THE RAW MATERIALS.—In former days, paper was manufactured exclusively from rags, either linen or cotton ; but the increased demand for it, for printing and other purposes, has made it absolutely necessary that some more abundant source should be found. Paper is composed chiefly of cellulose, in a more or less purified state, and as this forms the basis or groundwork of all vegetable life, it is obvious that the supply of raw materials is practically unlimited. But as cellulose in nature is found intimately associated with colouring and incrusting matters, the removal of which involves the use of comparatively expensive chemicals, the paper-manufacturer, in fixing his choice on a raw material, must take into consideration not only its first cost, but also the amount and character of such combined substances, and the comparative ease or difficulty with which they can be removed, in order to secure the cellulose in a pure state.
The following list contains the more important materials actually in use for manufacturing paper :—Rags, linen and cotton; flax ; hemp ; esparto or alfa; woods of various kinds ; straw ; old ropes ; jute ; old sacking ; manilla hemp; canes and bamboo; and Adansonia fibre. To these, might be added an almost innumerable list of other substances which are used to a very limited extent. The production and commerce, and in many cases the structure, of the vegetable fibres, will be found described at length in the article on Fibrous Substances, pp. 909-1000. In this article, attention will be confined to the paper-making qualities of the chief materials.
Rags.—Though, strictly speaking, not raw material, the substance of the rags having under gone a purifying treatment before being manufactured, they may conveniently be classed as such here. Rags may be obtained in an almost endless variety, differing according to the locality in which they are gathered. They are generally sent to the paper-maker packed in bale; having been to a certain extent sorted. For trade purposes, rags are divided into a large number of classes or grades, distinguished by various letters. When rags are stored in large quantities,
care should be taken that they are perfectly dry, as, if at all damp, they are liable to fire, from the heat developed by slow decomposition. Nearly all the inorustiug and colouring matters having been removed from the cotton or flax from which the rags are made, in the textile manufacturing processes, it follows that they consist of tolerably pure cellulose, and therefore yield a large percentage of fibre. This, together with the fact that they are readily bleached to a very pure white, the resulting fibre being exceedingly strong, renders them a most valuable material. Alone, they arc used for only the finest qualities of paper, but they are often mixed with inferior fibres to give strength.
Flax.—Raw flax being in great demand for textile purposes, cannot be economically manu factured directly into paper. Such portions, however, as are rejected by the spinner can thus be made use of. (See Fibrous Substances, pp. 964478 ; Linen Manufactures, pp. 1246-1255).
Hemp.—Hernp is generally used only in the form of old ropes, &c. (See Fibrous Substances, pp. 934-8 ; Rope.) Esparto.—T his grass is perhaps, next to rags, the most important material used by paper-makers in this country. The consumption has steadily increased since it was first introduced by Routledge in 1856. Various qualities of esparto are known, the best of which is imported from Spain. Slightly inferior qualities are brought from various districts in N. Africa. (See Fibrous Substances, pp. 978-981.) The amount of fibre in esparto varies according to the locality in which it is grown, Spanish yielding more than any other kind. According to Dr. Hugo Miller, Spanish esparto contains 49.52-50.19 per cent. of cellulose, and African, per cent. This, of course, does not represent the amount of fibre actually obtainable by the manufacturer, a considerable loss occurring during the various processes to which it is subjected. The yield of bleached fibre obtained in practice probably does not much exceed 40 per cent.