712 



SCIENCE. 



[N. S. Vol. I. No. 26. 



announcement at Oxford, nor at anj^ time 

 since, until tlie 31st of January, did we 

 utter a word suggesting that argon was 

 an element; and it was onlj^ after the ex- 

 periments upon the specific heats that we 

 thought that we had suificient to go upon 

 in order to make any such suggestion in 

 public. I will not insist that that observa- 

 tion is absolutely conclusive. It is cer- 

 tainly 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 verj^ differ- 

 ent from 21, was the question of whether, 

 possibly, argon could be a more condensed 

 form of nitrogen, denoted chemically by the 

 symbol N3 . There seem to be several diffi- 

 culties in the way of this supposition. 

 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 sup- 

 position of Ng? As to this matter. Professor 

 Eamsay 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 would 

 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 maj- be 

 asked is. Would ISTg require so much cool- 

 ing 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, would be like if we had it. 



There seems to be a great discrepancj' of 

 .opinions. Some high authorities, among 

 whom must be included, I see, the cele- 

 brated Mendeleef, consider that Ng would 

 be an exceptional^ stable body; but most 

 of the chemists with whom I have consulted 

 are of opinion that IsTs 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 N3, but for 

 mjr part I do not wish to dogmatise. 



A few weeks ago we had an eloquent 

 lecture from Professor Riicker on the life 

 and work of the illustrious Helmholtz. It 

 will be known to many that during the last 

 few months of his life Helmholtz lay pros- 

 trate in a semi-paralyzed condition, forget- 

 ful of many things, but still retaining a 

 keen interest in science. Some little while 

 after his death we had a letter from his 

 widow, in which she described how inter- 

 ested he had been in our prelimiuarj^ an- 

 nouncement at Oxford upon this subject, 

 and how he desired the account of it to be 

 read to him over agaia. He added the 

 remark: "I always thought that there 

 must be something more iu the atmosphere.'' 



LLOYD MOBGAK UPON IKSTINCT. 

 In the last number of Natural Science 

 Professor C. Lloyd Morgan gives a valuable 

 synopsis of the various definitions of in- 

 stinct which have been proposed by Dar- 

 win, Wallace, Romanes, James, Spencer 

 and other writers upon this subject. He 

 shows that surprisingly wide differences of 

 opinion prevail and concludes that, " Since 

 the question of origin is still sub judice, the 

 definition should be purely descriptive, so 

 as not to prejudge this question. And 

 since the phenomena of instinct can only 

 be rightly understood in their relation to 

 automatism connate and acquired, to im- 



