218 Cellulose 



Thus the wood is an ordinary lignocellulose, and gives the 

 characteristic reactions ; the cortical tissue is again distinguished 

 from the fibre proper by reacting strongly with magenta- sul- 

 phurous acid. The presence of the cortical tissue is also 

 marked by the large proportion of 4 oil and wax ' constituents 

 present in the fibre (3-4 p.ct). Excluding these adventitious 

 constituents the fibre proper is a pectocellulose. That the non- 

 cellulose constituents of flax are pectic compounds was first 

 established by Kolb (Bull. Soc. Ind. Mulhouse, June 1868). 

 According to his observations, the precipitate obtained on 

 acidifying the alkaline solutions from the 'boiling' of flax 

 goods consists of pectic acid. 



The proportion of these constituents varies from 14-33 

 p.ct. in the different kinds of flax, the variations being in part 

 due to the plant, i.e. to physiological habit and conditions of 

 growth ; in part to the different methods of retting the plant 

 and extracting the fibre. After well boiling with the dilute 

 alkali (1-2 p.ct. NaOH) the fibre-substance consists of flax 

 cellulose, with residues of the wood (sprit), cuticular tissues, 

 and oils and waxes associated with the latter. By exposure 

 to chlorine (after well washing and squeezing) the wood is 

 attacked in the usual way, and is then easily resolved by 

 alkaline treatment. To purify the cellulose it requires to be 

 boiled out with alcohol, and finally treated with ether-alcohol 

 to remove the oil-wax residues. In this way flax cellulose is 

 isolated in the laboratory in an approximately pure condition. 

 It might appear from the outlines of this laboratory method 

 that the bleaching of flax goods, which consists substantially 

 in the isolation of the pure flax cellulose, is a comparatively 

 simple process. This is not so, however. The exigencies of 

 economical and safe treatment of textile fabrics prescribe 

 certain narrow limits of chemical treatment ; and the removal 

 of the more resistant wood (lignocellulose) and cuticle 



