1892.] 



on Magnetic Properties of Liquid Oxygen. 



697 



altitudes. The lines at all elevations come out more strongly when 

 the sun is low, because tlie rays then have to traverse greater thick- 

 nesses of the earth s atmosphere. 



Michael Faraday's experiments made in 1849 on the action of 

 magnetism on gases opened up a new field of investigation. The 

 following table, in which + means " magnetic " and — means " nega- 

 tive," summarises the results of Faraday's experiments. 



Becquerel was before Faraday in experimenting upon this subject. 

 Becquerel allowed charcoal to absorb gases, and then examined the 

 properties of such charcoal in the magnetic field. He thus discovered 

 the magnetic properties of oxygen to be strong, even in relation to a 

 solution of ferrous chloride, as set forth in the following table : — 



Specific Magnetism, Equal Weights (Becquerel). 



Iron + 1,000,000 



Oxygen + 377 



Ferrous chloride solution, sp. gr. 1-4331 .. + 140 



Air + 88 



Water - 3 



The lecturer took a cup made of rock salt, and put in it some 

 liquid oxygen. The liquid did not wet rock salt, but remained 

 in a spheroidal state. The cup and its contents were placed be- 

 tween and a little below the poles of an electro-magnet. When- 

 ever the circuit was completed, the liquid oxygen rose from the cup 

 and connected the two poles, as represented in the cut, which is 

 copied from a photograph of the phenomenon. Then it boiled away, 

 sometimes more on one pole than the other, and when the circuit was 

 broken it fell off the pole in drops back into the cup. He also 

 showed that the magnet would draw up liquid oxygen out of a tube. 

 A test-tube containing liquid oxygen when placed in the Hughes 

 balance produced no disturbing effect. The magnetic moment of 

 liquid oxygen is about 1000 when the magnetic moment of iron is 

 taken as 1,000,000. On cooling some bodies increased in magnetic 



Vol. XIII. (No. 86.) 3 a 



