HYDROGEN ION CONCENTRATION AND PROTEOLYSIS. 147 



recent investigation of Clark, ^ who showed the fallacies of the titrimetric 

 method. Again, the adsorption phenomenon caused bj^ the amphoteric 

 substance in the course of titration is well known, and, in the case of al- 

 bumin, is usually expressed in the following manner: — 



+ . 



In acid solution H. albumin. OH=H albumin+OH 



+ 

 In alkali solution H. albumin. OH = Albumin OPI+H 



The correctness of the above statement has been experimentall}' demon- 

 strated by Sorensen, ^ Clark ^ and others. 



In many cases the colorimetric method gives fairlj^ accurate results,* 

 but it has been noted that the presence of neutral salts as well as ampho- 

 teric substances interfere with, the determination. ^ It may, however, be 

 employed successful!}'' if it is standardized for the particular liquid.^ Lately 

 Clark and Lub" employed the principle of the colorimetric method for 

 the differentiation of the colon-serogenes family, using suitable indicators. 

 Thej' have based their experiment upon the wide divergence of the hydro- 

 gen ion concentration in a culture of one group and of the other, and dis- 

 tinguished this difference by means of paranitrophenol or methyl red. 

 The use of this method for physiologic work other than bacteriology has 

 been practiced by many. Sorensen and Palitzsch^ determined the hydro- 

 gen ion concentration of sea water. Henderson and Palmer^ used it in 

 determining the acidity of urine to diagnose normal and abnormal con- 

 ditions. In any case, the colorimetric method should be standardized 

 previous to its use, by means of the hydrogen electrode. 



Examining these methods critically in the light of physical chemistry 

 they are not satisfactory for the purpose of ascertaining the influence of 

 the So-called " true reaction " upon bacterial life. The hydrogen electrode 

 was debased to determine the hj^drogen ion concentration, and it has been 

 used* successfully in biologic fields. This method has been employed in 

 the present investigation, and its theoretical and practical discussion 

 follows. 



Theory of H Ion Concentration. — The announcement of the theory of 

 electric dissociation by Svante Arrhenius, in 1887, marked a new era in 

 physical chemistry. It was F. Kohlrausch and A. Heydweiller who demon- 

 strated that even the purest water is a conductor of electricity, and accord- 

 ingly prepared a distilled water of the least specific conductance. They 

 measured the specific conductance by means of electric conductivity, 



• Jour, of Infect. Diseases, V. 17, No. 1, July, 1915, 109. 

 > Ergebnisse d. Physiologie, Bd. 12, 423, 1912. 



' Jour, of Infect. Diseases, V. 17, No. 1, July, 1915, 109-136. 



• Miehaelis, L. Die Wasserstofiionenkonzentration, 176, 1914. 



» Miehaelis, L., and P. Rona. Biochem. Zeitschr., 23, 61, 1909. 



• Miehaelis, L. Dis Wasserstoffionenkonzentration, 176, 1914. 

 ' Jour, of Infect. Diseases, V. 17, No. 1, July, 1915, 160-173. 



» Biochem. Zeitschr., 51, 307, 1913. 



» Jour, of Biol. Chem., V. 13, No. 4, Jan.. 1913. 



