Joseph Priestly, an English scientist, was the first to isolate carbon monoxide and is usually given credit as its first discoverer. Earlier scientists described a similar gas or performed experiments with the gas in combination with carbon dioxide and failed to describe it.
Priestly's experiments on brewery gases led to the isolation and discovery of eight different gases in the mid to late 1700s. His last major discovery was carbon monoxide, made while he was living in Pennsylvania in the 1790s.
Arnaldus Villanovanus, or Arnold of Villanova, was a Spanish alchemist of the 13th century. He is attributed with describing a poisonous gas emitted from the burning of wood. This gas was almost certainly carbon monoxide. Unfortunately, many works and discoveries attributed to him were actually made by others and attributed to his name because of his great reputation as an alchemist.
The 17th-century scientist Jan Baptista van Helmont nearly died from experimenting with carbon monoxide without realizing what the poisonous gas was.