Page:Encyclopædia Britannica, Ninth Edition, v. 9.djvu/307

 FLAX 295 till they are quite full ; over the top of the upper layer is placed a stratum of rushes and straw, or sods with the grassy side downwards, and above all stones of sufficient weight to keep the flax submerged. Under favourable circum stances a process of fermentation should immediately bo set up, which s;&amp;gt;on makes itself manifest by the evolution of gaseous bubbles. After a few days the fermentation subsides ; and generally in from ten days to two weeks, the process ought to be complete; but everything depends upon the weather ; and as the steeping is a critical opera tion, it is essential that the stalks be frequently examined and tested as the process nears completion. When it is found that the fibre separates readily from the woody &quot; shive &quot; or core, the beets or small bundles are ready for removing from the dams. It is next spread, evenly and equally, over a grassy meadow, where it is left for about a fortnight, at the end of which time the fibres will have partly separated from the core and &quot; bowed.&quot; At this point advantage is taken of fine dry weather to gather up the flax, which is now ready for scutching, but the fibre is improved by stooking and stacking it for some time before it is taken to the scutching mill. Dew-retting is the process by which all the Archangel flax and a large portion of that sent out from St Petersburg arc prepared. By this method the operation of steeping is entirely dispensed with, and the flax is, immediately after pulling, spread on the grass where it is under the influence of air, sun-light, night-dews, and rain. The process is tedious, the resulting fibre is brown in colour, and it is said to be peculiarly liable to undergo heating (probably owing to the soft heavy quality of the flax) if exposed to moisture and kept close packed with little access of air. Archangel flux is, however, peculiarly soft and silky in structure, although in all probability water-retting would result in a fibre as good or even better in quality. The theory of retting, according to the investigations of J. Kolb, is that a peculiar fermentation is set up under the influence of heat and moisture, resulting in a change of the intercellular substance pectose or an analogue of that body into pectin and pectic acid. The former, being soluble, is left in the water ; but the latter, an insoluble body, is in part attached to the fibres, from, which it is only separated by changing into soluble metapectic acid under the action of hot alkaline ley in the subsequent process of bleaching. To a large extent retting continues to be conducted in the primitive fashions above described, although numerous and persistent attempts have been made to improve upon it, or to avoid the process altogether. The uniform result of all experiments has only been to demonstrate the scien tific soundness of the ordinary process of water-retting, and all the proposed improvements of recent times seek to obviate the tediousness, difficulties, and uncertainties of the process as carried on in the open air. In the early part of the present century much attention was bestowed, especially in Ireland, on a process invented by Mr James Lee. He proposed to separate the fibre by v purely mechanical means without any retting whatever; but after the Irish Linen Board had expended many thousands of pounds and much time in making experiments and in erecting his machinery, his entire scheme ended in complete failure. About the year 1851 Chevalier Claussen sought to revive u process of &quot; cottonizing &quot; flax a method of proceeding which had been suggested three-quarters of a century earlier. Claussen s process consisted in steeping flax fibre or tow for twenty-four hours in a weak solution of caustic soda, next boiling it for about two hours in a similar solution, and then saturating it in a solution contain ing 5 per cent, of carbonate of soda, after which it was immersed in a vat containing water acidulated with a half per cent, of sulphuric acid. The action of the acid on the carbonate of soda with which the fibre was impregnated caused the fibre to split up into a fine cotton-like mass, which it was intended to manufacture in the same manner as cotton. A process to turn good flax into bad cotton had however, on the face of it, not much to recommend it to public acceptance ; and Claussen s process therefore remains only as an interesting and suggestive experiment. The only modification of water-retting which has hitherto endured the test of prolonged experiment, and taken a firm position as a distinct improvement, is the warm-water retting patented in England in 1846 by an American, llobert B. Schenck. For open pools and dams Schenek substitutes large wooden vats under cover, into which the flax is tightly packed in an upright position. The water admitted into the tanks is raised to and maintained at a temperature of from 75 to 95 Fahr. during the whole time the flax is in steep. In a short time a brisk fermentation is set up, gases at first of pleasant odour, but subsequently becoming very repulsive, being evolved, and producing a frothy scum over the surface of the water. The whole process occupies only from 50 to 60 hours. A still further improvement, due to Mr Pownall, comes into opera tion at this point, which consists of immediately passing the stalks as they are taken out of the vats between heavy rollers over which a stream of pure water is kept flowing. By this means, not only is all the slimy glutinous adherent matter thoroughly separated, but the subsequent processes of breaking and scutching arc much facilitated. A process of retting by steam was introduced by W. AVatt of Glasgow in 1852, and su-bsequently modified and improved by J. Buchanan. The system possessed the advantages of rapidity, being completed in about 10 hours, and freedom from any noxious odour ; but it yielded only a harsh, ill-spinning fibre, and consequently failed to meet the sanguine expectations of its promoters. In connexion with improvements in retting, Mr Michael Andrews, the energetic secretary of the Belfast Flax Supply Association, has made some suggestions and experiments which deserve close attention. In a paper contributed to the International Flax Congress at Vienna in 1873, he entered into details regarding an experimental rettery he had formed, with the view of imitating by artificial means the best results obtained by the ordinary methods. In brief, Mr Andrews s method consists in introducing water at the proper temperature into the retting vat, and main taining that temperature by keeping the air of the chamber at a proper degree of heat. By this means the flax is kept at a uniform temperature with great certainty, since even should the heat of the air vary considerably through neglect, the water in the vat only by slow degrees follows such fluctuations. &quot;It may be remarked,&quot; says Mr Andrews, &quot; that the superiority claimed for this method of retting flax over what is known as the hot-water steeping is uniformity of temperature ; in fact the experiments have demonstrated that an absolute control can be exercised over the means adopted to produce the artificial climate in which the vats containing the flax are situated.&quot; Scutching is the process by which the fibre is freed from its woody core and rendered fit for the market. For ordinary water-retted flax two operations are required, first breaking and then scutching, and these are done either by hand labour or by means of small scutching or lint mills, driven either by water or steam power. Hand labour, aided by simple implements, is still much used in Continental countries ; but the use of scutching mills is now very general, these being more economical, and turning out flax of a much better quality. The breaking is done by passing the stalks between grooved rollers, to which in some cases a reciprocating motion is communi-