98 Cellulose 



of the alkaline earths, at high temperatures, the lignone groups 

 are attacked and dissolved, as the result of a specific reaction, 

 which will be subsequently dealt with in its bearings upon 

 the constitution of the lignone molecule. 



As a ' cellulose process,' the reaction may be carried out as 

 follows : 



Neutral sulphite. The fibre is sealed up with five times its 

 weight of a 6 p.ct. solution of sodium sulphite (Na 2 SO 3 .7H 2 O). 



Bisulphite of lime or magnesia. The fibre is sealed up 

 with five times its weight of the bisulphite solution containing 

 3 p.ct. total SO 2 . 



The digestion is carried out at high temperatures either in 

 glass tubes or autoclaves of metal, according to the circum- 

 stances of the laboratory. In the latter case, iron vessels may 

 be used with the neutral sulphite, but to prevent reaction with 

 the metal, the solution should contain sodium carbonate ( the 

 weight of the sulphite). For the bisulphite treatment a lead- 

 lined digester is required. The maximum temperatures 

 necessary are 180 for the neutral sulphite, 160 for the bi- 

 sulphite process. 



The temperature is raised gradually to the maximum, at 

 which it is maintained for 2-3 hours, the entire duration 

 of digestion necessary being from 6-8 hours. At the expira- 

 tion of this time, the vessels are cooled off, the contents 

 thrown on to a cloth filter, the residual cellulose washed 

 thoroughly with hot water, and finally purified by treatment 

 with dilute hypochlorite (0-5 p.ct. NaOCl) or permanganate 

 solution. After washing from the oxidising solution, the cellu- 

 lose is treated with sulphurous acid, from which it is thoroughly 

 washed, squeezed, and dried for weighing. 



The yields of cellulose are from 60-65 P* c ^ > tne /3-cellu- 

 Icse being, under this treatment, also hydrolysed and dis- 

 solved. 



