1From Benjamin Franklin to Jan Ingenhousz, 30 September 1773 (Franklin Papers)
ALS (letterbook draft): American Philosophical Society I rejoic’d as much as any Friend could do,...
2From Benjamin Franklin to Jan Ingenhousz, 18 March 1774 (Franklin Papers)
ALS : Harvard University Library I have lately been favoured with yours of the 24th past. I am...
3From Benjamin Franklin to Jan Ingenhousz, 12 February[–6 March 1777] (Franklin Papers)
ALS : Yale University Library; incomplete draft and copy: Library of Congress I received your...
4From Benjamin Franklin to Jan Ingenhousz, 26 April 1777 (Franklin Papers)
ALS : Henry Huntington Library I find by your Favour of the 2d Inst. that my Letter to you had...
5From Benjamin Franklin to Ingenhousz, 4[–5] May 1779 (Franklin Papers)
LS : American Philosophical Society I received your kind Letter of last Month, and I forwarded...
6From Benjamin Franklin to Ingenhousz, 22 November 1779 (Franklin Papers)
Copy: Library of Congress I received yours of the 18th. and see with great Pleasure that you have...
7From Benjamin Franklin to Ingenhousz, 2 October 1781[–21 June 1782] (Franklin Papers)
AL (draft) and LS : Library of Congress It is a long time, my dear Friend, since I have had the...
8From Benjamin Franklin to Ingenhousz, [21 June 1782] (Franklin Papers)
AL (draft), press copy of L , and copy: Library of Congress An Attempt to explain the Effects of...
9From Benjamin Franklin to Jan Ingenhousz, 16 May 1783 (Franklin Papers)
LS and incomplete AL (draft): Library of Congress I have before me your three Favours of Feby....
10From Benjamin Franklin to Ingenhousz, 1 June 1783 (Franklin Papers)
ALS : American Philosophical Society This will be delivered to you by an ingenious young Friend...