244 Cellulose 



should sow some flax (linseed) and examine the stem at intervals 

 throughout the growth of the crop, noting the development of the 

 bast fibre which constitutes commercial flax and its structural 

 relationship to wood and cortex. 



Mount as permanent preparations the typical paper-making 

 celluloses : cotton, flax, hemp, wood, esparto, and straw. Note 

 dimensions and typical characteristics. Study the photomicro- 

 graphs of raw materials (sections appendix), And an account of 

 methods of photographing, in Indian Fibres, p. 15. 



Bleaching-, or Isolation of Cellulose from Raw Fibres. Take 

 flax and jute as typical raw materials. 



Flax. Extract the fibre in continuous extraction apparatus 

 (Soxhlet) with fat solvents e.g. alcohol ether. Make quanti- 

 tative estimations, and for study of properties of oil-wax extract 

 see Cross and Be van, J. Chem. Soc. 57, 196. 



Boil extracted residue with 2 p.ct. solution NaOH one hour. 

 Examine solution for pectic bodies and note properties. Wash, 

 and bleach fibre in o - 5 p.ct. solution sodium hypochlorite ; wash 

 off, treat with sulphurous acid, wash, dry, and weigh. Note that the 

 fibre though colourless has a blackish look. A second portion boil 

 as before, wash, and digest in bromine water some hours. Wash 

 and boil out in carbonate of soda solution. Wash and return to 

 bromine water. Repeat till brilliant white cellulose obtained. 

 Note the gradual disintegration of the woody portions (* sprit ') 

 which adhere to the fibre. 



Jute fibre. Boil 15 minutes in I p.ct. NaOH solution ; wash oft", 

 squeeze, and expose to chlorine gas one hour. Note formation of 

 yellow chlorinated derivative of non-cellulose. Wash off and 

 place in 2 p.ct. solution sodium sulphite. Raise to boil, adding a 

 little NaOH. Wash off and treat residual cellulose with sulphurous 

 acid. Wash off, dry, and weigh. 



Pine wood. Take deal shavings or 'wood-wool' and proceed 

 as with jute, repeating the treatment with chlorine until pure 

 cellulose obtained. 



Contrast these laboratory methods with those of the bleach 

 works (cotton, linen) and the paper-maker's * pulping ' processes, 

 for which see the standard text-books on these subjects, more 

 especially Chemistry of Paper Making (Griffin & Little : New- 

 York, 1894). 



