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BELL SYSTEM TECHNICAL JOURNAL 



the relatively short period of three years, during which time all the specimens 

 have remained sound. 



Results of other field trials for a three-year period with the same mixtures 

 1, 2, 3, and 4, listed previously, copper arsenate, Greensalt 0, and a creosote 

 are given in Fig. 10. Twenty-five untreated controls showed 84% failure, 

 4% sound, and 12% badly infected in one year. All had failed at the end of 

 the second year. Twenty specimens were used for each retention of the 

 individual preservatives, with the exception of the creosote. The reason for 

 fewer creosote specimens within the correct retention is that the empty- 

 cell treatments of wood with creosote give a wider range of retention than the 

 full-cell treatments of the wood with water solutions of the salts. 



Twenty Four Week- 



Table 4 

 -Wood Soil Assay of Greensalt 

 Wood Destroying Fungi 



'0" Using 13 Species of 



Poria incrassala (16 wks) , 



BT.L. U-11 



Polyponis vaporarius .... 



Lenzites trabea 



Coniophora cerebella 



Trametes serialis 



BT.L. U-4 



Polvporus anceps 



B.f.L. U-53 



BT.L. U-24 



Lenzites sepiaria 



Poria micros pora 



Fames roseus 



Lentinus lepideiis 



Toxicity Index* 



1.17 Ibs/cu.ft. 0.96 Ibs/cu.ft. 0.476 Ibs/cu.ft. 



94 



98 



98 



98 



98 



98 



100 



100 



100 



100 



100 



100 



100 



100 



* Toxicity Index = 



% loss of norm — % loss of treated block 

 % loss of norm 



X 100. 



In the three-year period of exposure only the treatments of wood with 1 .3 

 pounds of copper arsenate and 7 pounds of creosote per cubic foot showed a 

 perfect record. Copper arsenate had previously been shown to be a very 

 efifective component of the Greensalt complexes when tested by the soil- 

 contact method. Mixture 2 was found to be the poorest by soil-contact 

 assay and also in the field trials. Mixtures 4, 1, and 3 were rated in that 

 order of decreasing effectiveness in the field test. In the soil-contact assays 

 at comparable retention, 0.72 and 0.80 pound of salt per cubic foot of wood, 

 respectively, mixture 4 was better than 1; and at 0.41 and 0.35 pound of 

 salt per cubic foot of wood, respectively, compound 1 was slightly better 

 than 3, especially against Poria incrassala. 



Results from field and laboratory tests show good agreement in the evalu- 



