Adeus ao quilo; aposentaram o cilindro de platino-irídio

What’s a Kilogram? The Hunk of Metal That Defined It for 130 Years Has Been Retired

The closely guarded cylinder of platinum-iridium, kept under strict control in France, has outlived its usefulness

Jo Craven McGinty

The Wall Street Journal,  June 7, 2019 11:14 a.m. ET

Once upon a time, a kilogram was defined by a hunk of metal stored beneath a trio of bell jars in a climate-controlled vault in the basement of the International Bureau of Weights and Measures in France.

The closely guarded cylinder of platinum-iridium was forged in 1889.