There’s something soothing and mesmerizing about lava lamps, the way color is animated seemingly by magic. Here’s how to make your own using simple materials.
Fill one-quarter of a one-liter clear bottle with water, then, using a funnel, add vegetable oil until it’s about an inch and a half from the top. Notice how the oil floats above the water. Wait a few minutes for the bubbles in the oil to dissipate. Then, squeeze five drops of food coloring into the bottle; they’ll sink to the bottom. Plop in two tablets of Alka Seltzer and watch as they dissolve, producing carbon dioxide that rises to the surface and brings water and food coloring with it. When the gas is released at the top, the water and food coloring sink back down. Put a lid on your bottle for use another day!