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.

A demonstrator gestures during protests around the Argentine Parliament in Buenos Aires, Argentina, 10 March 2022. Serious disturbances were registered in the surroundings of the seat of the Argentine Parliament when demonstrators protesting against the new agreement with the International Monetary Fund (IMF) clashed with the police of the city of Buenos Aires. (Photo by Juan Ignacio Roncoroni/EPA/EFE)

The Soyuz 2.1b rocket with a Fregat-M booster and meteorology and emergency communications satellite Arktika-M No 1 launches from Baikonur Cosmodrome in Baikonur, Kazakhstan on February 28, 2021. Arktika-M No 1 is the first of ten Arktika satellites to be launched by Roscosmos into orbit. (Photo by Roscomos/TASS)

Star of Cabaret, English actor Eddie Redmayne attends The Olivier Awards 2022 with MasterCard at the Royal Albert Hall on April 10, 2022 in London, England. (Photo by David Levene/The Guardian)

A model poses for a photographer backstage ahead of the Ferreira Couture catwalk show at Malta Fashion Week in Valletta, Malta on July 20, 2022. (Photo by Darrin Zammit Lupi/Reuters)

British model Kate Moss attends the Saint Laurent Womenswear Spring/Summer 2023 show as part of Paris Fashion Week on September 27, 2022 in Paris, France. (Photo by Pascal Le Segretain/Getty Images)

U.S. Air Force Major Paul “Loco” Lopez performs in an F-22 Raptor during the AirPower Over Hampton Roads JBLE Air and Space Expo at Joint Base Langley-Eustis, Virginia, U.S. May 18, 2018. (Photo by U.S. Air Force/Staff Sgt. Areca T. Bell/Handout via Reuters)

Alejandro Ccasa prays after waiting three days next to an empty oxygen tank for his uncle who has COVID-19 outside a refill shop where he is the first in line before it opens in Callao, Peru, early Tuesday, February 2, 2021. Ccasa said his family has one large tank and it gives about four hours of oxygen therapy. (Photo by Martin Mejia/AP Photo)