Graham, 1882.) (Both categories: Jullion, | Simple hydrolysis— | 1855. Blitz, 1883. Dahl, | | 1884.) | Products removed from sphere of | | action by combination with base | | and sulphite. (Cross, 1880.) | | | | Oxidation prevented by presence | | of sulphite. | {79} CHAPTER VI. SPECIAL TREATMENT OF VARIOUS FIBRES; BOILERS, BOILING PROCESSES, ETC. We have already, in Chapter V., discussed in a general way the principles upon which the treatment of the various fibres should be based; we now proceed to consider each fibre in detail, giving at the same time such information as is necessary regarding the preliminary treatment of the various fibres and describing the forms of apparatus in which these operations are conducted. We shall consider the fibres in the order of their simplicity of treatment. _Rags_ (Linen and Cotton).—The treatment necessary for rags differs largely with the quality and, of course, with the kind of paper for which they are intended. These different qualities are known in the trade by different names and marks, such for example as the following:—New linen pieces, new cotton pieces, superfines, dark fines, grey linen, sailcloth, seconds, thirds, &c., &c. The two former consist of the cuttings produced in the manufacture of various garments, &c.; not having been worn, they are usually free from dirt, and are, in fact, if bleached, nearly pure cellulose, containing only the starch and other sizing material which has been added in the process of finishing the goods. They may, of course, contain considerable quantities of china clay or other loading material. In purchasing rags, therefore, regard should be had to the probable presence of these bodies. Such rags require only a very slight treatment; in fact, for certain classes of paper they might be used without any preparation. If, as is sometimes the case, the rags are unbleached, a rather more severe boiling is necessary. {80} [Illustration: FIG. 16.]