318 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE, 



I. Chemistry and Physics. 



1. A Chemically Active Form of Nitrogen Produced by the 

 Electric Discharge. — R. J. Strutt has observed a very remarka- 

 ble effect upon pure nitrogen when it is subjected to the action of 

 an electric discharge from a Leyden jar in an exhausted tube. It 

 is thus caused to glow for some time after the discharge has been 

 discontinued. This glowing nitrogen has a characteristic band 

 spectrum with green, yellow and red bands. It was found that 

 the change which gives rise to the after-glow is retarded by heat- 

 ing and accelerated by cooling. When the gas was passed 

 through an electric field with the object of removing gaseous 

 ions, the glow was unaffected. When the glowing gas was 

 passed over a small pellet of ordinary phosphorus, a violent reac- 

 tion occurred, accompanied by the absorption of some of the gas 

 and the formation of red phosphorus. This reaction was used to 

 determine the percentage of active nitrogen in the gas. In one 

 experiment the phosphorus increased in weight by 15*5 mg after 

 the jjassage of 2540 Ci: , corresponding to the absorption of 12 - 2 CC 

 or 1 /210th part of the gas. On contact with iodine the yellow 

 glow is replaced by a magnificent bright blue flame giving a 

 brilliant banded spectrum. Sulphur and arsenic when heated 

 give faint blue and green flames respectively ; selenium, anti- 

 mony and carbon are without action. Hydrogen merely acts as a 

 diluent, but oxygen destroys the glow without any new luminous 

 effect. Compound substances when volatilized in the gas give 

 rise to the corresponding band spectra, and in this way spectra of 

 compounds which are unstable at the temperature of the Bunsen 

 flame may be readily obtained. The modified nitrogen reacts 

 with organic halogen compounds, setting free the halogen, and 

 combining with carbon to form cyanogen, of which a brilliant 

 spectrum is obtained during the reaction. Cyanogen is formed 

 also when the gas acts upon acetylene. With nitric oxide it 

 yields nitrogen peroxide and a green flame is produced giving a 

 continuous spectrum. It is suggested that this reaction may be 

 represented as 



2NO + N = N0 2 + N 2 . 



Water and carbon dioxide have no action upon the glowing 

 nitrogen. Ammonia, cupric oxide, and manganese dioxide destroy 

 the glow. — Jour. Chem. Soc, c. II, 483. h. l. w. 



2. Gravimetric Determination of Fluorine. — G. Starck has 

 devised a new method for making this determination. The solu- 

 tion containing the fluorine is neutralized and a large excess of 

 cold saturated solution of lead chloride is added, which precipi- 



