Henry Cavendish made a significant contribution to chemistry by discovering that hydrogen was a distinct element in air. He accomplished this by calculating the densities of the various components of air. He also receives credit for determining the value of G, which is the gravitational constant.
In 1766, Henry Cavendish found that hydrogen, which he called flammable air, was an element in air. He was also able to show that another element was in the atmosphere, which Lord Rayleigh and William Ramsay later identified as argon. Other discoveries credited to Cavendish are water's composition and the percentage composition of the gases found in air now known as nitrogen and oxygen.
In physics, his contributions included calculating the gravitational constant and Earth's density and mass. He made these discoveries in the 1790s. Cavendish was born in 1731 and died in 1810.