1879.] Spontaneous Segmentation of a Liquid Annulus. 49 



By drawing lines through all the positions of each particular metal 

 in the tables of solutions of different strengths of either of the salts 

 employed, it was found that the position of pairs of metals of like 

 properties, such as magnesium and zinc, nickel and cobalt, rhodium 

 and iridium or platinum, lead and tin, &c, often varied together, and 

 described similar curves or lines of variation. 



A much greater number of variations of relative electric position of 

 the metals occurred in the cold and hot solutions of potassic cyanide 

 than in either those of the chloride, bromide, or iodide, whether cold 

 or hot, and the amounts of such variations were also much greater in 

 the cyanide solutions. 



Agitation of the immersed metals is well known to influence the 

 current. Shaking one of the metals reversed occasionally the direc- 

 tion of the current ; palladium was the metal which most frequently 

 manifested this effect. The agitation of that metal rendered it either 

 more negative or less positive in a considerable degree, especially in 

 solutions of potassic chloride and cyanide. In those of the bromide, 

 antimony was the metal the current from which was most affected by 

 shaking. The effect of shaking was less in the iodide solutions than 

 in those of the bromide. 



VIII. " On the Spontaneous Segmentation of a Liquid Annu- 

 lus." By A. M. WORTHINGTON, M.A. Communicated by 

 Balfour Stewart, F.R.S., Professor of Natural Philosophy 

 in Owens College, Manchester. Received December (>, 

 1879. 



In seeking an explanation of the appearance of a definite number of 

 lobes in the liquid annulus which is formed at a certain stage of the 

 splash of a drop that has fallen vertically on to a horizontal plate, T 

 was led to make some experiments on the spontaneous segmentation 

 of such an annulus lying on a plate with a view to ascertaining 

 whether the relation that exists between the dimensions of the annulus 

 and the number of drops into which it will spontaneously split, is the 

 same as for a straight cylinder of liquid under similar conditions. 

 Finding that the relation was the same, it then occurred to me that 

 by liberating an annulus in air without contact with any solid, a 

 direct experimental proof might be obtained of the law of segmentation 

 of a free cylinder. 



It has been shown mathematically in various ways, and experi- 

 mentally by M. Plateau, that the equilibrium of a free cylinder of any 

 liquid, under the influence of surface tension only, becomes unstable 

 as soon as the length exceeds 7r times the diameter ; and it has been 

 regarded as a necessary consequence of this that such a cylinder, if 



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