Chemistry and Physics. 75 



satisfactory in practice. The dichromate burned like tinder, the 

 nitrogen coming off with such rapidity as to carry away some of 

 the oxide and perhaps even some of the dichromate. Moreover, 

 the gas set free does not seem to be pure nitrogen, but has a 

 brownish color with a nitrous smell and an acid reaction. The 

 second method resulted satisfactorily and gave for the ratio of 

 the atomic mass of chromium to that of hydrogen in six experi- 

 ments 52-130, 52-010, 52-020, 52'129, 52-016, 52-059 : the general 

 mean being 52-061.— J. Ghem. Soc, lv, 213, April, 1889. 



G. F. B. 



3. On the new Element Gnomium. — Hugo Muller exhibited at 

 the Conversazione of the Royal Society on May 8th, some com- 

 pounds of the new element gnomium discovered by Krilss and 

 Schmidt of Munich, as associated with the metals nickel and 

 cobalt. Among the preparations shown were gnomium oxide, 

 gnomium chloride (in aqueous solution), nickel from which the 

 gnomium, which had always accompanied it hitherto, had been 

 removed ; and nickel oxide also free from gnomium. — Nature, xl, 

 67, May, 1889. G. f. b. 



4. Concentration of Electric Radiation by lenses. — "Prof. O. J. 

 Lodge and James L. Howard have constructed two large cylin- 

 drical lenses of piano-hyperbolic section of mineral pitch cast in 

 zinc moulds, the plane faces being nearly a meter square, the 

 thickness at vertex 21 centimeters, and each lens weighed about 

 3 cwt. The eccentricity of the hyperbola was made 1*7 to ap- 

 proximate to the index of refraction of the substance. The 

 lenses were mounted about six feet apart with their plane faces 

 parallel and toward each other on a table and an oscillator was 

 placed about the principal focal line of one of them at a distance 

 of 51 centimeters from the vertex. The field was explored by a 

 linear receiver made out of two pieces of copper wire mounted in 

 line on a piece of wood, and the air gap between their inner ends 

 was adjustable by a screw. When the oscillator worked satis- 

 factorily, the receiver would respond to about 120 centimeters, 

 and with the lenses the distance was 450. The receiver re- 

 sponded anywhere between the lenses and within the wedge 

 between the second lense and its focal line, the boundaries being 

 clearly defined, but no special concentration was noticed about 

 the focus. Interference experiments were carried out by placing 

 a sheet of metal against the flat face of the second lens, and de- 

 termining the position of minimum intensity between the lenses. 

 The distance between these points was 50'5 centimeters, corres- 

 ponding with a wave-length of 101 centimeters, whereas the 

 calculated wave-length of the oscillator was 100 centimeters. In 

 a discussion upon the results of this experiment Prof. Fitzgerald 

 said that he had made experiments on electrical radiations analo- 

 gous to Newton's rings, and had successfully observed the central 

 dark spot and the first dark band." — Physical Soc, London, May 

 11, 1889. j. t. 



5. Wave-length of the principal line in the Sp>ectrum of the 

 Aurora. — Huggins details a careful determination of the position 



