COAL-TAR AND WATEE-GAS TAR CREOSOTES. 85 



before the concentration of the water is below the killing point, and 

 even then the water solution would still be very poisonous, though 

 not sufficiently strong to kill, for at least 30 more changes ot water. 



In actual practice this change may take place either rapidly or 

 slowly, depending upon the location of the treated timber. If the 

 timber is alternately exposed to wetting and drying, as is true of 

 piling between high and low tide, a very high rate of solution with 

 rapid depletion of the preservative material would be expected. In 

 timber located in dry places, as, for instance, telephone poles, a 

 very much slower rate of solution would be expected. The idea 

 here is simply that one part of the creosote oil prevents the rapid 

 solution of the other part of the creosote oil which is toxic and which 

 acts as the preservative. 



The information in support of this theory is as yet incomplete in 

 respect to creosote oil; but what information there is confirms the 

 theory. Historically, perhaps the first data available on the solu- 

 bility partition was furnished by Boulton in the Appendix of his 

 Antiseptic Treatment of Timber, in which he showed that tar acids 

 oould be washed out of creosote by water. This, of course, is true, 

 and according to the theory here proposed it is necessary if pro- 

 tection is to be afforded by tar acids. Boulton does not, however, 

 make a point of showing that, although he used only 20 ounces of 

 oil, it required 32 washings and the use of three times as much 

 water as oil, or a total of 1,920 ounces, to reduce the tar-acid con- 

 tent of the oil from 10 per cent to 1.5 per cent in one case, and from 

 17.5 per cent to 3.5 per cent in the other case. In other words, he 

 used 96 times as much water as he did oil, and even then he did not 

 remove all of the tar acids. The attack of the teredo on treated 

 piling after long service, during which the creosote acted as a pre- 

 servative, is certainly a sure indication that the action of the water 

 had dissolved out certain portions of the oil that were toxic. If 

 this had not been so, the teredo would have begun its attack imme- 

 diately. The very fact that creosote oil protected for a time and 

 then failed to protect is sufficient indication that the toxic element 

 had been removed. 



A better proof of the theory is shown by some recent investiga- 

 tions at the Forest Products Laboratory. In the course of a certain 

 study it was necessary to extract the creosote from a few telephone 

 poles that had been in service about 20 years. One of these poles 

 was so checked at the ground line as to permit the entrance of fungi, 

 and the entire center of the pole at the ground line was completely 

 decayed. None of the wood that contained creosote was decayed; 

 in fact, it was very noticeable that there was a ring of from. one- 

 fourth to one-half inch in the untreated wood just inside the treated 

 portion which was in a perfectly sound condition. This ring pf 



