PENETRATION AND DECAY 377 



Discussion and Interpretation of Results 



In reading: the following discussion and interpretation of results it 

 should be remembered: 



(1) That the poles came from representative areas of the pine forest 



and from representative treating plants of the South ; 



(2) That all of the poles inspected were treated in accordance with 



the process specifications covering a full-cell treatment and 

 calling for a net retention of at least 12 pounds of creosote 

 per cubic foot of wood in the charge ; but related studies indicate 

 that the retention in individual poles probably varied from 

 less than 2 to more than 20 pounds per cubic foot; 



(3) That the poles were accepted if the treating process and the 



quantity of oil used conformed to the specifications; 



(4) That there was no required inspection at the time the poles were 



creosoted to determine the results of treatment in terms of 

 penetration and distribution of the creosote in the poles; and 



(5) That every pole inspected in the line was the original pole placed 



in the respective year designated. 



The evidence from the field data showed poor penetration to be 

 by far the most important cause of fungous infection and failure by 

 decay. As a matter of fact, the effect, if any, of geographical location 

 or of the type of creosote used was completely masked by the pene- 

 tration factor. 



On account of the wide geographical distribution of lines it was 

 expected that the effect of any definite climatic and meteorological 

 influences on the occurrence of decay would be apparent. It might 

 be expected, for example, that poles set along the warm, moist Florida 

 east coast would be more vulnerable than poles located in the drier 

 north temperate regions. However, the data in Table I for poles in 

 line 10 years or less are not conclusive as to the effect that geographical 

 location may have on the incidence of decay. 



The creosotes used conformed as a whole, or in their most important 

 characteristics, to the specifications in effect at the time the poles were 

 treated; but there was a fairly wide divergence in gross chemical 

 characteristics of the oils because of differences in the raw coal tar and 

 in the methods of distilling the tar. Table I includes data on the kinds 

 of creosote used, indicated by the fraction not distilling above 350° C. 

 or 360° C. The data are taken to mean that as far as internal sap- 

 wood decay is concerned, the type of coal tar creosote, provided it is a 

 true distillate of coal tar and that it conforms to the specifications, is 



