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Wikipedia deems this topic significant enough to merit its own article:

Fart lighting, or pyroflatulence, is the practice of igniting the gases produced by human flatulence, often producing a flame of a blue hue. The fact that flatus is flammable, and the actual combustion of it through this practice, gives rise to much humourous derivation. Other colors of flame such as orange and yellow are possible with the color dependent on the mixture of gases formed in the colon.

Although there is little scientific discourse on the combustive properties of flatus, there are many anecdotal accounts of flatus ignition and the activity has increasingly found its way into popular culture with references in comic routines, movies, and television; including cartoons.

Unfortunately, its sources, which include Answers.com and YouTube, leave much to be desired. For starters, YouTube videos can easily be faked.

Is there any evidence that flatus is flammable? If so, are there any verified cases of its ignition?

  • 1
    The Mythbusters tested this – Oliver_C Apr 18 '11 at 12:48
  • @Oliver: Of course! ;-) (I found that linked on the talk page after I posted the question, when I went to check how many times that article had been brought up for deletion.) Incidentally, I'm not twelve. I'm just working my way backward through Freud's fixations. Unfortunately, another user beat me to the first. – Patches Apr 18 '11 at 13:28
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    I read the title as "fetus" and was a little surprised. Now I am curious in a bad way. – MrHen May 16 '11 at 15:03
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I very much wanted to base my response on the empirical data valiantly collected by my old college roommate. However I chose not to, remembering that the plural of anecdote is not data.

However, flatus, farts, or whatever it is you'd like to call 'em can be flammable under the right conditions. This is mostly because they contain methane and hydrogen sulfide.

Remember, each fart is as unique as the person trying to light it, and whether or not you can light a fart depends mostly on the volume of gas produced at any given time, the strength of the flame, and distance from ignition source.

Most farts/flatus are made up of

  • hydrogen sulfide (flammable)

  • methane (flammable)

  • oxygen (not technically flammable, but aids combustion)

  • Nitrogen

  • Carbon Dioxide

  • Many other chemicals and compounds which don't really matter for this question.

(this can be referenced in the wiki article for flatulence.)

The chemistry of it all looks like something like this:

Methane burns in the presence of the O2, (ΔHc = -890 kJ/mol), as:

CH4 + 2O2 → CO2 + 2H2O

Hydrogen sulfide also combusts (ΔHc = -520 kJ/mol) to

2H2S + 3O2 → 2SO2 + 2H2O

Found a link for the basic chem of methane combustion here. Mostly because it's hard to write a chemical equation in this post, sorry.

A link to the mythbusters experiment is here.

  • The plural of flatus would be flati. If it's from the latin word, that is :) – Lagerbaer Apr 18 '11 at 22:27
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    @Lagerbaer: A little learning is a dangerous thing. Flatus is fourth declension, so its plural is flatus. Monkey Tuesday had it right. – TonyK Apr 19 '11 at 20:25
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    Honestly, I took a guess. As far as I'm really concerned the plural of flatus remains "farts". Cheers. – Monkey Tuesday Apr 19 '11 at 22:27
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    @mon can you please add references (wikipedia is OK for the composition of flatus) – Sklivvz Jul 24 '11 at 19:38
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    @sklivvz sorry it took so long, added a reference per your request. – Monkey Tuesday Aug 9 '11 at 21:43

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