During World War II, Nazi soldiers were searching for Niels Bohr, a Danish scientist who had helped two German physicists escape. The Gestapo believed that the two Nobel Prizes left behind by the physicists would serve as evidence against Bohr, potentially leading to his execution.
To hide the solid gold prizes, chemist George de Hevesy suggested using aqua regia, a solution that could dissolve gold. Hevesy dissolved the gold and placed the solution on a high shelf among other chemicals. When the Nazis ransacked the building, they failed to find any trace of gold, unaware that it had been cleverly concealed in plain sight.
After the war, Hevesy reversed the process, extracted the gold, and returned it to the rightful owners. This remarkable feat not only saved Bohr’s life but also demonstrated the power of aqua regia and its ability to fool the Nazis.
In April 1940, early in the Second World War, Nazi Germany invaded and occupied Denmark.[97] To prevent the Germans from discovering Max von Laue’s and James Franck’s gold Nobel medals, Bohr had de Hevesy dissolve them in aqua regia. In this form, they were stored on a shelf at the Institute until after the war, when the gold was precipitated and the medals re-struck by the Nobel Foundation.