46 



BXILLETIlSr 1036, TJ. S. DEPABTMENT OF AGRICULTURE. 



bases. These may easily be added to a water-gas-tar product at 

 slight cost, however, and for this reason their presence is not proof 

 positive that the creosote in which they are found is of coal-tar origin. 

 It was supposed at one time that the color of the fractions was an 



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38 



1.00 l.0e .96 .9B 



SPECIFIC eRAViTY AT 60*C 



LOS L08 



Fig. 27. — Relation between the index of refraction values and the specific gravity of thef ractions of creosotes. 



Circles — Coal-tar creosotes. 

 Dots — Water-gas-tar creosotes. 



A. Fraction distilling between 255° and 265° C. 



B. Fraction distilling bctwwen 265° and 275° C. 



C. Fraction distillmg between 275° and 285° C. 



D. Fraction distilling between 286° and 295° C. 



indication of a mixture of water-gas-tar oils with coal-tar creosotes. 

 This investigation has shown that the supposed characteristic green 

 color of certain of the fractions is common to all creosotes or oils 

 having a high sulphonation residue, and that this color, therefore, 

 does not indicate a mixture of the two kinds of oil. 



