Though the above methods are in general use in small works, they aro superseded in large establishments by tho wool-scouring machines. Fig. 374 shows a " single four-rako " machine, made by Messrs. J. and W. MeNaught, Rochdale. It consists of a large cast-iron trough, fitted up with an ingenious arrangement of forks or rakes. The loose wool is introduced by a boy at one end of the trough ; by the movement of the rakes, it is well worked about in the scouring liquor and carried gradually forward to the other end of the trough, there to be lifted out of the liquor by a special mechanism, passed through a pair of squeezing rollers and thrown off, by a fanner, in a semi-dry condition. The wool is then brought back from the delivery to the entering end, and is passed through twice or thrice, using either fresh scouring liquor or water, as required. With a complete machine of three troughs, ranged in a line, the wool is passed by self-acting machinery from one trough to another, and is finished at one operation. If the scouring-honse be small, one of the troughs may be made angular, to fit into the corner.
The wool to be scoured is placed upon the apron or feeder a, which carries it to the trough ; it is then pressed into the liquor by the rotating immerser b, and passed forward by the reciprocating rakes c c ; e is a stationary rake, which the reciprocating rake intersects ; its use is to prevent the wool from passing forward too quickly. The stationary rakes are hung on pivots, and are adjustable to -any angle, to suit the various qualities of wool. After baying been carried forward by the washing rakes, the wool is lifted out by a swing rake at the other end of the trough, and is carried on to the second trough, by a very ingenious contrivance, represented in section on a larger scale in Fig. 375. A is the swing rako with a double row of prongs, which work close to the end of the trough, being of the same curve as that traced by the point of the prongs. The wool is, by this means, lifted out of the liquor, and deposited at the bottom of the inclined plane. In order to prevent the wool from being washed back into the trough by the surge of the liquor, a number of retaining prongs c, at the bottom of the incline, shoot up from beneath the incline directly the wool is landed on it. H is a flat rake or frame, with short prongs projecting below (similar to a harrow as used for agricultural purposes); this rake is worked by the cams I upon which it rests, and by the crank K, and is so actuated that, after the wool has been deposited at the bottom of the incline, it drops upon it and drags it up the incline, to the extent of its stroke (about 13 in.); it then rises, and returns over the wool, to drop upon it and drag it up again, the retaining prongs withdrawing immediately that the rake drops upon the wool. The rake H works stroke for stroke
with the lifting rake A, and drags up the incline all the wool which is deposited at the bottom. The wool, being pushed by the rake over the end of the incline, emerges upon a series of metal rollers M, about 3 in. in diameter, all revolving in one direction, wlaich carry it forward to the squeezers. These rollers M are so driven that each succeeding roller shall revolve quicker than the one before it ; this continual increase of speed effectually prevents any wool from getting down between the rollers, distributing it evenly, and enabling it to enter the squeezers in a continuous sliver, without losing even the shortest fibres. The squeezing part N is strong, and is fitted with escapement motion, to ensure equal surface speed in the two rollers. P is the inlet of the liquor expressed by the squeezers, and conveyed back to the trough by a pipe. After passing the squeezing rollers, the wool is cleared from them by the roller Q revolving in the same direction, with a slightly increased surface speed. The wool falls from this " clearer roller " directly into the second trough, to be carried forward by the washing rake as before. At the end of the third trough, a delivery fan, about 2 ft. in diameter, is placed behind the squeezing rollers, and, after passing between them, throws off the wool in a semi-dry condition. Each trough is fitted with a perforated false bottom, with space underneath to allow the dirt and mud to settle ; Z is a water-pipe for swilling the mud away. The bottom of the trough slopes downwards from the delivery to the feed end, and a large outlet valve is placed at the lowest point. Between and beneath each two troughs, is placed an injector S ; a jet of steam, introduced into the connecting pipe U, causes the liquor to pass (wieldy from one machine to the other ; by this arrangement, all the troughs may work together on the same level. The first trough contains a strong scouring liquor ; the second, a weaker one ; and the third may contain running water. Besides the one described, there are other good machines by Petrie and Leech, each possessing special features. The loss in this scouring may range from 35 to 45 per cent. The temperature of the scouring liquor is about 54i° (130° F.). The active principle in stale urine is the carbonate of ammonia, produced by fermenta tion ; this forms an emulsion with the fatty matters. When carbonate of soda is used, the strength of the solution should be about I lb. to lb. soda, per 10 galls. water. For fine wool, soap and soda is sometimes used. It is seldom that loose wool is sulphured.