The „London-Leiden Magical Papyrus“ is the most extensive ancient manual of magical and ritual practice known to us today. It was found in Egypt around Thebes and is dated to the late 2nd or early 3rd century A.D. The instructions in the papyrus were predominantly written in the ancient Egyptian language -> Demotic with some lines and comments also written in Greek.
The scroll is particularly interesting for research in ancient magic because its author did not just copy an existing manual 1:1, he actually researched multiple existing manuals and instructions, experimented himself, commented a lot, and created a unique handbook of individual magical, medical, and ritual practices.
The papyrus scroll measures ca. 500 x 34 cm and is inscribed on both sides with 1.254 lines: 1.227 in Demotic and 27 in Greek. There are almost 100 individual ritual instructions, recipes, medical instructions, and hymns preserved in the manual. That is why it is also called the „great“ London-Leiden Magical Papyrus.
Why is it called „London-Leiden“? Because when it was purchased at the antiquities market during the early 1900s it was allready cut in two pieces and probably sold individually. The man who had purchased the papyri sold one part to the Dutch government in 1828 and the other was bought in 1857 for the British Museum. Until today the first part of the scroll is kept at the British Museum in London while the second part is kept at the Rijksmuseum van Oudheden in Leiden.
In academic publications the papyrus is referred to as „pdm xiv“ and „PGM XIV“ which stands for papyri demoticae magicae (Demotic magical papyri) and papyri graecae magicae (Greek magical papyri).
You can find more information about the modern history of the papyrus as well as an English translation in the publication of Francis Llewellin Griffith and Herbert Thompson (1904) which can be downloaded for free at archive.org: https://archive.org/details/cu31924026874523/page/n11/mode/2up
The photo below shows the end of the scroll (to the left). You can see the damage done by the extensive use of the papyrus.