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THE ELECTRO-TONIC STATE. 141 
66. All metals take on the peculiar state. This is proved in the preceding 
experiments with copper and iron (9.), and with gold, silver, tin, lead, zinc, 
antimony, bismuth, mercury, See. by experiments to be described in the fourth 
part (132.), admitting of easy application. With regard to iron, the experi¬ 
ments prove the thorough and remarkable independence of these phenomena 
of induction, and the ordinary magnetical appearances of that metal. 
67- This state is altogether the effect of the induction exerted, and ceases 
as soon as the inductive force is removed. It is the same state, whether pro¬ 
duced by the collateral passage of voltaic currents (26.), or the formation of a 
magnet (34. 36.), or the mere approximation of a magnet (39. 50.) ; and is a 
strong proof in addition to those advanced by M. Ampere, of the identity of 
the agents concerned in these several operations. It probably occurs, mo¬ 
mentarily, during the passage of the common electric spark (24.), and may 
perhaps be obtained hereafter in bad conductors by weak electrical currents 
or other means (74. 76.). 
68. The state appears to be instantly assumed (12.), requiring hardly a sensible 
portion of time for that purpose. The difference of time between volta-elec- 
tric and magneto-electric induction, rendered evident by the galvanometer 
(59.), may probably be thus explained. When a voltaic current is sent 
through one of two parallel wires, as those of the hollow helix (34.), a current 
is produced in the other wire, as brief in its continuance as the time required 
for a single action of this kind, and Avhich. by experiment, is found to be in¬ 
appreciably small. The action will seem still more instantaneous, because, as 
there is an accumulation of power in the poles of the battery before contact, 
the first rush of electricity in the wire of communication is greater than that 
sustained after the contact is completed; the wire of induction becomes at the 
moment electro-tonic to an equivalent degree, which the moment after sinks 
to the state in which the continuous current can sustain it, but in sinking 
causes an opposite induced current to that at first produced. The consequence 
is, that the first induced wave of electricity more resembles that from the dis¬ 
charge of an electric jar, than it otherwise would do. 
69. But when the iron cylinder is put into the same helix (34.), previous to 
the connexion being made with the battery, then the current from the latter 
may be considered as active in inducing innumerable currents of a similar kind 
