COAL-TAR AND WATEE-GAS TAR CREOSOTES. 



63 



the creosotes tested. Beyond the time of 304 days the blocks gained 

 in weight, probably because of the absorption of moisture. The 

 results of these tests are plotted in figure 31c, in which the ordi- 

 nates are the percentages distilling at 270° C. and the abscissae are 

























































































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PERCENTAGE LOSS 



C D 



Fig. 31. — Relation between the loss by evaporation and the per cent of 

 the oil volatile below 270° C. 



A. Loss of coal-tar creosote by evaporation from open pans. 



B. Loss of coal-tar creosote by evaporation from creosoted wood. 



C. Loss of coal-tar creosote by evaporation from pans and creosoted 



wood. Dots — Open pans. Circles — Maple blocks. Double 

 circles — Pine blocks. 



D. Loss of water-gas tar creosote by evaporation from open pans. 



the percentages of loss by evaporation. The three points lying in 

 the lines parallel to the abscissae are obtained by using the same 

 creosote in the three different methods of test. 



