1726 October 28, [Jonathan Swift], “The Author Permitted to See the Grand Academy of Lagado.[…]”, in Travels into Several Remote Nations of the World. […][Gulliver’s Travels], volume II, London:[…]Benj[amin] Motte,[…], →OCLC, part III (A Voyage to Laputa, Balnibarbi, Glubbdubdribb, Luggnagg, and Japan), page 78:
I was at the Mathematical School, where the Maſter taught his Pupils after a Method ſcarce imaginable to us in Europe. The Propoſition and Demonſtration were fairly written on a thin Wafer, with Ink compoſed of a Cephalick Tincture. This the Student was to ſwallow upon a faſting Stomach, and for three days following eat nothing but Bread and Water. As the Wafer digeſted, the Tincture mounted to his Brain, bearing the Propoſition along with it.
A soft disk originally made of flour, and later of gelatin or a similar substance, used to seal letters, attach papers etc.
1749, Henry Fielding, Tom Jones, Folio Society 1973 edition, page 202:
The house supplied him with a wafer for his present purpose, with which, having sealed his letter, he returned hastily towards the brook side, in order to search for the things which he had there lost.
[M]y Father, who knew he was well, wafered the paragraph upon a sheet of paper, and sent to his Lodgings.
1913, Joseph Conrad, Chance, New York: Doubleday, Doran & Company, page 81:
[T]he beginning of de Barral's end became manifest to the public in the shape of a half-sheet of note-paper wafered by the four corners on the closed door […].