An extended investigation showed as in the case of the latter that the celluloses themselves are more or less profoundly attacked by the treatment-further that the celluloses isolated from lignocelluloses and other complex raw materials are much 'less pure' than those obtained by the Lange process. Thus, notably in regard to furfural yielding constituents, the latter yield 1-2 p.ct. furfural, whereas specimens of jute cellulose' obtained by the Gabriel process were found to yield 9 to 13 p.ct. furfural.

Cross and Bevan.-Chlorination process yielded in the hands of the authors results confirming the figures given in 'Cellulose' for yield of cellulose. Investigation of the products for yield of furfural, gave 9 p.ct. of this aldehyde showing the presence of celluloses, other than the normal type.

Conclusions.-The subjoined table gives the mean numerical results for yield of end-product or 'cellulose' by the various methods. In the case of the 'celluloses' the results are those of the further action of the several processes on the endproduct of a previous process.

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.

(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 I 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 concen

trated 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 18971900, as evidenced by the series of patents of Frémery and Urban, Pauly, Bronnert, and others. The subject will also be found dealt with on p. 58.

(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 in certain directions, chiefly (1) for preparing webs of cloth required to stand considerable strain, and (2) for producing crêpon effects by local or topical action of the alkali. But the results achieved awakened but a transitory interest, and the matter passed into oblivion; so much so, indeed, that a German patent [No. 30,966] was granted in 1884 to the Messrs. Depouilly for crêpon effects due to the differential shrinkage of fabrics under mercerisation, by processes and treatments long previously described by Mercer. Such effects have had a considerable vogue in recent years, but it was not until the discovery of the lustreing effect resulting from the association of the mercerising actions with the condition of strain or tension of the yarn or fabric that the industry in 'mercerised' goods was started on the lines which have led to the present

colossal development. The merit of this discovery is now generally recognised as belonging to Thomas and Prevost of Crefeld, notwithstanding that priority of patent right belongs to the English technologist, H. A. Lowe.

The author critically discusses the grounds of the now celebrated patent controversy, arising out of the conflict of the claims of German patent 85,564/1895 of the former, and English patent 4452/1890 of the latter. The author concludes that Lowe's specification undoubtedly describes the lustreing effect of mercerising in much more definite terms than that of Thomas and Prevost. These inventors, on the other hand, realised the effect industrially, which Lowe certainly failed to do, as evidenced by his allowing the patent to lapse. As an explanation of his failure, the author suggests that Lowe did not sufficiently extend his observations to goods made. from Egyptian and other long-stapled cottons, in which class only are the full effects of the added lustre obtained.

Following these original patents are the specifications of a number of inventions which, however, are of insignificant moment so far as introducing any essential variation of the mercerising treatment.

The third section of the work describes in detail the various mechanical devices which have been patented for carrying out the treatment on yarn and cloth.

The fourth section deals with the fundamental facts underlying the process and effects summed up in the term 'mercerisation.' These are as follows:

(a) Although all forms of fibrous celluloses are similarly affected by strong alkaline solutions, it is only the Egyptian and other long-stapled cottons-i.e. the goods made from them-which under the treatment acquire the special high lustre which ranks as silky.' Goods made from American cottons acquire a certain finish' and lustre, but the effects