Mercury ??

While cleaning up and sorting old parts, found these. To my best recollection they may be mercury switches from the first generation of 'silent switches' way back. Was hesitant to drill a hole in one of them. Something inside makes a small noise if you shake it but not really distinctive enough to confirm it is liquid. Anybody recognize these? Thanks.
 

GoldDigger

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The liquid inside is the only liquid at room temperature metal that is a sufficiently good electrical conductor, namely mercury. A similar looking capsule was also used in omni-directional tilt switches. The mercury switches in thermostats, AFAIK, all used glass capsules for the contacts.
 

LarryFine

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Henrico County, VA
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If you want to be sure, put it in the freezer for a few minutes, then shake it again and if you don't hear anything moving inside, it's mercury.
I haven't checked, but I believe mercury must be chilled much lower than a home freezer to solidify.
 

infinity

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When I was a kid my grandfather had a small glass jar that he would put in mercury that he removed from old thermostats, thermometers, relays, and gauges. Although it held only a few ounces it was very heavy. He called it quicksilver, I remember pouring a few drops on a work bench and watching it move as it was pushed around. It was very cool to play with. Back then no one ever mentioned that it was toxic.
 

mbrooke

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When I was a kid my grandfather had a small glass jar that he would put in mercury that he removed from old thermostats, thermometers, relays, and gauges. Although it held only a few ounces it was very heavy. He called it quicksilver, I remember pouring a few drops on a work bench and watching it move as it was pushed around. It was very cool to play with. Back then no one ever mentioned that it was toxic.

If you just touch it for a few seconds I doubt it was even mildly toxic happen. The real issue is leaving the jar open. Mercury evaporation doubles for every 10*F rise in temp, and it is absorbed through the lungs on orders of magnitude better than any other route including oral for elemental mercury.
 

Barbqranch

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Arcata, CA
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Plant maintenance electrician
But the mercury vapor pressure is very low at room temperature, so it isn't the high risk some people believe. If you left a small drop on the back shelf I'll bet that in 50 years you couldn't tell the difference, and could only weight it with precision scales.
Back in the day when they used it to separate gold, and then burned it off, that was a different story.
 
Thanks for the interest. I have collected lots of odd bits and parts over the years, that seemed interesting at the time. My pieces have a metal cap on both sides - the contacts - so can't see inside. Hg certainly does not get solid in a home freezer - would have not been much good as an outside thermometer that way. And tombs in China and Mexico reportedly have mercury used to simulate rivers, so it does not evaporate much at normal temperatures. They will get labeled and included in the next trip to hazardous waste disposal.
 

synchro

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Chicago, IL
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EE
When I was in third grade some kid brought in a mercury switch which he said that he got from the furnace at home :rolleyes:.
It was just like the one pictured below. We were all passing it between each other, and then there was a crash and the mercury spread out across the floor in many tiny droplets. The teacher's solution was to hand out index cards to the kids, and we all crouched down trying to round up all the little droplets and gather them to together into one big blob. I don't remember what happened then, but the teacher probably just tossed it into the local garbage pail and that was that.
mercoid-switch.jpg
Nowadays I'm sure they'd call in a hazmat team and close the whole school to do a remediation/cleanup.
 

PaulMmn

Senior Member
Location
Union, KY, USA
When I was in third grade some kid brought in a mercury switch which he said that he got from the furnace at home :rolleyes:.
It was just like the one pictured below. We were all passing it between each other, and then there was a crash and the mercury spread out across the floor in many tiny droplets. The teacher's solution was to hand out index cards to the kids, and we all crouched down trying to round up all the little droplets and gather them to together into one big blob. I don't remember what happened then, but the teacher probably just tossed it into the local garbage pail and that was that.

Nowadays I'm sure they'd call in a hazmat team and close the whole school to do a remediation/cleanup.
Growing up we dropped a thermometer at home. Did the same thing to corral the mercury. I'm sure there are cracks between the floorboards that still have mercury in them!
 

winnie

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Mercury spill in a home horror story of old tech, insufficient care taken, then crazy response:
 

Jraef

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Didn't think to look up the temperature issue, but of course it makes sense, otherwise you couldn't use a mercury thermometer on a freezer.

When I was a kid, we had a jar of mercury, maybe about 1/4 cup, left over from my grandfather having worked at mining gold in the 30s. We played with it a lot, including in our bare hands. I remembered it being frozen once but as I think of it again, I realize that freezer was from a bio-science lab that my father had bought out where they stored all kinds of super cold stuff that, if you touched it with bare skin, would essentially burn you (as we referred to it at the time). So I guess it must have been capable of -40F. My brother froze the mercury and hit it with a hammer, shattering it all across the garage floor. Then when all the little pieces liquified again and we collected them with an eye dropper. As I recall, my Dad was not ammused.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
But the mercury vapor pressure is very low at room temperature, so it isn't the high risk some people believe. If you left a small drop on the back shelf I'll bet that in 50 years you couldn't tell the difference, and could only weight it with precision scales.
Back in the day when they used it to separate gold, and then burned it off, that was a different story.
I had a property in Dahlonega, Ga. Quite a bit of mercury around there when they were mining gold. Even though the California gold rush is more well known, Georgia actually had better quality of gold. My property was walking distance to several mines. That’s when I started drinking bottled water instead of well water! The water around there had a lot of iron bacteria in it. About once a year, I would have to dump a gallon or so Clorox down the well, or the toilet bowels would turn orange.
 
I am pleased you all seemed to have fun with this. I was pretty sure I pulled these from old 'silent' switches somewhere in my past (owned an antique colonial once upon a time). Will send to the local hazardous waste facility.

As far as toxic substances go, mercury is relatively inert. I think you would either have to heat it up and vaporize it, or get it to combine with another chemical to make a water soluble compound, to get something more likely to be absorbed. As far as thermometers breaking, never heard of that happening, and my Mom was a nurse her entire career and used them all the time at home and at the hospital. But I guess it happens. Thanks again for the responses.
 
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