Densities of binary liquid mixtures of AlkCl + CaCl₂ and AlkCl + MgCl₂ have been measured. Molar excess volumes V^E_m of mixing are given. In the CaCl₂-system the excess volumes are always positive, while both positive and negative excess volumes are always positive, while both positive and negative excess volumes are found in the MgCl₂-systems. The excess volume curves show pronounced maxima near the composition 33 mol % MgCl₂ in the systems KCl+, RbCl+, and CsCl + MgCl₂. It is suggested that V^E_m can be separated into two principal parts. One part is positive and associated with changes in ionic interactions (the Coulomb interaction); the other part is negative and is attributed to the effect of changing the covalent bridging interaction in liquid magnesium chloride when mixing the two components. Densities of six mixtures in each of the two ternary systems NaCl + CaCl₂+ MgCl₂ and KCl + CaCl₂+ MgCl₂ have also been measured and the excess volumes determined for each mixture. These values are compared with the excess volumes calculated from the component binaries.

Densities of several binary and ternary liquid chloride mixtures of potential interest have been measured as a part of an investigation of the physicochemical properties of the magnesium chloride electrolyte for the electrowinning of magnesium.