From the chemical stores Foyle brought a silvery bit of wire, pure sodium metal. He poked the wire through the open petcock. The sodium ignited when it touched the water and flared with high heat. The heat touched off the Hi-Thrust which burst in a needle flame from the petcock. Foyle closed the petcock with a wrench. The ignition held in the chamber and the lone aft jet slammed out flame with a soundless vibration that shook the ship.