, after about one year's exposure to light, the cellulose itself had undergone any chemical changes capable of detection. THE DETEEIOEATION OF PAPEE 237 Gelatine. — Papers properly sized with gelatine are prefer- able to those sized with rosin for the majority of books and documents preserved under normal circumstances. But the nature of a tub-sized paper may be, and often is, greatly altered by unusual climatic conditions. In hot, damp countries papers are quickly ruined, and high-class drawing papers sized with gelatine often rendered useless. The change is scarcely visible on the clean paper, and is only observed when the paper is used for water-colour work, the colour appearing blotchy in various parts of the sheet where the gelatine has been decomposed by the' united action of heat and damp. The artist is frequently compelled in such cases to put a layer of heavy white colour on the sheet of paper before proceeding to paint the picture. The storage of books under favourable conditions has a great deal to do with the permanence of the paper, and the degradation of a paper in relation to the tub-sizing qualities is much hastened by the presence of moisture in the air. Starch. — The same is true of starch, which is largely employed as a binding or sizing material in paper. The degradation of gelatine, starch, and similar nitrogenous substances is due to the action of organisms, and the following experiments, suggested by Cross, are interesting in this connection. If strips of paper are put into stoppered bottles with a small quantity of warm water and kept at a temperature of about 80° F., fungus growths will be noticed on some of them after the lapse of fourteen days. Kag papers sized with gelatine will show micro-organisms of all kinds. A pure cellulose paper, like filter paper, will not produce any such effects. The result in the first case is due to the nitrogenous substance, viz., the gelatine used in sizing, 238 THE MANUEACTUEE OE PAPER since the two papers are identical as far as the cellulose fibres are concerned. High-class wood pulp papers, unless sized with gelatine, would not show similar results. The action of the organisms upon the nitrogenous material by a process of hydrolysis is in the direction of the production of soluble compounds allied to the starch sugars capable of being assimilated by organisms. The cellulose of esparto and straw are readily attacked, and it is on this account that the tissues of the various straws are digested more or less when eaten by animals. It is for this reason that the celluloses from straw and esparto are inferior to the cotton cellulose in producing a paper likely to be permanent. Chemical Residues,- — The necessity for manufacturing a pure cellulose half-stuff is fully recognised by paper- makers. This was not the case in the early days of the manufacture of wood pulp, for it is a matter of common experience that many of the books printed on wood pulp paper between 1870 and 1880 are in a hopeless condition, and it is quite easy to find books and periodicals of that date the pages of which crumble to dust when handled. This serious defect has been proved to be due to the pre- sence of traces of chemicals used in manufacture which have not been thoroughly removed from the pulp. The precautions necessary in bleaching pulp by means of chloride of lime, in order to prevent (1) any action between the fibre and the calcium hypochlorite, ;2) the presence of residual chlorine or soluble compounds derived from it, and (3) the presence of by-products arising from the use of an antichlor, are also well known to paper makers. The subject has been closely studied by chemists, who have shown that the deterioration of many modern papers may be ascribed to carelessness in bleaching. The questions relating to the chemical residues of paper THE DETERIOEATION OF PAPER 239 can only be adequately dealt with by a discussion of actual cases which arise from time to time. There are certain conditions in manufacture, common to all papers, which may give rise to the presence of chemical residues, of which two have already been mentioned. The acidity of papers is frequently quoted as an instance. It is true that the presence of free acid in a paper is most undesirable, as it seriously attacks the cellulose, converting it into an oxidised form. This in course of time renders the paper so brittle as to destroy its fibrous character. The change is brought about by the acid, which itself suffers no material alteration, so that the process of deterio- ration is continued almost indefinitely until the cellulose is completely oxidised. Most papers, however, show an acid reaction when tested with litmus, the usual reagent employed by those not familiar with the proper methods of testing paper. All papers which have been treated with an excess of alum for sizing purposes would show an acid reaction with litmus without necessarily containing any free acid. The presence of iron is undesirable, particularly in photo- graphic papers, and since cellulose has a remarkable affinity for iron, the conditions of manufacture which tend to leave iron in the pulp have to be taken into consideration. The presence of minute quantities of iron in the form of impurities must not be confused with the presence of iron in large quantities derived from the toning and colouring of paper by means of iron salts. The fading of colour is frequently observed when coloured papers are tested on boxboards, particularly those made of straw. This fading may often be traced to the presence of alkali in the straw board which has not been completely removed in the process of manufacture. The blurring of letterpress is a defect which often occurs with printing papers made of chemical wood pulp. The oil 240 THE MANUFACTUEE OF PAPEE in the ink seems to separate out on either side of the letter, producing a discoloration. In such cases the paper itself frequently exhibits an unpleasant smell. These defects are usually determined hy the presence of traces of sulphur compounds in the paper resulting from incomplete washing of the pulp in manufacture. The presence of sulphur compounds sometimes associates itself with papers which have been coloured by means of ultra- marine, which in presence of alum is slightly decomposed by the heat of the drying cylinders. Some knowledge of the effect of chemical residues in paper is important, not only in regard to the deterioration which takes place in the fibre itself, but also in relation to the fading of the ink which is used. The subject of the ink has received much attention from chemists on account of the serious difficulties which have been experienced by State departments in various countries. The United States Department of Agriculture have devised certain methods for ascertaining the suitability of stamping ink used by the Government and suggest the qualities desirable in such an ink. The ink, first of all, must produce an indelible cancellation; that is, it must be relatively indelible as compared with the ink used for printing the postage stamps. The post-mark made with the ink must dry quickly in order that the mail matter may be handled immediately without any blurring or smearing of the post- mark. Both this property and the property of the indelibility involve the question of the rate at which the ink penetrates or is absorbed by the fibre of the paper. A satisfactory ink does not harden or form a crust on the ink-pad on exposure to air. There must be no deposition of solid matter on the bottom of the vessel in which the ink is stored, and the pig- ments on which the indelibility of the ink depends, if THE DETERIORATION OF PAPER 241 insoluble, must not settle out in such a way as to make it possible to pour off from the top of the container a portion of the ink which contains little or none of the insoluble pigment or pigments. Colour. — If the subject of deterioration of paper is to be considered in its broadest sense as including changes of any kind, the fading of colour must be taken into account. The use of aniline dyes which are not fast to light results in a loss of colour in paper just as with textiles, and the fading may be regarded as a function of the dye and not as arising from its combination with the paper. The gradual fading of some dyes, however, and of many water-colour pigments may be traced to the presence of residual chemicals in the paper and to the presence of moisture in an atmosphere impregnated with gaseous or suspended impurities. In fact the latter is a greater enemy to permanence of colour than light, since it has been proved by experiment that most colours do not fade when exposed to light in a vacuum. The oxygen of the air in combination with the moisture present is the principal agent in bringing about such changes. The dulling of bronze, or imitation gold leaf, on cover papers is a practical illustration of this, though this can hardly be quoted as an instance of actual deterioration of the paper. The maintenance of the original colour can only be assured by the careful selection of pure fibrous material, the use of fast dyes, and the preservation of the book or painting from the conditions which favour the fading as described above. For common papers such precautions become impossible, but for water-colour drawings and valuable papers they are essential. The demand for an abnormally white paper is indirectly the cause of deterioration in colour, but in this case the ultimate effect is not a fading but a discoloration of white p. R 242 THE MANUFACTUEE OE PAPER to a more or less distinct yellow or brown colour, due to changes in the fibre which may often be traced to excessive bleaching. In this case the fading of colour is directly due to deterioration of the paper itself, and may occur in celluloses of the best type. With lower-grade papers con- taining mechanical wood pulp the degradation of colour and fibre is inevitable. Air and Moisture. — The exact effects produced on paper freely exposed, or in books as ordinarily stored, depend upon the condition of the atmosphere. Pure air has little or no action upon paper, cellulose being a remarkably inert sub- stance, and even in impure mechanical wood pulp, if merely exposed to pure dry air, the signs of decay would be delayed considerably. The combined action of air and moisture is of a more vigorous character in promoting oxidation changes in the fibres, or a dissociation of the sizing and other chemical ingredients of the paper. The presence of moisture is, indeed, absolutely essential for the reaction of some substances upon one another, and it is easy to show that certain chemical compounds can be left in ultimate contact, if absolutely dry, for a lengthened period without reacting, but the addition of a little moisture at once pro- duces chemical union. This may be sho'-wn by a simple experiment. Thus a piece of coloured paper which may be bleached immediately if suspended in an atmosphere of ordinary chlorine gas will remain unbleached for several hours if first thoroughly dried in an oven and exposed to dry gas. In the case of books and papers, these conditions which promote slow disintegration are aggravated by the presence of impurities in the air, such as the vapours of burning gas, the traces of acidity in the atmosphere of large manu- facturing towns, the excessive dampness and perhaps heat of a climate favouring the growth of organisms. All these THE DETERIOEATION OF PAPER 243 factors are of varying degrees in different places, so that the deterioration of papers does not proceed in the same measure and at the same rate everywhere. Moisture. — It may not be out of place to discuss some important relations between moisture and the physical qualities of a sheet of paper. A paper in its normal con- dition always contains a certain proportion of water as one of its ingredients, and the presence of this moisture has much to do with the strength, elasticity, and use of the paper, the absence of moisture giving rise to defects and troubles in the use of the paper which to a certain extent lower its commercial value and deteriorate it, though not perhaps in the sense of permanent degradation of quality. One trouble frequently experienced by stationers and others is that known as wavy edges. The edges of a stack containing sheets of paper piled upon one another frequently twist and curl, producing what are known as wavy edges. This arises from the fact that the paper when manufactured was deficient in natural moisture, and that when stacked it has gradually absorbed moisture, which is taken up first by the edges exposed to the air. This causes unequal exj)ansion of the fibres with the production of the so-called wavy edges. The only remedy in such cases is the free exposure of the sheets before printing, so that the moisture is absorbed equally all over the sheet. The cracked edges of envelopes may be explained by reference to the same conditions. The paper is worked up into envelopes in an over-dry condition, and the fibres, being somewhat brittle, readily break apart from one another. If the paper is kept in stock for some time before use this defect can be very largely remedied. With supercalendered papers it is only possible to obtain the best results by allowing the paper to stand for several days after making before it is glazed, r2 . 244 THE MANUFACTUEE OF PAPER It is evident from these few examples that many of the troubles experienced by printers are due to the fact that orders for paper are frequently accompanied by an instruc- tion for immediate delivery, under which circumstances it is impossible to obtain the best results. The expansion of papers used for lithography, and the bad register frequently seen in colour work, may be explained by reference to the behaviour of the individual fibres towards moisture. The expansion is usually greater in one direction of the paper than in the direction at right angles to it, and this is due to the fact that fibres have a greater ratio of expansion in the diameter than in the length. The behaviour of papers when damped is a peculiarity well known to paper-makers and printers. For certain purposes it is desirable that paper should not show any material alteration when damped, since any expansion of the sheet is liable to throw the printing out of " register." The liability of papers to such stretch or expansion is largely minimised by careful manipulation of the pulp during the process of beating, and also by a proper regula- tion of the web of paper as it passes from the wet end of the paper machine over the drying cylinders to the calenders. The paper which fulfils the necessary qualifica- tions as to a minimum stretch is prepared from pulp which has not been beaten for too long a period, so that the pulp obtained is fairly light and bulky. By this means the expansion of the fibres takes place in the sheet itself with- out making any material alteration in its size. That is to say, as the sheet of paper is fairly open, there is sufficient room for expansion, w^hich thus takes place with the least alteration of the total area of the sheet. The paper which is allowed to shrink on the machine during the process of drying, without undue tension, usually exhibits a minimum amount of expansion subsequently in printing. THE DETERIORATION OF PAPER 245 It is important to notice that the expansion of paper is different for the two directions, that is for the machine and cross directions. This arises from the fact that in the machine-made paper the greater proportion of the fibres point in the direction of the machine while the paper is being made. In consequence of this the expansion of the paper is greatest in what is known as the cross direction of the paper, that is, in the direction at right angles to the flow of the pulp along the machine wire. This is to be explained by reference to the behaviour of fibres when damped or brought into contact with an excess of water. The question of the exact changes in the dimen- sions of a fibre due to absorption of water has been dealt with in an interesting manner by Hohnel. He points out that the well-known peculiarity of the shrinkage of ropes which have been lying in the water can be explained by an examination of the behaviour of the single fibres. He relates in detail the experiment which can be carried out for the exact observation of the fibres when in contact with water. A dry fibre when soaked in water appears to become 20 to 30 per cent, greater in diameter, whereas in length it is usually only increased by one-tenth per cent. The method adopted by Hohnel was to place a fibre of convenient length on a glass slip down the centre of which was a fine narrow groove capable of holding water, so that the fibre could be wetted. Over the fibre was a cover glass with a small scale marked on it. The loose end of the fibres passed over a small roller and was stretched by a light weight. The movements of the fibre were measured by means of an eye-piece micrometer. In this way it is possible to determine alterations in length to within 0*005 per cent., and this variation can be directly seen under the microscope. Hohnel observes in his account of the experiments that 246 THE MANUFACTUEE OF PAPER all fibres become thicker when wetted, that vegetable fibres are more susceptible than animal fibres. Animal fibres expand about 10 to 14 per cent, in diameter, but vegetable fibres as much as 20 per cent., as shown in the following table : — Animal Fibre. Per Cont. Vegetable Fibre. Per Cent. Human hair . Angora wool . Alpaca wool . Tussahsilk . 10-67 10-2 13-7 11-0 New Zealand flax Aloe hemp Hemp Cotton 20-0 25-8 22-7 27-5 The reverse is the case when the expansion of the fibres in regard to length is considered, since animal fibres expand 0*50 to I'OO per cent, of their length, and vegetable fibres onl}^ 0*05 to 0*10 per cent. The maximum amount of expansion in the. case of the vegetable fibres is obtained by gently breathing upon them rather than by the use of an excess of water. These figures are important as explaining many of the peculiar characteristics of vegetable and animal fibres. Advantage is taken of the greater expansion of the latter in the manufacture of instruments for thie measurement of moisture, such as the hair hygrometer, in which t)ie elongation of a stretched hair registers the variation in the moisture of the atmosphere. Quality of Book Papers. — The Committee of the Society of Arts in dealing with the evidence as to the permanence of finished papers suggest the following classification as indicating the desired standards of quality: — (A) Classification as to Fibees. A. Cotton, flax, and hemp. B. Wood celluloses, {a) sulphite process, and {h) soda and sulphate process. THE DETERIOEATION OF PAPER 247 C. Esparto and straw celluloses. D. Mechanical wood pulp. The Committee find little fault with the Principles which govern the trade in the manufacture of high-class papers, and limit the result of their investigation to the suggestion of a normal standard of quality for book papers required in documents of importance according to the following schedule : — Fibres. — Not less than 70 per cent, of fibres of Class A. Sizing. — Not more than 2 per cent, rosin, and finished with the normal acidity of pure alum. Loading. — Not more than 10 per cent, total mineral matter (ash). With regard to written documents, it must be evident that the proper materials are those of Class A, and that the paper should be pure, sized with gelatine and not with rosin. All miitations of high-class writing papers, which are in fact merely disguised printing papers, should be carefully avoided. These recommendations are good as far as they go, but in order to establish the proper standards of quality some specifications must be laid down with regard to the strength of the paper and its physical properties, together with a reference to the use for which the paper is intended. The physical condition of the paper itself apart from the nature of the fibre has much to do with its resistance to wear and tear, and this is easily proved by comparing modern book papers made from esparto with book papers of an earlier date made from the same material. The only official schedule of requirements in relation to public documents is that issued by the Stationery Office. The details set out relate chiefly to questions of weight and strength, the limits being expressed in definite form and not allowing much margin for variation in respect of strength 248 THE MANUFACTUEE OF PAPEE or fibrous constituents. Mechanical wood pulp is excluded in all papers except common material as stated in the schedule. The papers required for stock are divided into twelve classes. In each class the trade names of various sized papers are given, the size of the sheet and the weight of the ream, and, where required, any special characteristics are set out. The schedule is as follows : — Class 1. Hand-made or Mould-made. General Specification. — Hand-made or mould-made. Animal tub-sized. (''Hand-made " or '* Mould-made " to be marked on the wrapper.) Where special water-marking is required mould will be supplied by the Stationery Office for those papers made by hand. Class 2. Writings, Air-dried. General Specification. — Plate rolled. Machine made. Animal tub-sized. Air-dried. (Must bear ink after erasure.) Note. — The mean breaking strain and mean stretch required are given for each paper. The figures represent the mean of the results obtained for both directions of the sheet, and are calculated on a strip of paper five-eighths of an inch wide and having a free length of seven inches between the clips. Class 3. Writings, Ordinary. General Specification. — Rolled. Machine-made. Animal tub-sized. Class 4. Writings, Coloured. Specification. — Highly rolled. Machine-made. Animal tub-sized. THE DETERIOEATION OF PAPEE 249 Class 5. Blotting Papers. Specification.— AW rag. Machine-made. Free from loading. Class 6. Printing and Lithographic Papers. General Specification. — EoUed. Machine-made. Engine- sized. Loading not to exceed 15 per cent. Class 7. Coloured Printings. General Specification. — Kolled. Machine-made. Engine- sized. Class 8. Copying and Tissue Papers. Specification. — Machine-made. Free from loading. (Copying papers are required to give three good copies.) Class 9. Brown Papers, Air-dried. Specification. — Air-dried. Machine-made. Note. — The mean breaking strain and mean stretch required are given for each pajDer. The figures represent the mean of the results obtained for both directions of the sheet, and are calculated on a strip of paper two inches wide and having a free length of seven inches between the clips. In the case of papers indicating a larger breaking strain than the minimum required, a proportional increase in the stretch must also be shown. Class 10. Broken Paper, Cylinder -dried. General Specification.- — Machine-made. Note. — The mean breaking strain required is given for each paper. The figures represent the mean of the results obtained for both directions of the sheet, and are calculated on a strip of paper two inches wide and having a free length of seven inches between the clips. 250 THE MANUFACTUEE OF PAPER Class 11. SmaUhands. General Specification. — Machine-made. Engine-sized. Class 12. Buff Papers. Specification. — Highly finished both sides. Machine-made. Hard engine-sized. Mechanical wood pulp must not be used in the manufac- ture of any papers, with the exception of engine- sized coloured printings, and buff papers, where an addition up to 25 per cent, will be allowed. All animal tub-sized papers are required to be as far as possible free from earthy matter; and, except where specially stated, the amount of loading added to other papers must not exceed 6 per cent. When sulphite or soda pulps are used, either separately or conjointly, in the manufacture of printing papers, the quantity of neither material shall separately exceed 50 per cent. The most complete specification as to the requirements for standard papers is that published by the Paper Testing Institute in Germany, and used as the basis of most con- tracts, at least for public and official documents. Standards of Quality in Germany. — The classification of papers according to the raw materials used and the nature of the finished paper is very complete. The classification is made under three headings : {A) Kaw Material; {B) Strength; {C) Uses. {A) Classification according to Material. (1) Paper made from rags only (linen, hemp, and cotton). (2) Paper made from rags with a maximum of 25 per cent, of cellulose from wood, straw, esparto, manila, etc., but free from mechanical wood pulp. THE DETEEIOEATION OF PAPER 251 (3) Paper made from any fibrous material, but free from mechanical wood pulp. (4) Paper of any fibrous material. (B) Classification according to Strength. Class 1. 2. 3. 4. 5. 6. Mean tearing length in metres .... ;,ooo 5,000 1,000 3,000 2,000 1,000 Elasticity per cent. 4 3-5 3 2-5 2 1-5 Kesistance to folding (Schoppers' method, number of foldings) . 190 190 80 40 20 3 The tests for tearing length, resistance to folding, elas- ticity, etc., are made in air showing relative humidity of 65 per cent. The calculations for tearing length are made on strips of paper dried at 100° C. (C) Classification according to Use. Uses. Fibre. Strength. Size of Sheets. Weight of M J^ Class. Class. Cm. 1,000 1 Sq. Sheets. Kg. Metre. Grms. 1 Writing papers for im- portant documents . 1 1 33 X 42 15 — Paper for State docu- ments 1 1 26-5 X 42 12 — 2 Paper for registers, ac- count books, and ledgers— («) First quality . 1 2 33 X 42 14 — (J) Second quality 1 3 33 X 42 13 — 3 Documents intended to be preserved longer than ten years — («) Foolscap paper 2 3 33 X 42 13 — Letter paper (quarto size) 2 3 26-5 X 42 10-4 — 252 THE MANUFACTUEE OF PAPEB (C) Classification according to Use — continued. Uses. Fibre. Strength. Size of Sheets. Weight of 1 3 Class. Class. Cm. 1,000 ISq. Sheets. Metre. Kg. Grms. Documents intended to be preserved longer than ten years — C(m- tinued. Letter paper (octavo size) 2 3 26-5 X 21 5-2 Duplicating paper . 2 3 33 X 42 7 — (J)') Official writing paper . 2 4 33 X 42 13 — 4 Paper for documents of lesser importance — (a) Foolscap paper 3 — 33 X 42 12 — Letter paper (quarto size) 3 — 26-5 X 42 9-6 — Letter paper (octavo size) 3 26-5 X 21 ■ 4-8 — (Z*) Official writing paper 3 4 33 X 42 12 — 5 Envelopes and wrap- pers— (r/) First quality . — 3 — — ■ — (&) Second quality — — — — 6 Writing paper of me- dium quality . — 5—6 — — — 7 Covers for documents — (a) That required for s frequent use . 1 Tearing length 2,500 Elasticity 3-5 % 36 X 47 81-2 480 (h) For other purposes 3 Tearing length 2,500 Elasticity 2-5 % 36 X 47 42 3 250 8 Printing paper — (a) For important printed matter 1 4 — — — (J)) For less important )rinted matter 3 4 — — — (c) For common use . — 5—6 ~ — — CHAPTER XIII BIBLIOGRAPHY ANALYSIS, TECHNOLOGY, ETC. Abel, Dr. E. Hypochlorite und electrische Bleiche. Halle, 1905. Arabol Manufacturing Co. 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Laijboeck. — Tiber die Saugfahigkeit der Loschpapiere. Mitteil- ungen des k.k. Technologischen Gewerbe-Museums. Wien, 1897. Leach, C. E. — On the Shrinkage of Paper (excerpt). Newcastle, 8°, 1884. Martens, A. — Mitteilungen aus den Konigl. Technischen Yer- suchsanstalten (jahrlich). Erscheinen seit 1883. Die Jahrgange BIBLIOGEAPHY 255 1884 bis 1903 entlialten aus der Abteilung fiir Papierpriifung die im Jahrgang 1905, dieses Kalenders verzeichneten Arbeiten. Martens, A. — Apparaten ziir Uutersuchung der Festigkeitseigen- schaften von Papier. Konigl. Techn. Yersuchsanstalten. Mitteil- ungen. Erganzungsheft. No. 3. 8°, 1887. Martens, A. — Ueber Druckpapier der Gegenwart. Konigl. Techn. Yersuchsanstalten. Mittheilungen. Erganzungsheft. No. 4. 8°, 1887. Martens, A. — Untersuchung Japanischer Papiere. Konigl. Techn. Yersuchsanstalten. Mittheilungen. Erganzungsheft. No. 4. 8°, 1888. Martens und Guth. — Das konigliche Materialpriifungsamt der technischen Hochschule Berlin auf dem Gelande der Domane Dahlem beim Bahnhof Gross-Lichterfelde West. Berlin, 1904. Melnikofp, N. — Priifuiig von Papier und Pappe nebst Adressbuch der russischen Papierfabriken. Petersburg, 1906. MtJLLER, L. — Die Eabrikation d. Papiers in Sonderheit d. a. d. Maschine gefertigten. 2 Aufl. 1855. MtJLLER UND A. Haussner. — Die Herstellung u. Priifung des Papiers. 1905. MiJLLER, A. — Qualitative und quantitative Bestimmung des HolzschlifTes im Papier. 1887. Muth. Die Leimung der Papierfaser im Hollander und die Anfertigung fester Papiere. 1890. \y^ Naylor, W.— Trades Waste. London, 1902. NoRMALPAPiER. — Sammlung der Yorschriften fiir amtliche Papier- und Tintenpriifung. Berlin, 1892. PiETTE, L. — Traite de la coloration des pates a papier. Precede d'un apergu sur I'etat actuel de la fabrication du papier. Avec echantillons de papiers colores. Paris, 8°, 1863. Eejto, a. — Anleitung fur Private zur Durchfiihrung der Papier- priifung. Budapest, 1893. EossEL. — Papiere und Papierpriifung mit Beriicksichtigung der in der Schweiz verwendeten Schreib-und Druckpapiere. Biel, 1895. Schumann, Dr. G. — Welche Ursache bedingen die Papierqualitat. £ilerach, 1901. ^ SiNDALL, E. W. — Paper Technology. London, 1906. (/ Stevens, H. P.— The Paper Mill Chemist. London, 1907. Wiesner, J. — Mikroskopische Untersuchung des Papiers mit besonderer Beriicksichtigung der altesten orientalischen und europa- ischen Papiere. Wien, 1887. Wiesner, J. — Mikroskopische Untersuchung alter osturkestanischer 256 THE MANUFACTUEE OF PAPEE und anderer asiatischer Papiere nebst histologischen Beitragen zur mikroskopisclien Papieruntersuchung. Wie7i, 1902. Winkler, 0. — Die Trockengehalts-Bestimmung d. Papierstoffe. 1902. Winkler, 0., und Karstens, H. — Papieruntersuchung. 1903. WuRSTER. — Le collage et la nature du papier. Paris, 1901. WuRSTER, Dr. C. — Die neuen Eeagentien auf HolzscUiff und verholzte Pflanzenteile zur Bestimmung des Holzschliffs im Papier. Berlin. \/^ZiRM, A.— Der Papierfarber. Tilsit, 1904. CELLULOSE, ETC Beadle, 0. — Viscose and Yiscoid. Franklin Institute reprint. 1896. 1/ Bersch, J. — Cellulose, Oelluloseprodukte u. Kautschuksurrogate. 1903. BoCKMANN, F. — Das Celluloid, sein Eohmaterial, Fabrikation, Eigenschaften u. tecbnisclie Yerwendung. 1880. 2te Aufl. 1894. BoRNEMANN, G. — Ueber Cellulose and neuere Umwandlungspro- dukte derselben. Biherach, 1901. Bottler, M. — Die vegetabilischen Faserstoffe — Hartleben's cbem- iscbe technisclier Bibliothek. 1900. BuTSCHLi, O. — Untersuchgn. an Gerinnungsscbaumen, Spbaro- kystallen u. d. Sfcruktur v. Cellulose. 1894. Cross, C. F., and Bevan, E. J. — Cellulose. London, 1885. 2nd edition. 1895. '' Cross and Bevan. — Eesearcbes on Cellulose. 1895 — 1900. Ditto, 1900—1905. MtUigosches, Dr. B. — Die Yiskose, ibre Herstellung, Eigenscbaften und Anwendung. 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RouTLEDGE, T. — Bamboo considered as a Paper-making Material, with Remarks upon its Cultivation and Treatment. London, 8°, 1875. RouTLEDGE, T. — Bamboo and its Treatment. 1879. SiLBERMANN, H. — Fortschritte auf dem Gebiete der chemischen Technologic d. Gespinnstfasern, 1885—1900. 2te Tie., 1902—03. Trabut.— Etude sur I'alfa. 1889. Urbain, Y. — Les succedanes du chiffon en papeterie. Paris, 16°, 1897. Yetillart. — !&tudes sur les Fibres Yegetales. Paris, 1876. WiECK, F. G. — Bilder aus Gewerbskunst (aus Tomlinson's " Objects in Art Manufacture "), i. Papier. Lei]^)zig, sm. 8°, 1855. Witt, 0. N. — Chemische Technologic der Gespinnstfasern, ihre Geschichte, Gewinnung, Yerarbeitg. u. Yeredlung. 1888 — ^1902. Zetzsche, Die. — Wichtigsten Faserstofie der europaischen Indus- trie. Anleitung zur Erkennung und Unterscheidung. 1905. ZiMMERMANN, A. — Morphologie und Physiologic der Pflanzenzelle. HISTORICAL. ' Blanchet, Augijstin. — Essai sur I'histoire du papier et de sa fabrication. Paris, 1900. Breitkofe, J. G. J. — Ursprung der Spielkarten, die Einfiihrung des Leinenpapieres, etc., in Europa. (Completed by J. G. F. Roch.) Leipzig, 2 vols., 4°, 1784—1801. Briquet, C. M. — Bermerkungen iiber das Sammeln von Wasser- zeichen oder Papiermarken, uberreicht bei der Ausstellung der alten Papiermarkerkunst zu Paris. 1900. Briquet, C. M. — Papiers et filigranes des archives de Genes 1154—1700. Geneva, 1888. Briquet, C. M. — Geschichte der Papierzeichen von ihrem Erscheinen gegen 1282 bis 1600. Mit Beigabo von 15500. 1906. BIBLIOGRAPHY 259 Butler Paper Co. — The Story of Paiier-making. Chicago, sm. 8°, 1901. CoLLETT, 0. D. — History of Taxes on Knowledo^e. London, 1899. Congress. — International congress de fabricants de papier et carton, Antwerp. Comptes rendu des seances. Bruxelles, 8°, 1894. Dropisch, B. — Die Papiermaschine, ihre gescliiclitliclie Entwick- lungu. Construction. 1878. Egger, E. — Le papier dans I'antiquite et dans les temps modernes. Paris, 16°, 1866. 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Farts, 1. 8'^, 1864. Beadle, C. — Paper Manufacture — Lectures. 1901. Beadle, 0. — Chapters on Paper-making. Vol. 1. London, 1904. Vol. 2, Answers to Teclinological Questions. 1906. Vol. 3, Practical Points in Paper Manufacture. 1907. Vol. 4, Ditto. 1907. Beaumont, F. — Eeport on Apparatus and Processes used in Paper- making, etc. Paris Universal Exhibition, 1867. British Commercial Eeports, Vol. 4. 8°, 1867. Bennett, J. B. — Paper-making Processes and Machinery, with Illustrations of Paper-making Machinery constructed by Bertrams, Ltd. , Edinburgh, 8°, 1892. Bertrams, Ltd. — Specimens of Paper. Edinhurgh, obi. 16°, 1892. Blanchet, .1. — Fabrication du papier. Eapports, Paris Universal Exhibition, 1900. Brown, H. T. — The Manufacture of Paper from Wood in the United States. 1886. BuROT. — Note sur la fabrication du papier de paille. Paris, 8°, 1883. Campredon, E. — Le Papier. I^tude monographique sur la papeterie Fran9aise et en particulier sur la papeterie Charentaise. i. 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Leith, 12°, 1881. Hartmann, C. — Handb. d. Papierfabrikation. Taf. 1842. Hassak, K. — Die Erzeugung des Papieres. Hatjsnee, a. — Der Hollander. Eine kritische Betracbtung seiner Arbeitsweise mit Bezug auf die Einzelabmessungen seiner Telle und die verarbeiteten Easern. 1901. Heering, E. — Paper and Paper-making, Ancient and Modern. London, 8°, 1854. Ditto, 2nd edition, 1855. Ditto, 3rd edition, 1863. HoFMANN, C. — A Practical Treatise on the Manufacture of Paper in All its Branches. Philadelphia, 4°, 1873. HoFMANN, 0. — Praktisches Handbuch d. Papierfabrikation. 1873. Hoffmann, Th. — Papierpragung. Berlin. HoYER, E. — Das Papier, seine BeschaflPenheit und deren Priifung. Munchen, 1882. HoYER, E. — Uber die Entstehung und Bedeutung der Papiernor- malien, sowie deren Eiufluss auf die Eabrikation des Papieres. Munchen, 1888. HoYER, E.— Die Eabrikation des Papiers. 1900. HoYER, E. — Die Eabrikation des Papiers, nebst Gewinnung d. Easern. 1887. HuBNER, J. — Paper Manufacture (Cantor Lectures to the Society of Arts). 1903. Jagenberg, E. — Das Hollandergeschirr. Eemscheid. 1894. Kirchner-Strohbach. — Hollander- Theorie. Biberach. 1904. Klemm, Dr. p. — Tiber Papier. Klimsch's Graphische Bibliothek Bd. 3 (Earbe und Papier im Druckgewerbe). 2 Teil. Frankfurt . if. 1900. KoRSCHiLGEN TJND Selleger. — Tcchnik und Praxis d^ Papier- fabrikation. Berlin, 1906. Kraft, M. — Grundriss der mechanischen Technologic. Abt. ii. Spinnerei, Weberei, und Papier-fabrikation. 2te Aufl. Wieshaden, 8°, 1895. Lenormand, L. S. — Manuel du fabricant de papier. Paris, 2 vols., 18°, 1833. Ditto, 2nd edition. 1834. J 264 THE MANUFACTUEE OF PAPEE Lenormand, L. S. — Nouveau manuel complet du , . . fabricant de papiers peints. Nouv. ed. par Yergnand. Paris, 18°, 1854. Lenojrmand, L. S. — Handbuch der gesammten Papier-fabrikation, 2te Aufl, von 0. Hartmann. Weimar, 2 vols., 12°, 1862. Meez. — Bebandlung der Papiermaschine. Meynier, H. — Papier und Papier- Eabrikate. Paris Univ. Exhibi- tion, 1867. Austrian Comm. Berichte. Heft 8. 8°, 1867. Mierzinski, St. — Handbuch d. Papierfabrikation. 3 Bde. 1886. Mullee,, E. a. L. — Die Eabrikation des Papiers, in Sonderheit der auf der Mascbinen gefertigten, etc. 3fce Aufl. Berlin, 8°, 1862. Mullee, De.. L. — Die Eabrikation des Papiers. Berlin, 1877. Olmee, Geoeges. — Du papier mecanique. Onfeoy. — L'art du papier et le papier d' Arches. 1907. Papee-Making. — Paper-making, by the Editor of the Paper Mills Directory, London. 2nd edition. 8°, 1876. Papee-Makee. — The Paper-makers' Handbook and Guide to Paper- making, by a Practical Paper-maker. London, sm. 8°, 1878. Paper-Manufactuee. — Essays by a Society of Gentlemen. No. vi., pp. 21—27. 1717. Paekinson, E. — Treatise on Paper, with Outline of Manufacture. 1886. Ditto, 2nd edition, 1896. Payen, a., and othees. — La fabrication du papier et du carton. 3e ed. Paris, 8°, 1881. 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Hamburg, 1888. Reed, A. E. — Paj)er Manufacture. Society for ttie Promotion of Scientific Industry. Artisans' Reports upon the Vienna Exhibition. 8°, 1873. Richardson, W. H. — The Industrial Resources of the Tyne . . . [Paper]. 1864. Schubert, M. — Traite pratique de la fabrication de la cellulose. Trad. p. E. Bibas. Toile. 1893. Schubert, M. — Die Praxis der Papierfabrikation mit besond. Berucksichtigung der Stoffmischungen und deren Calculationen. 1897. Schubert, M. — Die Papier verarbeitung. 2 Bde. 1900 — 1901. Bd. 1. Die Kartonnagen Industrie. Bd. 11. Die Buntpapierfabrikation. / SiNDALL, R. W.- The Manufacture of Paper Pulp in Burma. Government Press. Rangoon, 1907. SiNDALL, R. W.— The Manufacture of Paper. 1908. Constable & Co. London. Twerdy, E. — Papier iudustrie. Berichte. Wien, 1873. Vachon, M. — Les arts et les industries du jDapier. France, 1871 —1894. Yalenta, E. — Das Papier, seine Herstellung, Eigenschaften, Prii- fung. 1904. Wanderley, G.— Die Papierfabrikation und Papierfabrikanlage. Leipzig, 1876. Watt, A. — The Art of Paper-making, with the Recovery of Soda from Waste Liquors. London, sm. 8°, 1890. Weber, R. — Paper Industrie. Yienna Universal Exhibition, 1873. ' Wehrs, G. E. — Yom Papier, den vor den Erfindung desselben iiblich gewesenen Schreibmassen und sonstigen Schreibmaterialien. Halle, 8°, 1789. Winkler, 0. — Der Papierkenner. 1887. PAPER, SPECIAL KINDS. Andes, L. E. — Papier- Spezialitaten, praktische Anleitung zur Herstellung. 1896. 266 THE MANUFACTURE OF PAPER \/ Andes, L. E. — Treatment of Paper for Special Purposes. Trans- lated from German. 1907. Andes, L. E. — Die Fabrikation der Papiermache und Papierstoff- Waren. Leijpzig, 1900. Andes, L. E. — Blattmetalle, Bronzen und Metallpapiere, deren Herstellnng und Anwendung. Wien, sm. 8°, 1902. Boeck, J. P. — Die Marmorirkunst far Buchbindereen, Buntpapier- fabriken. Wien, sm. 8°, 1880. Briquet, M. — De quelques industries nouvelles dont le papier est la base. Qeneve, 1885. ExNER, W. F. — Tapeten-und Bunt-papier Industrie. Paris Univ. Exhibition, 1867. Austrian Comm. Bericbte. Heft 8. 1867. ExNER, W. F. — Tapeten-und Bunt-papier. Vienna Universal Exhibition, 1873. Officieller Ausstellungs-Bericbt. Heft 53. 8°, 1873. FiCHTENBERG. — Nouveau manuel complet du f abricant de papiers de fantaisie, papiers marbres, etc. Paris, 18°, 1852. Herring, R. — Guide to Yarieties and Value of Paper. 1860. HoFMANN, A. W. — Report on Vegetable Parchment (Gaine's Patent, No. 2834 of 1853). London, 8^, 1858. Kaeppelin, D. — Fabrication des papiers peints. Lacroix E., Etudes sur I'exposition de 1867. Vol. 1. 8°, 1867. Kaeppelin, D. — Fabrication des papiers peints. 1881. LiNDSEY, G. — Pens and Papiermache. Bevan, G. P., Brit. Manu- facturing Industries (iii.). 12°, 1876. Morton, G. H. — The History of Paper-hangings, with Review of other Modes of Mural Decoration. Liverpool, 8°, 1875. [^ Sanborn, K.— Old Time Wall Papers. 1905. Schmidt, C. H. — Die Benutzung des Papiermache. Weimar, 12°, 1847. Schmidt, C. H. — Die Papier-Tapetenfabrikation. 3te Aufl. Weimar, 12°, 1856. Schmidt, C. H. — The Book of Papiermache and Japanning. London, 1850. Seeman, Th. — Die Tapete, ihre aesthetische Bedeutung u. Techn. Darstellung, sowie kurze Beschreibung der Buntpapierfabrik. 1882. SiLCOX. — Manufacture of Paper Barrels. Vienna Exhibition, 1873. U.S.A. Reports, ii. Smee, a. — Report on Vegetable Parchment (Gaine's Patent, No. 2834 of 1853). London, 8°, 1858. BIBLIOGEAPHY 267 Thon, C. F. G. — Der Fabrikant bunter Papier, 3te Aufl. Weimar^ 12°, 1844. ^ Weichelt, a. — Buntpapier Fabrikation. Berlin, 8°, 1903. Whiting Paper Co.^ — How Paper is Made. Holyohe, Mass., 32°, 1893. WiNZER, A.— Die Bereitung und Benutzung der Papiermache und ahnlicher Komj)Ositionen, 3te Auli. Weimar, 12°, 1884. (y Ditto, 4tli edition, 1907. WooLNOTJGn, C. W. — The Whole Art of Marbling, as applied to Paper, Book Edges, etc. London, 8°, 1881. Wyatt, Sir M. D. — Eeport on Paper-hangings. Paris Univ. Exhibition, 1867. Brit. Comm. Eeport, Vol. II. 8°, 1867. STATISTICS AND VARIOUS. Akessok — Lexikon der Papier-Industrie. Dentsch-Englisch- Franzosisch, 2te Aufl. 1905. Archer, T. C. — British Manufacturing Industries. Vol. 15. Industrial Statistics. London. Barth, E. — Arbeitsregeln fur Fabriken mit besonderer Berucksich- tigung von Papier-fabriken. Karlsruhe, 1897. Baudisch, J. — Einige ins Papierfach schlagende Berechnungen. Biberach. 1893. Dyson. — Mosely Commission Eeport. Manchester, 1903. Ermel. — Eapport sur le materiel et les procedes de la papeterie, etc. Paris Univ. Exhibition, 1878. Eapports. Class 60. 8^, 1881. Foreign Ofeice, No. 4 (1871). — Eeports on the Manufacture of Paper in Japan. London, fol., 1871. Geyer, a. — Eegistry of Water-marks and Trade-marks. ' Compiled from the American Paper Trade (2nd edition). Neiu York, 1898. Ditto, 5th edition, 1903. Gratiot, A. — Description de la papeterie d'Essonnes, London International Exhibition of 1851, Prospectuses of Exhibitors. Vol. 2. 8°, 1851. Krawany, F. — Warte der Papier-Halbstoff-und Pappenfabriken Oesterreich-Ungarns. 1905. Landgraf, J. — Papier-Holzschliff und seine Zollpolitische Wurdi- gung. Mannheim. LocKWOOD & Co. — American Dictionary of Printing and Book- binding. New York, 1895. 268 THE MANUFACTUEE OF PAPEE Ltjdwig, G. — Trockengelialts-Tabellen. Pima, 1897. MacNaughton, J. — Factory Book-keeping for Paper Mills. 1900. Mahrlen. — Papierfabrikation, im Konigr. Wiirttemburg (im Jabre 1860). Stuttgart, 8°, 1861. l/ (y Marr, D. — Kosten der Betriebskrafte bei 1 — 24 stiindiger Arbeitszeit taglich und unter Beriicksicbtigung des Aufwandes f iir die Heizung. Munchen u. Berlin. Melnikoff, N. — Lebrbucb der Papier-Holzscbliff, Zellstoff und Pappenfabrikation. Fetersburg, 1905. Melnikoff, N. — Kleines bandbucb Papierfabrikation. Fetersburg, 1906. Melnikoff, N. — Gescbicbte, Statistik n. Literatur der paper- industrie nebst russiscben Wasserzeicben. Fetersburg, 1906. Mijnsell, J. — Cbronology of Paper-making. Albany, 8°, 1857. Ditto, 4tb edition, 1870. MxJNSELL, J. — Cbronology of tbe Origin and Progress of Paper and Paper-making. Albany, 1876. MuNSELL, J. — Observations Illustrative of tbe Operation of tbe Duties on Paper. London, 8°, 1836. MuNSELL, J. — Materiel et procedes de la papeterie, etc., 1889. Eapports du Jury. Class 58. 8°, 1889. Paris Uniy. Exhibition.— Papiers points, 1889. Eapports du Jury. Classe 21. 8°, 1891. 1 / Passerat, a. L. — Bareme complet pour papeteries. Faris. Patents. — Patent Abridgments. Class 96. Patent Office Abstracts on Paper-making. From 1855 to date. > EoULHAC. — Papeterie. Paris Univ. Exbibition, 1867. Eapports du Jury. Classe 7, sect. 1. 8°, 1868. Sampson, J, T. — Paper-staining. Mansion House Committee. Artisans' Eeports, Parisb Exbibition. 8°, 1889. Treasury. — Eeport of tbe Excise Commission. 1835. YoGEL, K. — Papier-industrie, etc., Auf der Weltausstellung in Chicago. Chicago Exhibition, 1893. Austrian Central Committee. Officieller Bericht. Heft iv. 8°, 1894. YoiGT, G. — Papiergewichtstabellen. Merseburg, 3 894. I / Ward, Sir W. — Eeport on German Paper-making Industry. V Parliamentary Paper, 1905. Water-marks. — Water-marks and Trade-marks Eegistry (2nd ed.). New York, 16°, 1898. BTBLIOGEAPHY 269 WOOD PULP AND PULP WOOD. British and CoLomAL Printer. — History of Wood Pulp. Vol. 8. 1882. Dunbar. — Wood Pulp and Wood Pulp Papers. EiTTiCA, Dr. F. — Geschiclite der Sulfitzellstoff-fabrikation. Leipzig, 1901. FiTTiCA, Dr. F. — Forestry and Forest Products. [Edinburgh. Forestry Exhibition. 1884.] GoTTSTEiN. — Holzzellstoff in seiner Anwendung fur die Papier und Textil-Industrie und die bei seiner Herstellung entstebenden Abwasser. 1904. Griffin, M. L. — Sulphite Processes. American Society 0. E. 417. 18S9. Harper, W. — Utilisation of Wood Waste by Distillation. U.S.A., 1907. Harpf, a. — Die Erzeugung von Holzschliff und Zellstoff. Wien, 1901. Harpf, A. — ^Fliissiges Schwefeldioxyd. Stuttgart, 1901. Hubbard. — Utilisation of Wood Waste. 1902. \J Johnson, G.— Wood Pulp of Canada. 1902—08. Yearly. MiCHAELis, 0. E. — Lime Sulphite Fibre Manufacture in the United States. With Eemarks on the Chemistry of the Processes, by M. L. Griffin (excerpt). Neiu York, 8°, 1889. Phillips, S. C— Uses of Wood Pulp. 1904. EosENHEiM, G. M. — Die Holzcellulose. Berlin, 1878. Schubert, M. — Die Holzstoff oder Holzschliff-fabrikation. 1898. Schubert, M. — ^Die Cellulosefabrikation (Zellstoff-fabrikation). Praktisches Handbuch fur Papier-u. Cellulose-techniker. 1906. SiNDALL, E. W.— The Sampling of Wood Pulp. London, 8°, 1901. Veitch, L. p.— Chemical Methods for Utilising Wood. U.S.A. Department of Agriculture. 1907. Veitch, L. P.— Wood Pulp, Uses of. U.S.A. Consular Eeports, vol. xix. Banks and Crate. — Pulpwood Problems. Letters to the Glohe, Toronto, Canada. 1907. Gamble, J. — Indian Timbers. Graves. — The Woodsman's Handbook. U.S.A. PiNCHOTT, G.— Forestry Primer. U.S.A., 1900. 270 THE MANUFACTUEE OE PAPEE PiNCHOTT, Gr. — The Adirondack Spruce. U.S.A. Eattray, J., AND Mill, H. E.— Eorestry and Forestry Products. Ed'inlurgh, 1885. SCHLICH. — Forestry Manual. Some more or less interesting articles on '' Paper " will be found in the following encyclopaedias, etc. : — DATE. 1738. Chambers's Encyclopsedia. 1757. Barrow. Dictionary of Arts. 1759. New. Universal History of Arts. 1770. Eoyal Dictionary of Arts. 1788. Howard. A Eoyal Encyclopsedia. 1806. Gregory. A Dictionary of Arts and Sciences. 1 807. Encyclopaedia Perthensis. 1809. Nicholson. The British Encyclopaedia. 1813. Martin. Circle of the Mechanical Arts. 1813. Pantologia. 1819. Eees' Cyclopaedia. 1821. Encyclopaedia Londoniensis. 1827. Jamieson's Dictionary. 1828. Oxford Encyclopaedia. 1829. The London Encyclopaedia. 1830. Edinburgh Encyclopaedia. 1833. Phillip's Dictionary of Arts. 1835. Partington. British Cyclopaedia. 1836. Archaeologia, vol. xxvi. , 1836. Barlow. Encyclopaedia of Arts. 1840. The Penny Encyclopaedia. 1845. Encyclopaedia Metropolitana. 1848. Useful Arts of Great Britain. S.P.C.K. 1851. Knight's Cyclopaedia of Industry. 1855. Appleton's Dictionary of Mechanics. 1860. Hebert. Mechanic's Encyclopaedia. 1861. Knight's English Cyclopaedia. 1861. New American Cyclopaedia. 1866. Tomlinson's Dictionary of Arts. 1871. Yeats. The Technical History of Commerce. 1874. Clarke's Practical Magazine. 1875. Ure's Dictionary of Arts. BIBLIOGEAPHY 271 1875. Globe Cyclopsedia. 1876. American Meclianical Dictionary. 1877. Johnson's Universal Cyclopaedia. 1880. Wylde. Industries of the World. 1882. Simon's Encyclopaedia of Manufactures. 1886. Encyclopasdia Britannica. 1889. Chambers's Encyclopaedia. 1889. Blaikie. Modern Cyclopaedia. 1890. Popular Encyclopaedia. 1892. Spon's Workshop Eeceipts. 1903. Gilman. International Encyclopaedia. 1904. Encyclopaedia Americana. 1904. Tweney's Technological Dictionary. 1 Newspapers. England. Papermaker and British Paper Trade Journal. S. C. Phillips, London. Papermakers' Circular. Dean & Son, London. Papermakers' Monthly Journal. Marchant, Singer & Co., London. Paper Box and Bag Maker. S. C. Phillips, London. Papermaking. London, The Paper and Printing Trades' Journal. London, World's Paper Trade Eeview. W. J. Stonhill, London. V Canada. Pulp and Paper Magazine. Biggar- Wilson, Ltd., Toronto. United States of America. American Bookmaker. Howard Lockwood & Co., New York. The Paper Trade. Chicago. The Stationer. Howard Lockwood & Co., New York. Paper Mill and Wood Pulp News. L. D. Post & Co., New York. Paper Trade Journal. Howard Lockwood & Co., New York. The Paper World. C. W. Bryan & Co., Holyoke, Mass. K/ France. Bulletin Journal des Fabricants de Papier. Paris. Journal des Papetiers. M. Edmond Eousset, Paris. Le Moniteur de la Papeterie Fran^-aise. Paris. 272 THE MANUFACTUEE OF PAPEE La Papeterie. Paris. La Eevue de la Papeterie Fraiigaise et Etrangere. M. Edmond Eousset, Paris. Le Papier. H. Everling, Paris. Germany. \J Centralblatt fur die Osterreicliiscli Ungarisclie Papierindustrie. Adolf Hladufka, Wien. Der Papierfabrikant. Otto Eisner, Berlin. Der Papier Markt. Carl Dobler, Frankfurt a. Main. Deutsche Papier und Scbreibwarenzeitung. S. Eichter, Berlin. Die Postkarte. Gustav Fahrig, Leipzig. Export-Journal. G. Hedeler, Leipzig. Holzstoff-Zeitung, Camillo Dracbe, Dresden. Papierhandler Zeitung fur Osterreichungarn. Wien. Papier-Industrie. Berlin. Papier-und Scbreibwaren -Zeitung. Wien. Papier-Zeitung. C. Hofmann, Berlin. Scbweizer Grapbischer Central- Anzeiger. H. Keller, Luzern. Wocbenblatt fiir Papierfabrikation. Guntter-Staib Biberach (Wurtt). Wocbenschrift fur den Papier-und Sckreibwarenhandel. Dr. H. Hirschberg, Berlin. BIBLIOGRAPHY 272a ANALYSIS, TECHNOLOGY. Beadle and Stevens.— Blotting paper, nature of absorbency. 1905. Winkler. — Estimation of Moisture in V/ood-pulp. 1902. Trans- lated by Dr. H. P. Stevens. Hauptversammlung. — Published annually by the Verein der Zellstoff und Papier- Cbemiker. Berlin, 1907 et. FIBRES, etc. -'' Dodge, C. R. — Catalogue of useful Fibre-plants of the World. Report No. 9. Dept. of Agriculture. Z7.>S..l., 1897. Duchesne, E. A. — Repertoire des plantes utiles et des plantes veneneuses du globe, etc. Braxelles, 1846. Gabalde, B. — Essai sur le bananier et ses applications a la fabrica- tion de papier. 1843. MoNTESSUS DE Ballore. — Alfa et papier d'Alfa. 1908. Pecheux. — Les textiles, les tissus, le papier. 6 pp. Paris, 1907. Renoxjard. — Etudes sur les fibres textiles. Paris. Renouard. — Les fibres textiles de I'Algerie. Paris. Riviere, x\.uguste et Charles. — • " Les Bambous." Socicte d'Acclimatation. Paris. Richmond, G. F.— Philippine Fibres and Fibrous Substances. Manila, Bureau of Printing, 1906. HISTORICAL. Briquet, C. M. — Recherches sur les premiers Papiers employes du X*^ au XIV« siecle. pp. 77. Paris, 1886. ■ Briquet, C. M. — De la valeur des Filigranes du Papier comme moyen de determiner I'age de documents, pp. 13, Geneve, 1892. Briquet, C. M. — La Legende paleographique du Pa|)ier de Coton. pp. 18. Geneve, 1884. Briquet, C. M. — Lettre sur les Papiers usites en Sicile a I'occasion de deux manuscrits en papier dit le coton. 16 pp. Palermo, 1892. Desmarest, N. — Art de la Papeterie. Paris, 1879. Delon, C. — Histoire d'un livre. Paris, 1879. 272b the MANUFACTUEE OF PAPER DiDOT, A. F. — Le centenaire de la Machine a Papier continu. pp. 79. Paris, 1900. DiCKiisrsoN, J.— Dickinson's Paper Mills. Calcutta, 1884. GiRARD, A. — Le Papier ses ancetres ; son histoire. Lille, 1892. JuLiEN, S. — Description des procedes chinois pour la fabrication du papier. Traduit de I'ouvrage cliinois par Thien-Kong-Kha-We. 1840. Eay, J. — Paper, its history, pp. 100. London, 1893. Lempertz, H. — Beitrage zur Geschichte des Leinens Papiers. I<:oln, 1891. PAPER MANUFACTURE. BoRY, P. — Les Metamorphoses d'un Chiffon. Ahheville, 1897. Chabrol, L. — La Eeglenientation du Travail dans I'mdustrie du papier, pp. 168. Paris, 1901. Demuth, F. — Die Papier Fabrikation. 1903. Demuth, F. — Die Storungen in deutschen Wirtschaftsleben 1900. Leipzig, 1903. LiMOGE. — Cercles d' Etudes commerciales, Le Papier, pp. 140. Limoge, 1892. PAPER, SPECIAL KINDS. Spalding and Hodge. — Printing papers ; a handbook. London, 1 905. STATISTICS, etc. Beadle, C. — Development of Water-marking. London, 1906 (Society of Arts). DiJMERCY. — Bibliographie de la Papeterie. pp. 28. Bruxelles, 1888. Bruce, H. — Gladstone and Paper Duties. Edinburgh, 1885. Ellis, J. B. — Hints for the Paper Warehouse. Leeds, 1887. Webster, J. — Synopsis of Sizes of Paper. Southport, 1889. Whitson, W. — The Concise Paper Calculator. Edinburgh, 1903. WOOD PULP, etc. Dropisch, B. — Holzstoff et Holzcellulose. Weimar, 1879. INDEX Acid dyes, 201 in papers, 239 size, 170 Agave, 40 Alum, 167, 168 Aniline dyes, 201 sulphate, 121 Animal size, 63, 164 Antichlors, 163 Art paper, 142 imitation, 145 testing, 147 Asbestos, 174 Ash in paper, 171 Backwater, 120, 205 Bagasse, 41 Bamboo, 43 Barker, 97 Beating engines, 186 patents, 192 power consumed, 191 Beating, conditions of, 197 early methods of, 176 experiments in, 179 process of, 58, 175 Bibliography, 253 Bisulphite of lime, 159 Bleaching, 57, 83 powder, 161 Blue prints, 140 Board machine, 132, 135 Boards, manufacture of, 131 duplex, 132, 134 Book papers, quality of, 246 Books, decay of, 237 Brown papers, 127 Carbonic acid recorder, 215 Casein, 165, 235 Caustic soda, 81, 155 Cellulose, 21 derivatives of, 29 hydrolysis of, 27, 229 oxidation of, 28 percentage of, in plants, 23 properties of, 26 Chemical residues in paper, 238 wood pulp, 104 Chemicals, 153 China clay, 117, 150, 171, 204, 234 Coal consumption, 214 Coated paper, 142 Cold ground pulp, 100 Colophony, 169 Colour of paper, fading of, 203, 241 matching, 205 unevenness of, • 203 Colouring of paj)er pulp, 199 analysis of, 206 Cotton, 22, 69 274 INDEX Cyanotype papers, 140 Cylinder machine, 131 Density of paper, 181 Deterioration of paper, 228, 246 Digesters, 52, 89, 109 Dilution tables, 157, 163 Duplex boards, 134 Dyeing of paper, 199 EiBEL patent, 223 Electrical power, 219 Electrolytic bleaching. 57 Engine sizing, 117, 167 Esparto, 72 bleaching of, 83 composition of, 73 test for, in papers, 87 yield of, 77 Evaporation apparatus, 76, 79 tables, 81 Eeatherwbight papers, 232 Fibres for paper-making, 38 examination of, 43 I'eagents for staining, 71 Elax, 40 Eourdrinier machine, early, 16 Erench chalk, 173 GrAS producer, 218 Gelatine, 63, 164, 237 Glue, 137, 142, 235 Grinders, 100 History of paper, 1 Hoernle, 7 Hollander, 16, 59, 176, 185 Hot ground pulp, 100 Imitation art paper, 145, 235 Kraft paper, 129 parchment, 137 Improvements in paper-making, 214 Iron in paper, 229 Kraft papers, 128 Laid papers, 66 Lime, 52, 157 bisulphite, 159 sulphate, 173 Linen fibre, 70 Loading, 171 M. G. caps, 130 Machinery, 214, 224 Manila paper, 127 Mechanical pulp, 95 detection of, 121 Metanil yellow, 122 Middles, 134 Mitscherlich pulp, 107 Moisture, influence of, 243 Multiple effect evaporation, 79 Neutral size, 169 Newspaper, 116, 215 Output of a paper machine, 122 Paper, art, 142 ash in, 171 brown, 127 bulk of, 231 chemical residues in, 238 clay in, 234 colour of, 199, 241 colour in, analj^sis of, 207 deterioration of, 229 fibres for, 38 history of, 1,5 iron in, 239 permanence of, 230 INDEX 275 Paper, rags used for, 47 sizing of, G3 special kinds of, 137 standards of quality, 246 strength of, 184, 231 surface of, 233 volume composition of, 233 Paper machine, early, 16 outj^ut of, 122 Papier-mache, 150 Papyrus, 2, 42 Paraffin paper, 148 Parchment, 4 paper, 137 Peat, 41 Phloroglucine, 121 Pigments, 199 Porion evaporator, 76 Presse-pate, 86 Prussian blue, 200 Eaq paper, manufacture of, 47 origin of, 5 Eags, bleaching, 55 boiling, 51 classification, 48 sorting, 48 Ramie, 40 Records, early, 1 Recovered ash, 158 Recovery processes, 78, 113 Refiners, 90 Rope browns, 127 .Rosin size, 117, 169, 236 Screens, 102 Sealings, 129 Shrinkage of paper, 181 Sizing of paper, 63, 117, 167 Society of Arts, 246 Soda, 153 Soda pulp, 107, 113 recovery, 78 silicate of, 166, 171 Softening of water, 216 Spent liquors, 78, 113 Staining reagents for fibres, 71 Standards of quality, 246, 248, 250 Starch, 166, 237 Stationery Office, 248 Stone beater rolls, 189 Straw, 88 Sulphate pulp, 107 Sulphite pnlp, 107 Sulphites, 159, 163 Supercalender, 65 Superheated steam, 218 TiNEOiL paper, 148 Transfer paper, 149 Ultramarine, 199 Volume composition of paper, 233 Vulcanised fibre, 139 Water softening, 216 Watermarks, 67 Wavy edges, 243 Waxed paper, 147 Wet press machine, 103 Wiesner, 6 Wiilesden paper, 139 Wood, 22 pulp, 95 chemical, 104 mechanical, 95 soda, 107, 113 sulphite, 107 Wove papers, 66 Wrappers, 127 BKADBURY, AGNEW, & CO. LD., PBINTKRS, LONDON AND TONBRIDGE. VAN NOSTRAND'S "Westminster Series Bound in uniform style. Fully Illustrated. Price $200 net each. The Volumes in the '' Westminster''' Series have been designed to meet the growing demand for books on practical subjects ; to bring within the ken of the non-technical reader an accurate knowledge of manufacturing processes and the practical appli- cation of modern science to industries. Each volume is written by an expert to the end that practical readers and all who are engaged in the numerous allied branches of the engineering and technical trades may have reliable works of reference. The series provides for a class not hitherto reached in published works. The volumes can be easily read by the general public, and make excellent handbooks at a moderate price for the student. The series is well suited to public libraries and will be found valuable for libraries in engineering shops and factories. D. VAN NOSTRAND COMPANY T^uhlishers and booksellers 23, Murray and 27, Warren Streets, New YorK. THE "WESTMINSTER" SERIES CoaL By James Tonge, M.I.M.E., F.G.S., etc. (Lecturer on Mining at Victoria University, Manchester). With 46 Illustrations, many of them showing the Fossils found in the Coal Measures. List of Contents : History. Occurrence. Mode of Formation of Coal Seams. Fossils of the Coal Measures. Botany of the Coal-Measure Plants. Coalfields of the British Isles. Foreign Coalfields. The Classification of Coals. The Valuation of Coal. Foreign Coals and their Values. Uses of Coal. The Production of Heat from Coal. Waste of Coal. The Preparation of Coal for the Market. Coaling Stations of the World. Index. This book on a momentous subject is provided for the general reader who wishes accurate knowledge of Coal, its origin, position and extent, and its economical utilization and application. Iron and SteeL By J. H. Stansbie, B.Sc. (Lond.), F.I.C. With 86 Illustrations. List of Contents : Introductory. Iron Ores. Combustible and other materials used in Iron and Steel Manufacture. Primitive Methods of Iron and Steel Production. Pig Iron and its Manu- facture. The Refining of Pig Iron in Small Charges. Crucible and Weld Steel. The Bessemer Process. The Open Hearth Process. Mechanical Treatment of Iron and Steel. Physical and Mechanical Properties of Iron and Steel. Iron and Steel under the Microscope. Heat Treatment of Iron and Steel. Elec- tric Smelting. Special Steels. Index. The aim of this book is to give a comprehensive view of the modern aspects of iron and steel, together with a sufficient account of its his- tory to enable the reader to follow its march of progress. The methods of producing varieties of the metal suitable to the requirements of the engineer, foundryman and mechanician are described so that the worker may learn the history of the material he is handling. Natural Sources of Power. By Robert S. Ball, B.Sc, A.M. Inst. C.E. With 104 Diagrams and Illustrations. Contents : Preface. Units with Metric Equivalents and Abbre- viations. Length and Distance. Surface and Area. Volumes. Weights or Measures. Pressures. Linear Velocities, Angular Velocities. Acceleration. Energy. Power. Introductory Water Power and Methods of Measuring. Application of Water Power to the Propulsion of Machinery. The Hydraulic Turbine. Various Types of Turbine. Construction of Water Power Plants. Water Power Installations. The Regulation of Turbines. Wind Pressure, Velocity, and Methods of Measuring. The Application of Wind Power to Industry. The Modern Windmill. Con- structional Details. Power of Modern Windmills. Appendices A, B, C. Index. Two departments of Engineering and their applications to industry form the subject of this volume; the "natural" sources of water ( 2 ) THE "WESTMINSTER" SERIES and wind power which supply mechanical energy without any inter- mediate stage of transformation. Most people will be surprised at the extent to which these natural power producers arc used. The widespread application of water power is gcnerall}^ known, but it is interesting to learn that the demand for windmills was never so great as it is to-day, and there are signs of abnormal expansion in the direc- tion of their useful application in the great agricultural countries of the world. Though primarily of importance to the engineer, this work will be of great interest to every manufacturer who in economizing his means of power production can take the natural forces that lie to his hand and harness them in his service. The author is the son of Sir Robert Ball, the eminent mathematician and astronomer. Liquid and Gaseous Fuels, and the Part they play- in Modern Power Production. . By Professor Vivian B. Lewes, F.I.C, F.C.S., Prof, of Chemistry, Royal Naval College, Greenwich. With 54 Illustrations. List of Contents : Lavoisier's Discovery of the Nature of Com- bustion, etc. The Cycle of Animal and Vegetable Life. Method of determining Calorific Value. The Discovery of Petroleum in America. Oil Lamps, etc. The History of Coal Gas. Calorific Value of Coal Gas and its Constituents. The History of Water Gas. Incomplete Combustion. Comparison of the Thermal Values of our Fuels, etc. Appendix. Bibliography. Index. The subject of this book has, during the last decade, assumed such importance that it is hoped this account of the history and develop- ment of the use of various forms of combustible liquids and gases for the generation of energy may do some service in its advancement. Electric Power and Traction* By F. H. Davies, A.M.I.E.E. With 66 Illustrations. List of Contents : Introduction. The Generation and Distri- bution of Power. The Electric Motor. The Application of Electric Power. Electric Power in Collieries. Electric Power in Engineering Workshops. Electric Power in Textile Factories. Electric Power in the Printing Trade. Electric Power at Sea. Electric Power on Canals. Electric Traction. The Overhead System and Track Work. The Conduit System. The Surface Contact System. Car Building and Equipment. Electric Rail- ways. Glossary. Index. The majority of the allied trades that cluster round the business of electrical engineering are connected in some way or other with its power and traction branches. To members of such trades and callings, to whom some knowledge of applied electrical engineering is desirable if not strictly essential, the book is particularly intended to appeal. It deals almost entirely with practical matters, and enters to some extent into those commercial considerations which in the long run must overrule all others. ( 3 ) THE "WESTMINSTER" SERIES Town Gas and its Uses for the Production of Light, Heat, and Motive Power. By W. H. Y. Webber, C.E. With 71 Illustrations. List of Contents : The Nature and Properties of Town Gas. The History and Manufacture of Town Gas. The Bye-Products of Coal Gas Manufacture. Gas Lights and Lighting. Practical Gas Lighting. The Cost of Gas Lighting. Heating and Warm- ing by Gas. Cooking by Gas. The Healthfulness and Safety of Gas in all its uses. Town Gas for Power Generation, including Private Electricity Supply. The Legal Relations of Gas Sup- pliers, Consumers, and the Public. Index. The " country," as opposed to the " town," has been defined as " the parts beyond the gas lamps." This book provides accurate knowledge regarding the manufacture and supply of town gas and its uses for domestic and industrial purposes. Few people realize the extent to which this great industry can be utilized. The author has produced a volume which will instruct and interest the generally well informed but not technically instructed reader. Electro-Metallurgy. By J. B. C. Kershaw, F.I.C. With 61 Illustrations. Contents : Introduction and Historical Survey. Aluminium. Production. Details of Processes and Works. Costs. UtiUza- tion. Future of the Metal. Bullion and Gold. ■ Silver Refining Process. Gold Refining Processes. Gold Extraction Processes. Calcium Carbide and Acetylene Gas. The Carbide Furnace and Process. Production. Utilization. Carborundum. Details of Manufacture. Properties and Uses. Copper. Copper Refin- ing. Descriotions of Refineries. Costs. Properties and Utiliza- tion. The Elmore and similar Processes. Electrolytic Extrac- tion Processes. Electro-Metallurgical Concentration Processes. Ferro-alloys. Descriptions of Works. Utilization. Glass and Quartz Glass. Graphite. Details of Process.j Utilization. Iron and Steel. Descriptions of Furnaces and Processes. Yields and Costs. Comparative Costs. Lead. The Salom Process. The Betts Refining Process. The Betts Reduction Process. White Lead Pro- cesses. Miscellaneous Products. Calcium. Carbon Bisulphide. Carbon Tetra-Chloride. Diamantine. Magnesium. Phosphorus. Silicon and its Compounds. Nickel. Wet Processes. Dry Processes. Sodium. Descriptions of Cells and Processes. Tin. Alkaline Processes for Tin Stripping. Acid Processes for Tin Stripping. Salt Processes for Tin Stripping. Zinc. Wet Pro- cesses. Dry Processes. Electro-Thermal Processes. Electro- Galvanizing. Glossary. Name Index. The subject of this volume, the branch of metallurgy which deals with the extraction and refining of metals by aid of electricity, is becoming of great importance. The author gives a brief and clear account of the industrial developments of electro-metallurgy, in lan- guage that can be understood by those whose acquaintance with either ( 4 ) THE "WESTMINSTER" SERIES chemical or electrical science may be but slight. It is a thoroughly pi^actical work descriptive of apparatus and processes, and commends itself to all practical men engaged in metallurgical operations, as well as to business men, financiers, and investors. Radio-Telegraphy. By C. C. F. Monckton, M.I.E.E. With 173 Diagrams and Illustrations. Contents : Preface. Electric Phenomena. Electric Vibrations. Electro-Magnetic Waves. Modified Hertz Waves used in Radio- Telegraphy. Apparatus used for Charging the Oscillator. The Electric Oscillator : Methods of Arrangement, Practical Details. The Receiver : Methods of Arrangement, The Detecting Ap- paratus, and other details. Measurements in Radio-Telegraphy. The Experimental Station at Elmers End : Lodge-Muirhead System. Radio - Telegraph Station at Nauen : Telefunken System. Station at Lyngby : Poulsen System. The Lodge- Muirhead System, the Marconi System, Telefunken System, and Poulsen System. Portable Stations. Radio-Telephony. Ap- pendices : The Morse Alphabet. Electrical Units used in this Book. International Control of Radio-Telegraphy. Index. The startling discovery twelve years ago of what is popularly known as Wireless Telegraphy has received many no less startling additions since then. The official name now given to this branch of electrical practice is Radio-Telegraphy. The subject has now reached a thor- oughly practicable stage, and this book presents it in clear, concise form. The various services for which Radio-Telegraphy is or may be used are indicated by the author. Every stage of the subject is illustrated by diagrams or photographs of apparatus, so that, while an elementary knowledge of electricity is presupposed, the bearings of the subject can be grasped by every reader. No subject is fraught with so manv possibilities of development for the future relationships of the peoples of the world. India-Rubber and its Manufacture^ with Chapters on Gutta-Percha and Balata. By H. L. Terry, F.I.C., Assoc.Inst.M.M. With Illustrations. List of Contents : Preface. Introduction : Historical and General. Raw Rubber. Botanical Origin. Tapping the Trees. Coagulation. Principal Raw Rubbers of Commerce. Pseudo- Rubbers. Congo Rubber. General Considerations. Chemical and Physical Properties. Vulcanization. India-rubber Planta- tions. India-rubber Substitutes. Reclaimed Rubber. Washing and Drying of Raw Rubber. Compounding of Rubber. Rubber Solvents and their Recovery. Rubber Solution. Fine Cut Sheet and Articles made therefrom. Elastic Thread. Mechanical Rubber Goods. Sundry Rubber Articles. India-rubber Proofed Textures. Tyres. India-rubber Boots and Shoes. Rubber for Insulated Wires. Vulcanite Contracts for India-rubber Goods. THE "WESTMINSTER" SERIES The Testing of Rubber Goods. Gutta-Percha. Balata. Biblio- graphy. Index. Tells all about a material which has grown immensely in com- mercial importance in recent years. It has been expressly written for the general reader and for the technologist in other branches of industry. Glass Manufacture. By Walter Rosenhain, Superin- tendent of the Department of Metallurgy in the National Physical Laboratory, late Scientific Adviser in the Glass Works of Messrs. Chance Bros, and Co. With Illustra- tions. Contents: Preface. Delinitions. Physical and Chemical Qualities. Mechanical, Thermal, and Electrical Properties. Transparency and Colour. Raw materials of manufacture. Crucibles and Furnaces for Fusion. Process of Fusion. Processes used in Working of Glass. Bottle. Blown and Pressed. Rolled or Plate. Sheet and Crown. Coloured. Optical Glass : Nature and Properties, Manufacture. Miscellaneous Products. Ap- pendix. Bibliography of Glass Manufacture. Index. quate guide or help to those engaged in glass manufacture itself. For this reason the account of manufacturing processes has been kept as non-technical as possible. In describing each process the object in view has been to give an insight into the rationale of each step, so far as it is known or understood, from the point of view of principles and methods rather than as mere rule of thumb description of manu- facturing manipulations. The processes described are, with the exception of those described as obsolete, to the author's definite know- ledge, in commercial use at the present time. Precious Stones. By W. Goodchild, M.B., B.Ch. With 42 Illustrations. With a Chapter on Artificial Stones. By Robert Dykes. List of Contents : Introductory and Historical. Genesis of Precious Stones. Physical Properties. The Cutting and Polish- ing of Gems. Imitation Gems and the Artificial Production of Precious Stones. The Diamond. Fluor Spar and the Forms of Silica. Corundum, including Ruby and Sapphire. Spinel and Chrysoberyl. The Carbonates and the Felspars. The Pyroxene and Amphibole Groups. Beryl, Cordierite, Lapis Lazuli and the Garnets. Olivine, Topaz, Tourmaline and other Silicates. Phos- phates, Sulphates, and Carbon Compounds. An admirable guide to a fascinating subject. ( 6 ) THE "WESTMINSTER" SERIES Patents, Designs and Trade Marks : The Law and Commercial Usage, By Kenneth R. Swan, B.A. (Oxon.), of the Inner Temple, Barrister-at-Law. Contents : Table of Cases Cited — Part I. — Letters Pateyit. Intro- duction. General. Historical. I., II., III. Invention, Novelty, Subject Matter, and IHility the Essentials of Patentable Invention. IV. Specilication. V. Construction of Specification. VI. Who May Apply for a Patent. VII. Application and Grant. VIII. Opposition. IX. Patent Rights. Legal Value. Commercial Value. X. Amendment. XI. Infringement of Patent. XII. Action for Infringement. XIII. Action to Restrain Threats. XIV. Negotiation of Patents by Sale and Licence. XV. Limita- tions on Patent Right. XVI. Revocation. XVII. Prolonga- tion. XVIII. Miscellaneous. XIX. Foreign Patents. XX. Foreign Patent Laws : United States of America. Germany. France. Table of Cost, etc., of Foreign Patents. Appendix A. — I. Table of Forms and Fees. 2. Cost of Obtaining a British Patent. 3. Convention Countries. Part II. — Copyright in Design. Introduction. I. Registrable Designs. II. Registra- tion. III. Marking. IV. Infringement. Appendix B. — i. Table of Forms and Fees. 2. Classification of Goods. Part III. — Trade Marks. Introduction. I. Meaning of Trade Mark. II. Qualification for Registration. III. Restrictions on Regis- tration. IV. Registration. V. Effect of Registration. VI. Miscellaneous. Appendix C. — Table of Forms and Fees. Indices. I. Patents. 2. Designs. 3. Trade Marks. This is the first book on the subject since the New Patents Act, Its aim is not only to present the existing law accurately and as fully as possible, but also to cast it in a form readily comprehensible to the layman unfamiliar with legal phraseology. It will be of value to those engaged in trades and industries where a knowledge of the patenting of inventions and the registration of trade marks is important. Full information is given regarding patents in foreign countries. The Book; Its History and Development. By Cyril Davenport, V.D., F.S.A. With 7 Plates and 126 Figures in the text. List of Contents : Early Records. Rolls, Books and Book bindings. Paper. Printing. Illustrations. Miscellanea. Leathers. The Ornamentation of Leather Bookbindings without Gold. The Ornamentation of Leather Bookbindings with Gold, Bibliography. Index. The romance of the Book and its development from the rude inscrip- tions on stone to the magnificent de Luxe tomes of to-day have never been so excellently discoursed upon as in this volume. The history of the Book is the history of the preservation of human thought. This work should be in the possession of evey book lover. ( 7 ) Van Nostrand's "Westminster" Series LIST OF NEW AND FORTHCOMING VOLUMES. Timber. By J. R. Baterden, A.MJ.C.E. Steam Engines. By J. T. Rossiter, MJ.E.E., A.M.I.M.E. Electric Lamps. By Maurice Solomon, A.C.GJ., A.M.I.E.E. The Railway Locomotive. By Vaughan Pendred, M.I.Mech.E. Leather. By H. Garner Bennett. Pumps and Pumping Machinery. By James W. ROSSITER, A.M.LM.E. 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