Soap Bubbles
and the Forces which Mould Them

the forces which mould them. 147 The tin funnel supplied with an ordinary gazogene answers perfectly. This should be washed before it is used again for filling the gazogene. Bubbles balanced against one another. These experiments are most conveniently made on a small scale. Pieces of thin brass tube, three-eighths or half an inch in diameter, are suitable. It is best to have pieces of apparatus, specially prepared with taps, for easily and quickly stopping the air from leav- ing either bubble, and for putting the two bubbles into communication when required. It should not be difficult to contrive to per- form the experiments, using india-rubber con- necting tubes, pinched with spring clips to take the place of taps. There is one little detail which just makes the difference between success and failure. This is to supply a mouth-piece for blowing the bubble, made of glass tube, which has been drawn out so fine that these little bubbles cannot be blown out suddenly by accident. It is very difficult, otherwise, to adjust the quantity of air in such small bubbles with any accuracy. In balancing