1742-1806. French chemist who in 1790
developed a process for making soda ash
(sodium carbonate, Na2CO3) from common salt
(sodium chloride, NaCl). In the Leblanc
process, salt was first converted into sodium
sulphate by the action of sulphuric acid,
which was then roasted with chalk or
limestone (calcium carbonate) and coal to
produce a mixture of sodium carbonate and
sulphide. The carbonate was leached out with
water and the solution crystallized. Leblanc
devised this method of producing soda ash
(for use in making glass, paper, soap, and
various other chemicals) to win a prize
offered in 1775 by the French Academy of
Sciences, but the Revolutionary government
granted him only a patent (1791), which they
seized along with his factory three years
later. A broken man, Leblanc committed
suicide.