THE TOXIC EFFECT OF CERTAIN ACIDS UPON TYPHOID 



AND COLON BACILLI IN RELATION TO THE 



DEGREE OF THEIR DISSOCIATION* 



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

 (From the Biological laboratories of the Massachusetts Institute oj Technology.) 



I. INTRODUCTION. 



The researches of the physical chemists, under the leadership of 

 Arrhenius and Nernst, have shown that certain substances in aqueous 

 solution become dissociated or broken up into electrically charged 

 part -molecules (atoms or groups of atoms), which are called ions. 

 The extent to which this occurs varies with different substances and is 

 greatest in the most dilute solutions. With strong acids and bases, 

 and their salts, it is practically complete at a strength of o.ooi normal. 

 With such solutions it is evident that any effect, chemical or physio- 

 logical, which they exert, must be due to the dissociated ions. The 

 properties of a dilute solution of sodium chloride are the properties 

 of sodium and chlorine ions, and the properties of hydrochloric acid, 

 of hydrogen and chlorine ions. By the comparison of a series of 

 properly selected compounds it is easy to determine the specific 

 influence of each ion. The study of the toxic action of various 

 substances in the light of these facts promises to be of great assis- 

 tance in the development of a rational theory of disinfection. 



The first definite statement of the relation between dissociation 

 and disinfectant power with which we are familiar was made by 

 Dreser. This author (Dreser, 1893), in a study of the pharmaco- 

 logical value of various salts of mercury, found that the double 

 hyposulphite of mercury and potassium was much less poisonous 

 than other compounds containing the same amount of mercury, and 

 explained the phenomenon by the fact that this salt on dissociation 

 does not set free mercury ions, but breaks up into potassium at the 

 cathode and Hg S^O^ at the anode. His experiments were made on 

 yeast cells, frogs, and fishes. In the former case he found it possible 

 to prevent all development in a yeast culture by mercury salts, and 



♦Received for publication March 5, 1906. 



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