Leblanc, Nicolas (1742–1806)

French chemist who in the 1780s developed a process for making soda ash (sodium carbonate, Na₂CO₃) from common salt (sodium chloride, NaCl). Soda ash was widely used industrially in making glass, paper, soap, and various chemicals.

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. The process was adopted throughout Europe.

Leblanc was probably born in Indre département. He studied medicine and became physician and assistant in 1780 to Louis Philippe Joseph (who, as duke of Orléans, was guillotined 1793). Leblanc devised his method of producing soda ash to win a prize offered 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. He had no money left to re-establish the process when the factory was handed back to him by Napoleon in 1802. A broken man, Leblanc committed suicide.