413 



Tlie second iMterseclioii of (hese lines occnn-ing in this lignrc is of 

 course quite incidental, i.e. the point of intersection has no special 

 physical signification. 



Finally I have given in fig. 4 the P-x section for the temperature 

 of the critical endpoint. In this section the initial and the final 

 condensations of the hexane layer are found ; the liquid branch is 

 again in connection witii the vapour branch in the ci-itical endpoint ; 

 the retrograde porti(-n of the vapour branch is only narrow. The 

 above-mentioned ninth mixture has served to determine the point of 

 the vapour bi-anch which lies at higher water concentration than 

 the critical endpoint. 



5. When #e now review the results yielded by this investigation, 

 it appears that this system really belongs to the type whicli we 

 denoted by 1 in §1; in the J'-.i' projection the critical line, namely, 

 descends, proceeding from the hexane side towards greater water 

 concentration; a minimum temperature is, however, not reached, as 

 the endpoint of the three-phase line appears before that time. Hence 

 the minimum that was to be expected lies in the covered region. 

 It is, however, remarkable that the T-.r-projection does not betray 

 the tendency towards this minimum; if there is question of a curva- 

 ture, it would sooner have the opposite sign. And an analogous 

 particularity also presents itself in the P-T projection; the curvature 

 of this projection would theoretically have to be expected so, that 

 the tendency to the reaching of a vertical tangent is expressed ; the 

 curvature lies here, however, certainly to the other side. So in con- 

 nection with the theoretical considerations we should have to conclude 

 here to the existence of a point of inflection in the plaitpoint line 

 in the covered region. 



6. When comparing the pressures of the threephase equilibrium 

 with the vapour tensions of the two components, we come to the 

 remarkable conclusion tliat the thrce-pliase pressure is higher than 

 the sum of the vapour tensions of the components at the same temper- 

 ature. This conclusion appears from table 2, in which the difference 

 between the three-phase pressure and the sum of the vapour pressures 

 for some temperatures ai'e given. 



The difference of presoui'e appears to increase with the tempera- 

 ture, so that it has reached its greatest value of a little more than 

 three atmospheres at the critical endpoint. 



These facts seem astonishing at first sight, because one is natur- 

 ally inclined to consider the vapours of the two components and 



