If we were to burn NH4Cr2O7 with HgSCN in the Dark Ages in Europe and show it to anyone, it is us who would be burning next on a fiery cross of Inquisition. And it’s no wonder, since this experiment produces a truly marvelous result. At first, as you ignite the mixture of NH4Cr2O7 and HgSCN, all you can see is that it is slowly burning with a reddish flame. After a while, however, a crater is formed in the middle of the burning pile, and then, suddenly, tentacle-like appendages start sprouting from the burning mixture. And you can almost hear the scream of the mad occultist – “Come forth, Kraken! Come forth!” But of course, this is simply a chemical reaction that is called the "Pharoah's Serpent". It was also often sold in firework stores until people realized that it was toxic.

In this June 16, 2015 photo, an Indian coachman sleeps on his Victoria horse-drawn carriage outside a stable in Mumbai, India. Drivers of Mumbai's iconic horse-drawn carriages can't imagine not plying the roads pulling photo-snapping tourists atop their kitsch-covered chariots. Yet that time is coming, thanks to a court order calling such superfluous “joyrides” a form of animal cruelty and banning them in India's financial capital from June 2016. (Photo by Rafiq Maqbool/AP Photo)

Young adults wearing a mask, attends a ceremony as they commemorates the Coming of Age Day of young people entering adulthood in Tokyo, Japan, on January 10, 2022. While the COVID-19 epidemic continues to progress in Japan due to the new Omicron variant, the events that have been organized by the various municipalities of Tokyo have followed a strict sanitary protocol, such as temperature control, disinfection of hands, and the wearing of a protective mask. (Photo by David Mareuil/Anadolu Agency via Getty Images)

Rocky the cat's recovery from a nerve condition in his legs is coming along swimmingly – thanks to regular hydrotherapy sessions at a 20ft-long swimming pool in United Kingdom in the second decade of March 2022. The two-year-old wears a life vest to help keep him afloat and needs a plastic toy to lure him from one end of the pool to the other. (Photo by Max Willcock/BNPS Press Agency)

Members of the NYPD detain protesters from the pro-Palestinian protest encampment and Hamilton Hall where demonstrators barricaded themselves inside on April 30, 2024 in New York City. Police arrested nearly 100 people as they cleared the university of demonstrators who were issued a notice to disband their encampment after negotiations failed to come to a resolution. University President Minouche Shafik has requested the NYPD maintain a presence on campus through at least May 17.(Photo by Stephanie Keith/Getty Images)

The picture dated February 24, 2025 shows Squadron Leader Nathan Sawyer, the RAF Typhoon display pilot for the 2025 season, practising over RAF Coningsby in Lincolnshire ahead of this year's airshows. Wisps of rainbow vapour were seen coming out of the tail as he put the plane through its paces at 1500ft. (Photo by Claire Hartley/Bav Media)

A man holds a tree branch and marches by burning tires during a protest against insecurity, on August 7, 2023, near the Prime Minister's official house in Port-au-Prince, Haiti. Some 300 women and minors were kidnapped in Haiti by criminal gangs in the first half of this year, UNICEF said Monday, warning of a disturbing rise in abductions that leave “deep physical and psychological scars”. The surge in abductions threatens “both the people of Haiti and those who have come to help”. (Photo by Richard Pierrin/AFP Photo)