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 of hydrogen, and the acid radicle SO4, which, with water, gives H2SO4 and oxygen. In order to confirm this, Daniell filled two voltameters, A and B (Fig. 26), one {A) with a solution of sulphuric acid, the other {B) with a solution of sodium sulphate, and cooducted a current through both. In both voltameters oxygen and hydrogen were evolved, and the same quantity of the corresponding gases in each, Le. = d, and H = Hi.

It was further found that in the voltameter containing the sodium sul- phate solution there was an equivalent quantity of sodium hydroxide at the negative pole, and a corresponding quan- ^^^ 26.

tity of sulphuric acid at the positive. occurred as ions — the same quantity of electricity should have loosened double as many valencies (those of water and of sodium sulphate) in the voltameter jS as in voltameter A (only the valencies of water). This is not in agreement with Faraday's law, or the law must be considerably modified and receive a particular formulation for the salts containing metals which decompose water. If no water is present, as when fused salts are employed, the metals, and not the oxides, are obtained. The later investigations of Hittorf and Kohlrausch on the migration of the ions and the conductivity of electrolytes have proved that Daniell's view is the only tenable one.

Much discussion of the topic has led to the conclusion that, in electrolytes, the hydrogen, the metals, or the radicles, such as ammonium (NH4), methylammonium (CHsNHs), phenylammonium (GeHsNHs), uranyl (UO2), etc., which can replace a metal, form the positive ions ; and the rest of the in nitrates, CI in chlorides, forms the negative ion.

It was believed for a long time that in electrolytically conducting substances, besides the electricity transportation performed by the ions of the electrolyte, another sort of

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