He first published his wo
He first published his work in 1811, but it went largely ignored for nearly fifty years until it received the endorsement of Stanislao Cannizzaro at the first international scientific conference, convened in Karlsruhe by Friedrich Kekule.  Following his hypothesis, he demonstrated the error in Dalton's contention that water consisted of a single atom each of hydrogen and oxygen and correctly deduced the diatomic nature of oxygen and nitrogen.  This also led to his creation of the term molecule from the Latin for "small masses".  FTP, name this Italian physicist whose hypothesis held that all gases at a given temperature, pressure and volume had the same number of particles.
He first published his work in 1811, but it went largely ignored for nearly fifty years until it received the endorsement of Stanislao Cannizzaro at the first international scientific conference, convened in Karlsruhe by Friedrich Kekule.  
Amedeo Avogadro