Assertion: international prototype | /r/HasProperty | ipk
Facets:
Source sentences:
text: In 1889, a cylinder of platinum-iridium, the International Prototype of the Kilogram (IPK) became the standard of the unit of mass for the metric system, and remained so until 2019.
text: : The Metre Convention is signed in 1875, leading to production of The International Prototype of the Kilogram (IPK) in 1879 and its adoption in 1889.