Practical Uncertainty Limits to the Mass Determination of a Piston-Gage Weight

The mass of a 590-g piston-gage weight was determined with a standard error of 0.057 mg (0.1 ppm). The sources of er­ ror are carefully examined. These in­ clude air-buoyancy corrections, physically adsorbed surface moisture, and air-convection within the weighing chamber. We conclude that significant improvement cannot be realized with the conventional weighing techniques available to most piston-gage users.