English chemist · 1761–1815
Smithson Tennant
Smithson Tennant discovered osmium and iridium in 1803, the two densest elements known. Earlier, he proved that diamond is nothing but carbon by burning one.
- Elements credited
- 2
- Discoveries
- 1803
- Co-discoverers
- 0
- Where
- England
The work
Working with William Hyde Wollaston on South American platinum ore, Tennant took the black powder that would not dissolve in aqua regia. Others had thought it was graphite. He showed it contained two new metals.
He named one iridium, after Iris, the Greek goddess of the rainbow, because its salts came in so many colours. The other gave off a strong smell when heated, from volatile osmium tetroxide, so he named it osmium, from the Greek osme, “smell”.
Osmium and Iridium side by side
Life and career
Tennant was born in Selby, Yorkshire, and studied medicine in Edinburgh and Cambridge, but became a gentleman chemist and farmer. In 1796 he burned diamond and charcoal and showed that equal weights produced the same amount of carbon dioxide, proving both are pure carbon.
He became professor of chemistry at Cambridge in 1813, but died two years later when a bridge collapsed under his horse near Boulogne, in France.
Also known for
- Proved that diamond is a form of carbon