Page:Text-book of Electrochemistry.djvu/35

 1 8 OLDER ELECTROCHEMICAL VIEWS. chap.

reducible metals in this way was later made by Buusen and his pupils.

Berzelius's Investigations. — In 1807, J. J. Berzelius, in conjunction with Baron Hisinger, published his first paper, which formed the foundation of his subsequent electro- chemical theory. These investigators came to the following conclusions : —

Neutral salts are decomposed by the electric current. In general, chemical compounds are decomposed by the current, and the constituents collect at the poles.

Combustible substances, the alkalis, and earths migrate to the negative pole; oxygen, the acids, and oxidised com- pounds' migrate to the positive pole. Thus, for example, nitrogen in ammonia goes to the negative pole, whilst in nitric acid the nitrogen goes with the oxygen to the positive pole.

The quantities of the products of decomposition are proportional to the quantities of electricity, and these are dependent upon the area of contact of the metals in the pile and on the moist conductor. Further, the quantities of substance decomposed are proportional to the electrical conductivities of the solutions.

The chemical processes taking place during an electrolysis are determined : firstly, by the affinities of the constituents to the metals of which the poles are constructed ; secondly, by the reciprocal affinities of the constituents ; and thirdly, by the cohesion (solubility) of the new compounds.

It was on these and similar conclusions drawn from experiment that Berzelius, as well as his precursor, Davy, founded their electrochemical theories.

Davjr's Electrochemical Theory. — ^Davy proved that acid and base could not be formed from pure (free firom salt) water, as had been erroneously believed. He found that l)y using pure water in a gold vessel no acid or base was produced, but where the vessel was one of gypsum, fluorspar, heavy spar, basalt, lava, or glass, partial solution of the material of which this was made took place, and the results formerly found could be explained.

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