Chemistry and Physics. 327 



greatly increased by the excitation of electric waves. Fessenden, 

 to whom the priority of the discovery of this receiver has been 

 awarded, believes that the action arises from an increase of heat 

 in the immediate neighborhood of the small electrode ; this 

 explanation has been found untenable. Later experiments of 

 Rothmund and Lessing show a coherer and not an anticoherer 

 effect when the electrolyte (phosphoric acid and hyperphosphor- 

 ous acid at higher temperatures), has a negative resistance tem- 

 perature coefficient. Reich believes that the action results from 

 a depolarizing effect. 



The object of Dr. Gundry's paper is to show that in a polariz- 

 able electrode, in general, as soon as we pass beyond the stage of 

 initial capacity the alternating current gives rise to an asym- 

 metry which appears as a coherer effect. His experiments were 

 conducted only with mercury electrodes on account of the more 

 definite conditions which can be obtained by their use. One 

 electrode was very small in order that it might be considered 

 unpolarizable, the other more than one thousand times greater. 

 A galvanometer in the alternating circuit showed that the cur- 

 rent, before symmetric, was rendered asymmetric by passage 

 through the cell. In other words, there was superposed on the 

 alternating current a direct current, and the production of this 

 direct current involves the existence of an asymmetry in the 

 E.M.F. of the polarization produced by the alternating current. 

 This asymmetry, the author believes, is a natural consequence of 

 the osmotic theory of electi'o motive force in general and its appli- 

 cation to polarization in particular. 



For the production of the alternating current the sine inductor 

 of Kohlrausch alternated in use with the Dolezalek alternating 

 current machine made by Siemens and Halske. An upper limit of 

 5000 alternations per second. was obtained. Experiments with a 

 platinum electrode both anodically and cathodically polarized, 

 showed that the magnitude of the direct current value varied at 

 high frequencies much less with the frequency than is the case 

 with the mercury electrode. — Phil. Mag., March, 1906, pp. 329- 

 353. j. t. 



8. Ionization by Rontgen and Cathode Rays. — This is a study 

 at Wtirzburg by J. Heeweg of various unsolved points in regard 

 to this subject. It is shown that the ionization produced by the 

 X-rays up to a temperature of 400° is independent of the tem- 

 perature ; in other words, the resulting ionization is not accom- 

 panied by a rise in temperature. It is also shown that simul- 

 taneous ionization of air by a glowing wire and the X-rays results 

 in a simple superposition of both ionizations. 



X-rays and also cathode rays produce a diminution of the dis- 

 charge potential of the Glimmentladung • the effect of the rays is 

 dependent upon the volume of gas between the electrodes and 

 the pressure. 



A theoretical discussion of the movement of electrons in a 

 combined electrostatic and magnetic field concludes the paper. — 

 Ann. der Physik, No. 2, 1906, pp. 333-370. J. t. 



