(CNN)Harry Potter wasn’t the only one after the philosopher’s stone.
Isaac Newton’s recently discovered manuscript is his handwritten copy of mid-17th-century Harvard alchemist George Starkey’s procedure for producing “sophick mercury,” a substance seen as a main ingredient for the philosopher’s stone, a fabled stone used in alchemy.
The document had been in private hands for most of the 20th century. The Chemical Heritage Foundation, a nonprofit based in Philadelphia, acquired the 17th-century document through an auction in February.
“The significance of the manuscript is that it helps us understand Newton’s alchemical reading – especially of his favorite author – and gives us evidence of one more of his laboratory procedures,” said James Voelkel, curator of rare books at the Chemical Heritage Foundation’s Othmer Library of Chemical History.