1Silas Deane to Robert Morris and the Committee of Secret Correspondence, 23 June 1776 (Franklin Papers)
...point was apparently a communication in invisible ink, which is no longer decipherable; see...
2To Benjamin Franklin from the Chevalier de la Pleignière, 8 March 1778 (Franklin Papers)
...in Franche-Comté. He encloses his secret method of making invisible ink; try it.