Michal Sedziwoj (Michael Sendivogius, Sedzimir) (1566-1636) of Ostoja coat of arms 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 similar discoveries by Scheele and Priestley. 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 pos...