Amedeo Avogadro

Born on 9 August 1776 in Turin, Italy, to an aristocratic family, Amedeo Avogadro was an Italian mathematical physicist best known for his hypothesis now called Avogadro’s law. As a young man, Avogadro followed in his father’s footsteps and studied and practiced law. However, finding that he preferred science, Avogadro began privately studying mathematics and physics, focusing on physical chemistry. In 1803 Avogadro published his first scientific paper, on the electrical behavior of salt solutions. Within three years he gave up law and started teaching math and physics at a high school in Turin, and in 1809 he became a senior teacher at the Royal College of Vercelli. It was in 1811 that Avogadro first published what would become his most important scientific contribution: the hypothesis that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. It took decades, however, before Avogadro’s law became widely accepted, in part because the theory disagreed with those of better known scientists at the time, such as John Dalton and Jöns Jacob Berzelius. In 1820 Avogadro became the first chair of mathematical physics at the University of Turin, but lost the job several years later when the university closed for political reasons. A decade later, he was reappointed to the post, which he then held until he retired at the age of 74. Avogadro died at age 79 in 1856.

Date in History: 9 August 1776