April 27, 1900.] 



SCIENCE. 



651 



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 non- 

 metallic elements delivered at the Royal 

 Institution in 1852, and published the fol- 

 lowing year, Faraday said:* "There is 

 reason to believe we should derive much 

 information as to the intimate nature of 

 these non-metallic elements, if we could 

 succeed in obtaining hydrogen and nitrogen 

 in the liquid and solid form. Many gases 

 have been liquefied : the carbonic acid gas 

 has been solidified, but hydrogen and nitro- 

 gen have resisted all our efforts of the kind. 

 Hydrogen in many of its relations acts as 

 though it were a metal ; could it be ob- 

 tained in a liquid or a solid condition, the 

 doubt might be settled. This great prob- 

 lem, 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 potenti- 

 alities 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-mak- 

 ing 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 prop- 

 erties of matter near the zero of tempera- 

 ture. Faraday liquefied chlorine in the 

 year 1823. Sixty years afterwards Wro- 

 blewski 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 



*See Faraday's Lectures on the Non-Metallic Ele- 

 ments, pp. 292-3. 



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 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 pace of 

 scientific progress in our time. 



The efiScient cultivation of this field of 

 research depends on combination and as- 

 sistance of an exceptional kind ; but in the 

 first instance money must be available, and 

 the members of the Royal Institution de- 

 serve my especial gratitude for their hand- 

 some donations to the conduct of this re- 

 search. Unfortunately its prosecution will 

 demand a further large expenditure. It is 

 my duty to acknowledge that at an early 

 stage of the inquiry the Hon. Company of 

 Goldsmiths helped low temperature inves- 

 tigation by a generous donation to the Re- 

 search Fund. 



During the whole course of the low-tem- 

 perature work, carried out at the Royal 

 Institution, the invaluable aid of Mr. Rob- 

 ert Lennox has been at my disposal, and it 

 is not too much to say that, but for his 

 engineering skill, manipulative ability and 

 loyal perseverance, the present successful 

 issue might have been indefinitely delayed. 

 My thanks are also due to Mr. J. W. Heath 

 for valuable assistance in the conduct of 

 the experiments. 



James Dewar. 



S03IE RECENT CONTRIBUTIONS TO TER- 

 RESTRIAL MAGNETISM* 



During the past five years a most re- 

 markable interest in magnetic work has 

 been shown throughout the civilized world. 

 The present time can well be likened to the 

 years when Gauss inaugurated a Magnetic 

 Association, consisting of investigators from 

 all countries, in order to carry out observa- 



*A paper read before the Philosophical Society 

 of Washington, March 17, 1900. 



