532 Lord Bayleigh [April 5, 



method — is the easier and the more to be recommended ; but I confess 

 that I am quite at a loss to do so. One difficulty in the comparison 

 arises from the fact that they have been in different hands. As far 

 as I can estimate, the quantities of nitrogen eaten up in a given time 

 are not very different. In that respect, perhaps, the magnesium 

 method has some advantage ; but, on the other hand, it may be said 

 that the magnesium process requires a much closer supervision, so 

 that, perhaps, fourteen hours of the oxygen method may not unfairly 

 compare with eight hours or so of the magnesium method. In 

 practice a great deal would depend upon whether in any particular 

 laboratory alternate currents are available from a public supply. If 

 the alternate currents are at hand, I think it may probably be the 

 case that the oxygen method is the easier ; but, otherwise, the 

 magnesium method would, probably, be preferred, especially by 

 chemists who are familiar with operations conducted in red-hot tubes. 

 I have here another experiment illustrative of the reaction 

 between magnesium and nitrogen. Two rods of that metal are 

 suitably mounted in an atmosphere of nitrogen, so arranged that 

 we can bring them into contact and cause an electric arc to form 

 between them. Under the action of the heat of the electric arc the 

 nitrogen will combine with the magnesium ; and if we had time to 

 carry out the experiment we could demonstrate a rapid absorption of 

 nitrogen by this method. When the experiment was first tried, I had 

 hoped that it might be possible, by the aid of electricity, to start the 

 action so effectively that the magnesium would continue to burn 

 independently under its own developed heat in the atmosphere of 

 nitrogen. Possibly, on a larger scale, something of this sort might 

 succeed, but I bring it forward here only as an illustration. We 

 turn on the electric current, and bring the magnesiums together. 

 You see a brilliant green light, indicating the vaporisation of the 

 magnesium. Under the influence of the heat the magnesium burns, 

 and there is collected in the glass vessel a certain amount of 

 brownish-looking powder which consists mainly of the nitride of 

 magnesium. Of course, if there is any oxygen present it has the 

 preference, and the ordinary white oxide of magnesium is formed. 



The gas thus isolated is proved to be inert by the very fact of its 

 isolation. It refuses to combine under circumstances in which 

 nitrogen, itself always considered very inert, does combine — both in 

 the case of the oxygen treatment and in the case of the magnesium 

 treatment ; and these facts are, perhaps, almost enough to justify the 

 name which we have suggested for it. But, in addition to this, it has 

 been proved to be inert uncier a considerable variety of other conditions 

 such as might have been expected to tempt it into combination. I 

 will not recapitulate all the experiments which have been tried, 

 almost entirely by Professor Ramsay, to induce the gas to combine. 

 Hitherto, in our hands, it has not done so ; and I may mention that 

 recently, since the publication of the abstract of our paper read 





