Lessons in elementary physics / by Balfour Stewart.

  • Balfour Stewart
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: Lessons in elementary physics / by Balfour Stewart. Source: Wellcome Collection.

    462/502 page 442
    at the negative pole electro-positive. Oxygen is the most electro-negative element, and potassium the most electro- positive. 433. Elements only Appear at the Poles.—If we study the chemical action of the current, as represented in Fig. 136, we naturally ask. How is it that the oxygen appears at the one wire, and the hydrogen at the other ? Is the oxygen of each particle decomposed carried bodily to the one pole and the hydrogen to the other ? In order to test to what extent this will hold, Davy performed the following experiment. He took three glasses. A, B, c (Fig. 137)) into the first of which he put a solution of sodium sulphate into the second syrup of violets, while the third contained pure water. These three vessels he connected together by moistened threads of asbestos. The current was then made to go, in the figure, from C Fig. 137. to A. The consequence was that in time the sodium sul- phate was decomposed, the alkali being left in A, while the acid was found in c. When the current was reversed, the acid was found in A, and the alkali in c ; but in neither case was the syrup of violets affected by the passage through it of the acid or the alkali. 434. Tlie Hypothesis of Grotthuss.—Grotthuss has imagined an hypothesis which may explain this peculi.ar action of the current. In order to simplify conception, let u's suppose that we are decompo.sing water. Then he supposes that the oxygen of the molecule of water next the positive pole will place it.self next that pole, as in Fig. 138, and that the whole row of particles between the two poles will follow,
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