394 COLLOIDS IN BIOLOGY AND MEDICINE 



* *. 



matter of fact but few disinfectants are furnished by the inorganic 

 acids and bases and by the salts of the baser metals. Of course we 

 do not include such concentrations of the acids and bases as produce 

 a direct destruction of the organized substance. As a matter of fact, 

 substances containing the phenyl group are our most useful dis- 

 infectants, such as carbolic acid, cresol, naphthol, anilin water, etc. 

 H. BECHHOLD and P. EHRLICH* by combining phenyl groups 

 (derivatives of dioxydiphenylmethan and o-diphenol) obtained sub- 

 stances of hitherto unequalled disinfectant action (with the exception 

 of sublimate, etc.) and even this action was greatly increased by /the 

 introduction of halogens. The work of H. BECHHOLD, * 9 which 

 introduced into practice the halogen derivatives of naphthol and 

 dicresol, disinfectants of great activity, establishes the breadth of 

 this assumption. 



A dilute solution of alkalis or acids is the normal environment 

 for the majority of microorganisms. Although the majority of micro- 

 organisms prefer a more alkaline nutriment corresponding to the 

 dearth of H ions in the animal organism, there are other bacteria and 

 moulds, for instance, lactic acid bacteria, which require or prefer 

 an acid medium, e.g., the moulds which grow on acid fruit. From 

 this it follows that when acids or alkalis injuriously affect a micro- 

 organism, the specific vital conditions of the microorganism in ques- 

 tion have been unfavorably disturbed and accordingly it is impos- 

 sible to speak of a general injurious action of H or OH ions. 



Many salts of the heavy metals (e.g., silver, mercury and copper 

 salts) are disinfectants. Their strong adsorptive power, in which 

 sublimate excels all others, was demonstrated by P. MORAWITZ.* 



Adsorptive capacity is only a condition preliminary to the exercise 

 of specific toxic action. It is generally accepted in the case of salts 

 of the heavy metals that this toxic action depends on the forma- 

 tion of albuminates. I am at present engaged in the explanation of 

 these phenomena and I am already in a position to state that adsorp- 

 tion is by no means the most important factor. 



Finally, there are among the inorganic salts, substances with 

 specific activity, e.g., the fluorids, thallium carbonate, sulphurous 

 acid salts, boric acid, etc. We know of no disinfectants among the 

 sugars or their related substances (e.g., glycerin). P. EHRLICH and 

 H. BECHHOLD * as well as H. BECHHOLD * 9 have shown in the case of a 

 large number of aromatic compounds that the introduction of sulpho 

 groups into a disinfectant considerably diminishes its activity. 



Adsorption in water according to H. FREUNDLICH * l is favorably influ- 

 enced by the phenyl group and the halogens. This author mentions 

 as an example chlorbenzoic acid (X = 154), benzoic acid (X = 140). 



