Oxygen is a fundamental element, making up about one-fifth of the Earth’s atmosphere, necessary for respiration and combustion. Determining which country discovered oxygen is complex because the gas was independently isolated by multiple scientists in different nations around the same time. The first to isolate the element, the first to publish the discovery, and the first to correctly define its chemical nature were separate events. This historical complexity means three different countries lay claim to a significant part of the discovery narrative.
The Initial Isolation in Sweden
The initial successful isolation of the gas occurred in Sweden through the work of the Swedish-German chemist Carl Wilhelm Scheele. Working in Uppsala, Scheele produced the gas as early as 1771 or 1772, years before his contemporaries. He achieved this by heating various compounds, including mercuric oxide and nitrates, which released the unknown substance.
Scheele named the gas “fire air” (Feuerluft), observing its ability to support combustion. He noted that materials burned much more vigorously in this air than in normal atmospheric air. Despite completing his experiments first, Scheele’s findings were not published immediately due to delays from his publisher. His detailed account, Chemical Treatise on Air and Fire, did not appear until 1777.
The Publicized Discovery in England
The credit for the first public announcement of the gas went to the English clergyman and natural philosopher Joseph Priestley. Priestley performed his experiment on August 1, 1774, in Wiltshire, England. He used a large glass lens to focus sunlight onto red mercuric oxide, which released a colorless gas.
Priestley found that a candle placed in the collected gas burned vigorously, and a mouse placed inside remained active for a prolonged period. He promptly published his results in 1775, securing his place as the discoverer in the eyes of the scientific community. Adhering to the phlogiston theory, Priestley called the new substance “dephlogisticated air.” He believed it was common air stripped of phlogiston, allowing it to absorb more of the hypothetical fire element released during combustion.
Defining the Element and Its Name
The final chapter of the discovery took place in France, led by the chemist Antoine Lavoisier. Although Lavoisier did not isolate the gas independently, he received information from Priestley, who visited him in Paris in October 1774 and described his experiment. Lavoisier then conducted his own quantitative experiments, which allowed him to determine the gas’s true nature.
Lavoisier was the first to realize that the gas was not merely a purer form of air but a unique chemical element. His work correctly explained the role of the gas in both combustion and respiration, leading him to dismantle the outdated phlogiston theory. In 1778, Lavoisier coined the modern name for the element, oxygène, derived from Greek words meaning “acid-former.” This definition and naming finalized the identification of oxygen as a distinct substance and ushered in the modern era of chemistry.