MAGNETIC PROPETiTIES OF LIQUID OXYGEN.* 



By Prof. James Dewar, F. K. S. 



After alludinii' to the generous aid vvliieh lie had received both from 

 the Eoyal Institution and from others in connection with his researches 

 on tlie properties of liquid oxygen, and to the untiring assistance ren- 

 dered him by his co-workers in the laboratory, Prof. Dewar said that on 

 the occasion of tlie commemoration of the centenary of tlie birth of 

 Michael Faraday he had demonstrated some of the properties of liqnid 

 oxygen. He hoped that evening to go several steps further, and to show 

 liquid air, and to render visible some of its more extraordinary prop- 

 erties. 



The apparatus employed consisted of the gas-engine down stairs, 

 which was driving two compressors. The chamber containing the oxy- 

 gen to be li(iuefied was surrounded by two circuits, one traversed by 

 etiiylene, the other by nitrous oxide. Some liquid ethylene was admitted 

 to the chamber belonging to its circuit, and there evaporated. It was 

 then returned to the compressor as gas and liquefied, and thence again 

 into tlie compressor as required. A similar cycle of operations was 

 carried out with the nitrous oxide. There Avas a hundredweight of 

 licjuid ethylene prepared for the experiment. Ethylene was obtained 

 from alcohol by the action of strong sulphuric acid. Its manufacture 

 was exceedingly difficult, because dangerous, and as the efficiency of 

 the process only amounted to 15 or 20 i)er cent the ]ireparation of a 

 hundredweight of liquid was no light task. The cycle of operations, 

 which, for want of time, was not fully explained, was the same as that 

 commonly employed in refrigerating machinery working with ether or 

 ammonia. 



The lecturer then exhibited to the audience a pint of liquid oxygen, 

 which by its cloudy appearance showed that it contained traces of 

 impurity. The oxygen was filtered, and then ai)peared as a clear trans- 

 parent liquid with a slightly blue tinge. The density of oxygen gas at 

 —182° C. is normal, and the latent heat of volatilization of the liquid is 

 about 80 units. The capillarity of liquid oxygen at its boiling-point was 



* Abstract of discourse delivered at the Eoyal Institution, Friday evening, June 

 10, 1892. (From Proceedings of the EoyaJ JnstUuUon of Great Britain, vol. xiii, pp. 

 695-699.) 



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