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. ...

We have a number of objects with mercury in our scientific
instrument collection. As a measure of precaution we remove all the
mercury that is not sealed. The vapour pressure of mercury is
extremely low and it can easily vaporise at room temperature
(0.00017 mbar at 20 deg. C.); mercury vapour is very toxic, much
more than liquid mercury (source: ROMPP Chemistry Dictionary).
Considering the health issues I wouldn't worry too much about the
integrity, especially when the barometer is going to be on open
display. You can always keep the mercury in a separate container
under safe conditions if you manage to collect it. To remove mercury
we use the "Aldrich - Mercury Absorption Kit".

About the construction (our Head of Collection gave the following
explanation): The glass tube is probably broken. Originally the tube
would have been sealed at the top in order to ensure the retention
of the vacuum and prevent it from filling up with air.

More information can be found at

    <URL:http://www.barometerworld.co.uk>

Angela Karsten
Objects Conservator
The Royal Institution of Great Britain
21 Albemarle Street
London W1S 4BS


                                  ***
                  Conservation DistList Instance 21:24
               Distributed: Saturday, September 29, 2007
                       Message Id: cdl-21-24-004
                                  ***