The Science Continues! We feed 72 volts and 4 amps of direct current through an upside-down bottle of salt water via six carbon contacts. Hydrogen bubbles off the negative contact rods, and Oxygen off the positive. 2H2O(l) ? 2H2(g) + O2(g) Three hours later we have a 4 Gal bottle filled with 1/3 water and about 2/3 Oxygen/Hydrogen (some chlorine is produced) 100,000 Volts across a spark gap at the top and Liftoff! The combusting gasses force water out, in turn propelling the rocket. The only exhaust? Water! Go here for more details and instructions! Stay tuned for more uplifting science!