( 102 ) 



pressure that this has not been determined, the second T^ at a 

 moderate pressure is situated at the side of the aniline. The minimum 

 Tj is situated at the same side and is removed further from the 

 melting point than in Fig. 1. 



1\ minimum 7^ melting point 

 p 16 cM. 22.5 cM. 



t 197° 199°2 



The determination of these lines and also that of the equilibria- 

 lines foi- compound -f- vapour or liquid -|- vapour which also occur 

 in both figures can only take place on either side of point F, for 

 in measuring the pressures, we can only have in the apparatus 

 a larger, or smaller, excess of either component. Moreover, it is 

 possible to fdl the apparatus with the compound in a dry and pure 

 condition. In the case of the compounds employed, this was attained 

 by preparing very pure crystals by repeated sublimation in vacuo. 



In the second example, the sublimation line LG oï aniline hydro- 

 chloride was thus determined. On this line then follows the piece 

 GF of the three-phase line, because beyond G, no vapour can exist 

 which has the same composition as the compound, except in the 

 presence of some excess of HCl, so that a little liquid is formed 

 with a slight excess of aniline. If, however, the apparatus is properly 

 filled with the compound so that there remains but little space for 

 the vapour then «the three-phase line G may be traced to very near 

 the melting point F, where one passes on to the line FA, for the 

 equilibrium of the fused compound with its vapour. 



We have here, therefore, the first experimental confirmation of 

 the normal succession of the ^?, Mines when those are determined 

 with a pure compound which dissociates more or less. 



Theoretically, the minimum T^ in the three-phaseline must be 

 situated at the left of the terminal point G of the sublimationline. 

 The difference here, although small, is yet perfectly distinct: 



T, G 



p 16 cM. 16.5 cM. 



/ 197° 198° 



In the case of chloralalcoholate the points 7\ and G both coincide 

 so nearly with F that this point is practically undistinguishable from 

 ihe triple point of a non-dissociating compound, both LF and FA, 

 or their mctastable pi'olongation FA' appear to intersect in F. Moreover, 

 the investigation of the melting point line proved tliat chloralalco- 

 holate in a melted comlilion is but little dissociated. 



