July 9th – Amedeo Avogadro died on this day in 1856

Lorenzo Romano Amedeo Carlo Avogadro was an Italian scientist. His hypothesis – now known as Avogadro’s Law – states that equal volumes of gases at a given temperature and pressure contain the same number of molecules. In tribute to him, the number of elementary entities (atom, molecules,ions or other particles) in  of a 1 mole substance, 6.022140857(74)×10²³, is known as the Avogadro constant, one of the seven SI  base units and represented by N_A.