536 Lord Bayleigh [April 5, 



Several questions may be asked, upon which I should like to say 

 a word or two, if you will allow me to detain you a little longer. 

 The first question (I do not know whether I need ask it) is, have we 

 got hold of a new gas at all? I had thought that that might be 

 passed over, but only this morning I read in a technical journal the 

 suggestion that argon was our old friend nitrous oxide. Nitrous 

 oxide has, roughly, the density of argon ; but that, as far as I can see, 

 is the only point of resemblance between them. 



Well, supposing that there is a new gas, which T will not stop to 

 discuss, because I think the spectrum alone would be enough to prove 

 it, the next question that may be asked is, is it in the atmosphere ? 

 This matter naturally engaged our earnest attention at an early 

 stage of the enquiry. I will only indicate in a few words the argu- 

 ments which seem to us to show that the answer must be in the 

 affirmative. 



In the first place, if argon be not in the atmosphere, the original 

 discrepancy of densities which formed the starting point of the 

 investigation remains unexplained, and the discovery of the new gas 

 has been made upon a false clue. Passing over that, we have the 

 evidence from the blank experiments, in which nitrogen originally 

 derived from chemical sources is treated either with oxygen or with 

 magnesium, exactly as atmospheric nitrogen is treated. If we use 

 atniosjiheric nitrogen, we get a certain proportion of argon, about 

 1 per cent. If we treat chemical nitrogen in the same way we get, 

 I will not say absolutely nothing, but a mere fraction of what we 

 should get had atmospheric nitrogen been the subject. You may 

 ask, why do we get any fraction at all from chemical nitrogen? It 

 is not difficult to explain the small residue, because in the manipula- 

 tion of the gases large quantities of water are used ; and, as I have 

 already explained, water dissolves argon somewhat freely. In the 

 processes of manipulation some of the argon will come out of 

 solution, and it remains after all the nitrogen has been consumed. 



Another wholly distinct argument is founded upon the method of 

 diffusion introduced by Graham. Graham showed that if you pass 

 gas along porous tubes you alter the composition, if the gas is a 

 mixture. The lighter constituents go more readily through the 

 pores than do the heavier ones. The experiment takes this form. 

 A number of tobacco pipes — eight in the actual arrangement — are 

 joined together in series with indiarubber junctions, and they are 

 put in a space in which a vacuum can be made, so that the space 

 outside the porous pipes is vacuous or approximately so. Through 

 the pipes ordinary air is led. One end may be regarded as open to 

 the atmosphere. The other end is connected with an aspirator so 

 arranged that the gas collected is only some 2 per cent, of that which 

 leaks through the porosities. The case is like that of an Australian 

 river drying up almost to nothing in the course of its flow. Well, if 

 we treat air in that way, collecting only the small residue which is 

 less willing than the remainder to penetrate the porous walls, and then 



