Michal Sedziwoj, a Polish alchemist, philosopher, and medical doctor, was a pioneer in the field of chemistry. He developed methods for the purification and creation of various acids, metals, and other chemical compounds.

Sedziwoj made significant contributions to chemistry, notably discovering that air is not a single substance but contains a life-giving element, which was later identified as oxygen. He correctly identified this 'food of life' with the gas given off by heating nitre (saltpetre) 170 years before the work of Scheele and Priestley. In his schema of the universe, this substance, termed 'central nitre,' played a central role.

He also pioneered techniques for isolating and purifying various acids, metals, and other chemical compounds.

In the 1590s, Sedziwoj was active in Prague at the open-minded court of Rudolf II. Around 1600, he appeared at the court of King Sigismund III Vasa in Poland, where he quickly gained notoriety. The Polish king, an alchemy enthusiast, even conducted experiments with Sedziwoj.

At Krakow's Wawel Castle, the chamber where Sedziwoj performed his experiments remains intact. Despite his contributions, Sedziwoj faced disapproval from conservative Polish nobles who resented his encouragement of the king to spend large sums on chemical experimentation. He also worked on practical aspects such as designing mines and metal foundries.

Sedziwoj's international contacts led to his employment as a diplomat from around 1600.

Sedziwoj's most famous work, _A New Light of Alchemy_ (Latin original published in 1605), was written in alchemical language, a secret code understandable only by other alchemists. His works included a clear exposition of his theory on the 'food of life' in air (i.e., oxygen), as well as various scientific, pseudo-scientific, and philosophical theories. These works were repeatedly translated and widely read, including by notable figures such as Isaac Newton, into the 18th century.

In his later years, Sedziwoj spent more time in Bohemia and Moravia (now in the Czech Republic), where he was granted lands by the Habsburg emperor. Near the end of his life, he settled in Prague at the court of Rudolf II, gaining further fame as a designer of metal mines and foundries.

However, the Thirty Years' War (1618-48) marked the end of the golden age of alchemy. With rich patrons redirecting their funds towards war rather than chemical experimentation, Sedziwoj died in relative obscurity.