332 Intelligence and Miscellaneous Articles. 



and volatilize them again a dozen times in contact with the same 

 mass of gas, without the appearance of the spark which exploded 

 between the electrodes being modified in the slightest degree. I 

 made use of the Holtz machine, or an induction-coil with the addi- 

 tion of a Leyden jar : the space between the poles was rosy violet, 

 and gave the grooved spectrum with the utmost purity. When 

 the disruptive spark of the Holtz machine is employed, the jet of 

 rosy- violet flame, which gives the grooved spectrum, is instan- 

 taneous ; we can assure ourselves of this by a very simple method : 

 the luminous jet is viewed through the glass wheel of the machine, 

 on which little black points are traced with ink. Now these points 

 appeared perfectly distinct, even when the handle made sixty turns 

 in a minute ; we can hence infer that the discharge does not last a 

 thirty- thousandth of a second. 



2. By volatilization the sodium can be readily brought into the 

 vicinity of the electrodes. Jt presents itself then, as always, under 

 the aspect of very pure silvery white shining globules ; but if th( 

 tube be brought into play, the portions submitted to the action of 

 the jet of flame tarnish immediately : the metallic appearance 

 completely disappears ; and the surface of the sodium becomes 

 brownish black. At the same time are seen the changes in the 

 appearance of the electric jet induced by greater rarefaction. If 

 we renew the surface of the sodium, the action continues and the 

 nitrogen-spectrum entirely disappears ; the light is yellowish, and 

 due for the most part to the sodium. I say, for the most part ; for, 

 in these conditions of an almost absolute vacuum some traces of 

 foreign lines are always perceived in the spectrum, attributable to 

 impurities of the electrodes and of the inner surface of the glass. 

 In this case the tube, being cold, does not permit the spark of the 

 Leyden jar to pass. 



I have made a direct experiment to manifest this absorption of 

 nitrogen by sodium under the influence of electricity. I had 

 tube constructed like the preceding, but carrying a truncated 

 barometer ; and I introduced into it nitrogen at the pressure of 

 27 millims. The absorption of the gas was sufficiently sensible for 

 the eye to be able to follow the rise of the column of mercury. 

 After some minutes, the sodium-surface having been renewed 

 twice, no difference could be perceived between the levels of the 

 mercury in the two branches of the manometer. 



I have moreover endeavoured to trace the chemical characters 

 of this absorption : I broke a tube and separately treated with 

 water a portion of the sodium which remained bright and a portion 

 altered by electricity. Into both solutions I poured some of 

 Nessler's reagent (iodargyrate of potassium with an excess of soda). 

 One of the liquors became very yellow ; it was that into which the 

 altered sodium had been thrown. The other did not change its 

 appearance ; there had therefore been formed under the influence 

 of the electricity some nitride of sodium, decompoeable by water 

 with production of ammonia. This body is only generated at a 

 higher temperature than a red-heat, like the nitride of magnesium, 

 or is even not directly produced at any degree of heat, like am- 



