In January 2012, an attractive woman over 40 and that guy from That '70s Show were going through a rough patch (spoiler alert: it didn't work out). Demi Moore, the woman in question, allegedly turned to the comfort of nitrous oxide, also called "whip-its," "whippits," "whippets," "nossies," "hippy crack," and, of course, "laughing gas."

Moore's experience with nitrous oxide was not, however, the brief, weightless euphoria that most people report: She collapsed with seizure-like symptoms and was rushed to the hospital. Her subsequent stint in rehab – for eating disorder issues and substance abuse – could have sparked a nationwide soul-searching about nitrous oxide and other inhalants abuse; it mostly just sparked a bunch of snarky headlines.

Nitrous oxide gas is used to make cars go faster and whip cream into a delicious fluff; therapeutic nitrous oxide, surprisingly sweet-tasting, is used in dental procedures and for pain relief – or just a welcome distraction – during childbirth. Recreationally, nitrous oxide is huffed by the cool kids from brightly-colored balloons at festivals and bored teenagers straight from Reddi-Wip canisters in the supermarket aisle; by people with access to nitrous tanks, such as dentists or dental hygienists; by – purportedly – Hollywood actresses and wayward British princes; and, although this tends to go underreported, by people with other drug addiction or psychological issues.

But people have been having fun with nitrous oxide – even in the name of science – virtually since its discovery more than 240 years ago. In fact, it's only been the last 100 years or so that nitrous oxide has been more often used for "legit" purposes.

Nitrous oxide was first synthesized in 1772 by Joseph Priestly, one of Britain's foremost chemists and the man who invented soda water; he allowed nitric oxide (NO) to stand in contact with iron filings and water, yielding the gas N20. Priestly was a brilliant scientist, but also an Enlightenment thinker whose staunch belief that scientific inquiry would soon have everything, including dated institutions such as monarchy, sorted eventually landed him in de facto exile in America (this was after a mob of hundreds tore apart his lab and tried to burn down his house in 1791). Priestly's leaving didn't, however, mean the end of nitrous oxide investigations in Britain – although it wouldn't be for another 27 years until someone really looked at nitrous oxide.

That someone was Humphry Davy, a fearless scientific prodigy who'd taught himself French at the age of 14 – so that he could read chemistry books in French. "He was an incredible character, and incredible personality…. he was kind of pure genius. Unbelievably intense, unbelievably brilliant and incredibly ambitious," explained Mike Jay, author of The Atmosphere of Heaven, an account of scientific investigation into gases in the late 18th century.

Davy grew up in Penzance, a small port town on the Cornish coast; no one, Jay said, had ever come from Penzance. Blessed with an insatiable curiosity coupled with what was likely an eidetic memory, Davy grew up devising his own scientific experiments and making lab equipment out of whatever he had to hand – seaweed bladders, an enema syringe washed ashore after a shipwreck, the insides of a clock. In 1798, at age 18, he became a lab assistant at the Pneumatic Institute in Hotwells, a spa town in decline outside of Bristol, UK. The Pneumatic Institute was the brainchild of Thomas Beddoes, an eccentric, energetic polymath whose primary interest was medicine; it was a medical research facility whose aim was to investigate possible therapeutic uses of newly-discovered gases and chemicals to treat diseases of the lung that were spreading in the increasingly insalubrious air of industrialized Britain. Beddoes had hoped for live patients and he got them in their dozens, although not just consumptives, but people suffering from paralysis, palsy, and syphilis as well.

In April of 1799, Davy, in the Institute's laboratory and in between administering nitric acid to syphilitic sores, began to investigate nitrous oxide. He started by synthesizing the gas and promptly inhaling it himself. When he didn't die – and actually seemed quite invigorated by the experience – he and Beddoes began administering it to patients. They started with a 26-year-old man who, "after a course of excessive debauchery," was unable to move one side of his body. After inhaling the gas, the man soon regained mobility in his arm; Davy and Beddoes also noted that he and other patients seemed to look forward to their "dose of air" and "the pleasure it gave them."

By the summer, Davy had begun a rigorous course of self-experimentation, taking detailed notes not only the physical effects of nitrous oxide inhalation on his blood pressure or his body temperature, but also on his conscious state – how and what he was feeling when he took the gas. And he was feeling pretty phenomenal: Davy admitted that he was often breathing the gas just "for the sake of enjoyment." On full moon nights that summer, Jay said, Davy would fill up a bag of gas, grab his notebook, and get high up on Avon Gorge, overlooking the river Avon. His consumption was almost to the point of compulsion – he wrote that just seeing other people breathe was enough to make him want the gas.

But in the interest of scientific investigation, Davy couldn't rely solely on his descriptions of his own experiences for data. So he enlisted help. After the surgery was shut for the day and the invalids sent home, Davy's fellow experimenters – doctors, poets, surgeons, playwrights, and chemists – gathered in the Institute's drawing room. "It was kind of like a salon and Davy was the master of ceremonies," explained Jay. Davy would administer the gas, using a green oiled-silk bag he'd had made especially to hold the gas, to anyone who wanted to try it, the catch being that they had to write down their experiences. "There were a lot of wordsmiths, so of course there's a certain amount of competition in describing this sublime experience."

Among those who Davy invited were the Romantic philosopher-poets Robert Southey, the future Poet Laureate and author of "The Story of The Three Bears," and Samuel Taylor Coleridge, best known for his "The Rime of the Ancient Mariner." Their presence was part of Davy, himself a poet of the Romantic bent, trying to get to objectively grips with the subjective, phenomenological experience of being out of one's head on nitrous oxide. "If you want to construct a language of feeling, as Davy talks about, you can't do that with chemistry," said Jay. "You can't get from there to understanding what happens in the brain… you need people from different disciplines, chemical, medical, but also poetic."

This inter-disciplinary approach to understanding was a hallmark of the Enlightenment, an era of scientific and philosophical advancement that was only just now running out of steam. Man's capacity for knowledge seemed limitless and the distinctions of disciplines seemed hardly necessary: "At that time philosopher and chemistry were all looked upon as ways of understanding the world better," explained Dr. Stephanie Snow, professor of medical history at the University of Manchester and author of Blessed Days of Anaesthesia. "Science at that time was different from how we came to know science from the mid 19th century onwards. It was far more holistic in terms of what it brought together, in the way in which it tried to interrogate things using all the various disciplines."

Davy's experiments culminated on December 26, 1799 – Boxing Day – when he, chest bare and a thermometer stuck under one arm, walked into a specially-built sealed box and directed a friend and physician to keep pumping it full of nitrous oxide unless he passed out. After an hour and 15 minutes, Davy was still conscious and his system, he judged, was fully saturated; he exited the box and inhaled 20 more quarts of the gas from oiled silk bags he'd had made especially for huffing nitrous oxide. It was far and away the most nitrous oxide a human had ever inhaled. And Davy was really, really high, out of his head to the point of transcendence. "Nothing exists but thoughts!," he cried, after the sensation had returned to his limbs and he'd returned to earth. "The world is composed of impressions, ideas, pleasures and pains!"

Davy's work, dangerous and slightly mad, made him. In 1800, Davy, just 21, published his work on nitrous oxide, detailing his experiences with it, both objective and subjective, and touching on its potential uses as an anesthetic. Then, rather anticlimactically, Davy moved on to other things. He built a respectable career for himself, eventually becoming President of the Royal Society and a knight, and his self-experimentation was seen as "a kind of emblem of scientific heroism," said Jay, proof of his laudable commitment to science.

But the gas that launched his career was itself left to founder. Over the next 50 to 60 years, nitrous oxide would be used not as an anesthetic, as Davy had suggested, or even as a curative, but as a good time, or, to use the parlance of the time, a "frolic." By the 1820s, nitrous oxide had found a home on stage, usually as part of a variety act (this, by the way, was by no means the weirdest thing to show up on British or American stages in the 19th century). And though the names Davy, Southey, and Coleridge were frequently invoked in advertising materials, these were no meetings of expanding minds.

Typically, a show would involve a performer pretending to be a doctor and inviting audience members to come up on stage to try the gas; some shows would enact the chemical reaction to yield it on stage as part of the theatre. "It's kind of a marvel or curiosity of science, it's come from the world of science," Jay said, adding to that the tone of the show was along the lines of "in nitrous veritas," that under the influence of the gas one's true nature would be revealed. "It becomes a very popular low-brow entertainment."

This was how the general public experienced nitrous oxide – as "laughing gas," the name that it was now known by, and as part of a theatre-type experience (it was simply too difficult a chemical reaction to manage for at-home use). Fairly early on, before Davy's trials, nitrous oxide had traveled to America – by 1808, medical students at the University of Pennsylvania were sufficiently acquainted with it to both use it for partying and study. In America as in Britain, it languished on the traveling variety show act circuit. Even Samuel Colt, the inventor of the Colt revolver, toured a nitrous oxide show in the US and Canada in the 1830s, earning enough money to have prototypes of his revolving-barrel gun. Colt advertised his act with a quote from Southey: "The atmosphere of the highest of all possible heavens must be composed of this gas."

"It was looked upon very much as laughing gas, good for fun and frolic and public experiments and things it was not looked upon as a viable medical therapeutic agent," said Dr. Snow.

But it was in America that nitrous first began to be used as pain relief in dentistry, inspired by these frolics. In 1844, a dentist called Horace Wells who'd caught a laughing gas act in Hartford, Conn. was inspired to use the gas for his own wisdom tooth extraction. Wells declared a "new era in tooth-pulling" but, as Jay writes in The Atmosphere of Heaven, his attempt to demonstrate the gas at Massachusetts General Hospital in Boston in 1845 didn't go so well (the patient, not properly dosed, cried out). Wells's reputation was lost. (Wells is also a cautionary tale of the perils of self-experimentation: After the debacle at Mass General, Wells threw himself into experimenting with inhaling chloroform, going on a disastrous four-week bender in New York City. In a delirious fit, he rushed out onto Broadway and threw acid on two women; he was promptly arrested. While in jail on January 24, 1848, he committed suicide by slashing his femoral artery with a razor from his shaving kit. His death, however, was quite painless – he'd first managed to procure some chloroform to inhale.)

Despite Wells' failure, it actually was a new era for tooth pulling and more. By the 1860s, the gas was routinely used for dental surgery and increasingly being used in general surgery, even as "laughing gas frolics" remained part of variety acts. Why it took so long for the medical establishment to come around to the idea of anesthetics in general and to nitrous oxide in specific is a matter of social and psychological context. According to Jay, "Surgery was conceived as something where you wanted the patient to be awake, it was a kind of macho thing." The notion of anesthesia was, he said, heavily attacked by the medical profession for drawing attention to the "painfulness of the procedure" and making it less likely that people would go through with it. Then there was the fact that doctors were reluctant to have any potentially volatile chemicals and gases in their surgeries.

"What really moved it was that surgical procedures had progressed, there was much more that they could do. Surgeries were going on so long, that the ability of patients to withstand the pain was becoming a limiting factor," Jay said. "This is a very inconvenient story, what it says is that everything was there for decades but medical science ignored it for reasons that were nothing to do with the interests of the patient."

But Dr. Snow offers a somewhat different story. "Pain [in the early 19th century] was understood was to be by and large to be a benefit, it was like the body's safety net," she said. "If you were having an operation and you felt pain, that was actually a good thing because the pain was a trigger to the body to maintain its vitality. If you had a patient on the operating table and they sort of cried out and writhed in pain, that was good, it meant that they were alive, there was that vitality there." Nitrous oxide and other potential anesthetics, such as ether, were seen to depress the body, and suppress its natural inclination towards living; giving the appearance of death, wherein even pain couldn't rouse the sleeper, was something to avoided.

What changed wasn't only that doctors needed to operate on people for longer, but rather there was also a fundamental shift in understanding how the body worked in the first half of the 19th century. "There was a lot of work done on the nervous system that gives evidence that it's actually a hierarchy, that you can suspend some elements, like feeling, and yet maintain higher functions, like breathing," explained Snow. Snow noted that during the period from Davy's work on nitrous through the 1850s, import of opiates, for example, dramatically increased, revealing an increased appreciation with not being in pain.

And there were other changes. In Britain and America, the humanitarian movement was gaining steam. "From the 1820s onwards, you get the sense that causing anything pain, even animals, is against the basic impulse of a civilized society… Taking away pain is actually a blessing," explained Snow. "If fits with the broader movement of the antislavery movement, antivivisection, anti-experimentation on prisoners, it sort of ripples off those." Another was the increasing moral imperative towards self-control: "The act of crying out, the expression of physical feeling, was seen as weak self-control," said Snow; opiates, chloroform, nitrous oxide, ether, these were all looked on as helpful agents of suppressing that expression. And finally, private practice facilitated greater acceptance – essentially, doctors were more willing to provide anesthesia when the paying patient demanded it.

"By the time you get the 1860s it does become accepted that, certainly, for major operations, anesthesia is more of a benefit than a risk," said Snow.

Of course, people were still getting high off of nitrous oxide – to some degree, doctors and dentists more than anyone else, given that they had easy access. Snow noted the popularity of ether among doctors out of surgery hours: "The surgeon who has an operation during the day will have a dinner party at night and bring it home to sort of pass round to his friends," she said. Nitrous oxide was similar, and fairly popular among medical students.

But by the 20th century, the social acceptance of laughing gas had started to rub off. "Drugs started to be perceived as a social problem," Jay said, more than they had before. That changed the nature of how nitrous oxide, now "claimed" by medicine, was perceived. The philosopher-scientist investigations of Davy and certainly the philosopher-mystic investigations of psychologist William James, who famously used nitrous oxide in exploring and understanding religious mysticism in the 1870s, these kinds of enquiries weren't quite so permissible or laudable anymore. "When drugs are not perceived as a social problem, scientists take then and when they start to be seen as problematic, they stop taking them," explained Jay.

Through the middle of the century, scientific investigation of the experience of inhaling nitrous oxide fairly died out, even as use in other areas, such as on the labor wards, standardized. Meanwhile, recreational use was hampered by ease of access (although still part of the concert scene in the 1960s and '70s: The Grateful Dead toured with a tank of nitrous oxide, but well, they would and they could). Now, however, nitrous oxide is much easier to obtain and is no longer something that requires an in-house chemist: There are the steel "chargers," the little silver bullets containing nitrous oxide that are used in fancy whipped cream makers; inhaling it from a balloon filled by a tank; or sucking it out of cans of whipped cream. Pretty much everything can be purchased off eBay, in a headshop, or even just a grocery store.

Unsurprisingly, usage seems to be on the rise. In the UK, hippy crack is increasingly the monster under the bed for Britain's notoriously overheated press after the Home Office released figures in 2013 showing that nitrous oxide is the second most popular intoxicant among 16 to 24-year-olds. Jay, who lives in the UK, says the recent surge in nitrous use began as a "festival thing": "At dawn at festivals, you'd have carpets of these silver canisters," he said. Nitrous oxide is, according to the tabloids, a "lethal legal high," meaning they think it can kill you, but it's still legal to buy and possess; the only restriction is that it is illegal to sell to an under-18 if it's possible they may inhale it. Councils are worried – especially because nitrous oxide is rarely done alone: "Nitrous oxide is kind of pleasant but not particularly strong on its own. But if you're on ecstasy or cannabis or another combination of drugs, it's wow, it's more euphoric," explained Jay.

"N2O whippets" by GreenZeb – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

In the US, nitrous oxide was popular in the 1990s and, especially after Moore's hospitalization, news outlets worried that it was making a comeback. Nitrous oxide isn't precisely illegal, but it isn't entirely legal, either: Sale for recreational purposes that don't include making delicious desserts is prohibited in most US states, as are sales to minors. In reality, it's a halfhearted effort at best. Anecdotally, as in the UK, nitrous oxide is frequently sold outside concerts and at festivals – the Nitrous Mafia, for example, is an east coast ring of festival-going nitrous dealers who offer deals like four balloons for $20. They pretty much operate out in the open because, well, law enforcement and security usually have bigger, more illegal fish to fry.

But real figures about nitrous oxide use are not easy to track down; nitrous is often lumped in with other "volatile substances," such as paint, glue, VCR head cleaner (which must be made solely for the "legal high" market these days), gasoline, and, Freon. For one thing, surveys tend to ask general blanket questions about whether the respondent has ever used "inhalants," rather than specific questions about the more than 1,000 household and common items a person could conceivably sniff and get high on; the latter tends to yield higher numbers. However, according to the CDC's most recent Youth Risk Behavior Survey, from 2013, 8.9 percent of American high school students admitted to using inhalants, a figure on the lower end of the spectrum; other surveys from the last 15 years put the figure as high as 20 percent. Girls are more likely than boys to use volatile substances to get high, as are 9th graders are more likely than kids in older grades (but those numbers might not be accurate – inhalant abuse is often associated with dropping out of school, so by the time the older grades are surveyed, the inhalant abusers aren't there any more). Teens in rural and impoverished areas are also more likely to abuse inhalants; people with substance abuse and mental health issues often also abuse inhalants. Adult statistics are difficult to find – although dentists and dental hygienists tend to be the ones with the access and the addiction to nitrous oxide – but it is primarily a problem of youth.

"N2O cracker" by GreenZeb – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

So why is nitrous oxide at least legally frowned-upon? Davy seemed to survive his extended dalliance with nitrous oxide with no long-term side effects, but the fact remains that nitrous oxide isn't particularly good for you. There is a risk of asphyxiation if the nitrous isn't properly mixed with air; exposure to cold temperatures of the gas isn't terribly good for your lungs; falls due to passing out can be dangerous; and prolonged use could result in sores in the mouth, possible liver damage, vitamin B12 deficiency and neuropathy. It can even, though very rarely, lead to death: There's phenomenon called "Sudden Sniffing Death Syndrome," which is exactly what it sounds like – a user, whether her first or her 50th inhalation, drops dead of heart failure. Statistics are murky, but in the UK, 52 deaths since 1971 have been linked to nitrous oxide inhalation; in the US, in 2002, 40 people died as a result of general inhalant abuse.

But actually, very little is known about the actual effects of nitrous oxide use because it's very little studied.

"Inhalant abuse is really an underappreciated problem," attested Dr. Matthew Howard of UNC School of Social Work and one of the few researchers in America looking at the problem of inhalant abuse. "It's one of the most harmful, but it's really under-recognized, not only by the general public but by experts and scientists as well."

Now, to be clear, we're not talking about the occasional festival user or somebody who may try a balloon at a party every once in awhile – that's probably not good for you, but neither is it really likely to cause long-term damage. Real, chronic inhalant abuse, however, is pretty scary stuff and it usually happens to kids.

The real worries for excessive use of inhalants is also what's going on along with them: "Casual use is quite widespread, but heavy dependent use tends to be less common and tends to be associated with co-morbid psychiatric problems and to co-exist with other dependence issues," said Howard. In other words, if you're really into inhalants – and nitrous oxide is one of the big ones – you've probably got some other problems as well. And if you don't know, you will: In his research, Howard has definitely found a correlation between early onset inhalant abuse and greater use of other drugs. Moreover, in teenagers, use of inhalants, including nitrous oxide, has been associated with a host of negative outcomes, including anti-social behavior and, per the gateway drug model, moving on to harder drugs such as heroin. Howard and his colleagues also found that, far from the airy flights of fancy and introspection of Davy's nighttime nitrous oxide salons or even the laughing gas "frolics" of the 19th century, the abuse of volatile substances "appears to be an act of desperation committed by troubled individuals in dire circumstances, rather than an act of pleasure-seeking." That's rather grim.

And it serves to underscore the fact that nitrous oxide is an intoxicant that we don't really know how to feel about. The bigger problem with nitrous oxide abuse is one of image: That nitrous oxide is considered "soft" can in many ways gloss over the real problems associated with inhalant abuse. Howard says that while other countries, including Canada, Australia, and New Zealand, are waking up to the real problems of inhalant abuse, the US has not. What's needed isn't so much a big clampdown in legislation on things like whipped cream canisters, but rather an attention paid to where the problem is happening, why, and how to treat it.

"It is a very low priority item in the drug research and treatment area, most treatment programs don't even ask users if they use inhalants. There are no treatment models specifically to treat inhalant abuse in adolescents, we don't know that much about the users themselves or the medical issues around it," said Howard. "There's no question that this is a hidden epidemic."

For now, for the majority of people, nitrous oxide remains largely what it's been since Davy took his first huff from the green oiled-silk bag: A frolic, a diversion, a way to touch the sublime for even just a moment, damn the consequences.