1Thomas Jefferson to James Jay, 7 April 1809 (Jefferson Papers)
...American Revolution he used an invisible ink of his own invention to pass on intelligence...
2From John Jay to James Jay, 4 January 1776 (Jay Papers)
...Jay may have conducted a political correspondence in invisible ink that has not been found...
3From George Washington to James Jay, 12 May 1780 (Washington Papers)
GW is referring to invisible ink for espionage activities.
4From George Washington to James Jay, 9 April 1780 (Washington Papers)
GW sought a new supply of invisible ink for espionage activities (see