fluid conductors when transmitting the electric current. 17 5 
repelled from c. The positive pole being held at some dis- 
tance, and the negative directly over the surface, any scum 
or impurity on the mercury was observed to collect directly 
under it, in a small circular spot, following exactly its mo- 
tions ; and when this was cleared away, the fluid metal was 
violently thrown up towards the wire in a jet of two or three 
tenths of an inch in height. 
2 1 . The mercury was now brought into contact with the 
positive wire. Visible oxidation did not commence on its sur- 
face for a long while, during which time violent currents still 
continued to radiate in all directions from the wire and towards 
the point % (or in a direction opposite to what they would 
have taken in untouched mercury). By degrees, however, 
a counter-radiation commenced opposite to the negative pole, 
whose sphere was at first very limited, but gradually ex- 
tended, producing a zone of equilibrium, which advanced 
rapidly towards the positive wire, and at length attained it. 
The instant this took place, the oxidation of the mercury 
commenced at z, and speedily extended over the whole sur- 
face, forming a thick crust. 
22. If the contact of the positive pole was continued long 
enough, the mercury, on cleansing it from its coat, was found 
reduced to its former state, as if freshly introduced ; but if 
broken as soon as the crust was fully formed, a radiation from 
the negative wire was produced, and the crust broken up and 
swept by it to c, where it collected, and was hurried off. But 
the moment this was done, and the surface of the mercury 
had become bright throughout, it stopped for an instant, and 
immediately a violent revulsion took place and a powerful 
current radiated from c, that from z being annihilated. 
