1881.] Electric Currents through Magnetised Electrolytes. 153 



they are non-magnetic. The rotations may be easily produced by the 

 aid of a current from three or four Groves elements, especially if 

 permanent bar-magnets are used instead of a voltaic coil. The rota- 

 tions by means of vertical currents in the liquid may be produced by 

 the influence of coils or magnets, either above or below the liquids, as 

 well as around it; with magnets, however, in the former positions, no 

 external reversal points occur. A magnet placed entirely above or 

 below the liquid produces the same direction of rotation as a coil 

 placed either above, below, or around it. The direction of rotation 

 produced in a liquid above or within a coil by an upward current in 

 the liquid agrees with that produced by a radial centripetal one within 

 the coil. 



A rotation apparatus of the same kind, interposed as a screen, does 

 not prevent or appear to affect the movements. 



Each electrode may be made to separately revolve in the presence of 

 a coil or magnet by the well-known influence of the radial currents 

 in them ; and the directions of rotation are the same with a tubular 

 magnet as with a coil. In this respect the motion produced by radial 

 currents differs from that produced by axial ones. With each elec- 

 trode diverging currents within the coil or magnet produce dextro, 

 and converging ones Isevo, rotation when the north pole is above. The 

 rotation of the electrodes by means of radial currents appears to be 

 independent of that produced in the liquid by means of axial ones. 



The rotation also of the vessel containing the liquid may be obtained 

 independently of that of the electrodes, by means of the vertical 

 current in the liquid, without the aid of the radial currents in the 

 electrodes. 



The rotations produced by a vertical axis current are not confined 

 to liquids, but may also be produced in a solid conductor, and probably, 

 therefore, with any body conveying an electric current or discharge. 



If we regard a coil as a collection of currents, with a vertical current 

 proceeding upwards or downwards from the centre of the coil, either 

 on its inside or outside, the flow of the liquid is in the same direction 

 as the current in the coil ; and similarly with a vertical current pro- 

 ceeding in like manner from the central parts of a tubular iron or steel 

 magnet, the flow of liquid is in the same direction as that of the 

 nearest layer of hypothetical electric currents in the iron. 



The directions of rotation produced in liquids by means of radial 

 currents inside a magnet or coil are the same as in the solid electrodes, 

 and are laevo at all positions with centripetal currents, and dextro with 

 centrifugal ones, when the north pole is above. A given direction of 

 radial current, whether in the electrodes or electrolytes, or above or 

 below a given pole, provided that the -pole was not reversed in posi- 

 tion, produced the same direction of rotation. The direction of rota- 

 tion produced by a radial current approaching a vertical coil or magnet 



M 2 



