A Study of Certain Factors Influencing the Movement of Liquids in Wood

Abstract

Early workers in the fields of plant anatomy and physiology did not believe there were any direct openings between the cells of wood. To explain the movement of viscous organic substances, preserving oils for example, Tiemann (21) advanced the hypothesis that the wood was made permeable by checks which developed in the cell wall during seasoning. Weiss (22) modified this hypothesis to explain why a greater penetration of preserving oils was obtained in the dense summerwood of longleaf pine. Information was later submitted by Bailey (1, 2) which led him to conclude that the intercellular movement of preserving fluids was through small openings in the pit membranes. Scarth (14), after an examination of coniferous wood impregnated with mercury, also concluded that the effective intercellular communication was localized in the bordered pits.Assuming that the pit membrane pores were the means of intertracheid flow, Stamm (15) has used physical methods to obtain the dimensions of the pit perforations. The range in average diameters (of true circles having the same effect as the openings of unknown shape) of the pit perforations in two species was found to be 11 µ to 23 µ. The range in maximum diameters for five woods was found to be 68 µ to 184 µ. Stamm (16) also has recently made determinations of the ratio of the effective capillary length to the effective capillary cross section of the pores in the pit membranes.

A method for measuring hydraulic conductivity and embolism in xylem

“…This decline, which can begin within the first minutes of measurement (Zimmermann, 1978), has been observed for xylem of several species under a variety of experimental conditions. Explanations include blockage by air coming out of fluid within the sample (Kelso, Gertjejansen & Hossfeld, 1963); narrowing of vessel diameters due to swelling of surrounding tissue (Jeje, 1986); eleetro-osmosis (Buckman, Schmitz & Gortner, 1935); particulate clogging (Krier, 1951); and swelling of intervascular pit tnembranes (Zimmermann, 1978). The second and less obvious problem with conductivity measurements is the potential presence of naturally occurring air-filled tracheids or vessels.…”

The mechanism of flow of gases through coniferous wood

“…The movement of liquids is generally the more im portant in these processes but, so far, direct investigation into the mechanism of liquid flow has not been very successful. This is primarily because wood is not an inert, physically stable, material bu t is believed to undergo changes in the structure and geometry of the flow channels during contact with liquids, particularly polar liquids (Buckman, Schmitz & Gortner 1935;Stamm 1935;Anderson, Gortner & Schmitz 1941), so th a t flow tends to be more complex than in other porous media. I t is not uncommon, for example, for flow to decrease asymptotically to zero under a constant pressure difference or to show a greater than linear proportionality to pressure difference (Anderson et al 1941; Kelso, Gertjejanson & Hossfeld 1963;Bailey & Preston 1969).…”

Studies in Wood Preservation. Pt. III. The Penetration of the Fine Structure of Wood by Inorganic Solutions, Including Wood Preservatives

“…Robinson and Stokes (1955) gave the radii of a few hydrated ions in aqueous Solutions, and by using 9 Holzforschung Bd. The addition of tetravalent thorium to Solutions containing lower valency ions is known to improve flow rates through narrow orifices (Bishop, Urban and White, 1931) because it depresses the thickness of the double layer, and this is related to the high flow rates of thorium chloride Solutions through baisam fir wood (Buckman, Schmilz and Gortner, 1935); this suggests that wood behaves äs a negative membrane. They ränge from about 2.9 Ä for potassium to about 5.0 Ä for tetravalent thorium, with the divalent and trivalent ions having hydrated radii between 4.0 and 5.0 Ä.…”