174 Cellulose 



tissue of the woods i.e. the woods freed from adventitious con 

 stituents such as tannins, colouring matters, resins, &c. is 

 composed of substances which cannot be resolved by hydro- 

 lytic treatments into proximate components ; and (2) that there 

 is a striking uniformity in composition of the fundamental tissue 

 of the woods, notwithstanding their structural complexity ; 

 and this uniformity embraces not merely the individuals of a 

 species, but extends over the widest range of such products. 



Mention should be made here of a general property of the woods, 

 and lignocelluloses discovered and investigated by C. Wurster, 

 viz. that of fixing atmospheric oxygen in the form of a peroxide, 

 giving the reactions of the typical hydrogen peroxide. One of 

 these is the oxidation of the methylated derivatives of paraphenyl- 

 endiamine to red colouring matters and this reaction is equally 

 and generally characteristic of the woods. Wurster has, in fact, 

 reduced the reaction to an approximate quantitative estimation of 

 the proportion of ' mechanical wood pulp ' in papers. The reagent 

 in question is incorporated in definite proportion with a pure 

 cellulose paper, which is used as a 'test paper' ; the paper to be 

 tested being moistened with water, and the test paper pressed into 

 the moistened part. The depth of colour is compared with standard 

 coloured papers constituting a scale, the oxidising effects producing 

 the colour being also expressed in terms of normal iodine solution. 

 The percentage of wood in the paper corresponds to the depth of 

 colour produced on the test paper. 



For an account of Wurster's researches, which have been 

 extended to a number of organic products, and are of considerable 

 physiological interest, see Berl. Ber. 1887, 20, 808 (Quantitative 

 Bestimmung des Holzschliffes im Papier), and also pp. 256, 263, 

 1030, 2631, 2934. From these it appears that the reaction, in the 

 case of the woods, is the expression of quinonic constitution of 

 characteristic (hexene) groups. 



EMPIRICAL COMPOSITION (ELEMENTARY ANALYSIS) OF 

 WOODS. The uniform composition of the woods has been for 

 many years regarded as established on the basis of the analyses 

 of Chevandier (Ann. Chim. Phys. [3], 10, 129), which are still 



