Effect of Acids on Typhoid and Colon B.xcilij 



TABLE 13, 

 Disinfectant Action of Sulphuric Acid on b. typhi in i per Cent Peptone Solution. 



TABLE 14. 

 Comparative Toxicity of Mineral Acids in Distilled Water and i per Cent Peptone Souttion. 



(Parts per 1,000,000 of dissociated hydrogen.) 



It is evident that in some way the peptone exerts a strong inlluencc 

 in counteracting the toxic effect of the acids. It at first occurred to 

 us that this might be due simply to the fact that peptone solution 

 furni.shed a more favorable medium for the bacteria, and thus enabled 

 them to resist unfavorable conditions. Such an effect would, how- 

 ever, hardly be expected in so short a period as 40 minutes; and this 

 explanation fails to account for the fact that the toxicity of the hydro- 

 chloric acid is much more diminished than that of the sulphuric acid. 

 Reference to Tables 15-17, which show the results obtained with the 

 organic acids, makes it still clearer that a specific chemical action is 

 involved. 



Evidently with the organic acids disinfectant power is much 

 less affected by the presence of peptone. With B. coli acetic acid 

 produces a 100 per cent reduction when in a strength of 0.0935 



