the water refuseth to receive them into their bosome ... and suffers them to float

I have been reading about witchcraft. I have been reading specifically about the circa 17th-century European and North American idea of the witch, in part because I am trying to develop my own story about witches with as little overlap with Harry Potter as possible. I feel like the popular image of witches as having pointy hats, brooms, and cauldrons is already pretty locked down by Harry Potter. To this end, I've read 17th century witch hunter Matthew Hopkins' manual The Discovery of Witches and the Wikipedia article for The Crucible (because I could read that at the reference desk) and begun a non-fiction book called A History of Magic and Witchcraft: Sabbats, Satan and Superstitions in the West, by Frances Timbers. Here is my list so far of witch lore that does not occur (or is mentioned only passingly) in Harry Potter:

• familiars or imps – The types of animals that are familiars or imps appear in Harry Potter but are not called familiars or treated as demonic spirits or parts of the witches' souls, with the exception of Nagini. Also crucial: familiars' funny little names.
• covens or sects
• the Devil's book of names, or covenants with the Devil more generally
• witch hunters
• the Witches' Sabbath
• the term "maleficium" to refer to witchcraft
• a third teat or other marks of the Devil
• pricking marks of the Devil
• the Demonology of King James
• floating in water – Apparently it is the Demonology that claims that witches deny their baptism when they form a covenant with the devil, and that is why they float!
• poppets
• flying or dancing naked
• witch trials, interrogations, and executions, e.g., hangings and pressing – Harry Potter refers to burnings, which never happened in North America

Here is a list of familiars' funny little names from The Discovery of Witches:

• Holt, a white kitten
• Jarmara, a fat spaniel with no legs
• Vinegar Tom, a greyhound
• Sack and Sugar, a black rabbit
• Newes, a polecat
• Elemanzer
• Pyewacket
• Peckin the Crown
• Grizzel
• Greedigut

May update as I continue my research.