246 STERILIZATION, ANTISEPSIS AND DISINFECTION 



One part of nascent chlorine to 1,000,000 parts of water a milligram 

 to a litre in other words will kill moderate numbers of -bacteria 

 within a few minutes. For this reason, chlorinated lime is extensively 

 used in the treatment of swimming pools to reduce the bacterial count. 

 It is also used for the practical sterilization of urine, bath water, feces, 

 and in the solid state, in privies, cellars, and stables. 



Phenols, Cresols. Phenol, popularly known as carbolic acid, and 

 cresols, of which three are known ortho, meta, and para are powerful 

 germicides : 



OH OH OH OH 



^ CHl 



\/CHs 



CHs 

 Phenol Ortho cresol Meta cresol Para cresol 



Phenol and the cresols are somewhat sparingly soluble in water. 

 A 6 per cent, aqueous solution of carbolic acid, and 5 per cent, solu- 

 tions of the cresols are about the limits of solubility; 3 to 5 per cent, 

 solutions are used for most practical purposes. Phenol and cresols 

 are not only very toxic for bacteria, they are caustic and poisonous 

 for human, tissue as well. Stronger solutions are anesthetic, sugges- 

 tive of a definite action upon nervous tissue. These substances appear 

 to be readily absorbed from mucous surfaces, the skin, and wounds. 

 They are excreted, in part at least, through the kidneys. "Smoky 

 urine," indicating an irritation of the kidney tissue, is a not uncommon 

 sequel of carbolic acid poisoning. 



A 3 per cent, solution of phenol is approximately equivalent in its 

 disinfectant value to a 1 to 1000 solution of bichloride of mercury, 

 but it does not unite readily with proteins to form insoluble, inert 

 compounds, and it is not destructive of fabrics, metals and articles 

 of every-day use. 1 For sputum, urine, feces, purulent discharges, and 

 for stained and soiled linen, a 5 per cent, solution, equal in volume to 

 the bulk of the material to be disinfected, is used and allowed to remain 

 at least one hour before being disturbed. 



Cresols form soaps with caustic solutions, which are strongly ger- 

 micidal. An excellent cresol soap may be made by adding one part 

 by volume of cresols to an equal amount of soft soap (potash soap). 

 This is stirred thoroughly and allowed to stand twenty-four hours. 

 A 5 per cent, aqueous solution of this preparation is nearly three times 

 as efficient in its disinfectant value as a 5 per cent, solution of carbolic 

 acid. 



1 Hamilton, Therapeutic Gazette, 1914, xxxviii, 311. 



