How to Remove Mercury Bubbles

[GT250]

Hi all,
Have obtained this - I think - old thermometer.
The Glass vial is about 950mm long.

There are gaps/bubbles in the Mercury (I'm assuming it's Mercury), and I was wondering if anyone here might suggest on how to remove them?

Any ideas on how old it is, because I'm pretty sure they don't "make 'em like they used to...."


Therm Long


Therm Make


Therm Bubbles


Therm Mercury Bowl


Therm Plate


Thanks Guys.

[lsemmens]

I'd try by flicking it like the nurses used to do. Possibly putting it in water and gradually heating it until the temp goes up to near the max might do it too.

[wotnot]

[VroomVroom]

what a find , almost looks like something found in a CSIRO lab in the 1940s lol

[WhiteOx]

I'd try by flicking it like the nurses used to do.

That might be rather difficult - did you see how long it is?
You'd have to swing it around like a bat.

[loopyloo]

That might be rather difficult - did you see how long it is?
You'd have to swing it around like a bat.

I had to read that twice. I first thought you said "cat". lol

[GT250]

Yes, what a great find VroomVroom. I love the old stuff!

Wotnot - Great find... I'll have a go over the weekend.

I was wondering if I can buy replacement Mercury - one assumes, it is Mercury in the tube?
Does Mercury 'go off'...?
It doesn't look crash hot...

BTW, if anybody wants it, please let me know. However, the P&P might be problem with the length... LOL!

But I'll do my best over the weekend to remove the bubbles...

Hey, once again guys, thank you for the replies. I really do appreciate them and it's all good to see something different come through and work out how to repair the old stuff...

If I get the bubbles out, should I replace the Mercury, or just leave it as is...?

Cheers,
GT250.

[lsemmens]

I don't think you'll be able to get replacement mercury, there is something in the back of my mind that says that mercury is no longer used because it's carcinogenic, or something like it. Just a quick search found this

Elemental or metallic mercury is a shiny, silver-white metal, historically referred to as quicksilver, and is liquid at room temperature. It is used in older thermometers, fluorescent light bulbs and some electrical switches. When dropped, elemental mercury breaks into smaller droplets which can go through small cracks or become strongly attached to certain materials. At room temperature, exposed elemental mercury can evaporate to become an invisible, odorless toxic vapor. If heated, it is a colorless, odorless gas. and about the .
Elemental mercury is an element that has not reacted with another substance. When mercury reacts with another substance, it forms a compound, such as inorganic mercury salts or methylmercury.

From >>>>>>

[wotnot]

Wotnot - Great find... I'll have a go over the weekend.

I was wondering if I can buy replacement Mercury - one assumes, it is Mercury in the tube?
Does Mercury 'go off'...?
It doesn't look crash hot...

.

I recognized it as a barometer straight away ~ we had one like it in our highschool science lab... If you click on the link in that article, you get the old school illustration =)

Mercury doesn't go off as such, it just gets contaminated with oxides and crap ~ as there's air bubbles (which may contain water vapor) in the column, there's a good chance the inside of the glass tube is also dirty, so be aware of that.

There's a number of ways to 'clean dirty mercury' (search that string to see), but back in highschool days we were taught this -->

To be doing a proper job of it, you'd have to remove all the mercury, and clean it and the glass tube, reassemble and then recalibrate it.

[trash]

It's a Barometer GT. I'm horrified at suggestions about how to restore it.

Tapping it, shaking it and turning it upside down. YOU PEOPLE ARE BARBARIANS!
Bring it down here and I'll put it in a vacuum chamber and pump it down. I'll even let you watch it repair itself using white man magic

It's a really nice barometer. Don't give it away. You know I'll give it a good home or swap you for for something you might like better.

[GT250]

Hi Trash,

BARBARIANS..!! That's gonna hurt some feelings Trash LOL!

A vacuum pump? Ok. I'll get it to you then Trash if you reckon you can fix it.

[trash]

I have a pump that will suck a bowling ball through 20ft of garden hose.
To repair the barometer doesn't require that hard a vacuum. I can get the mercury to within a mm of the bottom. Getting the mercury back in is harder.
I've got a big bottle of it for this kind of thing, Once it's loaded, the pressure has to be decreased slowly or it the mercury will shoot up through the glass like a bullet.

I'll see if we can make a video of what we do. With a bit of luck the chamber I have in mind is big enough and has a window.

[RFI-EMI-GUY]

Whatever you do, don't eat the mercury. It is not good for you.

You cannot legally ship that thing.

Interesting and frightening fact. If you ship it via airplane and the mercury leaks out into the plane, the plane is ruined. No kidding, those balls of mercury will corrode the aluminum of the plane and the wings will eventually fall off.


Sent from my SM-T350 using Tapatalk

[trash]

Ok, all done.

I had a vacuum chamber which was just big enough to fit it in. Unfortunately I wasn't able to get the angle right on it.
I could pump it down but wasn't able to get the air out of it. Even if I was able to get the air out I wasn't able to get the mercury back in.
I needed to be able to flip it over in the chamber. That just wasn't going to happen.

So I had to get creative. Do it all on the bench with just a pump and a hose. It took a few attempts yo get it right. The first was just to see if I could pump the air out. Most of it, but not the last 30mm which is the length of the neck. And it probably would work just fine like that but I prefer to get it right. So trying to pump out the air by getting the port below the mercury. It sounds easier than it is to do. The problem is the mercury can end up in the pump if you're not careful. When I got all the air out and let the mercury back in, there wasn't enough and so the air bubbles get back into the bottom of the tube. Argh, annoying.

So I pumped the air out again and the mercury and emptied it right out and cleaned the tube using the mercury.
Completely empty I loaded up the reservoir with mercury and then pumped the air out and let the mercury back in.
Doh, still not enough! So I had to repeat it all again and load up the reservoir and the hose. That was enough to fill the tube.

The only problem was it appeared to be a bit low, as if there was still some fraction of air that had leaked in. Again, this would be not really be a problem but I decided to start from scratch and make sure the vacuum was rock solid 1e-6 mBar before backfilling it with mercury and......... it was still low.
Low wasn't unexpected but it just seemed a lot lower than I expected. So I went and got a measure and some weather data and QHN and some altitude data and put it all together and the answer was 100% spot on.
So then all that I needed to do was calibrate it and set it up and give it a little bit of a cleanup. Done. It's pretty sweat.
I then used it to calibrate my mechanical baraometer which I noticed was off by about 8mBar.

Fire up the turbo molecular pump and bodgey up the connection with a piece of duct tape. If you can plug a hold in a Soyuz capsule with it, then it will hold back 14psi easy.


Then end result.

[GT250]

Well done Trash!
Was wondering how you were going to calibrate it with the height and knowing what the pressure was at the time you did it.

If anyone had some duct tape that seals up Soyuz capsules, it'd have to be you.....

Cheers,
GT250.