A demonstrator smashes a shop window during a protest condemning the arrest of rap singer Pablo Hasél in Barcelona, Spain, Saturday, February 20, 2021. A fifth night of peaceful protests to denounce the imprisonment of a Spanish rap artist once more devolved into clashes between police and fringe group members who set up street barricades and smashed storefront windows in Barcelona. (Photo by Joan Mateu/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.

People are seen through a window as they attend the traditional wedding ceremony of Emir's 7 children in Abuja, Nigeria, December 26, 2020. (Photo by Afolabi Sotunde/Reuters)

A woman takes photographs of falling snow from a window during a heavy snowfall, amid the coronavirus disease (COVID-19) pandemic in Seoul, South Korea, January 12, 2021. (Photo by Kim Hong-Ji/Reuters)

A zookeeper counts penguins through an observation window during the annual stocktake at ZSL London Zoo in central London on January 3, 2023. (Photo by Justin Tallis/AFP Photo)

A man looks out of a window as Palestinians inspect the site and search for casualties of an overnight Israeli air strike on a house at al-Shati (Beach) refugee camp, in Gaza City, on July 15, 2025. (Photo by Mahmoud Issa/Reuters)

In this October 27, 1983 file photo, soldiers brandish captured AK-47 rifles from the windows of a civilian vehicle as they drive near Point Salines Airport in St. George, Grenada. In 1983, U.S. forces invaded the Caribbean island of Grenada after accusing the government of allying itself with Communist Cuba. (Photo by Doug Jennings/AP Photo)

A homeless street child looks in the window of a car in Jammu, India, Friday, January 6, 2017. Some 800 million people in the country live in poverty, many of them migrating to big cities in search of a livelihood and often ending up on the streets. (Photo by Channi Anand/AP Photo)