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THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1953 



as great as those determined by the Boving evaporation experiments. 

 The columns have been numbered to facilitate reference. Attention is 

 directed to Columns 6 and 7, and to columns 11 and 12. It will be noted 

 that at the end of Time Period 1 the calculated amounts of material 

 boiling below 355°C in creosotes 2 and 8 are approaching the same 

 magnitude in the respective 8-, 10- and 12-pound treatment groups; and 

 by the end of Time Period 2 (columns 11 and 12), the calculated amounts 

 in each respective treatment group are practically the same for these two 

 creosotes that originally had residues above 355°C of 40.25 and 8.49 re- 

 spectively. Actually, of course, the time periods would not be the same 

 for the respective 8-, 10- and 12-pound treatments, but — • on the basis 

 of loss data already presented — would probably be relatively shorter 

 for the lower retention group and relatively longer for the higher reten- 

 tion group. 



Table XXXIII illustrates two methods of arriving at estimates of the 

 per cent and amount of creosote remaining in the respective fractions 

 above and below 355°C, by extraction data and by calculation of the 



Table XXXIV — Calculated Amount of Creosote Fraction 



BELOW 355°C Remaining after Various Exposure Periods 



UNDER Weathering Wheel Test Conditions 



Exposure period, weeks 



Treatment retentions — Ib/cu ft 



16.7 



Residual fraction below 355°C Ib/cu ft 



Creosote I 



Creosote II 



See text for significance of horizontal lines, page 485. 



