Ruthenium - 44Ru: historical information
Ruthenium was isolated in 1844 by Karl Karlovich Klaus, who obtained ruthenium from the part of crude platinum that is insoluble in aqua regia. It is possible that a Polish chemist Jedrzej Sniadecki had in fact isolated ruthenium from some platinum ores rather earlier than this in 1807 but his work was not ratified, apparently as he withdrew his claims. He called it vestium.