Scheele discovered oxygen (although Joseph Priestley published his findings first), and identified molybdenum, tungsten, barium, nitrogen, and chlorine, among others.

[5] Scheele was born in Stralsund,[2] in western Pomerania, which at the time was a Swedish Dominion inside the Holy Roman Empire.

[2] Then, in 1757, at the age of fourteen, Carl was sent to Gothenburg as an apprentice pharmacist[5] to another family friend and apothecary, Martin Andreas Bauch.

During this time he ran experiments late into the night and read the works of Nicolas Lemery, Caspar Neumann, Johann von Löwenstern-Kunckel and Georg Ernst Stahl (the champion of the phlogiston theory).

[2] In 1765 Scheele worked under the progressive and well-informed apothecary C. M. Kjellström in Malmö, and became acquainted with Anders Jahan Retzius who was a lecturer at the University of Lund and later a professor of chemistry at Stockholm.

[2] In the fall of 1770 Scheele became director of the laboratory of the great pharmacy of Locke, at Uppsala, about 65 km (40 mi) north of Stockholm.

In 1774 Scheele was nominated by Peter Jonas Bergius to be a member of the Royal Swedish Academy of Sciences and was elected 4 February 1775.

[2] On 29 October 1777, Scheele took his seat for the first and only time at a meeting of the Academy of Sciences and on 11 November passed the examination as apothecary before the Royal Medical College, doing so with the highest honours.

After his return to Köping he devoted himself, outside of his business, to scientific researches which resulted in a long series of important papers.

In all of these experiments, he isolated the same gas: his "fire air", which he believed combined with phlogiston in materials to be released during heat-releasing reactions.

[7] Scheele achieved astonishingly prolific and important results without the expensive laboratory equipment to which his Parisian contemporary Antoine Lavoisier was accustomed.

Although Scheele was unable to grasp the significance of his discovery of the substance that Lavoisier later named oxygen, his work was essential for the abandonment of the long-held theory of phlogiston.

When he treated the pyrolusite with hydrochloric acid over a warm sand bath, a yellow-green gas with a strong odor was produced.

With that in mind, he married the widow of his predecessor,[2] Pohl, two days before he died, so that he could pass undisputed title to his pharmacy and his possessions to her.

[22] Cumulative exposure to arsenic, mercury, lead, and their compounds and, perhaps, hydrofluoric acid, which he had discovered, as well as other substances, took their toll on Scheele.

[2] Scheele's papers appeared first in the Transactions of the Swedish Academy of Sciences, and in various periodicals such as Lorenz Florenz Friedrich von Crell's Chemische Annalen.