1From George Washington to Major Benjamin Tallmadge, 13 June 1779 (Washington Papers)
GW is referring to invisible ink, which he sent in late July (see
2From George Washington to Major Benjamin Tallmadge, 25 July 1779 (Washington Papers)
For background on this invisible ink, and its initial use, see
3Enclosure: Samuel Culper to Major Benjamin Tallmadge, 15 July 1779 (Washington Papers)
For Townsend’s first request for invisible ink, see Culper to John Bolton, “June 31” (...
4From George Washington to Major Benjamin Tallmadge, 24 September 1779 (Washington Papers)
...3.” The “stain” was a type of invisible ink. Woodhull, as Samuel Culper, probably enclosed...
5From George Washington to Major Benjamin Tallmadge, 30 October 1779 (Washington Papers)
GW is referring to the chemical reagent for invisible ink (see
6From George Washington to Major Benjamin Tallmadge, 5 February 1780 (Washington Papers)
...last three words. “Stain” and “counterpart” refer to invisible ink and reagent.