DESCRIPTION OF THE PHENOMENON. 9 



after this elliptical bulging is effected ; but now, if the negative wire is cautiously raised 

 from its position, so as to be just out of contact with the surface of the metal, the mer- 

 cury is immediately convulsed, and its whole surface covered with circular waves. On 

 lowering the negative wire to its former position, and advancing the positive, the mo- 

 ment it comes to the edge of the mercurial ellipsoid, the most intense convulsions are 

 produced, which increase until contact of the mercury and wire is obtained. 3d. If the 

 two wires form a kind of triangle with the globule, it turns upon itself. 



22. At the same time that these movements are going on, the surface of the water 

 is ploughed by gentle currents, exactly resembling those produced by a breath from a 

 blowpipe, directed slantingly across the surface. 



23. In proceeding to give an explanation of these motions, I shall not follow the an- 

 alytical course of experiment used in my researches, but commence with those princi- 

 ples on which a true explanation is founded. 



24. It has long been known that the elements of compound substances were held 

 together in virtue of an affinity among themselves. Sir H. Davy, Berzelius, and other 

 chemists, were led to suspect that this was due to the electric condition of those ele- 

 ments, and pursuing this hypothesis in its details, several brilliant discoveries were made, 

 which ultimately changed the face of the science. Apart, however, from all hypothet- 

 ical reasoning, it was found that the poles of a voltaic battery had the power of influ- 

 encing the atomic constitution of bodies, so as to be able to hold all chemical combi- 

 nation under control. This remarkable effect was imputed to the electrical attraction 

 and repulsion of the battery ; but a battery which is competent to the rapid decompo- 

 sition of water, and even the reduction of potash, is found to give exceedingly faint 

 traces of any electro-dynamic effect, being unable to cause the divergence of a delicate 

 gold leaf electrometer, or affect the indications of a torsion balance. In the course of 

 certain experiments, I had occasion to notice that this effect, as to intensity, is entirely 

 regulated by the medium in w y hich the experiment is made ; as, for instance, a thin 

 lamina of air or gaseous matter is nearly a perfect non-conductor to electricity of low 

 intensity, but a mass of water offers no such resistance. I hoped, therefore, that though 

 I might not be able to exhibit the attraction of a polar wire for a suspended needle in 

 the Coulomb balance, such an effect might ensue if the experiment was made with the 

 apparatus plunged in another atmosphere, the conducting power of which differed from 

 that in which we live. For the conducting power of a medium has no relation either 

 to its cohesion or its chemical properties, and it did not appear improbable that one 

 might be found, which, though it should not interfere with the freedom of motion of a 

 wire plunged in it, its conducting power, in relation to electricities of very low in- 

 tensity, might exhibit those effects in a more elevated point of view. 



25. To illustrate this reasoning, I took a platina wire, a c (fig. 6, pi. 1), two inches 

 in length, and suspended it by a raw silk thread from a stand, b b, into a vessel filled 

 with acidulated water, as high as d d. The needle was so arranged that when it hung 

 with freedom, it was about one fourth of an inch distant from the extremities of two plati- 

 na-pointed wires, p n, which entered the vessel on opposite sides, and could be made to 

 communicate at will with the opposite poles of a battery. Now the wire p being pos- 



B 



