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Prof. H. E. Armstrong on Low-Temperature Research 



In this lecture, tlie opinion was expressed that liquid methane 

 would be the best cooling agent to use and Prof. D.-war pointed to 

 the fact that he had suggested and used this substance a year in 

 advance of MM. Cailletet and Wroblewski. 



" Liquid Air and the Zero of Abolute Temperature " was the 

 subject of the next discourse, on June 5, 1885. Xo abstract of this 

 lecture was published. 



The centenary of Faraday's birth was celebrated at the Royal 

 Institution in 1891, on Wednesday, June 17, when the Prince of 

 AVales opened the proceedings and Lord Rayleigh gave an address 

 on Faraday's Physical Work ; and again on Friday, June 26, when 

 Prof. Dewar lectured on the Chemical Work of Faraday in relation 

 to Modern Science. After brief references to the chemical work and 

 a condensed historical account of jhis researches on the liquefaction 

 of gases. Prof. Dewar gave further demonstrations of the properties 

 of Hquid oxygen, after liquefying it with the improved appliances 

 then in the Institution. It was on this occasion, I think, that the 

 startling demonstration was first given of the simple method of 

 clearing liquefied gases by mere filtration through an ordinary fluted 

 paper filter. The lowest temperature reached by Faraday was - 110°. 

 The lowest reached up to that time was - 210°. The boiUng-point 

 of hydrogen was calculated to be - 250°. 



It is interesting that, on this occasion. Sir Lyon Playfair, after 

 dwelling on the practical uses that were being made of liquefied gases, 

 referred to uses that might be made of them in words which were 

 a forecast of the awful purpose to which they have been put during 

 the present war. " Sulphurous acid," he said, " will, I am certain, 

 become most important in war, for if you took a brittle shell filled 

 with liquid sulphurous acid and threw it between the decks of a ship 

 it would produce such a stink that everybody would disappear in a 

 moment. The time is coming when other gases will be used in this 

 way." It came twenty-five years later, when the Germans introduced 

 the use in warfare of liquid chlorine and liquid phosgene, COCl.,, 

 irritant gases in comparison with which, though suffocating, sulphurous 

 acid is almost harmless. The idea seems to have been a favourite 

 one with Playfair, to judge from a passage in his Life, in which he 

 suggests the use of arsenic compounds for military purposes. 



Liquid air was first produced and its properties demonstrated at 

 a Friday evening lecture on " Magnetic Properties of Liquid Oxygen " 

 on June 10, 18U2. From that time onwards it ceased to be a scientific 

 curiosity and soon became the most familiar fluid at the Institution, 

 where it has constantly been used as a weapon of research. 



After showing that the nitrogen and oxygen in air liquefy 



