How experimentation is done: Humphry Davy and his nitrous oxide experiments

Not in the ideal dreams of wild desire
Have I beheld a rapture-waking form;
My bosom burns with no unhallowed fire:
Yet is my cheek with rosy blushes warm
Yet are my eyes with sparkling lustre filled
Yet is my mouth replete with murmuring sound
Yet are my limbs with inward transport thrilled
And clad with newborn mightiness around.

It doesn’t take a poetic genius to recognise that the poem above is pretty horrible. No sense of meter and rhythm, and generally bad verse. The poem is taken from Fullmer (2000), is entitled On Breathing Nitrous Oxide, and was written by Humphry Davy in 1799. Yes, that Humphry Davy, one of the most important chemists in the history of the science, inventor of the Davy Lamp that made miners’ work infinitely safer, one-time President of the Royal Society, brilliant populariser of science, and also mentor to Michael Faraday. If you want to know more about him, the book below is a great place to start.

The context of this poem was Davy’s appointment as a chief experimenter in the Pneumatic Institution, Bristol, where he was tasked with finding medicinal traits of various gases, including nitrous oxide, better known as laughing gas.

He started off the investigation by self-experimentation. Despite nitrous oxide being considered as toxic by its original synthesiser, Joseph Priestley, Davy devised an apparatus whereby the gas would be synthesised by heating ammonium nitrate crystals, the produced gas passed through water vapour, and the final gas getting inhaled through a wooden mouthpiece. Even if the gas weren’t toxic, Davy risked getting caught in an explosion or merely getting his lungs burned by the hot gas. Who cares.

With his assistant measuring pulse rate, Davy did the initial experiment on himself, inhaling 4 quarts, and immediately noticed the hallucinogenic properties of nitrous oxide. In fact, he needed to consult his lab notes the day after to be certain that the experiment actually took place.

He repeated the experiments on himself several times to confirm results, and sent them out for publication. These experiments were rigorous sessions with his assistant measuring all physiological variables and Davy writing down his own feelings, including that poem at the top. The poem seems superfluous until you realise this context: the poem was actually scientific data. Read it again and you will notice that what’s being described are his sensations, both physical and psychological.

Davy eventually became somewhat addicted, doing the experiments every day and expanding the scope of the analyses by even investigating the composition of the air going into and out of his lungs, both with and without the nitrous oxide (and arriving at spectacularly accurate results!).

The next step was trying to overdose himself. Having cleared his head during the day, he had his assistant administer six quarts instead of the usual four. The only difference he noted was that he lost consciousness in a similar way as to when he was inhaling carbon monoxide, a little fact that later proved to be very important: in what context would it be nice to lose consciousness? Surgery. In other words, his self-experimentation laid a foundation for the study of anaesthesia.

Around this time, he started giving nitrous oxide to willing patients and recording their physiological and psychological reactions. However, he was using a novel experimental method: he wouldn’t tell the patients whether he was giving them nitrous oxide or regular gas. In other words, he was doing blind experiments, which was rather novel.

These allowed him to establish the wide variation in reactions to the gas – some reacted well, some barely, some negatively. Some just didn’t make any sense – one recorded reaction simply said, “I felt like the sound of a harp”. And this led Davy to a new line of research, for which he asked his own friends to take the gas. And what he found from that is that the effect of nitrous oxide was highly-dependent on a person’s own psychological predispositions. A musician friend heard orchestras and choirs; Peter Mark Roget, future writer of Roget’s Thesaurus, felt inclined to write but couldn’t find words; Humphry Davy’s own poem above was a mess in terms of verse (contrary to his regular writing!), but contained perfectly valid scientific data due to his own preoccupation with experimenting at time of writing.

I retell this tale quite often, for several reasons. Those who know me know that I place a high value on self-experimentation. I do it all the time – fellow fieldworkers can attest to the number of toxic plants and animals I’ve swallowed, and fellow labworkers can attest to the number of caustic materials I’ve put on my skin and lab coat to assess their concentrations (there’s a reason why I never got into a purely lab-based subdiscipline..). I try to encourage self-experimentation by calling on its very wealthy history, such as Davy’s experiments with nitrous oxide.

It’s also a great story to illustrate how science-by-experimentation proceeds in practice. You do an experiment on yourself and notice a range of reactions. Repeat systematically multiple times, including with varied conditions, to make sure that the effects are real. Make a point of noting down everything, even what may seem useless, so you keep every avenue of research open. This is why Davy wrote a poem and told his patients to write their emotions: he recognised that the effects of nitrous oxide were both physiological and psychological. And because he kept meticulous notes, he could then investigate each of these specifically, the physiological aspects on his patients and the psychological with the friends whose psychologies he knew about.


Fullmer JZ. 2000. Young Humphry Davy: The Making of an Experimental Chemist.

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