THE ELECTROLYTIC REDUCTION OF 

 ORGANIC SUBSTANCES 



By PERCY A. HOUSEMAN, Ph.D. (Wurz.), A.I.C. 



Organic substances capable of electrolytic reduction may be 

 divided into two classes : (i) easily reducible substances, i.e. 

 those which are reduced at any cathode ; (2) difficultly reducible 

 substances — those which are reduced only at cathodes possess- 

 ing a particularly high " super-tension," limited practically to 

 cathodes of lead and mercury. These two classes will be con- 

 sidered separately. 



The method, briefly outlined, consists in allowing the hydro- 

 gen evolved from the cathode to act upon the organic substance, 

 which is dissolved in a suitable solvent — usually sulphuric acid 

 or aqueous or alcoholic alkali. The substance does not need to 

 be an electrolyte, for the action is a purely chemical reduction 

 by the hydrogen liberated at the cathode. Different chemical 

 agents often lead a reduction in different directions, or arrest 

 the same at different phases ; and in the electrolytic process this 

 finds a parallel in the regulation of the course of the reduction 

 by variations in the cathode material — current strength, and, in 

 the case of easil}'' reducible substances, more particularly by the 

 potential,^ which regulates the pressure under which the ions 

 are discharged from the solution, i.e. the energy with which the 

 liberated hydrogen is capable of reacting. A higher potential 

 corresponds in action to the use of a stronger chemical reducing 

 agent. 



In a similar way, choice of the size of the electrodes gives 

 the power of regulating the concentration of the discharged 

 ions, i.e. the number of ions liberated per unit of cathode 

 surface, this factor also influencing the course of electrol3tic 

 reductions. 



The earlier work was done on easily reducible substances by 



* Haber, Zeitschr. f. Elcctroc. 4 (1898), 506 ; ZeiiscJir.f.phys. CJiem. 32 (1900), 

 193- 



589 38 



