French chemist, Joseph Gay-Lussac is most famous for his description of the gas law, Gay-Lussac's Law.

How did Gay-Lussac use balloons to study chemistry in the early 1800s?

He increased the kinetic energy of the gas in the balloon as it's particles collide more frequently, thus increasing pressure of the balloon.


http://en.wikipedia.org/wiki/Gay-Lussac's_law