Autograph Letter Signed, about discovering the truth about Nicholas Leblanc (1742-1806) and his extraction of sodium carbonate from sea salt.. In French. 1 page 8 x 5 inches, fine. 26 November 1856. Jean Baptiste Dumas (1800-1884), French chemist, prominent teacher and investigator, one of the first men in France to realize the importance of experimental laboratory teaching. In the Essai Statique Chimique (1841), he treated the chemistry of life, both plant and animal.