ORGANIC POISONS AND DRUGS 101 



in a pure condition on anything like a large scale. The 

 complex mixture of the various phenolic hodies is commonly 

 known as cresylic or tar add, and finds several technical 

 applications. Creosote or tar dips are mixtures of tar acids 

 with the hydrocarbons that accompany them in the tar oils 

 with hydrocarbon oils, alkali, and resin soaps. Pyridine 

 bases derived from the coal tar are also present, and the 

 following is a good example of the composition of such 

 a dip :* 



It may be pointed out at this stage that the solubility of 

 carbolic acid in water is about 5 per cent., and that of the 

 cresols about 2| per cent. ; but that these compounds are 

 soluble in caustic alkalis, whilst the neutral hydrocarbons 

 are emulsified, yielding turbid opalescent solutions with 

 soaps. 



Based upon these principles is the preparation of such 

 disinfecting agents as creolin and lysol, which essentially 

 are feebly alkaline mixtures, having as their active princi- 

 ples phenols, and capable of forming emulsions by reason 

 of the resin or fatty soaps which they contain. In spite of 

 frequent claims to the contrary, all phenolic preparations 

 must be regarded vas poisonous ; thus with a carbolic dip 

 the dilution for use should be such that the phenols do not 

 exceed 0"75 per cent. 



Tar oil, or oil of fitch distilled from wood tar, resembles 

 creosote, but contains chiefly guaiacol and its allies. 



Oil of tar with vaseline, or mineral lubricating oil, is 

 a very common mange dressing fcr horses, and sometimes 

 finely divided mercury is also added. 



Crude creosote is very widely used for the impregnation 

 of wood sleepers and fence spiles. 



From all these sources, and even from tar itself, poison- 



* United States Department of Agriculture, Bulletin 107, 1908. 



