Fan. 19, 1882] 
s dedicated to the memory of the late Prof. Kessler.—Zoolo- 
sists will find valuable contributions to the knowledge of Russian 
zo0-geography in the researches of MM, Khlebnikoff, Nikolsky, 
and Lavroff as to the fauna of the governments of Novgorod, 
Astrakhan, and Kaluga, published in vol. xi. of these Memoirs. 
SOCIETIES AND ACADEMIES 
LONDON 
Royal Society, December 15, 1881.—‘‘ On some Effects of 
Transmitting Electrical Currents through Magnetised Electro- 
lytes.” By Dr. G. Gore, F.R.S. 
This communication treats of a class of electro-magnetic 
rotations observed and examined by the author. The rotations 
are produced in liquids by means of axial electric currents either 
in the interior of vertical magnets, electric or permanent, or near 
the poles of such magnets; and differ from rotations previously 
produced in liquids placed in those positions, by the absence of 
radial currents, to the influence of which rotations in the interior 
of hollow magnets have hitherto been ascribed. In the full 
paper it is stated that ‘‘the whole of the results may be ex- 
plained by the well-known principles of electro-magnetism.” 
It is here shown that a column of an electrolyte placed under 
similar conditions to an iron wire or rod when subjected to 
electro-magnetic torsion (¢.e. inclosed 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 solution. 
The rotations produced in liquids by means of axial currents 
are opposite in direction at the two ends of the magnet-tube, 
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 anelectro or a permanent magnet, oppo- 
site to those produced by a voltaic solenoid; 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 solenoid 
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 the portion of the 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 con- 
taining vessel, but upon the adjacent magnetised body; the 
rotation of the liquid is confined to the portion traversed by the 
vertical current, 
Under suitable conditions the phenomenon of rotation is defi- 
nite, 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 rota- 
tions, either with a coil or magnet, is also perfectly symmetrical. 
The directions of rotation produced by a coil alone are inde- 
pendent 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 they are non- 
magnetic. The rotations may be easily produced by the aid of 
a current from three or four Grove’s elements, especially if 
permanent bar-magnets are used instead of a voltaic coil. The 
rotations by means of vertical currents in the liquid may be 
produced by the influence of coils or magnets, either above or 
below the liquid, 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 directions of rotation as a coil placed either above, below, 
or around it. The direction of rotation produced in a liquid 
above a coil by an wpward current in the liquid agrees with that 
produced by a radial centripetal one. 
NATURE 
283 
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 pre- 
sence 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 magnet as with a coil, In this respect the motion 
produced by radial currents differs from that produced by vertical 
ones. With each electrode, diverging currents produce dextro- 
and converging ones lzvo-rotation. The rotation of the elec- 
trodes by means of radial currents appears to be independent of 
that produced in the liquid by means of vertical 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 axial current are not 
confined to liquids, but may also be produced in a solid con- 
ductor, and probably therefore with any body conveying an 
electric current or discharge. 
The directions of rotation produced in liquids by means of 
radial currents under the influence of a magnet or coil, are the 
same asin the solid electrodes, and are lzevo at all positions with 
centripetal currents and dextro with centrifugal ones, when the 
North Pole is above. 
A given direction of axial current, whether in a solid or liquid 
conductor, whether above or below a given magnetic pole, and 
whether that pole constituted the upper or lower end of a coil or 
magnet, produced the same direction of rotation. A given 
direction of radial current also, whether in the electrodes or 
electrolytes, or above or below a given pole, provided that the 
pole was not altered in position, produced the same direction of 
rotation. 
Various other phenomena, such as temporary reversals of the 
direction of rotation, successive action of the coil and iron tube, 
&c., &c., are recorded in the paper. 
With a Solenoid,—A current flowing upwards from a south to 
a north-seeking pole produces dextro rotation at the former, and 
lzevo rotation at the latter. W2th a magnet these two directions 
are reversed at all distances between the two neutral points near 
the poles of the magnets, but not beyond, The phenomena 
therefore of rotation are more complex with a magnet than with 
a solenoid. 
The reversals of direction of rotation which cecur when a 
tubular magnet is employed appear to be due to the inner surface 
of the magnet and to the position of that surface in relation to 
the current in the liquid. The direction of rotation and the 
points of reversal appear to be all independent of each other. 
The action of radial currents is more simple than that of 
axial ones, especially near the poles of a magnet. With radial 
currents, either in the liquid or electrodes, there is no reversay 
either at the centre of the magnet or coil, or at the poles or 
beyond them. 
The experiments show in a conspicuous manner the difference 
of property of the interior surface of a hollow magnet and of 
that of a solenoid having the same kind of poles at their corre- 
sponding ends. This difference of property is well known, but 
is illustrated in the paper in a new way experimentally. 
The whole of the foregoing results are illustrated by experi- 
ments, 
Mathematical Society, January 12.—S. Roberts, F.R.S., 
president, in the chair.—Dr. G. J. Allman and Mrs. Bryant were 
elected Members, and Mr. G, H. Stuart was admitted into the 
Society.—A vote of thanks was passed to the Norwegian 
Government for the present of a copy of the new edition ‘of 
Abel’s works.--The following communications were made :— 
The invariants of a certain orthogonal transformation, with 
special reference to their use in the theory of the strains and 
stresses of an elastic solid, by Mr. W. J. C. Sharp.—Some 
formulz in elliptic functions, by the Rev. M. M. U. Wilkinson. 
—Complete determination of the real foci, and of the vector 
equation, of a given ellipse with respect to any proposed point, 
by Prof. Wolstenholme.—On the calculation of symmetric 
functions, by Mr. J. Hammond. 
Royal Horticultural Society, January 10.—Hylecatus der- 
mestoides : Mr. Pascoe showed a male and a female specimen of 
this British beetle, and alluded to the report that it feeds on the 
wood-boring species, but does not itself bore the wood. Mr, 
Maclachlan remarked that it was an open question whether 
this idea were true.—Glastonbury Thorn: Dr. Masters exhi- 
bited specimens of this plant received from Mr, Boscawen, 
