Elements: Silver

20 June 2012

The second in our series of Elements films is silver (the first was tin, which you can read more about in yesterday’s blog post). In the video above, Andrea Sella talks about what is behind silver’s tendency to tarnish and how you can restore it to its natural brilliance with a simple trick.

It’s not in the video, but Andrea also told me about his prized Dewar flask (see the picture). Andrea has an interest in glassware and its history, and this is his favourite piece. Towards the end of the 19th century, physicists were working on liquifying air and needed some means of storing this very cold liquid for long periods. This container would require really good insulation. James Dewar, who was working at the Royal Institution, came up with the solution that would become known as a Dewar flask.

 Andrea Sella with a silver lined dewar flask
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Andrea Sella with a silver-lined Dewar flask

The flask has an inner and outer ‘shell’ of glass, which have a vacuum between them that ensures that energy can’t be easily transmitted from the inside to the outside of the flask. But Dewar also used a technique that created a very thin layer of silver on the inside of the glass. It’s this that gives it the beautiful reflectiveness which helps to keep heat out. It is, as Andrea says, perfect double glazing.

You can see the full playlist of Elements films, including last year’s, on this YouTube playlist. For more information about the event, which is happening this Friday (22 June) from 19.00 to 23.00 at Wellcome Collection, see here.