Hermann's phenomenon / by G.S. Walpole.

  • Walpole, George Stanley.
Date:
[1914?]
Catalogue details

Licence: In copyright

Credit: Hermann's phenomenon / by G.S. Walpole. Source: Wellcome Collection.

    9/20 page 140
    position of the region in which a change of reaction is observed, and the actual titration of the amounts of acid and alkali developed, will he given later. 1st Series of Experiments. The amounts of acid and alkali liberated bear no relation to the amount of current passed.—Using as “middle fluid5’ any sodium chloride solution from O'Ol per cent, to 5 per cent., the amounts of acid and alkali obtained at the boundaries were the same, as nearly as could be judged, as long as the “ side tube fluids ” were distilled water. Also, using 5-per¬ cent. sodium chloride as “ middle fluid ” and as “ side tube fluid ” a 0'05-per- cent. solution of the same salt the result was still the same, though of course the current passed was many hundred times greater in this case. In fact, the amounts of acid and alkali liberated at 100 volts in four hours were independent of the concentrations of the “middle fluid” and “side tube fluid” as long as the former conducted electricity at least 100 times as well as the latter. To avoid heat liberation and subsequent convection currents the “ side tube fluid ” was never more concentrated than 0'05 per cent. 2nd Series. The acid, no matter what neutral salt be used, is always liberated inhere the current passes from the more dilute to the more concentratedl solution ; the alkali is always liberated where the current passes from the concentratedl solution to that more dilute.—In this series of experiments a number of neutral salts were examined. Five-per-cent, solutions were used as “ middle fluid ” ; the same solutions 100 times diluted were taken to fill the <£ side tubes.” In all cases acid was found at the left and alkali at the right boundary. The neutral salts chosen were examples cited of the following groups (a) Those whose anion and cation have approximately equal migration velocities, e.y., KC1, KI. Those whose anion is the faster ion, e.y., MgSCh, K2SO4, Nad, (0 AffNO;. (c) Those whose cation is the faster ion, e.y., KCIO3. (cl) Those whose anion migration ratio increases with dilution, e.y., MgS04, Nad, KOI, KI. (e) Those whose anion migration ratio decreases with dilution, e.y., AgNOa. 3rd Series. Other conditions beiny the same, a constant amount oj acid and cdkali is liberated, no matter what neutral salt be used.—The individual experi¬ ments of the second series above were done in pairs. Two neutral salts were taken, and the 5-per-cent, and 0‘05-per-cent, solutions of each prepared from the same sample of distilled water. They were filled into two similar trans¬ port apparatus, and connected to the same 115 D.C. main in parallel for the
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