No one knows why — though it’s probably not due to someone shaving off a piece — but the International Prototype Kilogram really does seem to have lost about 50 micrograms over time: http://www.sciencedaily.com/releases/2007/09/070921110735.htm
No one knows why — though it’s probably not due to someone shaving off a piece — but the International Prototype Kilogram really does seem to have lost about 50 micrograms over time: http://www.sciencedaily.com/releases/2007/09/070921110735.htm