Compound Celluloses 97 



the fibre-substance, at ordinary temperatures, with nitric 

 acid of i*io sp.gr., containing potassium chlorate (o*5-o*8 p.ct. 

 of the weight of the fibre) previously dissolved in the acid. 

 The lignone is attacked jointly by nitrogen and chlorine oxides, 

 and largely converted into derivatives, soluble in the acid 

 solution. The /3-cellulose is also considerably attacked 

 (oxidised), and the action extends to the more resistant (a) 

 cellulose. The residues of the lignone are dissolved away by 

 boiling the washed fibre with dilute ammonia. 



The process has been largely used in investigations of the 

 lignpcelluloses ; but the results, both as to yield and composi- 

 tion of the ' cellulose, are, for obvious reasons, of subordinate 

 value. 



(4) Dilute nitric acid at 50-80. By digesting the fibre- 

 substance with nitric acid (5-10 p.ct. HNO 3 ) at 60, the lignone 

 is entirely converted into soluble derivatives ; the /3-cellulose 

 is also hydrolysed and dissolved ; the residue of the treatment 

 being the more resistant ci-cellulose. The interaction of the 

 lignone and the acid is of use in elucidating the constitution of 

 the non-cellulose groups, and will be subsequently described 

 from this point of view. As a process of cellulose isolation, the 

 reaction is carried out as follows : 



The weighed fibre is placed in a flask and covered with 

 three times its weight of 10 p.ct. HNO 3 . It is heated for 

 some hours at 60 until the fibre has changed to a pale lemon 

 yellow colour, the solution being of a bright yellow. After 

 washing away the acid by-products the residual cellulose is 

 boiled with a solution of sodium sulphite, which removes 

 the last traces of lignone derivatives. It may then be finally 

 washed on a cloth filter, squeezed, dried and weighed. The 

 yields of cellulose by this method are 63-65 p.ct. of the fibre. 



(5) Sulphite and bisulphite processes. By digestion with 

 solutions of the sulphites of the alkalis, or of the bisulphites 



H 



