COAL-TAR AND WATER-GAS TAR CREOSOTES. 5 



facture of petroleum products in competition with the natural Amer- 

 ican oils. It also contains phenoloids and tar bases. 



(2) Producer tars are those tars which are produced from bitumi- 

 nous or semibituminous coals in the manufacture of producer gas. 

 They result from destructive distillation combined with a partial 

 combustion of the coal, (a) Blast furnaces using coal are in effect 

 practically gas producers. A small amount of tar is produced in 

 them, but it is similar in composition to that made in gas producers. 

 This tar is known as hlast-furnace tar. (h) Mond-producer tar is 

 obtained from a Mond producer using bituminous or semibituminous 

 coal. Other bituminous-coal producers also yield tars. These are, 

 in general, called by the name of the producer, as the Sutherland 

 producer tar. 



Oil tars are the tarry fluids resulting from the destructive decom- 

 position or cracking of petroleum oils. Like coal tars, these fluids 

 are exceedingly complex mixtures. The character of their hydro- 

 carbons depends greatly upon the temperature at which the tars 

 were formed. 



Like the high-temperature coal tars, the high-temperature oil tars 

 are very complex mixtures of compounds. The hydrocarbons are 

 chiefly of the aromatic series. Benzene, toluene, naphthalene, 

 phenanthrene, and methyl anthracene have been found in them; but 

 so far as is known no true anthracene has been identified in the 

 American oil tars. They are further characterized by the almost 

 entire absence of tar acids and tar bases, and this seems to consti- 

 tute the chief difference between this type of tars and high-tempera- 

 ture coal tar. 



Water-gas tar is the tar produced from petroleum oil in the carbu- 

 reted water-gas machine. This tar is practically the sole represen- 

 tative of high-temperature oil tars. Very small amounts of high- 

 temperature oil tar are produced by the destructive distillation or 

 cracking of petroleum oils in the gas retorts. A sample of such tar 

 examined several years ago by the author could not be distinguished 

 from water-gas tar and could be distinguished from high-tempera- 

 ture coal tar only by its lack of phenoloids and tar bases. 



Low-temperature oil tars are produced in the manufacture of pintsch 

 gas and are obtained as a residuum in the distillation of petroleum. 

 They are characterized by an almost total absence of aromatic 

 hydrocarbons and by a lack of phenoloids and tar bases. No fur- 

 ther discussion of this class of tars is necessary for the purposes of 

 tttis bulletin. 



The term creosote is properly applied to the phenoloid bodies 

 obtained from wood tar after they have been freed from the hydro- 

 carbons, and the term is still used in this connection by druggists. 

 A secondary meaning for creosote applies to a similar product 



