Abstract
This report deals with the studies on settle gelatine drop method to evaluate the preventability of soft film type rust preventive oils. This evaluation method is recognized to be more useful than the ordinary settle water drop method studied by Baker et al., because of its better procedure and statistical consideration in analyses of test results. The test specimen is a plate having 75mm×55mm×3mm in its magnitude, and 20 drops of each 0.05cc gelatine in which potassium ferricyanide and phenolphthalein were resolved, are settled on its oil coated side. After one or two hours the green anode specks appear in drops at rondom, but if the oil is very preventive a anode specks are very few. Distribution of rust specks, appeared at rondom in each drops, follows Pólya-Eggenberger's distribution, and the rust drop numbers in 20 drops follows a distribution as attribute values. These values are used in each factorial experiments by the adequate transformations of the attributes, and known useful as numeration of rust preventability of test oils.
