COAL-TAR AND WATER-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 medicine. 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 Lunge (10), the following sulphur com- 
pounds have been found in coal tar, and in all probability are present 
in the creosote oil: thioxene, trimethylthiophene, 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 aqueous 
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 
