Abstract
Microscopical rust speck calculation methods to evaluate the preventability of rust preventive oils were studied.
Two methods, the ordinary method of calculating the mean rust specks of several microscopical fields of standardized magnification and a new method of calculating the specks observed only at the cross section points of inclusion lens of microscope disregarding the specks out of the cross section points, were studied and compared.
Because of the speck distribution type and the labor of counting, the former is recognized useful in the case of a few specks and the latter in the case of many specks.
