I was reading an article about wall switches and came across a mention of
how they used to be constructed of mercury. The article went on to say that
aside from the obvious problems associated with mercury, the switches
themselves were superior in action, quiet, longest lasting and most energy
efficient. It kind of begs the question to me - do any of you all still
have mercury switches in your house and if so - are they all that wonderful?
came across a few today still working fine in an apt. the only time i
seem to replace them is when asked to do so.as far as better probabaly
seeing things made today are not made to last, no money if your not
periodically replacing them.
Back in the 50's we had some in our house. They were silent and smooth
operating. Most switches today are pretty quite, but back then, the normal
switch made a pretty loud click. Back then, yes, they were all that
wonderful. Today, even a cheap switch performs well, is easy to flip, and is
I also recall having a bottle of mercury in the house. We used to play with
it and make shiny pennies. Today, we'd be tossed in jail for that and the
street would be evacuated. We also put Mercurochrome on cuts to help them
Exactly. In comparison to the big click, which could probably wake
most people who were sleeping, they were great. I think they were the
difference between middle class and upper middle class. (Expecially
if you had to hire an electrician to put them in.)
Did you ever get merthiolate? Which one stung and which one didn't?
There are four of them in the thermostat for my heat pump. According to
the inspector who inspected the house before I bought it, my heat pump
appears to be from around 1977, which is before mercury started being
phased out of homes, I believe.
Wikipedia has this to say about mercury switches in thermostats:
Mercury switches were commonly used in bimetal thermostats. The
weight of the movable mercury drop provided some hysteresis by
moving the bimetal spring slightly beyond the point it would
normally assume, thereby holding the thermostat off slightly longer
before flipping to the on state and then holding the thermostat on
slightly longer before flipping back to the off state. The mercury
also provided a very positive on/off switching action and could
withstand millions of cycles without degradation of the contacts.
I used to have a small vial of mercury, which I obtained sometime in the
early '70s, when I was around 12. Me and the other kids would take it
out now and then and watch it roll around and poke it with things. In
the vial, I kept a screw, which floated on top of the mercury. It was
It's funny to think that what we considered a toy back then and showed
our friends in school would probably prompt an evacuation if a kid
brought it to school today.
I don't know what happened to it. I think I lost it during a move.
they were mainly used because they were silent. Thermostats still use them
if they're not electronic. The only drawback on a standard spst mercury
switch is that it HAS to be mounted in the standard fashion only.
Can't be horizontal or on a horizontal surface.
"Eigenvector" <m44 email@example.com> wrote in message
I'm sure they are totally efficient, but how inefficient are the other
switches? Unles they are getting warm, even if you can't feel the
didfference, I think they are also totally effficient.
I'm sure at the end of their life they get warm, but mine are all 28
years old and as good as new afaict.
I have mercury switches in my car, to turn on the trunk light and the
dome light, and I've used them for burglar alarm switches in cars
also. But none of them get used mcuh.
I have loads of mercury, 10 or 20 cc, half that my father, a dentist,
gave me when he was alive and I was 6 or 7, and about an equal amount
that I guess I inherited after he died. His nurse, Grace, must have
remembered that I would want it**. It's been 52 years, and I've been
saving it for something special. The last 10 years I've lowered my
standards and would use it for something not special, but nothing has
come to mind.
Don't worry. I haven't poisoned myself. Playing with it was no fun
and only made it dirty for no purpose. I think I knew that at age 8
without even trying.
**I also got a whole bunch of cheap, plastic, hollow, small, cars and
buses, that he would give to kids after their dental work, but even at
the age of 8, I didn't want that stuff. I would have been happy to
get one piece after a dental visit, but getting 40 pieces, well, I
would rather play with my brother's Lionel train than with hollow cars
and buses. There was a third thing in that box too, that was only
slightly interesting at the time, but I don't remember what it was.
They work forever. But no bells and whistles, like auto setback.
I have them in 2 houses. I don't see any reason they'd be more
energy efficient than any other thermostat, and they are certainly
less efficient than a modern auto setback unit.
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