It is an interesting and amusing experiment to inflate a balloon made of gold-beater’s skin (using a little gum arabic to close any holes or fissures), filling it from a bladder or jar, and tying a thread around the mouth of it, to prevent the escape of the gas. When fully blown, attach a fanciful car of colored paper, or very thin pasteboard, to it, and let it float in a large room; it will soon gain the ceiling, where it will remain for any length of time; if it be let off in the open air it will soon ascend out of sight. This experiment may be varied by putting small grains of shot into the car, in order to ascertain the difference between the weight of hydrogen gas and atmospheric air.