PROJECTED REVIVAL OF THE FLAX INDUSTRY 623 



The straw is twice retted and during each operation the water is 

 changed at least twice. At the retting station at Oenkerk in 

 Friesland there are three pairs of retting tanks which are built 

 of stone and lined with wood and these also are fitted with 

 steam-pipes beneath a false bottom. The temperature of the 

 water is maintained at about 30 C. during about three days and 

 nights— until the straw is properly retted— then the water is 

 run off into a field drain and the straw is arranged in " steeples " 

 to dry. 



Near Bruges, there is a larger station than at Oenkerk, 

 where an almost identical plan is adopted ; the retting being 

 completed in seventy-two hours. Double-retting is practised at 

 Appingadam Central Rettery, where the retting tanks are 

 arranged in series or batteries of four. The tanks are made 

 of concrete and are each provided with an inlet at the bottom for 

 warmed water, overflow pipes and exit pipes and above each 

 battery of tanks there is a reservoir fitted with steam circulator 

 pipes where the required quantity of water is warmed prior to 

 entering the retting tanks. 



Early in the nineteenth century retting was studied from the 

 biological side and it was soon established that it was primarily 

 a fermentation process : it was not, however, until much work 

 had been done on this subject that any further definite knowledge 

 was obtained. In 1868 Kolb put forward views regarding the 

 more exact nature of the retting process, namely, that it was 

 a pectin fermentation process whereby the insoluble inter- 

 cellular substance was removed as soluble products of fermenta- 

 tion, thus allowing the fibre to be separated. 



This explanation was warmly contested by Tieghem and 

 others who supported the view that the process involved the 

 resolution of the cell structure and the dissolution of the 

 cellular membrane by a specific anaerobic organism. The 

 investigations of Fribes showed that the flax stems themselves 

 carry a definite anaerobic bacterium of somewhat large size 

 which is active towards the intercellular substance but which is 

 quite inactive towards cellulose ; this view is held at the present 

 day, although it is sometimes suggested that there are naturally 

 on the flax stems several species of bacteria which are concerned 

 in the retting. 



The recent researches of Stormer (1904) and of Hoffmeister 

 (1905) show that the chief retting organism is not difficult 

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