Back in the day, specifically a Thursday at noon sometime around 1662, a guy named Robert Boyle discovered that a gas’s volume is inversely related to pressure. It sounds obvious today but back then it was a leap for the physical sciences. In fact, Boyle’s work even influenced Isaac Newton. Talk about bragging rights.

A little over 100 years later around 1780, Jacques Charles, after launching the world’s first hydrogen balloon and doing other cool stuff, discovered that a gas’s volume is directly related to it’s temperature. This is now known as Charles’ Law, although interestingly enough, Charles never published the law himself. Joseph Louis Gay-Lussac was the one who published the law and credited Charles with discovering the relationship, naming the law after him. Pretty noble of the guy if you ask me.

Finally, around 1811, Amedeo Avogadro discovered the relationship between the amount of molecules in a gas and a gas’s volume. The result: If the pressure, temperature, and volume of any two ideal gases are the same then each have the same number of molecules present.