The French chemist and physicist Joseph Louis Gay-Lussac (1778-1850) is distinguished for his work on gas laws and for his studies of the properties of cyanogen and iodine.

Born at Saint-Léonard in the department of Vienne, Joseph Gay-Lussac came from a solidly bourgeois family. The storms of the French Revolution delayed his education, but largely by his own disciplined self-teaching, he passed the examinations and was admitted to the prestigious École Polytechnique in 1797. Here he became the protégé of Claude Louis Berthollet.

In these early years Gay-Lussac's skill as an experimenter and scientific instrument maker was well developed. In 1802 he published a law of the expansion of gases by heat, which became known as Charles' law. In 1804 he made an ascent of 23,000 feet in a balloon to collect samples of the atmosphere for chemical analyses and to measure the dependence of the...