THE DESTRUCTION OF BACTERIA 77 



Among organic disinfectants those of most practical importance are 

 the alcohols, formaldehydes, iodoform, members of the phenol group 

 and its derivatives, carbolic acid, cresol, lysol, creolin, salicylic acid, cer- 

 tain ethereal oils, and, more recently introduced, organic silver salts 

 such as protargol, argyrol, argonin, and others. 



The alcohols are but indifferent disinfectants. Koch ' in 1881 

 found that anthrax spores remained alive for as long as four months 

 when immersed in absolute and in 50 per cent ethyl alcohol. On the 

 other hand, while absolute alcohol possesses practically no germicidal 

 powers, possibly because of the formation of a protecting envelope by 

 the coagulation of the bacterial ectoplasm, or, as suggested above, by 

 desiccation due to the abstraction of water, dilute alcohol in a concen- 

 tration of about 50 per cent is distinctly germicidal, destroying the vege- 

 tative forms of bacteria in from ten to fifteen minutes or less.^ 

 Attention has already been called to the fact that moderate ad- 

 ditions of alcohol to aqueous solutions of mercuric chloride enhance 

 the germicidal power of this disinfectant. Additions of ethyl and 

 methyl alcohol to carbolic acid or formaldehyde solutions, on the 

 other hand, progressively decrease the bactericidal activities of these 

 substances.' 



The value of boiling alcohol for the destructionof spores — especially 

 in the sterilization of catgut — has been investigated by Saul,* who 

 found that boiling in absolute ethyl, methyl, or propyl alcohol is prac- 

 tically without effect, while spores are destroyed readily in boiling 

 dilute alcohol, the most effectual being propyl alcohol of a concentra- 

 tion of from 10-40 per cent. 



Iodoform (CHIj)^ is weakly antiseptic in itself, but when introduced 

 into wounds where active reducing processes are taking place — often 

 as the result of bacterial growth — iodine is liberated from it and active 

 bactericidal action results. 



Carbolic acid (CgHjOH), at room temperature, consists of color- 

 less crystals which become completely liquefied by the addition of 10 

 per cent of water. In contradistinction to most inorganic disinfectants, 

 the action of carbolic acid and other members of the phenol group is 



' Koch. Arb. a. d. kais. Gesundheitsamt, i, 1881. 



2 Epstein, Zeit. f. Hyg., xxiv, 1897. 



' Kronig und Paid, loc. cit. 



' Saul, Archiv f. klin. Chir., 56, 1898. 



^v. Behring, " Bekaempfung d. Infektiong-Kr^nljh.," Leipzig, 1894. 



