a Diffusion of heavy carbon dioxide gas upwards i Fill a jar with carbon dioxide and invert it over a similar jar full of air After a few moments separate the jars pour a little lime water in the lower one and shake it The lime water will turn milky indicating that the carbon dioxide has fallen into the lower jar because it is the heavier gas ii Repeat the experiment with the carbon dioxide in the lower jar and invert a jar of air on top of it If the jars are left for about 5 minutes carbon dioxide will be carried into the upper jar by diffusion in the same way air will be carried into the lower jar The lime water test will show the presence of carbon dioxide in the upper jar