Relationship of Gas Phase Permeability to Ultrastructure of White Spruce Wood

Oxygen gas permeability measurements are used in calculation of the effective sizes of openings in the pit membranes of white spruce wood. A permeable apparatus was designed and used to measure longitudinal flow through dowels of 1 cc diameter and of 0.32, 1, and 3 centimeter lengths, at mean pressures from 6 to 70 cc mercury, and at constant pressure differential of 5 cc mercury. The slopes of regression lines were used to calculate the effective pore radii using a modification of Adzumi’s theory on the flow of gases through porous walls. Electron microscopic examination of samples showed great variation in the nature of pit membranes. The average width of the larger openings or pit membranes was in the same order of magnitude as the effective diameters calculated from the flow measurements. The results indicated that even in the shortest sapwood samples, only a fraction of the cell cavities participated in the conduction of oxygen gas.

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