272 



C.-E. A. WiNSLOW AND E. E. LOCHRIDGE 



the limits of accuracy of the experiment, produced respectively the 

 99 per cent and the 100 per cent reduction in the two acids. 



TABLE 3. 

 Action of Hydrochloric Acid on B. typhi in Tap Water. 



TABLE 4. 

 Action of Sulphuric Acid on B. typhi in Tap Water. 



Tables 3 and 4 show that the typhoid bacillus is considerably 

 more sensitive than the colon bacillus in its reaction to an excess of 

 acid. The 99 per cent reduction was reached with hydrochloric 

 acid at a strength of 0.0030 normal and 2.94 parts of dissociated 

 hydrogen, and the 100 per cent reduction with 0.0050 normality and 

 4.85 parts of dissociated hydrogen. With sulphuric acid the 99 per 

 cent reduction was reached with 0.0028 normality and 2.54 parts of 

 hydrogen, and the 100 per cent reduction with 0.0045 normality 

 and 3.90 parts of hydrogen. The fact that the 0.0038 normal solution 

 of sulphuric acid showed only 96 per cent reduction is one of the 

 abnormalities which unfortunately sometimes occur in bacteriological 

 work. In general, the results show again that the two acids exert 

 the same quantitative effect, although in this case, the solution being 

 weaker and the dissociation of the two acids more nearly the same, 

 the difference between normal strength and concentration of dis- 

 sociated hydrogen is not clearly shown. 



