Researches on Cellulose | Page 9

| 95.63 | 78.17 | 79.77 | -- Swedish filter paper | 96.58 | -- | 84.76 | -- | -- Ordinary filter paper | 98.17 | 93.39 | 86.58 | -- | -- Cotton ('wool') | 98.38 | 89.98 | 63.96 | 67.88 | -- Jute | -- | -- | 57.93 | 71.64 | 75.27 Purified wood | -- | -- |{49.27 | -- | -- | | |{46.56 | | Raw wood | 47.60 | -- |{40.82 | -- | -- | | |{38.87 | | --------------------------------------------------------------------------
The final conclusion drawn from the results is that none of the processes fulfil the requirements of an ideal method. Those which may be carried out in a reasonably short time are deficient in two directions: (1) they yield a 'cellulose' containing more or less oxycellulose; (2) the celluloses themselves are attacked under the conditions of treatment, and the end product or cellulose merely represents a particular and at the same time variable equilibrium, as between the resistance of the cellulose and the attack of the reagents employed; this attack being by no means confined to the non-cellulose constituents. Schulze's method appears to give the nearest approximation to the 'actual cellulose' of the raw material.
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(p. 8) ~SOLUTIONS OF CELLULOSE~--(1) ~ZINC CHLORIDE.~--To prepare a homogeneous solution of cellulose by means of the neutral chloride, a prolonged digestion at or about 100° with the concentrated reagent is required. The dissolution of the cellulose is not a simple phenomenon, but is attended with hydrolysis and a certain degree of condensation. The latter result is evidenced by the formation of furfural, the former by the presence of soluble carbohydrates in the solution obtained by diluting the original solution and filtering from the reprecipitated cellulose. The authors have observed that in carefully conducted experiments cotton cellulose may be dissolved in the reagent, and reprecipitated with a loss of only 1 p.ct. in weight. This, however, is a 'net' result, and leaves undetermined the degree of hydration of the recovered cellulose as of hydrolysis of the original to groups of lower molecular weights. Bronnert finds that a previous hydration of the cellulose--e.g. by the process of alkaline mercerisation and removal of the alkali by washing--enables the zinc chloride to effect its dissolution by digestion in the cold. (U.S. patent, 646,799/1900. See also p. 59.)
Industrial applications.--(a) Vulcanised fibre is prepared by treating paper with four times its weight of the concentrated aqueous solution (65-75° B.), and in the resulting gelatinised condition is worked up into masses, blocks, sheets, &c., of any required thickness. The washing of these masses to remove the zinc salt is a very lengthy operation.
To render the product waterproof the process of nitration is sometimes superadded [D.R.P. 3181/1878]. Further details of manufacture are given in Prakt. Handbuch d. Papierfabrikation, p. 1703 [C. Hofmann].
(b) Calico-printing.--The use of the solution as a thickener or colour vehicle, more especially as a substitute for albumen in pigment styles, was patented by E. B. Manby, but the process has not been industrially developed [E.P. 10,466/1894].
(c) Artificial silk.--This is a refinement of the earlier applications of the solution in spinning cellulose threads for conversion into carbon filaments for electrical glow-lamps. This section will be found dealt with on p. 59.
(p. 13) (2) ~Cuprammonium solution.~--The application of the solution of cellulose in cuprammonium to the production of a fine filament in continuous length, 'artificial silk,' has been very considerably studied and developed in the period 1897-1900, as evidenced by the series of patents of Fremery and Urban, Pauly, Bronnert, and others. The subject will also be found dealt with on p. 58.
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(p. 15) ~Reactions of cellulose with iodine.~--In a recent paper, F. Mylius deals with the reaction of starch and cellulose with iodine, pointing out that the blue colouration depends upon the presence of water and iodides. In absence of the latter, and therefore in presence of compounds which destroy or absorb hydriodic acid--e.g. iodic acid--there results a brown addition product. The products in question have the characteristics of solid solutions of the halogen. (Berl. Ber. 1895, 390.)
(24) ~Mercerisation~--Notwithstanding the enormous recent developments in the industrial application of the mercerising reaction, there have been no noteworthy contributions to the theoretical aspects of the subject. The following abstract gives an outline of the scope of an important technical work on the subject.
DIE MERCERISATION DER BAUMWOLLE.
PAUL GARDNER (Berlin: 1898. J. Springer).
~THE MERCERISATION OF COTTON.~
This monograph of some 150 pages is chiefly devoted to the patent literature of the subject. The chemical and physical modifications of the cotton substance under the action of strong alkaline lye, were set forth by Mercer in 1844-5, and there has resulted from subsequent investigations but little increase in our knowledge of the fundamental facts. The treatment was industrially developed by Mercer