A century earlier, Henry Cavendish had noted the existence of a residual gas when oxygen and nitrogen are removed from air, but its importance had not been realized.

早在一个世纪以前，亨利·卡文迪什就注意到：当氧和氮从空气中除去时，会有残余气体存在；但人们还没有认识到这些残余气体的重要性。