170 



The analysis of the original creosote and that recovered by extraction from treated 

 wood gave practically identical results. The effect of benzene on the oil was still 

 further tested by boiling a 50-50 mixture of benzene and oil under a reflux condenser 

 for three hours. Benzene was then added until it was 90% of the whole and the diges- 

 tion continued for ten hours more. The recovered oil was the same as the original oil, 

 as shown in table 19, although the treatment was far more severe than in any ordinary 

 extraction. 



TABLE 19 



EFFECT OF BOILING BENZENE ON CREOSOTE OIL 



Original Oil after Benzene 



, Distillation Oil Digestion 



Up to 210° C 0.2% 0.0* 



210-230° C 1.5% 0.7* 



230-250° C 7.2% 7.0 



250-270° C 12.8% 12.5 



270-290° C 10.7% 10.8 



290-315° C 10.4% 10.5 



315-355° C 16.1% 16.8 



Residue 41.1% 41.5 



*Small amount of loss in removing benzene. 



ANALYSES OF OILS AFTER EXPOSURE IN TREATED WOOD AND OPEN DISHES IN 



Original 

 Oil 



Time exposed 



Loss 



Specific Gravity 1 .059 



Tar Acids 10.7% 



Distillation: 



Up to 210° C 1.5% 



210-230° C 9.5% 



230-250° C 16.5% 



250-270° C 12.6% 



270-290° C 8.1% 



290-315° C 8.2% 



315-355° C 16.4% 



Residue 27.2% 



Table 20 gives the composition of the recovered oils after exposure for some time, 

 in treated wood and in open dishes, in the air. Table 21 gives the results for the oil 

 from treated wood exposed in sea water. 



The composition changes found in the oil in this series of tests are practically 

 the same as those found in the earlier experiments. The loss falls on the low boiling 

 fractions, and a considerable portion of the tar acids is lost. The chief difference 

 between the oils extracted from the water-exposed and air-exposed pieces lies in the 

 percentage of tar acids. The rate of loss of tar acids from treated wood in water is 

 greater than from treated wood in air, in spite of the fact that the rate of loss of the 



