(Portland, OR)  --  OMSI is delivering an encore eruption for what might be the world's biggest baking soda and vinegar volcano.  Officials with the museum say they plan to feature the eruption again tomorrow at its After Dark event.  About three-thousand people including experts from Guinness World Records turned out Sunday to watch the 34-foot volcano spew baking soda and vinegar about six to eight feet into the air.  Guinness World Records officials are now working to determine whether the eruption beat the previous world record of a four-foot eruption from a 28-foot volcano.