"Fixed air" or carbon dioxide was discovered by Flemish physician and chemist K.J.B. von Helmont (1599-1644), the first scientist to distinguish individual gases from air. But carbon dioxide was first isolated by Scottish chemist Joseph Black in 1757. Black was Professor of Chemistry at Glasgow University and a Professor of Medicine at Edinburgh University. As well as isolating carbon dioxide, Black propounded the theories of latent and specific heat. This was later applied by James Watt to the steam engine with momentous consequences.
A little carbon dioxide is often added to the gases used in anaesthesia. This is because its presence in the blood stimulates breathing.