Henri Louis Le Châtelier (1850-1936)

French Chemist and physicist, was born in Paris in October 8th 1850, and died in Miribel-les-Eschelles, Isère, France, in September 17th 1936.

Studied in the Collège Rollin, in École Polytechnique, and became professor, in 1877, of the School of Mines, in Paris. Was Chemistry professor at the Collège de France from 1898 to 1925. In 1884 Le Châtelier enunciated the Law of Mobile Equilibrium, also known as the Le Châtelier principle, that states that when an equilibrium system is disturbed, through variation of concentration, pressure, or temperature, the change tries to reduce the immediate effect of that disturbance. Based on this principle, an industry, for example, can foresee in advance the amount of substance necessary to production.

Le Châtelier also invented the optical pyrometer, an instrument that measures temperature through the observation bodies color. This instrument is used in ceramics, metallurgy and in oven temperature control.