1895.] on Argon. 537 



prepare " nitrogen " from it by removal of oxygen and moisture, we 

 obtain a gas heavier than atmospheric nitrogen, a result which proves 

 that the ordinary nitrogen of the atmosphere is not a simple body, 

 but is capable of being divided into parts by so simple an agent as 

 the tobacco pipe. 



If it be admitted that the gas is in the atmosphere, the further 

 question arist s as to its nature. 



At this point I would wish to say a word of explanation. 

 Neither in our original announcement at Oxford, nor at any time 

 since, until the 31st of January, did we utter a word suggesting that 

 argon was an element ; and it was only after the experiments upon 

 the specific heats that we thought W6 had sufficient to go upon in 

 order to make any such suggestion in public. I will not insist that 

 that observation is absolutely conclusive. It is certainly strong 

 evidence. But the subject is difficult, and one that has given rise to 

 some difference of opinion among physicists. At any rate this 

 property distinguishes argon very sharply from all the ordinary 

 gases. 



One question which occurred to us at the earliest stage of the 

 enquiry, as soon as we knew that the density was not very different 

 from 21, was the question of whether, possibly, argon could be a 

 more condensed form of nitrogen, denoted chemically by the symbol 

 N 3 . There seem to be several difficulties in the way of this suppo- 

 sition. Would such a constitution be consistent with the ratio of 

 specific heats (1 * 65) ? That seems extremely doubtful. Another 

 question is, can the density be really as high as 21, the number 

 required on the supposition of N 3 ? As to this matter, Professor 

 Ramsay has repeated his measurements of density, and he finds that 

 he cannot get even so high as 20. To suppose that the density of 

 argon is really 21, and that it appears to be 20 in consequence of 

 nitrogen still mixed with it, would be to suppose a contamination with 

 nitrogen out of all proportion to what is probable. It wouid mean 

 some 14 per cent, of nitrogen, whereas it seems that from one-and- 

 a-half to two per cent, is easily enough detected by the spectroscope. 

 Another question that may be asked is, would N 3 require so much 

 cooling to condense it as argon requires ? 



There is one other matter on which I would like to say a word 

 — the question as to what N 3 would be like if we had it. There 

 seems to be a great discrepancy of opinions. Some high authorities, 

 among whom must be included, I see, the celebrated Mendeleef, 

 consider that N 3 would be an exceptionally stable body ; but most 

 of the chemists with whom I have consulted are of opinion that N 3 

 would be explosive, or, at any rate, absolutely unstable. That is a 

 question which may be left for the future to decide. We must 

 not attempt to put these matters too positively. The balance of 

 evidence still seems to be against the supposition that argon is N 3 , 

 but for my part I do not wish to dogmatise. 



A few weeks ago we had an eloquent lecture from Professor 



