Henry Cavendish (1730-1810) was an unusual man of unusual capabilities in science. He is probably one of the most accomplished scientists with the least credit given to his discoveries as he severely lacked the social skills to communicate his work to the rest of the world. Even though he likely suffered from Anspergers syndrome, he was one of the first to perform detailed analyses of our atmosphere and led the way in determining the composition of air, discovered the chemistry of hydrogen and showed that water was a compound made up of hydrogen and water. He also performed the first determination of the gravitational constant and the density and mass of the earth using a specially designed Cavendish torsional balance. We will review the man and his contributions to chemistry and atmospheric science, and focus on his techniques of collecting gases above water as noted in his work "On Fractious Airs" (1766), as well as results from his published work “Experiments on Air” in Philosophical Transactions 75, 372 (1785). Cavendish was a pioneer in Atmospheric Chemistry and deserves to be considered among the Fathers of Atmospheric Chemistry.