434 



THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1953 



pounds per cubic foot for the respective groups. Two groups of stakes 

 treated with greensalt K^^-^^ at 0.57 and 1.17 pounds per cubic foot, 

 respectively, are included in the table for comparison. 



Depreciation curves for the 4- and 8-pound groups for the four creo- 

 sotes are shown in Figs. 19, 20, 21 and 22. A depreciation curve for 

 greensalt K specimens treated with 1.17 pound per cubic foot is included 

 in Fig. 19. 



Estimating Threshold Retentions and Average Life 



In presenting the following discussion of a theoretical approach to the 

 estimation of threshold retentions and average life no attempt has been 



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TREATMENT RETENTION IN POUNDS PER CUBIC FOOT 



Fig. 18 — Distribution of ratings in relation to retention by weight at treatment; 

 creosote No. 6283, full-cell treatment (toluene dilution), seven years exposure. 



