Stalagmometric titrations.
End-point detection in some precipitation titrations is achieved by measurement of the surface tension between mercury and the solution ("stalagmometric" titration). The drop-time of a polarographic dropping mercury electrode in open circuit is plotted against volume of surface-active titrant added, and shows a break or a peak at the end-point. The stalagmometric titration of sodium tetraphenylborate with Zephiramine (tetradecyldimethylbenzylammonium chloride) was satisfactory and made possible the determination of potassium by back-titration. Potassium was also titrated directly with tetraphenylborate and with calcium dipicrylaminate. Sodium dodecylbenzenesulphonate was titrated directly with Zephiramine and the results were compared with those obtained by the p-toluidine method and Epton's method.
Kambara
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Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Japan.
Kiba
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