<PICT:0793210/IV (b)/1> <PICT:0793210/IV (b)/2> Filamentary material is treated with liquids while the material is in the general form of a series of crunodal loops arranged in a spiral of diameter greater than that of the individual loops and having its axis vertical or at an angle of at most 30 degrees to the vertical, the material being continuously fed to form one end of the spiral, and treated material being continuously withdrawn from the other end in an uncoiled condition. Preferably, successive convolutions of the spiral rest one on another so that the material assumes the form of a hollow pile, usually of more or less cylindrical form. As shown in Fig. 1, a yarn 11 is fed at a constant rate into a funnel 14 together with a treating liquid which is fed into the funnel at a constant rate from a pipe 16 having a valve 17. The yarn and the liquid fall freely from the stem 18 of the funnel into the fluted entrance arm 24 of a jacketed U-tube 26, where the yarn forms a series of crunodal loops of diameter about 0.25 inch in a spiral of about 0.75 inch diameter, the internal diameter of the U-tube being 1.75 inches. The funnel 14 is loosely supported by a plate 19, the stem 18 of the funnel passing through an aperture in the plate and the bottom part of the stem being moved at a rate of 60 r.p.m. in a substantially circular path 0.5 inch in diameter by means of a motor 22 and a slidably mounted eccentric member 23. The bottom of the spiral rests on a number of circumferentially spaced hemispherical projections 29 (Fig. 3) and builds up to form a hollow, generally cylindrical, pile 31. When this has built up to about the level of the surface of the treating liquid, determined by the adjustment of the overflow device 27 attached to the exit arm 28 of the U-tube, the yarn is withdrawn continuously from the exit arm at the same rate as that at which it is fed into the entrance arm. The process may be used for the further acetylation of cellulose acetate filaments (see Group IV (a)) for the desulphurizing, washing and bleaching of freshly coagulated regenerated cellulose yarns from viscose, and in the saponification and subsequent washing of cellulose acetate yarns.ALSO:<PICT:0793210/IV (a)/1> <PICT:0793210/IV (a)/2> Artificial filamentary material is treated with liquids while the material is in the general form of a series of crunodal loops arranged in a spiral of diameter greater than that of the individual loops and having its axis vertical or at an angle of at most 30 degrees to the vertical, the material being continuously fed to form one end of the spiral, and treated material being continuously withdrawn from the other end in an uncoiled condition. Preferably, successive convolutions of the spiral rest one on another so that the material assumes the form of a hollow pile usually of more or less cylindrical form. As shown in Fig. 1, a yarn 11 composed of filaments of cellulose acetate of acetyl value (as acetic acid) 54 per cent is fed at a constant rate into a funnel 14 together with an acetylation mixture of acetic anhydride, acetic acid, sulphuric acid and benzene at 60 DEG C., which is fed into the funnel at a constant rate from a pipe 16 having a valve 17. The yarn and the mixture fall freely from the stem 18 of the funnel into the fluted entrance arm 24 of a jacketed U-tube 26, where the yarn forms a series of crunodal loops of diameter about 0.25 inch in a spiral of about 0.75 inch diameter, the internal diameter of the U-tube being 1.75 inches. The funnel 14 is loosely supported by a plate 19, the stem 18 of the funnel passing through an aperture in the plate and the bottom part of the stem being moved at a rate of 60 r.p.m. in a substantially circular path 0.5 inch in diameter by means of a motor 22 and a slidably mounted eccentric member 23. The bottom of the spiral rests on a number of circumferentially spaced hemispherical projections 29 (Fig. 3) and builds up to form a hollow, generally cylindrical, pile 31. When this has built up to about the level of the surface of the treating liquid, determined by the adjustment of the overflow device 27 attached to the exit arm 28 of the U-tube, the yarn is withdrawn continuously from the exit arm of the U-tube at the same rate as that at which it is fed into the entrance arm. The period of residence of the yarn in the U-tube is 3 minutes and the yarn leaving the exit arm has an acetyl value of over 61 per cent and may be washed in a similar apparatus. The process may also be used for the desulphurizing, washing and bleaching of freshly coagulated regenerated cellulose yarns from viscose, and in the saponification and subsequent washing of cellulose acetate yarns.