English chemist and physicist · 1832–1919
William Crookes
William Crookes discovered thallium in 1861 from a single bright green line in a spectrum.
How Thallium was found
Crookes was examining residues from a sulfuric acid factory for tellurium when he saw a green line in their spectrum that no known element produced. He named the new element thallium, from the Greek thallos, a green shoot.
He isolated the metal the next year. The French chemist Claude-Auguste Lamy produced it independently at about the same time, and the two disputed priority.
Life and career
Born 1832 · Died 1919
Crookes was born in London, one of 16 children of a tailor, and studied at the Royal College of Chemistry. He ran his own laboratory and edited the journal Chemical News for decades.
His experiments with vacuum tubes, now called Crookes tubes, led others to the discovery of X-rays and the electron. He invented the radiometer, the little vane that spins in sunlight, and was knighted in 1897. He also investigated spiritualist mediums, which damaged his reputation.
Also known for
- The Crookes tube
- The Crookes radiometer
- President of the Royal Society, 1913–1915
Discovered in the same era
Other elements identified within ten years of 1861.