1824.] Conductors when transmuting the Electric Current. 28 J. 



under acids, 8cc. with metallic wires, the effects are not the same. 

 The contact of copper, for instance, produces an immediate, 

 and even strong radiating current from the point of contact 

 instead of to it, and this ceases the moment the contact becomes 

 perfect by amalgamation, and cannot be renewed but by cutting 

 off the amalgamated end, and making; afresh contact. 



45. When mercury is electrified in contact with the posi- 

 tive pole under certain metallic solutions (nitrate of copper for 

 instance), and the circuit broken, removing both wires, the 

 current continues feebly for some time after the electric power 

 is withdrawn, in the same direction, viz. from the point (z) 

 opposite to the negative pole. By degrees, it grows more 

 forcible, and a film formed during the electrisation is swept 

 along to the point (c) opposite the former position of the positive 

 wire, where it accumulates, leaving at length, the portion of the 

 surface at z quite bright. As soon as this happens, the currents 

 increase considerably in strength, and radiate with great violence 

 from the point z. This spontaneous action continues often for 

 a long while. If the negative pole be made to act in succession, 

 opposite to two points z, z', of the mercury, and be then quickly 

 withdrawn and the circuit broken, both these points become 

 centres, from which spontaneous currents radiate simultaneously 

 in all directions. If the negative pole be made to act vertically 

 over a large flat surface, when the circuit is broken, a violent 

 spontaneous radiation emanates from the point immediately 

 below the place where it was situated. 



46. If the wires be only withdrawn so as to complete the 

 circuit in the liquid, the film formed during the contact of the 

 positive pole is swept to the point c, opposite that pole ; and a 

 violent current is established, radiating from z to c. If this be 

 suffered to continue some time, and the circuit be then broken, 

 the motion continues as if the electricity still passed ; but if the 

 mercury be agitated, so as to break the crust collected ate, the 

 regularity of the motion is disturbed : the surface of the mercury 

 is thrown into a kind of filtration, owing to an immense hutEtbeo 

 of minute and very rapid vortices ; and it is not till after some 

 time that a regular and uniform direction of the currents is 

 re-established. 



47. These phenomena demonstrate the existence of a system 

 of currents radiating towards every molecule of the crust on the 

 surface. In consequence of this, so long as the latter is broken 

 up into small portions and distributed over the whole surface, 

 the currents are irregular and undecided ; but as soon as these 

 portions begin to be swept together and collected, they assume 

 a uniform direction, viz. towards that part where, from contact 

 of the vessel or other cause, they meet with no counter currents 

 to oppose them. In what manner the crust acts is however still 



