First anesthesia: Dec. 11, 1844

After taking a deep breath of nitrous oxide—aka laughing gas—Horace Wells, a respected dentist in Hartford, Connecticut, has his assistant yank a wisdom tooth out of his mouth.  It doesn't come out easily, but Wells feels no pain.  After the gas wears off, Wells declares that they have witnessed the beginning of "a new era in tooth-pulling."

Wells had come up with the idea of using laughing gas as anesthesia only the night before, after attending a nitrous oxide demo at a local theater.  At the time, such exhibitions weren't that unusual; the "shows" were built around the onstage antics of audience members who had volunteered to inhale the gas.

That night, one man under the influence of the gas ran into a settee onstage and badly cut his knee. Yet he seemed to feel no pain. Afterwards, Wells asked the man running the exhibition to bring nitrous oxide to his office the next morning. As he had suspected, the gas kept him pain-free while his wisdom tooth was extracted.

Wells immediately began using nitrous oxide in his practice and encouraged other local dentists to do likewise. Then he boldly arranged to do a demonstration for doctors at Massachusetts General Hospital a month later. It didn't go well.

A medical student in the audience volunteered to have an aching tooth removed after inhaling nitrous oxide.  But when he cried out during the procedure, the doctors and students watching began heckling Wells.  The volunteer would later say that he hadn't really felt pain and had likely responded instinctively to someone pulling his tooth.

But Wells was humiliated by the experience and returned dejectedly to Hartford. Soon thereafter, he developed a serious illness and gave up his dental practice, although he continued to be an advocate for using nitrous oxide.

To make matters worse, later that year a former partner of Wells' named William Morton demonstrated the use of ether as an anesthetic before an audience at Massachusetts General—where Wells had suffered such embarrassment. Not only were the doctors impressed, but Morton went on to claim that he had discovered anesthesia.

Wells spent much of the next few years engaged in what his wife would refer to as "the gas wars,"  even traveling to Europe to meet with scientific societies and academies to make the case that the use of anesthesia for surgery had been his discovery.

By 1848, he had moved to New York and began to experiment with  chloroform as an anesthetic.  He became addicted to the gas and began behaving erratically, at one point tossing sulfuric acid at two prostitutes outside his office.

He was arrested, but managed to take chloroform and a razor into his jail cell.  It was there, at the age of 33, that Wells slashed his femoral artery and died.

The Parisian Medical  Society had voted to acknowledge Wells as the person who had pioneered the use of gas as anesthesia, but he died before his heard the news.

Sixteen years after his death, the American Dental Association officially recognized Wells as the discoverer of anesthesia. Six years later, in 1870, the American Medical Society followed suit.