166. Prof. Sylvanus P. Thompson confirmed non-polarization, (_Phil. So._, June 12, ’96, and _The Electr._, Lon., June 26, ’96.) Dr. John Macintyre (_Nature_, June 24, ’96) carried on a long series of experiments with tourmaline, and also arrived at the conclusion that polarization of X-rays is practically impossible, § 97, at end. [Illustration: FROM SCIAGRAPH BY PROF. GOODSPEED, SHOWING CURVATURE OF THE RADIUS, DUE TO ARRESTED DEVELOPMENT OF THE ULNA AT ITS DISTAL EPIPHYSIS. ONE BONE SHOWN THROUGH ANOTHER. ] 167. In the same paper Prof. Thompson showed conclusively that there is a diffuse reflection of X-rays. § 81 and 103. A curious experiment consisted in his obtaining dust figures, § 36. by the discharge of an electrified body by X-rays. In another experiment he caused reflection of the rays from the surface of sodium located in a vacuum. The amount reflected was a minimum for normal incidence and increased at oblique incidence. 168. Prof. Oliver J. Lodge, F.R.S., reported in _The Electr._, Lon., June 5, ’96, further detail experiments in the line set out in § 113. He proved conclusively, as stated by the editorial in _The Electrician_, that a positive charge has increasing effect upon the ray-emitting power of the surface exposed to the cathodic radiation. 169. At Eton College, T. C. Porter (_Nature_, June 18, ’96) confirmed the experiments of others by showing that the blackened face of the thermopile connected with a very sensitive galvanometer was not influenced in any manner by X-rays. 170. Prof. William F. Magie, of Princeton, N. J., made a careful experiment in relation to diffraction. _Princeton College Bulletin_, May, ’96. The experiment would certainly prove that if X-rays are due to vibrations, the latter are of a different order from those occurring in light rays, for the slits exhibited light diffraction very well, but there was no evidence, by a widening of the image on the plate, that X-rays had been diffracted in the slightest degree. § 110 and 110_a_. 171. Prof. Haga, of Groningen University, at the suggestion of Mr. J. W. Giltay, (_Nature_, June 4, ’96,) made some very crucial tests, with numerous precautions, in reference to the action of X-rays upon selenium, and the results were so positive that they thought that a practical application could be made by using selenium for detecting X-rays, both qualitatively and quantitatively. In repeating the experiments, it must be borne in mind that one half hour or so is required for selenium to return to its former degree of ohmic resistance after being struck by light or heat or X-rays. _Total number of_ § § _to this place, 199._ ------------------------------------------------------------------------ CHAPTER XIII A FEW TYPICAL APPLICATIONS OF X-RAYS IN ANATOMY, SURGERY, DIAGNOSIS, ETC. -------