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Events on Wednesday 9 July 1856 1
1776 – 1856Amedeo Avogadro (1776-1856)Died 9 July 1856, aged 80Avogadro, an Italian scientist, died in Turin. He is best known for Avogadro's hypothesis, proposed in 1811, that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. The concept underpins Avogadro's number, a cornerstone of modern chemistry, though it was not widely accepted until after his death.