Page:Text-book of Electrochemistry.djvu/140

 CHAPTER IX.

Conductivity of Electroljrtes.

Horsford's Method of Determining the Resistance

(1), — The experiment is carried out in a parallel-sided trough containing a salt solution and two non-polarisable electrodes (e.g. amalgamated zinc plates in a solution of zinc sulphate), the sizes of which are almost as great as the cross section of the trough. The electric current from a battery E (Fig. 29) is led to the anode A, and passes from this through the zinc

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��sulphate solution to the cathode B. From B it passes to a movable contact, k, and returns to H along the metal wire III, The branch of the circuit between B and k contains a galvanometer ff, and the deflection of the needle of this is proportional to the current strength.

If, now, B is brought to the position denoted by Bi, the resistance in the trough is diminished, and the galvanometer needle shows a greater deflection. If k is then slid along Hi until the deflection of the galvanometer is the same as before, the total resistance in the circuit is evidently the same as originally, i.e. the resistance of the column of liquid BBi,

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