How Nitrous Oxide Works

Seventy years before Horace Wells began experimenting with nitrous oxide as a dental anesthetic, an Englishman named Joseph Priestly was on the verge of a series of momentous discoveries that would forever change our understanding of chemistry.

Priestly was one of the great Enlightenment thinkers, a contemporary of Benjamin Franklin and a prolific writer on every imaginable subject, from politics to religion to the nature of electricity [source: Chemical Heritage Foundation].

In the 1770s, Priestly turned his attention to the study of "airs," as gases were called in the 18th century. Living next to a brewery, Priestly had access to a nearly unlimited supply of carbon dioxide bubbling from the fermentation tanks. He adopted techniques used by Stephen Hales, who invented a device called a pneumatic trough to collect and isolate gases respired by plant leaves [source: Encyclopaedia Britannica].

With his own pneumatic trough, Priestly was able to isolate and identify eight gases — a research record that stands today — including oxygen (O2), nitrogen (N2), hydrogen chloride (HCI), sulfur dioxide (SO2) and nitrous oxide (N2O), or what Priestly called "nitrous air, diminished" [source: Zuck et al.].

It was another English chemist, Humphry Davy, who would shed further light on the mysterious properties of nitrous oxide. As laboratory superintendent of the Pneumatic Institute, Davy investigated the use of different gasses as curative therapies [source: Zuck et al].

In those days, self-experimentation was perfectly normal, and Davy thought nothing of huffing random gasses — including toxic fumes like carbon monoxide and carbonic acid — in search of scientific evidence [source: Watt].

In 1800, a presumably lightheaded Davy published a thick tome on nitrous oxide, but only made passing mentioned of its anesthetic properties, writing, "As nitrous oxide appears capable of destroying physical pain, it may probably be used with advantage during surgical operations in which no great effusion of blood takes place" [source: Zuck et al.].

It would be another 40 years before nitrous oxide was rediscovered by Wells and eventually accepted as a wonder drug for surgery.