CELLU1,OSE I N WOOD
1119
fere with alcoholic fermentation. I n other words the manufacture of a vinegar of standard strength may be seriously affected by a n admixture of acetified apple juice with juice of sound apples. THE ESTIMATION OF CELLULOSE I N WOOD BY THE CHLORINATION METHOD. BY A .I D E A XASD G
E TOWER
T h e chemical constitution of woody tissues presents a problem of great complexity. Any single sample of uood contains a number of complex compounds whose nature is but little understood. If all kinds of wood were chemically alike, or even if the wood from all parts of the same tree was identical, the study of woody tissue would be simplified. T h e older idea, especially the idea prevalent amongst botanists, was that the cell walls of woody tissues were composed of “cellulose” which became impregnated with “lignin.” Later and more careful studies appear to have established the fact that the foundation of woody cell walls is not a simple cellulose, but a compound cellulose, t o which the name lignocellulose, has been given. This lignocellulose may be split up into cellulose on the one hand, and the lignone group on the other. T h e cellulose which results from the cleavage differs to a marked extent from the normal type cellulose of the cotton fiber. The lignone complex appears to contain cyclical groups and to be related to the carboh!drates in no very definite fashion. Besides the lignocellulose Ivhich makes up the major portion of wood, there are alwvl! s present a number of different bodies which are apparently not chcmicallq united to the lignocellulose. Amongst these substances two are prominent; the so-called wood gum, which may be extracted with cold dilute alkaline solutions, and the group of the ether soluble resins. I t was stated above that the lignocellulose might be split into the two constituent radicals, cellulose and lignone. This cleavage is not easily carried out quantitatively, inasmuch as the treatments which remove the lignone tend to attack the cellulose. T h e isolation of cellulose from wood is carried out on an enormous scale in the manufacture of paper pulp by the sulphite and soda processes. These methods are said to always involve some loss of cellulose, and unless carefully regulated the loss is likely to be great. A number of methods have been elaborated for the estimation of the quantities of cellulose in vegetable cell walls. They are all tedious, and the cellulose obtained by several of them is apparently a variable and ill defined product. Cross and Bevanl have elaborated a method for the estimation of cellulose in the lignocellulose of jute fiber, a method which 1 Cellulose: a n Outline of the Chemistry of the Structural Elements of Plants. Cross and Bevan, London, 1895.
A . I,. DEAN A N D G. E. T O W E R
I I20
appears to !.ieltl concortlant and valuable results. I n their inethotl the ligiiocellulose is treatetl ivith chlorine gas. giving rise to a lignoiie chloride which is soluble in hot alkaline sulphite solutions. The!- (lo iiot give t h c restilts o f the systematic application of this methoti to cellulose estiiiiations in \vootl. although they iiiipl!. that it is applicable to such tissues. Shermari', in his sttidy of the insoluble carhoIi!-tlratc.s of the \\heat, estimated the amount of cellulose in the Iignocellulost~of the \\heat kernc.1. After trying out the iiicthotls of Scliulzc. i potassium chlorate antl nitric acitl, i Lange ( fusion ivith caustic alkalies 1 anti the chlorination 1iietho:l of Cross and Ucvan. Sherman concludes that this last iiiethotl gives the ct estimate of the cellulose antl yields cellulose of iiiaxiiiiiiiii purity . Cross and Lievan give the follo\ving directions.' , ' A b o u t j grriis. of the fibre weighed after tlr!,ing at Iooc--L?re ( ( 7 1 boiled for 30 minutcs ivitli a dilute solution of sotliuiii hytlrate ( I per cent. S a O H ) ivliicli is kept at constant ~ o l u m el ~ yaddition of ivater. 1he fiher is \vel1 ivashetl o n a cloth or ivire gauze filter, squeezed to rcmorc excess of \vater. opeii:(l out. placed in a beaker,' into ivliicli ( 0 j ;Lslo\v stream of \vaslietl cliloriiie gas is 1)assetl. Rapid reacticn ensues. aiitl the fiber changes in color, fr(.xii liroivii to a bright golt1e.n !-elloiv. To eiisure coinplete co1iversici:i of the ligiione, it is necessary to leave the fiber for some tiiiie ( from ~ O - < , , O minutes) i n the atmosphere of C1 gas. ( j The clilorinatetl fiber is removed. ivaslietl once or ttvice tvitli v a t e r to remove h!drochloric acitl, ant1 placet1 in a -7 per cent. solution ( ~sotlimii i sull)hitcx : thc solutioii is gradually raised to the hoiling point. a small quaiitit!. of caiistic sotla soltitioil IS atltletl ( 0.2 per cent. S a ( )H calculatetl (.)ii tlic solution i , aiitl thc hoiling coiitinuecl for j minutes. ( d ) The cellulose is no\v thro\vii upoii a cloth filter ant1 \vashetl \\.it11 hot \rater. It \vi11 lie i o ~ i i i t lto be almost pure i.r. white : but to remove the last residues oi tlic lion-cellulose, it may be bleached by immersion i n a tlilute solution h!. li!.pochloritc ( o. I per cent. SaOC1 for a fclv iiiinutes. or treated \\.it11 dilute periiia1igan:itc solution (0.1 per cent. 1
