Corrosion rates of three alloys of aluminium (28, 3S and M57S) and the inhibitive efficiency of agar-agar, dextrin and gelatin at three concentrations have been determined in 0·3 M NaOH solution at 22°, 40° and 60°c. The corrosion rate increases with increase in the quantity of impurities in the alloys, with the period of immersion and with temperature. Agar-agar is a more efficient inhibitor than are dextrin or gelatin at temperatures up to 40°c. None of the inhibitors could give satisfactory protection of alloy M57S, nor of any of the three alloys at 60°c. The adsorption characteristics of the inhibitors follow Temkin's isotherm.
