698 



Professor Dewar 



[June 10, 



power. Cotton wool, moistened with liquid oxygen, was strongly 

 attracted by the magnet, and the liquid oxygen was actually sucked 

 out of it on to the poles. A crystal of ferrous sulphate, similarly 

 cooled, stuck to one of the poles. 



The lecturer remarked that fluorine is so much like oxygen in its 

 properties, that he ventured to predict that it will turn out to be a 

 magnetic gas. 



"^t^K'il^EE^ "^^ 



Magnetic Attraction of Liquid Oxygen. 



Nitrogen liquefies at a lower temperature than oxygen, and one 

 would expect the oxygen to come down before the nitrogen when air 

 is liquefied, as stated in some text -books, but unfortunately it is not 

 true. They liquefy together. In evaporating, however, the nitrogen 

 boils off before the oxygen. He poured two or three ounces of 

 liquid air into a large test-tube, and a smouldering splinter of wood 

 dipped into the mouth of the tube was not re-ignited ; the bulk of 

 the nitrogen was nearly five minutes in boiling off, after which a 

 smouldering splinter dipped into the mouth of the test-tube burst 

 into flame. 



Between the poles of the magnet all the liquefied air went to 

 the poles; there was no separation of the oxygen and nitrogen. 

 Liquid air has the same high insulating power as liquid oxygen. 

 The phenomena presented by liquefied gases present an unlimited 

 field for investigation. At — 200° C. the molecules of oxygen had 

 only one-half of their ordinary velocity and had lost three-fourths 

 of their energy. At such low temperatures they seemed to be 

 drawing near what might be called " the death of matter," so far 

 as chemical action was concerned ; liquid oxygen, for instance, had 

 no action upon a piece of phosphorus and potassium or sodium 

 dropped into it ; and once he thought and publicly stated, that 

 at such temperatures all chemical action ceased. That statement 



