The particular point, now, to which it is desired to draw attention is this. Suppose the ternary eutectic curves projected on a plane parallel to the face of the prism containing B and C, _i.e._ suppose the concentrations of the two components B and C, between which interaction can occur, expressed in terms of a constant amount of the third component A,[332] curves will then be obtained which are in every respect analogous to the freezing point curves of binary systems. Thus, suppose the eutectic curves _k__{1}K and _k__{2}K in Fig. 95 projected on the face BC of the prism, then evidently a curve will be obtained consisting of two branches meeting in an eutectic point. On the other hand, the projection of the ternary eutectic curves in Fig. 97 on the face BC of the prism, will give a curve consisting of three portions, as shown by the outline _k__{1}K_{1}K_{2}_k__{2} in Fig. 97. Various examples of this have been studied, and the following table contains some of the data for the system ethylene bromide (A), picric acid (B), and [beta]-naphthol (C), obtained by Bruni.[333] {257} ------------------------------------------------------------------------- | Temperature | Solid phases present. ------------------------------------------------------------------------- Point _k__{1} | 9.41° | Ethylene bromide, picric acid. Curve _k__{1}K_{1} | -- | " " Point K_{1} | 9.32° | Ethylene bromide, picric acid, and | | [beta]-naphthol picrate. Curve K_{1}D'K_{2} | -- | Ethylene bromide, | | [beta]-naphthol picrate. Point D' | 9.75° | " " " " Point K_{2} | 8.89° | " " [beta]-naphthol, | | and picrate. Curve K_{2}_k__{2} | -- | " " [beta]-naphthol. Point _k__{2} | 9.04° | " " " ------------------------------------------------------------------------- From what has been said, it will be apparent that if the ternary eutectic curve of a three-component system (in which one of the components is present in constant amount) is determined, it will be possible to state, from the form of curve obtained, whether or not the two components present in varying amount crystallize out pure or combine with one another to form a compound. It may be left to the reader to work out the curves for the other possible systems; but it will be apparent, that the projections of the ternary eutectic curves in the manner given will yield a series of curves alike in all points to the binary curves given in Figs. 63-65, pp. 208-210.