Method for application of agent, which is pregenerated from Borol by the aids of caustic soda and SO₂, on bleaching of high yield pulps was investigated in many ways. Although there was no problem on the characters of the generated bleach solution, the yields of sodium hydrasulfide (Na-HS) were fairly low in the range from 65 to 75% for the generating systems of batch operation or imperfactly controlled continuous operation. However, by a well controlled continuous system the yield rised to a value of 86%, and the bleaching effects on RGP and GP using the resulting agent were observed to be very satisfactory as compared to the results using powder Na-HS. NaBO₂, which is a by-product in the pregeneration reaction from Borol, was noticed to contribute positively to the bleaching effect, though the extent was not so large.

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The influences of the extractives present in eucalyptus woods from West Australia, marri (E. calophylla), karri (E. diversicolor) and jarrah (E. marginata) on the abnormal increases in viscosity of sulfate black liquors during evaporation were investigated.
The amounts of the extractives or kino were expediently represented by the kino indices for the difference of 72% sulfuric acid insolubles before and after alkali extraction, which were shown closely related to the pulp yield.
The increases in viscosities of concentrated black liquors were in the order of jarrah>marri>karri=domestic hardwoods. Especially the viscosity of the black liquors from jarrah had abnormally enhanced with evaporation. Such abnormal increases in viscosity could not be observed for the cases, where kino or kino components were added to the black liquors from the domestic hardwoods.
The addition of Ca-salt made an formation of precipitates in the black liquors from marri and the addition Mg-salt rendered the viscosity increase.
The increase of viscosity of black liquors were prevented by the alkali extraction of eucalyptus woods before sulfate cooking. On behalf of an alkali solution, black liquors from hardwoods were also effective for the extraction, but precipitates were formed, which were supposed to be the condensation products of kino and lignin. From the practical points of view, such extraction process were supposedly unfavourable.
Another countermeasure to prevent the increase in viscosity was the cooking process with a preheating period for the alkali extraction and decomposition of kino. The cooking liquors were added to the chips and kept for some interval under the temperature below 120°C, where no delignification took place and the extracted kino by cooking alkali could be decomposed. Such process were proven quite effective.
So far the sulfidity of the cooking liquor, the lower sulfidity was preferable for the lower increase in viscosity of black liquors, of which reasons might be interpreted from the rates of delignification and alkali decomposition of kino.

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The present status of waste paper utilization was discussed, since the ecological problems have attracted considerable attention in recent days.
Moreover, the trends of future utilization of waste paper were also discussed by taking its current status in America into account.
The following problems were discussed in this article.
1. collection and classification of waste paper.
2. storage of waste paper.
3. treatment of waste paper with an increasing output of converted papers.
4. diversification of waste paper utilization.
Furthermore, some technological aspects of waste paper treatment and the utilization of fibers in municipal refuse were reviewed.

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