Effect of an Electric Field on the Viscosity of Liquids

We are sorry that the interesting paper of Sokolow and Sossinski, referred to in the above letter, escaped our notice, and we are very glad that our attention has now been directed to it. We agree that in it the authors clearly established a large effect of electric field on the apparent viscosity of polar liquids, and that the effect is accompanied by the passage of an electric current, both of which facts are among our observations. We think, however, that the method which Sokolow and Sossinski used, namely, a capillary of square cross-section, with the field applied to two opposite sides, is less precise than our disposition: we used a capillary of rectangular cross-section, with side ratio 1 to 50, and the potential applied to the long sides. In our case the field is uniform; in the other case, owing to differences of dielectric constant between liquid and glass, it is far from being homogeneous, which may be one of the causes of certain discrepancies which we have noted.