264 LIQUEFACTION OF HYDROGEN AND HELIUM. 



helium, which had been extracted from Bath gas, sealed up in a bulb 

 with a narrow tube attached, the latter was placed in liquid hydrogen, 

 when a distinct liquid was seen to condense. The same experiment 

 repeated, only using liquid air evaporating in a vacuum, gave no trace 

 of condensation. From this result it would appear that there can not 

 be any great difference between the boiling points of helium and 

 hydrogen. 



All known gases have now been condensed into liquids which can be 

 manipulated at their boiling points under atmospheric pressure in 

 suitably arranged vacuum vessels. With hydrogen as a cooling agent 

 we shall get within 20 or 30 of the zero of absolute temperature, and 

 its use will open up an entirely new field of scientific inquiry. Even 

 as great a man as James Clerk Maxwell had doubts as to the possibility 

 of ever liquefying hydrogen. (See Scientific Papers 2, 412.) In conclud- 

 ing his lectures on the non metallic elements, delivered at the Eoyal 

 Institution in 1852 and published the following year, Faraday said: 1 



" There is reason to believe we should derive much information as to 

 the intimate nature of these nonmetallic elements if we could succeed 

 in obtaining hydrogen and nitrogen in the liquid or solid form. Many 

 gases have been liquefied ; the carbonic acid gas has been solidified, but 

 hydrogen and nitrogen have resisted all our efforts of the kind. Hydro- 

 gen in many of its relations acts as though it were a metal; could it be 

 obtained in a liquid or solid condition the doubt might be settled. This 

 great problem, however, has yet to be 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 powers of investigating the 

 hidden qualities of these elements — of questioning 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 inquiry 

 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; hydro- 

 gen does not possess in the liquid state the characteristics of a metal. 

 No one can predict the properties of matter near the zero of tempera- 

 ture. Faraday liquefied chlorine in the year 1823. Sixty years after- 

 wards Wroblewski and Olszewski produced liquid air, and now, after 

 a fifteen years' interval, the remaining gases, hydrogen and helium, 

 appear as static liquids. Considering 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 liquid air, the fact that the former 

 result has been achieved in one-fourth the time needed to accomplish 

 the latter proves the greatly accelerated race of scientific progress in 

 our time. 



The efficient cultivation of this field of research depends upon com- 

 bination and assistance of an exceptional kind, but in the first instance 

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



1 See Faraday's "Lectures on the lionruetallic elements/' pp. 292-293. 



