From John Jay
Fish Kill [N.Y.] 19th novr 1778
This will be delivered by my Brother, who will communicate & explain to your Excellency a mode of Correspondence, which may be of use, provided proper agents can be obtained. I have experienced its Efficacy by a three Years Trial. We shall remain absolutely silent on the Subject.1 I have the Honor to be with the highest Esteem & Respect Your Excellencys most obedient Servant
1. James Jay (1732–1815), a physician and amateur chemist, studied and practiced medicine in Great Britain from the 1750s until the outbreak of the Revolutionary War, and was knighted by King George III in 1763 for his efforts in raising funds for King’s (Columbia) College of New York. Jay developed his invisible ink in 1775 and used it throughout the war in correspondence with his brother. He never disclosed the recipe, and although he exported small quantities to America for use in the Culper spy ring, it always remained in short supply. A correspondent would write a letter using the ink on white paper, and the recipient would apply a reagent in order to read it. GW referred to the concoction as the “sympathetic stain,” and used the code word “medicine” in his future correspondence with James Jay (see GW to Elias Boudinot, 3 May 1779, and to James Jay, 12 May 1780; for more on the ink and its use, see Rose, Washington’s Spies description begins Alexander Rose. Washington’s Spies: The Story of America’s First Spy Ring. New York, 2006. description ends , 106–11, 310–12).