72 Mr. J. Enright on Electrifications due 



of hail during thunderstorms. So close did the resemblance 

 between my soap-bubbles and those "fire balls," as they are 

 sometimes called, appear to me that I hastened to ascertain 

 by experiment whether or not my speculations with regard to 

 them comprised any truth. 



Soap-bubbles were accordingly blown by means of the 

 generator containing Zn + HCl. Only small ones could be 

 obtained, and these shot away towards the ceiling so quickly 

 that it was not easy to touch them with the metallic part of 

 the proof plane. Some few, however, were caught and the 

 proof plane was found to be very slightly negatively elec- 

 trified. Some better plan had to be tried. The end of the 

 delivery-tube was placed under the surface of the soap solu- 

 tion while gas was ecaping. A great mass of bubbles were 

 produced on the surface, and some of them toppled over tbe 

 side of the dish and fell towards the floor on account of the 

 greater quantity of water in them. These were caught on the 

 metallic part of the proof plane, and on testing the latter it 

 was found to be strongly charged, the sign being negative, 

 which bore out the idea of the bubble being a charged 

 condenser. 



Another form of the experiment then occurred to me. The 

 dish containing the soap solution was attached to an insulating 

 handle and then set on the table. The end of the delivery- 

 tube was once more dipped into the soap mixture, and a mass 

 of bubbles was as before produced. The delivery-tube was 

 then withdrawn, and the dish lifted from the table by an insu- 

 lating handle. It was kept thus insulated until, in the course 

 of a few minutes, the bubbles broke up, allowing the hydrogen 

 to escape. The dish was then tested and found to have a 

 negative charge. The soap-bubble blown as described was 

 thus proved to be a charged condenser. 



If by any process a mass of electrified air were enclosed by 

 vesicles of water, or any other conducting material, a free 

 charge would be developed on the outside which would cause 

 the whole mass to be attracted or repelled according to the 

 electrical state of proximate objects. In a recent number 

 of ' Nature ' I find an account of a thundercloud behaving in 

 a manner at once explained by this hypothesis. The observer 

 describes it as appearing to detach itself from a mass of cloud, 

 gradually descend, and immediately after draw itself up again. 

 The descent would be due partly to the attraction of the earth 

 and to the repulsion of similarly electrified clouds above it. 

 On touching the earth the free charge would escape, and the 

 clouds, which at first repelled, would now attract, it, causing 

 its ascent. 



