UPDATE: Nothing new under the sun. Woehler himself described this reaction back in the 19th century. As a pyrotechnic snake firework it is of course banned because it’s highly toxic. An explanation in an old ACS paper for what’s going on thanks to Stuart Cantrill.
Ever burned mercury(II) thiocyanate powder in a fish tank? This has to be the most skin-crawliest, creepy chemical decomposition reaction. Always knew the alchemists were on to something with their brews of mercury, sulfur and urine…well maybe not the urine…
Thanks to Chemistry World Features Editor Neil Withers for highlighting.