484 The Faraday Centenary. [June 26, 



Prof. Dewar then performed the experiment of actually producing 

 liquid oxygen, which was seen to boil quietly w^hen collected in an 

 open vessel at a temperature of — 180° C. The colour was slightly 

 blue, only a few particles of solid matter being visible, which Prof. 

 Dewar explained were traces of solid carbonic acid, the elimination of 

 which had given him considerable trouble. The lecturer further 

 proved by actual experiment on his own hand and on a glass vessel 

 that the liquid oxygen was in the spheroidal condition ; and also that 

 alcohol when added to the liquid became instantly solidified. The 

 usual test for oxygen by means of a glowing taper was also made 

 on the vapour given off by the liquid. The form and arrangement 

 of the apparatus employed on the lecture table is shown in Fig. 2. 



Prof. Dewar stated that the prosecution of the researches inaugu- 

 rated by Faraday was enabling scientists to approach nearer and 

 nearer to the zero of absolute temperature ; and the speculations 

 of physicists were now directed to the probable characteristics of 

 hydrogen and of matter in general when that condition should be 

 attained. At such a temperature the properties of matter would in 

 all probability be entirely changed ; the old Lucretian law would be 

 suspended, molecular motion would probably cease, and what might 

 be called the death of matter would ensue — as in fact the death of 

 chemical affinity and chemical action was known to take place at the 

 low temperatures already attainable. (Experiment proving this by 

 the immersion of phosphorus, sodium, and potassium in liquid oxygen.) 

 On the other hand, it was found that even at such low temperatures 

 oxygen retained its characteristic absorption spectrum.* Further 

 experiments were given proving the liquefaction of ozone by means 

 of liquid oxygen — a tube of the liquid thus produced showing the 

 characteristic deep blue colour of that substance. 



In conclusion, Prof. Dewar said that although great progress had 

 been made since Faraday's time, chemists were still working dis- 

 tinctly on the lines of his early researches ; and it seemed to him 

 that no fitter method of celebrating the centenary of Faraday's birth 

 could be chosen than the demonstration of the realisation of some of 

 his own ideas. 



* The recently discovered magnetic property of the liquid adds a new 



interest to this subatance. 



" Eoyal Institution, 10th December, 1891. 



"Dear Sir William Thomson, — The following observation, which I liave 

 just made, may interest the members of the Royal Society, and if you think it of 

 sufficient importance you may announce it at this day's meeting. 



" At 3 p.m. this afternoon I placed a quantity of liquid oxygen in the state 

 of rapid ebullition in air (and therefore at a temperature of — 18 1° C.) between the 

 poles of the historic Faraday magnet, in a cup-shaped pitce of rock salt (which I 

 have found is not moistened by liquid oxy^^eu, and therefore keeps it in the 

 spheroidal state), and to my surprise I have witnessed the liquid oxygen, as soon 

 as the magnet was stimulated, sud<lenly leap up io the poles and remain there 

 permanently attached until it evaporated. T«t see liquid oxygen t,uddenly attracted 

 by the magnet is a very beautiful contirmation of our knowledge of the properties 

 of gaseous oxygen.— Yours faithfully, James Dewar."— [Proc. Royal Society, 

 vol. 1. p. 24.] 



