76 



Table 29. 



BULLETIN 1036, U. S. DEPARTMENT OF AGRICULTURE. 



-Comparison of the percentages of distillates of the creosotes whose toxicities 

 ti ere compared by Weiss. 



Fraction. 



Up to 200° C 

 Up to 235° C 

 Up to 270° C 

 Up to 315° C 



Straight 

 coal-tar 

 creosote. 



6.6 

 60.3 

 76.5 

 86.2 



Main- 

 tenance 

 of way 

 creosote. 



33.2 

 60.5 



78.0 



Neutral 

 coal-tar 

 creosote 



sp.gr. 



1.037. 



1.8 

 30.6 

 63.4 



87.2 



Water- 

 gas-tar 

 creosote 

 sp.gr. 

 1.024. 



1.1 



18.9 

 50.2 

 81.4 



"Water- 

 gas-tar 

 creosote 

 sp.gr. 

 1.053. 



5.3 



24; a 



49.0 



All the coal-tar creosotes, even the neutral creosote, had lower 

 boiling points than the water-gas creosotes, and consequently they 

 should be more toxic than the water-gas-tar creosotes. 



Tests made at the Forest Products Laboratory indicate that water- 

 gas-tar creosotes, particularly the lower boiling ones, have a con- 

 siderable degree of toxicity. A relation of toxicity to volatility 

 similar to that found in coal-tar creosotes holds in the case of water- 

 gas-tar creosotes also, except that the latter are not as toxic as the 

 former, particularly so in the higher boiling oils that are analagous 

 to carbolineums. The relation between toxicity of wat€a'-gas-tar 

 creosotes and their volatihty is shown in figure 36. # 



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Fig. 36.— The relation between volatility and toxicity of water-gas-tar creosotes. 



