1To Benjamin Franklin from Jan Ingenhousz, 15 November 1776 (Franklin Papers)
ALS : American Philosophical Society; duplicate: Staatsbibliothek Preussischer Kulturbesitz, West...
2To Benjamin Franklin from Jan Ingenhousz, 4 January 1777 (Franklin Papers)
ALS : American Philosophical Society A little time ago I sent you a lettre by the way of London...
3To Benjamin Franklin from Jan Ingenhousz, 29 January 1777 (Franklin Papers)
ALS : American Philosophical Society As I recieved my lettre Directed to you at Philadelphia back...
4To Benjamin Franklin from Jan Ingenhousz, 2 April 1777 (Franklin Papers)
ALS : American Philosophical Society I recieved a note from the post office of Paris, that a...