8o Cellulose 



It has been already pointed out that these celluloses occur in 

 admixture or combination with other substances, often grouped 

 together in the term non-cellulose ; cellulose and non-cellulose 

 being usually separated jointly from the plant, and constituting 

 the * raw fibre.' The raw fibre is therefore usually a compound 

 cellulose, though in some cases a compound of a very weak order. 

 These points will be best illustrated by a careful study of com- 

 mercial flax. Flax -is made up of the pure fibre, which is a 

 compound cellulose, with a certain admixture of the tissues with 

 which it is in contact in the stem. These adventitious components 

 are largely got rid of, first in the processes of breaking and scutching, 

 and afterwards in the further refining processes of hackling and 

 preparing, by which the spinner brings the fibre into the proper 

 condition for the twisting or spinning process proper. But the 

 yarn still retains residues of the cuticular cells and wood (sprit), 

 which then require to be broken down, or converted into cellulose, 

 by the chemical processes of bleaching. It is the former which 

 occasion the major difficulties of the linen bleacher. As a result of 

 the intimate association of the fibre with the cuticle of the stem, 

 flax, as finished for the market, contains an unusually large propor- 

 tion of oil -wax constituents, i.e. from 3-5 p.ct. of such bodies, soluble 

 in the special solvents. These may be separated by fraction- 

 ation into (a) ceryl alcohol and derivatives (esters), and (b} a mixture 

 of oily bodies of ketonic character. 



For more detailed investigation of this group of flax constituents 

 see Hodges, Proc. R. I. Acad. 3, 460 ; and Cross and Bevan, 

 J. Chem. Soc. 57, 196. 



This oil-wax complex plays an important part in the ordinary 

 process of flax 'line' spinning, and the failure of many of the 

 artificial processes of 'retting' flax may be explained by the 

 deficiency of the resulting fibre in these constituents. In the 

 breaking down of the cuticular celluloses, whether in the retting 

 (rot-steep) or bleaching process, these waxes and oils are separated. 

 Their elimination from the cloth necessitates the very elaborate 

 treatment by which the ' Belfast Linen Bleach ' is obtained. 



These constituents are adventitious impurities, the bast fibre 

 itself being a pectocellulose (see p. 214), easily resolved by alkaline 

 saponification into cellulose on the one hand, and soluble modifica- 

 tion of the pectic group on the other. Although, therefore, the 



