Gay-Lussac was a French chemist and physicist who showed that all gases expand by the same fraction of their volume for a given temperature increase—which led to the devising of a new temperature scale whose thermodynamic significance was later established by Lord Kelvin. By taking measurements from a balloon above 20,000 feet (6,000 m), he concluded that Earth’s magnetic intensity and atmospheric composition were constant to that altitude. Gay-Lussac also helped to discover what element? Discuss