John S wrote:
Elmer wrote:
This lucrative contract was awarded to Honeywell, a company known for
those ubiquitous, round thermostats containing toxic mercury,

Just about every thermostat manufactured by anyone contained mercury. (The
alternative was bimetallic strips which are nowhere near as precise, and
today digital thermostats have become popular.) But how is that relevant
here?


The mercury in thermostats was not used for temperature sensing. The
"classic" Honeywell thermostats used a bimetallic strip curled into a
coil. The two different metals in the strip expand and contract in
response to temperature changes at different rates from each other,
causing a rotation of the coil.

Attached to the coil is a small, sealed glass bulb with two contacts at
one end. There's a small ball of liquid mercury in the glass bulb which
closes the circuit between the contacts when it is tipped towards that
direction. The rotation of the coil happens very slowly as the
temperature changes, but once it reaches a certain point, gravity
causes the mercury to roll to the opposite end of the glass bulb all at
once. This achieves a quick on-off transition that minimizes arcing or
bouncing.

The set point was adjusted by simply rotating the bimetallic coil so
that the transition occured at a different temperature. It was an
elegantly simple, very reliable design which became the industry
standard for residental and commercial use for many years. The
environmental dangers of mercury have become more apparent in recent
times. In service, they pose no hazard, but items like this must be
recycled in a mercury specific program, and not disposed of into
regular trash.

Alternatives to using mercury in thermostats involved some other
mechanical design that would provide a "snap-action" transition from on
to off at the desired temperature. Mercury was only appropriate for low
voltage, low current switching. Any line voltage thermostat would use a
mechanical contact closure. An alternative to using bimetallic strips
is a gas filled bellows which expands and contracts in response to
temperature changes.

Other companies besides Honeywell used mercury in their thermostats in
both bimetallic and gas bellows designs, but the mercury was still only
used for switching, and not for temperature sensing. Today, solid state
temperature sensors have made bimetallic and gas bellows designs
obsolete, and other electronic components perform the switching
function instead of mercury.

My reason for mentioning Honeywell thermostats in the first place was
because they're a very common household product that almost everyone's
familiar with. It was an excellent product for it's day (although that
was fifty years ago).

Elmer

Elmer wrote:

The
environmental dangers of mercury have become more apparent in recent
times.

Haven't the dangers or mercury been known for a long time? There is the
Mad Hatter in Alice in Wonderland. Hatters were mad because they were
exposed to mercury vapor in making hats and suffered neurological damage.

John Mara

John Mara wrote:
Elmer wrote:

The
environmental dangers of mercury have become more apparent in recent
times.

Haven't the dangers or mercury been known for a long time? There is the
Mad Hatter in Alice in Wonderland. Hatters were mad because they were
exposed to mercury vapor in making hats and suffered neurological damage.

John Mara

The direct exposure to mercury, yes. But people did not think about
what happened when products containing mercury were thrown in the
trash. Mercury pollution from landfills and incinerators is now known
to be a significant problem and only recently have mercury specific
recycling programs been implemented.

Elmer

On 15 Jul 2006 18:07:34 -0700, "Elmer" wrote:


John Mara wrote:
Elmer wrote:

The
environmental dangers of mercury have become more apparent in recent
times.

Haven't the dangers or mercury been known for a long time? There is the
Mad Hatter in Alice in Wonderland. Hatters were mad because they were
exposed to mercury vapor in making hats and suffered neurological damage.

John Mara

The direct exposure to mercury, yes. But people did not think about
what happened when products containing mercury were thrown in the
trash. Mercury pollution from landfills and incinerators is now known
to be a significant problem and only recently have mercury specific
recycling programs been implemented.

My father used mercury when making fillings for teeth. I think I
expressed interest, or maybe he knew it would be interesting, so he
gave me maybe 4 cubic centimeters of it when I was 6, but I have to
admit, I've never found a use for it (except watching it). I think I
got another 4cc when he died 2 years later. I'm 59 now, and have
moved about 6 times, but the mercury has only had to move 4 times in
all these years. I keep saving it for a special occasion. Like
repairing mercury switches, but it was easier to buy another switch,
or use the ones built into car trunk and hood lights.

Elmer

"mm" wrote in message

My father used mercury when making fillings for teeth. I think I
expressed interest, or maybe he knew it would be interesting, so he
gave me maybe 4 cubic centimeters of it when I was 6, but I have to
admit, I've never found a use for it (except watching it). I think I
got another 4cc when he died 2 years later. I'm 59 now, and have
moved about 6 times, but the mercury has only had to move 4 times in
all these years. I keep saving it for a special occasion. Like
repairing mercury switches, but it was easier to buy another switch,
or use the ones built into car trunk and hood lights.

Elmer


Take it to any big building you want to shut down. Like a school or
government office. Drop it on the floor and start yelling Mercury, Mercury!

Al

mm wrote:
My father used mercury when making fillings for teeth. I think I
expressed interest, or maybe he knew it would be interesting, so he
gave me maybe 4 cubic centimeters of it when I was 6, but I have to
admit, I've never found a use for it (except watching it). I think I
got another 4cc when he died 2 years later. I'm 59 now, and have
moved about 6 times, but the mercury has only had to move 4 times in
all these years. I keep saving it for a special occasion. Like
repairing mercury switches, but it was easier to buy another switch,
or use the ones built into car trunk and hood lights.


Is this one of those "Who am I?" riddle questions? It sounds like one
of those puzzlers from the "Car Talk" guys radio program.

Elmer

On 16 Jul 2006 00:11:12 -0700, "Elmer" wrote:


mm wrote:
My father used mercury when making fillings for teeth. I think I
expressed interest, or maybe he knew it would be interesting, so he
gave me maybe 4 cubic centimeters of it when I was 6, but I have to
admit, I've never found a use for it (except watching it). I think I
got another 4cc when he died 2 years later. I'm 59 now, and have
moved about 6 times, but the mercury has only had to move 4 times in
all these years. I keep saving it for a special occasion. Like
repairing mercury switches, but it was easier to buy another switch,
or use the ones built into car trunk and hood lights.


Is this one of those "Who am I?" riddle questions? It sounds like one
of those puzzlers from the "Car Talk" guys radio program.

You know you're right. I just left out the question, how do you get
the car running again?

Big Al's plan is good, too.

Elmer

mm wrote:
On 16 Jul 2006 00:11:12 -0700, "Elmer" wrote:


mm wrote:
My father used mercury when making fillings for teeth. I think I
expressed interest, or maybe he knew it would be interesting, so he
gave me maybe 4 cubic centimeters of it when I was 6, but I have to
admit, I've never found a use for it (except watching it). I think I
got another 4cc when he died 2 years later. I'm 59 now, and have
moved about 6 times, but the mercury has only had to move 4 times in
all these years. I keep saving it for a special occasion. Like
repairing mercury switches, but it was easier to buy another switch,
or use the ones built into car trunk and hood lights.


Is this one of those "Who am I?" riddle questions? It sounds like one
of those puzzlers from the "Car Talk" guys radio program.

You know you're right. I just left out the question, how do you get
the car running again?


I bet it involves chewing gum, huh? ... I know! Use the chewing gum (it
can't be Freedent) to pull a filling out of your mouth. Because it
conducts electricity, the filling can be used to make a fuseable link
by smashing the trunk/hood down on it a few times.The filling gets the
car, (which I would expect to be something like a Mercury Monarch?),
started again, so it can be driven to the nearest dental office for
permanent repairs.

Am I close?

Elmer

mm wrote:
My father used mercury when making fillings for teeth. I think I
expressed interest, or maybe he knew it would be interesting, so he
gave me maybe 4 cubic centimeters of it when I was 6, but I have to
admit, I've never found a use for it (except watching it). I think I
got another 4cc when he died 2 years later.

We used to rub it on pennies to make them "silver". Entertaining for a 6 to
10 year old. We played with it a lot and I'm not brane ded or even sic frum
it.

On 16 Jul 2006 15:05:35 -0700, "Elmer" wrote:


mm wrote:
On 16 Jul 2006 00:11:12 -0700, "Elmer" wrote:


mm wrote:
My father used mercury when making fillings for teeth. I think I
expressed interest, or maybe he knew it would be interesting, so he
gave me maybe 4 cubic centimeters of it when I was 6, but I have to
admit, I've never found a use for it (except watching it). I think I
got another 4cc when he died 2 years later. I'm 59 now, and have
moved about 6 times, but the mercury has only had to move 4 times in
all these years. I keep saving it for a special occasion. Like
repairing mercury switches, but it was easier to buy another switch,
or use the ones built into car trunk and hood lights.


Is this one of those "Who am I?" riddle questions? It sounds like one
of those puzzlers from the "Car Talk" guys radio program.

You know you're right. I just left out the question, how do you get
the car running again?


I bet it involves chewing gum, huh? ... I know! Use the chewing gum (it
can't be Freedent) to pull a filling out of your mouth. Because it
conducts electricity, the filling can be used to make a fuseable link
by smashing the trunk/hood down on it a few times.The filling gets the
car, (which I would expect to be something like a Mercury Monarch?),
started again, so it can be driven to the nearest dental office for
permanent repairs.

Am I close?

Close? Except for it being a Chevy Malibu, you were exactly right.

Elmer

Edwin Pawlowski wrote:
mm wrote:
My father used mercury when making fillings for teeth. I think I
expressed interest, or maybe he knew it would be interesting, so he
gave me maybe 4 cubic centimeters of it when I was 6, but I have to
admit, I've never found a use for it (except watching it). I think I
got another 4cc when he died 2 years later.

We used to rub it on pennies to make them "silver". Entertaining for a 6 to
10 year old. We played with it a lot and I'm not brane ded or even sic frum
it.

And now your permanently 11 years old? ;-p