. The Street railway journal . atter of electrolytic corrosion of water pipes,gas pipes and other buried conductors is serious in verymany electric railway systems, so serious that it is worthdetailed study as one of the gravest factors bearing on thedesign of the return circuit. One would naturally supposethat the actual amount of damage done by the compara-tively .small currents distributed over a large space, wouldbe rather slight. vSo it would be if it were intermittent,but when the electroljtic process goes steadih on ^\eekafter week and month after month, the aggregate result issomewhat
. The Street railway journal . atter of electrolytic corrosion of water pipes,gas pipes and other buried conductors is serious in verymany electric railway systems, so serious that it is worthdetailed study as one of the gravest factors bearing on thedesign of the return circuit. One would naturally supposethat the actual amount of damage done by the compara-tively .small currents distributed over a large space, wouldbe rather slight. vSo it would be if it were intermittent,but when the electroljtic process goes steadih on ^\eekafter week and month after month, the aggregate result issomewhat formidable. One ampere flowing steadily froman iron surface will eat away very nearly twenty pounds ofmetal per 3ear. So, in the case of conduction to a pipejust investigated, the resulting corrosion would amount tohalf a tvn per year. This destruction would be done in thesurfaces of exit from the pipe and if the conditions weresuch as to limit these surfaces to a comparatively smallarea the local damage would be very FIG. 27. to cables, bv:t over the main area of the city it was fromcables to track, giving a large area in which corrosionmight be expected. Differences of potential as high asfive volts were obser\^ed, while experiments in other citieshave shown as much as twenty-five volts. It is interest-ing to note that one of the first experiments tiied to re-lieve this electrolytic action was to sink in the earthground plates connected to the cables in the hope thatthe current flow would take place mainly through potential differences even at points quite near theseplates were quite unchanged, showing very plainly theintense badness of the earth as a conductor, which hasalready been pointed out. The method of treatment which proved most effective
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
