A while back I posted an item from Steve Spangler’s Science site that demonstrated how to make lava lamps. I decided to go ahead and try it and I filmed it. The materials that are required for the demo are shown below. As the video shows the peanut butter jar is filled with 3/4 vegetable oil and 1/4 colored water. Place an 1/8 of an Alka-Seltzer tablet into the jar. The Alka-Seltzer reacts with the water to form carbon dioxide gas bubbles. The gas is less dense than the water or oil. The carbon dioxide gas bubble attach themselves to the colored water, causing them to rise to the surface. When the gas breaks through to the surface the higher density colored water droplets sink back down into the jar. The second part of the video shows the same demonstration, this time in a large test tube.