the Repulsion of a Reetilinear Electrical Current on itself. 249 
moveable wire upon mercury, he placed it upon one of the arms of 
a delicate torsion balance. ‘The ends of the moveable wire were 
made to bear slightly against the extremes of the two wires in 
connexion with the poles of the pile. When the current was 
established, the moveable wire placed upon the balance was 
attracted by the wires proceeding from the pile, and not repelled 
as in the case of Ampére’s experiment; and the stronger the 
current, and the more complete the contact of the ends of the 
wires, the greater the attraction was found to be. 
There is one objection which may be urged against the con- 
clusiveness of the experiment. It is well known that the ends 
of two wires connecting the poles of a voltaic pile before they 
are brought into contact, are statically charged, the one with 
positive, and the other with negative electricity, the intensity of 
the charge depending upon the force of the pile. Now it is evi- 
dent that these two wires being charged with different electri- 
cities, must attract each other. It is evident also that, however 
close the two ends of the wires may be brought together, unless 
they are in absolute contact in every part, a thing impossible 
without soldering the ends together, the current will not pass 
from the extremity of the one wire to that of the other through the 
intermediate space, which is almost non-conducting, unless there 
is an excess of positive electricity on the one wire and of negative 
on the other; and the more.so, considering the low tension of 
voltaic electricity. This being the case, the ends of the conduct- 
ing wire and those of the moveable branch will always be charged 
with different quantities of electricity, and hence attraction will 
be the consequence; yet one would suppose that, unless the 
current is in reality self-attractive, the attraction arising from 
this cause would not be able to overcome the repulsion which 
must ensue from the action of angular currents just considered. 
There is one objection to the common notion that the parts of 
a rectilinear current are mutually repulsive, that I have never 
seen adduced, which isasfoliows: It results from a law of Ohm, 
which has been confirmed experimentally by Kohlrausch, that in 
the conductor connecting the poles of a voltaic pile, while the 
current is circulating, different sections of the conductor are dif- 
ferently charged. In any part of the conductor whatever, a 
section taken towards the positive pole is always positive in rela- 
tion to a section taken towards the negative pole; and vice 
versa, a section towards the negative pole is negative in relation 
to any section taken towards the positive pole. It follows from 
this that the different sections of the current must attract each 
other. 
The difference of the tension of any two sections depends upon 
the resistance to conduction ; that is to say, the force by which 
