Researches on Cellulose Part 18

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 a.s.sam.

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 ill.u.s.tration we may cite (a) the results of a.n.a.lyses 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.

__________________________________________________________________ Quality of Jute ____________________________ _____________________________________ Low Medium Extra Extra Fine ____________________________ _______ ________ _______ ____________ Moisture 11.0 10.4 11.1 9.6 Ash 0.87 2.8 1.0 0.7 Alkaline hydrolysis (a) 5 mins. boiling 13.2 11.6 8.5 9.1 Alkaline hydrolysis (b) 60 mins. boiling 16.1 17.5 12.5 13.1 Mercerising treatment 9.2 10.5 10.3 8.5 Nitration (increase p.ct.) 36.6 35.7 37.5 36.7 Cellulose (yield) 71.4 70.0 79.0 77.7 Acid purification 2.6 1.3 1.9 2.0 ____________________________ _______ ________ _______ ____________

A useful series of experiments, initiated by the Inst.i.tute, 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, quant.i.ties of 400 lbs. of the stalks were cut at successive stages and the fibre isolated after steeping 14-20 days. The fibre was s.h.i.+pped to England and chemically investigated, with the following results:

No. 1. Cut before appearance of inflorescence.

" 2. " after budding.

" 3. " in flower.

" 4. " after appearance of seed-pod.

" 5. " when fully matured.

_________________________________________________________________ (1) (2) (3) (4) (5) ___________________________ _______ _______ ______ ______ _______ Moisture 11.55 8.74 10.7 10.0 9.72 Ash 1.1 1.1 1.1 1.1 0.90 Alkaline hydrolysis (a) 6.2 8.5 9.7 8.9 7.3 " " (b) 10.5 11.9 11.6 12.0 11.2 Mercerising treatment 10.2 10.7 12.0 8.1 11.0 Nitration 37.2 32.1 32.2 33.2 36.6 Cellulose 74.0 76.2 74.1 74.8 76.4 Acid purification 0.8 0.5 0.7 2.4 1.4 ___________________________ _______ _______ ______ ______ _______

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 a.s.sumed 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 s.h.i.+pment. The samples were s.h.i.+pped 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 s.h.i.+pment.

The other matters investigated in the Inst.i.tute 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:

________________________________ Wood _______________ Bark Inner Outer _________ _______ _______ ______ May 21.3 19.6 16.7 July 16.6 18.8 11.4 October 16.2 16.3 12.3 _________ _______ _______ ______

The paper contains the results of treating the woods and various vegetable products with hydrolysing agents in order of intensity: (a) Malt-extract at 60C., (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:

________________________________________________________________________ Birch Stones of _____________ __________________________ Bark Wood Date Apricot Peach _______________________________ ______ ______ ________ _________ _______ Action of malt extract calcu- lated as starch dissolved 4.24 3.5 5.2 1.5 -- Residue boiled, 1 p.ct. HCl Mannan gave pentosanes dissolved. -- -- 11.7 14.1 6.7 Residue yielded furfural 19.3 17.8 3.4 9.6 9.7 _______________________________ ______ ______ ________ _________ _______

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:

_________________________________________________________________ Birch Sugar maple ______________ _______________ Apricot stones Bark Wood Outer Inner wood wood ________________________ _______ ______ _______ _______ _________ In original substance 16.7 19.6 18.2 20.7 18.4 In residue from action 6.53 8.6 4.9 6.4 7.0 of 2.5 p.ct. HCl ________________________ _______ ______ _______ _______ _________

_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 const.i.tuents, 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 quant.i.tatively, 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 const.i.tuents 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:

Yield of furfural Substance p.ct.

Original beech-wood 13.8

After boiling 3 hrs. with 1.25 p.ct. H_{2}SO_{4} (residue) 10.1

" " " " 5.0 " " " 5.6

Cellulose--isolated by Schulze process (yield 53 p.ct.) 6.9

" after further 14 days' digestion with the Schulze acid (HNO_{3} + KClO_{3}) 5.9

" after extraction with 5 p.ct. NaOH in cold (residue) 5.0

" after second extraction with 5 p.ct. NaOH in cold (residue) 4.4

UEBER DIE FRAGE NACH DEM URSPRUNG UNGESaTTIGER 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 H_{2}SO_{4} : 90-50 H_{2}O 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:--

Concentration of acid (H_{2}SO_{4}) p.ct. 10 15 20 30 40 50

Furfural yield p.ct. of straw 2.0 2.0 4.4 10.1 11.5 11.0

Volatile acid (calculated as acetic acid) p.ct. of straw 1.7 1.9 3.1 4.3 6.3 14.8

With acids up to 20 p.ct. H_{2}SO_{4} both products are formed concurrently and in nearly equal quant.i.ty. 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. H_{2}SO_{4} 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. H_{2}SO_{4}), with the following results:

__________________________________________________ Volatile acid _________________ Acetic Formic ________________________ _______ ________ ________ Swedish filter-paper 0.3 2.7 17.2 Esparto cellulose 12.4 3.2 16.6 Bleached cotton trace 3.1 13.2 Raw cotton (American) -- 5.0 9.4 Jute cellulose 5.2 4.9 22.7 Beech (wood) cellulose 6.4 3.5 14.6 ________________________ _______ ________ ________