(AP) -- A kilogram just isn't what it used to be. The 118-year-old cylinder that is the international prototype for the metric mass, kept tightly under lock and key outside Paris, is mysteriously losing weight - if ever so slightly.
Content from The Associated Press expires 15 days after original publication date. For more information about The Associated Press, please visit www.ap.org .
Explore further: The science of charismatic voices