Soap Bubbles
and the Forces which Mould Them

THE FORCES WHICH MOULD THEM. 157 ing against the wooden support of the nozzle, will answer quite as well, but is not quite so convenient. The jet will oreak up best to certain notes, but it may be tuned to a great extent by altering the size of the orifice or the pressure of the water, or both. Fountain and Sealing-wax. It is almost impossible to fail over this very striking yet simple experiment. A fountain of almost any size, at any rate between one- fiftieth and a quarter of an inch in the smooth part, and up to eight feet high, will cease to scatter when the sealing-wax is rubbed with flannel and held a few feet away. A suitable size of fountain is one about four feet high, coming from an orifice anywhere near one- sixteenth of an inch in diameter. The nozzle should be inclined so that the water falls slightly on one side. The sealing-wax may be electrified by being rubbed on the coat-sleeve, or on a piece of fur or flannel which is dry. It will then make little pieces of paper or cork dance, but it will still act on the fountain when