Chemistry and Physics. 467 



9. Fluorescence and Actinic Electricity. — In order to connect 

 together by a reasonable hypothesis the various phenomena of 

 luminescence, E. Wiedemann and G. C. Schmidt have sug- 

 gested that in many cases the absorbed light energy in the ions 

 of broken up molecules may determine when the molecules are 

 again formed — the phenomena of fluorescence and phosphores- 

 cence. G. C. Schmidt has taken up the subject again in order to 

 see whether the three phenomena ionisirung, fluorescenz and 

 actinoelectricitat are connected. He concludes from his researches 

 that 



(1) Ionizing and fluorescence do not stand in immediate con- 

 nection with light-electric sensitiveness. 



(2) In the case of elementary solid bodies and solid solutions 

 fluorescence and actino-electric phenomena are not related. 



(3) With the exception of uranium and thorium and their com- 

 binations, all bodies so far as they absorb ultra-violet light are 

 light-electric sensitive at high potentials. 



(4) Uranium and thorium and their combinations dissipate 

 positive electricity as well as negative. 



(5) The solid solutions of light-electric sensitive substances 

 are also light-electric sensitive. 



(6) Solid bodies which are light-electric sensitive preserve this 

 property in their solid solutions. 



(7) The solid solutions which hold uranium salts are not light- 

 electric sensitive. They dissipate, however, equally well positive 

 and negative electricity in the dark. 



(8) In those bodies, which after being submitted to cathode 

 rays become intensely thermo-luminescent when heated, nega- 

 tive electricity is strongly dissipated. — Wied. Ann., No. 4, pp. 

 708-724, 1898. J. t. 



10. New Method of determining the inclination and horizontal 

 intensity of the earth's magnetism. — Various attempts have been 

 made to perfect the method of obtaining these quantities by means 

 of the earth inductor, but the method has not been considered a 

 precise one. G. Meyer describes an earth inductor which is kept 

 in continuous rotation, and the neutral condition in which there is 

 no current is determined by means of a telephone or capillary 

 electrometer. The inclination can be measured to one-tenth of a 

 degree. The instrument is especially fit for transportation, since 

 no galvanometer is used. — Wied. Ann., No. 4, pp. 742-751, 1898. 



J. T. 



11. Rontgen Mays and ordinary light. — Sir G. Stokes and 

 Professor J. J. Thomson have lately developed the theory that 

 these rays are evidence of electromagnetic impulses. Lord Ray- 

 leigh criticises this contention and is surprised by the theory 

 " that the Rontgen rays are not waves of very short wave length 

 but impulses," and asks if short waves are inadmissible why are 

 not longer waves also, and what becomes of Fourier's theorem 

 according to which any disturbance ean be analyzed into regular 

 waves. Lord Rayleigh refers to a paper in which he proved that 



