Biography of Jean-Baptiste Biot (1774-1862)

Physicist and French chemist born on April 21, 1774 in Paris and died on 3 February 1862 in the same city, who stood out as a precursor to the studies in the field of the Polarimetry.

BIOT enlisted in the French army with only eighteen years; He/She served in the artillery, although for a short space of time already that soon abandoned it to study Sciences at the prestigious École Polytechnique, so that in 1792 he/she gave classes of physics as a professor at the Collège de France. He/She did extensive research in diverse fields; He/She accompanied Gay-Lussac in its first ascent aerostatic building in 1804 one of the first hot-air balloons, which were meteorological and magnetic observations at high altitudes; and it came to form part of a series of geophysical and astronomical expeditions to Spain and Scotland (Orkney Islands). But the best-known works of Biot are those relating to the field of optics, to demonstrate by time first making some crystals of quartz rotated the plane of polarization of the light, while other crystals produced the same effect but in the opposite direction. In 1815 it was observed that certain liquids also developed this effect to be penetrated by a polarized beam of light, feature which later extended to certain solutes (for example: sugar).

After numerous observations, Biot came to the conclusion that this optical activity was a reflection of a molecular property, so that the degree of rotation of the plane of polarized light was proportional to the length of the journey and in the case of solutions, to the concentration of the solute optically active; While it was inversely proportional to the square of the wavelength of light (electromagnetic wave used). Basically with these statements in 1870 Biot established a law that bears his name (law of Biot), which subsequently proved to be very useful for the development of the Polarimetry. Biot law allows obtaining information about the molecular configuration of the tested substances, and variations in the rotation of the plane of polarization in polarized light wavelength was later used in the determination of the molecular types.

BIOT made friends with great contemporary scientists such as Laplace, and was a member of the Academy of Sciences and the Office of French lengths. His many writings include as most important the following: analysis of the Treaty of celestial mechanics of Laplace; Basic Treaty of physical astronomy; Tried to experimental physics; Collection of physical, astronomical and geodetic observations.