A Procedure for Measuring the Volume of Small Wood Samples

Increment cores used to sample treated wood to determine preservative retention are often irregular in shape and calculated volumes are therefore questionable. A simple displacement method using a standard Babcock milk test bottle (converted to a tube 3-3/4 inches long with a capacity of 2 ml graduated in 0.02 ml increments) and petroleum ether (b.p. 30-60?C.) permits direct, rapid, and accurate volume determinations. Air is removed from samples by aspirating with mild vacuum while submerged in petroleum ether in a small test tube. After saturation, the sample is held with forceps to air dry from 5 to 10 seconds. It is then placed in the empty Babcock tube and exactly 1 ml of petroleum ether is added by pipette. After 10 seconds, the miniscus reading permits volume determination by subtraction. Comparisons between calculated and measured volumes of Douglas-fir and pine increment cores showed reasonable variation and, in some cases of very irregular cores, helped explain variation in subsequent determinations of preservative retention. All petroleum ether used in each measurement is poured into a crucible and evaporated with the sample to make certain any dissolved preservative is retained for the chemical analysis.

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