Ruthenium, one of the platinum group of metals, closely allied to osmium in many of its chemical relations. It was first observed by Prof. Osann in ores from the Ural mountains, and was named by him from Ruthenia (for Russia). It was afterward fully described by Prof. Claus, to whom the credit of the discovery is usually ascribed. The platinum ores of Russia, America, and Borneo contain it, and it has been detected by Wöhler in combination with osmium and sulphur in the mineral laurite found in Oregon and Borneo. To prepare ruthenium, Deville employs iridosmine, a refuse alloy from gold pen manufactories and assay offices: This alloy is fused with four or five times its weight of zinc in a carbon crucible; the heat is then raised sufficiently to volatilize all of the zinc, and the resulting mass is again fused with three parts of barium binoxide and one part of saltpetre; the crucible is broken up, and its contents are treated with nitric and sulphuric acids. The oxide of ruthenium thus obtained is fused in a lime or magnesia crucible by means of the oxyhydrogen blowpipe. After osmium it is the most infusible of all metals, and it is only possible to melt small quantities in the hottest portion of the oxyhydrogen flame, at a temperature that would convert gold and platinum into vapor.

The specific gravity of the fused metal is 11.4. Its symbol is Ru. It can be alloyed with other metals, such as zinc and tin, but is of no particular value as an alloy. Schönbein discovered that ruthenium in the form of sponge would decompose water in the presence of chlorine. If some of the sponge be projected into chlorine water, oxygen gas is at once liberated and hydrochloric acid formed; the metal is not at all affected, and if chlorine were to be slowly conducted into the water, the liberation of the oxygen could be made continuous.