Playing with mercury

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Fishnut
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Playing with mercury

Post by Fishnut » Fri Jun 10, 2022 6:56 am

When I was a kid I spent a lot of time reading The Children's Encyclopedia by Arthur Mees. If you're not aware, they're a 10-volume set written in the post-war years for kids, having sections on history, nature, art, geography, etc. My favourite sections were the stories from around the world (which played a major part in becoming atheist - it's very hard to tell the difference between Norse or Japanese mythology and Bible stories without anyone there to guide you) and the Wonder section, which was set up as a series of Q&As. Two questions really stuck with me as they were about mercury. I knew, even back then, only of mercury as an incredibly dangerous substance so to read about people playing with it casually always intrigued me.

These are the two questions:
Why does quicksilver run away when we touch it.jpg
Why does quicksilver run away when we touch it.jpg (37.64 KiB) Viewed 475 times
Why does quicksilver roll up into little balls.jpg
Why does quicksilver roll up into little balls.jpg (42.92 KiB) Viewed 475 times
I have recently found a couple of mercury thermometers. I want to get rid of them as their both in Fahrenheit (though maybe I should keep hold of them for a while). But before I do, I'm finding it very hard to pass up this opportunity to experience the answers to these two questions. However, there's a few practical considerations to consider before I do, and I thought if anyone could help me overcome them, it would be the hive mind.

Question 1 - how do I safely break the thermometers open to get to the mercury?
Question 2 - how do I safely dispose of the mercury after?
Question 3 - is there any safety equipment (gloves/mask etc) that I should wear while playing with the mercury?

I'm not envisioning long exposure but figure it's best to protect myself as much as possible. Also, I suppose I should ask, am I being completely reckless and irresponsible in my plan?
it's okay to say "I don't know"

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Re: Playing with mercury

Post by tenchboy » Fri Jun 10, 2022 7:32 am

There is a set of A.M.C.E. still down at Mum's, still on the landing at the top of the stairs, where I used to read them.
I once played with Mercury, maybe from a broken thermometer, it definitely is as much fun as it sounds.
No idea (beyond the obvious) how you might now do this safely.
I also remember asking the local chemist for some phosphorous because in another one of those 'Wonder' sections it said you could make a useful lamp by dropping the phosphorous in a jar of oil in which it would then glow; I don't remember it mentioning the problem of safely getting the phosphorous home and into the jar of oil.
If it wasn't in A.M.C.E. I don't know where else it might have been.
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Re: Playing with mercury

Post by Opti » Fri Jun 10, 2022 8:16 am

I used to have those encyclopedias. Also used to mess about with mercury in the chem lab at school in the 60's. No PPE. We were also shown how to make NI3, a process used by boys at lunchtime in the (unlocked) lab to do pranks.

Life was so carefree and innocent back then.
Time for a big fat one.

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Re: Playing with mercury

Post by tom p » Fri Jun 10, 2022 8:24 am

You can safely play with atomic mercury (the form in thermometers. The dangerous form is methyl mercury, where the methyl group enable the mercury to pass through the lipid walls of our cells and into your bloodstream and, from there, through the blood-brain barrier & into the brain.

If memory serves, my old A-level chemistry teacher reckoned one could safely drink mercury from a thermometer (presumably after separating it from the broken glass); however i wouldn't treat that as gospel

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Re: Playing with mercury

Post by shpalman » Fri Jun 10, 2022 8:25 am

Liquid metallic mercury is not particularly dangerous. It doesn't give off a huge amount of vapour but still, don't put your nose over it, and play with it in a ventilated area at least.

The hardest thing is that it's very difficult to pick up off the floor.
molto tricky

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Re: Playing with mercury

Post by tenchboy » Fri Jun 10, 2022 8:39 am

shpalman wrote:
Fri Jun 10, 2022 8:25 am
...
The hardest thing is that it's very difficult to pick up off the floor.
That's the one! :D
It wasn't a broken thermometer, it was from an actual tube/phial of the stuff that was in grandad's workshop when he moved into a smaller retirement flat. (Prob circa 66)

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Re: Playing with mercury

Post by tenchboy » Fri Jun 10, 2022 8:41 am

Oh and don't use aluminium: the mercury wins (the reason thermometers are discouraged on aeroplanes) (unless that's a myth too)

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Re: Playing with mercury

Post by Gfamily » Fri Jun 10, 2022 8:52 am

For some reason our primary school had a bottle of mercury which got spilled on a tiled floor.
I remember chasing the beads along the grooves and trying to push them together to get them to merge. As the beads collected dust on their surface, they didn't automatically come together. I can't remember how it was collected up at the end.

Mind you. it wasn't the most safety conscious school, as top year pupit were were allowed to stay in the classroom unsupervised over lunchtime, and my friend Michael and I used to melt lead (in jar lids) on the open coal fire.

Fun times
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Re: Playing with mercury

Post by Gfamily » Fri Jun 10, 2022 9:01 am

tenchboy wrote:
Fri Jun 10, 2022 8:41 am
Oh and don't use aluminium: the mercury wins (the reason thermometers are discouraged on aeroplanes) (unless that's a myth too)
Liquid Metal Embrittlement. I recall going to a young scientist talk (i.e. for an audience of YS), where the speaker demonstrated rubbing a piece of Gallium on a rod of Aluminium, which he could then snap like a twig.

The gallium bonds to the aluminium in a slightly exothermic reaction that melts the gallium and allows it to flow along any flaws in the aluminium microcrystalline bonding. If there is any tension on the rod, the micro flaws will propagate and the rod will snap.

There was something about not being able to use certain steel alloy tools on stealth fighters as the alloying element had a similar destructive effect.
My avatar was a scientific result that was later found to be 'mistaken' - I rarely claim to be 100% correct
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Martin Y
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Re: Playing with mercury

Post by Martin Y » Fri Jun 10, 2022 9:12 am

tenchboy wrote:
Fri Jun 10, 2022 8:41 am
Oh and don't use aluminium: the mercury wins (the reason thermometers are discouraged on aeroplanes) (unless that's a myth too)
I remember our chemistry teacher demonstrating that: sandpapering a little sheet of aluminium and rubbing mercury on it. As the amalgam formed and stopped the protective oxide layer reforming he rubbed dilute acid on it and it attacked the aluminium very impressively, reminiscent of sodium in water.

It was a compelling demo of the fact that aluminium really is very reactive and only its tough oxide layer makes it a practical structural material, and also of why mercury thermometers and barometers aren't allowed on aluminium planes.

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Re: Playing with mercury

Post by insignificant » Fri Jun 10, 2022 9:16 am

1 - if you score the end of the tubes with something hard / sharp enough, they should just snap, but I'd wear gloves in case they shatter

2 - it's hazardous waste, so will need to be taken to a hazardous waste collecting place in a sealed container

3 - I don't think you need any PPE, occasional exposure to elemental / atomic mercury isn't a problem, just don't lose any of it and wash your hands

When I was at school, one of my teachers liked to pour a load of it in to a big transparent container and cover it with it water (vapour trap) and allow people to put their hands in it so they could see what immersion in something 13.5 x denser than water feels like

I like old thermometers though

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Re: Playing with mercury

Post by veravista » Fri Jun 10, 2022 9:44 am

Ha! We did that immersion test when I was at school - weirdest feeling ever. Never did me any h

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Re: Playing with mercury

Post by nekomatic » Fri Jun 10, 2022 9:45 am

Allegedly there were university labs that could no longer be used because so much mercury had been irrecoverably spilt in them over the decades that the vapour concentration from its gradual evaporation exceeded safe levels. I doubt there’s any risk at all from one thermometer’s worth even if you dropped the whole lot but you should plan for how not to spill it, I guess.

I’m not sure of the best way to break the thermometer but obviously if you want to play with the mercury in your hands then you want to make sure there are no little bits of glass floating in it first. Glass will be much less dense though, so I guess it should come to the surface of the drop.

I also have a mercury thermometer kicking about awaiting disposal and keep failing to get round to finding out how to do it, even though the guys at the council recycling place are usually very helpful and would probably tell me.
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Re: Playing with mercury

Post by shpalman » Fri Jun 10, 2022 10:22 am

nekomatic wrote:
Fri Jun 10, 2022 9:45 am
Allegedly there were university labs that could no longer be used because so much mercury had been irrecoverably spilt in them over the decades that the vapour concentration from its gradual evaporation exceeded safe levels...
I seem to remember that from my time at Cambridge.

https://www.newscientist.com/article/mg ... ft-behind/
molto tricky

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Re: Playing with mercury

Post by IvanV » Fri Jun 10, 2022 10:53 am

In the "old days", like the 1970s, it was quite common to see little balls of mercury on the floor of dentists surgeries. It was found that dental staff who wore open-toed sandals experienced a larger level of mercury uptake into the body, and could be thus identified from the mercury content of their toenail clippings.

If you work in a location with persistent or large exposure to mercury, then that isn't very good for you. It is especially not good for developing children. But playing with a small amount on a handful of occasions is a small exposure. Though you really don't want to swallow some. There is some amount of mercury in urban air, and in the food chain, and environment generally, so you get a small amount of mercury exposure regardless.

I would be very careful to release the mercury into a container that entirely contains it, so you can afterwards dispose of all of it, and not have balls rolling around your room that are hard to find/pick up, etc.

Mercury and aircraft

This 2009 document lists just five known cases of mercury spills on aircraft. Three were written off by insurers. But of those, two were cleaned and put back into service. The third was reduced to spares. The other two were cleaned and put back into service.

So there is no known case where mercury has actually caused notable damage. The real reason that airlines are so hot on preventing mercury on-board is that, because of the theoretical risk, regulations and insurance will require them to carry out a very expensive cleaning procedure, which on occasion has been so potentially expensive the aircraft has been written off.

Mercury, it can clearly be demonstrated, can cause structural damage to aluminium. But only in the immediate presence of mechanical (or possibly chemical damage) to the protective oxide coating that automatically reforms after each incident of mechanical damage to it. So it requires two things to go wrong - the mercury rolling around, and then that further damage to that alumnium oxide coating in the immediate presence of the mercury. If balls of mercury were routinely rolling around in aircraft in the aftermath of common spills and breakages, then probably from time to time those two things would coincide. As in practice the risk of mercury release on aircraft has been so controlled, such that mercury spills are very rare, it seems that coincidence has, apparently, not yet happened.

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Re: Playing with mercury

Post by jaap » Fri Jun 10, 2022 1:12 pm

One of my older books of magic tricks describes a trick that was later used in an episode of Jonathan Creek - the vanishing statue. A small metal statue is hidden from sight and later found to have disappeared. Basically it is made of frozen mercury, and as it melts the mercury runs off into a compartment in the base of the statue. It was probably some amalgam rather than pure mercury, as the latter freezes at -39 C. I wonder if this was ever performed for real.

I used to have a mercury tilt switch from a Honeywell thermostat. It had a decent amount of mercury in it, and you could safely play around with it - shake it to feel the inertial mass, tilt it to see how it wrapped around the metal contacts. I never dared to break it, and eventually got rid of it at a recycling centre.

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Re: Playing with mercury

Post by Martin Y » Fri Jun 10, 2022 1:37 pm

I added small mercury tilt switches to a batch of commentators microphones* about ten years ago. Looked at making more recently but the usual component suppliers don't want to sell 'em. I tried other types of tilt switch, typically with some kind of ball bearing inside, but they just don't switch as silently and reliably as mercury with the tiny voltages involved.

*So at the cricket or wherever they can have an emergency spare mic on the table in front of them. While it's lying face down its turned off. Pick it up and it's live.

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Re: Playing with mercury

Post by tom p » Fri Jun 10, 2022 2:44 pm

Martin Y wrote:
Fri Jun 10, 2022 1:37 pm
I added small mercury tilt switches to a batch of commentators microphones* about ten years ago. Looked at making more recently but the usual component suppliers don't want to sell 'em. I tried other types of tilt switch, typically with some kind of ball bearing inside, but they just don't switch as silently and reliably as mercury with the tiny voltages involved.

*So at the cricket or wherever they can have an emergency spare mic on the table in front of them. While it's lying face down its turned off. Pick it up and it's live.
Lesmts would have strongly approved.
Wonder what he's up to these days

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Re: Playing with mercury

Post by Pishwish » Fri Jun 10, 2022 2:46 pm

It seems a shame to destroy a thermometer, especially if it can be stored safely or given to someone who might like it . We still have one, though it has a centigrade at well as a Fahrenheit scale. Always seems a bit more trustworthy than an electronic one, and I think it is a more interesting artifact than, say, an old Walkman. (I think I have a small amount of mercury in a container in the garage, I did get a bit nervous of it when I saw a clip of a bowl of room temperature mercury in uv light, which revealed substantial vapour loss that could not be seen in ordinary lighting conditions.

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Re: Playing with mercury

Post by Trinucleus » Fri Jun 10, 2022 3:15 pm

Mercury is fun stuff, but I'm sure at one point there had to be a barrier to the outside world to stop people breathing in the vapour. That always struck me as daft for short term exposure to a liquid with a boiling point of 300+ degrees.

I used to have a (sealed) maze where you had to manouevre a globule of mercury into the centre which was Brill.

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Re: Playing with mercury

Post by basementer » Fri Jun 10, 2022 4:56 pm

Trinucleus wrote:
Fri Jun 10, 2022 3:15 pm
I used to have a (sealed) maze where you had to manouevre a globule of mercury into the centre which was Brill.
I had one. Clear plastic top and blue base? Mine originally belonged to my father, which probably dates it to the 1940s.
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Re: Playing with mercury

Post by Brightonian » Fri Jun 10, 2022 7:03 pm

basementer wrote:
Fri Jun 10, 2022 4:56 pm
Trinucleus wrote:
Fri Jun 10, 2022 3:15 pm
I used to have a (sealed) maze where you had to manouevre a globule of mercury into the centre which was Brill.
I had one. Clear plastic top and blue base? Mine originally belonged to my father, which probably dates it to the 1940s.
I had one too, I think this one, where I'd try to subdivide the mercury. I remember small bits of mercury would stick in corners.

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Re: Playing with mercury

Post by Boustrophedon » Fri Jun 10, 2022 7:12 pm

You are not allowed to own mercury now.

https://www.gov.uk/government/publicati ... n#fulllist
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Re: Playing with mercury

Post by Trinucleus » Fri Jun 10, 2022 7:46 pm

Brightonian wrote:
Fri Jun 10, 2022 7:03 pm
basementer wrote:
Fri Jun 10, 2022 4:56 pm
Trinucleus wrote:
Fri Jun 10, 2022 3:15 pm
I used to have a (sealed) maze where you had to manouevre a globule of mercury into the centre which was Brill.
I had one. Clear plastic top and blue base? Mine originally belonged to my father, which probably dates it to the 1940s.
I had one too, I think this one, where I'd try to subdivide the mercury. I remember small bits of mercury would stick in corners.
Yes, that one!

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Re: Playing with mercury

Post by Trinucleus » Fri Jun 10, 2022 7:47 pm

Boustrophedon wrote:
Fri Jun 10, 2022 7:12 pm
You are not allowed to own mercury now.

https://www.gov.uk/government/publicati ... n#fulllist
Boooo

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