The International Prototype of the Kilogram (referred to by metrologists as the IPK or Le Grand K; sometimes called the ur-kilogram, [1] [2] or urkilogram, [3] particularly by German-language authors writing in English [3] [4]:30 [5]: 64 ) is an object whose mass was used to define the kilogram from 1889, when it replaced the Kilogramme des ...

May 20, 2019 · In a subterranean vault in a suburb of Paris lies a small, rarely seen metal cylinder known as Le Grand K. For 130 years, this golf-ball-sized hunk of 90% platinum and 10% iridium has served as...

Aug 29, 2018 · From 1889 to 2019, the mass of a kilogram was defined by an object known as the international prototype kilogram (IPK) or, less formally, Le Grand K. A kilogram was a kilogram because of this...

Nov 16, 2018 · Known as “Le Grand K,” the cylinder, cast in 1879, is kept carefully sequestered in a secure, controlled environment outside Paris.

Nov 13, 2018 · Le Grand K was forged in 1879 and is held in a locked vault outside Paris — revered and kept under lock and key because its mass, a little over 2 pounds, is the official definition of the...

May 20, 2019 · More than a century of cleanings and exposure to air had caused the original French prototype — known as the International Prototype of the Kilogram, or “Le Grand K” — to lose about 50...

Nov 16, 2018 · Since 1889, Le Grand K, a sleek cylinder of platinum-iridium metal, has ruled from its underground vault in Paris. An absolute monarch, it was the very definition of one kilogram of mass.

Jun 27, 2016 · The egg-size alloy of platinum and iridium, known as "Le Grand K," has sat inside a hermetically sealed room in Paris since 1879. Le Grand K serves as the benchmark against which all...

May 22, 2014 · Hidden in a vault outside Paris, vacuum-sealed under three bell jars, sits a palm-sized metal cylinder known as the International Prototype Kilogram, or “Le Grand K.” Forged in 1879 from an alloy...

Nov 16, 2018 · Forged in 1879 and sanctioned by the General Conference on Weights and Measures at its first meeting, Le Grand K, the international prototype of the kilogram, has been kept under lock and key...