Michael Sendivogius (; ; 2 February 1566 – 1636) was a Polish alchemist, philosopher, and medical doctor. He is famous as being the first to purify certain compounds and create certain acids. He was also the first to work out that a certain gas was given off when heating potassium nitrate. This gas was oxygen, and he was the first to identify it. He also worked out that this gas was in air, and called it the "food of life".