Chemistry and Physics. 67 



discovered that an arc lamp gives carbon bands as far as this 

 wave length in the ultra-violet which are of sufficient heating 

 effect. Some of the results of the previous photometric work are 

 corrected. 



The reflection power of silver falls off quickly below 450 fx^i. 

 and reaches a minimum of 4 per cent approximately at 320 /x/t. 

 While silver for visible rays is the best reflecting of all metals, it 

 is the poorest between 250-350 ya/x. Platinum, iron and nickel 

 show approximately the same reflecting power. The reflecting 

 power of speculum metal was investigated and is of especial 

 interest in view of concave gratings. Magnalium shows an 

 exceptionally high reflecting power. The reflecting power in the 

 extreme ultra-red possesses far more regularity than in the visible 

 and ultra-violet regions. — Ann. der Physik, 5, 1902, pp. 1-21. 



J. T. 



9. Spark Discharge from Metallic Poles in Water. — Dr. 

 WiLsiNG of Potsdam believes that the peculiarities of the spec- 

 trum of Novae can be explained by pressure, and accordingly has 

 studied spectra produced by the electric spark in water where it 

 is presumable that great pressure results. He arrived at the con- 

 clusion that displacement of lines and double lines occurred 

 which were in every way similar to those observed in the spec- 

 trum of Nova Aurigae. Sir Norman Lockyer has repeated Dr. 

 Wilsing's results and comes to the conclusion that shifts are 

 obtained under water which are in opposite directions to those 

 noticed in the dark lines of the spectra of Novae and that the 

 shift in the star does not arise from pressure. — Nature, May 22, 

 1902. 



10. Electrical Effect of Light. — P. Lenard contributes an 

 exhaustive paper on the effect of ultra-violet light in generating 

 cathode rays, and the bearing of this phenomena on radio-active 

 bodies. The velocity of the rays so excited is approximately 

 j-^ig-g- of the velocity of light. These rays show diffusiveness and 

 must be absorbed in great measure by gases. The method of 

 measure was by means of loss of charge. — Ann. der Physik., 5, 

 1902, pp. 149-198. J. T. 



11. Interference Tubes for Electrical Waves. — Various attempts 

 have been made to employ Quincke's resonating tubes for the 

 detection of electric Avaves. August Becker has made a num- 

 ber of measurements with such tubes and with a coherer. The 

 waves were propagated along the surface of the tubes and issued 

 into the air with scarcely diminished energy. Their length 

 within the tubes was 10*=™ and in free air V'S^"". The tubes were 

 filled with various liquids and the dielectric constants determined. 

 A list of such constants is appended. — A7i7i. der Physik, 5, 1902, 

 pp. 22-62. J. T. 



12. Laio of Velocity which Cathode Pays siffer by Peflection. 

 — If there is such a law, the reflected rays should be more power- 

 fully diverted by a magnet than the direct rays. E. Gehrcke 

 finds that this happens. As an exciter of the rays he employed 



