LIQUID HYDROGEN. 141 



pressures, though the compression has not yet been carried so far as 

 to show an}^ repulsive force. In hj'drogen the repulsive force seems 

 to prevail even at ordinary pressures. This gas has never been lique- 

 fied, and it is probable that it never will be liquefied, as the attractive 

 force is so weak." 



In concluding his lectures on the nonmetallic elements, delivered at 

 the Royal Institution in 1852, and published the following year, Fara- 

 day said: ' 



"There is reason to believe we should derivv^ nuich information as 

 to the intimate nature of these nonmetallic elements, if we could suc- 

 ceed in obtaining h^^drogen and nitrogen in the liquid and solid form. 

 Many gases have been liquefied ; the carbonic acid gas has been solidi- 

 fied, but hydrogen and nitrogen have resisted all our efi'orts of the 

 kind. Hydrogen in many of its relations acts as though it were a 

 metal; could it be obtained in a liquid or a solid condition the doubt 

 might be settled. This great problem, however, has vet to ])e solved, 

 nor should we look with hopelessness on this solution when we reflect 

 with wonder — and as I do almost with fear and trembling — on the pow- 

 ers of investigating the hidden qualities of these elements — of ques- 

 tioning them, making them disclose their secrets and tell their tales — 

 given by the Almighty to man." 



Faraday's expressed faith in the potentialities of experimental inqiury 

 in 1852 has been justified forty-six years afterwards by the production 

 of liquid hydrogen in the very laboratory in which all his epoch- 

 making researches were executed. The "" doubt" has now been settled; 

 hydrogen does not possess in the liquid state the characteristics of a 

 metal. No one can predict the properties of matter near the zero of 

 temperature. Faraday licj[uefied chlorine in the year 1823. Sixty 

 years afterwards, Wroblewski and Olszewski produced liquid air, and 

 now, after a fifteen years' interval, the last of the old permanent gases, 

 hydrogen, appears as a static liquid. Considering that the step from 

 the liquefaction of air to that of hydrogen is relatively as great in the 

 thermodynamic sense as that from liquid chlorine to licpiid air, the 

 fact that the former result has been achieved in one-fourth the time 

 needed to ascomplish the latter proves the greatly accelerated pace of 

 scientific progress in our time. 



The eflicient cultivation of this field of research depends on combi- 

 nation and assistance of an exceptional kind; but in the first instance 

 money must be available, and the members of the Royal Institution 

 deserve m}^ especial gratitude for their handsome donations to the 

 conduct of this research. Unfortunately its prosecution will demand 

 a further large expenditure. It is my duty to acknowledge that at an 

 early stage of the inquiiy the Hoii. Company of Goldsmiths helped low- 

 temperature investigation by a generous donation to the research 

 fund. 



* See Faraday's Lectures ou the Noniuetallic P^lements, pp. 292-293. 



