Nature Chemistry | The Sceptical Chymist

ACS: Pressurized preservation

So, here I am in Washington DC for the fall 2009 meeting of the ACS. This is my first time in DC, so I arrived a day early to fit some touristy activities into my schedule – first stop a photo of The White House from as close as I could get (which in case you didn’t know is a long way away…).

I then went to see the Declaration of Independence, the Constitution and the Bill of Rights at the National Archives – and here’s a chemistry fact for you – they’re kept under pressurized helium. Now these are very important documents, and I’m not surprised to find that an inert atmosphere is used, but I did wonder about why helium was used instead of argon? Argon would probably be the synthetic chemist’s choice for an inert gas, particularly as it’s density makes it easier to work with, and as far as I know it’s cheaper as well.

My final stop yesterday was the Smithsonian museum of American History. Being a bit of a science geek, I was surprised to find and immediately headed for the Science in American Life exhibit which is currently running – so if you have a gap in your schedule or, dare I say it, are sloping off from the sessions at the ACS, I can highly recommend it.


Stephen Davey (Associate Editor, Nature Chemistry)


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    Michelle Francl said:

    I found out why helium was used – it has to do with its thermal conductivity relative to air and the way leaks were detected in the 1950s when the cases were designed. (I wrote a squib on Culture of Chemistry about it.)