EVALUATION OF WOOD PRESERVATIVES 



157 



appears to be somewhat in excess of 7.5 pounds per cubic foot, whereas 

 the thresholds for the pentachlorophenol solution are somewhere between 

 2 and 3 pounds, and the threshold for the mixtures of the creosote and 

 the penta solution about 3.7 pounds per cubic foot. Duncan^^ gives 

 these respective thresholds as 7.5, 2.4 and 3.4 pounds per cubic foot. 

 Fig. 12 shows that when decay does occur as a result of attack by 

 Lenzites trahea, Mad. 617, the loss of weight in the wood is considerably 

 greater than in the case of attack by Lentinus lepideus. In the case of 

 Lenzites trahea, creosote appears as the best of the three preserva- 



1 23456789 10 11 t2 



TREATMENT RETENTION IN POUNDS PER CUBIC FOOT 



Fig. 11— Soil -block tests against Lentinus lepideus; weathered blocks; compari- 

 son of cooperative creosotes Nos. 6, 7, 8 and 11, and BTL No. 5340; based on 

 Madison data. The Madison treatment thresholds for these five creosotes were 

 set at 9.0, 9.0, 9.4, 6.5 and 7.5 Ib/cu ft, respectively. See Table VIII and Bibliogra- 

 phy, References 39 and 41. 



