Anticorrosive coating of steel structures has been undertaken since long, but reports on tests performed in fresh water are relatively few.
The authors have carried out long term immersion test, extending over three and half years on test steel pannels coated with over 30 kinds of commercial paints, for the purpose of selecting suitable anticorrosive paints to be used for the gate of hydroelectric station of J. N. R., at Sinano river.
The results indicated that vinyl resin paint, Cummaron resin paint, and coal tar enamel gives the good performance. Phenol resin paint was found irregular in quality according to make, and requires caution in its selection. Zinc rich paint did not perform well under the present tests.

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Corrosion inhibition efficiencies of n-dodecyl amine in which hydrogen is substituted by phenyl, o-tolyl, m-tolyl, p-tolyl, cyclohexyl or benzyl radical were determined both in a neutral saline water and in an acidic solution. Among the phenyl and tolyl substituted amines of which basic strength is equally weak, N-o-tolyl or N-p-tolyl-n-dodecylamine is a more effective inhibitor than N-phenyl- or N-m-tolyl-n-dodecylamine, because nitrogen atom of the former two amines has more mobile unshared pairs of electrons than the latter two. These data indicate that these amines are chemically adsorbed by means of coordination of the electrons to metals.
N-cyclohexyl or N-benzyl-n-dodecylamine containing more mobile lone pairs in the nitrogen atom is more chemically adsorbable in a neutral aqueous solution or in benzene solution. In a strong acid solution, however, corrosion inhibition of these amines is the less effective at low concentration, because these are capable of forming ammonium ions which are reversibly adsorbed by virtue of electrostatic attraction. Protons attract the adsorbed amine molecules from the metal surface, leaving non-protected metal. Thus, only in case of a dilute solution of inhibitor in a strong acid medium, weak base amines may be more effective than strong ones.

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