The discovery of oxygen, the gas that sustains life and fuels combustion, is not attributed to a single person but rather to a complex series of experiments conducted by three scientists in the 1770s. The answer to who “found” oxygen depends on the definition: the first physical isolation, the first public announcement, or the first correct identification and naming of the element. This multi-layered account reveals a fascinating period in scientific history where independent work, delayed publication, and conceptual breakthroughs converged.
The Initial Isolators: Scheele and Priestley
Swedish pharmacist Carl Wilhelm Scheele was the first scientist to successfully isolate oxygen, conducting his experiments around 1772. Scheele employed several methods, including heating compounds like mercuric oxide, which released the gas. He noted that the gas was odorless, colorless, and supported combustion with remarkable intensity. Scheele called his discovery “fire air” (Feuerluft). His work was delayed in publication until 1777.
English clergyman Joseph Priestley independently isolated the same gas on August 1, 1774. He focused intense sunlight onto red mercuric oxide, releasing a gas that caused a glowing splinter to burst into flame. He also famously found that a mouse could survive longer in this gas than in ordinary air.
Priestley, a proponent of the then-dominant phlogiston theory, called his discovery “dephlogisticated air.” He believed it was common air stripped of all its phlogiston, making it especially pure. He announced his findings publicly and published them quickly, giving him priority of announcement.
Naming the Element: Lavoisier’s Conceptual Breakthrough
French chemist Antoine Lavoisier received news of the gas from Priestley in October 1774. Lavoisier, a meticulous and quantitative experimenter, recognized that the gas was not merely a purer form of air, but a distinct chemical substance. He systematically investigated its role in chemical reactions, particularly combustion and respiration. Lavoisier demonstrated that air was composed of two parts: one part that supported life and combustion, and another, inert part (later named nitrogen).
Lavoisier’s research fundamentally challenged the phlogiston theory, which proposed that a mysterious substance was released during burning. He proved that combustion was the chemical combination of the burning substance with the newly discovered gas, not the release of phlogiston. This realization formed the foundation of modern chemistry. In 1778, Lavoisier coined the name “oxygène,” deriving it from Greek words meaning “acid-former.”
Resolving the Credit: The Historical Timeline and Recognition
The question of who “found” oxygen remains complicated due to the staggered timeline of isolation, announcement, and interpretation. Scheele was the first to successfully isolate the gas in 1772, but his work was not published until 1777. Priestley isolated the gas second, in 1774, but was the first to publicly announce his discovery. Priestley, however, misinterpreted his finding through the lens of the outdated phlogiston theory.
Lavoisier, building upon the isolated gas provided by Scheele and Priestley, was the first to correctly identify it as an element, discard the phlogiston concept, and give the gas its lasting name, oxygen. While Scheele has priority of isolation and Priestley has priority of public announcement, Lavoisier is credited with the true conceptual breakthrough. The lasting recognition belongs to all three men.