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considers the oxidation-reduction potentials of the two systems involved.1 From a dissertation submitted by Philena Young to the Graduate School of the University of Michigan in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry.

Salstrom's data upon activities was obtained in the case of silver bromide in lithium bromide and sodium bromide. In the case of lithium and potassium salts the deviation from ideality seemed slightly greater for the chlorides than for the bromides.6. The activity coefficients of various salts other than chlorides and bromides might be determined by measurements of e. m. f. in cells otherwise similar to those employed in this research.7. An interpretation of Gtinther-Schulze's observations upon the diffusion of silver ion into glass from fused silver halides was offered.

THEmost exact methods at the present time for chromium involve the direct titration of the chromic acid, obtained from a persulfate or similar oxidation, with standard ferrous sulfate, The end point may be determined either potentiometrically or with an oxidation-reduction indicator.. If vanadium is present in the steel, as is very often the case, vanadic acid is formed in the oxidation process, and this substance is titrated along with the chromic acid. It is necessary, then, to determine vanadium before the percentage of chromium can be estimated.

the glass electrode is applicable. Furthermore we have observed that glass No. 6 shows steadier potentials in alkaline solution than any other that we have worked with. A comparison of two glasses under somewhat extreme conditions is given in the curves plotted in Fig. 4. The upper curve indicates the variation of the potential with time of the soft commercial glass, and the lower curve the corresponding variation of glass No. 6. It will be seen that the readings of the latter are roughly constant even in these strongly alkaline solutions.Hughes2 has shown, however, that these deviations in alkaline solutions depend upon the nature of the positive ions present. We have found, however, very small deviation at about Ph 13 when the base present is tetramethylammonium hydroxide; this is shown in Point C of Fig. 3. We hope to be able to present in the near future a theory explaining these deviations.