Chemistry and Physics. 475 



hypothesis Professor J. J. Thomson explains why metals which 

 charge positively the strongest, also have the greatest sympathy 

 for positive electricity and destroy negative charges to the greatest 

 extent. It has been known that many spots on cubes of fluorspar 

 become negatively charged by light. These, according to the 

 above hypothesis, must possess a greater attraction for negative 

 electricity than for positive, and it would be expected that under 

 the influence of light a positive charge on them would be dissi- 

 pated. G. C. Schmidt has undertaken a research to settle this 

 point and he concludes that fluorspar always charges itself posi- 

 tively at the corners of the crystal and especially on fresh cleavages, 

 and always negatively in the middle. At these places, which 

 are strongest electrified positively in light, the negative electricity 

 is the most quickly dissipated. The positions on fluorspar which 

 are negatively electrified by light are also deprived of negative 

 electricity. Selenium behaves in a similar manner, and the 

 phenomena that bodies charge themselves under the influence of 

 light and dissipate negative electricity are separate phenomena, 

 which are not so closely related as has been supposed. The 

 theory supported by Prof. J. J. Thomson, on the working of light 

 on non-electrified and on negatively charged bodies, is not con- 

 firmed by this investigation. — Wied. Ann., No. 11, 407-414. 



J. T. 



8. On a magnetic method of showing metallic iron. — William 

 Duane has shown that the damping effect of a steady magnetic 

 field on oscillating bodies is more delicate than any chemical 

 analysis for the detection of traces of iron. He has extended his 

 investigation to the effect of rotating magnetic fields and finds 

 that in this case the method is even more sensitive that that 

 formerly employed with the steady field. — Wied. Ann.,^0. 11, 

 1897, p. 543. J. t. 



9. On the spectra of certain stars. — A series of observations 

 have been carried on at Potsdam by Vogel and Wilsing having 

 as their object the classification according to their spectra of stars 

 falling in the first spectral class. In the case ot one hundred 

 stars the presence of cleveite gas in their atmosphere could be 

 established (Class lb) ; they formed a fourth part of all the stars 

 of Class I which were observed. — Sitzungsberichte d. K. Preuss. 

 Akad. der Wiss., Berlin, Oct. 21. 



10. On the structure of the Cathode Light and the nature of the 

 Lenard Pays — Goldstein shows that the so-called third layer 

 of the cathode light consists of rays in straight lines' which have 

 their origin not on the surface of the cathode itself but from the 

 rays of the second layer. The author explains the Lenard rays 

 as due to diffusely reflected cathode rays. — Sitzberichte d. K. 

 Akad. Wiss., Berlin, Oct. 21. 



11.-4 new Nicol Prism. — It is announced that C. Leiss has de- 

 vised a new form of prism ot Iceland spar and glass which per- 

 mits of a saving of 50 per cent in the material. — Site. d. K. 

 Akad., Berlin, Oct. 21. 



