STERILIZATION AND DISINFECTION 73 



It is not very penetrating and when employed to disinfect the 

 skin it must have considerable time (several hours) to act. 

 The alcoholic solutions are much more penetrating. As it is 

 very poisonous great care must be exercised in its use and in 

 properly labeling all bottles containing it. 



Carbolic acid (C H 5 OH) (Phenol). Pure carbolic acid 

 crystallizes in long colorless needles. At ordinary temperature 

 it is soluble in about 16 parts of cold water. A saturated solu- 

 tion contains from 6 to 7 per cent of the acid. Its value as a 

 disinfectant is increased by the fact that it acts in the presence 

 of albuminous substances. For disinfection it is commonly 

 used in solutions of from 3 to 5 per cent. In these strengths it 

 it destructive to all non-spore bearing bacteria. It is not 

 reliable for the destruction of spores and consequently should 

 not be used in the disinfection for anthrax, tetanus, malignant 

 edema and black leg bacteria. Carbolic acid is much more 

 penetrating than watery solutions of corrosive sublimate and 

 for that reason it is more valuable for skin disinfection pre- 

 paratory to operation. Dorset * sums up the advantages and 

 disadvantages of carbolic acid as follows. The advantages 

 are: 



(1) It is reasonably effective for destroying nonspore- 

 bearing bacteria. 



(2) Its action is only slightly interfered with by al- 

 buminous substances. 



(3) It does not destroy metals or fabrics in a 5 per 

 cent solution. 



(4) It is readily available at all pharmacies. 

 The following disadvantages may be mentioned: 



(1) It can not be depended upon to destroy the spores 

 of such bacteria as anthrax and malignant edema. 



(2) It is expensive (the pure phenol costs approximately 

 75 cents per pound) . 



Tricresol. Tricresol is a mixture of ortho-meta- and 

 para-cresols. It is a clear pinkish colored syrupy liquid. A 



Dorset. Farmers' Bulletin No. 345, U. S. Dept. Agric. 1908. 



