COAL-TAR AND WATEE-GAS TAR CREOSOTES. 21 



In this country there is little demand for either carbolic oil or 

 anthracene oil. In general, therefore, these fractions are included 

 in the creosote oil, and for the most part only three fractions are 

 taken, namely, light oil, up to 200° or 210° C; creosote oil, up to 

 pitch; and pitch. The distillation is not carried so far as it is in 

 Europe, but is run only to soft pitch. It is, therefore, expected that 

 American oils will, in general, be somewhat lighter in specific gravity 

 than the European oils, because the carbolic oils are usually included, 

 and the distillation is not carried to so high a temperature. 



It sometimes happens, however, when the demand for pitch is not 

 very great, or when a special oil is desired, that the tar is distilled 

 until only coke remains in the still. The coke, which is a very pure 

 carbon, finds a sale for purposes similar to those for which retort 

 carbon is used. The creosote, in consequence of the high temperature 

 used in this distillation, is very high boiling and has a high specific 

 gravity. There are at least two plants in this country which make 

 special oils in this way. 



Creosote oil, as it appears on the market, is not always a product 

 obtained by the straight distillation of tar. It is frequently mixed 

 with other products of coal tar, which are not of any value in other 

 industries. For instance, the oil obtained by pressing the anthracene 

 cake frequently finds its way to the creosote-oil tank, as does also the 

 phenanthrene which results from the purification of the anthracene 

 cake. The high-boiling oils known as carbolineums are, essentially 

 expressed, "anthracene oils," In this country, tar is sometimes 

 added to light creosote oils to raise their gravity. This tar may be 

 either water-gas tar or low-carbon coal tar. The light creosote oils 

 are sometimes redistilled, to remove part of the light oil and naph- 

 thalene and thus produce an oil that will fulfill specifications otherwise 

 not met by the total distillate. 



The amount of material classed under ''creosote" that was pro- 

 duced, imported, and used in this country is shown by Table 7, 

 covering the last nine years. These figures mclude not only straight 

 distilled products of coal tar, but, in all probability, water-gas-tar 

 creosotes, mixtures of water-gas-tar creosotes and coal-tar creosotes, 

 and mixtures of either or both with coal tar, either refined, filtered, 

 or crude, as well as mixtures of either or both with water-gas tar. 

 No estimate of the amount of these mixtures can be made. 



