[mctaggart-edwards] 



METHANE- NITROGEN 



63 



bottle containing the mixture was then connected to (b) and the 

 vacuum flask with the bath of hquid oxygen placed in position. The 

 temperature of the bath was then lowered if necessary by exhausting 

 through (g). The liquefaction of any mixture took place quite 

 readily when the temperature of the bath was kept about 5°C. below 

 the boiling point of the mixture. When 7 or 8 litres had liquefied 

 the flow was stopped and the vapour pressure allowed to rise to 1 

 atmosphere. This was done by raising the temperature of the bath 

 or, in some cases, by lowering the bath. While the vapour pressure 

 was kept at 1 atmosphere samples of both phases were taken, the 

 first portion drawn off being rejected in each case. The liquid was kept 

 thoroughly stirred to avoid any superheating and to ensure as com- 

 plete an equilibrium as possible between the two phases. 



Results 

 The experimental results are given in Table I. 



Table I 



These numbers are shown graphically in Fig. 4 which consti- 

 tutes a temperature-composition diagram. 



In Fig. 5 the composition of the liquid phase is plotted against 

 that of the vapour phase, a few additional observations being added 

 for which temperatures were not determined. 



From this curve the relation : 



where 



log r =a-fb log r 



% Methane 



r =the ratio, in liquid 



% Nitrogen 



