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527 



electrode, connected as previously described, in dilute oxalic acid, 

 the potential quickly drops to very nearly the minimum value. 

 The potential may continue to drop for some hours (this slow drop 

 amounting to 0.1-0.2 volt) if the electrode has previously been 

 subjected to an oxidizing agent; but if the electrode is previously 

 subjected to a reducing agent, a constant potential is reached 

 much more quickly. When standardized potassium permanganate 

 (in this case 0.00 1 M) 

 is added, the poten- 

 tial rises slowly until 

 the concentration of 

 positive ions becomes 

 nearly equal to that 

 of the negative ions, 

 when a trace of per- 

 manganate causes a ft7 

 jump in the poten- 

 tial. The last trace 

 of permanganate is 

 sufficient to change 

 the solution in con- 

 tact with the elec- 

 trode from a reducing 

 agent to an oxidizing 

 agent, that is, to one » W 30 to 2>*or, 



which gives up posi- fig. 2 



tive ions. It is evi- 

 dent that by this method the progress of an oxidation reactic 

 may be followed with great accuracy. 



The effect of a catalyzer in accelerating an oxidation reacti< 

 may be studied, in some cases at least, by this method with excelle: 

 results. The writer has begun some investigate 



the reaction with a view to utilizing the results in constructing a 

 theory of oxidase action. These results will be described in subse- 

 quent papers. 



s of this charactt 

 inorganic ferments" have been used to cataly 



