EFFECT OF ACIDS ON TYPHOID AND COLON BACILLI 265 



normal sodium formate showed active fermentation, as did a solution 

 of 0.0166 normal hydrochloric acid and 0.2 normal sodium chloride. 

 The same phenomenon was observed with oxalates, nitrates, sulphates, 

 and acetates. An exhaustive study in the case of hydrochloric acid 

 showed that, while a certain amount of sodium chloride diminished 

 the toxicity of the acid, a much larger amount actually increased it. 

 Bial attributes this to a catalytic action of chlorine ions, but it seems 

 to us that the facts may be explained more simply by the direct 

 inhibiting effect of the sodium chloride and its ions. Bial found that 

 twice normal sodium chloride without any acid prevented fermenta- 

 tion; and it is quite possible, in dealing with living organisms, that 

 the combined effect of the acid and the chloride would be inhibitory 

 at concentrations which with either acid or base alone might allow 

 fermentation to go on. Bial studied also the effect of hydrochloric 

 acid and sodium chloride in the presence of peptone, and found that 

 the yeast would bear more of the salt than in the presence of acid 

 alone. 



The experiments of Paul and Kronig demonstrated clearly that 

 in certain solutions disinfectant action runs parallel with the presence 

 of dissociated ions. The work upon the higher plants and the mold 

 fungi confirmed these results, but showed that in other cases the 

 undissociated molecule is of great importance. Bial's studies brought 

 out clearly the influence of neutral bodies, inorganic salts or proteids, 

 in diminishing disinfectant action by decreasing dissociation. 



The problem is, of course, complicated by still other chemical 

 interactions which are more obscure. For example, Scheurlen, (1895), 

 Beckmann (1896), Romer (1898), and Spiro and Bruns (1898) have 

 shown that in the case of phenol and certain other organic disinfectants 

 the addition of sodium chloride greatly increases toxic action. Still 

 another factor which affects disinfectant power has been brought 

 out in recent years by Nageli (1893), and other observers the 

 presence of suspended solid particles of neutral character. In 

 the most recent communication upon this subject by True and 

 Oglevee (1905) it was shown that the toxic effect of metallic salts 

 upon Lupinus may be entirely counteracted by the presence of 

 finely divided particles of sand, glass, filter paper, coal, starch, or 

 paraffin. On the other hand,the toxic effect of organic disinfectants 



