120 Cellulose 



decomposed with formation of furfural and acetic acid ; when 

 formed at temperatures below 70, it may be regarded as a 

 soluble hydrate of the lignocellulose, or more correctly a 

 derivative of low molecular weight in which the characteristic 

 groupings of the parent molecule are preserved. 



Concentrated solutions of the alkaline hydrates. The struc- 

 tural changes produced in the fibre by treatment with solu- 

 tions of caustic soda of 'mercerising' strength (15-30 p.ct. 

 NaOH) are remarkable. The fibre-bundles are resolved more 

 or less ; the cell wall of the individual fibres undergoes con- 

 siderable thickening, such that the central canal is almost 

 obliterated. The visible effects of these changes of minute 

 structure are (i) a shrinkage in length of the strands of fibre 

 (15-20 p.ct.) ; (2) a considerable refinement of the spinning 

 units or filaments ; (3) the filaments have a wavy or crinkled 

 outline, resembling that of wool. 



The following experimental results may be cited : 80*35 grms. 

 fibre (air-dry) treated with 300 c.c. of 25 p.ct. solution NaOH, 

 six hours in the cold ; washed, acidified, washed and dried ; 

 weighed, air-dry, 75-5 grms. Loss of weight, 6 p.ct. Shrinkage in 

 length, from 4 ft. to 3 ft. 8 in., i.e. 17 p.ct. 



An extended series of experiments upon normal specimens of 

 the raw fibre, with varied conditions e.g. concentration of alkali, 

 15-33 p.ct. NaOH ; duration of treatment, 5 minutes to 48 hours 

 showed an average loss of weight of 7-5 p.ct., with slight vari- 

 ations only on either side of this mean number. The same speci- 

 men of jute lost 1 1 -9 p.ct. in weight on digesting 48 hours in more 

 dilute alkali (6-5 p.ct. NaOH), and n p.ct. on boiling for 5 

 minutes in alkali of the same concentration. 



The cellulose constants of the fibre are unaffected by the treat- 

 ment. 



The chemical changes are more complex than with the 

 celluloses, for reasons which will appear whefi the constitutional 

 relationships of the constituent groups of the fibre-substance 



