ANTISEPTICS 121 



the influence of various concentrations of sulfanilamide 

 on a culture of Bacterium coll in broth: 

 Concentrations Final crop 



1.0% < 5,000,000 cells per cc. 



0.75% 110,000,000 



0.50% 250,000,000 



0.25% 900,000,000 



0.10% 1,000,000,000 



The culture with 1% sulfanilamide showed no visible tur- 

 bidity, gave a slight indication of growth in the nephelo- 

 meter, and the plate count definitely proved a slight 

 multiplication in the course of 10 days, which did not 

 progress further during another w^eek of observation. 



I. TEMPERATURE AND ANTISEPSIS 



With disinfectants, an increase of temperature in- 

 creases the rate of reaction between cells and the toxic 

 compound, and thus increases the efficiency of the disin- 

 fectant. Since antiseptics react with immeasurable vel- 

 ocity, this rate cannot be influenced to a measurable de- 

 gree by temperature. However, the effect is reversible 

 and must be considered as representing an equilibrium. 

 Equilibria are affected by changes in temperature, and 

 equilibria of instantaneous ionic reactions are as de- 

 pendent upon temperature as those of slow organic re- 

 actions. 



The equilibrium constants of exothermic and endo- 

 thermic reactions are affected in opposite ways by a 

 change of temperature. The precise nature of the reac- 

 tion which interferes with multiplication when the anti- 

 septic is added to a culture is not known. It may be 

 endothermic with one antiseptic and exothermic with an- 

 other. It is therefore impossible to predict in a general 

 way the effect of temperature on all antiseptics. 



