The Effect of Pressure on the Electrical Conductance of Salt Solutions in Water

New data are presented for the change with pressure of the equivalent conductance of the following 1/100 normal salt solutions in water: at 30^∘{}C, HCl, LiCl, NaCl, KCl, RbCl, CsCl, NaF, NaBr, NaI, Na₂SO₄, NaC₂{H}₃O₂, CaCl₂, BaCl₂, ThCl₄, K₃Fe(CN)₆, K₄Fe(CN)₆; and at 75^∘{}C, all the above solutions excepting NaF and ThCl₄. The pressure range at 30^∘{}C is 1-10,000 kg/cm², and at 75^∘{}C it is 1-11,000 kg/cm². It is pointed out that the observed maxima in the equivalent conductance can not be entirely caused by a change in the degree of dissociation of the ions with pressure. By using a well-known expression for the equivalent conductance at infinite dilution, and also by using the Debye-H\"ucklel formula, it is shown in each case that there must be a large change in the diameters of the ions due to the pressure if the theory is to agree with the data.