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.

    461/502 page 441
    elements; thus water is decomposed into llie gases oxygen and hydrogen. Faraday was the first to discover the laws which regulate this action of tlie current, and he has termed decomposition by the battery Electrolysis, while the term Electrolyte has been applied to any substance which is capable of being so decomposed. The voltaic battery first enabled us to demonstrate the com- pound nature of certain substances that had previously been considered elements. Thus Davy, by a battery of 250 cells, decomposed potash Fig. 136. and soda, and showed that they contained the metals potassium and sodium. When a battery is used to decompose water, an arrangement like that in Fig. 136 is used. .‘Vt the left hand we have the positive pole, and at the right hand the negative pole of our battery, so that the progress of tlie current is from left to right. Now if we have two vessels, o and li, botli filled with water, and if p and >t be two platinum terminals of the battery entering these vessels, it will be found that if the battery is strong enough, the current will decompose the water, and that oxygen gas will appear in the vessel o, while hydrogen gas appears in H, the volume of the hydrogen being about twice as great as that of the o.\ygen. The elements which appear at the positive pole of a battery are called electro-negative elements, and those which appear
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