The article focuses on two new metals, the iridium and osmium. It highlights the work of English chemist Smithson Tennant of isolating iridium and osmium from the residue. It states that osmium is the rarest of the stable elements which is abundant in Earth's crust of about 1 gram per 200 tonnes. It indicates that osmium and iridium have long been known to be the densest of all metals but the question which is the heavier of the two is still under examination.