Things will get a little explosive at the Franklin Institute on Saturday, Aug. 15, when "Don't Try This at Home Day" brings large-scale science experiments and demonstrations to the Philadelphia museum. The day's experiments include a blast involving 500 balls and liquid nitrogen, along with a multi-balloon explosion powered by hydrogen. The Franklin Institute will also put gravity to the test by dropping watermelons, water balloons and other objects during a multi-stage demonstration. The Periodic Chef will present a series of short demonstrations that use familiar ingredients to explore the science behind cooking. The Philadelphia Water Department will also explain how litter and debris can affect environmental systems and the workers responsible for maintaining them.