Scientists from the University of Bristol have uncovered the mystery behind the appearance of purple smoke from the explosion of gold fulminate, the first known explosive in history. This solution sheds light on a 400-year-old alchemical mystery. Their research paper was published on the preprint server arXiv.

Discovered by alchemists in the 16th century, gold fulminate is a mixture of various compounds, with ammonia playing a key role in the substance’s explosive power.

German alchemist Sebald Schwarzer in 1585 noticed unusual purple smoke from the explosion of gold fulminate. This material was later studied by great chemists of the 17th and 18th centuries, including Robert Hooke And Antoine Lavoisier.

Although the recipe for gold fulminate has been known for centuries, the question of why purple smoke is produced when it explodes remains an open question.

It had long been assumed, but not proven, that the intense purple color of the cloud was due to the presence of gold nanoparticles. Now Professor Simon Hall’s team from the University of Bristol has changed that.

“I’m pleased that our team was able to answer this question and improve our understanding of this material,” said Professor Hall.

“Our experiment was to create gold fulminate, then we detonated 5 mg of samples on aluminum foil, heating it. We captured the smoke using copper grids and then analyzed the sample under a transmission electron microscope. We found spherical gold nanoparticles in the smoke, thereby confirming the theory about the role of gold in the mysterious smoke,” explained Professor Hall.

Having solved one of the historical scientific mysteries, Professor Hall and his team plan to use this method to study the nature of clouds formed by other explosive metals such as platinum, silver, lead and mercury, about which many unresolved mysteries remain.