NOTES Below a dielectric constant of about 40, the curve approximates linearity, showing that the factor exp (2laDlcT) in the association constant' is now the significant variable. The slope of the linear portion gives an it value of 5.35; as seen in Figure 1, this value of it would also give values of c within experiment error and is in fact nearer to the minima of Figure 1 than 8.0. This choice of it for the range of low dielectric constants would, of course, force agreement between the values of a for both the association constant and for the long-range KU terms, but it would involve two values (8.0 for D > 50 and 5.35 for D < 50) for the parameter. For the alkali halides, we found* that one value of the parameter sufficed for the entire range. The single-ion conductance for thallium can be obtained from our value of A. = 146.195 for TIN08 in water at 25". Usings Ao(I
