Michael Sendivogius (; Polish: Michał Sędziwój; 2 February 1566 – 1636) was a Polish alchemist, philosopher, and medical doctor. A pioneer of chemistry, he developed ways of purification and creation of various acids, metals and other chemical compounds. He discovered that air is not a single substance and contains a life-giving substance—later called oxygen—170 years before Scheele's discovery of the element. He correctly identified this 'food of life' with the gas (also oxygen) given off by heating nitre (saltpetre). This substance, the 'central nitre', had a central position in Sendivogius' schema of the universe. Biography Little is known of his early life: he was born in a noble family that was part of the Clan of Ostoja. His father sent him to study in university of Kraków but Sendivogius visited also most of the European countries and universities; he studied at Vienna, Altdorf, Leipzig and Cambridge. His acquaintances included John Dee and Edward Kelley. It was thanks to him that King Stephen Báthory agreed to finance their experiments. In the 1590s he was active...