246 Mr. H. P. Warah: Apparatus for the Preparation of 



not allowed to fall back, until the ionized molecule reaches 

 the electrode. It might be expected, therefore, that the glow 

 would only appear, if at all, on the surface of the grid, 

 whereas actually it appears distributed throughout the whole 

 vessel. 



Several explanations can be suggested, none of them very 

 satisfactory : — (1) It may be that the spectrum is emitted 

 when the CO ion and molecule react to form C0 2 : for when 

 that happens there may be a rearrangement of electrons 

 accompanied by decrease of electrostatic energy. But that 

 explanation is difficult to apply to nitrogen and many other 

 gases, which show a many-lined spectrum when there can 

 hardly be much recombination. (2) The spectrum may 

 represent the return or an electron which has been displaced 

 inside the atom so that ionization has not occurred. If that 

 explanation were correct the spectrum should not be com- 

 plete ; but there is the grave objection that all relevant 

 experiments show that the many-lined spectrum is not deve- 

 loped at all until atoms receive the energy necessary for 

 ionization. (3) The ions may be neutralized at the electrode, 

 but then travel through the gas emitting their spectrum ; but 

 it is unlikely that the emission lasts long enough for the 

 luminosity to be distributed in this way. The problem is 

 recommended to the attention of spectroscopists. 



XXVIII. On a Convenient Apparatus for the Preparation of 

 Small Quantities of Pure Nitrogen or Carbon Monoxide. By 

 H. P. War AN, M.A., Government Scholar of the University 

 of Madras *. 



rj^HOUGrH nitrogen is by far the commonest of gases, yet 

 A to obtain it in a pure state for spectroscopic or other 

 purposes is a matter of some difficulty. To prepare it directly 

 from the atmosphere would mean the absorption of the rest 

 of the gases, and the removal of traces of the rare gases offers 

 great experimental difficulties, and it is not worth the labour 

 and complications involved when only small quantities of 

 gases are required. Attempting to prepare it by heating 

 some easily decomposable nitrogen compound would inva- 

 riably bring about traces of the various oxides of nitrogen 

 whose elimination again is a matter of some difficulty. 

 Further, some of these reactions are rather violent and un- 

 controllable, and hence unsuitable when small quantities of 

 pure gases are particularly required. 



* Communicated by Sir Ernest Rutherford, F.R.S. 



