SOME PHYSICAL PROBLEMS 



globe has been imbibing pretty constantly ever since 

 lungs came into fashion. But in another view the 

 universal presence of these gases in the air makes it 

 seem all the more wonderful that they could so long 

 have evaded detection, considering that chemistry has 

 been a precise science for more than a century. Dur- 

 ing that time thousands of chemists have made millions 

 of experiments in the very midst of these atmospheric 

 gases, yet not one of the experimenters, until recently, 

 suspected their existence. This proves that these 

 gases are no ordinary substances common though 

 they be. Personally I have examined many scientific 

 exhibits in many lands, but nowhere have I seen any- 

 thing that filled my imagination with so many scien- 

 tific visions as these little harmless test-tubes at the 

 back of Professor Ramsay's desk. Perhaps I shall at- 

 tempt to visualize some of these imaginings before 

 finishing this paper, but for the moment I wish to 

 speak of the modus operandi of the discovery of these 

 additions to the list of elements. 



The discovery of argon came about in a rather singu- 

 lar way. Lord Rayleigh, of the Royal Institution, had 

 noticed in experiments with nitrogen that when sam- 

 ples of this element were obtained from chemicals, such 

 samples were uniformly about one per cent, lighter in 

 weight than similar quantities of nitrogen obtained 

 from the atmosphere. This discrepancy led him to 

 believe that the atmospheric nitrogen must contain 

 some impurity. 



Curiously enough, the experiments of Cavendish, 

 the discoverer of nitrogen experiments made more 

 than a century ago had seemed to show quite con- 



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