Compound Celluloses 93 



the purpose are chiefly the halogens, the halogenated deriva- 

 tives of the non-cellulose being dissolved away by treatment 

 of the product with alkaline solutions. The cellulose thus iso- 

 lated is not homogeneous, but is made up of a more resistant 

 a- and a less resistant /3-cellulose more or less resistant, 

 i.e. to the action of oxidants and hydrolytic agents. By other 

 reactions, therefore, in which the oxidising or hydrolysing 

 conditions are more severe, the /3-cellulose is converted into 

 soluble derivatives. Such are, digestions with dilute nitric 

 acid ; with permanganates, in presence of alkali in excess ; 

 with solutions of the bisulphites at elevated temperatures. This 

 /3-cellulose is characterised by the presence of O.CH 3 groups. 

 The a-' cellulose ' is an oxycellulose. 



There are other minor characteristics of the non-cellulose 

 portion of the fibre-substance which remain to be noticed. 

 These are (i) the presence of OCH 3 groups, in larger propor- 

 tion than in the /3-cellulose ; (2) the presence of a CH 2 .CO 

 residue, which is split off as acetic acid, under various hydrolytic 

 treatments of the fibre-substance, probably in union therefore, 

 as a side chain, with the R. hexene groups ; (3) the presence of 

 a body giving the characteristic reactions of the pentaglucoses. 

 The pentosans are, in fact, obtainable in small quantity as 

 products of alkaline hydrolysis of the fibre-substance ; and the 

 furfural-yielding constituent of the non-cellulose, already de- 

 scribed as a condensed oxycellulose derivative, might be assumed, 

 on this evidence, to possess the pentose configuration ; but the 

 evidence available so far is not such as to give a definite 

 solution of this point. 



These are the main points of constitutional differentia- 

 tion of the lignocelluloses from the celluloses proper. It has 

 been largely the custom to describe the compound celluloses 

 of this class as mixtures of cellulose' and non-cellulose, the 

 latter being described generally as 'encrusting matters/ or 



