86 BULLETIlSr 1036, U. S. DEPARTMENT OF AGRICULTURE. 



wood had been preserved from the fungus attack in some way or 

 other, although it apparently contained no creosote. Sections of 

 this untreated but preserved wood were taken, and any portions 

 that showed signs of containing creosote were carefully removed. 

 The remainder of the wood was then reduced to sawdust. A portion 

 of this was extracted with water in a Soxhlet extractor in such a 

 way as to retain the tar acids, if any were present, in the water. 

 Another portion treated in the same manner was extracted, but in 

 such a way as to retain the tar bases, if any were present. The solu- 

 tions thus obtained, upon being neutralized, gave odors similar to 

 those obtained from tar acids in the one case and from tar bases in 

 the other. A second extraction with benzol of the wood previously 

 extracted with water gave a residue of perfectly clear rosin, iix which 

 there was not the least sign of creosote odor. From this it seems 

 apparent that this inner ring of untreated material had been pre- 

 served by the water-soluble material that came from the creosote 

 and had been diffused through the wood. On the other hand, from 

 coal-tar creosote a high-boiling oil has been isolated, which is prob- 

 ably a mixture of anthracene, phenanthrene, acenaphthene, and 

 their hydrides. This oil is practically nontoxic, for fungus grows on 

 agar agar containing 20 per cent of the oil. 



The theory assumes that any toxic material which is more soluble 

 in oil than it is in water will be less toxic at the start if oil is present 

 than it would be in its absence. That is, if it takes 0.05 per cent of 

 some material in water alone to kill an organism, it might take as 

 much as 2 per cent if the material were dissolved in oil. On the 

 other hand, any reserve material would not be removed so rapidly 

 by leaching in the presence of oil as in its absence. Under similar 

 conditions the speed at which creosote wUl be rendered nontoxic by 

 leaching will depend on two things — the relative solubility of the toxic 

 oils in the nontoxic ods and m water and the proportion of non- 

 toxic oils present. If too little of the nontoxic oils is present, then 

 the toxic material will be washed away very rapidly, because there 

 would be little or no retaining influence exerted by the nontoxic 

 oils. On the other hand, if there is too large an amount of non- 

 toxic oil, the toxic oils wUl be prevented from going hito solution in 

 the water in a sufficient concentration to kill the attackmg organism, 

 and consequently these oils would not act as preservative. 



