WHEN an electric field is impressed between parallel plates immersed in carbon bisulphide it is found that the liquid becomes doubly refracting. This phenomenon, called the Kerr Effect, has been known for a long time and has been used in various ways in optical investigations involving very short time intervals. Recently one of the authors i made use of a modification of the method of Abraham and Lemoine 2 in a study of the relative times of appearance of spectrum lines in spark discharges and later 3 carried out some experiments which indicated that in some liquids the Kerr effect lags behind a rapidly changing electric field. During the past year the authors 4 studied the photo-electric effects produced by short flashes of light and also investigated in further detail the apparent lags of the Kerr effect in various liquids. The present work is a continuation of these experiments.
EXPEmMENTAL ARRANGEMENT AND THEORY OF THE METHOD.
The experimental arrangement for the study of lags in the Kerr effect and for the production of short light flashes centers around two Kerr cells, K1 and K2, placed between crossed Nicol prisms, N1 and N2. The normals to the surfaces of the plates of one cell are at right angles to the normals to the surfaces of the other pair of plates and both sets of normals make angles of forty-five degrees with the electric vector of the plane polarized light passing between the plates from N1.