210 Critical and Boiling Temperatures of Hydrogen. 



The results of this experiment are contained in the following 

 table : — 



Pressure of the 

 Oxygen. 



Temperature of Liquid 



Oxygen determined by 



means of a Hydrogen 



Thermometer. 



Temperature of Liquid 



Oxygen determined by 



means of the Expansion 



Method. 



50 # 8 atm. (crit. press.) 

 32-6 „ 



-118° -8 (crit. temp.) 

 -130°-3 



from -118° to -119° -2 

 (crit. temp.) 

 -130° 



19-0 „ 





-140° -5 



10-2 „ 



-151°-6 



-152° 



i-o „ 



from-181°-4to-182°-7 



from -181°-3to -182°"5 





(boiling temp.) 



(boiling temp.) 



This hardly expected agreement of the results obtained 

 by means of both methods shows that the objections we have 

 stated above are not justified, and that the expansion method 

 is quite suitable for determining the critical and the boiling 

 temperatures of gases. The agreement of these results was 

 doubtless also strengthened by the circumstance that the 

 temperatures of oxygen had not been extrapolated, but were 

 calculated by interpolation. The initial temperature of oxygen 

 was, it is true, only 16° higher than its critical temperature, 

 while the initial temperature of hydrogen was about 26° 

 above its critical point ; but I endeavoured to compensate 

 the untoward influence of that circumstance by using a much 

 higher pressure, surpassing by 50 to 60 atm. the initial 

 pressure used in the experiments with oxygen. 



In conclusion, I must mention that my colleague Prof. L. 

 Natanson has shown that the expansion method which I have 

 used and described here can be justified theoretically on the 

 basis of thermodynamic considerations*. Shortly before I 

 performed these experiments, Prof. Natanson also calculated 

 and published the probable critical and boiling temperatures 

 of hydrogen f on the basis of the law of corresponding tem- 

 peratures, and the numbers given by him are sufficiently in 

 agreement with those experimentally found hy myself. 



* Bullet. Intern, de VAcad. de Crac. April 1895, p. 130. 

 t Ibidem, March 1895, p. 93, 



