Proportions by volume Temperature Heat Heat of Test Test Acetone Water Explosion 80 deg. 134 deg. Deg. Mins. Mins. 20 80 137 3 4 30 70 160 3 4 40 60 180 7 18 No fumes after From 'A' sample. 50 50 187.5 55 100 60 40 187 45 100 70 30 185 45 100 80 20 50 100 92 8 185 50 100 Structure- less powder. " 'B' sample 50 50 183 35 100 " 'C' sample Ordinary service 185 10 41 guncotton

a certain solvent action, and on adding an equal bulk of water, the dissolved nitrate for the most part is precipitated, at the same time that the undissolved but disintegrated and swollen product undergoes further changes in the direction of increase of hardness and density. The product being now collected on a filter, freed from acetone by washing with water and dried, is a hard and dense powder the fineness of which varies according to the attendant conditions of treatment. With the main product in certain cases there is found associated a small proportion of nitrate retaining a fibrous character, which may be separated by means of a fine sieve. On examining such a residue, we found it to contain only 5.6 p.ct. N, and as it was insoluble in strong acetone, it may be regarded as a low nitrate or a mixture of such with unaltered cellulose. Confirming this we found that the product passing through the sieve showed an increase of nitrogen to 13.43 p.ct. from the 13.31 p.ct. in the original. Tested by the heat test (50 minutes) and stability test (no fumes after 100 minutes), we found the products to have the characteristics previously noticed.

It is clear, therefore, that this specifically regulated action of acetone produces the effects (a) of disintegration, and (b) stabilisation. It remains to determine whether the latter effect was due, as might be supposed, to the actual elimination of a compound or group of compounds present in the original nitrate, and to be regarded as the effective cause of instability. It is to be noted first that as a result of the treatment with the diluted acetone and further dilution after the specific action is completed, collecting the disintegrated product on a filter and washing with water, the loss of weight sustained amounts to 3 to 4 p.ct. This loss is due, therefore, to products remaining dissolved in the filtrate—that is to say, in the much diluted acetone. These filtrates are in fact opalescent from the presence of a portion of nitrate in a colloidal (hydrated) form. On distilling off the acetone, a precipitation is determined. The precipitates are nitrates of variable composition, analysis showing from 9 to 12 p.ct. of nitric nitrogen. The filtrate from these precipitates containing only fractional residues of acetone still shows opalescence. On long-continued boiling a further precipitation is determined, the filtrates from which are clear. It was in this final clear filtrate that the product assumed to cause the instability of the original nitrate would be present. The quantity, however, is relatively so small that we have only been able to obtain and examine it as residue from evaporation to dryness. An exhaustive qualitative examination established a number of negative characteristics, with the conclusion that the products were not direct derivatives of carbohydrates nor aromatic compounds. On the other hand the following positive points resulted. Although the original diluted acetone extract was neutral to test papers, yet the residue was acid in character. It contained combined nitric groups, fused below 200 deg. giving off acid vapours, and afterwards burning with a smoky flame. On adding lead acetate to the original clear solution, a well-marked precipitation was determined. The lead compounds thus isolated are characteristic. They have been obtained in various ways and analysed. The composition varies with the character of the solution in which the lead compound is formed. Thus in the opalescent or milky solutions in which a proportion of cellulose nitrate is held in solution or semi-solution by the acetone still present, the lead acetate causes a dense coagulation. The precipitates dried and analysed showed 16-20 p.ct. PbO and 11-9 p.ct. N. It is clear that the cellulose nitrates are associated in these precipitates with the lead salts of the acid compounds in question. When the latter are obtained from clear solutions, i.e. in absence of cellulose nitrates, they contain 60-63 p.ct. PbO and 3.5 p.ct. N (obtained as NO).

In further confirmation of the conclusion from these results, viz. that the nitrocelluloses with no tendency to combine with PbO are associated with acid products or by-products of the ester reaction combining with the oxide, the lead reagent was allowed to react in the presence of 90 p.ct. acetone. Water was added, the disintegrated mass collected, washed with dilute acetic acid, and finally with water. Various estimations of the PbO fixed in this way have given numbers varying from 2 to 2.5 p.ct. Such products are perfectly stable. This particular effect of stabilisation appears, therefore, to depend upon the combination of certain acid products present in ordinary nitrocelluloses with metallic oxides. In order to further verify this conclusion, standard specimens of cellulose nitrates have been treated with a large number of metallic salts under varying conditions of action. It has been finally established (1) that the effects in question are more particularly determined by treatment with salts of lead and zinc, and (2) that the simplest method of treatment is that of boiling the cellulose nitrates with dilute aqueous solutions of salts of these metals, preferably the acetates. The following results may be cited, obtained by boiling a purified 'service' guncotton (sample C) with a 1 p.ct. solution of lead acetate and of zinc acetate respectively. After boiling 60 minutes the nitrates were washed free from the soluble metallic salts, dried and tested.

_________ Heat Test Heat Test at 80 deg. at 134 deg. _____ ___ ___ Original sample C 10 41 Treated with lead acetate 67 45 " zinc " 91 45 _____ ___ ___

In conclusion we may briefly resume the main points arrived at in these investigations.

Causes of instability of cellulose nitrates.—The results of our experiments so far as to the causes of instability in cellulose nitrates may be summed up as follows:—

(1) Traces of free nitrating acids, which can only occur in the finished products through careless manufacture, will undoubtedly cause instability, indicated strongly by the ordinary heat test at 80 deg., and to a less extent by the heat test at 134 deg..

(2) Other compounds exist in more intimate association with the cellulose nitrates causing instability which cannot be removed by exhaustive washing with either hot or cold water, by digestion in cold dilute alkaline solutions such as sodium carbonate, or by extracting with ether, alcohol, benzene, &c.; these compounds, however, are soluble in the solvents of highly nitrated cellulose such as acetone, acetic ether, pyridine, &c., even when these liquids are so diluted with water or other non-solvent liquids to such an extent that they have little or no solvent action upon the cellulose nitrate itself. These solutions containing the bodies causing instability are neutral to test paper, but become acid upon evaporation by heating. (This probably explains the presence of free acid when guncotton is purified by long-continued boiling in water without any neutralising agent being present.)

(3) The bodies causing instability are products or by-products of the original ester reaction, acid bodies containing nitroxy-groups, but otherwise of ill-defined characteristics. They combine with the oxides of zinc or lead, giving insoluble compounds. They are precipitated from their solutions in diluted acetone upon the addition of soluble salts of these metals.

(4) Cellulose nitrates are rendered stable either by eliminating these compounds, or by combining them with the oxides of lead or zinc whilst still in association with cellulose nitrates.

(5) Even the most perfectly purified nitrocellulose will slowly decompose with formation of unstable acid products by boiling for a long time in water. This effect is much more apparent at higher temperatures.

Dense structureless or non-fibrous cellulose nitrates can be industrially prepared (1) by nitrating the amorphous forms of cellulose obtained from its solution as sulphocarbonate (viscose). The cellulose in this condition reacts with the closest similarity to the original fibrous cellulose; the products are similar in composition and properties, including that of instability.

(2) By treating the fibrous cellulose nitrates with liquid solvents of the high nitrate diluted with non-solvent liquids, and more especially water. The optimum effect is a specific disintegration or breaking down of their fibrous structure quite distinct from the gelatinisation which precedes solution in the undiluted solvent, and occurring within narrow limits of variation in the proportion of the diluting and non-solvent liquid—for industrial work the most convenient solution to employ is acetone diluted with about 10 p.ct. of water by volume.

The industrial applications of these results are the basis of English patents 5286 (1898), 18,868 (1898), 18,233 (1898), Luck and Cross (this Journal, 1899, 400, 787).

The structureless guncotton prepared as above described is of quite exceptional character, and entirely distinct from the ordinary fibrous nitrate or the nitrate prepared by precipitation from actual solution in an undiluted solvent.[3] By the process described, the nitrate is obtained at a low cost in the form of a very fine, dense, structureless, white powder of great purity and stability, entirely free from all mechanical impurities. The elimination of these mechanical impurities, and also to a very great extent of coloured compounds contained in the fibrous nitrate, makes the product also useful in the manufacture of celluloids, artificial silk, &c., whilst its very dense form gives it a great advantage over ordinary fibrous guncotton for use in shells and torpedoes, and for the manufacture of gelatinised gunpowders, &c. It can be compressed with ease into hard masses; and experiments are in progress with a view of producing from it, in admixture with 'retaining' ingredients, a military explosive manufactured by means of ordinary black gunpowder machinery and processes.

Manufacture of sporting powder.—The fact that the fibrous structure of ordinary guncotton or other cellulose nitrate can be completely or partially destroyed by treatment with diluted acetone and without attendant solution, constitutes a process of value for the manufacture of sporting powder having a base of cellulose nitrate of any degree of nitration. The following is a description of the hardening process.

'Soft grains' are manufactured from ordinary guncotton or other cellulose nitrate either wholly or in combination with other ingredients, the process employed being the usual one of revolving in a drum in the damp state and sifting out the grains of suitable size after drying. These grains are then treated with diluted acetone, the degree of dilution being fixed according to the hardness and bulk of the finished grain it is desired to produce (J. Soc. Chem. Ind., 1899, 787). Owing to the wide limits of dilution and corresponding effect, the process allows of the production of either a 'bulk' or a 'condensed' powder.

We prefer to use about five litres of the liquid to each one kilo. of grain operated upon, as this quantity allows of the grains being freely suspended in the liquid upon stirring. The grains are run into the liquid, which is then preferably heated to the boiling-point for a few minutes whilst the whole is gently stirred. Under this treatment the grains assume a more or less rounded gelatinous condition according to the strength of the liquid. There is, however, no solution of the guncotton and practically no tendency of the grains to cohere. Each grain, however, is acted upon throughout and perfectly equally. After a few minutes' treatment, water is gradually added, when the grains rapidly harden. They are then freed from acetone and certain impurities by washing with water, heating, and drying. The process is of course carried out in a vessel provided with any means for gentle stirring and heating, and with an outlet for carrying off the volatilised solvent which is entirely recovered by condensation, the grains parting with the acetone with ease.

Stabilising cellulose nitrates.—The process is of especial value in rendering stable and inert the traces of unstable compounds which always remain in cellulose nitrate after the ordinary boiling and washing process. It is of greatest value in the manufacture of collodion cotton used for the preparation of gelatinous blasting explosives and all explosives composed of nitroglycerin and cellulose nitrates. Such mixtures seem peculiarly liable to decomposition if the cellulose nitrate is not of exceptional stability (J. Soc. Chem. Ind., 1899, 787).

EMPLOI DE LA CELLULOSE POUR LA FABRICATION DE FILS BRILLANTS IMITANT LA SOIE.

E. BRONNERT (1) (Rev. Mat. Col., 1900, September, 267).

V. USE OF CELLULOSE IN THE MANUFACTURE OF IMITATIONS OF SILK (LUSTRA-CELLULOSE).

(p. 45) Introduction.—The problem of spinning a continuous thread of cellulose has received in later years several solutions. Mechanically all resolve themselves into the preparation of a structureless filtered solution of cellulose or a cellulose derivative, and forcing through capillary orifices into some medium which either absorbs or decomposes the solvent. The author notes here that the fineness and to a great extent the softness of the product depends upon the dimensions of the capillary orifice and concentration of the solution. The technical idea involved in the spinning of artificial fibres is an old one. Reaumur (2) forecast its possibility, Audemars of Lausanne took a patent as early as 1855 (3) for transforming nitrocellulose into fine filaments which he called 'artificial silk.' The idea took practical shape only when it came to be used in connection with filaments for incandescent lamps. In this connection we may mention the names of the patentees:—Swinburne (4), Crookes, Weston (5), Swan (6), and Wynne and Powell (7). These inventors prepared the way for Chardonnet's work, which has been followed since 1888 with continually increasing success.

At this date the lustra-celluloses known may be divided into four classes.

1. 'Artificial silks' obtained from the nitrocelluloses.

2. 'Lustra-cellulose' made from the solution of cellulose in cuprammonium.

3. 'Lustra-cellulose' prepared from the solution of cellulose in chloride of zinc.

4. 'Viscose silks,' by the decomposition of sulphocarbonate of cellulose (Cross and Bevan).

GROUP 1. The early history of the Chardonnet process is discussed and some incidental causes of the earlier failures are dealt with. The process having been described in detail in so many publications the reader is referred to these for details. [See Bibliography, (1) and (2), (3) and (4).] The denitrating treatment was introduced in the period 1888-90 and of course altogether changed the prospects of the industry; not only does it remove the high inflammability, but adds considerably to softness, lustre, and general textile quality. In Table I will be found some important constants for the nitrocellulose fibre; also the fibre after denitration and the comparative constants for natural silk.

TABLE 1.

_____________ Tenacity Elasticity (grammes) (% elongation) _______ ___ ___ Nitrocellulose according to Chardonnet German Patent No. 81,599 150 23 The same after denitration 110 8 Denitrated fibre moistened with water 25 Nitrocellulose: Bronnert's German Patent No. 93,009 125 28 The same after denitration (dry) 115 13 The same after denitration (wetted) 32 Natural silk 300 18 _______ ___ ___

1. Tenacity is the weight in grammes required to break the thread.

2. Elasticity is the elongation per cent. at breaking.

The numbers are taken for thread of 100 deniers (450 metres of 0.05 grammes = 1 denier). It must be noted that according to the concentration of the solution and variations in the process of denitration the constants for the yarn are subject to very considerable variation.

In regard to the manufacture a number of very serious difficulties have been surmounted. First, instead of drying the nitrated cellulose, which often led to fires, &c., it was found better to take it moist from the centrifugal machine, in which condition it is dissolved (5). It was next found that with the concentrated collodion the thread could be spun direct into the air, and the use of water as a precipitant was thus avoided.

With regard to denitration which is both a delicate and disagreeable operation: none of the agents recommended to substitute the sulphydrates have proved available. Of these the author mentions ferrous chloride (6), ferrous chloride in alcohol (7), formaldehyde (8), sulphocarbonates. The different sulphydrates (9) have very different effects. The calcium compound tends to harden and weaken the thread. The ammonia compound requires great care and is costly. The magnesium compound works rapidly and gives the strongest thread. Investigations have established the following point. In practice it is not necessary to combine the saponification of cellulose ester with complete reduction of the nitric acid split off. The latter requires eight molecules of hydrogen sulphide per one molecule tetranitrocellulose, but with precautions four molecules suffice. It is well known that the denitration is nearly complete, traces only of nitric groups surviving. Their reactions with diphenylamine allow a certain identification of artificial silks of this class. Various other inventors, e.g. Du Vivier (10), Cadoret (11), Lehner (12), have attempted the addition of other substances to modify the thread. These have all failed. Lehner, who persisted in his investigations, and with success, only attained this success, however, by leaving out all such extraneous matters. Lehner works with 10 p.ct. solutions; Chardonnet has continually aimed at higher concentration up to 20 p.ct. Lehner has been able very much to reduce his pressures of ejection in consequence; Chardonnet has had to increase up to pressures of 60 k. per cm. and higher. The latter involves very costly distributing apparatus. Lehner made next considerable advance by the discovery of the fact that the addition of sulphuric acid to the collodion caused increase of fluidity (13), which Lehner attributes to molecular change. Chardonnet found similar results from the addition of aldehyde and other reagents (14), but not such as to be employed for the more concentrated collodions. The author next refers to his discoveries (15) that alcoholic solutions of a number of substances, organic and inorganic, freely dissolve the lower cellulose nitrates. The most satisfactory of these substances is chloride of calcium (16). It is noted that acetate of ammonia causes rapid changes in the solution, which appear to be due to a species of hydrolysis. The result is sufficiently remarkable to call for further investigation. The chloride of calcium, it is thought possible, produces a direct combination of the alcohol with a reactive group of the nitrocellulose. The fluidity of this solution using one mol. CaCl_{2} per 1 mol. tetranitrate (17) reaches a maximum in half an hour's heating at 60 deg.-70 deg.C. The fluidity is increased by starting from a cotton which has been previously mercerised. After nitration there is no objection to a chlorine bleach. Chardonnet has found on the other hand that in bleaching before nitration there is a loss of spinning quality in the collodion. The author considers that the new collodion can be used entirely in place of the ordinary ether-alcohol collodion. With regard to the properties of the denitrated products they fix all basic colours without mordant and may be regarded as oxycellulose therefore. The density of the thread is from 1.5 to 1.55. The thread of 100 deniers shows a mean breaking strain of 120 grammes with an elasticity of 8-12 p.ct. The cardinal defect of these fibres is their property of combination with water. Many attempts have been made to confer water-resistance (18), but without success. Strehlenert has proposed the addition of formaldehyde (19), but this is without result (20). In reference to these effects of hydration, the author has made observations on cotton thread, of which the following table represents the numerical results:

Breaking Strain Mean of 20 experiments

Skein of bleached cotton without treatment 825 Skein of bleached cotton without treatment, but wetted 942 Ditto after conversion into hexanitrate, dry 884 The above, wetted 828 The cotton denitrated from above, dry 529 The cotton denitrated as above and wetted 206

The author considers that other patents which have been taken for spinning nitrocellulose are of little practical account (21) and (22). The same conclusion also applies to the process of Langhans, who proposes to spin solutions of cellulose in sulphuric acid (23) (24) and mixtures of sulphuric acid and phosphoric acid.

GROUP 2. Lustra-cellulose.—Thread prepared by spinning solutions of cellulose in cuprammonium.

This product is made by the Vereinigte Glanzstoff-Fabriken, Aachen, according to a series of patents under the names of H. Pauly, M. Fremery and Urban, Consortium mulhousien pour la fabrication de fils brillants, E. Bronnert, and E. Bronnert and Fremery and Urban (1). The first patent in this direction was taken by Despeissis in 1890 (2). It appears this inventor died shortly after taking the patent (3) The matter was later developed by Pauly (4) especially in overcoming the difficulty of preparing a solution of sufficient concentration. (It is to be noted that Pauly's patents rest upon a very slender foundation, being anticipated in every essential detail by the previous patent of Despeissis.) For this very great care is required, especially, first, the condition of low temperature, and, secondly, a regulated proportion of copper and ammonia to cellulose. The solution takes place more rapidly if the cellulose has been previously oxidised. Such cellulose gives an 8 p.ct. solution, and the thread obtained has the character of an oxycellulose, specially seen in its dyeing properties. The best results are obtained, it appears, by the preliminary mercerising treatment and placing the alkali cellulose in contact with copper and ammonia. (All reagents employed in molecular proportions.) The author notes that the so-called hydrocellulose (Girard) (5) is almost insoluble in cuprammonium, as is starch. It is rendered soluble by alkali treatment.

GROUP 3. Lustra-cellulose prepared by spinning a solution of cellulose in concentrated chloride of zinc.

This solution has been known for a long time and used for making filaments for incandescent lamps. The cellulose threads, however, have very little tenacity. This is no doubt due to the conditions necessary for forming the solution, the prolonged digestion causing powerful hydrolysis (1). Neither the process of Wynne and Powell (2) nor that of Dreaper and Tompkins (3), who have endeavoured to bring the matter to a practical issue, are calculated to produce a thread taking a place as a textile. The author has described in his American patent (4) a method of effecting the solution in the cold, viz. again by first mercerising the cellulose and washing away the caustic soda. This product dissolves in the cold and the solution remains unaltered if kept at low temperature. Experiments are being continued with these modifications of the process, and the author anticipates successful results. The modifications having the effect of maintaining the high molecular weight of the cellulose, it would appear that these investigations confirm the theory of Cross and Bevan that the tenacity of a film or thread of structureless regenerated cellulose is directly proportional to the molecular weight of the cellulose, i.e. to its degree of molecular aggregation (5).

GROUP 4. 'Viscose' silks obtained by spinning solutions of xanthate of cellulose.

In 1892, Cross and Bevan patented the preparation of a new and curious compound of cellulose, the thiocarbonate (1) (2) (3). Great hopes were based upon this product at the time of its discovery. It was expected to yield a considerable industrial and financial profit and also to contribute to the scientific study of cellulose. The later patents of C. H. Stearn (4) describe the application of viscose to the spinning of artificial silk. The viscose is projected into solutions of chloride of ammonium and washed in a succession of saline solutions to remove the residual sulphur impurities. The author remarks that though it has a certain interest to have succeeded in making a thread from this compound and thus adding another to the processes existing for this purpose, he is not of opinion that it shows any advance on the lustra-cellulose (2) and (3). He also considers that the bisulphide of carbon, which must be regarded as a noxious compound, is a serious bar to the industrial use of the process, and for economic work he considers that the regeneration of ammonia from the precipitating liquors is necessary and would be as objectionable as the denitration baths in the collodion process. The final product not being on the market he does not pronounce a finally unfavourable opinion.

The author and the Vereinigte Glanzstoff-Fabriken after long investigation have decided to make nothing but the lustra-cellulose (2) and (3). A new factory at Niedermorschweiler, near Mulhouse, is projected for this last production.

BIBLIOGRAPHY

Introduction

(1) Bull. de la Soc. industr. de Mulhouse, 1900.

(2) Reaumur, Memoire pour servir a l'histoire des insectes, 1874, 1, p. 154.

(3) English Pat. No. 283, Feb. 6, 1855.

(4) Swinburne, Electrician, 18, 28, 1887, p. 256.

(5) Weston (Swinburne), Electrician, 18, 1887, p. 287. Eng. Pat. No. 22866, Sept. 12, 1882.

(6) German Pat. No. 3029. English Pat. No. 161780, April 28, 1884 (Swan).

(7) Wynne-Powell, English Pat. No. 16805, Dec. 22, 1884.

Group I

(1) German Pat No. 38368, Dec. 20, 1885. German Pat. No. 46125, March 4, 1888. German Pat. No. 56331, Feb. 6, 1890. German Pat. No. 81599, Oct. 11, 1893. German Pat. No. 56655, April 23, 1890. French Pat. No. 231230, June 30, 1893.

(2) Industrie textile, 1899, 1892. Wyss-Noef, Zeitschrift fuer angewandte Chemie, 1899, 30, 33. La Nature, Jan. 1, 1898, No. 1283. Revue generale des sciences, June 30, 1898.

(3) German Pat. No. 46125, March 4, 1888. German Pat. No. 56655, April 23, 1890.

(4) Swan, English Pat. 161780, June 28, 1884. See also Bechamp, Dict. de Chimie de Wurtz.

(5) German Pat. No. 81599, Oct 11, 1893.

(6) Bechamp, art. Cellulose, Dict. de Chimie de Wurtz, p. 781.

(7) Chardonnet, addit. March 3, 1897, to the French Pat. 231230, May 30, 1893.

(8) Knofler, French Pat. 247855, June 1, 1895. German Pat. 88556, March 28, 1894.

(9) Bechamp, art. Cellulose, Dict. de Chimie de Wurtz. Blondeau, Ann. Chim. et Phys. (3), 1863, 68, p. 462.

(10) Revue industrielle, 1890, p. 194. German Pat. 52977, March 7, 1889.

(11) French Pat. 256854, June 2, 1896.

(12) German Pat. 55949, Nov. 9, 1889. German Pat. 58508, Sept. 16, 1890. German Pat. 82555, Nov. 15, 1894.

(13) German Pat. 58508, Sept. 16, 1900.

(14) French Pat. 231230, June 30, 1893.

(15) German Pat. 93009, Nov. 19, 1895. French Pat. 254703, March 12, 1896. English Pat. 6858, March 28, 1896.

(16) American Pat. 573132, Dec. 15, 1896.

(17) This proportion is the most advantageous, and furnishes the best liquid collodions that can be spun.

(18) French Pat. 259422, Sept. 3, 1896.

(19) English Pat. 22540, 1896.

(20) Application for German Pat. not granted, 4933 IV. 296, Mar. 16, 1897.

(21) German Pat. 96208, Feb. 10, 1897. Addit. Pat. 101844 and 102573, Dec. 10, 1897.

(22) Oberle et Newbold, French Pat. 25828, July 22, 1896. Granquist, Engl. applic. 2379, Nov. 28, 1899.

(23) German Pat. 72572, June 17, 1891.

(24) Voy. Stern, Ber., 28, ch. 462.

Group II

(1) German Pat. 98642, Dec. 1, 1897 (Pauly). French Pat. 286692, March 10, 1899, and addition of October 14, 1899 (Fremery and Urban). French Pat. 286726, March 11, 1899, and addition of December 4, 1899. German Pat. 111313, March 16, 1899 (Fremery and Urban). English Pat. 18884, Sept. 19, 1899 (Bronnert). English Pat. 13331, June 27, 1899 (Consort. mulhousien).

(2) French Pat. 203741, Feb. 12, 1890.

(3) The actual lapse of this patent is due to the death of Despeissis shortly after it was taken.

(4) Without questioning the good faith of Pauly, it is nevertheless a fact that the original patent remains as a document, and therefore that the value of the Pauly patents is very questionable.

(5) Girard, Ann. Chim. et Phys, 1881 (5), 24, p. 337-384.

Group III

(1) Cross and Bevan, Cellulose, 1895, p. 8.

(2) English Pat. 16805, Dec. 22, 1884.

(3) English Pat. 17901, July 30, 1897.

(4) Bronnert, American Pat. 646799, April 3, 1900.

(5) Cross and Bevan, Cellulose, 1895, p. 12.

Group IV

(1) English Pat. 8700, 1892. German Pat. 70999, Jan. 13, 1893.

(2) English Pat. 4713, 1896. German Pat. 92590, Nov. 21, 1896.

(3) Comptes rendus (loc. cit.). Berichte, c. 9, 65a.

(4) English Pat. 1020, 1898. German Pat. 108511, Oct. 18, 1898.

Artificial Silk—Lustra-cellulose.

C. F. CROSS and E. J. BEVAN (J. Soc. Chem. Ind., 1896, 317).

The object of this paper is mainly to correct current statements as to the artificial or 'cellulose silks' being explosive or highly inflammable (ibid., 1895, 720). A specimen of the 'Lehner' silk was found to retain only 0.19 p.ct. total nitrogen, showing that the denitration is sufficiently complete to dispose of any suggestion of high inflammability.

The product yielded traces only of furfural; on boiling with a 1 p.ct. solution of sodium hydrate, the loss of weight was 9.14 p.ct.; but the solution had no reducing action on Fehling's solution. The product in denitration had therefore reverted completely to a cellulose (hydrate), no oxy-derivative being present.

* * * * *

The authors enter a protest against the term 'artificial silk' as applied to these products, and suggest 'lustra-cellulose.'

DIE KUeNSTLICHE SEIDE-IHRE HERSTELLUNG, EIGENSCHAFTEN UND VERWENDUNG.

CARL SUeVERN, Berlin, 1900, J. Springer.

ARTIFICIAL SILK—ITS PRODUCTION, PROPERTIES, AND APPLICATIONS.

This work of some 130 pages is an important monograph on the subject of the preparation of artificial cellulose threads—so far as the technical elements of the problems involved are discussed and disclosed in the patent literature. The first section, in fact, consists almost exclusively of the several patent specifications in chronological order and ranged under the sub-sections: (a) The Spinning of Nitrocellulose (collodion); (b) The Spinning of other Solutions of Cellulose; (c) The Spinning of Solutions of the Nitrogenous Colloids.

In the second section the author deals with the physical and chemical proportions of the artificial threads.

Chardonnet 'silk' is stated to have a mean diameter of 35 mu, but with considerable variations from the mean in the individual fibres; equally wide variations in form are observed in cross-section. The general form is elliptical, but the surface is marked by deep striae, and the cross-section is therefore of irregular outline. This is due to irregular conditions of evaporation of the solvents, the thread being 'spun' into the air from cylindrical orifices of regulated dimensions. Chardonnet states that when the collodion is spun into alcohol the resultant thread is a perfect cylinder (Compt. rend. 1889, 108, 962). The strength of the fibre is variously stated at from 50-80 p.ct. that of 'boiled off' China tram; the true elasticity is 4-5 p.ct., the elongation under the breaking strain 15-17 p.ct. The sp.gr. is 1.49, i.e. 3-5 p.ct. in excess of boiled off silk.

Lehner 'silk' exhibits the closest similarity to the Chardonnet product. In cross-section it is seen to be more regular in outline, and a round, pseudo-tubular form prevails, due to the conditions of shrinkage and collapse of the fibre in parting with the solvents, and in then dehydrating. The constants for 'breaking strain,' both in the original and moistened condition, for elasticity, &c., are closely approximate to those for the Chardonnet product.

Pauly 'silk'.—The form of the ultimate fibres is much more regular and the contour of the cross-section is smooth. The product shows more resistance to moisture and to alkaline solutions.

Viscose 'silk' is referred to in terms of a communication appearing in 'Papier-Zeitung,' 1898, 2416.

In the above section the following publications are referred to: Chardonnet, 'Compt. rend.,' 1887, 105, 900; and 1889, 108, 962; Silbermann, 'Die Seide,' 1897, v. 2, 143; Herzog, 'Farber-Zeitung,' 1894/5, 49-50; Thiele, ibid. 1897, 133; O. Schlesinger, 'Papier-Zeitung,' 1895, 1578-81, 1610-12.

Action of Reagents upon Natural and Artificial Silks.

1. Potassium hydrate in solution of maximum concentration dissolves the silks proper, (a) China silk on slight warming, (b) Tussah silk on boiling. The cellulose 'silks' show swelling with discolouration, but the fibrous character is not destroyed even on boiling.

2. Potassium hydrate 40 p.ct. China silk dissolves completely at 65 deg.-85 deg.; Tussah silk swells considerably at 75 deg. and dissolves at 100 deg.-120 deg.. The cellulose 'silks' are attacked with discolouration; at 140 deg. (boiling-point of the solution) there is progressive solvent action, but the action is incomplete. The Pauly product is most resistant.

3. Zinc chloride, 40 p.ct. solution. Both the natural silks and lustra-celluloses are attacked at 100 deg., and on raising the temperature the further actions are as follows: China silk is completely dissolved at 110-120 deg.; Tussah silk at 130-135 deg.; the collodion products at 140-145 deg.; the Pauly product was again most resistant, dissolving at 180 deg..

4. Alkaline cupric oxide (glycerin) solution was prepared by dissolving 10 grs. of the sulphate in 100 c.c. water, adding 5 grs. glycerin and 10 c.c. of 40 p.ct. KOH. In this solution the China silk dissolved at the ordinary temperature; Tussah silk and the lustra-celluloses were not appreciably affected.

5. Cuprammonium solution was prepared by dissolving the precipitated cupric hydrate in 24 p.ct. ammonia. In this reagent also the China silk dissolved, and the Tussah silk as well as the lustra-celluloses underwent no appreciable change.

6. An ammoniacal solution of nickel oxide was prepared by dissolving the precipitated hydrated oxide in concentrated ammonia. The China silk was dissolved by this reagent; Tussah silk and the lustra-celluloses entirely resisted its action.

7. Fehling's solution is a solvent of the natural silks, but is without action on the lustra-celluloses.

8. _Chromic acid_—20 p.ct. CrO_{3}—solution dissolves both the natural silks and the lustra-celluloses at the boiling temperature of the solution.

9. Millon's reagent, at the boiling solution, colours the natural silks violet: the lustra-celluloses give no reaction.

10. Concentrated nitric acid attacks the natural silks powerfully in the cold; the lustra-celluloses dissolve on heating.

11. Iodine solution (I in KI) colours the China silk a deep brown, Tussah a pale brown; the celluloses from collodion are coloured at first brown, then blue. The Pauly product, on the other hand, does not react.

12. Diphenylamine sulphate.—A solution of the base in concentrated sulphuric acid colours the natural silks a brown; the collodion 'silks' give a strong blue reaction due to the presence of residual nitro-groups. The Pauly product is not affected.

13. Brucin sulphate in presence of concentrated sulphuric acid colours the natural silks only slightly (brown); the collodion 'silks' give a strong red colouration. The Pauly product again is without reaction.

14. Water.—The natural silks do not soften in the mouth as do the lustra-celluloses.

15. Water of condition was determined by drying at 100 deg.; the following percentages resulted (a). The percentages of water (b) taken up from the atmosphere after forty-three hours' exposure were:

(a) (b) China (raw) silk 7.97 2.24 Tussah silk 8.26 5.00

Lustra-celluloses:

Chardonnet (Besancon) 10.37 5.64 " Spreitenbach 11.17 5.77 Lehner 10.71 5.97 Pauly 10.04 6.94

16. Behaviour on heating at 200 deg..—After two hours' heating at this temperature the following changes were noted:

China silk Much discoloured (brown). Tussah silk Scarcely affected.

Lustra-celluloses:

Chardonnet Converted into a blue-black charcoal, retaining the Lehner form ofthe fibres.

Pauly A bright yellow-brown colouration, without carbonisation.

17. The losses of weight accompanying these changes and calculated per 100 parts of fibre dried at 100 deg. were:

China silk 3.18 Tussah silk 2.95

Lustra-celluloses:

Chardonnet 33.70 Lehner 26.56 Pauly 1.61

18. Inorganic constituents.—Determinations of the total ash gave for the first five of the above, numbers varying from 1.0 to 1.7 p.ct. The only noteworthy point in the comparison was the exceptionally small ash of the Pauly product, viz. 0.096 p.ct.

19. Total nitrogen.—The natural silks contain the 16-17 p.ct. N characteristic of the proteids. The lustra-celluloses contain 0.05-0.15 p.ct. N which in those spun from collodion is present in the form of nitric groups.

The points of chemical differentiation which are established by the above scheme of comparative investigation are summed up in tabular form.

Methods of dyeing.—The lustra-celluloses are briefly discussed. The specific relationship of these forms of cellulose to the colouring matters are in the main those of cotton, but they manifest in the dye-bath the somewhat intensified attraction which characterises mercerised cotton, or more generally the cellulose hydrates.

Industrial applications of the lustra-celluloses are briefly noticed in the concluding section of the book.

FOOTNOTES:

[3] With these products it is easy to observe that they have a definite fusion point 5 deg.-10 deg. below the temperature of explosion.



SECTION III. DECOMPOSITIONS OF CELLULOSE SUCH AS THROW LIGHT ON THE PROBLEM OF ITS CONSTITUTION

UEBER CELLULOSE.

G. BUMCKE und R. WOLFFENSTEIN (Berl. Ber., 1899, 2493).

(p. 54) Theoretical Preface.—The purpose of these investigations is the closer characterisation of the products known as 'oxycellulose' and 'hydracellulose,' which are empirical aggregates obtained by various processes of oxidation and hydrolysis; these processes act concurrently in the production of the oxycelluloses. The action of hydrogen peroxide was specially investigated. An oxycellulose resulted possessing strongly marked aldehydic characteristics. The authors commit themselves to an explanation of this paradoxical result, i.e. the production of a body of strongly 'reducing' properties by the action of an oxidising agent upon the inert cellulose molecule (? aggregate) as due to the hydrolytic action of the peroxide: following Wurster (Ber. 22, 145), who similarly explained the production of reducing sugars from cane sugar by the action of the peroxide.

The product in question is accordingly termed hydralcellulose. By the action of alkalis this is resolved into two bodies of alcoholic (cellulose) and acid ('acid cellulose') characteristics respectively. The latter in drying passes into a lactone. The acid product is also obtained from cellulose by the action of alkaline lye (boiling 30 p.ct. NaOH) and by solution in Schweizer's reagent.

It is considered probable that the cellulose nitrates are hydrocellulose derivatives, and experimental evidence in favour of this conclusion is supplied by the results of 'nitrating' the celluloses and their oxy- and hydro- derivatives. Identical products were obtained.

Experimental investigations.—The filter paper employed as 'original cellulose,' giving the following numbers on analysis:

C 44.56 44.29 44.53 44.56 H 6.39 6.31 6.46 6.42

was exposed to the action of pure distilled H{2}O{2} at 4-60 p.ct. strength, at ordinary temperatures until disintegrated: a result requiring from nineteen to thirty days. The series of products gave the following analytical results:

C 43.61 43.61 43.46 43.89 44.0 43.87 43.92 43.81 H 6.00 6.29 6.28 6.26 6.13 6.27 6.24 6.27

results lying between the requirements of the formulae:

5 C{6}H{10}O{5}.H{2}O and 8 C{6}H{10}O{5}.H{2}O.

Hydrazones were obtained with 1.7-1.8 p.ct. N. Treated with caustic soda solution the hydrazones were dissolved in part: on reprecipitation a hydrazone of unaltered composition was obtained. The original product shows therefore a uniform distribution of the reactive CO- groups.

The hydralcellulose boiled with Fehling's solution reduced 1/12 of the amount required for an equal weight of glucose.

Digested with caustic soda solution it yielded 33 p.ct. of its weight of the soluble 'acid cellulose.' This product was purified and analysed with the following result: C 43.35 H 6.5. For the direct production of the 'acid' derivative, cellulose was boiled with successive quantities of 30 p.ct. NaOH until dissolved. It required eight treatments of one hour's duration. On adding sulphuric acid to the solutions the product was precipitated. Yield 40 p.ct. Analyses:

C 43.8 43.8 43.7 H 6.2 6.2 6.3

The cellulose reprecipitated from solution in Schweizer's reagent gave similar analytical results:

C 43.9 43.8 44.0 H 6.5 6.3 6.4

_Conversion into nitrates._—The original cellulose, hydral- and acid cellulose were each treated with 10 times their weight of HNO_{3} of 1.48 sp.gr. and heated at 85 deg. until the solution lost its initial viscosity.

The products were precipitated by water and purified by solution in acetone from which two fractions were recovered, the one being relatively insoluble in ethyl alcohol. The various nitrates from the several original products proved to be of almost identical composition,

C 32.0 H 4.2 N 8.8

with a molecular weight approximately 1350. The conclusion is that these products are all derivatives of a 'hydralcellulose' 6C{6}H{10}O{5}H{2}O.

FORMATION OF FURFURALDEHYDE FROM CELLULOSE, OXYCELLULOSE, AND HYDROCELLULOSE.

By LEO VIGNON (Compt. rend., 1898, 126, 1355-1358).

(p. 54) Hydrocellulose, oxycellulose, and 'reduced' cellulose, the last named being apparently identical with hydrocellulose, were obtained by heating carefully purified cotton wool (10 grams) in water (1,000 c.c.), with (1) 65 c.c. of hydrochloric acid (1.2 sp.gr.), (2) 65 c.c. of hydrochloric acid and 80 grams of potassium chlorate, (3) 65 c.c. of hydrochloric acid and 50 grams of stannous chloride. From these and some other substances, the following percentage yields of furfuraldehyde were obtained: Hydrocellulose, 0.854; oxycellulose, 2.113; reduced cellulose, 0.860; starch, 0.800; bleached cotton, 1.800; oxycellulose, prepared by means of chromic acid, 3.500. Two specimens of oxycellulose were prepared by treating cotton wool with hydrochloric acid and potassium chlorate (A), and with sulphuric acid and potassium dichromate (B), and 25 grams of each product digested with aqueous potash. Of the product A, 16.20 grams were insoluble in potash, 2.45 grams were precipitated on neutralisation of the alkaline solution, and 6.35 grams remained in solution, whilst B yielded 11.16 grams of insoluble matter, 1.42 grams were precipitated by acid, and 12.42 grams remained in solution. The percentage yields of furfuraldehyde obtained from these fractions were as follows: A, insoluble, 0.86; precipitated, 4.35; dissolved, 1.10. B, insoluble, 0.76; precipitated, 5.11; dissolved, 1.54. It appears, from the foregoing results, that the cellulose molecule, after oxidation, is easily decomposed by potash, the insoluble and larger portion having all the characters of the original cellulose, whilst the soluble portion is of an aldehydic nature, and contains a substance, precipitable by acids, which yields a relatively large amount of furfuraldehyde.

UNTERSUCHUNGEN UeBER DIE OXYCELLULOSE.

O. V. FABER und B. TOLLENS (Berl. Ber., 1899, 2589).

Investigations of Oxycellulose.

(p. 61) The author's results are tersely summed up in the following conclusions set forth at the end of the paper: The oxycelluloses are mixtures of cellulose and a derivative oxidised compound which contains one more atom O than cellulose (cellulose = C_{6}H_{10}O_{5}), and for which the special designation _Celloxin_ is proposed.

Celloxin may be formulated C{8}H{6}O{6} or C{6}H{10}O{6}, of which the former is the more probable.

The various oxycelluloses may be regarded as containing one celloxin group to 1-4 cellulose groups, according to the nature of the original cellulose, and the degree of oxidation to which subjected. These groups are in chemical union.

Celloxin has not been isolated. On boiling the oxycelluloses with lime-milk it is converted into isosaccharinic and dioxybutyric acids. The insoluble residue from the treatment is cellulose.

The following oxycelluloses were investigated:

A. Product of action of nitric acid upon pine wood (Lindsey and Tollens, Ann. 267, 366).—The oxycelluloses contained

1 mol celloxin: {2 mol. cellulose on 6 hours' heating {3 mol. cellulose on 3 hours' heating

with a ratio H : O = 1 : 9 and 1 : 8.7 respectively: they yielded 7 p.ct. furfural.

B. By action of bromine in presence of water and CaCO{3} upon cotton.—Yield, (air-dry) 85 p.ct. Empirical composition C{12}H{20}O{11} = C{6}H{10}O{5}.C{6}H{10}O{6}: yielded furfural 1.7 p.ct.

C. Cotton and nitric acid at 100 deg., two and a half hours (Cross and Bevan).—Yield, 70 p.ct. Composition

4 C{6}H{10}O{5}.C{6}H{8}O{6}

yielded furfural 2.3 p.ct.

D. Cotton and nitric acid at 100 deg. (four hours).—A more highly oxidised product resulted, viz. 3 C{6}H{10}O{5}.C{6}H{8}O{6}: yielded furfural 3.2 p.ct.

By-products of oxidation.—The liquors from B were found to contain saccharic acid: the acid from C and B contained a dibasic acid which appeared to be tartaric acid.

The isolation of (1) isosaccharinic and (2) dioxybutyric acid from the products of digestion of the oxycelluloses with lime-milk at 100 deg. was effected by the separation of their respective calcium salts, (1) by direct crystallisation, (2) by precipitation alcohol after separation of the former.

CELLULOSES, HYDRO- AND OXYCELLULOSES, AND CELLULOSE ESTERS.

L. VIGNON (Bull. Soc. Chim., 1901 [3], 25, 130).

(a) _Oxycelluloses from cotton, hemp, flax, and ramie._—The comparative oxidation of these celluloses, by treatment with HClO_{3} at 100 deg., gave remarkably uniform results, as shown by the following numbers, showing extreme variations: yields, 68-70 p.ct.; hydrazine reaction, N fixed 1.58-1.69; fixation of basic colouring matters (relative numbers), saffranine, 100-200, methylene blue, 100-106. The only points of difference noted were (1) hemp is somewhat more resistant to the acid oxidation; (2) the cotton oxycellulose shows a somewhat higher (25 p.ct.) cupric reduction.

(b) 'Saccharification' of cellulose, cellulose hydrates, and hydrocellulose.—The products were digested with dilute hydrochloric acid six hours at 100 deg., and the cupric reduction of the soluble products determined and calculated to dextrose.

100 grms. of gave reducing products equal to Dextrose

Purified cotton 3.29 " Hydrocellulose 9.70 Cotton mercerised (NaOH 30 deg. B.) 4.39 Cotton mercerised (NaOH 40 deg. B.) 3.51 Cellulose reprecipitated from cuprammonium 4.39 Oxycellulose 14.70 Starch 98.6

These numbers show that cellulose may be hydrated both by mercerisation and solution, without affecting the constitutional relationships of the CO groups. The results also differentiate the cellulose series from starch in regard to hydrolysis.

(c) Cellulose and oxycellulose nitrates.—The nitric esters of cellulose have a strong reducting action on alkaline copper solutions. The author has studied this reaction quantitatively for the esters both of cellulose and oxycellulose, at two stages of 'nitration,' represented by 8.2-8.6 p.ct. and 13.5-13.9 p.ct. total nitrogen in the ester-products, respectively. The results are expressed in terms (c.c.) of the cupric reagent (Pasteur) reduced per 100 grs. compared with dextrose (=17767).

Cellulose maximum nitration (13.5 p.ct. N) 3640 Oxycellulose maximum nitration (13.9 p.ct. N) 3600 Cellulose minimum nitration (8.19 p.ct. N) 3700 Oxycellulose minimum nitration (8.56 p.ct. N) 3620

The author concludes that, since the reducing action is independent of the degree of nitration, and is the same for cellulose and the oxycelluloses, the ester reaction in the case of the normal cellulose is accompanied by oxidation, the product being an oxycellulose ester.

_Products of 'denitration'._—The esters were treated with ferrous chloride in boiling aqueous solution. The products were oxycelluloses, with a cupric reduction equal to that of an oxycellulose directly prepared by the action of HClO_{3}. On the other hand, by treatment with ammonium sulphide at 35 deg.-40 deg. 'denitrated' products were obtained without action on alkaline copper solutions.

OXYCELLULOSES AND THE MOLECULAR WEIGHT OF CELLULOSE.

H. NASTUKOFF (Berl. Ber. 33 [13] 2237).

(p. 61) The author continues his investigations of the oxidation of cellulose. [Compare Bull. Mulhouse, 1892.] The products described were obtained by the action of hypochlorites and permanganates upon Swedish filter paper (Schleicher and Schuell).

4. Oxidation by hypochlorites.—(1) The cellulose was digested 24 hrs. with 35 times its weight of a filtered solution of bleaching power of 4 deg.B.; afterwards drained and exposed for 24 hrs. to the atmosphere. These treatments were then repeated. After washing, treatment with dilute acetic acid and again washing, the product was treated with a 10 p.ct. NaOH solution. The oxycellulose was precipitated from the filtered solution: yield 45 p.ct. The residue when purified amounted to 30 p.ct. of the original cellulose, with which it was identical in all essential properties.

The oxycellulose, after purification, dried at 110 deg., gave the following analytical numbers:

C 43.64 43.78 43.32 43.13 H 6.17 6.21 5.98 6.08

Its compound with phenylhydrazine (loc. cit.) gave the following analytical numbers:

N 0.78 0.96 0.84

(2) The reagents were as in (1), but the conditions varied by passing a stream of carbonic acid gas through the solution contained in a flask, until Cl compounds ceased to be given off. The analysis of the purified oxycellulose gave C 43.53, H 6.13.

(3) The conditions were as in (2), but a much stronger hypochlorite solution—viz. 12 deg.B.—was employed. The yield of oxycellulose precipitated from solution in soda lye (10 p.ct. NaOH) was 45 p.ct. There was only a slight residue of unattacked cellulose. The analytical numbers obtained were:

Oxycellulose C 43.31 43.74 43.69 " H 6.47 6.42 6.51

Phenylhydrazine compound N 0.62 0.81

B. _Oxidation by permanganate_ (KMnO_{4}). (1) The cellulose 16 grms. was treated with 1100 c.c. of a 1 p.ct. solution of KMnO_{4} in successive portions. The MnO_{2} was removed from time to time by digesting the product with a dilute sulphuric acid (10 p.ct. H_{2}SO_{4}). The oxycellulose was purified as before, yield 40 p.ct. Analytical numbers:

Oxycellulose C 42.12 42.9 " H 6.20 6.11

Phenylhydrazine compound N 1.35 1.08 1.21

(2) The cellulose (16 grms.) was digested 14 days with 2500 c.c. of 1 p.ct. KMnO_{4} solution. The purified oxycellulose was identical in all respects with the above: yield 40 p.ct. C 42.66, H 6.19.

(3) The cellulose (16 grms.) was heated in the water-bath with 1600 c.c. of 15 p.ct. H_{2}SO_{4} to which were added 18 grms. KMnO_{4}. The yield and composition of the oxycellulose was identical with the above. It appears from these results that the oxidation with hypochlorites acids 1 atom of O to 4-6 of the unit groups C_{6}H_{10}O_{5}; and the oxidation with permanganate 2 atoms O per 4-6 units of C_{6}H_{10}O_{5}. The molecular proportion of N in the phenylhydrazine residue combining is fractional, representing 1 atom O, i.e. 1 CO group reacting per 4 C_{36}H_{60}O_{31} and 6 C_{24}H_{49}O_{21} respectively, assuming the reaction to be a hydrazone reaction.

Further investigations of the oxycelluloses by treatment with (a) sodium amalgam, (b) bromine (water), and (c) dilute nitric acid at 110 deg., led to no positive results.

By treatment with alcoholic soda (NaOH) the products were resolved into a soluble and insoluble portion, the properties of the latter being those of a cellulose (hydrate).

Molecular weight of cellulose and oxycellulose.—The author endeavours to arrive at numbers expressing these relations by converting the substances into acetates by Schutzenberger's method, and observing the boiling-points of their solution in nitrobenzene.

FERMENTATION OF CELLULOSE

V. OMELIANSKI (Compt. Rend., 1897, 125, 1131-1133).

Pure paper was allowed to ferment in the presence of calcium carbonate at a temperature of 35 deg. for 13 months. The products obtained from 3.4743 grams of paper were: acids of the acetic series, 2.2402 grams; carbonic anhydride, 0.9722 grams; and hydrogen, 0.0138 gram. The acids were chiefly acetic and butyric acid, the ratio of the former to the latter being 1.7 : 1. Small quantities of valeric acid, higher alcohols, and odorous products were formed.

The absence of methane from the products of fermentation is remarkable, but the formation of this gas seems to be due to a special organism readily distinguishable from the ferment that produces the fatty acids. This organism is at present under investigation.

* * * * *

(p. 75) Constitution of Cellulose.—It may be fairly premised that the problem of the constitution of cellulose cannot be solved independently of that of molecular aggregation. We find in effect that the structural properties of cellulose and its derivatives are directly connected with their constitution. So far we have only a superficial perception of this correlation. We know that a fibrous cellulose treated with acids or alkalis in such a way that only hydrolytic changes can take place is converted into a variety of forms of very different structural characteristics, and these products, while still preserving the main chemical characteristics of the original, show when converted into derivatives by simple synthesis, e.g. esters and sulphocarbonates, a corresponding differentiation of the physical properties of these derivatives, from the normal standard, and therefore that the new reacting unit determines a new physical aggregate. Thus the sulphocarbonate of a 'hydrocellulose' is formed with lower proportions of alkaline hydrate and carbon disulphide, gives solutions of relatively low viscosity, and, when decomposed to give a film or thread of the regenerated cellulose, these are found to be deficient in strength and elasticity. Similarly with the acetate. The normal acetate gives solutions of high viscosity, films of considerable tenacity, and when those are saponified the cellulose is regenerated as an unbroken film. The acetates of hydrolysed celluloses manifest a retrogradation in structural and physical properties, proportioned to the degree of hydrolysis of the original.

We may take this opportunity of pointing out that the celluloses not only suggest with some definiteness the connection of the structural properties of visible aggregates—that is, of matter in the mass—with the configuration of the chemical molecule or reacting unit, but supply unique material for the actual experimental investigation of the problems involved. Of all the 'organic' colloids cellulose is the only one which can be converted into a variety of derivative forms, from each of which a regular solid can be produced in continuous length and of any prescribed dimensions. Thus we can compare the structural properties of cellulose with those of its hydrates, nitrates, acetates, and benzoates, in terms of measurements of breaking strain, extensibility, elasticity. Investigations in this field are being prosecuted, but the results are not as yet sufficiently elaborated for reduction to formulae. One striking general conclusion is, however, established, and that is that the structural properties of cellulose are but little affected by esterification and appear therefore to be a function of the special arrangement of the carbon atoms, i.e. of the molecular constitution. Also it is established that the molecular aggregate which constitutes a cellulose is of a resistant type, and undoubtedly persists in the solutions of the compounds.

It may be urged that it is superfluous to import these questions of mass-aggregation into the problem of the chemical constitution of cellulose. But we shall find that the point again arises in attempting to define the reacting unit, which is another term for the molecule. In the majority of cases we rely for this upon physical measurements; and in fact the purely chemical determination of such quantities is inferential. Attempts have been made to determine the molecular weights of the cellulose esters in solution, by observations of depression of solidifying and boiling-points. But the numbers have little value. The only other well-defined compound is the sulphocarbonate. It has been pointed out that, by successive precipitations of this compound, there occurs a continual aggregation of the cellulose with dissociation of the alkali and CS residues and it has been found impossible to assign a limit to the dissociation, i.e. to fix a point at which the transition from soluble sulphocarbonate to insoluble cellulose takes place.

On these grounds it will be seen we are reduced to a somewhat speculative treatment of the hypothetical ultimate unit group, which is taken as of C_{6} dimensions.

As there has been no addition of experimental facts directly contributing to the solution of the problem, the material available for a discussion of the probabilities remains very much as stated in the first edition, pp. 75-77. It is now generally admitted that the tetracetate n [C{6}H{6}O.(OAc){4}] is a normal cellulose ester; therefore that four of the five O atoms are hydroxylic. The fifth is undoubtedly carbonyl oxygen. The reactions of cellulose certainly indicate that the CO- group is ketonic rather than aldehydic. Even when attacked by strong sulphuric acid the resolution proceeds some considerable way before products are obtained reducing Fehling's solution. This is not easily reconcilable with any polyaldose formula. Nor is the resistance of cellulose to very severe alkaline treatments. The probability may be noted here that under the action of the alkaline hydrates there occurs a change of configuration. Lobry de Bruyn's researches on the change of position of the typical CO- group of the simple hexoses, in presence of alkalis, point very definitely in this direction. It is probable that in the formation of alkali cellulose there is a constitutional change of the cellulose, which may in effect be due to a migration of a CO- position within the unit group. Again also we have the interesting fact that structural changes accompany the chemical reaction. It is surprising that there should have been no investigation of these changes of external form and structure, otherwise than as mass effects. We cannot, therefore, say what may be the molecular interpretation of these effects. It has not yet been determined whether there are any intrinsic volume changes in the cellulose substance itself: and as regards what changes are determined in the reacting unit or molecule, we can only note a fruitful subject for future investigation. A priori our views of the probable changes depend upon the assumed constitution of the unit group. If of the ordinary carbohydrate type, formulated with an open chain, there is little to surmise beyond the change of position of a CO- group. But alternative formulae have been proposed. Thus the tetracetate is a derivative to be reckoned with in the problem. It is formed under conditions which preclude constitutional changes within the unit groups. The temperature of the main reaction is 30 deg.-40 deg., the reagents are used but little in excess of the quantitative proportions, and the yields are approximately quantitative. If now the derivative is formed entirely without the hydrolysis the empirical formula C{6}H{6}O.(OAc){4} justifies a closed-ring formula for the original viz. COCH{2}; and the preference for this formula depends upon the explanation it affords of the aggregation of the groups by way of CO-CH{2} synthesis.

The exact relationship of the tetracetate to the original cellulose is somewhat difficult to determine. The starting-point is a cellulose hydrate, since it is the product obtained by decomposition of the sulphocarbonate. The degree of _hydrolysis_ attending the cycle of reactions is indicated by the formula 4 C_{6}H_{10}O_{5}.H_{2}O. It has been already shown that this degree of hydrolysis does not produce molecular disaggregation. If this hydrate survived the acetylation it would of course affect the empirical composition, i.e. chiefly the carbon percentage, of the product. It may be here pointed out that the extreme variation of the carbon in this group of carbohydrate esters is as between C_{14}H_{20}O_{10} (C = 48.3 p.ct.) and C_{14}H_{18}O_{9} (C = 50.8 p.ct.) i.e. a tetracetate of C_{6}H_{12}O_{6} and C_{6}H_{10}O_{5} respectively. In the fractional intermediate terms it is clear that we come within the range of ordinary experimental errors, and to solve this critical point by way of ultimate analysis must involve an extended series of analyses with precautions for specially minimising and quantifying the error. The determination of the acetyl by saponification is also subject to an error sufficiently large to preclude the results being applied to solve the point. While, therefore, we must defer the final statement as to whether the tetracetate is produced from or contains a partly hydrolysed cellulose molecule, it is clear that at least a large proportion of the unit groups must be acetylated in the proportion C_{6}H_{6}O.(OAc)_{4}.

It has been shown that by the method of Franchimont a higher proportion of acetyl groups can be introduced; but this result involves a destructive hydrolysis of the cellulose: the acetates are not derivatives of cellulose, but of products of hydrolytic decomposition.

It appears, therefore, that with the normal limit of acetylation at the tetracetate the aggregation of the unit groups must depend upon the CO- groups and a ring formula of the general form COCH_{2} is consistent with the facts.

Vignon has proposed for cellulose the constitutional formula

O CH O [CHOH]{3} / CH{2}-CH/

with reference to the highest nitrate, and the decomposition of the nitrate by alkalis with formation of hydroxypyruvic acid. While these reactions afford no very sure ground for deductions as to constitutional relationships, it certainly appears that, if the aldose view of the unit group is to be retained, this form of the anhydride contains suggestions of the general tendency of the celluloses on treatment with condensing acids to split off formic acid in relatively large quantity [Ber. 1895, 1940]; the condensation of the oxycelluloses to furfural; the non-formation of the normal hydroxy-dicarboxylic acids by nitric acid oxidations. Indirectly we may point out that any hypothesis which retains the polyaldose view of cellulose, and so fails to differentiate its constitution from that of starch, has little promise of progress. The above formula, moreover, concerns the assumed unit group, with no suggestion as to the mode of aggregation in the cellulose complex. Also there is no suggestion as to how far the formula is applicable to the celluloses considered as a group. In extending this view to the oxycelluloses, Vignon introduces the derived oxidised group

CHO.(CHOH)_{3}.CH . CO _O_

—of which one is apportioned to three or four groups of the cellulose previously formulated: these groups in condensed union together constitute an oxycellulose.

These views are in agreement with the experimental results obtained by Faber and Tollens (p. 71). They regard the oxycelluloses as compounds of 'celloxin' C{6}H8{O}{6} with 1-4 mols. unaltered cellulose; and the former they particularly refer to as a lactone of glycuronic acid. But on boiling with lime they obtain dioxybutyric and isosaccharinic acids; both of which are not very obviously related to the compounds formulated by Vignon. We revert with preference to a definitely ketonic formula, for which, moreover, some farther grounds remain to be mentioned. In the systematic investigation of the nitric esters of the carbohydrates (p. 41) Will and Lenze have definitely differentiated the ketoses from the aldoses, as showing an internal condensation accompanying the ester reaction. Not only are the OH groups taking part in the latter consequently less by two than in the corresponding aldoses, but the nitrates show a much increased stability. This would give a simple explanation of the well-known facts obtaining in the corresponding esters of the normal cellulose. We may note here that an important item in the quantitative factors of the cellulose nitric ester reaction has been overlooked: that is, the yield calculated to the NO{3} groups fixed. The theoretical yields for the higher nitrates are

Yield p.ct. N p.ct. of cellulose of nitrate Pentanitrate 169 12.7 Hexanitrate 183 14.1

From such statistics as are recorded the yields are not in accordance with the above. There is a sensible deficiency. Thus Will and Lenze record a yield of 170 p.ct. for a product with 13.8 p.ct. N, indicating a deficiency of about 10 p.ct. As the by-products soluble in the acid mixture are extremely small, the deficiency represents approximately the water split off by an internal reaction. In this important point the celluloses behave as ketoses.

In the lignocelluloses the condensed constituents of the complex are of well-marked ketonic, i.e. quinonic, type. In 'nitrating' the lignocelluloses this phenomenon of internal condensation is much more pronounced (see p. 131). As the reaction is mainly confined to the cellulose of the fibre, we have this additional evidence that the typical carbonyl is of ketonic function. It is still an open question whether the cellulose constituents of the lignocelluloses are progressively condensed—with progress of 'lignification'—to the unsaturated or lignone groups. There is much in favour of this view, the evidence being dealt with in the first edition, p. 180. The transition from a cellulose-ketone to the lignone-ketone involves a simple condensation without rearrangement; from which we may argue back to the greater probability of the ketonic structure of the cellulose. We must note, however, that the celluloses of the lignocelluloses are obtained as residues of various reactions, and are not homogeneous. They yield on boiling with condensing acids from 6 to 9 p.ct. furfural. It is usual to regard furfural as invariably produced from a pentose residue. But this interpretation ignores a number of other probable sources of the aldehyde. It must be particularly remembered that laevulose is readily condensed (a) to a methylhydroxyfurfural

C_{6}H_{1}O_{6} - 3H_{2}O = C_{6}H_{6}O_{3} = C_{5}(OH).H_{2}.(CH_{3})O_{2}

and (b) by HBr, with further loss of OH, as under:

C_{6}H_{12}O_{6} - 4H_{2}O + HBr = C_{5}H_{3}(CH_{2}Br)O

and generally the ketoses are distinguished from the aldoses by their susceptibility to condensation. Such condensation of laevulose has been effected by two methods: (a) by heating the concentrated aqueous solution with a small proportion of oxalic acid at 3 atm. pressure [Kiermayer, Chem. Ztg. 19, 100]; (b) by the action of hydrobromic acid (gas) in presence of anhydrous ether; the actual compound obtained being the omega-brommethyl derivative [Fenton, J. Chem. Soc. 1899, 423].

This latter method is being extended to the investigation of typical celluloses, and the results appear to confirm the view that cellulose may be of ketonic constitution.

The evidence which is obtainable from the synthetical side of the question rests of course mainly upon the physiological basis. There are two points which may be noted. Since the researches of Brown and Morris (J. Chem. Soc. 1893, 604) have altered our views of the relationships of starch and cane sugar to the assimilation process, and have placed the latter in the position of a primary product with starch as a species of overflow and reserve product, it appears that laevulose must play an important part in the elaboration of cellulose. Moreover, A. J. Brown, in studying the cellulosic cell-collecting envelope produced by the Bacterium xylinum, found that the proportion of this product to the carbohydrate disappearing under the action of the ferment was highest in the case of laevulose. These facts being also taken into consideration there is a concurrence of suggestion that the typical CO group in the celluloses is of ketonic character. That the typical cotton cellulose breaks down finally under the action of sulphuric acid to dextrose cannot be held to prove the aldehydic position of the carbonyls in the unit groups of the actual cellulose molecule or aggregate.

We again are confronted with the problem of the aggregate and as to how far it may affect the constitution of the unit groups. That it modifies the functions or reactivity of the ultimate constituent groups we have seen from the study of the esters. Thus with the direct ester reactions the normal fibrous cellulose (C_{6}H_{16}O_{5}) yields a monoacetate, dibenzoate, and a trinitrate respectively under conditions which determine, with the simple hexoses and anhydrides, the maximum esterification, i.e. all the OH groups reacting. If the OH groups are of variable function, we should expect the CO groups _a fortiori_ to be susceptible of change of function, i.e. of position within the unit groups.

But as to how far this is a problem of the constitution or phases of constitution of the unit groups or of the aggregate under reaction we have as yet no grounds to determine.

The subjoined communication, appearing after the completion of the MS. of the book, and belonging to a date subsequent to the period intended to be covered, is nevertheless included by reason of its exceptional importance and special bearing on the constitutional problem above discussed.

THE ACTION OF HYDROGEN BROMINE ON CARBOHYDRATES.[4]

H. J. H. FENTON and MILDRED GOSTLING (J. Chem. Soc., 1901, 361).

The authors have shown in a previous communication (Trans., 1898, 73, 554) that certain classes of carbohydrates when acted upon at the ordinary temperature with dry hydrogen bromide in ethereal solution give an intense and beautiful purple colour.[5] It was further shown (Trans., 1899, 75, 423) that this purple substance, when neutralised with sodium carbonate and extracted with ether, yields golden-yellow prisms of omega-brommethylfurfural,

CH:C.CH_{2}Br O CH:C.CHO.

This reaction is produced by laevulose, sorbose, cane sugar, and inulin, an intense colour being given within an hour or two. Dextrose, maltose, milk sugar, galactose, and the polyhydric alcohols give, if anything, only insignificant colours, and these only after long standing. The authors therefore suggested that the reaction might be employed as a means of distinguishing these classes of carbohydrates, the rapid production of the purple colour being indicative of ketohexoses, or of substances which produce these by hydrolysis.

By relying only on the production of the purple colour, however, a mistake might possibly arise, owing to the fact that xylose gives a somewhat similar colour after standing for a few hours. Hence, the observations should be confirmed by isolation of the crystals of brommethylfurfural. No trace of this substance is obtained from the xylose product.

In order to identify the substance, the ether extract, after neutralisation, is allowed to evaporate to a syrup, and crystallisation promoted either by rubbing with a glass rod, or by the more certain and highly characteristic method of 'sowing' with the most minute trace of omega-brommethylfurfural, when crystals are almost instantly formed. These are recrystallised from ether, or a mixture of ether and light petroleum, and further identified by the melting-point (59.5-60.5 deg.), and, if considered desirable, by estimation of the bromine.

It is now found, so reactive is the bromine atom in this compound, that the estimation may be accurately made by titration with silver nitrate according to Volhard's process, the crystals for this purpose being dissolved in dilute alcohol:

0.1970 gram required 10.5 c.c. _N_/10 AgNO_{3}. Br = 42.63 p.ct., calculated 42.32 p.ct.

This method of applying hydrogen bromide in ethereal solution is, of course, unsuitable for investigations where a higher temperature has to be employed, or where long standing is necessary, since, under such circumstances, the ether itself is attacked. Wishing to make investigations under these conditions, the authors have tried several solvents, and, at present, find that chloroform is best suited to the purpose. In each of the following experiments, 10 grms. of the substance were covered with 250 c.c. of chloroform which had been saturated at 0 deg. with dry hydrogen bromide. The mixture was contained in an accurately stoppered bottle, firmly secured with an iron clamp, and heated in a water-bath to about the boiling temperature for two hours. After standing for several hours, the mixture was treated with sodium carbonate (first anhydrous solid, and afterwards a few drops of strong solution), filtered, and the solution dried over calcium chloride. Most of the chloroform was then distilled off, and the remaining solution allowed to evaporate to a thick syrup in a weighed dish.

The product was then tested for omega-brommethylfurfural by 'sowing' with the most minute trace of the substance, as described above. It was then warmed on a water-oven, kept in a vacuum desiccator over solid paraffin, and the weight estimated. When necessary, the product was recrystallised from ether, and further identified by the tests mentioned. The following results were obtained:

Weight of crude residue. Swedish filter paper 3.0 crystallised at once by 'sowing.' Ordinary cotton 3.3 " " Mercerised cotton 2.1 " " Straw cellulose[6] 2.3 " " Laevulose 2.2 " " Inulin 1.3 " " Potato starch 0.37 " " Cane sugar 0.85 " " Dextrose 0.33 uncrystallisable. Milk sugar 0.37 " Glycogen 0.34 " Galactose 0.34 "

The products from dextrose, milk sugar, and galactose absolutely refused to crystallise even when extracted with ether and again evaporated, or by 'sowing,' stirring, &c.

The glycogen product deposited a very small amount of crystalline matter on standing, but the quantity was too minute for examination; moreover, it refused altogether to crystallise in contact with the aldehyde. It may fairly be stated, therefore, that these last four substances give absolutely negative results as regards the formation of omega-brommethylfurfural; if any is formed, its quantity is altogether too small to be detected.

The specimen of starch examined was freshly prepared from potato, and purified by digestion for twenty-four hours each with N/10 KOH, N/4 HCl, and strong alcohol; it was then washed with water and allowed to dry in the air. It will be seen that this substance gave a positive result, but that the yield was extremely small, and might yet be due to impurity. Considering the importance of the behaviour of starch, for the purpose of drawing general conclusions from these observations, it was thought advisable to make further experiments with specimens which could be relied upon, and also to investigate the behaviour of dextrin. This the authors have been enabled to do upon a series of specimens specially prepared by C. O'Sullivan, and thus described by him:

1. Rice starch, specially purified by the permanganate method.

2. Wheat starch " " "

3. Oat starch, contains traces of oil, washed with dilute KOH and dilute HCl.

4. Pea starch, first crop, washed with alkali, acid (HCl), and strong alcohol.

5. Natural dextrin, D = 3.87, alpha_{D} = 194.7; K = 0.95, (c 2.628).

6. alpha-Dextrin, C equation purified without fermentation, 30 precipitations with alcohol (Trans., 1879, 35, 772).

The examination of these specimens was conducted on a smaller scale, but under the same conditions as before, one gram of the substance being treated with 12.5 c.c. of the saturated chloroform solution and heated in sealed tubes for two hours as above. The results were as follows:

Weight of crude residue. 1. Rice starch 0.046 crystallised at once by 'sowing.' 2. Wheat starch 0.044 " " 3. Oat starch 0.049 " " 4. Pea starch 0.064 " " 5. Natural dextrin 0.088 " " 6. alpha-Dextrin 0.055 " "

The results may therefore be summarised as follows:—Treated under these particular conditions all forms of cellulose give large yields of omega-brommethylfurfural, some varieties giving as much as 33 per cent. Laevulose, inulin, and cane sugar give yields varying from 22 to 8.5 per cent.; various starches give small yields (average about 4.5 per cent.); and dextrins 5 to 8 per cent., whereas dextrose, milk sugar, and galactose give, apparently, none at all.

The yields represent the solid crystalline residue; this when purified by recrystallisation gives, probably, about three-quarters of its weight of pure crystals. (In the case of dextrose, &c., the yields represent the weight of syrup.)

These numbers, however, by no means represent the maximum yields obtainable, owing to the comparatively slight solubility of hydrogen bromide in chloroform. The process was conducted in the above manner only for the sake of uniform comparison. The ether method previously described gives much larger yields; for example, 12 grms. of inulin treated with only 60 c.c. of the saturated ether gave 2.5 grms. of substance. For the purpose of obtaining larger yields, other methods are being investigated.

The facts recorded above, taken in conjunction with those given in our previous communications, appear to point definitely to the following general conclusions. First, that the various forms of cellulose contain one or more groups or nuclei identical with that contained in laevulose, and that such groups constitute the main or essential part of the molecule. Secondly, that similar groupings are contained in starches and dextrins, but that the proportion of such groupings represents a relatively small part of the whole structure.

The nature of this grouping is, according to the generally accepted constitution of laevulose, the six-carbon chain with a ketonic group:

C.C.C.C.C.C . O

But the results might, on the other hand, be considered indicative of the anhydride or 'lacton' grouping, which Tollens suggested for laevulose:

C.C.C.C.C.C / / . O

The latter very simply represents the formation of omega-brommethylfurfural from laevulose,[7]

O - H H OH.C -C -C -C C -CH{2}.OH H{2} OH OH OH H

giving

H H HC.C:C.C:C.CH_{2}Br / , O / O

although by a little further 'manipulation' of the symbols the change could, of course, be represented by reference to the ketonic formula.

The Ketonic Constitution of Cellulose.

C. F. CROSS and E. J. BEVAN (J. Chem. Soc., 1901, 366).

In this paper the authors discuss more fully the theoretical bearings of the observations of Fenton and Gostling, the two papers being simultaneously communicated. The paper is mainly devoted to a review of the antecedent evidence, chemical and physiological, and to a general summing up in favour of the view that cellulose is a polyketose (anhydride).

* * * * *

(p. 79) Composition of the Seed Hair of Eriodendron (Anf.)—Some interest attaches to the results of an analytical investigation which we have made of this silky floss. There is little doubt that cotton is entirely exceptional in its characteristics: both in structure and chemical composition it fails to show any adaptation to what we may regard as the more obvious functions of a seed hair—which certainly do not demand either structural strength or chemical resistance. The following numbers determined for the kapok differentiate it widely from the cottons:

Ash, 1.3; moisture, 9.3; alkaline hydrolysis (loss) (a) 16.7, (b) 21.8. Cellulose, by chlorination, &c., 71.1.

In reacting with chloride it shows the presence of unsaturated groups, similar to the lignone of the woods. This was confirmed by a well-marked reaction with ferric ferricyanide with increase of weight due to the fixation of the blue cyanide.

But the most characteristic feature is the high yield of furfural on boiling with condensing acids. The following numbers were determined:

Total furfural from original fibre 14.84 In residue from alkali hydrolysis 11.5 In cellulose isolated by Cl method 10.4

Treated with sulphuric acids of concentration, (a) 92.1 grs. H{2}SO{4} per 100 c.c., (b) 105.8 grs. per 100 c.c., the fibres dissolve, and diluted immediately after complete solution it was resolved into

(a) (b)

Reprecipitated fraction 68.7 43.7 Soluble fraction yielding furfural 13.2 14.3

By these observations it is established that the furfuroids are of the cellulose type and behave very much as the furfuroids of the cereal celluloses.

This group of seed hairs invites exhaustive investigation. The furfuroid constituents are easily isolated, and as they constitute at least one-third of the fibre substance it is especially from this point of view that they invite study.

RECHERCHES SUR L'OXYCELLULOSE.

L. VIGNON.

Resume of investigations (1898-1900) of Oxycellulose, published as a brochure (Rey, Lyon, 1900).

(a) A typical oxycellulose prepared from cotton cellulose by the action of HClO{3} (HCl + KClO{3}) in dilute solution at 100 deg. for one hour gave the following numbers:

C H O Elementary composition 43.55 6.03 50.42

Oxycellulose Original cellulose Analysis by Lange's method Soluble in KOH (at 180 deg.) 87.6 12.0 Insoluble in KOH (at 180 deg.) 12.4 88.0

Oxycellulose Original cellulose Heat of combustion 4124-4133 4190-4224 Heat evolved in contact with 50 times wt.} normal KOH per 100 grms. } 1.3 cal. 0.74 cal.

Oxycellulose Cellulose Absorption of colouring } Saffranine 0.7 0.0 matters at 100 deg. per 100 grms. } Methylene blue 0.6 0.2

(b) Yield of furfural from cellulose, oxy- and hydro-cellulose.—From the hydrocelluloses variously prepared the author obtains 0.8 p.ct. furfural; from bleached cotton 1.8 p.ct.; and from the oxycelluloses variously prepared 2.0-3.5 p.ct. The 'furfuroid' is relatively more soluble in alkaline solutions (KOH) in the cold. The insoluble residue is a normal cellulose.

(c) _Nitrates of cellulose, oxy- and hydro-cellulose._—Treated with the usual acid mixture (H_{2}SO_{4} 3 p., HNO_{3} 1 p.) under conditions for maximum action, the resulting esters showed uniformly a fixation of 11.0 NO_{2} groups per unit mol. of C_{24}. The oxycellulose nitrate was treated directly with dilute solution of potassium hydrate in the cold. From the products of decomposition the author obtained the osazone of hydroxypyruvic acid [Will, Ber. 24, 400].

(d) Osazones of the oxycelluloses.—Oxycelluloses prepared by various methods are found to fix varying proportions of phenylhydrazine (residue), viz. from 3.4-8.5 p.ct. of the cellulose derivative reacting, corresponding with, i.e. calculated from, the nitrogen determined in the products (0.87-2.2 p.ct.). The reaction is assumed to be that of osazone formation.

The author has also established a relation between the phenylhydrazine fixed and the furfural which the substance yields on boiling with condensing acids. This is illustrated by the subjoined series of numbers:

Phenylhydrazine Furfural Fixed p.ct. formed p.ct. Cotton (bleached) 1.73 1.60 Oxycellulose (HClO{3}) 7.94 2.09 " (HClO) 3.37 1.79 " (CrO{3}) (1) 7.03 3.00 " (CrO{3}) (2) 7.71 3.09 " (CrO{3}) (3) 8.48 3.50

(e) _Constitution of cellulose and oxycellulose._—The results of these investigations are generalised as regards cellulose (C_6) by the constitutional formula

CH CH{2} / (CHOH){3} O CH O .

The oxycelluloses contain the characteristic group

COH / (CHOH)_{3} CH—CO / O

in union with varying proportions of residual cellulose.

QUANTITATIVE SEPARATION OF CELLULOSE-LIKE CARBOHYDRATES IN VEGETABLE SUBSTANCES.

WILHELM HOFFMEISTER (Landw. Versuchs-Stat., 1897, 48, 401-411).

To separate the hemicelluloses, celluloses, and the constituents of lignin without essential change, the substance, after being freed from fat, is extracted with dilute hydrochloric acid and ammonia, and the residue frequently agitated for a day or two with 5-6 p.ct. caustic soda solution. It is then diluted, the extract poured off, neutralised with hydrochloric acid, treated with sufficient alcohol, and the hemicellulose filtered, dried, and weighed. The residue from the soda extract is washed on a filter with hot water, and extracted with Schweizer's reagent.

When the final residue (lignin) is subjected to prolonged extraction with boiling dilute ammonia (a suitable apparatus is described, with sketch) until the ammonia is no longer coloured, a residue is obtained which mostly dissolves in Schweizer's reagent, and on repeating the process the residue is found to consist largely of mineral matter. The dissolved cellulose-like substances often contain considerable amounts of pentosanes.

According to the nature of the substance, the extraction with ammonia may take weeks, or months, or even longer; the ammonia extracts of hard woods (as lignum vitae) and of cork are dark brown, and give an odour of vanilla when evaporated down. The residues, which are insoluble in water, but redissolve in ammonia, have the properties of humic acids. Other vegetable substances, when extracted, yielded, besides humic acids, a compound, C_{6}H_{7}O_{2}, soluble in alcohol and chloroform, but insoluble in water, ether, and benzene; preparations from different sources melted between 200 deg. and 210 deg..

FOOTNOTES:

[4] The original paper is reproduced with slight alterations.

[5] This purple colour would appear to be due to a highly dissociable compound of omega-brommethylfurfural with hydrogen bromide. The aldehyde gives yellow or colourless solutions in various solvents, which are turned purple by a sufficient excess of hydrogen bromide. Dilution, or addition of water, at once discharges the colour.

[6] Other forms of cellulose were also examined—for example, pinewood cellulose—and the substances separated from solution as thiocarbonate (powder and film). All of these gave good yields of omega-brommethylfurfural.

[7] The change is empirically represented as

C_{6}H_{12}O_{6} + HBr - 4H_{2}O = C_{6}H_{5}O_{2}Br.



SECTION IV. CELLULOSE GROUP, INCLUDING HEMICELLULOSES AND TISSUE CONSTITUENTS OF FUNGI

VERSUCHE ZUR BESTIMMUNG DES GEHALTS EINIGER PFLANZEN UND PFLANZENTEILE AN ZELLWANDBESTANDTEILEN AN HEMICELLULOSEN UND AN CELLULOSE.

A. KLEIBER (Landw. Vers.-Stat., 1900, 54, 161).

ON THE DETERMINATION OF CELL-WALL CONSTITUENTS, HEMICELLULOSES AND CELLULOSE IN PLANTS AND PLANT TISSUES.

In a preliminary discussion the author critically compares the results of various of the methods in practice for the isolation and estimation of cellulose. The method of F. Schulze [digestion with dil. HNO{3} with KClO{3}—14 days, and afterwards treating the product with ammonia, &c.] is stated to be the 'best known' (presumably the most widely practised); W. Hoffmeister's modification of the above, in which the nitric acid is replaced by hydrochloric acid (10 p.ct. HCl) is next noted as reducing the time of digestion from 14 days to 1-2 days, and giving in many cases higher yields of cellulose. The methods of treating with the halogens, viz. bromine water (H. Mueller), chlorine gas (Cross and Bevan), and chlorine water, are dismissed with a bare mention, apparently on the basis of the conclusions of Suringar and Tollens (q.v.). The method of Lange, the basis of which is a 'fusion' with alkaline hydrates at 180 deg., and the modified method of Gabriel, in which the 'fusion' with alkali takes place in presence of glycerin, are favourably mentioned.

These methods were applied to a range of widely different raw materials to determine, by critical examination of the products, both as regards yield and composition, what title these latter have to be regarded as 'pure cellulose.'

This portion of the investigation is an extension of that of Suringar and Tollens, these latter confining themselves to celluloses of the 'normal' groups, i.e. textile and paper-making celluloses. The present communication is a study of the tissue and cell-wall constituents of the following types:—

1. Green plants of false oat grass (Arrhenatherium, E.). 2. Green plants of lucerne (Medicago sativa). 3. Leaves of the ash (Fraxinus). 4. Leaves of the walnut (Juglans). 5. Roots of the purple melic grass (Molinia caerulea). 6. Roots of dandelion (Taraxacum officinale). 7. Roots of comfrey. 8. Coffee berries. 9. Wheat bran.

These raw materials were treated for the quantitative estimation of cellulose by the method of Lange (b), Hoffmeister (c), and Schulze (d), and the numbers obtained are referred for comparison to the corresponding yields of 'crude fibre' (Rohfaser) by the standard method (a).