28 _ Foltaic Induction. 
rotation r 7, rr’, of these induced voltaic currents, lie accurately 
within those of R R, which give the particle, a, its magnetic power 5 
and hence, from position alone, they are capable of arising from mag- 
netic induction, and are more probable to act as a cause of the vol- 
taic circulation. I shall now proceed to show in what manner this 
may be accomplished. 
In doing so, I deem it unnecessary to discuss the question 
which may arise, whether copper and other unmagnetic metals 
are capable of receiving magnetism by induction. All these bod- 
ies, when acting as voltaic elements, not only generate, but trans- 
mit with ease both the magnetic forces; and we possess the best 
evidence, derived from the phenomena of thermo electricity, that 
circumstances connected with a mere change of temperature, and 
unaided, by any thing like chemical action, are fully sufficient for the 
developement. If, moreover, as I think will appear probable from 
the view which I propose to take, magnetic induction be the cause 
of unmagnetic metals rotating under the influence of strong magnets, 
we shall be disposed to admit the possibility of effecting the same op- 
eration upon other bodies than the metals, since Arago detected vol- 
taic currents under like circumstances, in revolving glass, resin and 
gaseous matter. One circumstance must be remembered, whatever 
value be attached to the conclusions of this enquiry. No magnetic 
rotation ever occurs, if the substance operated upon be a bad con- 
ductor of electricity ; and, accordingly, though magnetic induction 
should take place, we cannot expect a voltaic current to result when 
the peculiar cohesion or other physical condition of the matter, op- 
poses its circulation. Arago’s results, just noticed, have been ques- 
tioned by others; but their complete rejection would not affect the 
question under consideration. 
I shall proceed, therefore, upon the sapien, that all bodies. 
possess an unlimited amount of neutralized magnetic forces, capable 
of being liberated by the ordinary process Le induction; and that, 
when the substance furnishing them is a good conductor of electri- 
city, they not only revolve in circles around the component particles, 
but distribute themselves, laterally, so as to create a voltaic current. 
These magnetic circles become firmly established in a few bodies 
only, such as steel, loadstone, &c. ‘The cause of this perpetual ro- 
tation is not apparent, but however we may explain the phenomenon, 
the difficulty will certainly not be greater than that which arises from 
the supposition of a perpetual voltasc current around the same par- 
