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  • We're in the archives of the Royal Society in London again, and I want to talk to about methane and methane and coal mines because I've already so knew on some of the videos home.

  • Etain can explode when it's mixed with air on because CO is originally formed from organic matter very frequently in coal mines, you get methane gas and methane gas Doesn't smell, has no color on DDE.

  • In the early days of coal mining, people never knew it was there, and suddenly there would be an explosion.

  • And the reason they're being explosion is because they use candles to light the mine.

  • While they were digging, there was a big scientific race to try and invent a safe lamp that would help the miners know when there was danger but wouldn't blow them up.

  • So if you think about it, you've got to try and have a naked flame in a coal mine where if there is gas there, the explosion wouldn't spread.

  • So before I tell you how it was solved, let's go and see some of the things that they're here in the archive, which explains how it was done.

  • As usual, I have got my colleague Rupert, who's goingto find some things to bring this all to life.

  • Gosh, that's really good.

  • What we've got here looked pretty miserable.

  • But this was the lamp invented by Sir Humphrey Davy in 18.

  • One can argue exactly when.

  • 18.

  • 13.

  • Also, this is the lamp he made, which solves the whole problem on dhe.

  • The key to it is this gauze that you can see here.

  • So first of all, before I explain what the goals does, let's see Rupert come and show me.

  • So Humphrey Davy, who was working at the Royal Institution, tried all sorts of different designs with his assistant, Michael Faraday, and they try different sort of lamps to see whether if they exposed this to me thing, it would explode.

  • And this is the drawing they really made.

  • Am I allowed to touch it?

  • So here and underneath, I think, is another drawing of a lamp that didn't work.

  • You say just looks like a lantern with the chimney.

  • This is there his actual writing where he describes his apparatus.

  • It begins the first apparatus that I made.

  • I'm not.

  • So if many of you have bean in the middle of an explosive mixture.

  • But what happens is when you light a match, the reaction starts just on the match.

  • And because when methane burns and like CO two and steam it occupies a bigger volume, the pressure goes up, so pressure wave moves outwards, and as it moved outwards, it compresses the gas that it meets.

  • And so the pressure goes up and the temperature goes up on.

  • The reaction goes faster, so it builds up and up and up.

  • So by the time it gets it small distance away, it's really traveling very fast with the little rate on DDE.

  • What's David discovered, presumably with Faraday, was that if you have a flame inside the goals, the gas can start burning in the Gores.

  • But the flame cannot go through that doors because the metal goals cools the gas enough to stop the reaction.

  • So if you were a miner with one of these lamps in an explosive atmosphere, what you will suddenly notice is that the color of the flame changes starts burning.

  • I think, with a more bluish flame, and you know something's wrong.

  • But you're still alive and you know it's time to leave or turn up the ventilation.

  • But until that point, if somebody had a lamp and was in an explosive atmosphere, they never knew about it because they've been blown up.

  • This lamp here, or this piece of tubing, is the lamp that Davy made that proved his discovery on Dhe.

  • Like many pieces of historic equipment, it doesn't look very exciting.

  • But this is what sparked.

  • The idea that sparked the idea is the wrong metaphor here.

  • But you understand what I mean.

We're in the archives of the Royal Society in London again, and I want to talk to about methane and methane and coal mines because I've already so knew on some of the videos home.

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戴維燈--視頻週期表。 (Davy's Lamp - Periodic Table of Videos)

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    林宜悉 發佈於 2021 年 01 月 14 日
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