Wiktionary
carbogen
n. A mixture of carbon dioxide and oxygen gas.
Wikipedia
Carbogen
Carbogen, also called Meduna's Mixture after its inventor Ladislas Meduna, is a mixture of carbon dioxide and oxygen gas. Meduna's original formula was 30% CO and 70% oxygen, but the term carbogen can refer to any mixture of these two gases, from 1.5% to 50% CO.