The purpose of this standard is to indicate a method for determining the ashes that result from burning, under the conditions described, drying oils, both natural and synthetic, and their fatty acids. This method is not applicable to fired oils, because lead driers are partially reduced by carbon to give metallic lead and oxides of variable composition, while zinc oxide is relatively volatile at the temperature of the furnace. muffle, so the results obtained in cooked oils are empirical and not very reproducible.