79 



Under its own vapoiirpressure and a boilingpointeurve. (Generally we 

 now have : when the vapour pressure at a constant T decreases (or 

 increases) from the pure sohition, the boilingpoint under a constant 

 P will increase (or decrease). 



This, however, is no more the case for solutions between the 

 point of maximumpressure and the point of maximumtemperature. 

 The poiid. of maximumpressure is situated viz. closer to the point 

 6" than the point of ina\inium!empcrature. When we take a solution 

 between these points, it is a solution I'ich in water with i-espect to 

 the salurationcurve under its own vapourpi-essui-e, a solution poor 

 in watei', however, with res})eci to the boilingpointeurve. (lonseipiently 

 as well the pressure along- the saturatioucurve as the lemperat\ne 

 along the l)oilingpointcurve will decrease from this solution. 



We may expi-ess the foregoing also in the following way: the 

 vapourpressure (at constant 7^) and the boilingpoint (under constant 

 P) change from a pure solution generally in opposite directions. 

 When, however, the pure solution is situated between the point of 

 maximumpressure and the |)oint of maximumtem[)erature, then as 

 well the vapourpressure as the boiling[»oiid decrease from this solution. 



Formerly we have already considered the saturatioucurve under 

 its own vapourpressure of two solid substances (viz. the equilibrium 

 F -{- F' -^ L -\- G) ; now we shall discuss some points more in detail. 

 It should be kept in nxind in this case that all deductions apply 

 also now to pomts, \n hicli are not situated in the vicinity of AB. 

 The deductions discussed already formerly apply to points in the 

 vicinity of this line. 



Ijet ns take the solution m of fig. 2 saturated with ^ -[- 7?, there- 

 fore, the equilibrium A -j- B -\- L,,^ -\- G. As the pressure increases 

 from m towards c and towards ƒ, we may say : the solution saturated 

 with two components has a smaller vapourpressure than the pure 

 solution of each of the components separately. 



When we consider the solution /> of fig. 2 saturated with ice -\-A 

 and when we imagine curve np to be extended up to (Z.4, it appears: 

 the solution saturated with ice -\- A has a greater va[)Ourpressure 

 than the solution saturated with ^ -[" ^-* ^^^^d a smaller vai)Ourpressure 

 than the metastable pure solution of A. 



In the previous communication we have already discussed the 

 curves zu, ci', and zw; zii represents the solutions of the equilibrium 

 A -\- B -\- L -\- G, ziv those of the cquililu-ium ice -{- A -\~ L -{- G 

 and zv these of the eipdlibrium ice -(- B -\- L -\- G, w and v arc 

 binary, z is the tei'uary cryohydric point under its own vapourpressure. 



