For this demonstration I use my own special formula for extra strong soap bubbles. I use one part Dawn soap, one part glycerin, and two parts water. I dip the bottom end of the funnel into the soap bubble mixture and blow through the wide top to create large bubbles. The rest of the demo just needs an empty fish tank and some dry ice. This is one of my favorite demos to teach the concepts of the density and buoyancy of different gasses.