Chemistry and Physics. 151 



with a solution of iodine in carbon disulphide, is made evident by 

 the incandescence of a platinum plate. Lommel suggests the use 

 of phosphorescent substances to render this focus visible. Bal- 

 main's luminous paint answers the purpose ; but the author prefers 

 a greenish-blue phosphorescent calcium sulphide. When this has 

 been made slightly phosphorescent by ordinary daylight, it is in- 

 creased to a bright luminosity by the less refrangible, especially 

 the ultra-red, rays. When the radiation is moderately strong, 

 this luminosity lasts for hours and is visible for some time even 

 after the radiation ceases. Then a dark spot takes the place of the 

 bright one, the luminous power having been diminished or en- 

 tirely destroyed in consequence of the increased emission. If the 

 powder be placed between two plates of glass, the ultra-red por- 

 tion of the spectrum produces a greenish-blue phosphorescence 

 visible on both sides of the glass. If the dark focus be received 

 on this screen, it appears as a bright spot on a feebly luminous 

 ground, which changes into a black spot after some time, looking as 

 if a hole had been made through the luminous surface. The 

 author suggests the use of a solution of nigrosin in chloroform or 

 alcohol in place of the iodine in carbon disulphide employed by 

 Tyndall, for filtering out the luminous rays. The nigrosin trans- 

 mits only ultra-red rays. Since these rays are considerably ab- 

 sorbed by alcohol the solution in this menstruum answers well 

 for the above described experiment, since the phosphorescent 

 luminosity lasts longer. The solution in chloroform is much more 

 diathermanous and answers well for showing the thermal effects at 

 the focus. So sensitive are these phosphorescent substances to 

 the ultra-red rays, that the flame of gas, of a lamp or even of a 

 candle may be made to show the phenomenon. Using a lens aiid 

 a cell filled with the black liquid, a sharp bright image appears on 

 the screen, which gradually diminishes and finally changes into a 

 dark image on a brighter ground. — Wied. Ann., II, xxvi, 157, 

 1885 ; Phil. Mag., V, xx,547, Dec. 1885. g. f. b. 



4. Improved method of preparing Nitrogen dioxide. — Kaem- 

 iiEREE has suggested an improved method of preparing nitrogen 

 dioxide by which a much steadier flow of this gas is secured. 

 The apparatus consists of a two-necked Woulfe's bottle, having 

 a dropping funnel in one of the openings and an evolution 

 tube suitable for washing or drying the gas in the other. The 

 bottle is one- third filled with a saturated solution of sodium 

 nitrate, and strips of copper are introduced. To evolve the gas, 

 concentrated sulphuric acid is allowed to flow into the bottle 

 more or less rapidly accoi'ding to the quantity of gas desired. 

 With a bottle of two liters capacity and a funnel-tube of 500 c. c, 

 the yield of nitrogen dioxide gas may be maintained steady at 

 the rate of a liter in five minutes. — Per. Perl. Chem. Ges., xviii, 

 3064, Dec. 1885. G. F. B. 



5. On the Action of Carbon monoxide and the vapor of 

 Water at high Temperatures. — Naumanst and Pistor have con- 

 tinued their researches on the phenomena attending the produc- 



