182 



Substituting these values in (40) we find : 



2{>/,-^)RT^ = ajt"- (42) 



wherein a has the same vahie as in (21) (XII). 



From this it follows Avith the aid of the first relation (41) that: 



2(y-iJ)«ï'S = T-^j7riT • .. • • . (43) 

 In the same way as in (XII) we find that we may write for this : 



2^^'ê- r~^V^'^ • . . . . (44) 



(..-/^)(.-^) 



dH 

 wherein — ^ is fixed by (24) (XII). From Ihis it follo^ys that the 



curve going in fig. 4 through the point H is parabolicaily curved 



in this point and touches the side BC in this point. 



dH 

 As in this point y — /i <^ 0, ii^—y<^0, y^ — /^ <C ^^ ^^n^i ]> 0' 



ê is always negative. From this it follows that this parabola has 

 only the point H in common with the triangle and is further 

 situated completely outside the triangle. Consequently only the point 

 H represents a liquid ; its other points have no meaning. 



{To he continued). 



Chemistry. — ''The system Ammonia-water". By Prof. A. Smits 

 and S. PosTMA. (Communicated by Prof. J. D. v. n. Waals). 



(Communicated in tlie meeting of May 30, 1914). 



After the preliminary communication ^) on this subject the inves- 

 tigation of the system NHg-H^O has been continued in different 

 directions, and it has now been completed. 



The continued research was directed in the first place to the 

 accurate determination of the meltingpoint lines, corresponding 

 with the pressure of one atmosphere. These determinations, which 

 were now carried out l)y means of a gauged resistance thermo- 



ij These Proc. XH, p. 186. 



