Electrolytic corrosion of iron by direct current in street soil

The electrolytic corrosion of iron when exposed to an electric current leaving the iron in damp soil has already received a great deal of attention and is a matter of very great practical importance. Stray currents from direct-current electric railway systems employing the running tracks as return conductors frequently reach underground piping systems and cause corrosion by electrolysis. There has been some question as to whether or not the weight of iron oxidized or destroyed under the conditions existing on underground structures is equal to that calculated from Faraday´s law, on the basis of 1.044 grams of iron destroyed by one ampere-hour, and whether various kinds of iron are corroded to the same extent with the same amount of current leaving the iron to pass to damp soil; and certain classes of iron have been claimed to resist electrolytic corrosion. Some have also believed that with very low current densities the amount of corrosion produced is less than the theoretical amount.