EVALUATION OF WOOD PRESERVATIVES 487 



ran from a low of about 5.5 pounds to about 11.0 pounds. The wood had 

 apparently remained sound. Alleman cites the difficulties of arriving at 

 precise judgments but concludes ''that 10 pounds of creosote per cubic 

 foot is ample for railroad ties, and that piles require from 10 to 20 

 pounds" according to location. 



Alleman 's discussion of the relative amounts of light and heavy oil that 

 might be desirable are not applicable to present day oils and commercial 

 conditions. His perplexities remain — in almost identical form or in mod- 

 ernized version — and his extraction results are a long way from those 

 reported by Lumsden/^ and those cited elsewhere in this paper. Bre- 

 azzano was beginning the application of biological tests in Italy^^ with 

 a view to correlating chemical and fungicidal characteristics of preserva- 

 tives. This type of endeavor was later to be pressed vigorously by Bate- 

 man,^ whose work has already been mentioned. 



If the interpretation offered is supported by additional experiments 

 already under way the Madison data in Table XXXV and Figs. 34 and 

 35 mil be recognized as representing one of the most consistent series of 

 laboratory tests for the evaluation of creosotes that has ever been run. 



The Evaluation of Greensalt 



The satisfactory performance of posts and poles treated Avith green - 

 salt' ' has been reported in Lumsden's paper.' So far the very satis- 

 factory results at the Gulfport test plot are accurate indices of what has 

 been found by examination of poles in line. The only data on greensalt 

 treated J-^-inch stake tests reported in this paper are shown in Table 

 XII and Figs. 19 and 23. Summaries of additional stake data are now 

 in preparation for publication. 



The indications are that the threshold for greensalt under Gulfport 

 conditions is 1.42-2.1 pounds per cubic foot for J^-inch stakes. The 

 average life estimates for the two treatment groups — 0.57 and 1.17 

 pounds of dry salt per cubic foot — ■ (Table XIII) compare most favor- 

 ably with the estimates for the four creosotes in the same table. The 

 number of greensalt specimens is large enough to warrant the conclusion 

 that the lines used for estimating the threshold in Fig. 23, in their trend 

 to fall off to the right soon after the sixth year of exposure, indicate that 

 particular period as a critical .one for comparisons and interpretations. 

 Commercially treated southern pine poles meeting the standard specifi- 

 cation requirements for retention — 1 pound of dry salt per cubic foot — 

 have about 2.0 pounds of dry salt in the outer inch. The agreement be- 

 tween the stake and post tests seems good. 



