COAL-TAR AND WATEE-GAS TAR CREOSOTES. 49 



anthracene do to one another. In general, the tar bases, particu- 

 larly the cyclic compounds, are toxic to bacteria and fungi, and 

 have been used as antiseptics in mediciue. So far as the author is 

 aware, no systematic tests have ever been made on the amount of 

 tar bases which might be expected in coal-tar creosote. It probably 

 does not, however, exceed the amount of phenols or tar acids. 



In addition to the various hydrocarbons, tar acids, and tar bases, 

 smaller amounts of compounds containing sulphur have been found 

 in coal tar. According to Lrnige (10), the following sulphur com- 

 pounds have been found in coal tar, and in all probability are present 

 in the creosote oil: thioxene, trimethyithiophene, tetramethylthio- 

 phene, biophene, dithienyl, trithienyl, thionaphthene, thiophthene. 



CHEMICAL PROPERTIES OF COAL-TAR CREOSOTES. 



A comprehensive treatment of the chemical properties of the 

 individual compounds found in creosote is outside the scope of this 

 work, and reference is made for this information to the various text- 

 books on advanced organic chemistry. A few remarks, however, 

 on the general reactions of creosote oil are desirable. In general, 

 the reactions of the various reagents which may be applied to creosote 

 oil are those expected of the aromatic hydrocarbons. Practically 

 all of the hydrocarbons in coal-tar creosote have the capacity of 

 forming beautifully crystallized addition compounds with picric 

 acid. All the aromatic hydrocarbons are attacked by fuming sul- 

 phuric acid, and some of them by ordinary sulphuric acid with the 

 consequent production of sulphonic acids, which are soluble in water. 

 The tar acids are characterized by their solubility in caustic soda, in 

 which they form sodium salts that are more soluble in water than in 

 oil. The phenols themselves can be reprecipitated from the aq^ueous 

 solution of the sodium salt by the addition of an acid, carbon dioxide 

 being sufficiently strong to accomplish this result. The tar bases, 

 as a rule, form addition products with the mineral acids at ordinary 

 temperatures, and these addition products are soluble in water. 

 These bases are also characterized in general by the formation of 

 insoluble compounds with the noble metals and with mercury^ 

 75536°— 22 4 



