^ /=: /: ^ 



I2S 



We firstly detenniiic now tlie posilion of (2). It is apparent tVoiTi 

 equation 11 tiuxl tlio riirvcs (1) and (2) are siliiated at diHereiit sides of 

 (3); as (J) is taken ut the right of (3), (2) nmsl, therefore, bc situ- 

 ated at the left of (3). It is apparent from equation 13 that the 

 curves (2) and (3) are situated at different 

 sides of (1); as (3) has been taken at the 

 left of (1), (2) must consequently be situated 

 at the right of (1). 



Tiierefore, we find : curve (2) is situated 

 at the left of (3) and at the right of (1) ; 

 it is situated, therefore, as is drawn in 

 tig. 2 between the nietastable parts of (i) 

 and (3). 



Now we determine the position of (4). 

 '^' "' It is apparent from equation 11 that fl) 



and (4) are situated at the same side of (3) ; (4) is, therefore, situated 

 at the right of (3). It is apparent from equation (13) that (3) and 

 (4) are situated at different sides of (1) ; consequently (4) is situated 

 at the riglit of (1). 



Consequently we find : curve (4) is situated at the I'ight of (1) 

 and (3); it is situated, therefore, as is also drawn in fig. 2, between 

 the stable part of (1) and the nietastable part of (3). 

 From fig. 2 still follow the relations: 



2:^1+3 . . . . (14) :H;±1 + 4 . . . . (16) 



and 

 (2) 1(4)1(1) (3) . . . (15) (3) 1(2)1(1) (4) . . . (17) 



As the position of the curves with respect to one another, is 

 already fixed in fig. 2, we need no more the relations 14— 17, they 

 may however be useful as a confirmation. From (15) follows that 

 (1) and (3) are situated at the one side and (2) at the other side of 

 (4); in accordance with (17) (1) and (4) are situated at the one 

 side and (3) at the other side of (2\ We see that this is in accord- 

 ance with fig. 2. Consequently we find the following rule : 



when we call, going from tiie one component towards the other, 

 the phases occurring in a qiuxdruplepoint F^, I<\, F^ and F^ then 

 the order of succession of the curves, if we move in the P, 7-diagram 

 around the quadruplepoint, is 1, 3, 2, 4 or reversally. 



We have assumed at the deduction above that curve (3) is 

 situated at the left of (1) ; when we fake (3) at the right of (1) 

 wo find the same order of succession. 



