Limiting Mobilities of Some Monovalent Ions and the Dissociation Constant of Acetic Acid at 25°

VOGEL and Jeffery in a recent letter,¹ with the same heading as the above, have directed attention to the fact that we omitted, in our recent paper,² to mention that they have published³ different figures from ours for the liiniting mobilities of ions. Though we should, possibly, have referred to their work in that particular connexion, it was not ignored. The conductance measurements of these authors and the discrepancies between their work and ours were discussed in a paper from this Laboratory.⁴ This paper directs attention to the fact that Jeffery and Vogel used a bridge and cells which, due to parasitic currents, could readily give errors in the results. Their use of a water thermostat leads to additional errors of similar nature, as has been shown by Jones and Josephs.⁵ Jeffery and Vogel have published conductance measurements only. To obtain ion conductances transference data are necessary. In their paper they present two sets of figures for the limiting ion conductances, leaving the choice to the reader. One set is based on a limiting transference number of potassium in potassium chloride of 0.497 and the other on a value of that constant of 0.490, the latter being the result of recent work in our Laboratory.