Beyond all doubt, paper has played an important part in transmitting human knowledge and in preserving civilization and its heritage from generation to generation. Before paper existed, it was not possible for instruction to spread and become general. It is therefore no exaggeration to say that paper is the great instrument that has eased the spread of learning and culture among mankind, and that it is one of the cornerstones of our modern civilization.
Paper has an ancient history. The Chinese knew how to make it from silk, and in the British Museum there is a Chinese manuscript dating back to the year 25 A.D...
The Arabs, however, made great advances in the art of its manufacture, for they managed to substitute cheap cotton for rare silk. This work of theirs was a great step forward.
Paper manufacture today relies on wood as its basic source and raw material; it therefore requires countries where extensive forests grow and where an effective system of afforestation exists, so that the trees cut down can be replaced with new ones. It is nevertheless possible to produce certain kinds of paper from hemp, rice husks, straw, and linen threads. Yet however its kinds and sources may differ, paper always consists of "cellulose" fibers (fibres de cellulose). Cellulose is an organic substance found in all plants: cotton contains about 95 percent of it, and wood about 40 percent.
The kinds of paper differ not so much according to the source of the wood as according to the method by which they are made. There is, for example, newsprint, whose manufacture is comparatively simple; there is glossy, shining paper; there is writing paper; and there is stiffened paper, "cardboard," and the paper used for making bags and for wrapping goods, etc...
Since it is not possible to take in the methods of making all these
kinds, I shall content myself with giving the details of the method followed in making the ordinary paper we use for writing or for printing books, merely touching on the manufacture of a few other kinds at the end of the article.
The first step in making paper is to cut the wood into small pieces, no one of which exceeds a centimeter or a centimeter and a half in thickness. This is accomplished by means of large wheels fitted with sharp steel blades. After the cut
ting operation the wood passes over a sieve to remove whatever sawdust clings to it; then the small wooden pieces are placed in large vessels in readiness for cooking, to separate the cellulose from the other woody substances, which make up about 60 percent of the weight of the wood. To achieve this end, the wood chips are mixed with a 10 percent solution of natron — that is, a solution composed in the proportion of 10 grams of natron to 90 grams of water — and the whole is placed in the special vessel; the temperature is then raised high for six hours, under a pressure equal to about 15 kilos to the square centimeter. At the end of the six hours the non-cellulose woody substances have dissolved in the natron solution, leaving the cellulose behind, since it is insoluble in that solution.
There is another method that leads to the same end. It consists, in brief, of mixing the small wood
chips with a solution containing a gas called sulfur dioxide (bi-oxide de Soufre) in place of the natron. To obtain this sulfurous solution, sulfur is burned within closed vessels, sealed except for tubes at their top; the burning of the sulfur yields the gas referred to, which passes through the tubes that carry it to the wood-cooking vessel, where it mixes with the water to form the desired sulfurous solution. The temperature is then raised likewise, under
a pressure like the first, except that the cooking lasts ten hours instead of six.
Whether the natron solution or the sulfur-gas solution is used, the cellulose is separated by these two operations from the other woody substances and remains in the vessel in the form of a gray-colored paste. It is then washed with hot water to remove whatever natron or sulfurous matter still clings to it. But its gray color makes it as yet unfit for use; it is therefore bleached by means of a substance resembling Javel water (Eau de Javelle), made by causing chlorine gas to react with slaked lime, which yields a white powder inclining to gray, called bleaching powder (Poudre de blanchissage). When this powder is mixed with water and the cellulose paste, it removes the foreign colors and
The making of paper