18(j 



It is at once apparent from the determination of the melting-point 

 diagram that the two chemical compounds, one with 2 mol. of 

 NH3 to 1 mol. of HjjO, and the other with 1 mol. of NH^ to 1 mol. 

 of H2O are already considerably dissociated in liquid state at the 

 temperature of solidification. 



Boiling-point lines. 



After centainty had been obtained in the way described here 

 about the existence of two solid compounds between NH3 and H^O, 

 i( was of importance to examine whether the existence of these 

 coropoimds in the liquid state would also follow from the boiling- 

 point lines observed at different pressures. These determinations, 

 which were carried out with an apparatus as was used by 

 Dr. DE Leeuw ^); yielded the result that there was no indication to 

 be perceived that could point to the existence of compounds in the 

 liquid. Hence it followed from this that at the observed boihng 

 temperature the dissociation was already too strong, and that the 

 investigation has therefore to be continued at still lower pressures. 



As the dynamic method is attended with all kinds of difficulties 

 at low |)ress;ire, it was desirable to apply the statistic and not the 

 dynamic method in the continuation of this investigation, and deter- 

 mine the vapour pressure line of different mixtures of definite 

 concentration, from which the boiling-point lines and the ;>iv-lines 



i) Z.f. phys. Ghem. 77, 284 (1911). 



