EVALUATION OF WOOD PRESERVATIVES 489 



(unpublished data). In two separate series — 1937 and 1938 — %-inch 

 stakes were treated at retentions slightly below the threshold cited by 

 Duncan^^ with o per cent solutions of pentachlorophenol in light petro- 

 leum (gas oil) and with two coal tar creosotes. The performance after 

 six and seven years was approximately the same for both the penta 

 solutions and the creosotes. However, completely favorable results on 

 test posts have been reported for Gulfport^^ and Saucier, Miss., test 

 plots. Early tests on 2 x 4 inch stakes are now being critically examined, 

 and more tests are in progress. ^^ Penta treated posts are installed in the 

 Saucier plot, where they are under periodic observation and comparison 

 along with posts treated with the cooperative creosotes. ^^ All of these 

 experiments will greatly facilitate correlation of the results of different 

 test methods. 



As far as pole line tests are concerned one can only echo the report^^ 

 that up to this time not one of the tens of thousands of poles in Une that 

 were treated with either straight penta-petroleum or with mixtures of 

 penta-petroleum and creosote have been reported as failing because of 

 decay. 



Swedish Creosote Evaluation Tests 



Rennerf elt and Starkenberg^^ report that of fourteen stakes measuring 

 1.5 X 1.5 X 100 cm, that were cut from the middle and inner sapwood of 

 creosoted Scotch pine poles, none are sound after ten years in the test 

 plot (May, 1950). The stakes were rated as 3 with sHght decay, 8 with 

 medium decay, and 3 with severe decay. Apparently these results cannot 

 be correlated with definite treatment retentions. 



On the other hand, the same authors state that stakes measuring 

 2 X 5 X 50 cm, treated to an average retention of 5.55 pounds per cubic 

 foot of creosote (undiluted) have all decayed in a 4.5-year exposure 

 period in greenhouse decay chamber tests. Additional experiments have 

 been started, presumably with stakes at higher retentions, ''in order to 

 determine whether it is possible to correlate results from such decay 

 chamber experiments with the results obtained in field and service tests." 



In another series of experiments Rennerf elt and Starkenberg find after 

 seven years (as of May, 1950) that creosoted stakes measuring 2x5 

 x 50 cm are showing different degrees of resistance to wood-destroying 

 fungi in their four different test plots. The difference in behavior in differ- 

 ent test plots — w^hich is more or less to be expected — holds true for 

 salt as well as creosote treatments. Creosote and Bolidens (zinc-chro- 

 mium-arsenic) are the better performing preservatives, with creosote in 



