CATALYSIS AND BIOCHEMICAL PROCESSES 219 



"potential," whose expression is a furtherance of the 

 change in question; and (2) by the resistance to this 

 change. The general formula C = P/R describes the 

 general conditions, where C signifies either the rate of 

 chemical change (under determined conditions of con- 

 centration, temperature, etc.) or the intensity of the 

 current flowing through the circuit, P the potential, 

 signifying a function of "chemical affinity" in the one 

 case, or the electrical pressure or "voltage" of the 

 circuit in the other, and R the resistance to either the 

 chemical change or the flow of current. In the case of 

 a chemical reaction occurring at an electrode (electroly- 

 sis), where the quantity of chemical change, e.g., of 

 copper deposited as metal at the cathode, is proportional 

 to the quantity of current flowing through the circuit 

 (Faraday's Law), the factors determining the flow of 

 current are the same as those determining the rate of 

 chemical change, and chemical resistance becomes 

 identical with electrical resistance. In such a case any 

 condition decreasing the electrical resistance or increasing 

 the electrical potential increases the velocity of the purely 

 chemical change at the electrode. 



At present it is customary to describe a catalyst as 

 a substance which in some manner, without itself under- 

 going permanent alteration, decreases the resistance 

 to the interaction of other substances in the reaction- 

 system. On such a definition any substance which 

 decreases the electrical resistance in a circuit would 

 catalyze the chemical reactions occurring at the elec- 

 trodes. Such an effect might not ordinarily be classed 

 as catalytic; but since our interest is not in defining 

 the significance to be attached to terms, but in ascertain- 



