Henry Cavendish (/ˈkævəndɪʃ/ KAV-ən-dish; 10 October 1731 – 24 February 1810) was an English experimental and theoretical chemistand physicist. He is noted for his discovery of hydrogen, which he termed "inflammable air".^[1]He described the density of inflammable air, which formed water on combustion, in a 1766 paper, On Factitious Airs. Antoine Lavoisier later reproduced Cavendish's experiment and gave the element its name.

Cavendish, known for his reclusive personality, conducted research notable for its accuracy and precision. His work included researches on the composition of atmospheric air, the properties of different gases, the synthesis of water, the law governing electrical attraction and repulsion, a mechanical theory of heat, and calculations of the density (and hence the mass) of the Earth. The experiment he devised to measure Earth's density, which also informs calculation of the gravitational constant, is now known as the Cavendish experiment.

Cavendish found that a definite, peculiar, and highly inflammable gas, which he referred to as "Inflammable Air", was produced by the action of certain acids on certain metals. This gas was hydrogen, which Cavendish correctly guessed was proportioned two to one in water.^[6]

Brillant!!! Sad he lost his mum to childbirth.