This is another experiment on the density of liquids. In a small jar put some wine or colored alcohol, and close it with a cork, through which you have passed a small tube, a quill or a hollow straw. In lowering this jar gently in a pail full of water, you will soon see the liquid escape and rise to the surface of the water, describing spirals which resemble smoke, and give a pretty good image, considerably diminished, of a volcano.