French scholar (1790-1832) who published the first translation of the Rosetta Stone hieroglyphs in 1822. Rare ALS in French, signed "J. F. Champollion, Le jeune," one page, 7 x 8.5, April 12, 1823. Letter to the famous German linguist Julius Heinrich Klaproth (1783-1835) in Paris. Translated in full: "Sir I accept with pleasure the exchange you were kind to propose and I send you the first published part of my 'Egyptian Pantheon.' The others will be sent to you as they will appear in print. I will be very flattered if they meet with your approval. Please accept the expression of the high consideration in which you are kept by your humble servant." Reverse of second integral page bears an address panel in another hand, as well as docketing. In fine condition, with scattered light foxing. Neither the first nor the following parts of Champollion's masterwork met with Klaproth's approval, who criticized the French scholar's work in his own book published four years later: 'Letter on the Discovery of Hieroglyphs.' A very important exchange between the claimant of a major discovery and his main disbeliever.