A galvanic cell study of the Ca+CaC12 system is reported. By proper allowance for electronic conduction in the electrolyte phase, the thermodynamic properties have been determined. These data are in good agreement with a vapour pressure study and phase diagram determinations. A model is proposed based upon non-stoichiometric compound theory involving an electron pair exchange equilibrium (Ca2)2+ +2CaZ+ + e2 at low Ca concentration. As the Ca concentration approaches saturation, electron pairs are increasingly dissociated and the solution may be described by the equilibrium (Ca2)*+ +2Ca2+ + 2e.

The principal constituents in molten solutions of calcium carbide in calcium chloride have been determined. The analytical results were generally within order of magnitude agreement with calculations from thermodynamic data based upon a model in which the calciumcarbideis thought to be dissociated according to the equationOn a Btabli la nature des principaux constituants des solutions fondues de carbure de calcium dans le chlorure de calcium. Les rdsultats analytiques sont g6nCralement en accord tt I'intQieur d'une ordre de grandeur-avec les donnks thermodynamiques basks sur un modkle dans lequel on croyait que le carbure de calcium est dissociB suivant 1'Bquation

The galvanic cell Fe[C](s) I CaC2, CaCl2(,) [ Cos)has been studied in detail in the temperature range 800~176 using electrodes containing carbon at different activity levels. Calcium metal, the electroactive species, is present in the electrolyte by virtue of the heterogeneous equilibrium CaC2(soln) ~ Ca(sore) + 2C(electvode or~ruclble)

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The authors of the above paper thank Professor Carl Wagner of the Max Planck Institut fur biophysikalische Chemie for pointing out an error in the paper.Specifically, Professor Wagner states that to derive eqn (1) (p. 1088) no assumptions regarding individual species in the Ca+CaC12 melt are needed. The phrase " to consist " is therefore misleading. It is necessary however to state the choice of a reference component for the definition of transference numbers and to state how transference numbers are defined.Thus for the C1-ion as the reference component, tcl-= 0, and one has the supplementarywith symbols as previously defined. References in the paper to the term in dpGClz (p. 1088 lines 13 and 14, p. 1091 lines 6 to 9) should be disregarded. The bulk of the calculations and the conclusions are unaffected by this error.