169 



at infinitv of the .I'-axis and liavino- j|ie parabola W^ as directrix 

 (i.e. : enveloping the parabola Y^J. The parameter (of the perpen- 

 dieidar transverse section) of tiiis cviinder is the reciprocal value 

 of the weight ^/.i of the variable .r. 



The equipotential lines in 2 = are the honiothctic ellipses 

 [/>i 1"'] = const. Such an ellipse is the locus of the points of equal 8. 



When the (rigorous) equation of condition is: .u = const... tlie 

 parabola ^f'\ is parallel to the plane x = 0. The tangent cylinder is 

 then infinitely narrow; its parameter is 0, the weight of .i' is infinite. 



Chemistry. — ''Equilibria in ternary systems. XVI. By Prof. F. 



A. H. SCHRETNEMAKERS. 



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



Now we shall consider the case that the vapour contains two 

 components. 



We assume that of the components A, B, and C only the com- 

 ponent B is exceedingly little volatile, so that practically we may 

 say that the vapour consists only of A and C. This is for instance 

 the case when i^ is a salt, w^hich is not volatile, and when A and 

 C are solvents, as w^ater, alcohol, etc. 



Theoretically the vapour consists oidy of A-\- B-\- C; herein the 

 quantity of B is however exceedingly small in comparison with the 

 quantity of A and C. so that the vapour consists practically totally 

 of A and C. 



When, however, we consider complexes in the immediate vicinity 

 of the point B, the relations become otherwise. The solid or liquid 

 substance has viz. always a vapour-pressure, although this is some- 

 times immeasurably small ; therefore, a vapour exists however, 

 which consists only of B. without A and C. When we now^ take a 

 liquid or a complex in the immediate vicinity of point B, the 

 quantity of B in the vapour is then still also large and is not to be 

 neglected in comparison with that of A and C. 



Consequently, when we consider equilibria, not situated in the 

 vicinity of point B, then we may assume that the vapour consists 

 only of A and C; when these equilibria are situated, however, in 

 the immediate vicinity of point B, we must also take into consider- 

 ation the volatility of B and we must consider the vapour a» ternary. 



When we consider only the occurrence of liquid and gas, then, 

 as we have formerly seen, three regions may occur, viz. the gas- 

 region, the liquid-region and the region L — G. This last region is 



