On the basis of the classical conception of electrolytic conductance,we have derived the formula(8) which expresses the specific conductance of a solution,containing an electrolyte and a neutral complexing agent,as a function of the equivalent conductances of the complex compounds formed in solution.Since it has the same form as that of the Yatsimirskii's general formula,it could be considered as a special case of the latter. In order to verify the validity of the expression in question,we have undertaken the measurement of the specific conductances of two series of solutions,one containing hydrogen chloride and 1-naphthylamine,and the other,hydrogen chloride and aniline.The data so obtained were treated according to the above formula and gave the "pK"s of the two protonic acids formed in the solutions as 3.86 and 4.36 respectively.These figures are in fair agreement with those found by the E.M.F.method,which gave 3.92 and 4.58 respectively.