• The "(lumping machine " ia rather a speciality in yarn and thread bleaching, where the chain form is used. It conbists of a pair of heavy wooden rollers set over a large water trough. The upper roller is covered with close coils of cotton rope, to render it somewhat elastic. This roller rests with ite own weight on the lower one, so that the knots or lumps produced by the plaiting or linking of the chain causo it in passing through to rise and fall with a jumping motion, thus squeezing the soap solution and blue into the very heart of the fibre. This part of the process adds very considerably to the beauty of the white. When the yarn or thread is handled in hank form, this treatment with soap solution takes place in the wash stocks, Fig. 372 ; A is the box or trough, made of a aolid piece of wood, containing the yarn ot thread at F, and fed with water from the pipe H ; B and C are two heavy wooden hammers, working side by side into the same trough. They are supported by a strong loose iron bolt at D, and are raised alternately and allowed to fall again by the cams on the revolviog shaft E. G is a table to hold yarn ready for entering the machine.
A special washing machine also is required when the yarn is in hank form. Fig. 373 gives a representation of the ingenious machine devised by Gantert. It consista of an annular or oval shaped fr.:nigh A of any auitable size, in combination with a series of radial horizontal revolving arms working above the t-rough. A roller B is carried on the outer end of each arm which serves as its az* and the several rollers revolve immediately over the trough. The hanks or skeins C to be washed are hung upon the rollers as indicated, and their lower ends dip into the water in the trough, in which a partitiorr is fitted. The water enters on one side of Ulla partition, where the banks are taken off, circulates round the trough, and escapes on the other side of it, where the hank(' are entered. By a complicated mechanism, the hanks are moved along, at the same time that the rollers B revolve, and cause them to vary their position in the water ; in addition to this, the arms, rollers, and hanks have a backward and forward movement. The machine may be made of such dimensions that one circulation will give a sufficient wash ; the hanks for washing are constantly put on to the rollers B by a workman on one side of the water-trough division, and are as rapidly taken off thoroughly washed by another workman on the other side of the division. The whole action imitates, in a striking manner, the washing of a Mink as it is done by hand.
Woollen Bleaching.—As already mentioned, the bleaching of wool differs entirely from that of cotton, since their chemical and physical properties are dissimilar. Strong alkalies dissolve it, and bleaching-powder solution decomposes and destroys it, with evolution of nitrogen gas.
In general terms, tbe bleaching of wool consists " scorning," or washing with water, solutions of soap, and weak alkalies ; and in bkaching or whitening, by means of sulphurous acid. The use of sulphurous acid, and of ammoniacal liquors in the form of " lant '' or stale urine, is known (from drawings on the walls of Pompeii) to have been practised by the Romans.
Wool Washing.—The preliminary step in woollen bleaching consists in removing, by washing, a portion of the glint and other adhering impurities. This may take place before shearing, in vvhich case the animals are led into a running stream of suitable depth. Three to five men enter the brook, and the animals are washed by each successively, finishing with the man standing in the upper part of the stream. The loss in this operation may vary from 20 to 70 per cent. This first washing may also take place after shearing, in which case, the fleece is steeped in cold water, and is then washed in wicker baskets or nets in a running stream, or in large tubs. Fine wools are afterwards washed in warm water, drained, and spread on the grass or in stoves to dry. The drying machines recently introduced by Petrie and Fielden, of Rochdale, may be used with advantage.
Wool Scouring.—When the manufacturer or dyer receives the wool, it is further washed or " scoured" with the following detergents : for fine long wools, soft soap ; for short wools, coarse or fine, stale urine, alone or mixed with soda ash, also soda ash alone, silicate of soda, and mixtures of alkaline carbonates and soap. When stale urine is used, the loose wool is plunged into a large tub, containing about 1 measure of stale urine to three or four measures of water ; after being worked about with a stick or stang for five or ten minutes, it is lifted out with a fork on to a drainer or seray. When sufficiently drained, the wool is thrown into a cistern provided with a perforated false bottom ; here it is well washed and worked about in cold water two or three times, the water being let off below between the washings. This method requires, of oourse, an abundant supply of water ; by it, one man can scour from 500 lb. to 600 lb. per day. An improvement upon this rnethod, used in some places, is to have a perforated sheet-iron box swung on a crane. The per forated box is let down into the scouring tub, and the wool is worked about in it ; it is then raised, and allowed to drain, after which the wool is tilted into the washing cistern, to be washed two or three times as before. This arrangement requires two men ; but more work eau be got through. Long-stapled wools are worked about with forks in the scouring liquor. When soap is used, the wool is passed between squeezing rollers, before washing off in water. An excellent scour is also obtained by using resin soap made with soda ash (see Cotton Bleaching).