A treatise on the theory of solution including the phenomena of electrolysis . lution of gas. The platinized plates obtained by this methodhave very large effective surfaces, and are quite satisfactory forthe examination of strong solutions. They have the power, how-ever, of absorbing a certain amount of salt from the solutionsand of giving some of it up again when water or a more dilutesolution is placed in the cell. The investigation of very dilutesolutions, hereby made difficult, has been successfully carriedout by first platinizing the electrodes and then heating themto redness. This proce
A treatise on the theory of solution including the phenomena of electrolysis . lution of gas. The platinized plates obtained by this methodhave very large effective surfaces, and are quite satisfactory forthe examination of strong solutions. They have the power, how-ever, of absorbing a certain amount of salt from the solutionsand of giving some of it up again when water or a more dilutesolution is placed in the cell. The investigation of very dilutesolutions, hereby made difficult, has been successfully carriedout by first platinizing the electrodes and then heating themto redness. This process gives a gray surface which has enougharea to prevent polarization from interfering with the results,while it does not absorb any appreciable quantity of salt\Various causes of disturbance must be taken into account oreliminated by adjustment of the arrangements ; both the self-induction of the circuit^ and its electrostatic capacity- maybecome appreciable. The most usual arrangement of apparatus is shown diagi-am-matically in Fig. 47. The metre bridge is adjusted till no. Fig. 47. sound is heard in the telephone, when the well-known relationbetween the resistances of the four arms of the bridge holdsgood. 1 Whetham, Phil. Tram. A, cxciv. 329 (1900). 2 Encijcl. Brit., Art. Electricity, or Report, 1886, 384. Chaperon, Compt. Rend, cviii. 799 (1889), and Kohlrausch, Zeits. XV. 126 (1894). CH. IX] CONDUCTIVITY OF ELECTROLYTES 201 The telephone is not a very pleasant instrument to use inthis way, and a modification of the method, used by MacGregor*,Fitzpatrick* and the present writer-, is more rapid and alsomore accurate. The current from one or more dry cells is led toan ebonite drum, turned by a hand-wheel and cord, on whichare fixed brass strips with wire brushes touching them in sucha manner that the current is reversed several times in eachrevolution. The wires from the drum are connected with anordinary resistance box in the same way as the battery wires of
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