Microscopic observations were carried out in order to ascertain if the qualities of commercial rayon pulps can be related to the microscopically observable morphological . characteristics, and whether can we estimate the qualities of commercial pulps by a morphological observation.
In the past staining of the fiber was used as a most serviceable method in the comparing of pulp characteristics, and the detailed morphological observations rather neglected.
In our observations on some Japanese and American rayon pulps, morphological differences were easily detected either by the ordinary microscope or by the polarization microscope. The most important characteristics in morphological aspects which we emphasize are the pits of the pulp fibers ; for example, the pit annuies were rather easily seen by staining methods on the Japanese rayon pulps, but they were not found on high a rayon pulps such as Rayonier and Rayocord. Width of pulp fibers is also one of the valuable characteristics. High a pulps have smaller width, and Japanese ordinary rayon pulps have larger width.
From the results observed under polarized light, Rayonier and Rayocord pulps were found to have larger “Retardation” value, while one of the Japanese rayon pulps was found to have lower value, and unbleached pulp to have the smallest retardation value.From these observations we can conclude that the refining and purifying procedures of pulps presumably affect the fine structure of pulp fibers.

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We have obtained the following results by the neutral sulphite semichemical process for birch wood ; the time of cooking, the maximum cooking temperature and the ratio of chemicals Na₂SO₃ and NaHCO₃were 60 min., 160°C and 8 : 34 : 1 respectively.10%, chemicals (calculated as Na₂CO₃) against the chip quantity was sufficient for the cooking. Better results were not obtained by using the larger quantity of chemicals with the same temperature and cooking time. When the total quantity of chemicals (calculated as Na₂CO₃) was equal, better cooking results were obtained as the quantity of Na₂SO₃ increased.
From this fact, it can be reduced as far as possible, if the cooking liquor does not become acidic at the end of cooking. The yield of pulp was not much influenced by the quantity of chemicals, and was 7080% of chip.
The chlorine absorption number was also not much influenced by the quantity of chemicals and was about 16.0 of the pulp. a-cellulose content of the pulp was 63-65%, and it means that 45-50% of chip remained intact as resistant cellulose in the pulp.
Similar results were obtained with beech wood and bass wood.

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We studied the conditions to meet staudinger's law of viscosity in cuprammomium solution and got some knowledges : cuprous chloride prevents the oxidation and decomposition of cellulose.But for wood pulp it must be added more than 25gr/l having no connection with thesorts of pulps and composition of cuprammonium solution. We can measure the degree of polymerization of wood pulp simply and accurately with the apparatus we have devised.

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The rosin size mainly causes three troubles in paper mills . The three troubles are given as under : 1) the difficulty of saponification, 2) the pitch trouble, 3) the paper colouring by the rosin size.
As the Japanese pinegum rosin (from Pinus densiflora or Pinus Thumbergii) often contain the crystals of resin acid, the size solution from these rosins contain unsaponifiable crystal masses. These crystal masses adhere to the smoothing roll of the fourdrinier maschine, and injure the smoothness of the paper . As the melting points of rosin crystals show 128-147°C, it is difficult to saponify completely, and they remain as masses of unsaponified rosin in the size. The capillary tube method is advised to determine the melting points of these crystal rosins. To avoid the trouble, the melting points of rosins should be 65-75°C.

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