Recommendation 4 of the 82nd CIPM (1993)

Monitoring the stability of the international prototype of the kilogram

The Comité International des Poids et Mesures,


  • the results of the third periodic verification of national prototypes of the kilogram, which showed significant drifts of the national prototypes,
  • the BIPM (Bureau International des Poids et Mesures) working copies and the official copies with respect to the international prototype,
  • the fundamental impossibility of drawing definite conclusions from these results about the long-term stability of the international prototype and its copies,
  • the results of work in many national laboratories aimed at understanding the processes that lead to instability of mass standards,
  • the progress now being made in various laboratories towards independent methods of monitoring the stability of mass standards,

recommends that laboratories pursue their work on these experiments, and develop new ones, with a view to monitoring the stability of the international prototype of the kilogram and in due course opening the way to a new definition of the unit of mass based upon fundamental or atomic constants.

DOI : 10.59161/CIPM1993REC4E

The reader should note that the official version of this Resolution is the French text

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