Removing mercury from 19th century stick barometer

Diane Fullick <fullick [at] verizon__net> writes

>I am a conservator in private practice and am submitting this query
>for a client who does not have access to the DistList. My client is
>the collections manager for a historic house museum which has a 19th
>century stick barometer mounted on a wall in the museum. One day the
>barometer was removed from the wall and placed flat on the floor and
>some of the mercury spilled onto the floor. An environmental clean
>up agency was called to deal with the spilled mercury, but they
>would not touch the object and only removed the mercury that had
>spilled.
>
>At the request of the director, the collections manager is exploring
>the option of emptying the barometer and disposing of the mercury to
>prevent future spills. ...

At the Canada Science and Technology Museum in Ottawa, we have a
fairly large collection of barometers. We store these upright, over
stainless steel trays, in case of future leaks. We do have one 19th
century barometer that is "open". It is referred to as a Banjo
barometer because of its shape, but the mechanism relies on an open
tube of mercury, a weight which rises as the mercury level does, a
string and a pulley. It's not as accurate as the sealed stick
barometers, but was relatively inexpensive to make at the time.

In cases where the mercury was leaking from stick barometers
(usually at the cistern seal at the bottom), I was able to repair
the seals by very slowly inverting the tube and resealing the
damaged areas. Those that proved irreparable, or where the glass was
broken, were emptied and the mercury disposed of according to
regulations. In the case of an open tube barometer in a historic
house, I would think that removing the mercury would be justified to
prevent just such another accident.

I did attempt to empty and replace the mercury in one stick
barometer, following the very comprehensive advice of an expert in
the UK, but after one almost disastrous attempt, decided against
pursuing that. The gentleman in question is Peter Hanson, at
info [at] quicksilver-barometers__co__uk. He was very helpful to me, and
could probably advise you further.

Sue Warren
Conservator
Canada Science and Technology Museum
1867 St. Laurent Blvd.
PO Box 9724
Ottawa Terminal
Ottawa, Ontario K1G 5A3


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                  Conservation DistList Instance 21:23
                Distributed: Sunday, September 23, 2007
                       Message Id: cdl-21-23-002
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