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 Los Angeles County firefighter puts water a burning house in a wildfire in the Lake View Terrace area of Los Angeles Tuesday, December 5, 2017. Ferocious winds in Southern California have whipped up explosive wildfires, burning a psychiatric hospital and scores of other structures. Tens of thousands of people have been ordered evacuated. (Photo by Chris Carlson/AP Photo)

Afghans shout anti-U.S. slogans as they burn tires and block a highway during a protest in reaction to a small American church's plan to burn copies of the Quran, at Jalalabad, east of Kabul, Afghanistan, Friday, September 10, 2010. Religious and political leaders across the Muslim world welcomed a decision by the church to suspend its plans to torch copies of their holy book but some said Friday the damage has already been done. (Photo by Rahmat Gul/AP Photo)

A boy looks for sellable materials close to the burning garbage in the permanent waste land under Sylhet City Corporation for a living, on January 15, 2015. (Photo by Md. Akhlas Uddin/Pacific Press)

A burning train wagon is seen after an explosion at Lac Megantic, Quebec, July 6, 2013. A large swath of Lac Megantic was destroyed Saturday after a train carrying crude oil derailed, sparking several explosions and forcing the evacuation of up to 1,000 people. (Photo by Mathieu Belanger/Reuters)

One of the poor families collecting firewood from the street and the burn to feel some warmth in Aleppo, Syria on August 19, 2016. (Photo by Basem Ayoubi/Imageslive/ZUMA Press/Splash News)

A car drives past burning trees as a wildfire rages in the northern city of Haifa, Israel November 24, 2016. Hundreds of Israelis fled their homes on the outskirts of the country's third city Haifa with others trapped inside as firefighters struggled to control raging bushfires, officials said. (Photo by Gil Eliyahu/Reuters)

An animal sprints across a road as the Sugar Fire, part of the Beckwourth Complex Fire, burns in Plumas National Forest, Calif., on Thursday, July 8, 2021. (Photo by Noah Berger/AP Photo)