114 Cellulose 



In an atmosphere saturated at ordinary temperatures jute takes 

 up 23 p.ct. of moisture. 



The hydration of the fibre-substance, in the more permanent 

 sense of definite combination with H 2 O molecules, is determined 

 under conditions which will appear in the succeeding sections 

 of the subject. 



Solutions of Lignocellulose. The jute fibre is attacked 

 and dissolved by the solvents already described under * Cellulose ' 

 (p. 8), viz. : 



(1) Zinc chloride concentrated aqueous solution. 



(2) Zinc chloride solution in HC1 ; and 



(3) Cuprammoniun solutions. 



From these solutions the lignocellulose is precipitated, on 

 dilution (i and 2) or acidification, as a gelatinous hydrate ; the 

 precipitation is, however, incomplete the proportion remaining 

 in solution varying from 15-25 p.ct., according to the condi- 

 tions of solution. There is, however, no difference in reactions 

 between the soluble and insoluble fractions, and on ultimate 

 analysis both are found to have the empirical composition of 

 the original fibre-substance. Although, therefore, the ligno- 

 cellulose is a complex of various groupings, it behaves in this 

 respect as a homogeneous product, and the bond uniting the 

 groups together is not resolved by simple hydrolytic agencies 

 (see infra, p. 134). 



In the case of the ZnCl 2 .HCl reagent the fibre-substance is 

 progressively hydrolysed on standing. This is illustrated by the 

 following determinations of the proportion of the lignocellulose 

 reprecipitated from such solution. 



(a) Precipitated at once : ppt. 78-4 p.ct. of the original. 



() After standing 16 hours : ppt. 29-4 p.ct. of the original. 



Qualitative Reactions and Identification of the 

 Lignocelluloses. Whereas the reactions of the celluloses 

 are mostly negative, jute (and the lignocelluloses generally) is 



