The fact that the unbleached sulfite pulp gives a red color was recognized about thirty years ago.This phenomenon has been studied by several investigators on the softwood pulps, but not on the hardwood pulp.Though the unbleached sulfite pulp prepared from hardwood gives also a more or less distinct red color, the reddening of hardwood pulp some what differs from the reddening of softwood pulp.The reddening of softwood pulp appears in a course of storage, while the reddening of hardwood pulp appears immediately in a course of washing of pulp discharged from a digester.In this paper some studies are given on the reddening of hardwood sulfite pulp.
Sulfite pulps were prepared from seven kinds of hardwood (poplar, alder, birch, beech, oak, maple and lime), left for seventy hours to stabilize the red color appearing on the pulps and then the degree of reddening of pulp was determined by the EPIC spectrophotometer against a_magnesium oxide plate.
The red color of pulp was the most pronounced in cases of birch, maple, lime and alder. The red color gives a reflection minimum at ca. 500mp (Fig.1), though the red color of softwood pulp gives a reflection minimum at 510-520mp.It seems that this coloring matter is already produced on a half way of cooking period, and thereafter the two reactions, the production and the decomposition of the coloring matter take place simultaneously (Table 2).The deepness of red color is not always proportional to the lignin content of pulp.
The reddening of softwood pulp is considered to be caused by the lignosulfonic acid (or the product derived from it) in pulp.The same conclusion may be drawn from the following facts in case of hardwoodpulp. (1) The red color can be also observed on the pulp prepared from birch wood free from extractives (Fig.2). (2) The red color can not be observed on the pulp prepared from spruce wood (the spruce sulfite pulp gives not red color in the authors' experiment) impregnated with the extractives of birch wood. (3) The pulp prepared from spruce wood impregnated with the solid lignosulfonic acid obtained from birch wood, gives a pink color.The presence of heavy metal ion promotes the reddening of pulp (Fig.3).Bleaching powder and sodium chlorite are effective to remove the red color appearing on pulp (Fig. 6).The color can be also removed by treatment of hot water or aqueous solution of sodium hydroxide whose concentration is more than 5 milli molg.

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Alkaline degradation of protolignin using aqueous sodium hydroxide were studied in an attempt to obtain some clearance on lignin chemical structure.Of these degradation products four phenolic compounds were isolated and identified through tedious procedures vanillin, vanillic acid, acetovanillone, guaiacol and 3, 3'-dimethoxy-4, 4'-dioxy-stilbene.
Identification of the fourth compound led us to reconfirm I.A.Pearl's suggestion that a linkage exist between the a-carbon atoms of two phenylpropane units in at least a part of the protolignin structure.

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In Ca-base sulphite cooking of larch (Larix leptolepsis Murray) heart wood chip, it has been investigated how various techniques promoting penetration of cooking liquor improve the cooking results.The results obtained are as follows.
1.Effect of high concentration cooking liquors.Relating to the concentration of combined acid, its effect was investigated within the range from 1.0 to 1.7% at the same concentration of free acid (7%) and liquor to wood ratio of 6.Comparatively great improvement was found by increase of the acid from 1.0 to 1.2%, but increase over 1.2 % had not any improvement in the results.Increase of free acid brouht noticeable improvement.Under the concentration used in this study, the best pulping results was obtained with the liquor of 6.5 ro free acid and 1.5 ro bombined acid (Screenins/pulp : 20.1%, Cl₂ consumption : 7.7%, see Table I)
2.Effects of steeping chips in water, presteaming or Va-purge pretreatment.These pretreatments showed substantial improvement.Presteaming (for 4 mins.by 2.5 kg/cm2 steam) and Va-purge pretreatment (3 times for 1.5 mins.by 2.5 kg/cm2 steam) showed identical results that screensngs/pulp was ca.10% and Cl₂ consump.7.5%.Under the conditions used, the better next to the above pretreatments was steeping chips in water under reduced pressure (screenings/pulp : 12.1%, Cl2 consump. : 8.74%) followed by vacumimpregnation of cooking liquor (screenings/ pulp : 16.4% Cl₂ consump.7.25%).Steeping chips in water without evacuation showed little improvement compared with regular pulping. (see Table I andIII)
3.Although the above techniques brought considerable improvement in the pulping results, they were much inferior to the use of soluble bases such as Na and NH3 by which sceernings was only about 2 % of screened pulp and Cl2 consumption of the pulp ca.4%.
4, From curves of delignification and thiosulfate and sulfate formation during cooking, it has been deduced that, besides the decomposition of cooking liquor by taxifolin, slowness of delignification in sulphite cooking of larch heart wood is another substantial cause of difficult pulping of the wood.The slower delignification may be caused by difficult penetration of the wood.

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A sample of half-bleached sulfate pulp (sample A) is bleached by means of chlorite (sample 13) and hypochlorite (sample C) respectively.D.P.distribution of these three samples is determined by the summative fractionation method, using cupri-ethylenediamine as solvent.The results obtained show that thoug the chlorite bleaching also shortens somewhat the chain lengths of cellulose the shape of distribution curv of (B) resembles to that of the original pulp (A), while the hypochlorite bleaching degradates the highe D.P.portion remarkably.
The summative fractionation method is approved as more convenient for the approximate estimation samples of alike species.

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From previous report, by vibrating reed method, we can also obtain Young's modulus and viscosity of paper'
According to simple mathematical consideration, we can correlate it with theoretical equation derived from parallel linked Maxwell element, assuming distribution function of relaxation time at logarithmic scale is constant.
From this consideration
1) Youngs'modulus at vibrating reed method is apperent.Youngs' modulus or Youngs modulus at strain is zero in stress-strain curve with constant rate of elongation.
2) η from vibrating reed method from 20 c.p.s.to 100 c.p.s.is propartional to second elastic constant K in stress-strain curve with constant rate of elongation within 1 % strain.
In this equation 12 of 10⁶∼10⁷ order poise at 20 c.p.s.∼100 c.p.s.correspond to 10¹².∼10¹³ poise order viscosity at 10-⁵/sec order rate of elongation assuming 3 element model which is composed of 2 springs and one daslipot for paper.
3) η change at vibrating reed metho d varying frequency corresponds to change of K varying rate of elongation, that is K=B/2α (1/τ₁-1/τ₂) where B is contant α, rate of elongation τ₁, τ₂ relaxation time but it does not fit quantitatively experimental data
Let us take following two assumption
a) τ₂/τ₁=k ατ₁=constant when α is varied
b) τ₂/τ₁=k ατ₁=k₁α1/n when α is varied
k, k₁ constant n, constan n>1
from a) stress is independent of a it does not fit experimental data.
from b) S=γBl_nk-B2k₁α¹/n k-1/k
when τ₁>t<<τ₂ t=τ/α
S=γB((1-C+l_nk+l_nk₁)-k_nγ+1/n l_nα)
when τ₁<<t<<τ₂
these equations fit experimental data considerably qualitatively from Andersson and sjoberg, and from b) η (reed method) -υ (frequency) relation explains well experimental data.
4) from b) S-α plot represent the flow type of paper and it is concluded that paper has flow type of pseudo-plastic or plastic flow where strain is small
1) Y. Fujii : Japanese Tappi Vol.10.No.1
2) O. Andersson and Sjoberg : Svensk Paperstidning 1953 16 Aug.

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Alkali solubility
The methods CCA8 : 53 and Merkblatt IV/29 were investigated in detail as reported before, but at present the industry of Japan has no positive intention of adopting CCA8 : 55 or Merkblatt IV/29B/55 or any other similar methods as the standard.The Committee of Japan, however, is not indifferent about these methods, for alkali solubility tests continue to excite the attention of several research laboratories.
CED or CAM
The dissolving power of both the solvents and the stability of cellulose against depolymerization in them were measured.When the two-stage dissolving procedure is used, cupriethylenediamine has a greater dissolving power than cuprammonium for samples of cellulose having medium degree of polymerization.It was observed that cellulose is far more stable in cupriethylenediamine than in cuprammonium.These tests were done at such concentrations that the product of intrinsic viscosity and concentration equaled three.
Flow behaviors of cellulose solutions
To secure some scientific background which might be helpful to authenticate or revise the methods for viscosity determination, the flow curves of solutions of cellulose varying in degree of polymerization in cupriethylenediamine and in cuprammonium were investigated.A capillary viscometer with continuously varying pressure head as designed by Maxon, Krieger and Sisko (J. Appl. Phys., 25, 971 (1954)) was constructed and improved so as to be used in oxygen-free atmosphere.The viscosities of non-Newtonian fluids were obtained from the ratio of shearing stress against rate of shear at any points on the flow curves.
The solvents, cupriethylenediamine and cuprammonium, are practically Newtonian.Whereas, the flow curves of cellulose solutions begin to deviate from linearity when the concentration exceeds a certain limit.The higher the degree of polymerization, the lower the limit concentration.The influence of rate of shear should be considered, when intrinsic viscosities are to be determined by the extrapolation of log (ηsp/c)-c plots.
One-point method
The one-point method as suggested by Wetzel, Elliot and Martin (Tappi, 36, 564 (1953)) and recently intended for practical use by Wilson (communication) gives intrinsic viscosities which are very conformable to those determined by the extrapolation method, so far as the degree of polymerization is not too high.The values were compared with those measured by the original Staudinger method.She differences are not too much.
The one-point method was tested also with cupramonium solutions.In various standard methods cuprammoniums varying markedly in composition are used. The constant k' of Martin's equation is sensitive to the copper content of the cuprammonium. If the proper value of k' is used, the one-point method affords very agreable values of intrinsic viscosities also for cuprammonium solutions of cellulose. The magnitudes of the constant to be used are : 0.30 for ACS, 0.31-0.32 for TAPPI and 0.35 for JIS cuprammonium.

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