Soil-Block Bioassay of a Creosote Containing Pentachlorophenol

Tests described in this article were initiated to determine the wood-preserving qualities of a coal tar creosote in which pentachlorophenol crystals had been dissolved. The creosote selected for the study was an English vertical retort, coal tar creosote designated herewith as Creosote No. 9. A weighed amount of the creosote was heated in a covered beaker to 140?F and enough recrystallized pentachlorophenol added to give a pentachlorophenol concentration of approximately 2.0 percent by weight. A chloride determination was run on the creosote without penta as well as on the solution. The results of these analyses showed that the addition of about 2.0 percent pentachlorophenol to Creosote No. 9 increased the effectiveness of the creosote about 50 to 60 percent in terms of the test fungus Lentinus lepideus (Madison 534), and 20 to 25 percent in the case of Lenzites trabea (Madison 617). The fact that a one pound higher threshold was obtained with Madison 617 suggests that with a solution of creosote and pentachlorophenol, the highest threshold is obtained with Madison 617, and so it is the critical test fungus. These preliminary studies indicate that if pentachlorophenol is added to a creosote, a substantial increase in the effectiveness of the creosote may be expected.

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