farting or ‘breaking wind’, is releasing gas from the anus. The English word ‘fart’ has been around for a long time; in 1386, Chaucer wrote: ‘This Nicholas anon let flee a fart.’

The medical word for a fart is flatus (rhymes with hiatus); farting is flatulence — which is sometimes used to mean belching as well. ‘Pease and beans are flatulent meat’ (Blount, 1674) — and there are flatulently, flatulentness, flatuosity, and flatuous — ‘If a man eat them [mulberries] alone … they swell in the stomack and be very flatuous’ (Holland's translation of Pliny, 1601). However, there seems to be no verb ‘to flatulate’.

Some old people claim that they fart more with increasing age. Doctors do not regard flatulence as a problem in the absence of other serious symptoms.

Farting has always been viewed as vulgar and comical. In the opening scene of Aristophanes's comic play The Frogs, the slave Xanthias, trying to raise a laugh from his master (and the audience), says:μηδ' ὅṯί ṯοσοῦ̑ṯον ἄχθος ϵ̔ρ' ϵ̔μαυṯῷ ϕέρων,
εἰμή καθαίρήσεί ṯίς, ἀροραρδήσομαί;
which means, roughly, ‘Well, how about this: If nobody will take away my pack, I'll let a fart and blow it off my back!’

Noise

The Roman Emperor Claudius felt strongly that people should have no inhibitions about farting, even at parties, and issued an edict to that effect. In the 1530s, Erasmus wrote that to hold back wind is dangerous, but that one should hide the sound with a cough, for ‘the sound of farting, especially of those who stand on elevated ground, is horrible.’ Today most people try to hide the sounds of farts in public places, and smart public lavatories in Japan are equipped with wall-mounted gadgets that make a loud flushing noise when a button is pressed, thus covering the noise of a fart the occupant feels is coming.

However, one man made his living from the sounds of his farts. Joseph Pujol, who called himself Le Petomane, found he could inhale air through his anus, and developed amazing control of the farting sounds he made. He appeared on stage at the Moulin Rouge in Paris, wearing a red tail-coat and black satin breeches, and delivered a long repertoire that ranged from the sound of a young girl farting to that of a strip of calico tearing. He blew out candles, and, through a tube, played Au claire de la lune on a little flute, and smoked a cigarette. During the 1890s he could earn 20 000 francs in one day at the box office, while Sarah Bernhardt earned only 8000.

Chemistry

Farts are actually gas bubbles produced in the colon by the action of bacteria on food. The idea that farts are bubbles of swallowed air that have been passed right through the digestive tract has been disproved by American research: the gases in farts are mainly carbon dioxide (up to 50%), hydrogen (up to 40%), nitrogen (about 20%), and methane. One person in three produces about 15% methane; the rest of us produce none. This probably arises because we all have hundreds of types of bacteria in the gut, and they vary widely from person to person.

Hydrogen and methane are highly flammable, which has led to some tragic accidents on the operating table. In April 1978, for example, at the University Hospital in Nancy in France, surgeons were trying to remove a polyp from the colon of a 69-year-old man, using an electrically heated wire loop. When they switched on the power to the loop there was a loud explosion inside the colon, and despite emergency surgery the patient died within minutes. Their conclusion was that even though his bowels had been thoroughly cleared and seemed to be completely clean, an explosive mixture of air and hydrogen or methane must have collected. After this incident the official policy was changed, and such patients were insufflated with carbon dioxide before and during surgery.

There have been rumours that cases claimed to be spontaneous human combustion were in fact caused by farts being ignited by electrostatic sparks from synthetic fibres in underwear.

A vet in Holland was smoking a cigarette while working on a cow. It farted, and after the subsequent explosion the barn burned to the ground. Cows and other ruminants produce methane and other gases from both ends. In 1799 these gases were thought to have possible medical benefits, and were tried out on the patients at Dr Beddoes' Pneumatic Institution in Bristol, under the supervision of the medical superintendent, the 19-year-old Humphry Davy.

Today the farts from cows are asserted by some to yield enough methane to cause a greenhouse effect in the upper atmosphere, thus contributing seriously to global warming.

Beans

Almost all people fart, typically once an hour, producing between 200 ml and 2 litres a day, although both rate and quantity can be enormously increased by stress, and by eating particular foods — notably cabbage, onions, and beans.

Foods are broken up by the acid in the stomach to produce sugars and various other fragments. The sugars reach the small intestine in the form of oligosaccharides — a few sugar molecules stuck together. We digest most of these oligosaccharides by hydrolysing them with the aid of enzymes to form simple monosaccharides, which in turn are absorbed into the bloodstream.

However, there are three rogue oligosaccharides — raffinose, stachyose, and verbascose — which we cannot digest. Hydrolysis (breakdown) of these requires the enzyme α-D-galactopyranosidase, which does not exist in the human gut. So they pass through into the large intestine, where bacteria digest them anaerobically to make carbon dioxide and hydrogen.

The flatulent effects can be reduced, some people claim, by soaking dried beans for at least 5 hours, then draining, rinsing, boiling for at least 10 minutes in fresh water, and draining and rinsing again before the final cooking.

Alternatively, proprietary medicines are available containing the missing enzyme, and the manufacturers claim that if you take these (drops or pills) when you eat beans you will be able to digest the rogue sugars, and you will not fart. Indeed, the American manufacturers go further, and sell a similar product for pets, to curtail the farting of cats and dogs!

Smell

The smell of farts can be memorable. Sir Thomas More, Chancellor to Henry VIII, was famed for his witty Latin epigrams, some of which were quite fruity:Sectile ne tetros porrum tibi spiret odores;
Protinus a porro fac mihi cepe vores;
Denuo foetorem si vis depellere cepe:
Hoc facile efficient allia mansa tibi;
Spiritus at si post etiam gravis, allia restat;
Aut nihil, aut tantum, tollere merda potest.
Sir John Harington, incorporating his own puns, translated this as follows:If leeks you leeke, but do their smell disleeke,
Eat onions, and you shall not smell the leeke:
If you of onions would the sent expell,
Eat garlick, that shal drown the onions smell;
But against garlikes savour, [if you smart],
I know but one receipt. Whats that? [A fart].


Martin Luther boasted he could ‘drive away the evil spirit with a single fart.’ In 1825 Thurlow asserted ‘There are five or six different species of farts’ — a fact known to every schoolchild.

The smell was for many decades thought to be due to the traces of indole and scatole the gas bubbles pick up from the faeces, but recent research suggests that at such concentrations these compounds smell only of mothballs. The smell of farts has been shown to come mainly from sulphur compounds; hydrogen sulphide and organic sulphides. In general, vegetarians fart more than meat-eaters, but their farts are less smelly. However, some vegetarians are said to have more sulphur-producing bacteria in their guts, and so produce much smellier farts.

When a fart is suppressed the gas may be absorbed by the gut. Most of the hydrogen and other gases eventually escape in the breath, but luckily the smell does not get through.

Adam Hart-Davis