What do you mean by ghost fire?

Jack-o'-lantern is a strong green phosphorescence, which appears in cemeteries or villages at night. Secular superstition, thinking that it is a ghost fire, with light and no flame, is produced by the burning of phosphide.

Ghost fire is actually phosphorus fire, which is a very common natural phenomenon. Usually in rural areas, more than in dry days in summer. But occasionally it appears in the city. Because human bones contain phosphorus, the body changes after decay, and phosphorus is converted from phosphate to phosphine.

Phosphine is a gaseous substance, and its ignition point is very low, only 40 degrees. Contact with air at room temperature will burn. After phosphine is produced, it is emitted into the air along cracks or holes in the ground, and emits blue light after burning. This is phosphorus fire, also known as "ghost fire".

Because walking will drive it to move backward (because the pressure is low where the flow velocity is high), it is scary to look back, so it is called "ghost fire" by superstitious people. The color of jack-o'-lantern changes with the color of elements contained in human body. Sometimes we can see that the colors of jack-o'-lantern are green, blue and red. If there is a special color, it means that there are many trace elements in the body of the deceased.

Legends about jack-o'-lantern:

There are legends about ghost fires all over the world. For example, in Ireland, the ghost fire originated from the later Halloween ghost fire, and there is also a story about the ghost fire in Andersen's fairy tales, "Ghost fire enters the city". It is said that when German alchemist Brandt discovered phosphorus in 1669, he used the Greek word "Jack lamp" to name this substance.

There are also many legends about ghost fires in China. Ghost fire is often mentioned in Pu Songling's Strange Tales from a Lonely Studio in Qing Dynasty, but people think it is a ghost lamp patrolling in Yan Luowang. However, as early as the Southern Song Dynasty, some people understood the relationship between phosphorus and the appearance of jack-o'-lantern. For example, Volume 4 of Lu You's Notes on Learning Old Age in the Southern Song Dynasty mentioned that "... the so-called human blood is phosphorus, which is true."