SOME PHYSICAL PROBLEMS 



subject ; for here are four or five other elementary sub- 

 stances which, if far less abundant than oxygen and 

 nitrogen, are no less widely distributed and universally 

 present in the atmosphere, yet no one of which ap- 

 parently takes any chemical share whatever in min- 

 istering to the needs of the living organism. This 

 surely is an enigma. 



Taking another point of view, let us try to imagine 

 the real status of these new gases of the air. We 

 think of argon as connected with nitrogen because in 

 isolation experiments it remains after the oxygen has 

 been exhausted, but in point of fact there is no such 

 connection between argon and nitrogen in nature. 

 The argon atom is just as closely in contact with the 

 oxygen in the atmosphere as with the nitrogen; it 

 simply repels each indiscriminately. But consider a 

 little further; the argon atom not only repels all ad- 

 vance on the part of oxygen and nitrogen, but it 

 equally holds itself aloof from its own particular kin- 

 dred atoms. The oxygen or nitrogen atom never rests 

 until it has sought out a fellow, but the argon atom 

 declines all fellowship. When the chemist has played 

 his tricks upon it, it finds itself crowded together with 

 other atoms of the same kind ; but lift up the little test- 

 tube and these scurry off from one another in every 

 direction, each losing its fellows forever as quickly as 

 possible. 



As one ponders this one is almost disposed to sug- 

 gest that the atom of argon (or of krypton, helium, 

 neon, or zenon, for the same thing applies to each and 

 all of these) seems the most perfect thing known to us 

 in the world, for it needs no companionship, it is self- 



