There's an ancient alchemy book that had purposeful mistakes made in it to fool people from understanding its cryptic recipes. (Can't remember the name of it at the moment) In Harry Potter, he gets the halfblood prince's recipe book that has the same purposeful mistakes corrected. REAL-LIFE alchemy example written into the Harry Potter story, among others alluding to real witchcraft examples. Rowling would have had to have been a practicioner herself to know all of this, or she didn't write it at all. I definitely agree with the latter conclusion.