 Soviet rocket engine researcher Valentin Glushko experimented with hypergolic fuel as early as 1931.It was initially used for "chemical ignition" of engines, starting kerosene/nitric acid engines with an initial charge of phosphorus dissolved in carbon disulfide.Starting in 1935, Prof. O. Lutz of the German Aeronautical Institute experimented with over 1000 self-igniting propellants.