﻿150 Prof. Burton and Mr. Wiegand : Effect of 



whether the air can be anywhere squeezed out during the 

 short time over which the collision extends. 



" It would seem that the electrical forces act with peculiar 

 advantage. If we suppose that upon the whole the air 

 cannot be removed, so that the mean distance between the 

 opposed surfaces remains constant, the electric attractions 

 tend to produce an instability whereby the smaller intervals 

 are diminished while the larger are increased. Extremely 

 local contacts of the liquids, while opposed by capillary 

 tension which tends to keep the surfaces flat, are thus 

 favoured by the electrical forces, which moreover at the 

 small distances in question act with exaggerated power." 



From our study of the phenomena of such streams we are 

 convinced that this explanation is at most merely a first 

 approximation to the whole action. The part that surface 

 tension can play is limited in the way noted above by 

 Rayleigh. The identical appearance of the charged and 

 uncharged streams, just after breaking into drops, shows 

 that surface-tension is not altered in a way which would 

 give rise to larger drops at breaking. It has been pointed 

 out by Merritt and Barnett * that the apparent diminution of 

 the surface-tension when, for example, soap-bubbles, globules 

 of mercury, &c, are electrified, is probably due to the fact 

 that the surfaces employed are convex, and that " in the 

 case of a concave charged surface a consideration of the 

 electrostatic forces would lead us to expect an apparent 

 increase in the strength of the surface film/' If the electro- 

 static forces be allowed for in these cases, these writers find 

 no perceptible direct variation in the surface-tension of a 

 charged water or mercury surface. Such a problem as we 

 are discussing here is of course independent of the phenomena 

 involved in the capillary electrometer (see Barnett) f. Even 

 treating the effect of the electrostatic forces as a diminution 

 in the surface-tension, the experiments of Nichols and CTarkJ 

 show that for the low voltages employed in these drop experi- 

 ments such diminution would be itself imperceptible. The 

 effect must depend then directly on the electrostatic attrac- 

 tions and repulsions between the drops themselves. 



Purpose of the Experiments. 



The purpose of the following experiments was (1) to 

 examine a given stream under influence of charges induced 



* Phvs. Eev. x. 1900, p. 65. 

 t Phys.Rev. vi. ]«98, p. 257. 

 X Phvs. Rev. iv. 1897, p. 375. 



