木材のpHに関する研究(第3報) : 各種木材のpHと汚染について

There were measured the pH values of 120 species of Japanese wood, tropical wood and wood-based materials (laimnated wood of Birch and hardboard) and others by using the filtrate which was obtained from the mixture of 3 grs. of wood flour(air-dried condition) and 50 grs. of distilled water, with a pH meter with glass and calomel electrodes.
The list for these pH values were made on the basis of family and genus. (Tables 1, 2 and 3) Greater parts of the examined wood showed weak acidity as clear from the list. Particulary, wood showing from pH 5.0 to 6.0 accounted for 52.7% of all measured wood . (Fig. 1)
In Japanese wood, relatively low pH value was observed in Quercus (PH 4.6-4.9), and Ulmus gave the highest pH value (pH 7.0). (Table 1) Eucalyptus of tropical wood showed relatively low pH value (pH 4.3-4.9). The pH value of Dipterocarpaceae such as Apitong, Red lauan, White lauan and Meranti, was distributed mainly in the range of 5.0 and 6.0. (Table. 2)
In addition, the relation between the pH value of wood and its staining with ferric chloride on cross, radial and tangential sections was investigated. The staining with ferric chloride decreased in cross, radial and tangential section in this order. (Tables 1, 2 and 3) There was relation between the pH value of wood and its staining with ferric chloride in Japanese wood. On the other hand, there was no relation in tropical wood (Fig. 2 and 3) In Japanese wood, the most extensive staining was observed on Quercus, particulary Kashiwa (Q. dentata Thunb.).