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BELL SYSTEM TECHNICAL JOURNAL 



not against Porta incrassata. The latter fungus completely disintegrates 

 both the treated and the untreated wood. Despite the fact that the wood 

 treated with mixture 2 represented the highest concentration of any pre- 

 servative used (2.8 pounds per cubic foot), complete disintegration of the 

 wood 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 with 

 Greensalt K contains three chemicals in the following proportions: 



After treatment of the wood with this solution, reduction of the chromium 

 by the sugars in the wood together with evaporation of water precipitates 

 in the wood fibers several complex insoluble salts, among which presumably 



< 60 



COPPER ARSENATE 



COPPER DICHROMATE 



GREENSALT K 



1.36 0.45 0.91 U6 



POUNDS PER CUBIC FOOT 



1.36 



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 assay 

 of wood treated separately with solutions of these two components and with 

 the whole Greensalt K complex are given in Fig. 7. Before exposure to the 

 fungi, the wood specimens were leached by a diffusion method described by 

 Waterman, Leutritz and HilP, 1938. No untreated control blocks were 

 included in the bottles with this test, which was conducted for 24 weeks. 

 The copper arsenate component of the Greensalt K complex is shown to be 

 much more effective as a preservative than the copper dichromate component 

 but not as effective as the whole K salt complex. Figure 8 shows the setup 

 for the wood-soil assay of 0.75 Ibs/cu. ft. of Greensalt K from a recent series 

 of cooperative experiments conducted by the Forest Products Laborator)^ 

 Madison, Wisconsin. Figure 9 is a comparison of the Greensalt K treated 

 and untreated reference blocks in the same bottles after exposure to the 

 following fungi: 



