276 Cellulose 



being also high (4o/. to 6o/. per ton), such treatments are not 

 precluded on economic grounds. Moreover, as the natural 

 conditions most favourable for retting are not to be counted 

 on in the capricious climates of temperate regions where the 

 flax is chiefly grown, an artificial process admitting of exact 

 control is very much to be desired. 



The difficulties to be overcome are not so much those of 

 separating the fibre as of separating it in a condition as favour- 

 able for spinning as the product of the natural process or pro- 

 cesses. 



The analysis of the fibre shows that, in addition to the 

 pectocellulose or fibre proper, there is present an unusual 

 proportion of oil- wax constituents (3-4 p.ct.). It appears 

 from later investigations of the spinning process (infra) that 

 the * natural' balance of these constituents constitutes the 

 ' optimum ' of spinning properties. All the artificial processes, 

 which are usually treatments with hot alkaline solutions, disturb 

 this balance, removing both pectic and oily constituents. 

 Moreover, the oils found in the ' natural ' product are in part 

 produced in and by the retting process ; and the pectic con- 

 stituents of the fibre are present, not only in different propor- 

 tion, but in different condition chemically. As a matter of 

 history, these processes have failed technically i.e. in producing 

 a fibre with the high spinning qualities of the ordinary product 

 and with commercial results more or less disastrous. Had 

 investigators based their labours upon the natural model, as 

 defined by exact chemical investigation, such failures would 

 have been obviated. 



But investigation is still needed to elucidate (i) the changes 

 produced in the oil-wax components during retting ; (2) the 

 effect of the retting process upon the pectic constituents of the 

 fibre proper. Upon the results of such investigation it might 

 be possible to devise an artificial process giving similar results, 



