# How was the Avogadro's law discovered?

Avogadro's Law is one of the early gas laws, and proposed that the volume expressed by a gas was proportional to the number of gaseous molecules given equivalence with respect to temperature and pressure, $V \propto n$. And please note that the behaviour of gases in these scenarios allowed chemists and physicists to get a pretty shrewd idea of molecular behaviour simply by measurement of the macroscopic observables of mass, temperature, pressure, and volume.
Avogadro's original law proposed that ${V}_{\text{volume of gas"propn_"number of gaseous particles}}$...i.e. $V = k n$...with $k = \text{some constant of proportionality}$