Amedeo Carlo Avogadro publishes his memoir about…

Amedeo Carlo Avogadro publishes his memoir about the molecular content of gases.

Born in Turin, Italy in 1776 to a noble family of Piedmont, he had graduated in ecclesiastical law at the early age of twenty and began to practice.

Soon after, he dedicated himself to physics and mathematics (then called positive philosophy), and in 1809 started teaching them at a liceo (high school) in Vercelli, where his family had property.

In 1811, he publishes an article with the title Essai d'une manière de déterminer les masses relatives des molécules élémentaires des corps, et les proportions selon lesquelles elles entrent dans ces combinaisons ("Essay on Determining the Relative Masses of the Elementary Molecules of Bodies and the Proportions by Which They Enter These Combinations"), which contains Avogadro's hypothesis: that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.

Avogadro submits this essay to a French journal, De Lamétherie's Journal de Physique, de Chimie et d'Histoire naturelle (Journal of Physics, Chemistry and Natural History) so it is written in French, not Italian. (Northern Italy is under the rule of the French Emperor Napoléon Bonaparte at this time; Turin has become seat of the prefecture of Pô department.)