A protester runs from a jet of water shot from a police water cannon in the courtyard of the University of Santiago, during clashes between students and police, in Santiago, Chile, Thursday, May 14, 2015. In the capital and other cities across the country, high school and university students marched, for the second time this year, to demand education reform. (Photo by Luis Hidalgo/AP Photo)

Walking figures depicting late US rock and roll legend Elvis Presley appear on a traffic light switching from green to red in Friedberg near Frankfurt, Germany, Thursday, December 6, 2018. Presley served in Friedberg from October 1958 to March 1960 as a soldier in the US Armed Forces. (Photo by Michael Probst/AP Photo)

A man carries a sheep after it was rescued from mud in Sanliurfa, Turkey on January 9, 2019. Total of 67 sheep and a donkey rescued from mud by gendarmerie forces, firefighters and local people in Sanliurfa's Bozova district. (Photo by Halil Fidan/Anadolu Agency/Getty Images)

Metropolitan Police run as they escort people, some without shoes, away from a shooting scene in the northwest part of the city on April 22, 2022 in Washington, DC. Police evacuated residents from the shooting scene Friday afternoon and there were reports of several shooting victims. (Photo by Kevin Dietsch/Getty Images)

The tusk of a woolly mammoth that lived some 18,000 years ago, from which researchers sequenced the extinct mammal's entire genome, is seen in northeastern Siberia in this photo from 2015. (Photo by Love Dalen/Handout via Reuters)

A person looks out at Midtown Manhattan in the haze from the Top of the Rock NYC Observation Deck at Rockefeller Center on June 7, 2023. Smoke from Canada’s wildfires has engulfed the Northeast and Mid-Atlantic regions of the US, raising concerns over the harms of persistent poor air quality. (Photo by Timothy A. Clary/AFP Photo)

Photojournalist Evgeniy Maloletka runs from a blaze in a burning wheat field while on assignment after Russian shelling, a few kilometers from the Ukrainian-Russian border in the Kharkiv region, Ukraine, Friday, July 29, 2022. (Photo by Mstyslav Chernov/AP Photo)

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.