English chemist and inventor · 1778–1829
Humphry Davy
Humphry Davy was the first person to use electricity to pull elements out of their compounds. In just two years he isolated sodium, potassium, calcium, boron and several other metals, and became the most famous scientist in Britain.
- Elements credited
- 4
- Discoveries
- 1807–1808
- Co-discoverers
- 2
- Where
- France and England; England
Discovery timeline
1807 · England
Sodium is a soft, silvery alkali metal that reacts violently with water. In compounds like table salt it is essential to all animal life.
1807 · England
Potassium is a soft alkali metal that reacts violently with water, burning with a lilac flame. It is vital for nerve and muscle function.
1808 · France and England
Boron is a hard, black metalloid that is rare in the universe but concentrated in Earth’s crust in borate minerals.
1808 · England
Calcium is a reactive alkaline earth metal and the most abundant metal in the human body, where it builds bones and teeth.
The discoveries
In 1807 Davy passed current from a huge voltaic battery through molten potash at the Royal Institution in London. Small globules of metal formed at the negative wire, burst into flame and skittered across the surface. His assistant recorded that Davy danced around the room with delight. It was potassium. Days later he repeated the trick with soda and obtained sodium.
In 1808 he turned to the alkaline earths. Working with mercury electrodes to collect the metals as amalgams, he isolated calcium, along with barium, strontium and magnesium. The same year he also obtained boron from boric acid, a few days after Gay-Lussac and Thénard reported it in Paris.
The experiments settled a long debate. Potash, soda and lime had been suspected to contain unknown metals, but no chemical reaction was strong enough to release them. Electricity was.
Life and career
Davy was born in Penzance, Cornwall, and was apprenticed to a surgeon-apothecary. In his teens he began experimenting on his own, and at 20 joined the Pneumatic Institution in Bristol, where he studied the effects of breathing nitrous oxide and noted that it could ease pain in surgery.
In 1801 he moved to the Royal Institution, where his public lectures drew packed crowds. In 1815 he invented the miner’s safety lamp, which used a wire gauze to stop flames igniting firedamp, and declined to patent it. He became President of the Royal Society in 1820 and died in Geneva at 50.
Also known for
- The Davy safety lamp for coal miners
- Showed that chlorine is an element, not a compound
- Hired the young Michael Faraday as his assistant
Legacy
Davy’s method, electrolysis, is still how sodium, potassium, calcium and magnesium are made today. His greatest discovery, he was sometimes said to have joked, was Michael Faraday.