The accurate and rapid determination of the true capacity of shallow jars of small volume commonly used as containers for certain cosmetic and pharmaceutical products is not so simple as may first appear. In contrast to volumetric flasks or specific gravity bottles, the orifice of such containers is great as compared to their volumetric capacity, and thus errors due to meniscus effects are greatly exaggerated when standard calibrating liquids such as water or mercury are used. This article describes experiments to fill shallow jars precisely.