A Threat from Berlin
When Germany invaded Denmark in April 1940, Niels Bohr faced an unusual problem. Inside his Institute of Theoretical Physics in Copenhagen sat two gold Nobel Prize medals that did not belong to him. They had been entrusted to him by German physicists Max von Laue and James Franck, both banned from holding their awards under Nazi law.
If the occupying army found the medals, they would be confiscated. Worse, their owners might face severe punishment for defying the regime’s orders. Bohr had to find a way to make them vanish.
Banned Laureates
The story began years earlier. After jailed peace activist Carl von Ossietzky received the 1935 Nobel Peace Prize, Adolf Hitler forbade all Germans from accepting or keeping Nobel awards. Laue, who had won the 1914 Nobel Prize in Physics, and Franck, honored in 1925, secretly sent their 23-karat gold medals to Bohr’s institute for safekeeping. Both men had already felt the weight of Nazi restrictions.
Following the 1933 election that brought Hitler to power, new laws purged Jewish academics and their supporters. Franck resigned from Göttingen University in April 1933 despite an exemption due to his military service, and helped dismissed Jewish scientists find work abroad. Laue, dismissed from his advisory role at the Physikalisch-Technische Reichsanstalt, assisted Otto Hahn in secretly aiding persecuted colleagues to emigrate.
The Chemistry of Disappearance
When the Nazis entered Copenhagen, Bohr and Hungarian chemist George de Hevesy debated what to do with the medals. Simply hiding them seemed too risky. Instead, they turned to chemistry. They submerged the medals in aqua regia, a powerful mixture of nitric and hydrochloric acid known to dissolve gold.
The solid prizes melted into an orange solution, poured into a flask and left in plain sight on a laboratory shelf. German soldiers passed through the building without realizing that priceless Nobel medals were hidden in what looked like an unremarkable chemical sample.
Restoring the Gold
De Hevesy fled Denmark in 1943, leaving the flask behind. It remained untouched until after the war, when he returned and carefully precipitated the gold back out of the solution. The recovered gold was sent to the Nobel Foundation in Sweden. In 1952, newly cast medals were presented once more to Max von Laue and James Franck.
What had seemed lost to history was restored, thanks to quick thinking, chemistry, and the quiet bravery of scientists who refused to let the Nazis rewrite their story.
When Nazis invaded Denmark in 1940, Niels Bohr faced a secret danger: two Nobel medals of German physicists Max von Laue and James Franck.
If discovered, the gold would be seized and the men punished.
Bohr and chemist George de Hevesy had to make them disappear fast…🧵👇 pic.twitter.com/Ytf30AAZNh
— Fascinating True Stories (@FascinatingTrue) September 27, 2025