6 BIILLETIlSr 1036, U. S. DEPARTMENT OF AGEICULTTJEE. 



obtained from coal tar, and, in this respect it means the mixture of 

 phenoloids known to the wood preserver as tar acids. 



Creosote oil is the term correctly applied to that portion of wood 

 tar or coal tar from which creosote may be obtained by extraction 

 with caustic soda and a subsequent neutralization of the aqueous 

 liquors with mineral acids. 



Common usage in the wood-preserVing industry has led to the 

 disuse of the word "oil" and to the application of the term "creosote" 

 to the mother liquor, or crude oil, from which true creosote may be 

 obtained. Because of the similarity in other respects between the 

 oil obtained from coal tar — that is, the true creosote oil — and that 

 obtained from water-gas tar, the term "creosote oil" has been applied 

 to oils containing no phenoloids whatsoever. In this publication, 

 the term "creosote" is applied only to a pure product obtained by 

 the distillation of tars, and will be restricted to the oils obtained from 

 high-temperature coal and oil tars and to wood tars. They will be 

 further defined by the use of some qualifying word or phrase such as 

 coal-tar creosote or water-gas tar creosote. All the distilled oils 

 (except patented or proprietary articles) will be called oils or dis- 

 tillates, and suitably designated to show their derivation. Mixtures 

 of distilled oils with their mother liquor or with the mother liquor 

 from other distilled oils will be termed tar solutions. More specifi- 

 cally, these terms are defined as follows: 



Coal-tar creosote is defined as any and all distillate oils boiling 

 between 200° and 400° C, which are obtained from high-temperature 

 coal tars by distillation only. The addition or admixture of tars 

 from any mixture or som"ce, either refined, filtered, or crude, is not 

 permitted under this definition. 



Water-gas-tar creosote is defined as any and all distillate oils boiling 

 between 200° and 400° C, which are obtained from water-gas tar 

 or other high-temperature oil tars by distillation only. Admixture 

 of other materials than those stated above changes the nomen- 

 clature. 



Wood-tar creosote is a distillate oil obtained from wood tar. It has 

 a specific gravity greater than 1 and distills principally above 170° 

 C. at atmospheric pressure. 



Shale oil is the oil obtained from the distillation of shale tar. 



Mond oil is the oil from the distillation of Mond-producer tar. 



Petroleum oil is used in the ordinary meaning, but also includes 

 the oil from low-temperature oil tars. 



Retort oil is the distillate above 200° C, obtained from low- 

 temperature coal tars produced in the gas retort. It is similar in 

 composition to Mond oil. 



