. The Bell System technical journal . disintegratesboth the treated and the untreated wood. Despite the fact that the woodtreated with mixture 2 represented the highest concentration of any pre-servative used ( pounds per cubic foot), complete disintegration of thewood results from the action of the three fungi just mentioned. Compounds of the Greensalt type were also assayed by means of the soil-contact method. The solution commonly used for treatment of wood withGreensalt K contains three chemicals in the following proportions: Potassium dichromate K^CroO; 55% Copper sulfate CuSOi-SHoO 33
. The Bell System technical journal . disintegratesboth the treated and the untreated wood. Despite the fact that the woodtreated with mixture 2 represented the highest concentration of any pre-servative used ( pounds per cubic foot), complete disintegration of thewood results from the action of the three fungi just mentioned. Compounds of the Greensalt type were also assayed by means of the soil-contact method. The solution commonly used for treatment of wood withGreensalt K contains three chemicals in the following proportions: Potassium dichromate K^CroO; 55% Copper sulfate CuSOi-SHoO 33% Arsenic acid 11% After treatment of the wood with this solution, reduction of the chromiumby the sugars in the wood together with evaporation of water precipitatesin the wood fibers several complex insoluble salts, among which presumably < 60 COPPER ARSENATE COPPER DICHROMATE GREENSALT K o< o 50 t- o llj 1- 40 o UJ n- D UJ n 10 <n o T . ^ ^\ ^^^ 1^ \ \\ \ >.. 0 U6 0 POUNDS PER CUBIC FOOT Fig. 7—Comparison by wood-soil assay of components with the whole salt of Greensalt. Organisms Poria incrassata and Polyporous vaporarius. 24 weeks time. are copper arsenate and copper dichromate. Results of soil-contact assayof wood treated separately with solutions of these two components and withthe whole Greensalt K complex are given in Fig. 7. Before exposure to thefungi, the wood specimens were leached by a diffusion method described byWaterman, Leutritz and HilP, 1938. No untreated control blocks wereincluded in the bottles with this test, which was conducted for 24 copper arsenate component of the Greensalt K complex is shown to bemuch more effective as a preservative than the copper dichromate componentbut not as effective as the whole K salt complex. Figure 8 shows the setupfor the wood-soil assay of Ibs/cu. ft. of Greensalt K from a recent seriesof cooperative experiments conducted by the Forest Products Labo
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
