MR. S. P. RANGANADHAM states, in NATURE of June 27, that he has obtained values for the specific susceptibility of mixtures of organic liquids which differ markedly from those obtained by us.1 It is impossible to answer Mr. Ranganadham's assertion without a full knowledge of his data, consequently we must await the publication of his results before we can reach an opinion as to the comparative value and accuracy of the two sets of values. In the meantime, however, we must justify our continued belief in the accuracy of our work. In the first place, as pointed out in our paper, the specific susceptibilities of the pure liquids used in our experiments were found, with a single exception, to be closer to Pascal's calculated values than any values hitherto published. We attribute this fact to the carefully checked purity of the material used. The susceptibility values used in plotting our curves were, in every case, obtained several times with fresh portions of the mixtures; the symmetry of the curves and the fact that they exhibit maxima in the same positions as other property-composition curves is confirmatory of the accuracy of our results.