How to Foil Nazis

The Nazis have just invaded your country and your life is in danger because you have two Nobel prizes you are safeguarding for friends — one is Jewish and the other is an opponent of National Socialism.  What do you do?

That was the dilemma faced by Niels Bohr in 1940 when Germany occupied Copenhagen, Denmark. The medals were made of gold, which could not be taken out of the country.  Chemically gold doesn’t tarnish, doesn’t mix, and doesn’t dissolve in anything — except for one special acid solution called  “aqua regia”, and even that takes time.

But that seemed the best solution.  How well did it work?  The entire story is at

(If you’re impatient, it worked very well.)

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