INDUCTIVE ACTION ON JETS. 583 



inducing body cannot escape to the ground, and diffuses 

 itself gradually over the whole liquid mass. 



If the electrified body possesses only a weak charge 

 or is held several decimetres from the orifice, the phe- 

 nomenon is very different. The drops do not only not 

 separate but remain even more closely together than in 

 a common jet, so that even the descending portion 

 appears to cohere, as in fig. 311 C. This phenomenon 

 is particularly surprising because a small trace of elec- 

 tricity is sufficient to produce it. In order to explain 

 this effect we must consider that the form of the liquid 

 jet depends essentially on the nature of the liquid and 

 of the substance of which the orifice is made. Thus 

 glass is moistened by water, but not by mercury, and 

 when under ordinary circumstances a jet of mercury 

 issues from a glass spout its form is precisely that of C 

 in fig. 311, because the glass is not moistened by the 

 liquid and the cohesion of the mercury particles not 

 interfered with. Such an interference happens, how- 

 ever, when water issues from glass: the glass is 

 moistened by the liquid, hence the liquid particles 

 which form the outside of the issuing jet lag behind the 

 interior portion of the jet, are made to rotate, and 

 hence thrown sideways. It follows that if the moisten- 

 ing of the orifice by the water jet is diminished by 

 some cause, the jet assumes more nearly the form 

 shown at C. Now this happens precisely when the 

 inducing body has a weak charge or is held at some 

 distance from the jet, for in that case electrical repul- 

 sion takes place at the orifice between the liquid and 

 the glass which diminishes the adhesion between the 

 two, and as a consequence the water issues as a jet of 



