Temperature of Hydrogen. 



281 



pressures H must be included, see fig. 2.) By these con- 

 siderations the nature of the phenomenon which Prof. Ols- 

 zewski described as sudden ebullition may, perhaps, be 



Fiff. 2. 



thermodynamically explained. He observed the liquefied 

 droplets disappear again rapidly as soon as formed ; this, it 

 seems to us, may be directly the effect of the expansion itself, 

 if the pressure H is reached soon after Q is reached. Thus 

 the values 18 and 16 atm. quoted by Prof. Olszewski may 

 possibly represent some intermediate pressures between the 

 corresponding Q and H ; and if such be the case, still easier 

 will it be to explain why these values decrease rapidly below 

 the critical point. 



The last question we propose to examine is, Can the situa- 

 tion of the points of inversion be evaluated for hydrogen ? 

 Since with regard to this no source of information of any 

 trustworthiness whatever seems to be open to us, we venture, 

 with much diffidence, to advance the supposition that the 

 points of inversion may be thermodynamically correspondent 

 temperatures ; that is, if we define t* to mean T*/T c , and t** 

 likewise to mean T**/T c , that for different bodies the values 



Phil. Mag. S. 5. Vol. 40. No. 244. Sept. 1895. U 



