A tall glass or plastic bottle, vegetable oil, food colouring, water, Alka-Seltza or fizzy vitamin tablet.
Fill the glass or bottle about a third full of water, then top it up with vegetable oil. Add a few drops of food colouring and allow to mix with the water. Break the Alka-Seltzer or vitamin tablet into quarters and drop a piece into the glass or bottle and watch what happens. Add more pieces of tablet if you want more bubbles.
These instructions found in The Times newspaper Saturday February 21st.