Personal Narrative Of Travels To The Equinoctial Regions Of America During The Years 1799-1804 - Volume 2 - By Alexander Von Humboldt And Aime Bonpland.
- Page 185 of 777 - First - Home
Some Anomalies, Which We Thought We Observed, Are Easily
Explained, When We Recollect That Even Metals (As Is Proved From
Their
ignition when exposed to the action of the battery) present a slight
obstacle to the passage of electricity; and
That a bad conductor
annihilates the effect, on our organs, of a feeble electric charge,
whilst it transmits to us the effect of a very strong one. The
repulsive force which zinc and silver exercise together being far
superior to that of gold and silver, I have found that when a frog,
prepared and armed with silver, is galvanized under water, the
conducting arc of zinc produces contraction as soon as one of its
extremities approaches the muscles within three lines distance; while
an arc of gold does not excite the organs, when the stratum of water
between the gold and the muscles is more than half a line thick. In
the same manner, by employing a conducting arc composed of two pieces
of zinc and silver soldered together endways; and resting, as before,
one of the extremities of the metallic circuit on the femoral nerve,
it is necessary, in order to produce contractions, to bring the other
extremity of the conductor nearer and nearer to the muscles, in
proportion as the irritability of the organs diminishes. Toward the
end of the experiment the slightest stratum of water prevents the
passage of the electrical current, and it is only by the immediate
contact of the arc with the muscles, that the contractions take place.
These effects are, however, dependent on three variable circumstances;
the energy of the electromotive apparatus, the conductibility of the
medium, and the irritability of the organs which receive the
impressions:
Enter page number
PreviousNext
Page 185 of 777
Words from 50127 to 50410
of 211397
