An Italian chemist and physicist who provided Avogadro’s law as a way of calculating molecular weights from vapour densities. He was educated and graduated in ecclesiastical law; however, he had a keen interest in the natural sciences and received private tuition in physics and mathematics. He published his hypothesis, known now as Avogadro’s law, while working as a schoolteacher. He was appointed to the first chair in mathematical physics at Turin University in 1820. The importance of his work was first recognized by the Italian chemist Stanislao Cannizzarro (1826–1910) in 1858, shortly after Avogadro’s death.