Figure ��For weak attraction between unlike components, a longitudinal plait is always present, and gives rise to a three-phase region and a transverse plait as the temperature decreases. Copied from Korteweg (b), Plate XIII.Korteweg labels the case of k < 1/9 with the letter A. For this case, near the top of the K&S diagram, Fig. �� T1' is much larger than T1, and thus the longitudinal plait already appears at temperatures too high for the transverse plait to exist. As the system cools, two accessory plaits form, and finally a full transverse plait develops. The fate of the longitudinal plait, marked A1, is quite interesting. As the temperature falls, it grows to larger volumes. At a certain temperature, the plait point splits into three plait points, two of the first, and one of the second kind. Two accessory plaits form, and a three-phase region vaporliquid-liquid appears, see A2 The point at which the plait point of the longitudinal plait splits in three (presently called a symmetric tricritical point) is the last stable plait point of the longitudinal plait as the temperature falls. As the temperature decreases, the two stable plait points trace two new critical lines that end at the critical points of the two components. The tricritical point is therefore also an�︼�★�わ★潷 �澊ワ澐ワ潷, ワワ ★��★
