1905.] on Neiv Low Temperature Phenomena. 183 



The general results are seen best when the values of the thermal 

 evolution and the amount of charcoal involved are reduced to 

 molecular volumes of the condensed gas. 



Heat Evolution. 

 Charcoal absorption per Molecular Volume. 



Calories. Wght. of Charcoal. 



Hydrogen 1600 . . . . 206 grms. 



Nitrogen 3686 



Argon 3636 



Oxygen 3744 



Carbonic Oxide 3416 



Carbonic Oxide and Oxygen . . . . 3960 



Electrolytic Gas 2414 



Mean Cj^M ; limit CgHj and CuHe. 



180 

 162 

 160 

 148 

 144 

 180 



A comparison of the molecular latent heats of the liquefied gases, 

 hydrogen, nitrogen and oxygen, with the charcoal heat of condensa- 

 tion in each case, is shown in the following table : — 



Molecular Molecular Absorption 

 Latent Heats. in Charcoal. 



(Calories) (Calories) 



Hydrogen 238 . . . . 1600 



Nitrogen 1372 . . . . 3684 



Oxygen 1664 .. .. 3744 



But perhaps the most striking result is the great difference in 

 properties exhibited by helium. While resembling other cases in 

 showing increased absorption at the temperature of liquid air, the 

 absolute amount occluded is about one-tenth that of the other gases 

 at the same temperature, and the quantity of heat evolved is in even 

 a smaller ratio. We must, however, note that the position of helium 

 on the scale of temperatures, for these experiments, is quite different 

 from that of the other gases, even hydrogen. For helium is being 

 absorbed at a temperature some fifteen times higher than its boiling 

 point (say 6° abs.), while in the case of hydrogen this is only four- 

 and-a-half times its boiling point (20° abs.). To make a fair 

 comparison, we should take hydrogen at fifteen times its boiling 

 point, which would bring us up to some 27° C, that is, the helium 

 absorption at — 185° 0. should preferably be compared with the 

 hydrogen absorption at 0° C. The inference then is, that if we had 

 the absorption of hehum at 25° to 80° absolute, we should find it 

 show a still more remarkable condensation than hydrogen does at 

 90° abs. (- 18:)° abs.). 



The following experimental results confirm this point of view : — 



Helium and Hydrogen. 

 Charcoal Absorption at the Temperatures of Boiling and Solid Hydrogen. 



Helium. Hydrogen. 



Temperature. Vols, of Carbon. Vols, of Carbon. 



-185° C. (boiling point of liquid air) 2^ 137 



— 210° C. (liquid air under exhaustion) 5 180 



-252° C. (boiling point of liquid hydrogen) 160 258 



-258° C. (solid hydrogen) 195 



