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ON THE CHANGE OF VOLUME WHICH ACCOMPANIES THE GALVANIC DEPOSITION OF A
METAL.

By M. E. BOUTY.


In previous notes I have established, first, that the galvanic
depositions experience a change of volume, from which there results a
pressure exercised on the mould which receives them; second, that the
Peltier phenomenon is produced at the surface of contact of an electrode
and of an electrolyte. Fresh observations have caused me to believe that
the two phenomena are connected, and that the first is a consequence
of the second. The Peltier effect can clearly be proved when the
electrolysis is not interfered with by energetic secondary actions, and
particularly with the sulphate and nitrate of copper, the sulphate and
chloride of zinc, and the sulphate and chloride of cadmium. For any one
of these salts it is possible to determine a value, I, of the intensity
of the current which produces the metallic deposit such that, for all
the higher intensities the electrode becomes heated, and such that it
becomes cold for less intensities. I will designate this intensity, I,
under the name of _neutral point of temperatures_.

The new fact which I have observed is, that in the electrolysis of the
same salts it is always possible to lower the intensity of the current