It was the precise statements in Demonferrand’s Manuel, agreeing as they did with the expression in M. De la Rive’s paper, (which, however, I now understand as only meaning that when the inducing current was changed, the motion of the mobile circle changed also,) and not in discordance with anything expressed by M. Ampere himself where he speaks of the experiment, which made me conclude, when I wrote the paper, that what I wrote was really his avowed opinion; and when the Number of the Lycee referred to appeared, which was before my paper was printed, it could excite no suspicion that I was in error.

Hence the mistake into which I unwittingly fell.  I am proud to correct it and do full justice to the acuteness and accuracy which, as far as I can understand the subjects, M. Ampere carries into all the branches of philosophy which he investigates.

Finally, my note to (79.) says that the Lycee, No. 36. “mistakes the erroneous results of MM.  Fresnel and Ampere for true ones,” &c. &c.  In calling M. Ampere’s results erroneous, I spoke of the results described in, and referred to by the Lycee itself; but now that the expression of the direction of the induced current is to be separated, the term erroneous ought no longer to be attached to them.

April 29, 1833. 
M.F.]

FOURTH SERIES.

S 9. On a new Law of Electric Conduction. S 10. On Conducting Power generally.

Received April 24,—­Read May 23, 1833.

S 9. On a new Law of Electric Conduction.[A]

  [A] In reference to this law see further considerations at 910. 1358.
  1705.—­Dec. 1838.

380.  It was during the progress of investigations relating to electro-chemical decomposition, which I still have to submit to the Royal Society, that I encountered effects due to a very general law of electric conduction not hitherto recognised; and though they prevented me from obtaining the condition I sought for, they afforded abundant compensation for the momentary disappointment, by the new and important interest which they gave to an extensive part of electrical science.

381.  I was working with ice, and the solids resulting from the freezing of solutions, arranged either as barriers across a substance to be decomposed, or as the actual poles of a voltaic battery, that I might trace and catch certain elements in their transit, when I was suddenly stopped in my progress by finding that ice was in such circumstances a non-conductor of electricity; and that as soon as a thin film of it was interposed, in the circuit of a very powerful voltaic battery, the transmission of electricity was prevented, and all decomposition ceased.

382.  At first the experiments were made with common ice, during the cold freezing weather of the latter end of January 1833; but the results were fallacious, from the imperfection of the arrangements, and the following more unexceptionable form of experiment was adopted.