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You've probably never tried to carry a mercury thermometer or barometer on a plane.
你可能从没把水银温度计或气压计带上飞机吧。
But even if you really wanted to, you can't in the U.S., unless you happen to work for a government weather agency.
但即使你真的想将它们带上，在美国完全不行，除非你恰好为政府气象局工作。
That might seem like another weird restriction, but there's an important reason for it:
这听上去可能像是一项奇怪的限制条例，但却有着重要的原因：
That tiny bit of liquid metal is fascinating, but really dangerous.
那一丁点的液态金属很神奇，但也很危险。
Mercury is the only metal that's a liquid at room temperature,
汞是在室内温度中唯一以液态形式存在的金属，
which is why it's sometimes called quicksilver — which comes from the Old English for "living silver", not the X-Men.
这也是汞有时被称为水银的原因——这源于古英语“活的银”，而不是X-Men里的快银。
And it's especially useful for thermometers because of how much it expands when you heat it.
由于水银加热时会膨胀，所以对温度计特别有用。
It has what's called a high coefficient of thermal expansion,
水银的热膨胀系数高，
which means that when you heat it up a little, it expands a lot.
这就意味着当你将其稍微加热，就能快速膨胀。
So that way, you don't need to use a magnifying glass on your thermometer to see if you need a sweater.
因此，你不需要用放大镜查看温度计添衣加暖。
Mercury also forms mixtures, or alloys, with a lot of other metals very easily.
加上许多其他金属，水银也能轻易产生混合物或合金。
An alloy with mercury in it is called an amalgam, and they're useful for all sorts of things.
混有水银的合金被称为汞合金，就能用于各种事物之中。
For example, if you've ever gotten a silver filling at the dentist,
例如，如果牙医给你镶了银牙，
that's a harmless amalgam of metals like mercury, silver, and copper.
这就是一种如汞、银和铜之类的金属混合成的无害汞金属。
But some amalgams aren't so harmless.
但一些汞合金并非无害。
Like, when mercury comes into contact with pure aluminum, things get pretty quickly.
比如，当水银和纯铝接触，很快事情就会变得怪异。
And you definitely don't want it in your teeth.
你绝对不想让这类物质进入你的牙齿。
We make so many things — like airplanes — out of aluminum because it's so durable.
由于铝的耐用性，我们用铝制造了很多东西，如飞机。
When most metals are exposed to oxygen, they rust and degrade over time.
当大多数金属暴露于氧气之下，就开始生锈退化。
But when aluminum reacts with oxygen,
当铝和氧气产生反应时，
it forms aluminum oxide, which is non-reactive and protects the pure metal underneath.
会产生不反应的氧化铝并保护底部的纯金属。
Normally, this is great. Unless there's mercury involved.
通常，这样很好。除非其中有水银的掺和。
If mercury can get to the pure aluminum, like through a scratch on the plane,
如果水银接触到纯铝，比如飞机上的划痕，
it immediately starts to react and seep into the metal, forming an amalgam.
就会立即开始产生反应并渗入金属之中，形成汞合金。
When that amalgam meets the air, it stills turns into aluminum oxide — except this time,
当那种汞合金遇上空气，仍会转化为氧化铝——除了这一次，
because there's mercury involved, the reaction doesn't stop.
因为有水银的掺和，这种反应不会停止。
And the aluminum oxide starts to grow out of the plane like some kind of cyberpunk plant.
氧化铝开始在飞机上不断扩张，比如某种数字朋克飞机。
And the mercury isn't consumed during this reaction, so it keeps reacting with more aluminum,
此反应过程不消耗水银，所以水银就会和更多铝继续进行反应，
and the whole cycle continues until either the mercury evaporates or there's no aluminum left.
整个反应循环继续，直到水银蒸发或铝被耗尽。
Which is why you don't want your old-timey thermometer anywhere near a plane.
这就是为什么你不希望你的老式温度计接近飞机的原因。
If you have enough of it, the mercury can slowly destroy the integrity of the plane.
如果温度计足够的多，水银能够慢慢地摧毁整架飞机。
And even though a tiny amount of mercury probably won't do fatal damage,
虽然小剂量的水银可能不会造成致命毁坏，
mercury spills have damaged and even grounded planes in the past.
但在过去，水银泄露确实造成飞机的损坏甚至着陆。
But conveniently, even if you really did want to measure the temperature on your plane,
但即使你真的想要在飞机上测温度，
most thermometers these days don't have mercury in them, since it's also toxic if it enters your body.
如今大部分温度计都不含水银，因为水银进入你的体内也是有毒的。
So even though some air travel laws change over time,
因此虽然一些航空法随时代在改变，
you probably won't be bringing your mercury thermometer on board any time soon.
你可能很快就不会带水银温度计上飞机了。
And I'm okay with that.
我无所谓啊。
Thanks for asking, and thanks to all our patrons on Patreon who keep the answers coming!
谢谢提问，谢谢Patreon上一直提问的观众！
If you'd like to support the show and submit a question, you can go to patreon.com/scishow.
如果你想要支持科学秀并向我们提问，你可以登录patreon.com/scishow。
