The Minor Impurity in Spent Ores of the "Siberian Metal": Ruthenium Turns 175

The year 2019 commemorates the 175th anniversary of the discovery of the last of the platinum group metals, ruthenium. The discovery of this element is now attributed to the Russian chemist, Karl Karlovich Klaus (Carl Ernst Claus, 1796-1864). At that time, he was Professor of Chemistry at Kazan University, on the Volga River approximately 750 km (450 mi) east of Moscow. Klaus, whose laboratory practices violated practically every modern rule of laboratory safety, actually discovered the existence of the element in a crude extract of the spent platinum ores from the mint, by its odd taste and smell! Klaus and his discovery (including its defense against critics, who included Berzelius) are discussed here.