1879.] 



Electricity on Colliding Water Drops. 



409 



stoneware bottle, the other pole being to earth. If the fingers be 

 slightly moistened, the body may be thrown into the circnit, appa- 

 rently without diminution of effect. This perhaps ought not to sur- 

 prise us, as in any case the electricity has to traverse several inches 

 of a fine column of water. On the other hand, it appeared that most 

 of the electromotive force of the Grove cell was necessary. 



Further experiment showed that even the discharge of a condenser 

 charged by a single Grove cell was sufficient to determine coalescence. 

 Two condensers were used successively ; one belonging to an in- 

 ductorium by Ladd, the other made by Elliott Brothers, and marked 

 " Capacity Farad." Sometimes even the " residual charge " sufficed. 



It must be understood that coalescence of the jets would sometimes 

 occur in a capricious manner, without the action of electricity or 

 other apparent cause. I have reason to believe that some, at any rate, 

 of these irregularities depended upon a want of cleanness in the 

 water. The addition to the water of a very small quantity of soap 

 makes the rebound of the jets impossible. 



The last observation led me to examine the behaviour of a fine 

 vertical jet of slightly soapy water ; and I found, as I had expected, 

 that no scattering took place. Under these circumstances the approach of 

 a moderately electrified body is without effect, but a more powerful 

 influence scatters the drop as usual. The apparent coherence of a jet 

 of water when the orifice is oiled was observed by Fuchs, and appears 

 to have been always attributed to a diminution of adhesion between 

 the jet and the walls of the orifice. 



Some further details on this subject, and other investigations re- 

 specting the phenomena of jets, are reserved for another communication, 

 which I hope soon to be able to present to the Royal Society ; but I 

 cannot close without indicating the probable application to meteorology 

 of the facts already mentioned. It is obvious that the formation of 

 rain must depend very materially upon the consequences of en- 

 counters between cloud particles. If encounters do not lead to con- 

 tacts, or if contacts result in rebounds, the particles remain of the 

 same size as before ; but, if the issue be coalescence, the bigger drops 

 must rapidly increase in size and be precipitated as rain. Now, from 

 what has appeared above we have every reason to suppose that the 

 results of an encounter will be different according to the electrical 

 condition of the particles, and we may thus anticipate an explanation 

 of the remarkable but hitherto mysterious connexion between rain. 

 and electrical manifestations. 



vol. XXVIII. 



