[6][7] His writings include two pamphlets relating to the collections made for the colleges in America (1771 and 1774) and Reflections and Observations on the Gout (1772).

[10] In 1782, Sir James connived to get himself arrested by the British so he could present a plan of reconciliation with Great Britain, as he was very suspicious of the French.

[8][11] In a letter to Peter Van Schaak of 17 September 1782, John Jay stated that "If after making so much bustle in and for America, he has, as it is surmised, improperly made his peace with Britain, I shall endeavor to forget that my father has such a son."

[11] Invisible ink was used occasionally after Sir James invented two special fluids, and sent a supply to his brother John Jay in New York.

Letters from Deane were specially handled by John Jay who treated them with the particular chemical to make the writing visible; even Robert Morris, American Revolutionary War financier, submitted his Deane letters to Jay for treatment and kept the invisible ink technique confidential.

Later secret reports of George Washington together with those of his spies in New York, Abraham Woodhull of Long Island (codename: Samuel Culper) and Robert Townsend of New York City (codename: Culper Jr), were written in what Washington termed "white ink"; the second liquid was used to make the secret writing visible.

[13] In 1813, Sir James presented a "Narrative" to Congress which insisted that in Europe he worked to implement plans to attack British commerce and ports.

[15] Together, they were the parents of two children,[13] including Mary (née Jay) Okill (1785–1859), a "vivacious woman"[16] who became a "headmistress of one of the most highly regarded female academies in New York City.

"[15] She married merchant and broker John Okill,[17] and was mother of Mary Helena Okill (1815–1893) (who married Dennis Hart Mahan, a military theorist, civil engineer and professor at the United States Military Academy at West Point; they were the parents of naval historian and theorist Rear Admiral Alfred Thayer Mahan).