Abstract
The authors studied the cathodic protection of mild steel and gun metal in acid river water. The protection by the use of zinc was almost ineffective and the protectjon with external E.M.F. required very large protective current density. The effective distance of zinc protector was determined by measuring electrical conductivity and current density in corrosion cell, On the other hand, Laplace’s equation for voltaic couple was solved approximately in the simplest case. The solution was in qualitatively good coincident with the experimental results.
