EFFECT OF ACIDS ON TYPHOID AND COLON BACILLI 271 



TABLE i. 

 ACTION OF HYDROCHLORIC Aero ON B. coli IN TAP WATER. 



TABLE 2. 

 ACTION OF SULPHURIC Aero ON B. coli IN TAP WATER. 



of dissociated hydrogen. With the sulphuric acid the 99 per cent 

 reduction was reached at a strength of 0.0096 normal, with 7.68 parts 

 of dissociated hydrogen, and the 100 per cent reduction at a strength 

 of 0.0166 normal, with 12.6 parts of dissociated hydrogen. These 

 results show a direct relation between disinfectant action and free 

 hydrogen ions. The normal strengths of the killing solutions do not 

 correspond very closely; 0.0077 sulphuric acid failed to do what the 

 same strength of hydrochloric acid did, and 0.0129 an d 0.0141 sul- 

 phuric acid failed to do what 0.0123 hydrochloric acid did. On the 

 other hand, when we compare dissociated hydrogen, allowing for 

 the greater ionization of the hydrochloric acid, the discrepancies 

 disappear. The same concentrations of dissociated hydrogen, within 



