Barnacle electrode

The Barnacle Electrode Technique for Determination of Diffusible Hydrogen Concentration... 

Castle found that a cathode made from a steel plate could be prevented from fouling in seawater when a current density in excess of 1 mAcrn was used. He also found that the cathodic products of electrolysis in solution within short distances from the electrode was unfavorable for fouling organisms however, the existence of a continuous electric field did not keep the free-swimming larvae of fouling organisms away from electrodes immersed in the sea, and the attached foulers like barnacles tolerated a current density of 1 A cm for 15 min. 

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