152 Dr. Gr. Gore. On some Effects of Transmitting [Dec. 15, 



influence of which rotations in the interior of hollow - magnets have 

 hitherto been ascribed.* 



It is here shown that a colnmn of an electrolyte placed nnder similar 

 conditions to an iron wire or rod, when subjected to electro-magnetic 

 torsion (i.e., enclosed by an electro-magnetic helix, and traversed 

 axially by an electric current), is twisted in a similar manner to the 

 wire or bar. This effect, however, in the case of a liquid is not limited 

 to paramagnetic substances, nor is the direction of torsion altered by 

 the magnetic character of the liquid. 



The rotations produced in liquids by means of axial currents are- 

 opposite in direction at the two ends of the voltaic helix, are strongest 

 at the poles, and at a little distance beyond them, and null at the 

 centre of the tube ; they may be produced at a distance of several 

 inches beyond the poles. The directions of rotation within the tube, 

 and to a short distance beyond the poles, are in the case of an electro 

 or permanent magnet opposite to those produced by a voltaic selenoid. 

 A magnet tube, therefore, has three points of no rotation with an 

 axial current, viz., one at its centre, and one near each end, whilst a 

 selenoid has only the former one. The existence of the outer neutral 

 points produced by a magnet depends upon the position of the latter 

 to the liquid, and the distances of those points from the poles of the 

 magnet are affected by various circumstances, which are described in 

 the communication. If the magnet is wholly above or below the 

 portion of liquid traversed by the axial current, the outer neutral 

 points do not occur. 



By the influence of a vertical current, the liquid as a whole may be 

 made to rotate in either single direction ; the motion at one end of the 

 column, therefore, is not dependent upon the opposite direction of 

 motion at the other, and torsion is not a necessary form of the effect. 

 The reaction of the liquid in the production of the rotation is neither 

 upon another portion of the liquid, nor upon the electrodes, nor upon 

 the walls of the containing vessel, but upon the adjacent magnetised 

 body, and the rotation of the liquid is confined to the portion traversed 

 by the vertical current. 



Under suitable conditions, the phenomenon of rotation is definite, 

 conspicuous, and strong, and is usually more powerful with a tubular 

 electro-magnet than with a voltaic coil alone. A very thin iron tube 

 weakens the effect of the coil, whilst a thick one reverses the motion 

 and makes it stronger. The system of rotations, either with a coil or 

 magnet, is also perfectly symmetrical. The directions of rotation 

 produced by a coil alone are independent of the magnetic nature of 

 the wire of the coil. Like other electro-magnetic effects, the rotations 

 are not prevented by the interposition of metallic screens, provided 



* In the full paper it is stated that " The whole of the results may be explained 

 by the well-known principles of electro-magnetism." 



