165 



or destriicti\c effects upon li\'ini; organisms, it was felt tliat (lu- douMiiig of eflect 

 gained hy lioth adding and subtracting the reciuired fractidii niiglit increase the 

 decisiveness of the results. 



An analysis was made of the oil from each run, as well as of that extracted from 

 one of the test pieces after treatment. The analysis of oils scion after treatment are of 

 no particular significance and are not given. 



After planting, the gates were ins|5ected from tinu' to time for signs of horer 

 attack. The bait [pieces were, in all cases, hea\ily attacked, and in some cases were 

 completely destroyed and had to be replaced. However, no direct attack was found 

 on the treated wood until January 1924, after an exposure of two and one-half years. 

 At this time, slight Limnoria attack was discovered on two of the pieces in the gates 

 at Oakland Mole. These two were the pieces treated, respectively, with fraction B 

 and fraction I). The attack was not yet severe enough so that these pieces could be 

 said to have completely failed. Furthermore, the same treatments at the other stations 

 were not attacked. It is possible that these pieces were not as well treated as some 

 of the others. 



At the time of this inspection, lO-inch lengths were cut from the test pieces 

 and the oils were extracted and analyzed. The results are gi\en in table 16. They 

 show nothing unexpected, with the exception of an ap(3arent relation between the 

 physical character of the extracted oil and the percentage of tar acids remaining in 

 the oil. Where the extracted oil contains a large proportion of solids, a greater per- 

 centage of the original tar acids remains in the oil. This is probably due to two causes. 

 First, an oil containing a large amount of solid matter olTers a smaller effective leaching 

 surface to the water, since it prevents, to some extent, penetration of water. Second, 

 the oils containing the larger amounts of solids are usually the higher boiling fractions, 

 and naturally contain higher boiling tar acids, which are less subject to leaching, 

 table 15 shows the relation between the amount of solids in the oil and the loss of 

 tar acids. 



TABLE 15 



RELATIONS BETWEEN LOSS OF TAR ACIDS AND PHVSKAL CHAR.ACTER 



OF CREOSOTE OIL 



Tar .Acids 



Original per cent 



Final per cent 



Difference 



Per cent loss of original 

 tar acids 



Small 



5.8 

 3 

 2.8 



48 



.\mount of Solids in Oil at Room Temperature 



7,5 

 3.9 

 3.6 



48 



Medium 



6 



3.8 

 2 .2 



37 



4.6 

 3.5 

 11 



24 



5.9 

 i.l 



2.7 



46 



6.6 



3.1 

 3.5 



53 



Large 



6.4 

 4 6 

 1.8 



28 



Solid 



6.0 



5.4 

 0.6 



10 



4.0 

 2.8 

 1.2 



30 



6.6 

 5.2 

 1.4 



21 



6.0 

 4.5 

 1.5 



5.1 

 4.4 

 0.7 



14 



In considering table 16 further, it is evident that there is a very considerable 

 loss of tar acids in all cases. This is not surprising when we find that there remains in 

 the wood practically nothing distilling below 235° C, and that a considerable pro- 

 portion of the tar acids ordinarily present distils below that point. Since these very 

 low boiling tar acids have no permanent value, it seems evident that the usual speci- 

 fication for tar acids can be considerably reduced, if it is limited to those distilling 

 abo\e 2.i5° C. In fact, it is the belief of the present authors that the percentage of 



