Another experiment involves creating an Alka-Seltzer water lava lamp. A 16-ounce soda pop bottle should be emptied and cleaned, then filled 3/4 full with vegetable oil and the rest of the way with plain water, just up to the neck of the bottle. Color the water with 10 drops of food coloring. Break up one Alka-Seltzer tablet into about six to eight pieces and drop them in one at a time, watching for a reaction. When the reaction is completed, twist the bottle top on tightly. Shake the bottle, mixing contents thoroughly and observe the results.