THE discovery of the polarization of R6ntgen rays was made after a consideration of the ether pulse theory: for this theory led investigators to expect a greater intensity of the rays in a direction at right angles to the cathode stream than in the direction of that stream. C.G. Barkla, t from a series of experiments on secondary rays concluded that the primary beam is partially polarized. H. Haga, 2 by use of the photographic method, decided that no polarization of the primary rays exists; but J. Herweg, s by use of the same method, came to, an opposite conclusion.
W. R. Ham, 4 by use of the ionization method and direct experiments on the primary rays, not only showed that the intensity of the rays is a maximum in a direction at right angles to the cathode stream, but that the intensity decreases symmetrically on either side of this plane.
Dr. Ham's experiments were made o~ R6ntgen rays from an anticathode of lead. From his data we should expect polarization of rays from other metals. Also from his results on the absorption of these Pays by silver and tin we should think that there is a difference in the polarization of rays from silver as compared with those from lead and that those from silver are polarized to a greater extent.
Therefore the aim of the following investigations has been,--I. To learn if the rays from silver be polarized. 2. To learn if the polarization differ from that of the rays from lead, 3. and if so, to what extent and in what manner.