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  • Mercury

    Someday I want to make a clock with a temperature compensating pendulum. One way is to use a bob comprising two vials of mercury. My questions: Where can one buy mercury? Is special permission or qualifications required? How does one handle it safely? Is it just too dangerous and should I plan on another method? I haven't calculated how much I need, I'd guess 10 pounds or so.

  • #2
    A couple of kids around here just took a couple of ounces to school and spilled it in two classrooms. Cost to clean it up was $30,000.

    We used to roll it around in our hands and coat pennies when the thermometer broke, thought it was great fun.

    It may be possible to get it in quantity, but I wouldn't recommend it, the problems posed down the road could be substantial.
    Jim H.


    • #3
      Mercury is dangerous and certainly precaution should be taken about handling and storing it. Having said that, I think the dangers of it have been overrated especially in a pure form. Don't worry about breathing it in, since at room temperature it has extremely low vapour pressure. Soluability is also very low in most solvents so even the casual contact is not going to kill you. It becomes an occupational hazard if you have to deal with it daily since it's the cumulative effect which will eventually affect your health. In short, I'd far rather handle a bottle of mercury than a bottle of nitric acid.

      I definitely would not recommend using mercury for clock making, since this is something that would be left exposed in a living area. Have you though about using Invar metal for temperature compensation?



      • #4

        Make up a reasonable sounding company name and you can order open-account.

        These guys are easy, not cheap.

        Be careful, regards,



        • #5
          There is a much better way to do it by using a compound sort of suspension using metals of different coefficients of expansion. One of the Village Press mags recently had a series on doing this, I don't remember which one, but a search of the index should turn it up. As I recall, the author used steel and aluminum rods to get his compnesation.


          • #6
            Mercury has such a large molecule it is very difficult to pass through human membranes. One doctor I heard stated you could eat it and it wouldn't enter the bloodstream through the stomach lining and you would just pass it out, someday.

            The environmentalists hate it but they have been mind melded with a rockchuck. I did the same thing with pennies way long time ago and I used to pop open the vials on mercury switches to keep my supply up.

            It is used to amalgamate with gold so you can get the last bit then fired off. You get the mercury back and the gold seperated out. Used in South America all the time.

            I used to use it in manometers to balance carbs on autos and bikes but if you sucked any through into the combustion chamber and subjected it to internal combustion you were in a ton of trouble.


            Having said that, My advice is to leave it alone and use someothere compensation device.

            GreenWillyPeter at your service.

            Some things are here just to mess you up. The hard part is to get someone else to do the messing.


            • #7
              regarding mercury for clock pendulums, Empire Clock Co sold it in sealed glass vials for making small pendulums like on French clocks and some American "kitchen/walnut clocks", otherwise you do have to scrounge to from thermometers, mercury switches, blood pressure gages and the like. But use caution.
              I can remember doing lots of stuff with it when I was a kid too.


              • #8
                Seems like we all did this when we were kids, wonder if this is why we think funny and forget something sometimes.......... where was I
                mark costello-Low speed steel


                • #9
                  The warning about mercury vapor is the real key to its hazard in the home or other buildings. At normal room temps it is not a problem, but dropped on the floor as happens sooner or later, it doesn't take very much of it rolling near or under the heating system for the vapor to make the air decidedly unhealthy. So treat it with respect when it is the ONLY way to get a job done, and find alternatives whenever you can.

                  Rich Kuzmack

                  Pi = 355/113 . . . to
                  <85 parts per billion
                  Rich Kuzmack

                  Pi = 355/113 . . . to less
                  than 85 parts per billion!


                  • #10
                    I would avoid it.
                    I have seen the use of different metals for compensation, as I recall zinc was one. I can look it up in my clockmaking book.

                    If you spill mercury, I was told by a chemist relative that the best thing is to dump sulfur on what you can't scoop up.
                    Siezes it as a sulfur compound , and holds it securely while you sweep it up.

                    It is a serious problem, remember "Minimata disease"? caused by eating fish with high mercury content, as I recall. Very bad, serious nerve damage and paralysis, a sort of chemically induced Parkinsons + Alzheimers disease.


                    • #11
                      There is a movement to eliminate the use of Mercury in all but absolutely essential (scientific use only) circumstances. Medical use (thermometers & blood pressure cuffs) is being phased out due to toxicity concerns.
                      Some commonly used metals are also very toxic. Cadnium plated fasteners require gloves or proper wash up after handling.

                      Beryllium is very toxic to handle or use - it should never be machined or ground unless exceptional care is taken to prevent contamination - if you have any of the old set-up wedges made of this stuff put it in a baggie and drop off at a toxic disposal site.

                      Forget the Mercury, look for an alternative that is not as dangerous. The health of yourself and your loved ones is more important than nay benefits it may present.


                      • #12
                        Pure mercury does not exist as a molecule.

                        The part about the environmentalists is correct however (I assume a rockchuck is something disgusting...). They, along with altmed crackpots, are responsible for a lot of hysteria on the internet about mercury.

                        <font face="Verdana, Arial" size="2">Mercury has such a large molecule it is very difficult to pass through human membranes. One doctor I heard stated you could eat it and it wouldn't enter the bloodstream through the stomach lining and you would just pass it out, someday...The environmentalists hate it but they have been mind melded with a rockchuck.</font>


                        • #13
                          How about using invar.
                          A nickle iron developed by clock makers for just this expansion problem.
                          It's expansion rate is near zero.
                          Now used by NASA for brackets, and arms on telescopes in space.
                          Metal mite


                          • #14
                            Oso's right about the cleanup. I was a weatherman in the AF, and every weather station maintained a mecurial barometer that contained maybe a couple of quarts of mercury. We were required to also keep on hand a supply of 'Flowers of sulphur', just in case we had a spill. As a kid a friend's uncle used mercury batteries for his hearing aid. We'd crack them open and shine up our dimes, etc., and handle the stuff with abandon. I'm sure we ingested some too. That was about 50 yrs ago. I'm still here. (But then maybe there's something to that brain damage concern!)
                            Lynn (Huntsville, AL)


                            • #15
                              The issue with the start of the article about a compensated pendulum is the Sep./Oct 2000 issue of HSM.