The name derives from the Greek hydro for "water" and genes for "forming", since it burned in air to form water. It was Henry Cavendish who collected the gas over Mercury in 1766, subjected it to systematic study, and reported his findings in 1766 to the Royal Society. He made no claim to having discovered Hydrogen. Cavendish first thought the gas was phlogiston, but then was the first to distinguish it from other gases. Probably this distinction was a major contribution to Antoine-Laurent de Lavoisier's belief that each gas is a separate element and led him to name it.
Hydrogen was observed and collected long before it was recognized as a unique gas. Robert Boyle had before 1671 dissolved iron in dilute hydrochloric acid and prepared what he described as the inflammable solution of Mars [Iron]. Johann Becher and Georg Stahl had proposed a combustible substance, phlogiston, which they felt responsible for all burning.
Hydrogen's historic use is as an industrial chemical. The heavier elements were originally made from hydrogen or from other elements that were originally made from hydrogen. Much of its current use is in improving crude oil in refineries. However, hydrogen was considered for energy even in the 19th century – by Jules Verne, as well as by contemporary scientists.
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Hydrogen is estimated to make up more than 90% of all the atoms or three quarters of the mass of the universe. This element is found in the stars, and plays an important part in powering the universe through both the proton-proton reaction and carbon-nitrogen cycle – stellar hydrogen fusion processes that release massive amounts of energy by combining hydrogen to form helium.