Mercury splits in my thermometer(s)?

Question

I have never managed to keep a thermometer more than a few months. After even a slight shock, the top of the mercury column splits and the reading loses accuracy. Is there any way to get the mercury back in one piece? Heat it up to the maximum? (but not too far past it...) or cool it down to the minimum? Any thought anyone? Many thanks

Answer 1

It's definately a mercury thermometer yeh-like the last answer said put it in the freezer (-18 if you can) the mercury will contract into the bulb-the last drop may need a little gentle tapping with your fingers to get it to run into the bulb. If you heat the thermometer the mercury will evaporate slightly and the gap will expand rather than disappear and when it cools again will return to the original and you'l just risk breaking the thermometer

Answer 2

It's not true that mercury thermometers have been banned, i suppose due to their accuracy when compared to spirit versions - they can even still be used in schools, though some local authorities may have banned them. Biggest problem is if they are banned you will then have to dispose of them!
I have in the past sorted this problem by heating in an oil bath to get the mercury column to extend into the expansion bulb at the top of the thermometer or cooling in an acetone/ dry ice mixture
Store vertically whenever possible to help avoid the problem - which does occur in spirit thermometers too.
How would you deal with this in a max/min thermometer with mercury and spirit in th column?

Answer 3

I've had this problem and found that heating the bulb very slowly and gradually until the mercury reaches the small bulb at the top and the 'split' disappears .. it will do the trick.
Allow the thermometer to cool down slowly too.

Answer 4

Shake the thermometer. Mercury is a liquid, so it can't "crack". If that doesn't work, put it in the freezer (it won't be cold enough to freeze the mercury, but it will make the mercury contract). Don't overheat the thermometer; mercury is hideously poisonous, and you don't want to force any out of the glass tube.

If you have an unuseable thermometer, bring it to a toxic collection centre.

Answer 5

I could be wrong? but I was under the impression that all Hg in glass thermometers had been banned.
(If they haven't then they should be)
I can only assume that the answers you have been given so far are suggesting that you empty your freezer of all food stuffs while you set the temp to below -18?
What a load of hassle, the Mercury thermometer must be really expensive if it hasn't been banned!
Just type into your search engine 'temperature measuring instruments' and search, there are so many different ways to cover all temperature range measurements without Hg and if you are getting through them at your rate, it must work out cheaper in the long run.

Answer 6

Depending on the temperature range, it is best if you can reduce the temperature sufficiently to get all the mercury back into the bulb. If the thermometer goes to very low temperatures, and you can't get dry ice or liquid nitrogen, heating can work, but it is risky.