ELECTRICAL EXPERIMENTS 59 



exception. Drops that were streaming and creeping well 

 often showed most beautifully, when investigated with non- 

 polarisable electrodes, how under the influence of the stream- 

 ing caused by the electric current and the movement towards 

 the positive side connected with it, their shape changed in 

 a corresponding manner, similar to an Amoeba, which creeps 

 alternately in opposite directions. In the accompanying 

 Fig. 8 two consecutive forms of the same drop are depicted : 

 a shows the shape at 12.40 with the position of the poles 

 as indicated ; the peculiarly jagged hinder margin depends 

 on the adherence of the moving drop to the slide. At 

 12.41 the poles were changed; the new positive centre of 

 extension-currents made its appearance at "*, and at 12.45 

 the shape of the drop, as it now gradually moved towards the 

 positive side, was that of the figure &. The same alteration 

 of form and streaming, however, had been already produced 

 several times in this drop, so that the phenomenon figured 

 could not be a mere coincidence. 



At all times in drops that are streaming independently 

 irregularities are met with, which depend principally on the 

 fact that spontaneous streaming movements, which have arisen 

 from other causes, disturb the regular course of events. On 

 this account it is certainly to be recommended, in a repetition 

 of the experiments, to employ stronger electric currents than 

 were at my disposal. 1 This conviction impressed itself upon' 

 me more and more in the course of my experiments, and I 

 certainly think that I should have obtained clearer and more 

 convincing results if I had worked with stronger currents. 



In the course of these experiments it occurred to me that 

 it would be of interest to determine how ordinary oil-drops 

 behave with regard to the electric current, when they are 

 placed in glycerine in which some soap is dissolved. For it 

 is quite clear that the glycerine round the drops of foam 

 always contains some soap. As usual, finely divided lamp- 

 black was mixed with the oil-drops, in order to render 

 distinct any currents that might occur. In the investiga- 



1 Use was made partly of a battery of five moderately large chromic acid 

 elements, partly of one of eight small Grove elements. The action of the two 

 was not essentially different. 



