It has been a scientific mystery which has baffled chemists for almost 450 years - but now the question of why the first high explosive ever discovered produced a purple smoke has finally been solved - by academics from Bristol.
Back in the 1580s, early chemists discovered fulminating gold, a mixture of a number of different compounds which under the right conditions violently exploded. It was the first high explosive ever discovered, sparked a huge rush to alchemy with scientists for centuries trying to discover how to turn base metals into gold, but the chemical interaction, and the reason why, when it exploded, it created an incredible and distinctive purple-coloured smoke have always been one of science’s great unknowns.
That is, until scientists at the University of Bristol decided to see if they could achieve what centuries of the world’s greatest chemists couldn’t, and work out why fulminating gold exploded with a purple smoke. By its very nature, it’s a dangerous job, but they managed it.
The chemistry of the fulminating gold recipe has been understood for centuries, but one question remained unanswered, said a spokesperson for the University of Bristol - why does its detonation produce purple smoke? “It has long been supposed, yet previously never proven, that the rich purple colour of this cloud was due to it being formed of gold nanoparticles,” he said. “This has now changed thanks to Professor Simon Hall, Professor of Chemistry at the University of Bristol and his PhD student Jan Maurycy Uszko.”
Fulminating gold was first discovered by alchemists in the 16th century, and back in 1585, the purple smoke was noted by German alchemist Sebald Schwaertzer. The leading figures of chemistry in the 17th and 18th century, including Robert Hooke and Antoine Lavoisier researched the question, but couldn’t find the answer. It took 21st century technology to work it out.
“I was delighted that our team have been able to help answer this question and further our understanding of this material,” Professor Hall said.
“Our experiment involved creating fulminating gold, then detonating 5mg samples on aluminium foil by heating it. We captured the smoke using copper meshes and then analysed the smoke sample under a transmission electron microscope,” Professor Hall explained.
“Sure enough, we found the smoke contained spherical gold nanoparticles, confirming the theory that the gold was playing a role in the mysterious smoke.”
Having solved one historic scientific puzzle, Professor Hall and his team plan to use this methodology to study the precise nature of clouds produced by other metal fulminates such as platinum, silver, lead and mercury, which remain an open question.