Jute Benzoates.—In preparing the jute for treatment it was boiled in alkaline solution (1 per cent. NaOH), washed with water and dilute acid, again washed, dried, and weighed.

In the ester reaction the reagents were employed in the proportion C₁₂H₁₈O₉: 3NaOH: 2C₆H₅COCl. A series of quantitative experiments gave yields of 126-130 p.ct. of benzoate [calculated for monobenzoate 134 p.ct.].

The results were confirmed by ultimate analysis. The monobenzoate therefore represents a maximum, and this molecular proportion is one-half of that observed with the normal cellulose, calculated to the same unit.

Localisation of Benzoyl Group.—The entrance of the ester group affects the typical colour reactions of the lignocellulose, which are fainter. The ferric ferricyanide reaction almost disappears. The lignone group is unaffected, and combines with chlorine as in the original. The lignone chloride is removed by sodium sulphite solution, and the residue is a cellulose benzoate. The loss of weight due to the elimination of the lignone was 12.7 p.ct. Calculating per 100 of the original lignocellulose this becomes 16. These statistics further confirm the localisation of the benzoyl group in the cellulose residue. It is to be noted that the presence of the benzoyl group renders the cellulose more resistant to hydrolytic actions. Thus, to bring out this fact more prominently, we may calculate the yield of residual cellulose benzoate p.ct. of original jute, and we find it 109 p.ct. Taking a maximum proportion for original cellulose—viz. 85—this benzoate represents a yield of 129 p.ct., as against the theoretical for a monobenzoate, 132 p.ct.

Furfural Numbers.—The percentage of furfural obtained by boiling with HCl of 1.06 sp.gr. was 3.02 and 3.29 in separate determinations. Calculating to the original lignocellulose, the percentage, 4.21, indicates a considerable loss of the furfural-yielding constituent. The effect was also apparent in the cellulose (benzoate) isolated by chlorination &c., the percentage being 1.39 p.ct., and calculated to the original jute benzoate 1.59 p.ct. Under the conditions adopted in dissolving away the chlorinated lignone the original non-benzoated lignocellulose would have yielded a cellulose giving 6 to 7 p.ct. furfural.

Since the benzoyl group is hardly calculated to produce a constitutional change affecting the furfural constants, it was necessary to examine the effect of the preliminary alkaline treatment, and the change in the furfuroid group was in fact localised in this reaction. It was found that, on washing the alkali from the mercerised jute, and further purifying the residue, this latter yielded only 4.2 p.ct. furfural [3.4 p.ct. on original fibre]. The alkaline solution and washings were acidified and distilled from 10 p.ct. HCl, yielding an additional 3.6 p.ct. calculated to the original lignocellulose. By treatment with the concentrated alkali, therefore, the furfuroid of the original lignocellulose undergoes little change, but is selectively dissolved. This point is under further investigation.

(p. 132) Acetylation of Lignocelluloses.—Acetates are readily formed by boiling the lignocelluloses with acetic anhydride. The derivatives obtained from jute are only generally mentioned in the 1st edition (p. 132). A further study of the reactions in regard to special points has led to some more definite results. The yields of product by the ordinary and simple process are 114-115 p.ct. But on analysing the product an important discrepancy is revealed.

For the saponification we employ a solution of sodium ethylate in the cold. The following numbers were obtained:

The derivative is approximately a diacetate, and on the assumption of a simple ester reaction the yield should be 127 p.ct. Assuming that the difference of 13 p.ct. is due to loss of water by internal condensation, it appears that for each acetyl group entering, 2 mol. H₂O are split off.

The jute acetate showed the normal reaction with chlorine, and the lignone chloride was dissolved by treatment with sodium sulphite solution. The fibrous residue was colourless. It proved to be a cellulose acetate. The following numbers were obtained on saponification:

The interpretation of these numbers appears to be this: in the original reaction with the lignocellulose it is the cellulose residue which is acetylated, and at the same time condensed. The cellulose residue which undergoes condensation is not of the normal constitution, since the normal cellulose is acetylated without condensation (see p. 41). On saponification a portion of the cellulose, in again combining with water, is hydrolysed to soluble products. The lignone group as it exists in the lignocellulose has no free OH groups, and probably no free aldehydic groups such as would react with the anhydride. Such groups may, however, be originally present, and may take part in the internal condensations which have been shown to occur. The furfural constants of the lignocellulose are unaffected by the acetylation and condensation. The hygroscopic moisture of the product is lowered from 10-11 p.ct. in the original to 4.5 p.ct. The ferric ferricyanide reaction is inhibited by the disappearance of the reactive groups, upon which this curious and characteristic phenomenon depends (1st ed.).

Acetylation of Benzoates.—The cellulose dibenzoate (C₁₂ basis) and the jute monobenzoate were acetylated under comparative conditions The results were as follows:

From these results it would appear that the number of acetyl groups entering the benzoates is the same as with the unbenzoylated fibres, the benzoyl has no influence upon the hydroxyls as against the acetyl. At the same time the internal condensation noticed in the acetylation of the jute appears not to occur in the case of the benzoate.

Nitric Esters.—The numbers resulting from the quantitative study of the ester reaction and product (1st ed. p. 133) show a very large divergence of the yield of product from that which would be calculated from its composition (N p.ct.) on the assumption that the ester reaction is simple. We have repeated the results, and find with a yield of 145 p.ct. that the product contains 11.8 p.ct. N.

The reaction

C₁₂H₁₈O₉ + 4HNO₃ - 4H₂O

gives a tetranitrate with 11.5 p.ct. N and a yield of 159 p.ct. The ester reaction, therefore, is not simple. There are two sources of the loss of weight. The first of these is evident from the occurrence of certain secondary reactions which result in the solution of a certain proportion of the fibre substance in the acid mixture. To determine this quantitatively we have devised a suitable variation of the method of combustion with chromic acid (1st ed.).

The variation is required to meet the difficulty occasioned by the tension of the nitric acid and products of deoxidation. The mixed acids (10 c.c.), containing the organic by-products in solution, are carefully diluted in a small flask with an equal volume of water, preventing rise of temperature. Nitrous fumes are evolved during the dilution. Strong sulphuric acid (15 c.c.) is now added, and the residue of nitrous fumes expelled by a current of air, agitating the contents of the flask from time to time. The combustion with CrO₃ is then proceeded with in the ordinary way. The gases evolved are measured (total volume) and calculated to C present in the form of products derived from the lignocellulose; and, assuming that this contains 47 p.ct. C, we may express the result approximately in terms of the fibre substance. The method was controlled by blank experiments, in which citric acid was taken as a convenient carbon compound for combustion. The C found was 34.9 p.ct. as against 34.3 p.ct. calculated. By this method we find that with maximum yields of nitrate at 143-145 p.ct. the organic matter in solution in the acid mixture amounted to 4.9 to 5.3 p.ct. of the original lignocellulose.

Introducing this quantity as a correction of the yield of nitrate in the original reaction, we must express the 143 parts as obtained from 95 of fibre substance instead of 100.

The yield per molecule C₁₂H₁₈O₉ (= 306) is therefore 462, whereas for a tetranitrate formed by a simple ester reaction the yield should be 486. The difference (24) represents 1.5 mol. H₂O split off by internal condensation.

The correction for total N is relatively small, raising it from 11.5 to 12.2, which remains in close agreement with the experimental numbers.

Monobenzoate.—Treated with the acid mixture yields a mixed nitrate. The yield is 130 p.ct., and the product contains 7.6 p.ct. O.NO₂ nitrogen. These numbers approximate to those required for reaction with 4HNO₃ groups, three of the residues entering the cellulose, and one (as NO₂) the benzene ring of the substituting group. For such a reaction the calculated numbers are: Yield 144 p.ct.; O.NO₂ nitrogen 7.1 p.ct.

The experimental numbers require correcting for the amount of loss in the form of products soluble in the acid mixture, viz. 7.6 p.ct.; but they remain within the range of the experimental errors sufficiently to show that the benzoyl group limits the number of OH groups taking part in the ester reaction to three. The corrected yield per 1 mol. of jute benzoate (410) is 576, as against the calculated 590 for 4HNO₃ reacting. A loss of 1H₂O per molecule by internal condensation is therefore indicated.

Denitration.—The removal of the nitric groups from the esters is effected by digestion with ammonium sulphide. But the reactions are by no means simple. There is considerable hydrolysis of the lignocellulose to soluble products. Thus the tetranitrate yields only 46.4 of denitrated fibre in place of the calculated 66. The product is a cellulose, yielding only 0.5 per cent. furfural. The hydrolysed by-products, moreover, when freed from sulphur and distilled from hydrochloric acid, yielded only an additional 2.5 p.ct. furfural, calculated to the original lignocellulose.

These statistics confirm the evidence that the ester reaction is not simple. Such changes take place in the lignone-β-cellulose complex that they revert, not to their original form, but to soluble derivatives of different constitution. The mixed nitrate from the benzoate is denitrated to a cellulose amidobenzoate, which confirms the localisation of a nitro-group in the benzoyl residue.

(p. 157) General Characteristics of the Lignocelluloses.—Later investigations have somewhat modified and simplified our views of the constitution of the typical lignocellulose (jute), so far as this can be dealt with by the statistics of its more important decompositions (original, pp. 157-161).

Cellulose.—There is little doubt that the furfural-yielding groups of the original are isolated in the form of the β-cellulose. Tollens emphasises this fact in his studies of cellulose-estimation methods. We had previously shown (original, p. 159) that the yield of furfural is not affected by the chlorination, but it appears from our numbers that only 50 p.ct. of these groups remain in the isolated cellulose, the residue undergoing hydrolysis to soluble compounds. In a carefully regulated hydrolysis following the chlorination it appears that the furfuroids are almost entirely conserved in the form of a cellulose.

Moreover, an investigation of the products dissolved by sodium sulphite solution from the chlorinated fibre has shown that they are practically free from furfuroids. This enables us to exclude the furfural-yielding groups from the lignone complex. At the same time, through our later studies of the hydroxyfurfurals, it is certain that these products are represented in the fibre substance and probably in the lignone complex.

Chlorination Statistics.—It has been pointed out by a correspondent—to whom we express our indebtedness—that we have made a mistake in calculating the proportion of lignone from the ratio of the Cl combining with the fibre substance or lignocellulose (p.ct), to that of the Cl present in the isolated lignone chloride (p.ct.). The lignocellulose combines with chlorine in the ratio 100: 8, but the lignone chloride containing 26.7 of chlorine means that, neglecting the hydrogen substituted, 73 of lignone combine with the 27 of chlorine approximately. On the uniform percentage basis the calculated proportion of lignone would be 8/37, or a little over 20 p.ct.

In regard to the proportion of hydration attending the resolution, we have shown on constitutional grounds that this must be relatively small. Assuming approximately the formula C₁₉H₂₂O₉ for the lignone residue as it exists in combination, and the anhydride formula for the cellulose, these revised statistics now appear, as regards the carbon contents of the lignocellulose:

These conclusions are in accordance with the experimental facts, and, taken together with the new evidence we have accumulated from a study of the lignocellulose esters, we may sum up the constitutional points as follows: The lignocellulose is a complex of

The lignone contains but little hydroxyl. The celluloses are in condensed hydroxyl union with the lignone, but the combination occurs by complexes of relatively large molecular weight.

DIE CHEMIE DER LIGNOCELLULOSEN—EIN NEUER TYPUS.

W. C. Hancock and O. W. Dahl (Berl. Ber., 1895, 1558).

Chemistry of Lignocelluloses—A New Type.

The stem of the aquatic Æschynomene aspera offers an exceptional instance of structural modification to serve the special function of a 'float,' 1 grm. of substance occupying an apparent volume of 40-50 c.c. This pith-like substance is morphologically a true wood (De Bary), and the author's investigations now establish that it is in all fundamental points of chemical composition a lignocellulose, although from its colour reactions it has been considered by botanists to be a cellulose tissue containing a proportion of lignified cells. Thus the main tissue is stained blue by iodine in presence of hydriodic acid (1.5 s.g.), and the colour is not changed on washing. The ordinary lignocelluloses are stained a purple brown changed to brown on washing. The reactions with phloroglucol and with aniline salts, characteristic of these compounds, is only faintly marked in the main tissue, though strongly in certain individual cells.

The following quantitative determinations, however, establish the close similarity of the product to the typical lignocelluloses:

Elementary Analysis.—C 46.55, H 6.7. Furfural 11.6 p.ct., of which there remained in the residue from alkaline hydrolysis (71 p.ct.) 8.0, i.e. about 70 p.ct. The distribution of the furfuroids is therefore not affected by the alkaline treatment.

Chlorination.—The substance (after alkaline hydrolysis) takes up 16.9 p.ct. Cl, of which approximately one-half is converted into hydrochloric acid.

Methoxyl.—O.CH₃ estimated = 2.9 p.ct.

Ferric Ferricyanide Reaction.—Increase of weight due to blue cyanide fixed (1) 75 p.ct., (2) 96 p.ct. Ratio, Fe: CN = 1: 2, 4.

Hydroxyl Reactions.—In the formation of nitric esters and in the sulphocarbonate reaction the substance gave results similar to those obtaining for the jute fibre.

These results establish the general identity of this peculiar product of plant life with the lignocelluloses, at the same time that they show that certain of the colour reactions supposed to characterise the lignocelluloses are due to by-products which may or may not be present.

(p. 172) Composition of Elder Pith.—In a systematic investigation of the celluloses in relation to function we shall have to give special attention to the parenchymatous tissues of all kinds. These are, for structural reasons, not easily isolated, for which reason and their generally 'inferior' functions they do not present themselves to chemical observation in the same obvious way as do their fibrous relatives. The pith of the elder, however, is readily obtained in convenient masses, and a preliminary investigation of the entire tissue has established the following points:

The reactions of the tissue are in all respects those of the lignocelluloses.

Composition.—Ash, 2.2 p.ct.; moisture in air-dry state, 12.3 p.ct. Alkaline hydrolysis (loss): (a) 14.77, (b) 17.84. Cellulose (yield), 52.33 p.ct. Nitrate-reaction complicated by secondary reactions and yields low, 90.95 p.ct. Sulphocarbonate reaction: Resists the treatment, less than 10 p.ct. passes into solution.

Furfural.—The original tissue yields 7.13 p.ct.; the residue from alkaline hydrolysis (b) 5.40 p.ct.

This tissue is, therefore, a lignocellulose having the chemical characteristics typical of the group, but of less resistance to hydrolytic actions.

The investigation will be prosecuted in reference to the cause of differentiation in this latter respect. Probably the pectocelluloses are represented in the tissue.

The Insoluble Carbohydrates of Wheat (grain).

H. C. Sherman (J. Amer. Chem. Soc., 1897, 291).

(p. 171) This is a study of the constituents of the cell-walls of wheat grain. Bran was taken as the most convenient form of the raw material, being freed from starch by treatment with malt extract, and further treated (1) with cold dilute ammonia, (2) cold dilute soda lye (2 p.ct. NaOH), and (3) boiling 0.1 p.ct. NaOH. The product retained only 1.25 p.ct. proteids, and yielded 15.62 p.ct. furfural.

Acid Hydrolysis.—The product was boiled 30 mins. with dilute acid (1.25 p.ct. H₂SO₄), and the solution boiled until the Fehling test showed no further increase of monoses. At the limit the reducing power of the dissolved carbohydrates was 91.3 p.ct., that of dextrose. Converted into osazones the analysis showed them to be pure pentosazones. The hemicellulose of wheat is, therefore, according to the author, pure pentosane.

Residue.—This was a lignocellulose yielding 11.5 p.ct. furfural. It was subjected to a series of treatments with ferric ferricyanide, and the proportion of Prussian blue fixed was determined by increase of weight, viz. from 10 p.ct. to 47 p.ct. according to the conditions. The results confirmed those of Cross and Bevan first obtained with the typical lignocellulose (jute).

Chlorination.-The residue was boiled with dilute alkali, washed, and exposed to chlorine gas. The resulting lignone chloride was isolated by solution in alcohol, &c. It yielded 26.7 p.ct. Cl on analysis. In this and its properties it appeared to be identical with the product isolated by Cross and Bevan from jute, with the empirical formula C₁₉H₁₈Cl₄O₉.

Cellulose was isolated from the residue by three of the well-known methods, and the following comparative numbers are noteworthy:

The author remarks: 'It is evident no one feature can be urged as a criterion in judging between the methods, but all must be taken into consideration. Such a comparison shows the superiority of the chlorination method.'

The cellulose is not of the normal (cotton) type, since on treatment with sulphuric acid it dissolves with considerable discolouration, but only to the extent of about 80 per cent. The dissolved monoses converted into osazones were found to consist of hexoses only. The cellulose treated with caustic soda solution (5 p.ct. NaOH) in the cold yielded 20 p.ct. of its weight of soluble constituents, but as the residue yielded 3.34 p.ct. furfural the attack of the alkali is by no means confined to the furfuroids.

Animal Digestion of the Constituents of Bran.—Observations on a steer fed upon wheat bran only established the following percentage digestion of the several constituents:

JOURNAL OF THE IMPERIAL INSTITUTE

(Research Department, Vols. 1-2, 1895-6).

(p. 109) In this journal appear a series of notices of the results of analyses of vegetable fibres by the method described in 'Report on Miscellaneous Fibres' (Col. Ind. Exhibition Reports, p. 368) [C. F. Cross]. These investigations deal with the following subjects:

1895. p. 29 Various Indian Fibres—more particularly Sida.
(a) 118 (a) Fibres from Victoria; (b) SpecialAnalyses ofSamples of Jute; (c) Paper-making Fibres from S. Australia.
202      Fibres from Victoria.
287      Fibres from Victoria.
366      Sisal from Trinidad.
373      Rope-fibres from Grenada.
(b) 398 Report of Experiments on Indian Jute (1).
435}    Fifth and Sixth Report on Australian Fibres.
473}
1896. 68 Hibiscus and Abroma Fibres.
104-5    Hibiscus, Urena, and Crotalaria Fibres.
141      Indian Sisal
(c) 182-3 Report of Experiments on Indian Jute (2).
264      Sanseviera from Assam.

From the above we may draw the general conclusion that the scheme of investigation has been found in practice to answer its main purpose, viz. to afford such numerical constants as determine industrial values. In illustration we may cite (a) the results of analyses of specially selected samples of jute, from which it will be seen that there is a close concordance of value as ordinarily determined from external appearance, with the chemical constants as determined in the laboratory.

A useful series of experiments, initiated by the Institute, is that noted under (b) and (c) above.

(1) To ascertain the quality of the fibre extracted from the plant at different stages of growth, quantities of 400 lbs. of the stalks were cut at successive stages and the fibre isolated after steeping 14-20 days. The fibre was shipped to England and chemically investigated, with the following results:

It will be thus seen that there are no changes of any essential kind in the chemical composition of the bast fibre throughout the life-history of the plant, confirming the conclusion that the 'incrustation' view of lignification is consistent only with the structural features of the changes, and so far as it has assumed the gradual overlaying of a cellulose fibre with the lignone substance it is not in accordance with the facts.

Examination of the samples from the point of view of textile quality showed a superiority of No. 1 in fineness, softness, and strength; from this stage there is observed a progressive deterioration, but the No. 4 sample (which was taken at the usual period of cutting) is superior to No. 5.

In a further series of experiments (c) the jute was subjected to certain chemical treatments immediately after the separation of the fibre from the plant. These consisted in steeping (1) in solution of sodium carbonate, as well as of plant ashes, and (2) in sulphite of soda, the purpose of the treatments being to modify or arrest the changes which take place in the fibre when press-packed in bales for shipment. The samples were shipped from India under the usual conditions and examined soon after arrival. It was found that the chemical treatments had produced but small changes in chemical composition of the fibre-substance. The sulphite treatment was the more marked in influence, somewhat lowering the cellulose and nitration constants. The conclusion drawn from the results was that they afford no prospect of any useful modification, i.e. improvement of the textile quality of the fibre by any chemical treatments such as could be applied to the fibre on the spot before drying for press-packing and shipment.

The other matters investigated in the Institute laboratory and reported on as indicated above are rather of commercial significance, and contributed no points of moment to the chemistry of cellulose.

OBSERVATIONS ON SOME OF THE CHEMICAL SUBSTANCES IN THE TRUNKS OF TREES.

F. H. Storer (Bull. Bussey Inst., 1897, 386).

(p. 172) An examination of the outer and inner wood and of the bark of the grey birch, at different seasons of the year, gave the following yields of furfural p.ct. on the dry substance:

The paper contains the results of treating the woods and various vegetable products with hydrolysing agents in order of intensity: (a) Malt-extract at 60°C., (b) boiling dilute HCl (1.0 p.ct. HCl), and (c) boiling dilute HCl (2.5 p.ct.). The residues were found to yield considerable proportions of furfural. The following numbers are typical:

The proportion of pentosanes (furfuroids) removed, i.e. hydrolysed by boiling with hydrochloric acid of 2.5 p.ct. HCl, is shown by the following estimations of furfural:

Wood Gum.—The paper contains some observations on the various methods of isolating this product. Attention is directed to the necessary impurity of the product, and to the fact that the numbers for furfural and for the xylose yielded by hydrolysis are considerably less than for a pure pentosane.

Estimation of Cellulose.—The author investigated the process of Lange and the 'celluloses' obtained from various raw materials. The products from the woods of birch and maple contained furfural-yielding constituents, represented by yields of 6-8 p.ct. furfural. Preference is given to the process by comparison with others, at the same time that it is recommended in all cases to examine the product for furfural quantitatively, converting the numbers into pentosane equivalents, and subtracting from the total 'cellulose' to give the true cellulose.

ZUR KENNTNISS DER MUTTERSUBSTANZEN DES HOLZGUMMI.

E. Winterstein (Ztschr. Physiol. Chem., 1892, 381).

ON THE MOTHER SUBSTANCES OF WOOD-GUM.

(p. 188) According to the text-books beech-wood may be regarded as the typical raw material for the preparation of the laboratory product known as wood-gum. The author has subjected beech-wood and beech-wood cellulose (Schulze process) to a range of hydrolytic treatments, acid and alkaline, in order to determine the conditions of selective action upon the mother substance of the wood-gum. In the main it appears that this group of furfuroids is equally resistant with the cellulose constituents of the wood; in fact, that the mother substance of wood-gum is a modified cellulose, and exists in the wood in chemical combination with the 'incrusting substances.'

Of the author's experimental results the following may be cited as typical:

UEBER DIE FRAGE NACH DEM URSPRUNG UNGESÄTTIGER VERBINDUNGEN IN DER PFLANZE.

C. F. Cross, E. J. Bevan, and C. Smith (Berl. Ber., 1895, 1940).

ON THE SOURCE OF THE UNSATURATED COMPOUNDS OF THE PLANT.

(p. 179) In distilling for furfural by the usual methods of boiling cellulosic products with condensing acids, the furfural is accompanied by volatile acids, also products of decomposition of the cellulosic complex. A series of distillations was carried out with dilute sulphuric acids of varying concentration from 10-50 H₂SO₄: 90-50 H₂O by weight, using barley straw as a typical cellulosic material. The distillates were collected in successive fractions, and the furfural and volatile acid determined. The results are given in the form of curves. The aggregate yields were as follows:—

With acids up to 20 p.ct. H₂SO₄ both products are formed concurrently and in nearly equal quantity. With the 30 p.ct. acid there is a great increase in the total furfural, and with the 40 p.ct. acid it reaches nearly the maximum obtainable with HCl of 1.06 s.g. (Tollens), in this case 12.4 p.ct. The volatile acid increases, but in less ratio; it is also produced concurrently. With 50 p.ct. H₂SO₄ the conditions are changed. The total furfural is rapidly formed, whereas the volatile acid continues to be formed long after the aldehyde ceases to come over. Moreover, whereas in the previous cases it was mainly acetic acid, it is now mainly formic acid. The method was then extended to a typical series of celluloses, heated with the more concentrated acid (40-50 p.ct. H₂SO₄), with the following results:

The tendency in the hexoses and their polyanhydrides to split off one carbon atom in the oxidised form, throws some light on the furfurane type of condensation, which is represented in the lignocelluloses. We are still without any evidence as to the possible transition of the hexoses to benzenoid compounds. Such transitions would be more easily explained on the assumption that the celluloses are composed in part of polyanhydrides of the ketoses.

SPIRITUS AUS CELLULOSE UND HOLZ.

E. Simonsen (Ztschr. angew. Chem., 1898, 3).

PRODUCTION OF ALCOHOL FROM CELLULOSE AND WOOD.

(pp. 50, 209) This investigation was undertaken with one main object—to determine the optimum conditions of treatment of wood-cellulose and of wood itself for conversion into 'fermentable sugar.' The process of 'inversion' or hydrolysis, by digestion with dilute acid at high temperature, involves the four main factors: pressure (i.e. temperature), concentration of acid, ratio of liquid to cellulose and duration of digestion. Each of these was varied in definite gradations, and the effect measured. The degree of action was measured in terms of 'reducing sugar,' calculated from the results of estimation by Fehling solution, as 'glucose' per cent. of original cellulose (or wood).

(a) Cellulose. [Wood-cellulose obtained by bisulphite process.]—With a proportion of total liquid to cellulose of 27:1, and using sulphuric acid as the hydrolysing agent, the optimum results were obtained with acids of 0.45-0.60 p.ct. (H₂SO₄) and pressures of 6-8 atm. The maximum yield of 'sugar' was 45 p.ct. of the cellulose.

Under the above conditions the maximum of conversion is attained in 2 hours.

Having now regard to the production of a solution of maximum concentration of dissolved solids, the following conditions were asertained to fulfil the requirement, and, in fact, may be regarded as the economic optimum: