Nitrous oxide was discovered in 1772, but for decades the gas was considered no more than a party toy. People knew that inhaling a little of it would make you laugh (hence the name “laughing gas”), and that inhaling a little more of it would knock you unconscious.
In 1844, Horace Wells, a dentist in Connecticut, had an idea after witnessing a nitrous mishap at a party. A friend of Wells took some gas and fell and suffered a deep gash in his leg, but he didn’t feel a thing.
To test his theory, Wells arranged an experiment with himself as the guinea pig. He knocked himself out by inhaling a large does of nitrous oxide, and then had a dentist extract a bad tooth from his mouth. When Wells came to, his tooth had been successfully pulled.
After further experiments, Wells was jailed while high on chloroform and he committed suicide. In 1864 the American Dental Association formally recognized him for his discovery.