Relationship between “Characteristic form of Filtration” and filtered particles is explained, and the derivation of this relationship is studied in the case of constant rate filtration test. The obtained results are as follows. (log P/P₀)/t=C•K-C/2•K²•t where C=1/n'(1-n) n': structural viscosity coefficient of filtered solution n: index of characteristic form _??_ (_??_=dR/dV=KRⁿ) P: filtration pressure P₀: initial filtration pressure t: filtration time K: filtration constant n indicates the relative size of filtered particles to the hole of filter media, and K indicates the number of particles and the whole filtration obstruction is measured by C•K which includes the effect of both size and number of filtered particles.
The experimental results of constant rate filtration test for viscose are in good agreement with the above equation. Further, the values of n, K, C•K are compared with microscopic observation of undissolved fibers in viscose.

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Acetylations with ZnSO₄ and ZnCl₂ are investigated in some detail. In these cases, acetylation proceeds smoothly even after replacement of water contained in the fibers with other solvent vapors such as benzene, ethylene chloride and carbon tetrachloride. Highly acetylated fibers without serious damage may be thus obtained in a considerably short time. CH₃COONa is also fit as a catalyzer when it is used in higher concentration and acetylation may be carried out at a higher temperature.

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Perchloric acid and hydrochloric acid are used. HClO₄ is more effective than H₂SO₄, but HCl is less effective. Difference of catalytic action of these acids may be due to difference of hydrogenion strength of these acids in the acetylation medium

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Some properties of the acetate rayon which was prepared through acetylation of viscose rayon with acetic anhydride vapor were measured. Polymerization degree falls from 300 of the raw viscose rayon to 200-150. Although under suitable conditions acetylated fibers with higher tensile strength than the original viscose fibers may be obtained, a fall of tenacity (g/den) is inevitable as the denier of fibers increases with acetylation. Highly acetylated fibers can be dyed uniformly by celliton dyestnff etc.. Dyed viscose fibers may also be acetylated smoothly.

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Sixteen kinds of burnishing paints were made from gum arabic, gelatin, milk casein, P. V. A, C. M. C and their mixtures. Results from the abrasion tests with a cotton band on the roller surface or with a file attached to it, differ widely from the durability measured on the practical operation tests.
From the operation tests on the ring spinning frame, milk casein, P. V. A and their mixtures which have large cohesion force and high resistance to scrapping have shown superior durability, and their compositions are as follows.
milk casein 8%+C. M. C 1%, milk casein 5%+P. V. A. 5%, P. V. A 4%+ C. M. C 1%, and P. V. A 5%+gum arabic 3.25%+gelatin 1.75%.

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It is found that the relation between the surface friction f of cotton fabrics and the normal pressure R is generally well expressed by the following equation, when R is under 40g/cm².
f=aRⁿ where a and n are constants for the given surface of a fabric.
So it is difficult to explain fully the relation between f and R only with μ, the coefficient of friction.
Therefore the degree of slippage S is adopted.
when n=1, μ=1/S
For cotton fabrics, a>1, 1>n>0
The more the yarn is twisted and the denser the fabric is in the direction of slip, the larger S becomes.

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The Tootal-Broadhurst-Lee Company's method was improved as follows: A cloth is conditioned for 2 days at 25°C and 65% R. H., from which the test pieces of 2cm long and 1cm wide are cut by means of a cutter. A test piece is folded across the narrow dimension and placed between two glass plates and loaded with a 500gm weight for 1hour. It is then allowed to recover for 10min. while hung over a horizontal wire of 0.3mm diameter, and then the distance l between the ends is read with a calipers. During the test the air is conditioned at 25±0.5°C and 65±1% R. H.
The long dimension of the test piece was shortened to 2cm, in order to obtain the value of l, l=2sinθ/2 where θ is the crease angle.
The process of crease recovery was followed in order to estimate the value l at equilibrium from an exact value after 5 or 10min. recovery period. It is found that l changes in the following relation for cloths. _??_ (1)
where l_{_??_} is the value of l at t=o, a₁, a₂ and a₃ are the constants, t the time of recovery, and λ₁, λ₂ and λ₃ are the relaxation times.
In the case of yarn two relaxation times λ₁, λ₂ are given for recovery, and one relaxation λ₁ for filament. The values of λ₁, λ₂ and λ₃ are 50_??_70, 10_??_20 and 1_??_2min. in the case of the viscose yarn used.
In the range of t=3_??_20min., 160 samples of the cloths, which were woven variously by using the same viscose yarn, containing partly the resin-treated, are all indicated by the equation (1).

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In these reports, we studied by means of a spectrophotometer how the colour of the fabrics varies as the dyeing concentration (0.1%_??_5.0% w. o. f.) increases.
In Part (III), we examined the plots on the I. C. I. diagram, when acetate fabrics were dyed with an acetate dye. And in Part (IV) viscose rayon fabrics were dyed with a direct cotton dye. Fabrics were composed of bright filaments.
When both dyes are compared, the acetate dyes have in general higher purity, especially in blue, violet and green colours, while the direct cotton dyes surpasses the acetate dyes in the purity of the red.
In this report, acetate and viscose fabrics, consisted of 50% acetate fabrics, were dyed with a number of different colours, which were selected from many acetate and direct cotton dyes, with increased dyeing concentration (0.1%-5.0% w. o. f). The colour of the fabrics were analyzed by a spectrophotometer. Both types have no staining property to the other fiber; have the analogous colour property and also the similar colour fastness. The results are illustrated on the I. C. I. diagram.

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In the treatment of fiber with thermoplastic resin in liquid medium, the solvent is usually organic. If water solvent is needed, resin-water emulsion must be used, but this emulsion treatment is unsuitable for intra-treatment of fiber. We succeeded in intra-treatment of silk fiber with vinyl resin in aqueous medium using calcium acrylate monomer. Light resistance, strength and elongation of silk fiber by this treatment are reported in this paper.
Generally the tensile and flex strength of the fiber are superior to those of the thermosetting resin-treated. The light resistance is also higher than thio-urea treated fibers. The improvement of yellowing of the fiber treated with a somewhat concentrated solution of the acrylate resin is discussed.

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