Abstract
To investigate the gas permeability in the radial direction in green logs of Cryptomeria japonica, the log specimen was prepared with both ends sealed and the log's bark removed. A glass tube was set in each end of the heartwood, white zone wood and sapwood sections. The specimen was then set in a vacuum chamber. Each of the glass tubes was connected to a separate mercury manometer set outside the chamber. The changes in pressures were then measured during the different stages under vacuum. The amount of exposure of the end section of the white zone wood was then varied, and the subsequent pressure changes were measured, alternating between the vacuum state and the atmospheric pressure state. Another experiment was carried out on some different specimens, in which the log's bark was retained, and the gas permeability between the white zone wood, sapwood and ambient atmosphere in the radial direction was investigated.
The results obtained were as follows.
1) The first detected decrease in pressure was in the white zone wood in both experiments, which demonstrated that there were radial passages through which gas flowed from the ambient atmosphere through to the intermediate wood, regardless of the presence or absence of bark.
2) Pressure variation in the sapwood was consistently affected by the gas flow from the white zone wood rather than from the log surface.
