On certain motions produced in fluid conductors , &c. 163 
It is only when liquids which conduct well are used to form 
the circuit, that they become regular, and can be studied at 
leisure under the influence of moderate electric energies. 
3. If a quantity of very pure and perfectly clean mercury, 
free from the slightest superficial film, be placed in a Wedge- 
wood-ware evaporating basin ( which must also be scrupu- 
lously clean), and covered to the depth of about a quarter of 
an inch with concentrated sulphuric acid, and the extremities 
of two wires of platina in connexion with the poles of a Vol- 
taic* apparatus be immersed in the acid only on opposite sides 
of the mercury, but not in contact with it ; immediately a 
rapid circulation will be seen to take place in the acid, owing 
to a violent current which establishes itself between the two 
wires, setting directly across the mercury in a direction from 
the negative (or zinc) towards the positive (or copper) pole. 
This current is kept up steadily, and without any change in 
its direction or force so long as the pile remains in activity, 
and only flags, and at length ceases, when its energy is 
quite exhausted. The mercury is not sensibly tarnished or 
otherwise acted on, and, after the experiment, is found to 
have undergone no change ; nor is the acid sensibly altered, 
with the exception of the trifling portion decomposed, and a 
minute quantity of mercury taken up. 
4. If we examine the phaenomena more attentively, we shall 
observe that the particles of the acid in immediate contact 
with the mercury , are those which move most actively, being 
* The battery I employed in this and the subsequent experiments (unless where 
the contrary is expressed), consisted of ten pairs of single plates, each of fourteen 
square inches in surface, excited by mixed nitric and sulphuric acids much 
diluted. 
