A greater part of corrosion of communication cable in city underground duct is caused by leakage current from the truck of electric railway. But it seemed to be that the nature and constituents in manhole water also affect for corrosion of lead sheath. Hence, aiming to obtain the relation of constituents of water corrosion and the information to corrosion control, some tests were performed in laboratory and field. Results obtained show that weight losses of test pieces were mainly affected by the lead sheath potential to earth. For the constituents of manhole water, it is known that chloride, alkali and various constituents affect for corrosion. Cathodic corrosion may be considered far less compared with anodic corrosion. As the method to prevent corrosion, cathodic protection is most effective in these cases.

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“Cis”-inhibitors (consisting of sec.-oleylamine and oleic acid) and “trans”-inhibitors (consisting of sec.-elaidylamine and elaidic acid) are examined.
The former are more effective against the corrosion of dipped mild steel than “trans”-inhibitors, when they are duly dispersed in corrosive media. But “trans”-inhibitors are more effective additives for rust-preventive oil than “cis”-inhibitors, because the metal wetted by the oil containing “trans”-inhibitors is more repellent.

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